A Comprehensive Strategy Enables High‐Loading BiOBr@BiOIO3 Cathodes for Quasi Ah‐Level Aqueous Zn‐Ion Batteries

Abstract Aqueous Zn‐ion batteries (AZIBs) recently have attracted broad attention. To achieve high energy density of AZIBs, constructing high‐loading cathodes is the prerequisite. However, the cycling stability of high‐loading cathodes still faces great challenges. Herein, a comprehensive strategy is proposed to improve the structural stability of the cathode material and mechanical stability of the high‐loading cathode. The BiOBr@BiOIO 3 heterostructure are successfully constructed via sharing the interfacial oxygen atoms, in which the interfacial effect can effectively enhance the reaction dynamics and structural stability. Meanwhile, a biomimetic binder is skillfully designed via in situ dual cross‐linking between guar gum and cation ions to achieve the application of water‐based and sustainable polymer binder in AZIBs. Density functional theory calculations demonstrate the guar gum possesses strong affinity toward BiOBr@BiOIO 3 to firmly adhere the active materials. Quantitative nanomechanic technology visually demonstrates the robust mechanical properties of the as‐obtained BiOBr@BiOIO 3 cathode. As a result, when the active material loading increases to as high as 100.71 mg cm −2 , an ultrahigh areal capacity of 20.02 mAh cm −2 can be achieved. Specially, a quasi‐Ah‐level (0.244 Ah) pouch‐type cell with a loading of 1.17 g can be constructed, showing the practical application potential.