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Lithium rich layered oxide xLi2MnO3∙(1−x)LiMO2 (M = Mn, Co, Ni, etc.) materials are promising cathode materials for next generation lithium ion batteries. However, the understanding of their electrochemical kinetic behaviors is limited. In this work, the phase separation behaviors and electrochemical kinetics of 0.5Li2MnO3∙0.5LiCoO2 materials with various Li2MnO3 domain sizes were studied. Despite having similar morphological, crystal and local atomic structures, materials with various Li2MnO3 domain sizes exhibited different phase separation behavior resulting in disparate lithium ion transport kinetics. For the first few cycles, the 0.5Li2MnO3∙0.5LiCoO2 material with a small Li2MnO3 domain size had higher lithium ion diffusion coefficients due to shorter diffusion path lengths. However, after extended cycles, the 0.5Li2MnO3∙0.5LiCoO2 material with larger Li2MnO3 domain size showed higher lithium ion diffusion coefficients, since the larger Li2MnO3 domain size could retard structural transitions. This leads to fewer structural rearrangements, reduced structural disorders and defects, which allows better lithium ion mobility in the material.

Layered-layered composite oxides of the form xLi2MnO3·(1−x) LiMO2 (M = Mn, Co, Ni) have received much attention as candidate cathode materials for lithium ion batteries due to their high specific capacity (>250mAh/g) and wide operating voltage range of 2.0–4.8 V. However, the cathode materials of this class generally exhibit large capacity fade upon cycling and poor rate performance caused by structural transformations. Since electrochemical properties of the cathode materials are strongly dependent on their structural characteristics, the roles of these components in 0.5Li2MnO3·0.5LiCoO2 cathode material was the focus of this work. In this work, the influences of Li2MnO3 domain size and current rate on electrochemical properties of 0.5Li2MnO3·0.5LiCoO2 cathodes were studied. Experimental results obtained showed that a large domain size provided higher cycling stability. Furthermore, fast cycling rate was also found to help reduce possible structural changes from layered structure to spinel structure that takes place in continuous cycling.

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Silica is a promising anode material for high‐energy lithium‐ion batteries (LIBs), but it suffers from several problems. The main issue is low electrical conductivity, which limits its practical applications. Fabricating silica–carbon nanocomposites (C/SiO2) can significantly enhance the electrochemical performance of these materials. In this work, the authors perform first principles calculations to investigate the interfacial properties and electronic structure between carbon and small Si‐based molecules. The simulations suggest that C/SiO2 and C/SiO interfaces facilitate the lithiation process, providing additional lithium storage pathways in addition to the typical phase transitions of SiO2 and SiO. In addition, a simple production and ready to scale‐up method is proposed to fabricate a nanocomposite possessing rich C/SiOx (1 ≤ x ≤ 2) interfaces. The resulting nanocomposite anode has a stable capacity of ~650 mAh g‐1 at a current density of 1 A g‐1 after 1500 cycles with >95% capacity retention. This work provides a better understanding of the Li ion storage mechanisms of C/SiOx. Adding carbon not only increases electrical conductivity and strength, but also provides new pathways for Li‐ion transport through their interfaces contributing to the enhanced stability and electrochemical properties of inexpensive non‐conducting/oxide‐based energy storage materials.

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