Highly Effective Electrolytes Toward High-Performance Aluminum/Seawater Batteries

Graphical A type of Al/H 2 O batteries has been developed using simulated seawater at an appropriate pH and added with PAA as a new electrolyte, which simultaneously greatly retards the self-corrosion of the Al anode and increases the electrocatalytic activity toward the HER. The optimized battery shows energy density higher than reported batteries and power density superior to reported metal/H 2 O batteries. The poor performance of metal/water batteries caused by self-corrosion of anodes and low catalytic activity of cathodes has been a long-standing challenge, greatly limiting their practical applications, in particular the underwater unmanned vehicle (UUV) application. We have fabricated an Al/seawater battery using simulated seawater with an appropriate pH and added with polyacrylic acid (PAA) as the electrolyte. This electrolyte simultaneously greatly retards self-corrosion of the Al anode by in situ forming a PAA-Al 3+ complex film on it and increases the electrocatalytic activity toward the hydrogen evolution reaction by improving the electronic structure of Pt. When utilizing the multielement-doped Al sheet as the anode and nickel foam supported loading-amount-optimized Pt/C catalyst as the cathode and adopting the developed new electrolyte, the obtained Al/H 2 O battery exhibits an energy density of 2271 Wh kg −1 , which is the highest among those of all the reported batteries, and a power density of 20.87 mW cm −2 , which outperforms all the reported metal/H 2 O batteries. This work not only develops a new type of high-performance Al/H 2 O batteries for practical applications such as UUVs, but provides scientific insight into the design of superior electrolytes, which could be further extended for improving the performances of various metal batteries.