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Na-substitution induced oxygen vacancy achieving high transition metal capacity in commercial Li-rich cathode
Nano Energy ( IF 17.6 ) Pub Date : 2020-11-24 , DOI: 10.1016/j.nanoen.2020.105622
Quanxin Ma , Zaijun Chen , Shengwen Zhong , Junxia Meng , Fulin Lai , Zhifeng Li , Chen Cheng , Liang Zhang , Tiefeng Liu

High-capacity and low-cost Li-rich layered Mn-based oxides (LLMOs) hold the great promise for next-generation lithium ion battery cathode but LLMOs still encounter grand challenges in voltage decay and gas release. Here, we proposed a simple but effective as well as scalable approach of creating surface oxygen vacancies (OVs) and simultaneously enhancing structural stability. A series of Li1.2–2xNaxMn0.56Ni0.16Co0.08O2 (x = 0, 0.05, 0.1 and 0.2) cathode materials are synthesized, based on Na-pre-embedded precursor and nonstoichiometric lithiation processes, to render the OVs confirmed by synchrotron radiation analysis. First-principles calculations suggest that the architecture induced by surface OVs obviously affects the local Mn coordination environments and enhances the structural stability. Meanwhile, enlarged Li layer spacing by Na doping enables increased Li diffusion, decreased voltage polarization, and enhanced structural stability. Accordingly, the optimized Na0.1-LLMO cathode delivers highly initial coulombic efficiency of 84.2% compared to the pristine one (79.9%) and remarkable electrochemical behaviors in terms of cycling stability, voltage retention and rate performance. Pouch cell investigation further verifies the practical applicability of Na-doped LLMO cathode materials to scale up.



中文翻译:

Na取代引起的氧空位在商用富锂阴极中实现了高过渡金属容量

高容量和低成本的富锂层状锰基氧化物(LLMO)为下一代锂离子电池阴极带来了广阔前景,但LLMO在电压衰减和气体释放方面仍面临巨大挑战。在这里,我们提出了一种简单但有效且可扩展的方法来创建表面氧空位(OVs)并同时增强结构稳定性。一系列Li 1.2–2x Na x Mn 0.56 Ni 0.16 Co 0.08 O 2基于预嵌入的Na前驱体和非化学计量的锂化过程,合成了(x = 0、0.05、0.1和0.2)阴极材料,以通过同步加速器辐射分析确定OV。第一性原理计算表明,表面OVs诱导的结构明显影响了局部Mn配位环境并增强了结构稳定性。同时,通过Na掺杂来扩大Li层间距使得能够增加Li扩散,降低电压极化并增强结构稳定性。因此,优化的Na 0.1-LLMO阴极的原始库仑效率为84.2%,而原始阴极的库仑效率为79.9%,并且在循环稳定性,电压保持率和倍率性能方面具有出色的电化学性能。袋式电池研究进一步验证了Na掺杂的LLMO阴极材料在扩大规模方面的实际适用性。

更新日期:2020-12-10
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