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
The spinel lithium manganese oxide cathode materials were prepared by adipic acid-assisted sol-gel method at 350～900 ℃ in air. The effects of water content of solution, molar ratio between metal ion and adipic acid,...The spinel lithium manganese oxide cathode materials were prepared by adipic acid-assisted sol-gel method at 350～900 ℃ in air. The effects of water content of solution, molar ratio between metal ion and adipic acid, cooling rate, synthesis temperature and particle sizes on structure and electrochemical performance of LiMn_2O_4 are investigated by X-ray diffraction (XRD), and cyclic voltammetry (CV). The result shows that the structure and electrochemical performance of LiMn_2O_4 are greatly affected by synthesis condition, and the optimal synthesis condition is determined. Charge-discharge test reveals that the particle size and cooling rate have significant effects on the electrochemical performance of LiMn_2O_4 cathode materials.展开更多
A normal spinel LiMn_2O_4 as cathode material for lithium-ion cells wascycled galvanostatically (0.2 C) at 55 deg C. To determine the contribution of each voltage plateauto the total capacity fading of the cathode upo...A normal spinel LiMn_2O_4 as cathode material for lithium-ion cells wascycled galvanostatically (0.2 C) at 55 deg C. To determine the contribution of each voltage plateauto the total capacity fading of the cathode upon repeated cycling, the capacities in each plateauwere separated by differentiation of voltage vs. capacity. The results how that the capacity fadingin the upper voltage plateau is more rapidly than that in the lower during discharging, while incharging process, it fades slower than that in the lower voltage range. The increased capacity shiftand aggravated self-discharge/electrolyte oxidation during discharging contribute to a high fadingrate in the upper step. Capacity shift also takes place during charging process, which againenhancing the fading rate of the lower voltage plateau. An increase in capacity shift, as a resultof an increase in polarization of the cell, plays a major role in determining the fading rate ineach voltage plateau, further reflecting the thickening of the passivation layer on the activeparticles, and the accumulation of electrolyte decomposition. The relative capacity loss formodified spinels is well correlated with the relative increase in the polarization of thehalf-cells, confirming the above causes for capacity fade of this kind of cathode material.展开更多
We present an efficient strategy,that is the co-substitution of Fe^(3+)and Ta^(5+)ions with large radius for Ti^(4+)ion,to enhance energy storage performance of Ba_(2)Bi_(4)Ti_(5)O_(18) film.For the films co-doped wit...We present an efficient strategy,that is the co-substitution of Fe^(3+)and Ta^(5+)ions with large radius for Ti^(4+)ion,to enhance energy storage performance of Ba_(2)Bi_(4)Ti_(5)O_(18) film.For the films co-doped with Fe^(3+)and Ta^(5+)ions,the maximum polarization under the same external electric field is improved because the radius of Fe^(3+)and Ta^(5+)ions is larger than that of Ti^(4+)ion.Moreover,due to the composition and chemical disorder,the relaxor properties are also slightly improved,which can not be achieved by the film doped with Fe^(3+)ions only.What is more,for the films doped with Fe^(3+)ion only,the leakage current density increases greatly due to the charge imbalance,resulting in a significant decrease in breakdown strength.It is worth mentioning that the breakdown strength of Fe^(3+)and Ta^(5+)ions co-doped film does not decrease due to the charge balance.Another important point is the recoverable energy storage density of the films co-doped with Fe^(3+)and Ta^(5+)ions has been greatly improved based on the fact that the maximum external electric field does not decrease and the maximum polarization under the same external electric field increases.On top of that,the hysteresis of the polarization has also been improved.Finally,the co-doped films with Fe^(3+)and Ta^(5+)ions have good frequency and temperature stability.展开更多
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.
文摘The spinel lithium manganese oxide cathode materials were prepared by adipic acid-assisted sol-gel method at 350～900 ℃ in air. The effects of water content of solution, molar ratio between metal ion and adipic acid, cooling rate, synthesis temperature and particle sizes on structure and electrochemical performance of LiMn_2O_4 are investigated by X-ray diffraction (XRD), and cyclic voltammetry (CV). The result shows that the structure and electrochemical performance of LiMn_2O_4 are greatly affected by synthesis condition, and the optimal synthesis condition is determined. Charge-discharge test reveals that the particle size and cooling rate have significant effects on the electrochemical performance of LiMn_2O_4 cathode materials.
文摘A normal spinel LiMn_2O_4 as cathode material for lithium-ion cells wascycled galvanostatically (0.2 C) at 55 deg C. To determine the contribution of each voltage plateauto the total capacity fading of the cathode upon repeated cycling, the capacities in each plateauwere separated by differentiation of voltage vs. capacity. The results how that the capacity fadingin the upper voltage plateau is more rapidly than that in the lower during discharging, while incharging process, it fades slower than that in the lower voltage range. The increased capacity shiftand aggravated self-discharge/electrolyte oxidation during discharging contribute to a high fadingrate in the upper step. Capacity shift also takes place during charging process, which againenhancing the fading rate of the lower voltage plateau. An increase in capacity shift, as a resultof an increase in polarization of the cell, plays a major role in determining the fading rate ineach voltage plateau, further reflecting the thickening of the passivation layer on the activeparticles, and the accumulation of electrolyte decomposition. The relative capacity loss formodified spinels is well correlated with the relative increase in the polarization of thehalf-cells, confirming the above causes for capacity fade of this kind of cathode material.
基金This work was financially supported by the National Natural Science Foundation of China(Grant Nos.12074204,11864028,and 11904054)the Natural Science Foundation of Inner Mongolia,China(Grant No.2022ZD06).
文摘We present an efficient strategy,that is the co-substitution of Fe^(3+)and Ta^(5+)ions with large radius for Ti^(4+)ion,to enhance energy storage performance of Ba_(2)Bi_(4)Ti_(5)O_(18) film.For the films co-doped with Fe^(3+)and Ta^(5+)ions,the maximum polarization under the same external electric field is improved because the radius of Fe^(3+)and Ta^(5+)ions is larger than that of Ti^(4+)ion.Moreover,due to the composition and chemical disorder,the relaxor properties are also slightly improved,which can not be achieved by the film doped with Fe^(3+)ions only.What is more,for the films doped with Fe^(3+)ion only,the leakage current density increases greatly due to the charge imbalance,resulting in a significant decrease in breakdown strength.It is worth mentioning that the breakdown strength of Fe^(3+)and Ta^(5+)ions co-doped film does not decrease due to the charge balance.Another important point is the recoverable energy storage density of the films co-doped with Fe^(3+)and Ta^(5+)ions has been greatly improved based on the fact that the maximum external electric field does not decrease and the maximum polarization under the same external electric field increases.On top of that,the hysteresis of the polarization has also been improved.Finally,the co-doped films with Fe^(3+)and Ta^(5+)ions have good frequency and temperature stability.
