采用固相燃烧法快速合成了LiNi_0.08Fe_xMn_1.92-xO₄(x≤0.08)正极材料,并探究了正极材料样品的结构、形貌、电化学性能及动力学性能。结果表明,Ni-Fe共掺没有改变LiMn₂O₄的立方尖晶石结构,促进了其晶体发育和{111}、{110}、{100}晶面的择优生长,部分颗粒形成了以高暴露{111}晶面为主和少量{110}、{100}晶面的截断八面体形貌。LiNi_0.08Fe_0.05Mn_1.87O₄样品在较低倍率(≤5 C)时,其倍率性能和长循环寿命得到显著提高,在25℃下,1 C的首次放电比容量为106.1 mAh/g,1 000次循环后容量保持率为82.0%;5 C的首次放电比容量为100.1 mAh/g,2 000次循环后容量保持率为72.8%。LiNi_0.08Fe_0.05Mn_1.87O₄材料的锂离子扩散系数和表观活化能分别为1.75×10^-15 cm²/s和26.52 kJ/mol,表明其有较好的Li⁺迁移动力学性能。

LiNi_0.08Fe_xMn_1.92-xO₄ (x≤0.08) cathode material is rapidly synthesized via solid-state combustion method.The structure,morphology,electrochemical performance,and kinetic performance of the material samples are investigated.The results show that LiNi_0.08Fe_0.05Mn_1.87O₄ cathode material has a cubic spinel structure,which promotes the crystal development of LiMn₂O₄ and the preferential growth of {111},{110} and {100} crystal planes.Some particles form a truncated octahedron shape with highly exposed {111} crystal planes and a small amount of {110} and {100} crystal planes,which significantly improves the rate capability and long cycle life of the material at lower rates (≤5 C).At 25℃,the material has an 106.1 mAh·g^-1 of 1 C initial discharge specific capacity,and a 82.0% of capacity retention rate after 1,000 cycles.At 5 C,it has a 100.1 mAh·g^-1 of initial discharge specific capacity and a 72.8% of capacity retention rate after 2,000 cycles.The lithium ion diffusion coefficient and apparent activation energy of LiNi_0.08Fe_0.05Mn_1.87O₄ material are 1.75×10^-15 cm²·s^-1 and 26.52 kJ·mol^-1,respectively,representing a good Li⁺ migration kinetics.

王紫林(1997-),男,硕士研究生,研究方向为新型化学电源正极材料,1982313433@qq.com。