Rationally Designed Metal Sulfide-LDH Heterostructures for High Energy Aqueous Zn-Based Battery Cathodes

Rechargeable alkaline Zn-Ni(Co) batteries offer high output voltage and intrinsic safety; however, their practical deployment is hindered by sluggish cathodic kinetics and parasitic side reactions, which limit both energy density and power capability. Here, the design and synthesis of a crystalline-amorphous heterostructure cathode combining mixed Ni and Co sulfides (MS) with Ni-Co layered double hydroxides (LDHs) is reported. This design synergistically leverages the electrical conductivity and structural adaptability of metal sulfides with the expanded interlayer spacing and ion transport channels of LDHs. The engineered MS-LDH cathode exhibits abundant electroactive sites, enhanced hydroxide ion adsorption, and accelerated ion diffusion kinetics, delivering a high specific capacity of 773 mAh g^-1 at 2 A g^-1. When paired with a chitosan-in-PVA gel-coated Zn anode (Zn@CP), the aqueous Zn@CP||MS-LDH battery, delivers an ultrahigh specific energy of 1309 Wh kg^-1-among the highest reported for similar systems-and a specific power of 3.44 kW kg^-1, comparable to pseudocapacitors. Moreover, the battery demonstrates excellent rate capability and long-term cycling stability. These results highlight the promise of earth-abundant heterostructured materials in overcoming critical limitations of aqueous Zn-based batteries, offering a promising pathway toward sustainable, high-performance energy storage technologies.