Advanced High Energy Density Secondary Batteries with Multi-Electron Reaction Materials

Nowadays, various types of electrical facilities and the elevated demand for the wider application of electronic devices in future smart cities are calling for next-generation batteries of higher energy density, superior rate capability, and extended cycling performance. Multi-electron systems, based on related reactions and materials, have been considered as promising battery systems for future applications, and massive attempts have been made to achieve their practical use. Therefore, a comprehensive realization of multi-electron reactions is imperative for the exploitation of innovative multi-electron materials and steps forward to higher battery performances. In this review, the fundamental conception of multi-electron reactions and their application bottlenecks are given from both theoretical principles and practice. Multi-electron materials generally face problems from both thermodynamics and kinetics, including material dissolution, low intrinsic conductivity, low ion transport, etcetera, which seriously hinder their future application. Given all this, current prioritization schemes are summarized, thus making a better understanding of the working mechanisms of the modification methods and inspiring prospects of practical multi-electron materials. Introducing multi-electron reactions is one main solution to enhancing the battery's energy density. Herein, multi-electron materials and their prioritization schemes are highlighted, and the newly proposed mechanisms are revealed, providing a more comprehensive, integrated, objective, and systematic evaluation. By concluding existing strategies, some unsolved questions are raised and opportunities for future multi-electron systems are highlighted. image