Stepwise electrochemical reconstruction of a Bi-based anode for enhanced aqueous battery energy storage

Electrochemical reconstruction (ER) is crucial for optimizing aqueous electrode materials, yet the underlying regulatory mechanisms remain largely unexplored. In this study, we developed a stepwise ER technique encompassing both pre-ER and sub-ER stages to enhance the performance of Bi-based anode materials. During the pre-ER process, we uncovered a crucial influence of Bi-ion concentration in the electrolyte on the ER process. This regulation led to a distinct dynamic evolution and significantly superior electrochemical performance compared to unregulated samples. During charge and discharge cycling, the regulated sample exhibited a complex but remarkably stable sub-ER process, characterized by reversible morphological evolution from rigid nanoflakes to flexible rods-a transformation akin to the blooming and closing of flowers. This ER-induced rigid-to-flexible transformation of the anode materials exhibited enhanced compatibility with redox reactions, achieving a superior rate capability of 88.7% capacity retention at 20 A g^-1 and ultralong cyclability with 103.4% capacity retention after 7000 cycles. This marks a pioneering achievement in the controllable regulation of the ER process and paves a new path towards rationally exploring aqueous electrode material.