摘要
为了提高LiNi1/3Co1/3Mn1/3O2的电化学性能,采用非均匀成核法在球形LiNi1/3Co1/3Mn1/3O2表面包敷Al2O3。采用SEM及电化学性能测试对所制备材料的形貌和电化学性能进行表征。研究结果表明:球形LiNi1/3Co1/3Mn1/3O2颗粒由粒径为500～600 nm的一次粒子团聚而成,包敷后的球形LiNi1/3Co1/3Mn1/3O2表面形成了致密的无定形Al2O3包敷层;包覆Al2O3能明显抑制LiNi1/3Co1/3Mn1/3O2在循环过程中的氧化/还原峰电流的衰减,随着Al2O3包敷量的增加,材料的氧化/还原峰的峰电流减小,适量地包敷Al2O3可有效提高材料的可逆性;当Al2O3的包敷量为0.5%时,材料表现出优异的电化学性能,在2.7～4.6 V高电压和1C倍率条件下,材料的首次放电容量为172(mA.h)/g,50次循环后材料的容量保持率仍有93%,而没有包敷的LiNi1/3Co1/3Mn1/3O2容量略低,首次放电容量为170(mA.h)/g,而且容量衰减较快,容量保持率仅为84%。此外,包敷处理还可以有效提高LiNi1/3Co1/3Mn1/3O2材料在电解液中的热稳定性,以包敷材料所制备的电池其高温储存性能明显提高。
To improve the electrochemical performance of spherical LiNi1/3Co1/3Mn1/3O2 coated with Al2O3 using heterogeneous nucleation process,XRD and electrochemical tests were used to characterize the morphology and electrochemical properties.The results show that the particles are agglomerated with 500-600 nm grains and there is a uniform amorphous coat on the modified spherical LiNi1/3Co1/3Mn1/3O2.Al2O3-coating can evidently restrain the oxidation/reduction peaks currents fading during the charge/discharge process and proper coating can efficiently ameliorate the revisable ability.The properties of LiNi1/3Co1/3Mn1/3O2 coated with 0.5% Al2O3 show excellent electrochemical perofrmance.The initial capacity is 172（mA.h）/g at the rate of 1C and the voltage range of 2.7-4.6 V,the capacity retention ratio is 93% after 50 cycles.While the capacity attenuation of bare ones occurs much more quickly,and the capacity retention ratio is only 84% with 170（mA.h）/g.The surface coating can enhance its thermal stability in electrolyte and the storage performance of the cells at elevated temperature can be remarkably improved.
出处
《中南大学学报（自然科学版）》
EI
CAS
CSCD
北大核心
2010年第5期1703-1708,共6页
Journal of Central South University:Science and Technology
基金
国家重点基础研究计划("973"计划)项目(2007CB613607)
