The Na-deficient P3-type layered oxide cathode material usually experience complex in-plane Na^(+)/vacancy ordering rearrangement and undesirable P3-O3 phase transitions in the high-voltage region,leading to inferior ...The Na-deficient P3-type layered oxide cathode material usually experience complex in-plane Na^(+)/vacancy ordering rearrangement and undesirable P3-O3 phase transitions in the high-voltage region,leading to inferior cycling performance.Additionally,they exhibit unsatisfactory stability when exposed to water for extended periods.To address these challenges,we propose a Cu/Ti co-doped P3-type cathode material(Na_(0.67)Ni_(0.3)Cu_(0.03)Mn_(0.6)Ti_(0.07)O_(2)),which effectively mitigates Na^(+)/vacancy ordering and suppresses P3-O3 phase transitions at high voltages.As a result,the as-prepared sample exhibited outstanding cyclic performance,with 81.9%retention after 500 cycles within 2.5–4.15 V,and 75.7%retention after300 cycles within 2.5–4.25 V.Meanwhile,it demonstrates enhanced Na^(+)transport kinetics during desodiation/sodiation and reduced growth of charge transfer impedance(R_(ct))after various cycles.Furthermore,the sample showed superb stability against water,exhibiting no discernible degradation in structure,morphology,or electrochemical performance.This co-doping strategy provides new insights for innovative and prospective cathode materials.展开更多
P2/O3-type Ni/Mn-based layered oxides are promising cathode materials for sodium-ion batteries(SIBs)owing to their high energy density.However,exploring effective ways to enhance the synergy between the P2 and 03 phas...P2/O3-type Ni/Mn-based layered oxides are promising cathode materials for sodium-ion batteries(SIBs)owing to their high energy density.However,exploring effective ways to enhance the synergy between the P2 and 03 phases remains a necessity.Herein,we design a P2/O3-type Na_(0.76)Ni_(0.31)Zn_(0.07)Mn_(0.50)Ti_(0.12)0_(2)(NNZMT)with high chemical/electrochemical stability by enhancing the coupling between the two phases.For the first time,a unique Na*extraction is observed from a Na-rich O3 phase by a Na-poor P2 phase and systematically investigated.This process is facilitated by Zn^(2+)/Ti^(4+)dual doping and calcination condition regulation,allowing a higher Na*content in the P2 phase with larger Na^(+)transport channels and enhancing Na transport kinetics.Because of reduced Na^(+)in the O3 phase,which increases the difficulty of H^(+)/Na^(+) exchange,the hydrostability of the O3 phase in NNZMT is considerably improved.Furthermore,Zn^(2+)/Ti^(4+)presence in NNZMT synergistically regulates oxygen redox chemistry,which effectively suppresses O_(2)/CO_(2) gas release and electrolyte decomposition,and completely inhibits phase transitions above 4.0 V.As a result,NNZMT achieves a high discharge capacity of 144.8 mA h g^(-1) with a median voltage of 3.42 V at 20 mA g^(-1) and exhibits excellent cycling performance with a capacity retention of 77.3% for 1000 cycles at 2000 mA g^(-1).This study provides an effective strategy and new insights into the design of high-performance layered-oxide cathode materials with enhanced structure/interface stability forSIBs.展开更多
The effect of Na-excess content in the precursor on the structural and electrochemical performances of sodium nickel manganese oxide(NNMO)prepared by sol-gel and electrospinning methods is investigated in this paper.X...The effect of Na-excess content in the precursor on the structural and electrochemical performances of sodium nickel manganese oxide(NNMO)prepared by sol-gel and electrospinning methods is investigated in this paper.X-ray diffraction results of the prepared NNMO without adding Na-excess content indicate sodium loss,while the mixed phase of P2/O′3-type layered NNMO presented after adding Na-excess content.Compared with the sol-gel method,the secondary phase of NiO is more suppressed by using the electrospinning method,which is further confirmed by field emission scanning electron microscope images.N_(2) adsorption-desorption isotherms show no remarkably difference in specific surface areas between different preparation methods and Na-excess contents.The analysis of X-ray absorption near edge structure indicates that the oxidation states of Ni and Mn are+2 and+4,respectively.For the electrochemical properties,superior electrochemical performance is observed in the NNMO electrode with a low Na-excess content of 5wt%.The highest specific capacitance is 36.07 F·g^(-1)at0.1 A·g^(-1)in the NNMO electrode prepared by using the sol-gel method.By contrast,the NNMO electrode prepared using the electrospinning method with decreased Na-excess content shows excellent cycling stability of 100%after charge-discharge measurements for 300 cycles.Therefore,controlling the Na excess in the precursor together with the preparation method is important for improving the electrochemical performance of Na-based electrode materials in supercapacitors.展开更多
Potassium-ions batteries(PIBs)are attracting increasing attention as up-and-coming youngster in largescale grid-level energy storage benefiting from its low-cost and high energy density.Nevertheless,enough researches ...Potassium-ions batteries(PIBs)are attracting increasing attention as up-and-coming youngster in largescale grid-level energy storage benefiting from its low-cost and high energy density.Nevertheless,enough researches regarding indispensable cathode materials for PIBs are badly absent.Herein,we synthesize K-deficient layered manganese-based oxides(P2-K_(0.21)MnO_(2) and P3-K_(0.23)MnO_(2))and investigate them as cathode of PIBs for the first time.As the newcomer of potassium-containing layered manganese-based oxides(K_(x)MnO_(2))group,P2-K_(0.21)MnO_(2) delivers high discharge capacity of 99.3 mAh g^(-1) and P3-K_(0.23)MnO_(2) exhibits remarkable capacity retention rate of 75.5%.Besides,in-situ XRD and ex-situ XRD measurements reveal the reversible phase transition of P2-K_(0.21)MnO_(2) and P3-K_(0.23)MnO_(2) with the potassium-ions extraction and reinsertion,respectively.This work contributes to a better understanding for the potassium storage in K-deficient layered K_(x)MnO_(2)(x≤0.23),possessing an important basic scientific significance for the exploitation and application of layered K_(x)MnO_(2) in PIBs.展开更多
基金supported by the National Natural Science Foundation of China(Nos.22179077,51774251,21908142)Shanghai Science and Technology Commission’s“2020 Science and Technology In-novation Action Plan”(No.20511104003)Natural Science Foundation in Shanghai(No.21ZR1424200)。
文摘The Na-deficient P3-type layered oxide cathode material usually experience complex in-plane Na^(+)/vacancy ordering rearrangement and undesirable P3-O3 phase transitions in the high-voltage region,leading to inferior cycling performance.Additionally,they exhibit unsatisfactory stability when exposed to water for extended periods.To address these challenges,we propose a Cu/Ti co-doped P3-type cathode material(Na_(0.67)Ni_(0.3)Cu_(0.03)Mn_(0.6)Ti_(0.07)O_(2)),which effectively mitigates Na^(+)/vacancy ordering and suppresses P3-O3 phase transitions at high voltages.As a result,the as-prepared sample exhibited outstanding cyclic performance,with 81.9%retention after 500 cycles within 2.5–4.15 V,and 75.7%retention after300 cycles within 2.5–4.25 V.Meanwhile,it demonstrates enhanced Na^(+)transport kinetics during desodiation/sodiation and reduced growth of charge transfer impedance(R_(ct))after various cycles.Furthermore,the sample showed superb stability against water,exhibiting no discernible degradation in structure,morphology,or electrochemical performance.This co-doping strategy provides new insights for innovative and prospective cathode materials.
基金supported by the National Natural Science Foundation of China (22169002)the Chongzuo Key Research and Development Program of China (20220603)the Counterpart Aid Project for Discipline Construction from Guangxi University(2023M02)
文摘P2/O3-type Ni/Mn-based layered oxides are promising cathode materials for sodium-ion batteries(SIBs)owing to their high energy density.However,exploring effective ways to enhance the synergy between the P2 and 03 phases remains a necessity.Herein,we design a P2/O3-type Na_(0.76)Ni_(0.31)Zn_(0.07)Mn_(0.50)Ti_(0.12)0_(2)(NNZMT)with high chemical/electrochemical stability by enhancing the coupling between the two phases.For the first time,a unique Na*extraction is observed from a Na-rich O3 phase by a Na-poor P2 phase and systematically investigated.This process is facilitated by Zn^(2+)/Ti^(4+)dual doping and calcination condition regulation,allowing a higher Na*content in the P2 phase with larger Na^(+)transport channels and enhancing Na transport kinetics.Because of reduced Na^(+)in the O3 phase,which increases the difficulty of H^(+)/Na^(+) exchange,the hydrostability of the O3 phase in NNZMT is considerably improved.Furthermore,Zn^(2+)/Ti^(4+)presence in NNZMT synergistically regulates oxygen redox chemistry,which effectively suppresses O_(2)/CO_(2) gas release and electrolyte decomposition,and completely inhibits phase transitions above 4.0 V.As a result,NNZMT achieves a high discharge capacity of 144.8 mA h g^(-1) with a median voltage of 3.42 V at 20 mA g^(-1) and exhibits excellent cycling performance with a capacity retention of 77.3% for 1000 cycles at 2000 mA g^(-1).This study provides an effective strategy and new insights into the design of high-performance layered-oxide cathode materials with enhanced structure/interface stability forSIBs.
基金financially supported by (i) Suranaree University of Technology,(ii) Thailand Science Research and Innovation,and (iii) National Science,Research and Innovation Fund(project codes 90464 and 160363)。
文摘The effect of Na-excess content in the precursor on the structural and electrochemical performances of sodium nickel manganese oxide(NNMO)prepared by sol-gel and electrospinning methods is investigated in this paper.X-ray diffraction results of the prepared NNMO without adding Na-excess content indicate sodium loss,while the mixed phase of P2/O′3-type layered NNMO presented after adding Na-excess content.Compared with the sol-gel method,the secondary phase of NiO is more suppressed by using the electrospinning method,which is further confirmed by field emission scanning electron microscope images.N_(2) adsorption-desorption isotherms show no remarkably difference in specific surface areas between different preparation methods and Na-excess contents.The analysis of X-ray absorption near edge structure indicates that the oxidation states of Ni and Mn are+2 and+4,respectively.For the electrochemical properties,superior electrochemical performance is observed in the NNMO electrode with a low Na-excess content of 5wt%.The highest specific capacitance is 36.07 F·g^(-1)at0.1 A·g^(-1)in the NNMO electrode prepared by using the sol-gel method.By contrast,the NNMO electrode prepared using the electrospinning method with decreased Na-excess content shows excellent cycling stability of 100%after charge-discharge measurements for 300 cycles.Therefore,controlling the Na excess in the precursor together with the preparation method is important for improving the electrochemical performance of Na-based electrode materials in supercapacitors.
基金support from the Key Project of Guangdong Province Nature Science Foundation (No. 2017B030311013)the Scientific and Technological Plan of Guangdong Province, Guangzhou and Qingyuan City, China (Nos. 2019B090905005, 2019B090911004, 2017B020227009, 2019DZX008, 2019A004)+2 种基金the financial support from the National Key R&D Program of China (2018YFB1502600)the National Natural Science Foundation of China (No. 51922042 and 51872098)the Sino-Singapore International Joint Research Institute (SSIJRI), Guangzhou 510700, China.
文摘Potassium-ions batteries(PIBs)are attracting increasing attention as up-and-coming youngster in largescale grid-level energy storage benefiting from its low-cost and high energy density.Nevertheless,enough researches regarding indispensable cathode materials for PIBs are badly absent.Herein,we synthesize K-deficient layered manganese-based oxides(P2-K_(0.21)MnO_(2) and P3-K_(0.23)MnO_(2))and investigate them as cathode of PIBs for the first time.As the newcomer of potassium-containing layered manganese-based oxides(K_(x)MnO_(2))group,P2-K_(0.21)MnO_(2) delivers high discharge capacity of 99.3 mAh g^(-1) and P3-K_(0.23)MnO_(2) exhibits remarkable capacity retention rate of 75.5%.Besides,in-situ XRD and ex-situ XRD measurements reveal the reversible phase transition of P2-K_(0.21)MnO_(2) and P3-K_(0.23)MnO_(2) with the potassium-ions extraction and reinsertion,respectively.This work contributes to a better understanding for the potassium storage in K-deficient layered K_(x)MnO_(2)(x≤0.23),possessing an important basic scientific significance for the exploitation and application of layered K_(x)MnO_(2) in PIBs.
