The progress of the Separated Function RFQ (SFRFQ) accelerator, which can raise the field gradient of acceleration while maintaining the transverse focusing power sufficient for high current beam, is presented. In ord...The progress of the Separated Function RFQ (SFRFQ) accelerator, which can raise the field gradient of acceleration while maintaining the transverse focusing power sufficient for high current beam, is presented. In order to demonstrate the feasibilities of the novel accelerator, a prototype cavity was designed and constructed. Correspondingly, a code SFRFQCODEV1.0 was developed specially for cavity design and beam dynamics simulation. The prototype cavity will be verified as a post-accelerator for ISR RFQ-1000 (Integral Split Ring RFQ) and accelerate O+ from 1 MeV to 1.6 MeV. To inject a higher current oxygen beam for the prototype cavity, the beam current of ISR RFQ-1000 was upgraded to 2 mA. The status of high power and beam test preparation for the prototype cavity are presented in this paper.展开更多
Shuttle effect of polysulfides overshadows the superiorities of lithium-sulfur batteries.Size-sieving effect could address this thorny trouble rely on size differ in polysulfides and lithium ions.However,clogged polys...Shuttle effect of polysulfides overshadows the superiorities of lithium-sulfur batteries.Size-sieving effect could address this thorny trouble rely on size differ in polysulfides and lithium ions.However,clogged polysulfides pose some challenges for cathode and are rarely recycled during charging/discharging.Herein,an amino functionalized titanium-organic framework is designed for modifying lithium-sulfur batteries separator to address the aforementioned challenges.Wherein,the introduction of amino narrows titanium-organic framework pore size,enabling functional separator to selectively modulate lithium ions and polysulfides migration using size-sieving effect,thereby completely suppressing polysulfides shuttle.Furthermore,the blocked polysulfides will be adsorbed on the separator surface by positively charged amino leveraging electrostatic adsorption,ensuring polysulfides to redistribute and reuse,and boosting active materials utilization.Significantly,the migration of lithium ions is not hindered since there are lithium ions transfer channels formed via Lewis acid-base interaction with the help of amino.Combined with these virtues,the lithium-sulfur batteries with amino functionalized titanium-organic framework modified separator enjoy an ultralow attenuation rate of 0.045%per cycle over 1000 cycles at 1.0C.Electrostatic adsorption and Lewis acid-base interaction cover deficiencies existing in the inhibition of polysulfides shuttle by size-sieving effect,providing fresh insight into the advancement of lithium-sulfur batteries.展开更多
Lithium–sulfur(Li-S)batteries have the advantages of high theoretical specific capacity(1675 mAh g^(−1)),rich sulfur resources,low production cost,and friendly environment,which makes it one of the most promising nex...Lithium–sulfur(Li-S)batteries have the advantages of high theoretical specific capacity(1675 mAh g^(−1)),rich sulfur resources,low production cost,and friendly environment,which makes it one of the most promising next-generation rechargeable energy storage devices.However,the“shuttle effect”of polysulfide results in the passivation of metal lithium anode,the decrease of battery capacity and coulombic efficiency,and the deterioration of cycle stability.To realize the commercialization of Li-S batteries,its serious“shuttle effect”needs to be suppress.The commercial separators are ineffective to suppress this effect because of its large pore size.Therefore,it is an effective strategy to modify the separator surface and introduce functional modified layer.In addition to the blocking strategy,the catalysis of polysulfide conversion reaction is also an important factor hindering the migration of polysulfides.In this review,the principles of separator modification,functionalization,and catalysis in Li-S batteries are reviewed.Furthermore,the research trend of separator functionalization and polysulfide catalysis in the future is prospected.展开更多
Generalized functional separation of variables to nonlinear evolution equations is studied in terms of the extended group foliation method, which is based on the Lie point symmetry method. The approach is applied to n...Generalized functional separation of variables to nonlinear evolution equations is studied in terms of the extended group foliation method, which is based on the Lie point symmetry method. The approach is applied to nonlinear wave equations with variable speed and external force. A complete classification for the wave equation which admits functional separable solutions is presented. Some known results can be recovered by this approach.展开更多
Lithium metal batteries(LMBs)have attracted wide attentions because of their high theoretical specific capacity and low electrochemical potential.However,the growth of lithium dendrites seriously affects the practical...Lithium metal batteries(LMBs)have attracted wide attentions because of their high theoretical specific capacity and low electrochemical potential.However,the growth of lithium dendrites seriously affects the practical application of LMBs.Thus,the lithium-philic carbonyl and carboxy dualgroup-modified covalent organic framework(COF-COOH)is designed to coat the polypropylene(PP)separator(COF-COOH@PP separator),realizing the regulation of ion transport and uniform lithium deposition.The plentiful and negative charge sites in the COF-COOH can suppress the diffusion of the freely movable lithium salt anion by the electrostatic interaction.Density functional theory(DFT)calculations demonstrate that the COF-COOH possesses the function of anchoring anion and desolvation.Consequently,the Li^(+)transference number(0.7),ion conductivity(0.64 mS cm^(-1)),and desolvating of Li^(+)are obviously improved by using the COF-COOH@PP separator.The modified Li-Li symmetric battery delivers stable cycle for more than 1000 h and lower voltage hysteresis(0.02 V).This dendrite-free deposition strategy holds great promise for practical application of Li metal anodes.展开更多
We consider the functional separation of variables to the nonlinear diffusion equation with source and convection term： ut = （A（x）D（u）ux）x ＋ B（x）Q（u）, Ax ≠ 0. The functional separation of variables to thi...We consider the functional separation of variables to the nonlinear diffusion equation with source and convection term： ut = （A（x）D（u）ux）x ＋ B（x）Q（u）, Ax ≠ 0. The functional separation of variables to this equation is studied by using the group foliation method. A classification is carried out for the equations which admit the function separable solutions. As a consequence, some solutions to the resulting equations are obtained.展开更多
Lithium-sulfur(Li-S)batteries are receiving increasing attention as one of the potential next-generation batteries,owing to their high energy densities and low cost.However,practical Li-S batteries with high energy de...Lithium-sulfur(Li-S)batteries are receiving increasing attention as one of the potential next-generation batteries,owing to their high energy densities and low cost.However,practical Li-S batteries with high energy densities are extremely hindered by the sulfur loss,low Coulombic efficiency,and short cycling life originating from the polysulfide(LiPS)shuttle.In this study,two-dimensional(2D)ZnCo_(2)O_(4) microsheets fabricated by a facile hydrothermal process are employed to modify the separator,for improving the electrochemical performances of Li-S cells.The resulting 2D Zn Co_(2)O_(4)-coated separator features a coating thickness of approximately 10 lm,high ionic conductivity of 1.8 m S/cm,and low mass loading of 0.2 mg/cm^(2).This 2D ZnCo_(2)O_(4)-coated separator effectively inhibits Li PS shuttle by a strong chemical interaction with Li PS as well as promotes the redox kinetics by Zn CO2O4-coated layers,as determined by X-ray photoelectron spectroscopy analysis,self-discharge,time-dependent permeation test,Li symmetric cell test,and Li2S nucleation analyses.Consequently,the Li-S batteries based on the 2D Zn Co_(2)O_(4)-coated separator exhibit a high initial discharge capacity of 1292.2 m Ah/g at 0.1 C.Moreover,they exhibit excellent long cycle stability at 1 and 2 C with capacity retention of 84%and 86%even after800 cycles,corresponding to a capacity fading rate of 0.020%and 0.016%per cycle,respectively.Effectively,these Li-S cells with a high sulfur loading at 5.3 mg/cm^(2) and low electrolyte concentration of 9 l L/mg deliver a high discharge capacity of 4.99 m Ah/cm^(2) after 200 cycles at 0.1 C.展开更多
Using the generalized conditional symmetry approach, we obtain a number of new generalized (1+1)-dimensional nonlinear wave equations that admit derivative-dependent functional separable solutions.
This paper is devoted to the study of functional variable separation for extended nonlinear elliptic equations. By applying the functional variable separation approach to extended nonlinear elliptic equations via the ...This paper is devoted to the study of functional variable separation for extended nonlinear elliptic equations. By applying the functional variable separation approach to extended nonlinear elliptic equations via the generalized conditional symmetry, we obtain complete classification of those equations which admit functional separable solutions （FSSs） and construct some exact FSSs to the resulting equations.展开更多
The lithium-sulfur(Li-S)battery,as one of the energy storage devices,has been in the limelight due to its high theoretical energy density.However,the poor redox kinetics and the"shuttle effect"of polysulfide...The lithium-sulfur(Li-S)battery,as one of the energy storage devices,has been in the limelight due to its high theoretical energy density.However,the poor redox kinetics and the"shuttle effect"of polysulfides severely restrict the use of Li-S batteries in practical applications.Herein,a novel bimetallic LaNiO_(3) functional material with high electrical conductivity and catalytic property is prepared to act as a high-efficiency polysulfide shuttling stopper.The three LaNiO_(3) samples with different physical/chemical characteristics are obtained by controlling the calcination temperature.In conjunction with the high electrical conductivity and excellent catalytic properties of the as-prepared materials,the appropriate chemisorption toward polysulfides offers great potential to enhance electrochemical stability for highperformance Li-S batteries.Particularly,the Li-S cell with the separator modified by such functional material gives a specific capacity of 658 mA h g^(-1) after 500 cycles at a high current density of 2 C.Even with high sulfur loading of 6.05 mg cm^(-2),the Li-S battery still exhibits an areal specific capacity of 2.81 m A h cm^(-2)after 150 cycles.This work paves a new avenue for the rational design of materials for separator modification in high-performance Li-S batteries.展开更多
This paper studies variable separation of the evolution equations via the generalized conditional symmetry. To illustrate, we classify the extended nonlinear wave equation utt = A（u, ux）uxx＋B（u, ux, ut） which adm...This paper studies variable separation of the evolution equations via the generalized conditional symmetry. To illustrate, we classify the extended nonlinear wave equation utt = A（u, ux）uxx＋B（u, ux, ut） which admits the derivative- dependent functional separable solutions （DDFSSs）. We also extend the concept of the DDFSS to cover other variable separation approaches.展开更多
Severe performance drop and fire risk due to the uneven lithium(Li) dendrite formation and growth during charge/discharge process has been considered as the major obstacle to the practical application of Li metal batt...Severe performance drop and fire risk due to the uneven lithium(Li) dendrite formation and growth during charge/discharge process has been considered as the major obstacle to the practical application of Li metal batteries.So inhibiting dendrite growth and producing a stable and robust solid electrolyte interface(SEI) layer are essential to enable the use of Li metal anodes.In this work,a functional lithiophilic polymer composed of chitosan(CTS),polyethylene oxide(PEO),and poly(triethylene glycol dimethacrylate)(PTEGDMA),was homogeneously deposited on a commercial Celgard separator by combining electrospraying and polymer photopolymerization techniques.The lithiophilic environment offered by the CTS-PEO-PTEGDMA layer enables uniform Li deposition and facilitates the formation of a robust homogeneous SEI layer,thus prevent the formation and growth of Li dendrites.As a result,both Li/Li symmetric cells and LiFePO4/Li full cells deliver significantly enhanced electrochemical performance and cycle life.Even after 1000 cycles,the specific capacity of the modified full cell could be maintained at65.8 mAh g^(-1), twice which of the unmodified cell(32.8 mAh g^(-1)).The long-term cycling stability in Li/Li symmetric cells,dendrite-free anodes in SEM images and XPS analysis suggest that the pulverization of the Li anode was effectively suppressed by the lithiophilic polymer layer.展开更多
The generalized conditional symmetry approach is applied to study the variable separation of the extended wave equations. Complete classification of those equations admitting functional separable solutions is obtained...The generalized conditional symmetry approach is applied to study the variable separation of the extended wave equations. Complete classification of those equations admitting functional separable solutions is obtained and exact separable solutions to some of the resulting equations are constructed.展开更多
Lithium-rich manganese-based materials(LRMs) are promising cathode for high-energy-density lithiumion batteries due to their high capacity,low toxicity,and low cost.However,LRMs suffer from serious voltage decay and c...Lithium-rich manganese-based materials(LRMs) are promising cathode for high-energy-density lithiumion batteries due to their high capacity,low toxicity,and low cost.However,LRMs suffer from serious voltage decay and capacity fade due to continual migration and dissolution of transition metal ions(TMs) during cycling process.Herein,a novel strategy is proposed to inhibit the TMs migration of LRMs through a modified separator by means of functionalized carbon coating layer,which depends on the chemical constraint of the abundant functional groups in the modified super P.In addition,it has been found that the dissolution of TMs can be restrained based on the Le Chatelier's principle.Moreover,the modified separator owns good wettability toward the electrolyte.As a result,the LRMs cathode with the modified separator delivers a high discharge capacity of 329.93 mA h g-1 at 0.1 C,and achieves good cyclic performance,the enhanced reaction kinetics and low voltage decay.Therefore,this work provides a new idea to promote the comprehensive electrochemical performances of Li-ion batteries with LRMs cathode through a strategy of separator modification.展开更多
Invariant subspace method is exploited to obtain exact solutions of the two- component b-family system. It is shown that the two-component b-family system admits the generalized functional separable solutions. Further...Invariant subspace method is exploited to obtain exact solutions of the two- component b-family system. It is shown that the two-component b-family system admits the generalized functional separable solutions. Furthermore, blow up and behavior of those exact solutions are also investigated.展开更多
We study the functional separation of variables to the nonlinear heat equation： ut = （A（x）D（u）ux^n）x＋ B（x）Q（u）, Ax≠0. Such equation arises from non-Newtonian fluids. Its functional separation of variables...We study the functional separation of variables to the nonlinear heat equation： ut = （A（x）D（u）ux^n）x＋ B（x）Q（u）, Ax≠0. Such equation arises from non-Newtonian fluids. Its functional separation of variables is studied by using the group foliation method. A classification of the equation which admits the functional separable solutions is performed. As a consequence, some solutions to the resulting equations are obtained.展开更多
According to a statistic,approximately 6 trillion cigarettes are smoked each year all over the world,which produces approximately 1.2 million tons of discarded cigarette butts.The discarded cigarette filters are non-b...According to a statistic,approximately 6 trillion cigarettes are smoked each year all over the world,which produces approximately 1.2 million tons of discarded cigarette butts.The discarded cigarette filters are non-biodegradable,thus they produce a mass of waste disposal and cause environmental pollution is-sue.For the purpose of transforming waste into wealth and reducing environmental pollution,nitrogen and sulfur co-doped carbon nanofiber/carbon black(N,S-CNF/CB)composite derived from the discarded cigarette filters is employed to modify glass fiber(GF)separator for the first time in this study.N,S-CNF improves binding ability towards sodium polysulfides(SPSs)by chemisorption.Non-polar CB limits the dissolution of SPSs in the liquid electrolyte by physisorption.The experiment and density functional theory calculation results indicate that a RT-Na/S battery with a N,S-CNF/CB+GF separator exhibits good cycling stability and rate performance.After 100 cycles at a low current rate of 0.1 C,a RT-Na/S battery with a sulfur mass fraction of 71%delivers a discharge capacity of 703 mAh g^(−1).In addition,at a high current rate of 0.5 C,a discharge capacity of 527 mAh g^(−1) is still maintained after 900 cycles with a very low capacity fading rate of 0.035%per cycle.展开更多
As an extension to the derivative-dependent functional variable separation approach, the approximate derivative-dependent functional variable separation approach is proposed, and it is applied to study the generalized...As an extension to the derivative-dependent functional variable separation approach, the approximate derivative-dependent functional variable separation approach is proposed, and it is applied to study the generalized diffusion equations with perturbation. Complete classification of these perturbed equations which admit approximate derivative-dependent functional separable solutions is obtained. As a result, the corresponding approximate derivative-dependent functional separable solutions to some resulting perturbed equations are derived by way of examples.展开更多
The detrimental“shuttle effect”of lithium polysulfides(LiPSs)together with sluggish multi-order reaction kinetics are the main drawbacks hindering lithium-sulfur(Li-S)batteries from commercial success.Here,we first ...The detrimental“shuttle effect”of lithium polysulfides(LiPSs)together with sluggish multi-order reaction kinetics are the main drawbacks hindering lithium-sulfur(Li-S)batteries from commercial success.Here,we first propose the implementability of layered rare-earth hydroxides(LREHs)in Li-S batteries to optimize electrochemical performance.In this work,a two-dimensional(2D)rare-earth-based composite constructed by the layered gadolinium hydroxy chloride[Gd_(2)(OH)_(5)(H_(2)O)_(n)]Cl nanoplates(LGdH NPs)and graphene oxide(GO)was designed as a sulfur immobilizer for Li-S batteries.Combining the experimental results and density functional theory(DFT)calculations,it is revealed that the LGdH@GO composite not only provides a strong anchoring of the intermediates during cycling,but also acts as an effective catalyst to accelerate the liquid-solid conversion of polysulfides.The Li-S batteries assembled by LGdH@GO modified separators delivered a superior rate performance with a specific capacity of 605.34 mAh/g at 5 C,as well as excellent cycle stability with a decay rate of 0.087%over 500 cycles at 2 C.This study provided a deep understanding of the mechanism to suppress the“shuttle effect”by the LREHs,and a guide to design effective functional interlayers for high-performance Li-S batteries with excellent electrocatalytic activity.展开更多
By using the approximate derivative-dependent functional variable separation approach, we study the quasi-linear diffusion equations with a weak source ut = （A（u）Ux）x ＋ eB（u, Ux）. A complete classification of t...By using the approximate derivative-dependent functional variable separation approach, we study the quasi-linear diffusion equations with a weak source ut = （A（u）Ux）x ＋ eB（u, Ux）. A complete classification of these perturbed equations which admit approximate derivative-dependent functional separable solutions is listed. As a consequence, some approxi- mate solutions to the resulting perturbed equations are constructed via examples.展开更多
基金Supported by National Natural Science Foundation of China (10455001)
文摘The progress of the Separated Function RFQ (SFRFQ) accelerator, which can raise the field gradient of acceleration while maintaining the transverse focusing power sufficient for high current beam, is presented. In order to demonstrate the feasibilities of the novel accelerator, a prototype cavity was designed and constructed. Correspondingly, a code SFRFQCODEV1.0 was developed specially for cavity design and beam dynamics simulation. The prototype cavity will be verified as a post-accelerator for ISR RFQ-1000 (Integral Split Ring RFQ) and accelerate O+ from 1 MeV to 1.6 MeV. To inject a higher current oxygen beam for the prototype cavity, the beam current of ISR RFQ-1000 was upgraded to 2 mA. The status of high power and beam test preparation for the prototype cavity are presented in this paper.
基金supported by the National Natural Science Foundation of China(52463013 and 52073133)Key Talent Project Foundation of Gansu Province+3 种基金Joint fund between Shenyang National Laboratory for Materials ScienceState Key Laboratory of Advanced Processing and Recycling of Nonferrous Metals(18LHPY002)the Program for Hongliu Distinguished Young Scholars in Lanzhou University of Technologythe Incubation Program of Excellent Doctoral Dissertation–Lanzhou University of Technology
文摘Shuttle effect of polysulfides overshadows the superiorities of lithium-sulfur batteries.Size-sieving effect could address this thorny trouble rely on size differ in polysulfides and lithium ions.However,clogged polysulfides pose some challenges for cathode and are rarely recycled during charging/discharging.Herein,an amino functionalized titanium-organic framework is designed for modifying lithium-sulfur batteries separator to address the aforementioned challenges.Wherein,the introduction of amino narrows titanium-organic framework pore size,enabling functional separator to selectively modulate lithium ions and polysulfides migration using size-sieving effect,thereby completely suppressing polysulfides shuttle.Furthermore,the blocked polysulfides will be adsorbed on the separator surface by positively charged amino leveraging electrostatic adsorption,ensuring polysulfides to redistribute and reuse,and boosting active materials utilization.Significantly,the migration of lithium ions is not hindered since there are lithium ions transfer channels formed via Lewis acid-base interaction with the help of amino.Combined with these virtues,the lithium-sulfur batteries with amino functionalized titanium-organic framework modified separator enjoy an ultralow attenuation rate of 0.045%per cycle over 1000 cycles at 1.0C.Electrostatic adsorption and Lewis acid-base interaction cover deficiencies existing in the inhibition of polysulfides shuttle by size-sieving effect,providing fresh insight into the advancement of lithium-sulfur batteries.
基金support of the National Natural Science Foundation of China(No.21773188,No.22179109)central universities fundamental research fund(XDJK2019AA002)Chongqing Natural Science fund(cstc2020jcyj-bshx0047,cstc2021jcyj-bsh0173).
文摘Lithium–sulfur(Li-S)batteries have the advantages of high theoretical specific capacity(1675 mAh g^(−1)),rich sulfur resources,low production cost,and friendly environment,which makes it one of the most promising next-generation rechargeable energy storage devices.However,the“shuttle effect”of polysulfide results in the passivation of metal lithium anode,the decrease of battery capacity and coulombic efficiency,and the deterioration of cycle stability.To realize the commercialization of Li-S batteries,its serious“shuttle effect”needs to be suppress.The commercial separators are ineffective to suppress this effect because of its large pore size.Therefore,it is an effective strategy to modify the separator surface and introduce functional modified layer.In addition to the blocking strategy,the catalysis of polysulfide conversion reaction is also an important factor hindering the migration of polysulfides.In this review,the principles of separator modification,functionalization,and catalysis in Li-S batteries are reviewed.Furthermore,the research trend of separator functionalization and polysulfide catalysis in the future is prospected.
文摘Generalized functional separation of variables to nonlinear evolution equations is studied in terms of the extended group foliation method, which is based on the Lie point symmetry method. The approach is applied to nonlinear wave equations with variable speed and external force. A complete classification for the wave equation which admits functional separable solutions is presented. Some known results can be recovered by this approach.
基金financial support provided by the National Natural Science Foundation of China(52064049)the Key National Natural Science Foundation of Yunnan Province(2018FA028 and 2019FY003023)+2 种基金International Joint Research Center for Advanced Energy Materials of Yunnan Province(202003AE140001)Key Laboratory of Solid State Ions for Green Energy of Yunnan University(2019)the Analysis and Measurements Center of Yunnan University for the sample testing service.
文摘Lithium metal batteries(LMBs)have attracted wide attentions because of their high theoretical specific capacity and low electrochemical potential.However,the growth of lithium dendrites seriously affects the practical application of LMBs.Thus,the lithium-philic carbonyl and carboxy dualgroup-modified covalent organic framework(COF-COOH)is designed to coat the polypropylene(PP)separator(COF-COOH@PP separator),realizing the regulation of ion transport and uniform lithium deposition.The plentiful and negative charge sites in the COF-COOH can suppress the diffusion of the freely movable lithium salt anion by the electrostatic interaction.Density functional theory(DFT)calculations demonstrate that the COF-COOH possesses the function of anchoring anion and desolvation.Consequently,the Li^(+)transference number(0.7),ion conductivity(0.64 mS cm^(-1)),and desolvating of Li^(+)are obviously improved by using the COF-COOH@PP separator.The modified Li-Li symmetric battery delivers stable cycle for more than 1000 h and lower voltage hysteresis(0.02 V).This dendrite-free deposition strategy holds great promise for practical application of Li metal anodes.
基金The project supported by National Natural Science Foundation of China under Grant No. 10371098 and the Program for New Century Excellent Talents in Universities under Grant No. NCET-04-0968
文摘We consider the functional separation of variables to the nonlinear diffusion equation with source and convection term： ut = （A（x）D（u）ux）x ＋ B（x）Q（u）, Ax ≠ 0. The functional separation of variables to this equation is studied by using the group foliation method. A classification is carried out for the equations which admit the function separable solutions. As a consequence, some solutions to the resulting equations are obtained.
基金supported by a grant from R&D Program of the Korea Railroad Research Institute,Republic of Korea。
文摘Lithium-sulfur(Li-S)batteries are receiving increasing attention as one of the potential next-generation batteries,owing to their high energy densities and low cost.However,practical Li-S batteries with high energy densities are extremely hindered by the sulfur loss,low Coulombic efficiency,and short cycling life originating from the polysulfide(LiPS)shuttle.In this study,two-dimensional(2D)ZnCo_(2)O_(4) microsheets fabricated by a facile hydrothermal process are employed to modify the separator,for improving the electrochemical performances of Li-S cells.The resulting 2D Zn Co_(2)O_(4)-coated separator features a coating thickness of approximately 10 lm,high ionic conductivity of 1.8 m S/cm,and low mass loading of 0.2 mg/cm^(2).This 2D ZnCo_(2)O_(4)-coated separator effectively inhibits Li PS shuttle by a strong chemical interaction with Li PS as well as promotes the redox kinetics by Zn CO2O4-coated layers,as determined by X-ray photoelectron spectroscopy analysis,self-discharge,time-dependent permeation test,Li symmetric cell test,and Li2S nucleation analyses.Consequently,the Li-S batteries based on the 2D Zn Co_(2)O_(4)-coated separator exhibit a high initial discharge capacity of 1292.2 m Ah/g at 0.1 C.Moreover,they exhibit excellent long cycle stability at 1 and 2 C with capacity retention of 84%and 86%even after800 cycles,corresponding to a capacity fading rate of 0.020%and 0.016%per cycle,respectively.Effectively,these Li-S cells with a high sulfur loading at 5.3 mg/cm^(2) and low electrolyte concentration of 9 l L/mg deliver a high discharge capacity of 4.99 m Ah/cm^(2) after 200 cycles at 0.1 C.
基金The project supported by the National Outstanding Youth Foundation of China (No.19925522)+2 种基金the Research Fund for the Doctoral Program of Higher Education of China (Grant.No.2000024832)National Natural Science Foundation of China (No.90203001)
文摘Using the generalized conditional symmetry approach, we obtain a number of new generalized (1+1)-dimensional nonlinear wave equations that admit derivative-dependent functional separable solutions.
基金The project supported by National Natural Science Foundation of China under Grant No. 10447007 and the Natural Science Foundation of Shaanxi Province of China under Grant No. 2005A13
文摘This paper is devoted to the study of functional variable separation for extended nonlinear elliptic equations. By applying the functional variable separation approach to extended nonlinear elliptic equations via the generalized conditional symmetry, we obtain complete classification of those equations which admit functional separable solutions （FSSs） and construct some exact FSSs to the resulting equations.
基金supported by the National Natural Science Foundation of China(51972184,22005169)the Key Basic Research Project of Shandong Province(ZR2019ZD49)+2 种基金the Natural Science Foundation of Shandong Province(ZR2020QB121)the Taishan Scholars Project of Shandong Provincethe Taishan Scholar Young Talent Program(tsqn201909114)。
文摘The lithium-sulfur(Li-S)battery,as one of the energy storage devices,has been in the limelight due to its high theoretical energy density.However,the poor redox kinetics and the"shuttle effect"of polysulfides severely restrict the use of Li-S batteries in practical applications.Herein,a novel bimetallic LaNiO_(3) functional material with high electrical conductivity and catalytic property is prepared to act as a high-efficiency polysulfide shuttling stopper.The three LaNiO_(3) samples with different physical/chemical characteristics are obtained by controlling the calcination temperature.In conjunction with the high electrical conductivity and excellent catalytic properties of the as-prepared materials,the appropriate chemisorption toward polysulfides offers great potential to enhance electrochemical stability for highperformance Li-S batteries.Particularly,the Li-S cell with the separator modified by such functional material gives a specific capacity of 658 mA h g^(-1) after 500 cycles at a high current density of 2 C.Even with high sulfur loading of 6.05 mg cm^(-2),the Li-S battery still exhibits an areal specific capacity of 2.81 m A h cm^(-2)after 150 cycles.This work paves a new avenue for the rational design of materials for separator modification in high-performance Li-S batteries.
基金Project supported by the National Natural Science Foundation of China （Grant Nos 10371098, 10447007 and 10475055）, the Natural Science Foundation of Shaanxi Province of China （Grant No 2005A13）.
文摘This paper studies variable separation of the evolution equations via the generalized conditional symmetry. To illustrate, we classify the extended nonlinear wave equation utt = A（u, ux）uxx＋B（u, ux, ut） which admits the derivative- dependent functional separable solutions （DDFSSs）. We also extend the concept of the DDFSS to cover other variable separation approaches.
基金supported by the Natural Science Foundation of Jiangsu Province (BK20170237)National Natural Science Foundation of China (21808094 and 51871113)+1 种基金Key Research and Development Program of Xuzhou (KC17004)Startup Funding for Introduced Talents of Jiangsu Normal University (16XLR015)。
文摘Severe performance drop and fire risk due to the uneven lithium(Li) dendrite formation and growth during charge/discharge process has been considered as the major obstacle to the practical application of Li metal batteries.So inhibiting dendrite growth and producing a stable and robust solid electrolyte interface(SEI) layer are essential to enable the use of Li metal anodes.In this work,a functional lithiophilic polymer composed of chitosan(CTS),polyethylene oxide(PEO),and poly(triethylene glycol dimethacrylate)(PTEGDMA),was homogeneously deposited on a commercial Celgard separator by combining electrospraying and polymer photopolymerization techniques.The lithiophilic environment offered by the CTS-PEO-PTEGDMA layer enables uniform Li deposition and facilitates the formation of a robust homogeneous SEI layer,thus prevent the formation and growth of Li dendrites.As a result,both Li/Li symmetric cells and LiFePO4/Li full cells deliver significantly enhanced electrochemical performance and cycle life.Even after 1000 cycles,the specific capacity of the modified full cell could be maintained at65.8 mAh g^(-1), twice which of the unmodified cell(32.8 mAh g^(-1)).The long-term cycling stability in Li/Li symmetric cells,dendrite-free anodes in SEM images and XPS analysis suggest that the pulverization of the Li anode was effectively suppressed by the lithiophilic polymer layer.
文摘The generalized conditional symmetry approach is applied to study the variable separation of the extended wave equations. Complete classification of those equations admitting functional separable solutions is obtained and exact separable solutions to some of the resulting equations are constructed.
基金supported financially by the National Natural Science Foundation of China (U19A2018)the Key Project of Strategic New Industry of Hunan Province (2019GK2032)+2 种基金the Natural Science Foundation of Hunan Province (2021JJ30651)the Science and Technology Program of Xiangtan (GX-ZD20211004)Postgraduate Scientific Research Innovation Project of Hunan Province (CX20210635)。
文摘Lithium-rich manganese-based materials(LRMs) are promising cathode for high-energy-density lithiumion batteries due to their high capacity,low toxicity,and low cost.However,LRMs suffer from serious voltage decay and capacity fade due to continual migration and dissolution of transition metal ions(TMs) during cycling process.Herein,a novel strategy is proposed to inhibit the TMs migration of LRMs through a modified separator by means of functionalized carbon coating layer,which depends on the chemical constraint of the abundant functional groups in the modified super P.In addition,it has been found that the dissolution of TMs can be restrained based on the Le Chatelier's principle.Moreover,the modified separator owns good wettability toward the electrolyte.As a result,the LRMs cathode with the modified separator delivers a high discharge capacity of 329.93 mA h g-1 at 0.1 C,and achieves good cyclic performance,the enhanced reaction kinetics and low voltage decay.Therefore,this work provides a new idea to promote the comprehensive electrochemical performances of Li-ion batteries with LRMs cathode through a strategy of separator modification.
基金supported by NSFC(11471260)the Foundation of Shannxi Education Committee(12JK0850)
文摘Invariant subspace method is exploited to obtain exact solutions of the two- component b-family system. It is shown that the two-component b-family system admits the generalized functional separable solutions. Furthermore, blow up and behavior of those exact solutions are also investigated.
基金National Natural Science Foundation of China under Grant No.10671156the Program for New Century Excellent Talents in Universities under Grant No.NCET-04-0968
文摘We study the functional separation of variables to the nonlinear heat equation： ut = （A（x）D（u）ux^n）x＋ B（x）Q（u）, Ax≠0. Such equation arises from non-Newtonian fluids. Its functional separation of variables is studied by using the group foliation method. A classification of the equation which admits the functional separable solutions is performed. As a consequence, some solutions to the resulting equations are obtained.
基金supported by the National Natural Science Foundation of China(Nos.51631004 and 52130101)the Basic Construction Fund in Jilin Province Budget for 2019(No.2019C042-8).
文摘According to a statistic,approximately 6 trillion cigarettes are smoked each year all over the world,which produces approximately 1.2 million tons of discarded cigarette butts.The discarded cigarette filters are non-biodegradable,thus they produce a mass of waste disposal and cause environmental pollution is-sue.For the purpose of transforming waste into wealth and reducing environmental pollution,nitrogen and sulfur co-doped carbon nanofiber/carbon black(N,S-CNF/CB)composite derived from the discarded cigarette filters is employed to modify glass fiber(GF)separator for the first time in this study.N,S-CNF improves binding ability towards sodium polysulfides(SPSs)by chemisorption.Non-polar CB limits the dissolution of SPSs in the liquid electrolyte by physisorption.The experiment and density functional theory calculation results indicate that a RT-Na/S battery with a N,S-CNF/CB+GF separator exhibits good cycling stability and rate performance.After 100 cycles at a low current rate of 0.1 C,a RT-Na/S battery with a sulfur mass fraction of 71%delivers a discharge capacity of 703 mAh g^(−1).In addition,at a high current rate of 0.5 C,a discharge capacity of 527 mAh g^(−1) is still maintained after 900 cycles with a very low capacity fading rate of 0.035%per cycle.
基金Supported by the National Natural Science Foundation of China under Grant No.10671156the Natural Science Foundation of Shaanxi Province of China under Grant No.SJ08A05
文摘As an extension to the derivative-dependent functional variable separation approach, the approximate derivative-dependent functional variable separation approach is proposed, and it is applied to study the generalized diffusion equations with perturbation. Complete classification of these perturbed equations which admit approximate derivative-dependent functional separable solutions is obtained. As a result, the corresponding approximate derivative-dependent functional separable solutions to some resulting perturbed equations are derived by way of examples.
基金supported by National Science Foundation for Youths of China(Nos.22209184 and 22109163)。
文摘The detrimental“shuttle effect”of lithium polysulfides(LiPSs)together with sluggish multi-order reaction kinetics are the main drawbacks hindering lithium-sulfur(Li-S)batteries from commercial success.Here,we first propose the implementability of layered rare-earth hydroxides(LREHs)in Li-S batteries to optimize electrochemical performance.In this work,a two-dimensional(2D)rare-earth-based composite constructed by the layered gadolinium hydroxy chloride[Gd_(2)(OH)_(5)(H_(2)O)_(n)]Cl nanoplates(LGdH NPs)and graphene oxide(GO)was designed as a sulfur immobilizer for Li-S batteries.Combining the experimental results and density functional theory(DFT)calculations,it is revealed that the LGdH@GO composite not only provides a strong anchoring of the intermediates during cycling,but also acts as an effective catalyst to accelerate the liquid-solid conversion of polysulfides.The Li-S batteries assembled by LGdH@GO modified separators delivered a superior rate performance with a specific capacity of 605.34 mAh/g at 5 C,as well as excellent cycle stability with a decay rate of 0.087%over 500 cycles at 2 C.This study provided a deep understanding of the mechanism to suppress the“shuttle effect”by the LREHs,and a guide to design effective functional interlayers for high-performance Li-S batteries with excellent electrocatalytic activity.
基金Project supported by the National Natural Science Foundation of China(Grant No.10671156)the Natural Science Foundation of Shaanxi Province of China(Grant No.SJ08A05)
文摘By using the approximate derivative-dependent functional variable separation approach, we study the quasi-linear diffusion equations with a weak source ut = （A（u）Ux）x ＋ eB（u, Ux）. A complete classification of these perturbed equations which admit approximate derivative-dependent functional separable solutions is listed. As a consequence, some approxi- mate solutions to the resulting perturbed equations are constructed via examples.
