Stabilized Li-Rich Layered Oxide Cathode by a Spontaneously Formed Yb and Oxygen-Vacancy Rich Layer on the Surface,Small

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Stabilized Li-Rich Layered Oxide Cathode by a Spontaneously Formed Yb and Oxygen-Vacancy Rich Layer on the Surface
Small ( IF 13.0 ) Pub Date : 2023-10-11 , DOI: 10.1002/smll.202307419
Quan Li _{1,

2} , Hong Wang _{1,

2,

3} , Guan Wang _{1,

2} , Fanjie Xia _{1,

2} , Weihao Zeng _{1,

2} , Haoyang Peng _{1,

2} , Ganggang Ma _{1,

2} , Anan Guo _{1,

2} , Ruifeng Dong _{1,

2} , Jinsong Wu _{1,

2}

Affiliation

Li-rich layered oxides (LLOs) are among the most promising cathode materials with high theoretical specific capacity (>250 mAh g⁻¹). However, capacity decay and voltage hysteresis due tostructural degradation during cycling impede the commercial application of LLOs. Surface engineering and element doping are two methods widely applied tomitigate the structural degradation. Here, it is found that trace amount lanthanide element Yb doping can spontaneously form a surficial Yb-rich layer with high density of oxygen vacancy on the LLO-0.3% Yb (Li_1.2Mn_0.54Co_0.13-xYb_xNi_0.13O₂ where x = 0.003) cathodes, which mitigating lattice oxygen loss and the non-preferred layered-to-spinel-to-rock salt tri-phase transition. Meanwhile, there are also some Yb ions doped into the lattice of LLO, which enhance the binding energy with oxygen and stabilize the lattice in grain interior during cycling. The dual effects of Yb doping greatly mitigate the structure degradation during cycling, and facilitate fast diffusion of lithium ions. As a result, the LLO-0.3% Yb sample achieves significantly improved cycling stability, with a capacity retention of 84.69% after 100 cycles at 0.2 C and 84.3% after 200 cycles at 1 C. These finding shighlight the promising rare element doping strategy that can have both surface engineering and doping effects in preparing LLO cathodes with high stability.

中文翻译：

通过表面自发形成的 Yb 和富氧空位层来稳定富锂层状氧化物阴极

富锂层状氧化物（LLO）是最有前途的正极材料之一，具有高理论比容量（>250 mAh g ^-1 ）。然而，循环过程中结构退化导致的容量衰减和电压滞后阻碍了 LLO 的商业应用。表面工程和元素掺杂是广泛应用于减轻结构退化的两种方法。研究发现，微量镧系元素Yb掺杂可以在LLO-0.3% Yb（Li _1.2 Mn _0.54 Co _0.13-x Yb _x Ni _0.13 O ₂ ）上自发形成具有高氧空位密度的表面富Yb层，其中x = 0.003）阴极，可减轻晶格氧损失和非优选的层状到尖晶石到岩盐的三相转变。同时，也有一些Yb离子掺杂到LLO的晶格中，增强了与氧的结合能，并在循环过程中稳定了晶粒内部的晶格。 Yb掺杂的双重效应极大地减轻了循环过程中的结构退化，并促进锂离子的快速扩散。结果，LLO-0.3% Yb 样品显着提高了循环稳定性，在 0.2 C 下 100 次循环后容量保持率为 84.69%，在 1 C 下 200 次循环后容量保持率为 84.3%。这些发现凸显了稀有元素掺杂策略的前景。在制备高稳定性LLO阴极时可以兼具表面工程和掺杂效应。

更新日期：2023-10-11

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