Poor Li plating reversibility and high thermal runaway risks are key challenges for fast charging lithiumion batteries with graphite anodes.Herein,a dielectric and fire-resistant separator based on hybrid nanofibers o...Poor Li plating reversibility and high thermal runaway risks are key challenges for fast charging lithiumion batteries with graphite anodes.Herein,a dielectric and fire-resistant separator based on hybrid nanofibers of barium sulfate(BS)and bacterial cellulose(BC)is developed to synchronously enhance the battery's fast charging and thermal-safety performances.The regulation mechanism of the dielectric BS/BC separator in enhancing the Li^(+)ion transport and Li plating reversibility is revealed.(1)The Max-Wagner polarization electric field of the dielectric BS/BC separator can accelerate the desolvation of solvated Li^(+)ions,enhancing their transport kinetics.(2)Moreover,due to the charge balancing effect,the dielectric BS/BC separator homogenizes the electric field/Li^(+)ion flux at the graphite anode-separator interface,facilitating uniform Li plating and suppressing Li dendrite growth.Consequently,the fast-charge graphite anode with the BS/BC separator shows higher Coulombic efficiency(99.0%vs.96.9%)and longer cycling lifespan(100 cycles vs.59 cycles)than that with the polypropylene(PP)separator in the constantlithiation cycling test at 2 mA cm^(-2).The high-loading LiFePO4(15.5 mg cm^(-2))//graphite(7.5 mg cm^(-2))full cell with the BS/BC separator exhibits excellent fast charging performance,retaining 70%of its capacity after 500 cycles at a high rate of 2C,which is significantly better than that of the cell with the PP separator(retaining only 27%of its capacity after 500 cycles).More importantly,the thermally stable BS/BC separator effectively elevates the critical temperature and reduces the heat release rate during thermal runaway,thereby significantly enhancing the battery's safety.展开更多
Increasing the energy density of conventional lithium-ion batteries(LIBs)is important for satisfying the demands of electric vehicles and advanced electronics.Silicon is considered as one of the most-promising anodes ...Increasing the energy density of conventional lithium-ion batteries(LIBs)is important for satisfying the demands of electric vehicles and advanced electronics.Silicon is considered as one of the most-promising anodes to replace the traditional graphite anode for the realization of high-energy LIBs due to its extremely high theoretical capacity,although its severe volume changes during lithiation/delithiation have led to a big challenge for practical application.In contrast,the co-utilization of Si and graphite has been well recognized as one of the preferred strategies for commercialization in the near future.In this review,we focus on different carbonaceous additives,such as carbon nanotubes,reduced graphene oxide,and pyrolyzed carbon derived from precursors such as pitch,sugars,heteroatom polymers,and so forth,which play an important role in constructing micrometersized hierarchical structures of silicon/graphite/carbon(Si/G/C)composites and tailoring the morphology and surface with good structural stability,good adhesion,high electrical conductivity,high tap density,and good interface chemistry to achieve high capacity and long cycling stability simultaneously.We first discuss the importance and challenge of the co-utilization of Si and graphite.Then,we carefully review and compare the improved effects of various types of carbonaceous materials and their associated structures on the electrochemical performance of Si/G/C composites.We also review the diverse synthesis techniques and treatment methods,which are also significant factors for optimizing Si/G/C composites.Finally,we provide a pertinent evaluation of these forms of carbon according to their suitability for commercialization.We also make far-ranging suggestions with regard to the selection of proper carbonaceous materials and the design of Si/G/C composites for further development.展开更多
Silicon/graphite(Si/Gr)nanocomposites with controlled void spaces and encapsulated by a carbon shell(Si/Gr@void@C)are synthesized by utilizing high-energy ball milling to reduce micron-sized particles to nanoscale,fol...Silicon/graphite(Si/Gr)nanocomposites with controlled void spaces and encapsulated by a carbon shell(Si/Gr@void@C)are synthesized by utilizing high-energy ball milling to reduce micron-sized particles to nanoscale,followed by carbonization of polydopamine(PODA)to form a carbon shell,and finally partial etching of the nanostructured Si core by NaOH solution at elevated temperatures.In particular,the effects of ball milling time and NaOH etching temperature on the electrochemical properties of Si/Gr@void@C are investigated.Increasing the ball milling time results in the improved specific capacity of Si-based anodes.Carbon coating further enhances the specific capacity and capacity retention over charge/discharge cycles.The best cycle stability is achieved after partial etching of the Si core inside Si/Gr@void@C particles at either 70 or 80C,leading to little or no capacity decay over 130 cycles.However,it is found that both carbon coating and NaOH etching processes cause some surface oxidation of the nanostructured Si particles derived from high-energy ball milling.The surface oxidation of the nanostructured Si results in decreases in specific capacity and should be minimized in future studies.The mechanistic understanding developed in this study paves the way to further improve the electrochemical performance of Si/Gr@void@C nanocomposites in future.展开更多
Silicon is believed to be a critical anode material for approaching the roadmap of lithium-ion batteries due to its high specific capacity. But this aim has been hindered by the quick capacity fading of its electrodes...Silicon is believed to be a critical anode material for approaching the roadmap of lithium-ion batteries due to its high specific capacity. But this aim has been hindered by the quick capacity fading of its electrodes during repeated charge–discharge cycles. In this work, a “soft-hard”double-layer coating has been proposed and carried out on ball-milled silicon particles. It is composed of inside conductive pathway and outside elastic coating, which is achieved by decomposing a conductive graphite layer on the silicon surface and further coating it with a polymer layer.The incorporation of the second elastic coating on the inside carbon coating enables silicon particles strongly interacted with binders, thereby making the electrodes displaying an obviously improved cycling stability. As-obtained double-coated silicon anodes deliver a reversible capacity of 2280 m Ah g^(-1)at the voltage of 0.05–2 V, and maintains over 1763 mAh g^(-1)after 50 cycles. The double-layer coating does not crack after the repeated cycling, critical for the robust performance of the electrodes. In addition, as-obtained silicon particles are mixed with commercial graphite to make actual anodes for lithium-ion batteries. A capacity of 714 mAh g^(-1)has been achieved based on the total mass of the electrodes containing 10 wt.% double-coated silicon particles. Compared with traditional carbon coating or polymeric coating, the double-coating electrodes display a much better performance. Therefore, the double-coating strategy can give inspiration for better design and synthesis of silicon anodes, as well as other battery materials.展开更多
Micro-silicon(Si)anode that features high theoretical capacity and fine tap density is ideal for energy-dense lithiumion batteries.However,the substantial localized mechanical strain caused by the large volume expansi...Micro-silicon(Si)anode that features high theoretical capacity and fine tap density is ideal for energy-dense lithiumion batteries.However,the substantial localized mechanical strain caused by the large volume expansion often results in electrode disintegration and capacity loss.Herein,a microporous Si anode with the SiO_(x)/C layer functionalized all-surface and high tap density(~0.65 g cm^(-3))is developed by the hydrolysis-driven strategy that avoids the common use of corrosive etchants and toxic siloxane reagents.The functionalized inner pore with superior structural stability can effectively alleviate the volume change and enhance the electrolyte contact.Simultaneously,the outer particle surface forms a continuous network that prevents electrolyte parasitic decomposition,disperses the interface stress of Si matrix and facilitates electron/ion transport.As a result,the micron-sized Si anode shows only~9.94 GPa average stress at full lithiation state and delivers an impressive capacity of 901.1 mAh g^(-1)after 500 cycles at 1 A g^(-1).It also performs excellent rate performance of 1123.0 mAh g^(-1)at 5 A g^(-1)and 850.4 at 8 A g^(-1),far exceeding most of reported literatures.Furthermore,when paired with a commercial LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2),the pouch cell demonstrates high capacity and desirable cyclic performance.展开更多
In this work,the Si@reduced graphene oxide/ZrO_(2)(Si@rGO/ZrO_(2))with the shelled structures is prepared for the high-capacity and stable lithium-ion batteries.The shelled structure not only significantly improves th...In this work,the Si@reduced graphene oxide/ZrO_(2)(Si@rGO/ZrO_(2))with the shelled structures is prepared for the high-capacity and stable lithium-ion batteries.The shelled structure not only significantly improves the electrical conductivity of the whole electrode,but also protects the inner Si nanoparticles(Si NPs)from rupturing and being damaged by undesired side reactions with the electrolyte.As a result,the Si@rGO/ZrO_(2) anode delivers high initial discharge capacity of 3046 mAh·g^(−1) at 1.0 A·g^(−1).After 100 cycles,it can be maintained at 613 mAh·g^(−1),which is much higher than that of either the pure Si NPs(31 mAh·g^(−1))or the Si@rGO(261 mAh·g^(−1)).Even at 2 A·g^(−1),it still provides superior specific capacity of 834 mAh·g^(−1),while the pure Si anode merely possesses the capacity of 41 mAh·g^(−1).Moreover,the density functional theory calculations point out that ZrO_(2) layer can effectively enhance the adsorption energy of Li+and optimize the migration paths of Li+,ensuring the electrochemical performance of Si@rGO/ZrO_(2) composite anode.Furthermore,the Li+storage mechanism and low volume expansion of Si@rGO/ZrO_(2) anode is investigated by ex-situ X-ray photoelectron spectroscopy and morphological evolution upon cycling,respectively.展开更多
Severe volume changes and poor electrochemical performance are key barriers to the practical use of silicon anodes.In this study,a self-healing,multifunctional supramolecular binder system was introduced,which combine...Severe volume changes and poor electrochemical performance are key barriers to the practical use of silicon anodes.In this study,a self-healing,multifunctional supramolecular binder system was introduced,which combines polymers,ionic liquids,and halometals to achieve dynamic cross linking during volume changes.The addition of specific halometals can adjust the Li+solvation structure and energy,promoting the formation of a stable solid electrolyte interface(SEI)rich in LiF and facilitating Li+desolvation.After 200 cycles,the Si@BF binder(with both ionic liquid and halometal)showed no cracks,indicating excellent structural stability.Additionally,Si||LiFePO_(4)(LFP)full-cell tests at 5 C rate reveal drastic differences:The unmodified binder(the pristine Si)exhibits nearly 0%capacity retention after 400 cycles,the ionic liquid-modified system(Si@B)maintains 11.58%,while Si@BF achieves a remarkable 90.92%retention.Notably,Si@BF retains 78.72%capacity even after 800 cycles.This study offers new insights into dynamic cross-linking systems and solvation-structure regulation,providing references for developing advanced lithium-ion batteries with better performance.展开更多
Silicon(Si)is considered one of the most promising anode materials for next-generation lithium-ion batteries due to its ultrahigh theoretical capacity.However,its application is significantly limited by severe volume ...Silicon(Si)is considered one of the most promising anode materials for next-generation lithium-ion batteries due to its ultrahigh theoretical capacity.However,its application is significantly limited by severe volume expansion,leading to structural degradation and poor cycling stability.Polymer binders play a critical role in addressing these issues by providing mechanical stabilization.Inspired by the mechanically adaptive architecture of spider webs,where stiff radial threads and extensible spiral threads act in synergy,a dual-thread architecture polymer binder(PALT)with energy dissipation ability enabled by integrating rigid and flexible domains is designed.The rigid poly(acrylic acid lithium)(PAALi)segments offer structural reinforcement,while the soft segments(poly(lipoic acid-tannic acid),LT)introduce dynamic covalent bonds and multiple hydrogen bonds that function as reversible sacrificial bonds,enhancing energy dissipation during cycling.Comprehensive experimental and computational analyses demonstrate effectively reduced stress concentration,improved structural integrity,and stable electrochemical performance over prolonged cycling.The silicon anode incorporating the PALT binder exhibits a satisfying capacity loss per cycle of 0.042% during 350 charge/discharge cycles at 3580 m A g^(-1).This work highlights a bioinspired binder design strategy that combines intrinsic rigidity with dynamic stress adaptability to advance the mechanical and electrochemical stability of silicon anodes.展开更多
Polyacrylic acid(PAA)-based binders have been demonstrated to significantly enhance the cycling stability of pure silicon(Si)anodes compared to other binder types.However,there is a notable lack of systematic and in-d...Polyacrylic acid(PAA)-based binders have been demonstrated to significantly enhance the cycling stability of pure silicon(Si)anodes compared to other binder types.However,there is a notable lack of systematic and in-depth investigation into the relationship between the molecular weight(MW)of PAA and its performance in pure Si anodes,leading to an absence of reliable theoretical guidance for designing and optimizing of PAA-based binders for these anodes.Herein,we select a series of PAA with varying MWs as binders for Si nanoparticle(SiNP)anodes to systematically identify the optimal MW of PAA for enhancing the electrochemical performance of SiNP anodes.The actual MWs of the various PAA were confirmed by gel permeation chromatography to accurately establish the relationship between MW and binder performance.Within an ultrawide weight average molecular weight(M_(w))range of 35.9-4850 kDa,we identify that the PAA binder with a M_(w)of 1250 kDa(PAA125)exhibits the strongest mechanical strength and the highest adhesion strength,attributed to its favorable molecular chain orientation and robust interchain interactions.These characteristics enable the SiNP anodes utilizing PAA125 to maintain the best interfacial chemistry and bulk mechanical structure stability,leading to optimal electrochemical performance.Notably,the enhancement in cycling stability of SiNP anode by PAA125 under practical application conditions is further validated by the 1.1 Ah LLNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)/SiNP@PAA125 pouch cell.展开更多
This study presents a novel approach to enhance silicon anode performance through barium titanate(BTO)incorporation,with the establishment of a force-electric coupling model.By introducing piezoelectric BTO into silic...This study presents a novel approach to enhance silicon anode performance through barium titanate(BTO)incorporation,with the establishment of a force-electric coupling model.By introducing piezoelectric BTO into silicon matrices,we successfully improved both the mechanical stability and electrochemical kinetics of the anode.The developed force-electric coupling model explains how BTO mitigates stress accumulation during lithiation while optimizing the kinetics of Li^(+)and electron transfer.Experimental verification and multiphysical simulation indicate that Si@BTO effectively eliminates structural degradation during the cycling process and significantly reduces the charge transfer resistance.The force-electric coupling mechanism further facilitates stable solid electrolyte interphase(SEI)formation.When paired with LiFePO_(4)cathodes,Si@BTO maintains 76% capacity retention after 500 cycles at a 10 C rate.This work establishes a basic force-electric coupling model framework and offers insights into the development of advanced silicon anode batteries with exceptional performance.展开更多
The recently reported silicon/graphite(Si/Gr)composite electrode with a layered structure is a promising approach to achieve high capacity and stable cycling of Si-based electrodes in lithium-ion batteries.However,the...The recently reported silicon/graphite(Si/Gr)composite electrode with a layered structure is a promising approach to achieve high capacity and stable cycling of Si-based electrodes in lithium-ion batteries.However,there is still a need to clarify why particular layered structures are effective and why others are ineffective or even detrimental.In this work,an unreported mechanism dominated by the porosity evolution of electrodes is proposed for the degradation behavior of layered Si/Gr electrodes.First,the effect of layering sequence on the overall electrode performance is investigated experimentally,and the results suggest that the cycling performance of the silicon-on-graphite(SG)electrode is much superior to that of the graphite-on-silicon electrode.To explain this phenomenon,a coupled mechanical-electrochemical porous electrode model is developed,in which the porosity is affected by the silicon expansion and the local constraints.The modeling results suggest that the weaker constraint of the silicon layer in the SG electrode leads to a more insignificant decrease in porosity,and consequently,the more stable cycling performance.The findings of this work provide new insights into the structural design of Si-based electrodes.展开更多
The intrinsic volume changes(about 300%)of Si anode during the lithiation/delithiation leads to the serious degradation of battery performance despite of theoretical capacity of 3579 mAh g^(-1) of Si.Herein,a three-di...The intrinsic volume changes(about 300%)of Si anode during the lithiation/delithiation leads to the serious degradation of battery performance despite of theoretical capacity of 3579 mAh g^(-1) of Si.Herein,a three-dimensional(3D)conductive polymer binder with adjustable crosslinking density has been designed by employing citric acid(CA)as a crosslinker between the carboxymethyl cellulose(CMC)and the poly(3,4-ethylenedioxythiophene)poly-(styrene-4-sulfonate)(PEDOT:PSS)to stabilize Si anode.By adjusting the crosslinking density,the binder can achieve a balance between rigidity and flexibility to adapt the volume expansion upon lithiation and reversible volume recovery after delithiation of Si.Therefore,Si/CMC-CA-PEDOT:PSS(Si/CCP)electrode demonstrates an excellent performance with high capacities of 2792.3 mAh g^(-1) at 0.5 A g^(-1) and a high area capacity above 2.6 mAh cm^(-2) under Si loading of 1.38 mg cm^(-2).The full cell Si/CCP paired with Li(Ni_(0.8)Co_(0.1)Mn_(0.1))O_(2) cathode discharges a capacity of 199.0 mAh g^(-1) with 84.3%ICE at 0.1 C and the capacity retention of 95.6%after 100 cycles.This work validates the effectiveness of 3D polymer binder and provides new insights to boost the performance of Si anode.展开更多
Silicon(Si)anodes,with a theoretical specific capacity of 4200 mAh g^(-1),hold significant promise for the development of high-energy-density lithium-ion batteries(LIBs).However,practical applications are hindered by ...Silicon(Si)anodes,with a theoretical specific capacity of 4200 mAh g^(-1),hold significant promise for the development of high-energy-density lithium-ion batteries(LIBs).However,practical applications are hindered by sluggish charge transfer kinetics,substantial volume expansion,and an unstable solid elec-trolyte interphase during cycling.To address these challenges,we propose a centimeter-scale Si anode design featuring a three-dimensional continuous network structure of Si nanowires(SiNWs)decorated with high-density Ag nanoparticles(Ag-SiNWs-Net)on both the surface and internally.This architecture effectively mitigates mechanical stress from Si volume changes through the high-aspect-ratio wire network.Additionally,the distribution of Ag nanoparticles on the Si induces electronic structure redistribution,generating built-in electric fields that accelerate charge transfer within the Si,significantly enhancing rate performance and cycling stability.The Ag-SiNWs-Net anode achieves a high reversible capacity of 3780.9 mAh g^(-1)at 0.1 A g^(-1),with an initial coulombic efficiency of 85.1%.Moreover,the energy density of full cells assembled with Ag-SiNWs-Net anodes and LiFePO4 cathodes can be pushed further up to 395.8 Wh kg^(-1).This study offers valuable insights and methodologies for the development of high-capacity and practical Si anodes-.展开更多
While silicon/carbon(Si/C)is considered one of the most promising anode materials for the next generation of high-energy lithium-ion batteries(LIBs),the industrialization of Si/C anodes is hampered by high-cost and lo...While silicon/carbon(Si/C)is considered one of the most promising anode materials for the next generation of high-energy lithium-ion batteries(LIBs),the industrialization of Si/C anodes is hampered by high-cost and low product yield.Herein,a high-yield strategy is developed in which photovoltaic waste silicon is converted to cost-effective graphitic Si/C composites(G-Si@C)for LIBs.The introduction of a binder improves the dispersion and compatibility of silicon and graphite,enhances particle sphericity,and significantly reduces the loss rate of the spray prilling process(from about 25%to 5%).As an LIB anode,the fabricated G-Si@C composites exhibit a capacity of 605 mAh g^(-1) after 1200 cycles.The cost of manufacturing Si/C anode materials has been reduced to approximately$7.47 kg^(-1),which is close to that of commercial graphite anode materials($5.0 kg^(-1)),and significantly lower than commercial Si/C materials(ca.$20.74 kg^(-1)).Moreover,the G-Si@C material provides approximately 81.0 Ah/$of capacity,which exceeds the current best commercial graphite anodes(70.0 Ah/$)and Si/C anodes(48.2 Ah/$).The successful implementation of this pathway will significantly promote the industrialization of high-energydensity Si/C anode materials.展开更多
There is an urgent need to develop high-areal-capacity silicon(Si)anodes with good cycling stability and rate capability for high-energy-density lithium-ion batteries(LIBs).However,this remains a huge challenge due to...There is an urgent need to develop high-areal-capacity silicon(Si)anodes with good cycling stability and rate capability for high-energy-density lithium-ion batteries(LIBs).However,this remains a huge challenge due to large volume expansion-induced mechanical degradation and electrical connectivity loss in thick electrodes.Here,a three-in-one strategy is proposed to achieve high-areal-capacity silicon anodes by constructing a multi-level interconnected 3D porous and robust conductive network that carbon nanofibers and vertical carbon nanosheets tightly encapsulate on the surface of Si nanoparticles(Si NPs)anchored in porous carbon felts.This network accommodates large volume expansion of Si NPs to significantly improve electrode mechanical stability and creates excellent electrical connectivity to boost charge transport in thick electrodes,revealed through Multiphysics field simulations and in situ electrochemical techniques.Therefore,the designed Si anodes achieve superior long-term stability with a capacity of 8.13 mAh cm^(-2)after 500 cycles and an ultrahigh areal capacity of 45.8 mAh cm^(-2).In particular,Ah-level pouch cells demonstrate an impressive capacity retention of 79.34%after 500 cycles at 1 C.Our study offers novel insights and directions for understanding and optimizing high-areal-capacity silicon-carbon composite anodes.展开更多
Silicon-based materials are considered as the next generation anode to replace graphite due to their low cost and ultra-high theoretical capacity.However,significant volume expansion and contraction occur during charg...Silicon-based materials are considered as the next generation anode to replace graphite due to their low cost and ultra-high theoretical capacity.However,significant volume expansion and contraction occur during charging and discharging processes,leading to the instability of electrode structure and susceptibility to peeling and damage,limiting its application.Constructing controllable molecular artificial solid electrolyte interphase(CMASEI)is an effective approach to address the commercialization of silicon-based anode materials[1].Improving the performance of silicon-based anodes through CMASEI is a multifaceted outcome.展开更多
Fast-charging lithium-ion batteries are highly required,especially in reducing the mileage anxiety of the widespread electric vehicles.One of the biggest bottlenecks lies in the sluggish kinetics of the Li^(+)intercal...Fast-charging lithium-ion batteries are highly required,especially in reducing the mileage anxiety of the widespread electric vehicles.One of the biggest bottlenecks lies in the sluggish kinetics of the Li^(+)intercalation into the graphite anode;slow intercalation will lead to lithium metal plating,severe side reactions,and safety concerns.The premise to solve these problems is to fully understand the reaction pathways and rate-determining steps of graphite during fast Li^(+)intercalation.Herein,we compare the Li^(+)diffusion through the graphite particle,interface,and electrode,uncover the structure of the lithiated graphite at high current densities,and correlate them with the reaction kinetics and electrochemical performances.It is found that the rate-determining steps are highly dependent on the particle size,interphase property,and electrode configuration.Insufficient Li^(+)diffusion leads to high polarization,incomplete intercalation,and the coexistence of several staging structures.Interfacial Li^(+)diffusion and electrode transportation are the main rate-determining steps if the particle size is less than 10μm.The former is highly dependent on the electrolyte chemistry and can be enhanced by constructing a fluorinated interphase.Our findings enrich the understanding of the graphite structural evolution during rapid Li^(+)intercalation,decipher the bottleneck for the sluggish reaction kinetics,and provide strategic guidelines to boost the fast-charging performance of graphite anode.展开更多
We report the synthesis of a high‐performance graphitic carbon‐coated silicon(Si@GC)composite material for lithium‐ion batteries via a scalable production route.Porous Si is produced from the magnesiothermic reduct...We report the synthesis of a high‐performance graphitic carbon‐coated silicon(Si@GC)composite material for lithium‐ion batteries via a scalable production route.Porous Si is produced from the magnesiothermic reduction of commercial silica(SiO2)precursor followed by low‐temperature graphitic carbon coating using glucose as the precursor.The obtained Si@GC composite achieves an excellent reversible specific capacity of 1195 mAh g−1 and outstanding cycle stability.The thick Si@GC anode(3.4 mg cm^−2)in full cells with commercial lithium iron phosphate cathode delivers a remarkable performance of 800 mAh g^−1 specific capacity and 2.7 mAh cm^−2 areal capacity as well as 93.6%capacity retention after 200 cycles.展开更多
With the increased demand from the storage of renewable energy sources,some safe and inexpensive energy storage technologies instead of Li-ion batteries become urgently needed.Therefore,K-ion batteries(KIBs)have attra...With the increased demand from the storage of renewable energy sources,some safe and inexpensive energy storage technologies instead of Li-ion batteries become urgently needed.Therefore,K-ion batteries(KIBs)have attracted much attention and evolved significant development because of the low price,safety,and similar property compared with Li-ion batteries.Due to the high reversibility,stability,and low potential plateau,graphite becomes a current research focus and is regarded as one of the most promising KIB’s anode materials.In this review,we mainly discuss the electrochemical reaction mechanism of graphite during potassiation-depotassiation process and analyze the effects of electrode/electrolyte interface on graphite for Kion storage.Besides,we summarize several kinds of methods to improve the performance of graphite for KIBs,including the design of graphite structure,selection of appropriate binder,solvent chemistry,and salt chemistry.Meanwhile,a concept of“relative energy density”is raised,which can be more accurate to evaluate the genuine electrochemical performance of graphite anode involving the specific capacity and potential.In addition,we also summarize the considerable challenges to current graphite anode in KIBs and we believe our work will offer alterative solutions to further explore high-performance graphite anode of K-ion storage.展开更多
Natural minerals-based energy materials have attracted enormous attention because of the advantages of good materials consistency,high production,environmental friendliness,and low cost.The uniform distribution of gra...Natural minerals-based energy materials have attracted enormous attention because of the advantages of good materials consistency,high production,environmental friendliness,and low cost.The uniform distribution of grains can effectively inhibit the aggregation of active materials,improving lithium storage performance.In this work,natural graphite is modified by polyvinylpyrrolidone to obtain modified graphite with reduced size and better dispersion.Natural pyrite composite polyvinylpyrrolidone-modified graphite(pyrite/PG)material with uniform particle distribution is obtained by the ball milling process.The subsequent calcination process converts pyrite/PG into Fe_(1-x)Scompounded with polyvinylpyrrolidone-modified graphite(Fe_(1-x)S/PG).The homogeneous grain distributions of active material can facilitate the faster transfer of electrons and promote the efficient utilization of active materials.The as-prepared Fe_(1-x)S/PG electrode exhibits a remarkably reversible specific capacity of 613.0 mAh·g^(-1)at 0.2 A·g^(-1)after 80 cycles and an excellent rate capability of 523.0 mAh·g^(-1)at 5 A·g^(-1).Even at a higher current density of 10 A·g^(-1),it can deliver a specific capacity of 348.0 mAh·g^(-1).Moreover,the dominant pseudocapacitance in redox reactions accounts for the impressive rate and cycling stability.This work provides a low-cost and facile method to fabricate natural mineral-based anode materials and apprise readers about the impact of uniform particle distribution on lithium storage performance.展开更多
基金financially supported by the National Natural Science Foundation of China(Grant No.52202328,52372099)the Shanghai Sailing Program(22YF1455500).
文摘Poor Li plating reversibility and high thermal runaway risks are key challenges for fast charging lithiumion batteries with graphite anodes.Herein,a dielectric and fire-resistant separator based on hybrid nanofibers of barium sulfate(BS)and bacterial cellulose(BC)is developed to synchronously enhance the battery's fast charging and thermal-safety performances.The regulation mechanism of the dielectric BS/BC separator in enhancing the Li^(+)ion transport and Li plating reversibility is revealed.(1)The Max-Wagner polarization electric field of the dielectric BS/BC separator can accelerate the desolvation of solvated Li^(+)ions,enhancing their transport kinetics.(2)Moreover,due to the charge balancing effect,the dielectric BS/BC separator homogenizes the electric field/Li^(+)ion flux at the graphite anode-separator interface,facilitating uniform Li plating and suppressing Li dendrite growth.Consequently,the fast-charge graphite anode with the BS/BC separator shows higher Coulombic efficiency(99.0%vs.96.9%)and longer cycling lifespan(100 cycles vs.59 cycles)than that with the polypropylene(PP)separator in the constantlithiation cycling test at 2 mA cm^(-2).The high-loading LiFePO4(15.5 mg cm^(-2))//graphite(7.5 mg cm^(-2))full cell with the BS/BC separator exhibits excellent fast charging performance,retaining 70%of its capacity after 500 cycles at a high rate of 2C,which is significantly better than that of the cell with the PP separator(retaining only 27%of its capacity after 500 cycles).More importantly,the thermally stable BS/BC separator effectively elevates the critical temperature and reduces the heat release rate during thermal runaway,thereby significantly enhancing the battery's safety.
基金Financial support provided by the Australian Research Council(ARC)(grant nos.FT150100109 and LP160101629)is gratefully acknowledged.The authors also acknowledge Dr Tania Silver at the University of Wollongong for editing the English.
文摘Increasing the energy density of conventional lithium-ion batteries(LIBs)is important for satisfying the demands of electric vehicles and advanced electronics.Silicon is considered as one of the most-promising anodes to replace the traditional graphite anode for the realization of high-energy LIBs due to its extremely high theoretical capacity,although its severe volume changes during lithiation/delithiation have led to a big challenge for practical application.In contrast,the co-utilization of Si and graphite has been well recognized as one of the preferred strategies for commercialization in the near future.In this review,we focus on different carbonaceous additives,such as carbon nanotubes,reduced graphene oxide,and pyrolyzed carbon derived from precursors such as pitch,sugars,heteroatom polymers,and so forth,which play an important role in constructing micrometersized hierarchical structures of silicon/graphite/carbon(Si/G/C)composites and tailoring the morphology and surface with good structural stability,good adhesion,high electrical conductivity,high tap density,and good interface chemistry to achieve high capacity and long cycling stability simultaneously.We first discuss the importance and challenge of the co-utilization of Si and graphite.Then,we carefully review and compare the improved effects of various types of carbonaceous materials and their associated structures on the electrochemical performance of Si/G/C composites.We also review the diverse synthesis techniques and treatment methods,which are also significant factors for optimizing Si/G/C composites.Finally,we provide a pertinent evaluation of these forms of carbon according to their suitability for commercialization.We also make far-ranging suggestions with regard to the selection of proper carbonaceous materials and the design of Si/G/C composites for further development.
基金MA and LS are grateful to the Rowe Family Endowment Fund,and QH acknowledges Tang Fellowship.The financial support from the U.S.National Science Foundation(NSF)with the award number CMMI-1660572 is acknowledged.Further,the discussion of TEM images with Dr.Satyanarayana Emani is appreciated.The use of the Center for Nanoscale Materials,an Office of Science user facility,was supported by the U.S.Department of Energy,Office of Science,Office of Basic Energy Sciences,under Contract No.DE-AC02-06CH11357.
文摘Silicon/graphite(Si/Gr)nanocomposites with controlled void spaces and encapsulated by a carbon shell(Si/Gr@void@C)are synthesized by utilizing high-energy ball milling to reduce micron-sized particles to nanoscale,followed by carbonization of polydopamine(PODA)to form a carbon shell,and finally partial etching of the nanostructured Si core by NaOH solution at elevated temperatures.In particular,the effects of ball milling time and NaOH etching temperature on the electrochemical properties of Si/Gr@void@C are investigated.Increasing the ball milling time results in the improved specific capacity of Si-based anodes.Carbon coating further enhances the specific capacity and capacity retention over charge/discharge cycles.The best cycle stability is achieved after partial etching of the Si core inside Si/Gr@void@C particles at either 70 or 80C,leading to little or no capacity decay over 130 cycles.However,it is found that both carbon coating and NaOH etching processes cause some surface oxidation of the nanostructured Si particles derived from high-energy ball milling.The surface oxidation of the nanostructured Si results in decreases in specific capacity and should be minimized in future studies.The mechanistic understanding developed in this study paves the way to further improve the electrochemical performance of Si/Gr@void@C nanocomposites in future.
基金supported by the National Natural Science Foundation of China (No. 22008256)。
文摘Silicon is believed to be a critical anode material for approaching the roadmap of lithium-ion batteries due to its high specific capacity. But this aim has been hindered by the quick capacity fading of its electrodes during repeated charge–discharge cycles. In this work, a “soft-hard”double-layer coating has been proposed and carried out on ball-milled silicon particles. It is composed of inside conductive pathway and outside elastic coating, which is achieved by decomposing a conductive graphite layer on the silicon surface and further coating it with a polymer layer.The incorporation of the second elastic coating on the inside carbon coating enables silicon particles strongly interacted with binders, thereby making the electrodes displaying an obviously improved cycling stability. As-obtained double-coated silicon anodes deliver a reversible capacity of 2280 m Ah g^(-1)at the voltage of 0.05–2 V, and maintains over 1763 mAh g^(-1)after 50 cycles. The double-layer coating does not crack after the repeated cycling, critical for the robust performance of the electrodes. In addition, as-obtained silicon particles are mixed with commercial graphite to make actual anodes for lithium-ion batteries. A capacity of 714 mAh g^(-1)has been achieved based on the total mass of the electrodes containing 10 wt.% double-coated silicon particles. Compared with traditional carbon coating or polymeric coating, the double-coating electrodes display a much better performance. Therefore, the double-coating strategy can give inspiration for better design and synthesis of silicon anodes, as well as other battery materials.
基金supported by the National Natural Science Foundation of China Projects(Nos.52271213,52202299).
文摘Micro-silicon(Si)anode that features high theoretical capacity and fine tap density is ideal for energy-dense lithiumion batteries.However,the substantial localized mechanical strain caused by the large volume expansion often results in electrode disintegration and capacity loss.Herein,a microporous Si anode with the SiO_(x)/C layer functionalized all-surface and high tap density(~0.65 g cm^(-3))is developed by the hydrolysis-driven strategy that avoids the common use of corrosive etchants and toxic siloxane reagents.The functionalized inner pore with superior structural stability can effectively alleviate the volume change and enhance the electrolyte contact.Simultaneously,the outer particle surface forms a continuous network that prevents electrolyte parasitic decomposition,disperses the interface stress of Si matrix and facilitates electron/ion transport.As a result,the micron-sized Si anode shows only~9.94 GPa average stress at full lithiation state and delivers an impressive capacity of 901.1 mAh g^(-1)after 500 cycles at 1 A g^(-1).It also performs excellent rate performance of 1123.0 mAh g^(-1)at 5 A g^(-1)and 850.4 at 8 A g^(-1),far exceeding most of reported literatures.Furthermore,when paired with a commercial LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2),the pouch cell demonstrates high capacity and desirable cyclic performance.
基金supported by the Natural Science Foundation of Ningxia(No.2022AAC05014).
文摘In this work,the Si@reduced graphene oxide/ZrO_(2)(Si@rGO/ZrO_(2))with the shelled structures is prepared for the high-capacity and stable lithium-ion batteries.The shelled structure not only significantly improves the electrical conductivity of the whole electrode,but also protects the inner Si nanoparticles(Si NPs)from rupturing and being damaged by undesired side reactions with the electrolyte.As a result,the Si@rGO/ZrO_(2) anode delivers high initial discharge capacity of 3046 mAh·g^(−1) at 1.0 A·g^(−1).After 100 cycles,it can be maintained at 613 mAh·g^(−1),which is much higher than that of either the pure Si NPs(31 mAh·g^(−1))or the Si@rGO(261 mAh·g^(−1)).Even at 2 A·g^(−1),it still provides superior specific capacity of 834 mAh·g^(−1),while the pure Si anode merely possesses the capacity of 41 mAh·g^(−1).Moreover,the density functional theory calculations point out that ZrO_(2) layer can effectively enhance the adsorption energy of Li+and optimize the migration paths of Li+,ensuring the electrochemical performance of Si@rGO/ZrO_(2) composite anode.Furthermore,the Li+storage mechanism and low volume expansion of Si@rGO/ZrO_(2) anode is investigated by ex-situ X-ray photoelectron spectroscopy and morphological evolution upon cycling,respectively.
基金support from the Open Fund of Jiangsu Key Laboratory of Electrochemical Energy Storage Technologies(No.EEST2019-1).
文摘Severe volume changes and poor electrochemical performance are key barriers to the practical use of silicon anodes.In this study,a self-healing,multifunctional supramolecular binder system was introduced,which combines polymers,ionic liquids,and halometals to achieve dynamic cross linking during volume changes.The addition of specific halometals can adjust the Li+solvation structure and energy,promoting the formation of a stable solid electrolyte interface(SEI)rich in LiF and facilitating Li+desolvation.After 200 cycles,the Si@BF binder(with both ionic liquid and halometal)showed no cracks,indicating excellent structural stability.Additionally,Si||LiFePO_(4)(LFP)full-cell tests at 5 C rate reveal drastic differences:The unmodified binder(the pristine Si)exhibits nearly 0%capacity retention after 400 cycles,the ionic liquid-modified system(Si@B)maintains 11.58%,while Si@BF achieves a remarkable 90.92%retention.Notably,Si@BF retains 78.72%capacity even after 800 cycles.This study offers new insights into dynamic cross-linking systems and solvation-structure regulation,providing references for developing advanced lithium-ion batteries with better performance.
基金the National Natural Science Foundation of China(32201497)for the financial support of this research。
文摘Silicon(Si)is considered one of the most promising anode materials for next-generation lithium-ion batteries due to its ultrahigh theoretical capacity.However,its application is significantly limited by severe volume expansion,leading to structural degradation and poor cycling stability.Polymer binders play a critical role in addressing these issues by providing mechanical stabilization.Inspired by the mechanically adaptive architecture of spider webs,where stiff radial threads and extensible spiral threads act in synergy,a dual-thread architecture polymer binder(PALT)with energy dissipation ability enabled by integrating rigid and flexible domains is designed.The rigid poly(acrylic acid lithium)(PAALi)segments offer structural reinforcement,while the soft segments(poly(lipoic acid-tannic acid),LT)introduce dynamic covalent bonds and multiple hydrogen bonds that function as reversible sacrificial bonds,enhancing energy dissipation during cycling.Comprehensive experimental and computational analyses demonstrate effectively reduced stress concentration,improved structural integrity,and stable electrochemical performance over prolonged cycling.The silicon anode incorporating the PALT binder exhibits a satisfying capacity loss per cycle of 0.042% during 350 charge/discharge cycles at 3580 m A g^(-1).This work highlights a bioinspired binder design strategy that combines intrinsic rigidity with dynamic stress adaptability to advance the mechanical and electrochemical stability of silicon anodes.
基金funding supports of the National Natural Science Foundation of China(52402315,52172244,51874104,and 52172190)the"Leading Innovative and Entrepreneur Team Introduction Program of Zhejiang"(2023R01007)the Zhejiang Provincial"Jianbing"and"Lingyan"R&D Programs(Grant No.2024C01262)。
文摘Polyacrylic acid(PAA)-based binders have been demonstrated to significantly enhance the cycling stability of pure silicon(Si)anodes compared to other binder types.However,there is a notable lack of systematic and in-depth investigation into the relationship between the molecular weight(MW)of PAA and its performance in pure Si anodes,leading to an absence of reliable theoretical guidance for designing and optimizing of PAA-based binders for these anodes.Herein,we select a series of PAA with varying MWs as binders for Si nanoparticle(SiNP)anodes to systematically identify the optimal MW of PAA for enhancing the electrochemical performance of SiNP anodes.The actual MWs of the various PAA were confirmed by gel permeation chromatography to accurately establish the relationship between MW and binder performance.Within an ultrawide weight average molecular weight(M_(w))range of 35.9-4850 kDa,we identify that the PAA binder with a M_(w)of 1250 kDa(PAA125)exhibits the strongest mechanical strength and the highest adhesion strength,attributed to its favorable molecular chain orientation and robust interchain interactions.These characteristics enable the SiNP anodes utilizing PAA125 to maintain the best interfacial chemistry and bulk mechanical structure stability,leading to optimal electrochemical performance.Notably,the enhancement in cycling stability of SiNP anode by PAA125 under practical application conditions is further validated by the 1.1 Ah LLNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)/SiNP@PAA125 pouch cell.
基金the financial support of the National Natural Science Foundation of China(NSFC,No.12074093)。
文摘This study presents a novel approach to enhance silicon anode performance through barium titanate(BTO)incorporation,with the establishment of a force-electric coupling model.By introducing piezoelectric BTO into silicon matrices,we successfully improved both the mechanical stability and electrochemical kinetics of the anode.The developed force-electric coupling model explains how BTO mitigates stress accumulation during lithiation while optimizing the kinetics of Li^(+)and electron transfer.Experimental verification and multiphysical simulation indicate that Si@BTO effectively eliminates structural degradation during the cycling process and significantly reduces the charge transfer resistance.The force-electric coupling mechanism further facilitates stable solid electrolyte interphase(SEI)formation.When paired with LiFePO_(4)cathodes,Si@BTO maintains 76% capacity retention after 500 cycles at a 10 C rate.This work establishes a basic force-electric coupling model framework and offers insights into the development of advanced silicon anode batteries with exceptional performance.
基金supported by the National Natural Science Foundation of China(Grant Nos.12072183,12472174,and 12421002).
文摘The recently reported silicon/graphite(Si/Gr)composite electrode with a layered structure is a promising approach to achieve high capacity and stable cycling of Si-based electrodes in lithium-ion batteries.However,there is still a need to clarify why particular layered structures are effective and why others are ineffective or even detrimental.In this work,an unreported mechanism dominated by the porosity evolution of electrodes is proposed for the degradation behavior of layered Si/Gr electrodes.First,the effect of layering sequence on the overall electrode performance is investigated experimentally,and the results suggest that the cycling performance of the silicon-on-graphite(SG)electrode is much superior to that of the graphite-on-silicon electrode.To explain this phenomenon,a coupled mechanical-electrochemical porous electrode model is developed,in which the porosity is affected by the silicon expansion and the local constraints.The modeling results suggest that the weaker constraint of the silicon layer in the SG electrode leads to a more insignificant decrease in porosity,and consequently,the more stable cycling performance.The findings of this work provide new insights into the structural design of Si-based electrodes.
基金Financial support by the NSFC no. 52371224, 51972156, and 51872131
文摘The intrinsic volume changes(about 300%)of Si anode during the lithiation/delithiation leads to the serious degradation of battery performance despite of theoretical capacity of 3579 mAh g^(-1) of Si.Herein,a three-dimensional(3D)conductive polymer binder with adjustable crosslinking density has been designed by employing citric acid(CA)as a crosslinker between the carboxymethyl cellulose(CMC)and the poly(3,4-ethylenedioxythiophene)poly-(styrene-4-sulfonate)(PEDOT:PSS)to stabilize Si anode.By adjusting the crosslinking density,the binder can achieve a balance between rigidity and flexibility to adapt the volume expansion upon lithiation and reversible volume recovery after delithiation of Si.Therefore,Si/CMC-CA-PEDOT:PSS(Si/CCP)electrode demonstrates an excellent performance with high capacities of 2792.3 mAh g^(-1) at 0.5 A g^(-1) and a high area capacity above 2.6 mAh cm^(-2) under Si loading of 1.38 mg cm^(-2).The full cell Si/CCP paired with Li(Ni_(0.8)Co_(0.1)Mn_(0.1))O_(2) cathode discharges a capacity of 199.0 mAh g^(-1) with 84.3%ICE at 0.1 C and the capacity retention of 95.6%after 100 cycles.This work validates the effectiveness of 3D polymer binder and provides new insights to boost the performance of Si anode.
基金supported by the National Natural Science Foundation of China(No.61904130)the Key Research and Development Program of Hubei Province(Nos.2023BAB122,2021BAA063,and 2020BAB084)the Key Laboratory of Coal Conversion and New Carbon Materials in Hubei Province(No.WKDM201907)for their invaluable support.
文摘Silicon(Si)anodes,with a theoretical specific capacity of 4200 mAh g^(-1),hold significant promise for the development of high-energy-density lithium-ion batteries(LIBs).However,practical applications are hindered by sluggish charge transfer kinetics,substantial volume expansion,and an unstable solid elec-trolyte interphase during cycling.To address these challenges,we propose a centimeter-scale Si anode design featuring a three-dimensional continuous network structure of Si nanowires(SiNWs)decorated with high-density Ag nanoparticles(Ag-SiNWs-Net)on both the surface and internally.This architecture effectively mitigates mechanical stress from Si volume changes through the high-aspect-ratio wire network.Additionally,the distribution of Ag nanoparticles on the Si induces electronic structure redistribution,generating built-in electric fields that accelerate charge transfer within the Si,significantly enhancing rate performance and cycling stability.The Ag-SiNWs-Net anode achieves a high reversible capacity of 3780.9 mAh g^(-1)at 0.1 A g^(-1),with an initial coulombic efficiency of 85.1%.Moreover,the energy density of full cells assembled with Ag-SiNWs-Net anodes and LiFePO4 cathodes can be pushed further up to 395.8 Wh kg^(-1).This study offers valuable insights and methodologies for the development of high-capacity and practical Si anodes-.
基金supported by the Major Science and Technology Projects in Yunnan Province(Grant No.202402AF080005)National Natural Science Foundation of China(Grant Nos.52274408,22468029,52274412)+2 种基金Yunnan Fundamental Research Projects(Grant No.202201AW070014)the Program for Innovative Research Team in University of Ministry of Education of China(Grant No.IRT 17R48)the German Research Foundation(DFG,Project number 501766751).
文摘While silicon/carbon(Si/C)is considered one of the most promising anode materials for the next generation of high-energy lithium-ion batteries(LIBs),the industrialization of Si/C anodes is hampered by high-cost and low product yield.Herein,a high-yield strategy is developed in which photovoltaic waste silicon is converted to cost-effective graphitic Si/C composites(G-Si@C)for LIBs.The introduction of a binder improves the dispersion and compatibility of silicon and graphite,enhances particle sphericity,and significantly reduces the loss rate of the spray prilling process(from about 25%to 5%).As an LIB anode,the fabricated G-Si@C composites exhibit a capacity of 605 mAh g^(-1) after 1200 cycles.The cost of manufacturing Si/C anode materials has been reduced to approximately$7.47 kg^(-1),which is close to that of commercial graphite anode materials($5.0 kg^(-1)),and significantly lower than commercial Si/C materials(ca.$20.74 kg^(-1)).Moreover,the G-Si@C material provides approximately 81.0 Ah/$of capacity,which exceeds the current best commercial graphite anodes(70.0 Ah/$)and Si/C anodes(48.2 Ah/$).The successful implementation of this pathway will significantly promote the industrialization of high-energydensity Si/C anode materials.
基金supported by the Jiangyin-SUSTech Innovation Fundthe National Natural Science Foundation of China (No. 22309078 and 52302261)+3 种基金the Shenzhen Key Laboratory of Advanced Energy Storage (ZDSYS20220401141000001)the Shenzhen Science and Technology Plan Project(No. SGDX20230116091644003)the Guangdong Basic and Applied Basic Research Foundation (2023B1515120069)the Pico Center at SUSTech Core Research Facilities,which is supported by the Presidential Fund and the Development and Reform Commission of Shenzhen Municipality
文摘There is an urgent need to develop high-areal-capacity silicon(Si)anodes with good cycling stability and rate capability for high-energy-density lithium-ion batteries(LIBs).However,this remains a huge challenge due to large volume expansion-induced mechanical degradation and electrical connectivity loss in thick electrodes.Here,a three-in-one strategy is proposed to achieve high-areal-capacity silicon anodes by constructing a multi-level interconnected 3D porous and robust conductive network that carbon nanofibers and vertical carbon nanosheets tightly encapsulate on the surface of Si nanoparticles(Si NPs)anchored in porous carbon felts.This network accommodates large volume expansion of Si NPs to significantly improve electrode mechanical stability and creates excellent electrical connectivity to boost charge transport in thick electrodes,revealed through Multiphysics field simulations and in situ electrochemical techniques.Therefore,the designed Si anodes achieve superior long-term stability with a capacity of 8.13 mAh cm^(-2)after 500 cycles and an ultrahigh areal capacity of 45.8 mAh cm^(-2).In particular,Ah-level pouch cells demonstrate an impressive capacity retention of 79.34%after 500 cycles at 1 C.Our study offers novel insights and directions for understanding and optimizing high-areal-capacity silicon-carbon composite anodes.
基金supported by the Nanxun Scholars Program for Young Scholars of ZJWEU(No.RC2023021315)the start-up funding for Scientific Research for High-level Talents(No.88106324004)the National Natural Science Foundation of China(No.62304070).
文摘Silicon-based materials are considered as the next generation anode to replace graphite due to their low cost and ultra-high theoretical capacity.However,significant volume expansion and contraction occur during charging and discharging processes,leading to the instability of electrode structure and susceptibility to peeling and damage,limiting its application.Constructing controllable molecular artificial solid electrolyte interphase(CMASEI)is an effective approach to address the commercialization of silicon-based anode materials[1].Improving the performance of silicon-based anodes through CMASEI is a multifaceted outcome.
基金supported by the National Natural Science Foundation of China(NSFC No.52172257 and 22005334)the Natural Science Foundation of Beijing(Grant No.Z200013)the National Key Research and Development Program of China(Grant No.2022YFB2502200).
文摘Fast-charging lithium-ion batteries are highly required,especially in reducing the mileage anxiety of the widespread electric vehicles.One of the biggest bottlenecks lies in the sluggish kinetics of the Li^(+)intercalation into the graphite anode;slow intercalation will lead to lithium metal plating,severe side reactions,and safety concerns.The premise to solve these problems is to fully understand the reaction pathways and rate-determining steps of graphite during fast Li^(+)intercalation.Herein,we compare the Li^(+)diffusion through the graphite particle,interface,and electrode,uncover the structure of the lithiated graphite at high current densities,and correlate them with the reaction kinetics and electrochemical performances.It is found that the rate-determining steps are highly dependent on the particle size,interphase property,and electrode configuration.Insufficient Li^(+)diffusion leads to high polarization,incomplete intercalation,and the coexistence of several staging structures.Interfacial Li^(+)diffusion and electrode transportation are the main rate-determining steps if the particle size is less than 10μm.The former is highly dependent on the electrolyte chemistry and can be enhanced by constructing a fluorinated interphase.Our findings enrich the understanding of the graphite structural evolution during rapid Li^(+)intercalation,decipher the bottleneck for the sluggish reaction kinetics,and provide strategic guidelines to boost the fast-charging performance of graphite anode.
文摘We report the synthesis of a high‐performance graphitic carbon‐coated silicon(Si@GC)composite material for lithium‐ion batteries via a scalable production route.Porous Si is produced from the magnesiothermic reduction of commercial silica(SiO2)precursor followed by low‐temperature graphitic carbon coating using glucose as the precursor.The obtained Si@GC composite achieves an excellent reversible specific capacity of 1195 mAh g−1 and outstanding cycle stability.The thick Si@GC anode(3.4 mg cm^−2)in full cells with commercial lithium iron phosphate cathode delivers a remarkable performance of 800 mAh g^−1 specific capacity and 2.7 mAh cm^−2 areal capacity as well as 93.6%capacity retention after 200 cycles.
基金supports from the National Natural Science Foundation of China(51772135,52002115)the Fundamental Research Funds for the Central Universities(21617330)Science and Technology Development Project of Henan Province(212102210487)。
文摘With the increased demand from the storage of renewable energy sources,some safe and inexpensive energy storage technologies instead of Li-ion batteries become urgently needed.Therefore,K-ion batteries(KIBs)have attracted much attention and evolved significant development because of the low price,safety,and similar property compared with Li-ion batteries.Due to the high reversibility,stability,and low potential plateau,graphite becomes a current research focus and is regarded as one of the most promising KIB’s anode materials.In this review,we mainly discuss the electrochemical reaction mechanism of graphite during potassiation-depotassiation process and analyze the effects of electrode/electrolyte interface on graphite for Kion storage.Besides,we summarize several kinds of methods to improve the performance of graphite for KIBs,including the design of graphite structure,selection of appropriate binder,solvent chemistry,and salt chemistry.Meanwhile,a concept of“relative energy density”is raised,which can be more accurate to evaluate the genuine electrochemical performance of graphite anode involving the specific capacity and potential.In addition,we also summarize the considerable challenges to current graphite anode in KIBs and we believe our work will offer alterative solutions to further explore high-performance graphite anode of K-ion storage.
基金financially supported by the National Natural Science Foundation of China (Nos.51974222 and 52034011)。
文摘Natural minerals-based energy materials have attracted enormous attention because of the advantages of good materials consistency,high production,environmental friendliness,and low cost.The uniform distribution of grains can effectively inhibit the aggregation of active materials,improving lithium storage performance.In this work,natural graphite is modified by polyvinylpyrrolidone to obtain modified graphite with reduced size and better dispersion.Natural pyrite composite polyvinylpyrrolidone-modified graphite(pyrite/PG)material with uniform particle distribution is obtained by the ball milling process.The subsequent calcination process converts pyrite/PG into Fe_(1-x)Scompounded with polyvinylpyrrolidone-modified graphite(Fe_(1-x)S/PG).The homogeneous grain distributions of active material can facilitate the faster transfer of electrons and promote the efficient utilization of active materials.The as-prepared Fe_(1-x)S/PG electrode exhibits a remarkably reversible specific capacity of 613.0 mAh·g^(-1)at 0.2 A·g^(-1)after 80 cycles and an excellent rate capability of 523.0 mAh·g^(-1)at 5 A·g^(-1).Even at a higher current density of 10 A·g^(-1),it can deliver a specific capacity of 348.0 mAh·g^(-1).Moreover,the dominant pseudocapacitance in redox reactions accounts for the impressive rate and cycling stability.This work provides a low-cost and facile method to fabricate natural mineral-based anode materials and apprise readers about the impact of uniform particle distribution on lithium storage performance.
