Synergistic Engineering of Sulfur Vacancies and Heterointerfaces in Copper Sulfide Anodes for Aqueous Zn-Ion Batteries with Fast Diffusion Kinetics and an Ultralong Lifespan

Aqueous Zn-ion batteries (AZIBs) are promising candidates for implementing large-scale energy storage, but the adverse side reactions and unsatisfactory cycle life brought by Zn-metal anodes limit their potential in applications. Herein, an ingenious synthesized CuS1-x@polyaniline (PANI) is proposed as an attractive conversion-type Zn-metal-free anode for AZIBs, in which appropriate S-vacancies and PANI heterointerfaces can be simultaneously constructed. This "killing three birds with one stone" strategy stabilizes the anode structure by utilizing organic-inorganic heterointerfaces and enhances Zn2+ storage, benefiting from abundant S-vacancies, as well as initiating fast Zn2+ transport kinetics based on the joint effect of the two. Operando X-ray absorption fine structure and synchrotron X-ray diffraction further reveal the highly reversible conversion reaction of CuS1-x@PANI via a distinct crystallization-amorphous transformation mechanism. These features endow CuS1-x@PANI with sufficient zinc-ion storage capacity (215 mA h g(-1) at 100 mA g(-1)) and reliable current abuse tolerance (154.3 mA h g(-1) at 1 A g(-1) after 1000 cycles). Moreover, when matched with the optimized ZnxMnO2 cathode, the full battery achieves a record-high cycling performance of 10 000 cycles (80% capacity retention) at a superhigh current density of 10 A g(-1). This study provides new opportunities for developing high-performance rocking-chair AZIBs.