The surface configuration of pristine layered oxide cathode particles for Li-ion batteries significantly affects the electrochemical behavior, which is generally considered to be a thin rock-salt layer in the surface. Unfortunately, aside from its thin nature and spatial location on the surface, the true structural nature of this surface rock-salt layer remains largely unknown, creating the need to understand its configuration and the underlying mechanisms of formation. Using scanning transmission electron microscopy, we have found a correlation between the surface rock-salt formation and the crystal facets on pristine LiNi_0.80Co_0.15Al_0.05O₂ primary particles. It is found that the originally (014̅) and (003) surfaces of the layered phase result in two kinds of rock-salt reconstructions: the (002) and (111) rock-salt surfaces, respectively. Stepped surface configurations are generated for both reconstructions. The (002) configuration is relatively flat with monatomic steps while the (111) configuration shows significant surface roughening. Both reconstructions reduce the ionic and electronic conductivity of the cathode, leading to a reduced electrochemical performance.

中文翻译：

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层状氧化物阴极表面上依赖于面的岩盐重构

用于锂离子电池的原始层状氧化物阴极颗粒的表面构型会显着影响电化学行为，这通常被认为是表面上的薄岩盐层。不幸的是，除了其稀薄的性质和在表面上的空间位置外，该表层岩盐层的真正结构性质仍然未知，因此需要了解其构造和潜在的形成机理。使用扫描透射电子显微镜，我们发现原始锂镍表面上的盐分形成与晶面之间的相关性LiNi _0.80 Co _0.15 Al _0.05 O ₂初级粒子。发现层状相的原始（014̅）和（003）表面导致两种岩盐重构：分别为（002）和（111）岩盐表面。为这两种重建都生成了阶梯状的表面配置。（002）构造相对平坦，具有单原子台阶，而（111）构造显示出明显的表面粗糙。两种重构都降低了阴极的离子电导率，从而降低了电化学性能。