铝掺杂对高镍无钴LiNi0.95Mn0.05O2正极材料结构与性能的影响

采用固相法合成了铝掺杂的层状高镍无钴LiNi_0.95Mn_0.05O₂正极材料,并利用结构分析方法和电化学测试手段研究了铝掺杂对LiNi_0.95Mn_0.05O₂正极材料晶体结构和电化学性能的影响。结果表明,Al均匀地掺杂到了正极材料二次颗粒体相中,不仅使材料晶胞参数发生了变化,还降低了材料的Li⁺/Ni²⁺混排程度。掺杂1%铝可以提高材料的长循环性能,这归因于掺杂样品中的Al能有效抑制材料在充电过程中的H2→H3相变程度。相比于未掺杂的样品,铝掺杂样品在1C、2.7~4.3 V的测试条件下循环300圈后,其容量保持率提高了11.3%。但Al³⁺的非电化学活性会降低材料的倍率性能。

Effect of Al-Doping on Structure and Performance of LiNi0.95Mn0.05O2 Cathode Material

Al-doped layered LiNi_0.95Mn_0.05O₂ cathode was synthesized by solid-state method, and the effect of Al-doping on crystal structure and electrochemical properties of LiNi_0.95Mn_0.05O₂ cathode was investigated by structural analysis and electrochemical testing. The results show that the Al dopant is uniformly doped into the surface and bulk of secondary particles of cathodes, which not only induces the variations of lattice parameters, but also reduces the mixing degree of Li+/Ni²⁺ in cathode. Cathode material with 1% Al-doping can have an enhanced long-term cycling performance, which is ascribed to the restraint of transitions from H2 to H3 phase by Al dopant during the charging process. In comparison to the undoped sample, the Al-doped sample has its capacity retention improved by 11.3% after 300 cycles at 1C and 2.7-4.3 V. However, the non-electrochemical activity of Al3+ reduces the rate capability of the material.