Uncovering the design principle of conversion-based anode for potassium ion batteries via dimension engineering

Abstract

Conversion-based metal sulfides are regarded as promising anode materials for potassium-ion batteries (PIBs) owing to their high theoretical capacity. Although great advances have been made in PIBs, a comprehensive understanding of state-of-the-art structural design that mitigates the volume expansion upon potassiation/depotassiation remains elusive. Herein, with the established structure-property relationship between the different dimensions and the mechanical degradation with cycling, we suggest the material design rules of conversion anodes for high-performance PIBs via a dimensional engineering approach. Compared with the low-dimensional conversion anode (e.g. spherical and tubular), the multi-dimensional flower like structure formed by interlacing sheets provides the 3D network of ion transport and alleviates the stress concentration, exhibiting improved structural stability and superior electrochemical properties. Synchrotron X-ray tomography demonstrates the interconnected visual ion diffusion paths within the multi-dimensional structure and the decreased morphological complexity. Additionally, modeling of reaction-induced deformation shows that the multi-dimensional design rules of electrode materials can alleviate the uneven distribution of stress during K-ion storage. The material design rules discovered in this study will be proverbially applicable for constructing high capacity and excellent stability conversion-based anode.