Multidimensional Nonstoichiometric Electrode Materials for Electrochemical Energy Conversion and Storage

摘要

Nonstoichiometry plays an important role in determining physicochemical properties such as conductivity, activity, and stability due to the composition-induced change in phase, local atomic environment, and electronic structure. A variety of materials with nonstoichiometry have emerged in electrochemical energy conversion and storage, which necessitates a solid understanding of their formation mechanism and structure-function relationship. This review presents a summary of the progress made in this emerging field, starting from the introduction of the multiscale top-down and bottom-up strategies for generating nonstoichiometry and the related characterization methodologies. Then, representative nonstoichiometric materials (NMs) are discussed in properties and merits, with selected examples of each material category. A special focus is placed on the dimensionality from atomic sites to surface/interfaces, grains, microstructure, and hierarchical macroscale. After that, recent advances are overviewed for the use of exemplified NMs in electrocatalysis (i.e., oxygen reduction/evolution, hydrogen evolution, and nitrogen reduction) and batteries (i.e., Li/Na/Zn batteries). The review is concluded with a summary highlighting the beneficial effects of NMs and a perspective on further research to address remaining issues.