Unraveling enhanced conversion reversibility of regulated Cu₄SnS₄ composites for superior lithium storage

High-capacity electrodes based on multiple reaction mechanisms are promising for lithium storage, but the inferior conversion reversibility limits the practical application. Herein, the Cu-Sn-S (CTS) electrodes based on conversion-alloying mechanisms are synthesized with abundant Cu₄SnS₄ (75.98%) and beneficial Cu_7.2S₄ phases. The regulated composition and core-shell nanostructures can effectively mitigate the volume change and improve the lithiation performance of CTS upon cycling. Moreover, the composition evolution of CTS is comprehensively tracked via various in-situ tests, revealing that the abundant Cu₄SnS₄ and the formed Cu₃Sn after lithiation are the key factors to induce uniform phase distribution and enhanced conversion reversibility, which is confirmed by theoretical calculations. This work sheds light on the reaction process of electrodes based on multiple lithiation mechanisms, which could inspire the development of analogous energy materials.