Battery performance, such as the rate capability and cycle stability of lithium transition metal oxides, is strongly correlated with the surface properties of active particles. For lithium-rich layered oxides, transition metal segregation in the initial state and migration upon cycling leads to a significant structural rearrangement, which eventually degrades the electrode performance. Here, we show that a fine-tuning of surface chemistry on the particular crystal facet can facilitate ionic diffusion and thus improve the rate capability dramatically, delivering a specific capacity of ∼110 mAh g^–1 at 30C. This high rate performance is realized by creating a nanoscale zirconium-abundant rock-salt-like surface phase epitaxially grown on the layered bulk. This surface layer is spontaneously formed on the Li⁺-diffusive crystallographic facets during the synthesis and is also durable upon electrochemical cycling. As a result, Li-ions can move rapidly through this nanoscale surface layer over hundreds of cycles. This study provides a promising new strategy for designing and preparing a high-performance lithium-rich layered oxide cathode material.

中文翻译：

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用于高速率锂离子电池的富含锂和锰的层状氧化物上的纳米级丰富锆表面层

锂过渡金属氧化物的速率性能和循环稳定性等电池性能与活性颗粒的表面性能密切相关。对于富含锂的层状氧化物，过渡态金属在初始状态下会发生偏析，并且在循环时发生迁移，从而导致结构上的显着重排，最终使电极性能下降。在这里，我们显示出对特定晶面上的表面化学进行微调可以促进离子扩散，从而显着提高倍率能力，在30C时提供约110 mAh g ^–1的比容量。这种高速率性能是通过在层状本体上外延生长形成纳米级的锆含量丰富的岩石盐样表面相来实现的。该表面层是自然形成在锂离子电池上的。合成过程中的⁺扩散晶体学小面，并且在电化学循环中也很耐用。结果，锂离子可以在数百个循环中快速移动通过该纳米级表面层。这项研究为设计和制备高性能的富锂分层氧化物阴极材料提供了一种有希望的新策略。