Layered electrode materials for non-aqueous multivalent metal batteries

Abstract

The global transition to clean energy production accelerates the necessity for efficient energy storage solutions. Lithium-ion batteries (LIBs), developed considerably over the past three decades, have been widely applied in portable electronics and electric vehicles. Nevertheless, the application of LIBs in large-scale energy storage applications is restricted by the Li resource scarcity, high-cost raw materials, and severe safety issues, which thus triggers the development of new battery chemistries beyond Li⁺. In this regard, multivalent metal batteries (MVMBs, e.g., Zn, Mg, and Al batteries) are promising alternatives owing to the advantages brought by the direct use of corresponding metals as anodes, such as high elemental abundance, low anode redox potential, multielectron redox capability, and facile metal stripping and plating chemistry. However, MVMBs suffer from the lack of available cathodes for efficiently accommodating multivalent metal ions (i.e., Zn²⁺, Mg²⁺, and Al³⁺), which originates from the strong electrostatic interactions between charge carrier ions and cathodes. Promising cathode candidates for MVMBs to address this challenge are layered electrode materials, whose structures can be engineered with versatile approaches to regulate the charge-storage behaviour. Here, layered electrode materials used for non-aqueous MVMB cathodes are thoroughly reviewed. We first introduce the cell configurations and the thus-far developed anode–electrolyte–cathode chemistries for non-aqueous MVMBs. Recent progress in the exploration of layered materials for non-aqueous MVMBs is subsequently summarized. Emphasis is put on examining the employed structure engineering strategies and their effects on both the intrinsic properties and electrochemical behaviours of layered electrode materials. Finally, perspectives on the challenges and future directions in this research field are provided with aspects to the cathode structure engineering, performance assessment, and device demonstration.