Layered transition metal oxides are widely used as cathode materials for lithium- and sodium-ion batteries. Their high theoretical capacity is predicated on the complete extraction of the intercalant cations between the transition metal oxide layers. However, deep charge exceeding 70% of the theoretical capacity induces collapse of the interlayer, which leads to the intergranular cracking of the secondary particles commonly used in the electrode. Such irreversible microstructural change is a primary cause of the capacity degradation that limits the practical realization of the material's full theoretical capacity. One approach to mitigate the layer collapse is through the introduction of pillar ions in the interlayer. This work investigates the pillaring effect on the function of the layered transition metal oxides as battery cathodes.
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