钙钛矿结构Li_(0.33)La_(0.557)Ti_(0.7)Cr_(0.3)O_(3)包覆稳定富锂锰基正极

Perovskite structure Li_(0.33)La_(0.557)Ti_(0.7)Cr_(0.3)O_(3)coated stable Li-rich Mnbased cathode

富锂锰基层状氧化物凭借超高的放电比容量和较低的价格成为了极具发展前景的锂离子电池正极材料,然而,首次库仑效率较低、容量衰减严重以及较差的倍率性能等缺点制约了其进一步的应用。选用离子-电子混合导体Li_(0.33)La_(0.557)Ti_(0.7)Cr_(0.3)O_(3)作为包覆层材料,并采用共沉淀法和高温退火法将其包覆于正极颗粒上。包覆量为2%的样品性能最佳,在0.5 C下、2.0~4.8 V电压范围内,200次循环容量保持率可以达到88.2%,相比于原始样品的62.1%有了明显的提升。

Lithium-rich manganese-based oxides have become a research hotspot due to their ultrahigh discharge specific capacity and low price,and they are promising cathode materials for lithium ion batteries.However,the disadvantages of low first coulombic efficiency,severe capacity fading,and poor rate performance restrict its further applications.In this paper,the ion-electron mixed conductor Li_(0.33)La_(0.557)Ti_(0.7)Cr_(0.3)O_(3)was selected as the coating material,and was coated on the positive electrode particles by co-precipitation and high temperature annealing.The sample with a coating amount of 2%has the best performance.At the current rate of 0.5 C and the voltage range of 2.0~4.8 V,the capacity retention rate after 200 cycles can reach 88.2%,which is a significant improvement compared with 62.1%of the pristine sample.