【摘要】 采用固相燃烧法制备了单晶多面体尖晶石型LiMn_1.94B_0.06O₄正极材料,利用X射线衍射（XRD）、扫描电镜（SEM）、透射电镜（TEM）以及充放电测试等手段,对其晶体结构和电化学性能等进行了表征。结果表明,B掺杂没有改变尖晶石型LiMn₂O₄的晶体结构,促进了（440）和（400）晶面的优先生长,形成了高暴露的（111）晶面及少部分（110）和（100）晶面的单晶多面体LiMn_1.94B_0.06O₄晶粒,减少了Mn的溶解和提供了更多的锂离子扩散通道,其晶粒尺寸在160～350 nm之间。在10C、25℃的条件下,LiMn_1.94B_0.06O₄电极的首次放电比容量可达到103.0 mAh·g^-1,2 000次循环后,表现出较好的容量保持率（57.7%）;在15C高倍率下,LiMn_1.94B_0.06O₄仍然保持了67.1 mAh·g^-1的首次放电比容量,1 500次循环后,仍能维持46.2%的容量保持率;在1C、55℃的条件下,其初始放电比容量高达125.2 mAh·g^-1,表现出良好的高温性能。B掺杂能够有效提高尖晶石型LiMn₂O₄的高倍率性能和循环寿命,稳定晶体结构,抑制Jahn-Teller效应和缓解Mn的溶解。更多还原

【Abstract】 A single crystal polyhedron LiMn_1.94B_0.06O₄ cathode material was prepared by a solid-state combustion synthesis,their structural and electrochemical properties were characterized by X-ray diffraction （XRD）,scanning electron microscopy （SEM）,transmission electron microscopy （TEM） and charge-discharge test.The results show that B-doping did not change the crystal structure of spinel LiMn₂O₄,and it could promote the preferential growth of （440）and （400） crystal facets.Inducing the formation of the single crystal polyhedron LiMn_1.94B_0.06O₄ material with the highly exposed （111） facets and a small part of （110） and （100） facets,as well as a particle size of 160～350 nm,which enabled minimal Mn dissolution and provided more lithium ions channels.The LiMn_1.94B_0.06O₄delivered the initial discharge capacity of 103 mAh·g^-1with a good capacity retention rate of 57.7%after 2 000 cycles at 10C and25℃.At high current rate of 15C,it showed the initial discharge capacity of 67.1 mAh·g^-1,and the capacity retention rates of 46.2%was obtained after 1 500 cycles.Moreover,at 1C and high temperature of 55℃,the initial discharge capacity of 125.2 mAh·g^-1was also maintained,showing good high temperature performance.The B-doping can effectively improve the high rate performance and cycle life of spinel LiMn₂O₄,stabilize the crystal structure,inhibit the Jahn-Teller effect and relieve the Mn dissolution.更多还原