Feasibility study of gypsum as an electrode binder for building structural batteries: hydration process, electrochemical and mechanical properties

Building structural batteries present broad prospects for future energy storage and zero-energy buildings. However, building structural batteries prepared with cement-based materials currently face technical challenges such as high internal resistance, low energy density, and poor cycle stability. Therefore, through tests such as hydration heat, electrochemical performance, and mechanical properties, this study systematically explores the feasibility and mechanism of using gypsum as an electrode binder to construct building structural batteries. The research results show that gypsum is not electrochemically active and primarily provides mechanical strength in the electrode material. It does not affect the lithium-ion intercalation and deintercalation process in the active material, making it fully feasible as a binder for structural electrodes. As the gypsum content increases, the internal resistance of the electrode material increases, the specific capacity decreases, but the cycling stability improves, and the compressive strength increases. The active material and conductive agent in the electrode promote early gypsum setting and hardening but hinder the later hydration process. When the mass ratio of gypsum to active material to conductive agent is controlled at 8:1:1, the discharge capacity and compressive strength of the electrode material can reach 90 mAh/g and 11.69 MPa, respectively, which shows promise for developing high-performance gypsum-based building structural batteries.