The strategies to improve the layered-structure cathodes for aqueous multivalent metal-ion batteries

Aqueous multivalent metal-ion batteries (AMMIBs), with their unique characteristics such as high safety, low cost, and multiple electron transfers, have been widely applied in the fields of wearable devices, consumer electronics, and electric vehicles. Layered-structure materials are regarded as promising electrode materials for AMMIBs because of their tunable interlayer spacing and the ability to accommodate other guest ions or molecules. However, their large-scale application is impeded by several issues, including the dissolution, structural instability, low conductivity, and poor electrochemical properties of active materials. This review highlights various strategies aimed to solve these issues for layered-structure cathode materials. It begins with a brief introduction on the fundamental characteristics of the AMMIBs and challenges faced by the layered-structure materials. Subsequently, several effective strategies are elaborated in detail from the point of view of morphology, structure of the cathodes, and electrolyte to provide further insights into the design and optimization of high-performance AMMIBs. Lastly, a brief summary of the strengths and weaknesses of the above strategies is presented and focus is placed on the possible research direction in this field.