Al-Ni掺杂改性LiMn2O4正极材料合成及电化学性能

Preparation and Electrochemical Performance of Al-Ni Doped Modified LiMn2O4 Cathode Material

摘要:

采用固相燃烧法快速合成了单晶多面体LiAl0.08Ni0.03Mn1.89O4 (LANMO)锂离子电池正极材料，其单晶颗粒暴露面包含{111}、{110}和{100}晶面。研究结果表明，LANMO材料为单相尖晶石型结构，属于Fd3m空间群，结晶性好，颗粒尺寸200-300 nm。在1 C和5 C倍率下LANMO的初始放电比容量分别为110.6和96 mAh·g-1，循环1000次后容量保持率都达到70%以上；在高温(55 ℃)1 C条件下，LANMO材料也具有114.2 mAh·g-1初始放电比容量，表现出优良的电化学性能。动力学性能测试表明，LANMO样品有较高的Li+离子扩散系数1.58×10-11 cm2·s-1和较低的表观活化能23.89 kJ?mol-1。Al-Ni协同改性提高了单晶多面体尖晶石型LiMn2O4材料的晶体结构稳定性，有效抑制了Jahn-Teller效应及降低Mn溶解和增加Li+扩散通道，增大了Li+扩散速率和电极可逆性，提升了其倍率性能和循环寿命。

Abstract:

The cathode material of single-crystal polyhedral LiAl0.08Ni0.03Mn1.89O4(LANMO) was rapidly synthesized by a solid-phase combustion method. The exposed surfaces of the single-crystal particles include {111}, {110} and {100} crystal faces. The results show that, LANMO material is a single-phase spinel structure, belonging to the space group Fd3m and exhibits a good crystallinity, the particle size is between 200 to 300 nm. The initial discharge specific capacity of LANMO is 110.6 and 96 mAh·g-1 at 1 C and 5 C, respectively, and the capacity retention rate reaches more than 70% after 1000 cycles. Under the elevated temperature (55 ℃) 1 C condition, the LANMO material also has an initial discharge specific capacity of 114.2 mAh·g-1, showing an excellent electrochemical performance. The kinetic performance test shows that the LANMO sample has a higher Li+ ion diffusion coefficient of 1.58×10-11 cm2 s-1 and a lower apparent activation energy of 23.89 kJ·mol-1. The Al-Ni synergistic modification improves the crystal structure stability of single crystal polyhedral spinel LiMn2O4 material, inhibits the Jahn-Teller effect effectively, reduces Mn dissolution, increases Li+ diffusion channels, Li+ diffusion rate and electrode reversibility as well as improves the rate performance and cycle life.