界面三维扩散通道与富锂锰基的协同效应研究

Design of three-dimensional diffusion channels at the interface to improve the dynamic performance of lithium rich manganese based cathode

富锂锰基正极材料具有诸多优点,但是其低锂离子电导率和高扩散势垒严重影响其倍率性能。提出了快离子导体磷酸钛铝锂表面包覆改性策略,分析了富锂锰基正极材料与磷酸钛铝锂包覆层的协同效应。结果表明:在700℃煅烧5 h,包覆量为3%(质量分数)Li_(1.3)Ti_(1.7)Al_(0.3)(PO_(4))_(3)的Li-[Li_(0.2)Mn_(0.54)Ni_(0.13)Co_(0.13)]O_(2)具有最佳的性能,在100次循环后,放电比容量为226.5 mAh/g,保持率为89.7%。其优异的电化学性能可归因于包覆层提供三维锂离子扩散通道,减小了电极-电解液界面迁移阻抗。

Rich lithium manganese based cathode materials have many advantages,but their low lithium ion conductivity and high diffusion barrier seriously affect their rate performance.In addition,during the cycle process,a large amount of loss of active substances can lead to severe degradation of cycle performance.Based on the above issues,this paper proposes a surface coating modification strategy for fast ion conductor titanium aluminum lithium phosphate,and analyzes the synergistic effect between lithium rich manganese based cathode materials and titanium aluminum lithium phosphate coating.The results show that the coating layer provides a three-dimensional lithium ion diffusion channel,reduces the electrode electrolyte interface migration impedance.At the same time,it inhibits the occurrence of side reactions and protects the surface structure of the material.The effect of different coating amounts on the multiphase material was studied.After calcining at 700℃for 5 hours,Li[Li_(0.2)Mn_(0.54)Ni_(0.13)Co_(0.13)]O_(2)with a coating amount of 3%LiLi_(1.3)Ti_(1.7)Al_(0.3)(PO_(4))_(3) had the best performance.After 100 cycles,226.5 mAh/g and a retention rate of 89.7%were obtained.