High-capacity nickel-rich layered oxides are promising cathode materials for high-energy-density lithium batteries.However,the poor structural stability and severe side reactions at the electrode/electrolyte interface...High-capacity nickel-rich layered oxides are promising cathode materials for high-energy-density lithium batteries.However,the poor structural stability and severe side reactions at the electrode/electrolyte interface result in unsatisfactory cycle performance.Herein,the thin layer of two-dimensional(2D)graphitic carbon-nitride(g-C_(3)N_(4))is uniformly coated on the LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)(denoted as NCM811@CN)using a facile chemical vaporization-assisted synthesis method.As an ideal protective layer,the g-C_(3)N_(4)layer effectively avoids direct contact between the NCM811 cathode and the electrolyte,preventing harmful side reactions and inhibiting secondary crystal cracking.Moreover,the unique nanopore structure and abundant nitrogen vacancy edges in g-C_(3)N_(4)facilitate the adsorption and diffusion of lithium ions,which enhances the lithium deintercalation/intercalation kinetics of the NCM811 cathode.As a result,the NCM811@CN-3wt%cathode exhibits 161.3 mAh g^(−1)and capacity retention of 84.6%at 0.5 C and 55°C after 400 cycles and 95.7 mAh g^(−1)at 10 C,which is greatly superior to the uncoated NCM811(i.e.129.3 mAh g^(−1)and capacity retention of 67.4%at 0.5 C and 55°C after 220 cycles and 28.8 mAh g^(−1)at 10 C).The improved cycle performance of the NCM811@CN-3wt%cathode is also applicable to solid–liquid-hybrid cells composed of PVDF:LLZTO electrolyte membranes,which show 163.8 mAh g^(−1)and the capacity retention of 88.1%at 0.1 C and 30°C after 200 cycles and 95.3 mAh g^(−1)at 1 C.展开更多
The present commercial spinel LiMn_(2)O_(4) delivers only 90 m Ah/g–115 m Ah/g,far lower than the theoretical specific capacity.It degrades fast caused by the Jahn–Teller effect,Mn dissolution and related side react...The present commercial spinel LiMn_(2)O_(4) delivers only 90 m Ah/g–115 m Ah/g,far lower than the theoretical specific capacity.It degrades fast caused by the Jahn–Teller effect,Mn dissolution and related side reactions that consume Li inventory.In this work,Zr doping is employed to improve the structural stability and electrochemical performance of spinel LiMn_(2)O_(4).Li_(1.06)Mn_(1.94-x)Zr_xO_4(x=0,0.01,0.02,0.04)have been successfully synthesized by a simple solid-state reaction method and evaluated as cathode for lithium ion batteries(LIB).Li_(1.06)Mn_(1.92)Zr_(0.02)O_4 is superior cathode material with a high capacity of 122 m Ah/g at 1-C rate;long cycle stability,98.39%retention after 100 cycles at 1-C rate,excellent high rate performance 107.1 m Ah/g at 10-C rate,and high temperature performance 97.39%retention after 60 cycles.These are thought to be related to Zr doping effectively stabilizing the spinel LiMn_(2)O_(4),by forming stronger Zr–O bonds in the octahedron,suppressing the Jahn–Teller effect,thus improving electrochemical performance.展开更多
通过溶胶凝胶法制备出LiMn_2O_4和LiMn_(1.92)Mg_(0.08)O_(3.84)Br_(0.16)锂离子电池正极材料,并用XRD、SEM、XPS、充放电测试和CV对其结构、形貌、化学成份以及电化学性能进行了研究。结果表明,Mg、Br的掺杂未改变LiMn_2O_4的结构。在0...通过溶胶凝胶法制备出LiMn_2O_4和LiMn_(1.92)Mg_(0.08)O_(3.84)Br_(0.16)锂离子电池正极材料,并用XRD、SEM、XPS、充放电测试和CV对其结构、形貌、化学成份以及电化学性能进行了研究。结果表明,Mg、Br的掺杂未改变LiMn_2O_4的结构。在0.5 C倍率下,LiMn_(1.92)Mg_(0.08)O_(3.84)Br_(0.16)的放电比容量为119 m Ah/g,与LiMn_2O_4相比,其首次放电比容量提高了3.6%,循环100次后,Li Mn1.92Mg0.08O3.84Br0.16的容量保持率高达86.9%。在5 C倍率下,LiMn_(1.92)Mg_(0.08)O_(3.84)Br_(0.16)的放电比容量为91.1 m Ah/g,比LiMn_2O_4提高了24.1%。实验表明,Mg、Br共同掺杂提高了LiMn_2O_4的放电比容量,并明显改善其循环稳定性和倍率性能,从而获得了较好的综合电化学性能。展开更多
为进一步提高动力电池正极材料锰酸锂(LiMn_2O_4)的循环稳定性,通过溶胶-凝胶法用快离子导体La_(0.8)Sr_(0.2)MnO_3作为包覆材料对LiMn_2O_4进行表面修饰,探讨了不同包覆量对复合材料电化学性能的影响。采用X射线衍射仪(XRD)、场发射扫...为进一步提高动力电池正极材料锰酸锂(LiMn_2O_4)的循环稳定性,通过溶胶-凝胶法用快离子导体La_(0.8)Sr_(0.2)MnO_3作为包覆材料对LiMn_2O_4进行表面修饰,探讨了不同包覆量对复合材料电化学性能的影响。采用X射线衍射仪(XRD)、场发射扫描电镜(FESEM)和透射电子显微镜(TEM)对样品的微观结构以及形貌进行表征。结果表明:La_(0.8)Sr_(0.2)MnO_3的包覆并没有改变LiMn_2O_4晶体结构及空间构型;相比纯的LiMn_2O_4样品,La_(0.8)Sr_(0.2)MnO_3包覆后的样品颗粒表面较为粗糙;涂层为薄膜状结构,均匀且完全包覆在LiMn_2O_4颗粒的表面。利用电化学测试方法测试其电化学性能,测试结果表明,当La_(0.8)Sr_(0.2)MnO_3包覆量为5%时,具有较好的电化学性能,首次放电比容量为127.4 m A·h/g(0.1 C),25℃循环400次后容量保持率为91.2%,55℃循环100次后容量保持率为91.1%;与未经表面修饰的样品相比,其首次放电比容量为119.1 m A·h/g(0.1 C),400次的容量保持率为61.9%,100次容量保持率为77.9%,La_(0.8)Sr_(0.2)MnO_3包覆后的样品的电化学性能尤其是循环性能得到明显的提高。展开更多
LiMn_(2)O_(4)(LMO)electrochemical lithium-ion pump has gained widespread attention due to its green,high efficiency,and low energy consumption in selectively extracting lithium from brine.However,collapse of crystal s...LiMn_(2)O_(4)(LMO)electrochemical lithium-ion pump has gained widespread attention due to its green,high efficiency,and low energy consumption in selectively extracting lithium from brine.However,collapse of crystal structure and loss of lithium extraction capacity caused by Mn dissolution loss limits its industrialized application.Hence,a multifunctional coating was developed by depositing amorphous AlPO_(4)on the surface of LMO using sol-gel method.The characterization and electrochemical performance test provided insights into the mechanism of Li^(+)embedment and de-embedment and revealed that multifunctional AlPO_(4)can reconstruct the physical and chemical state of LMO surface to improve the interface hydrophilicity,promote the transport of Li^(+),strengthen cycle stability.Remarkably,after 20 cycles,the capacity retention rate of 0.5AP-LMO reached 93.6%with only 0.147%Mn dissolution loss.The average Li^(+)release capacity of 0.5AP-LMO//Ag system in simulated brine is 28.77 mg/(g h),which is 90.4%higher than LMO.Encouragingly,even in the more complex Zabuye real brine,0.5AP-LMO//Ag can still maintain excellent lithium extraction performance.These results indicate that the 0.5AP-LMO//Ag lithium-ion pump shows promising potential as a Li^(+)selective extraction system.展开更多
Ethylene carbonate(EC)is widely used in lithium-ion batteries due to its optimal overall performance with satisfactory conductivity,relatively stable solid electrolyte interphase(SEI),and wide electrochemical window.E...Ethylene carbonate(EC)is widely used in lithium-ion batteries due to its optimal overall performance with satisfactory conductivity,relatively stable solid electrolyte interphase(SEI),and wide electrochemical window.EC is also the most widely used electrolyte solvent in sodium ion batteries.However,compared to lithium metal,sodium metal(Na)shows higher activity and reacts violently with EC-based electrolyte(NaPF_(6)as solute),which leads to the failure of sodium metal batteries(SMBs).Herein,we reveal the electrochemical instability mechanism of EC on sodium metal battery,and find that the com-bination of EC and NaPF_(6) is electrically reduced in sodium metal anode during charging,resulting in the reduction of the first coulombic efficiency,and the continuous consumption of electrolyte leads to the cell failure.To address the above issues,an additive modified linear carbonate-based electrolyte is provided as a substitute for EC based electrolytes.Specifically,ethyl methyl carbonate(EMC)and dimethyl carbon-ate(DMC)as solvents and fluoroethylene carbonate(FEC)as SEI-forming additive have been identified as the optimal solvent for NaFP_(6)based electrolyte and used in Na_(4)Fe_(3)(PO_(4))_(2)(P_(2)O_(7))/Na batteries.The batter-ies exhibit excellent capacity retention rate of about 80%over 1000 cycles at a cut-off voltage of 4.3 V.展开更多
基金supported by the National Key R&D Program of China(Grant No.2023YFB2503900)the National Natural Science Foundation of China(Grant No.52372203)+1 种基金the National Natural Science Foundation of China(Grant No.52202259)the Shandong Province Natural Science Foundation(ZR2022QE093).
文摘High-capacity nickel-rich layered oxides are promising cathode materials for high-energy-density lithium batteries.However,the poor structural stability and severe side reactions at the electrode/electrolyte interface result in unsatisfactory cycle performance.Herein,the thin layer of two-dimensional(2D)graphitic carbon-nitride(g-C_(3)N_(4))is uniformly coated on the LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)(denoted as NCM811@CN)using a facile chemical vaporization-assisted synthesis method.As an ideal protective layer,the g-C_(3)N_(4)layer effectively avoids direct contact between the NCM811 cathode and the electrolyte,preventing harmful side reactions and inhibiting secondary crystal cracking.Moreover,the unique nanopore structure and abundant nitrogen vacancy edges in g-C_(3)N_(4)facilitate the adsorption and diffusion of lithium ions,which enhances the lithium deintercalation/intercalation kinetics of the NCM811 cathode.As a result,the NCM811@CN-3wt%cathode exhibits 161.3 mAh g^(−1)and capacity retention of 84.6%at 0.5 C and 55°C after 400 cycles and 95.7 mAh g^(−1)at 10 C,which is greatly superior to the uncoated NCM811(i.e.129.3 mAh g^(−1)and capacity retention of 67.4%at 0.5 C and 55°C after 220 cycles and 28.8 mAh g^(−1)at 10 C).The improved cycle performance of the NCM811@CN-3wt%cathode is also applicable to solid–liquid-hybrid cells composed of PVDF:LLZTO electrolyte membranes,which show 163.8 mAh g^(−1)and the capacity retention of 88.1%at 0.1 C and 30°C after 200 cycles and 95.3 mAh g^(−1)at 1 C.
基金research on high power flexible battery in all sea depth(Grant No.2020-XXXX-XX-246-00)。
文摘The present commercial spinel LiMn_(2)O_(4) delivers only 90 m Ah/g–115 m Ah/g,far lower than the theoretical specific capacity.It degrades fast caused by the Jahn–Teller effect,Mn dissolution and related side reactions that consume Li inventory.In this work,Zr doping is employed to improve the structural stability and electrochemical performance of spinel LiMn_(2)O_(4).Li_(1.06)Mn_(1.94-x)Zr_xO_4(x=0,0.01,0.02,0.04)have been successfully synthesized by a simple solid-state reaction method and evaluated as cathode for lithium ion batteries(LIB).Li_(1.06)Mn_(1.92)Zr_(0.02)O_4 is superior cathode material with a high capacity of 122 m Ah/g at 1-C rate;long cycle stability,98.39%retention after 100 cycles at 1-C rate,excellent high rate performance 107.1 m Ah/g at 10-C rate,and high temperature performance 97.39%retention after 60 cycles.These are thought to be related to Zr doping effectively stabilizing the spinel LiMn_(2)O_(4),by forming stronger Zr–O bonds in the octahedron,suppressing the Jahn–Teller effect,thus improving electrochemical performance.
文摘通过溶胶凝胶法制备出LiMn_2O_4和LiMn_(1.92)Mg_(0.08)O_(3.84)Br_(0.16)锂离子电池正极材料,并用XRD、SEM、XPS、充放电测试和CV对其结构、形貌、化学成份以及电化学性能进行了研究。结果表明,Mg、Br的掺杂未改变LiMn_2O_4的结构。在0.5 C倍率下,LiMn_(1.92)Mg_(0.08)O_(3.84)Br_(0.16)的放电比容量为119 m Ah/g,与LiMn_2O_4相比,其首次放电比容量提高了3.6%,循环100次后,Li Mn1.92Mg0.08O3.84Br0.16的容量保持率高达86.9%。在5 C倍率下,LiMn_(1.92)Mg_(0.08)O_(3.84)Br_(0.16)的放电比容量为91.1 m Ah/g,比LiMn_2O_4提高了24.1%。实验表明,Mg、Br共同掺杂提高了LiMn_2O_4的放电比容量,并明显改善其循环稳定性和倍率性能,从而获得了较好的综合电化学性能。
文摘为进一步提高动力电池正极材料锰酸锂(LiMn_2O_4)的循环稳定性,通过溶胶-凝胶法用快离子导体La_(0.8)Sr_(0.2)MnO_3作为包覆材料对LiMn_2O_4进行表面修饰,探讨了不同包覆量对复合材料电化学性能的影响。采用X射线衍射仪(XRD)、场发射扫描电镜(FESEM)和透射电子显微镜(TEM)对样品的微观结构以及形貌进行表征。结果表明:La_(0.8)Sr_(0.2)MnO_3的包覆并没有改变LiMn_2O_4晶体结构及空间构型;相比纯的LiMn_2O_4样品,La_(0.8)Sr_(0.2)MnO_3包覆后的样品颗粒表面较为粗糙;涂层为薄膜状结构,均匀且完全包覆在LiMn_2O_4颗粒的表面。利用电化学测试方法测试其电化学性能,测试结果表明,当La_(0.8)Sr_(0.2)MnO_3包覆量为5%时,具有较好的电化学性能,首次放电比容量为127.4 m A·h/g(0.1 C),25℃循环400次后容量保持率为91.2%,55℃循环100次后容量保持率为91.1%;与未经表面修饰的样品相比,其首次放电比容量为119.1 m A·h/g(0.1 C),400次的容量保持率为61.9%,100次容量保持率为77.9%,La_(0.8)Sr_(0.2)MnO_3包覆后的样品的电化学性能尤其是循环性能得到明显的提高。
基金supported by the National Natural Science Foundation of China(21908082,22278426,and 22178154)the Jiangsu Funding Program for Excellent Postdoctoral Talent(2022ZB629)+1 种基金the Natural Science Foundation of Jiangsu Province(BK20221367)the China Postdoctoral Science Foundation(2021M701472)。
文摘LiMn_(2)O_(4)(LMO)electrochemical lithium-ion pump has gained widespread attention due to its green,high efficiency,and low energy consumption in selectively extracting lithium from brine.However,collapse of crystal structure and loss of lithium extraction capacity caused by Mn dissolution loss limits its industrialized application.Hence,a multifunctional coating was developed by depositing amorphous AlPO_(4)on the surface of LMO using sol-gel method.The characterization and electrochemical performance test provided insights into the mechanism of Li^(+)embedment and de-embedment and revealed that multifunctional AlPO_(4)can reconstruct the physical and chemical state of LMO surface to improve the interface hydrophilicity,promote the transport of Li^(+),strengthen cycle stability.Remarkably,after 20 cycles,the capacity retention rate of 0.5AP-LMO reached 93.6%with only 0.147%Mn dissolution loss.The average Li^(+)release capacity of 0.5AP-LMO//Ag system in simulated brine is 28.77 mg/(g h),which is 90.4%higher than LMO.Encouragingly,even in the more complex Zabuye real brine,0.5AP-LMO//Ag can still maintain excellent lithium extraction performance.These results indicate that the 0.5AP-LMO//Ag lithium-ion pump shows promising potential as a Li^(+)selective extraction system.
基金supported by the National Natural Science Foundation of China(52172201,51732005,51902118,and 52102249)the China Postdoctoral Science Foundation(2019M662609and 2020T130217)for financial support。
文摘Ethylene carbonate(EC)is widely used in lithium-ion batteries due to its optimal overall performance with satisfactory conductivity,relatively stable solid electrolyte interphase(SEI),and wide electrochemical window.EC is also the most widely used electrolyte solvent in sodium ion batteries.However,compared to lithium metal,sodium metal(Na)shows higher activity and reacts violently with EC-based electrolyte(NaPF_(6)as solute),which leads to the failure of sodium metal batteries(SMBs).Herein,we reveal the electrochemical instability mechanism of EC on sodium metal battery,and find that the com-bination of EC and NaPF_(6) is electrically reduced in sodium metal anode during charging,resulting in the reduction of the first coulombic efficiency,and the continuous consumption of electrolyte leads to the cell failure.To address the above issues,an additive modified linear carbonate-based electrolyte is provided as a substitute for EC based electrolytes.Specifically,ethyl methyl carbonate(EMC)and dimethyl carbon-ate(DMC)as solvents and fluoroethylene carbonate(FEC)as SEI-forming additive have been identified as the optimal solvent for NaFP_(6)based electrolyte and used in Na_(4)Fe_(3)(PO_(4))_(2)(P_(2)O_(7))/Na batteries.The batter-ies exhibit excellent capacity retention rate of about 80%over 1000 cycles at a cut-off voltage of 4.3 V.
