A Rocking-chair Rechargeable Seawater Battery.

Seawater batteries are attracting continuous attention because seawater as an electrolyte is inexhaustible, eco-friendly, and free of charge. However, the rechargeable seawater batteries developed nowadays show poor reversibility and short cycle life, due to the very limited electrode materials and complicated yet inappropriate working mechanism. Here, we propose a rechargeable seawater battery that works through a rocking-chair mechanism encountered in commercial lithium ion batteries, enabled by intercalation-type inorganic electrode materials of open-framework-type cathode and Na-ion conducting membrane-type anode. The rechargeable seawater battery achieves a high specific energy of 80.0 Wh/kg at 1,226.9 W/kg and a high specific power of 7,495.0 W/kg at 23.7 Wh/kg. Additionally, it exhibits excellent cycling stability, retaining 66.3% of its capacity over 1,000 cycles. This work represents a promising avenue for developing sustainable aqueous batteries with low costs.