Nickel‐rich layered oxide cathodes with the composition LiNi_1−x−yCo_xMn_yO₂ (NCM, (1−x−y) ≥ 0.6) are under intense scrutiny recently to contend with commercial LiNi_0.8Co_0.15Al_0.05O₂ (NCA) for high‐energy‐density batteries for electric vehicles. However, a comprehensive assessment of their electrochemical durability is currently lacking. Herein, two in‐house cathodes, LiNi_0.8Co_0.15Al_0.05O₂ and LiNi_0.7Co_0.15Mn_0.15O₂, are investigated in a high‐voltage graphite full cell over 1500 charge‐discharge cycles (≈5–10 year service life in vehicles). Despite a lower nickel content, NCM shows more performance deterioration than NCA. Critical underlying degradation processes, including chemical, structural, and mechanical aspects, are analyzed via an arsenal of characterization techniques. Overall, Mn substitution appears far less effective than Al in suppressing active mass dissolution and irreversible phase transitions of the layered oxide cathodes. The active mass dissolution (and crossover) accelerates capacity decline with sustained parasitic reactions on the graphite anode, while the phase transitions are primarily responsible for cell resistance increase and voltage fade. With Al doping, on the other hand, secondary particle pulverization is the more limiting factor for long‐term cyclability compared to Mn. These results establish a fundamental guideline for designing high‐performing Ni‐rich NCM cathodes as a compelling alternative to NCA and other compositions for electric vehicle applications.

中文翻译：

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锂离子电池层状氧化物阴极中的锰与铝：长期循环性的综合评估

成分为LiNi _{1- x - y} Co _x Mn _y O ₂（NCM，（1- x - y）≥0.6）的富镍层状氧化物阴极最近受到严格审查，以应对商业化的LiNi _0.8 Co _0.15 Al _0.05 O ₂（NCA）用于电动汽车的高能量密度电池。然而，目前缺乏对其电化学耐久性的全面评估。在此，两个内部阴极LiNi _0.8 Co _0.15 Al _0.05 O ₂和LiNi _0.7 Co_0.15锰_0.15 O ₂在1500个充放电循环（≈5-10年的车辆使用寿命）中，对一个高压石墨满电池进行了研究。尽管镍含量较低，但NCM比NCA表现出更多的性能下降。关键的潜在降解过程，包括化学，结构和机械方面，通过大量表征技术进行了分析。总体而言，Mn取代在抑制活性物质溶解和层状氧化物阴极不可逆相变方面似乎远不如Al有效。活性物质的溶解（和交叉）加速了石墨阳极上持续的寄生反应引起的容量下降，而相变主要负责电池电阻的增加和电压的衰减。另一方面，如果使用Al掺杂，与Mn相比，二次颗粒粉碎是长期可循环性的更大限制因素。这些结果为设计高性能的富镍NCM阴极奠定了基本指导方针，可作为NCA和电动汽车应用中其他成分的引人注目的替代品。