In Situ Engineering of the Core–Shell Ag@Cu Structure on Porous Nanowire Arrays for High Energy and Stable Aqueous Ag–Bi Batteries

There is an urgent need to design practical aqueous rechargeable batteries (ARBs) with high energy density and long cycle life, using state-of-the-art cathode materials with low toxicity and environmental friendly nature. In virtue of the stable discharge potential and high energy density, silver (Ag) presents a huge perspective in the field of aqueous batteries. Herein, the paradigm of a novel core–shell Ag@Cu structure in situ Cu porous nanowire array skeleton (Ag@Cu NWA) is designed as the efficient cathode of an ARB. Benefiting from the ultrathin metal Ag shell (∼7 nm) and the high-conductivity metal Cu core, along with the robust porous nanowire framework, the as-obtained Ag@Cu NWA cathode integrates the features of maximal utilization of the active material, superior charge transfer, and exceptional electrolyte accessibility, exhibiting a considerable capacity of 1.79 mA h cm–2 (458 mA h g–1: 92.3% of theoretical capacity) and remarkable cycling stability (83.6% retention after 5000 cycles). Furthermore, a well-designed aqueous rechargeable Ag//Bi full cell is fabricated using the Ag@Cu NWA cathode, achieving high capacity (1.57 mA h cm–2 at 2 mA cm–2) with excellent rate performance (92.9% at 20 mA cm–2) and an admirable energy density of 16.96 mW h cm–3. This work puts forward a prospective strategy to construct viable new types of ARB materials based on multimetal nanocomposites, showing great potential for practical electronic devices.