High-Strength agarose gel electrolyte enables long-endurance wearable Al-air batteries with greatly suppressed self-corrosion

Al-air batteries (AABs) are a great option for outdoor wearable electronics due to their high theoretical energy density (8100 Wh kg−1), huge industrial reserves and easy recyclability of Al, but suffer from severe self-corrosion, low Al utilization and harmful liquid leakage. Herein, we first devise a high-strength agarose gel electrolyte (AGE) that combines high toughness and super solution carrying capacity, for the construction of wearable AABs with high energy density, safety, easy assembly and greatly suppressed self-corrosion. The rigid AGEs convert the traditional Al/liquid interface into an Al/quasi-solid interface, thus leading to the formation of a Sn-dominated passivation layer that drastically inhibits the self-corrosion of Al. The in-depth failure mechanism study of AGE-based AAB coin cells demonstrates that three most critical factors affecting the discharge behavior of Al anodes are in order: H2 accumulation, working current density and OH− replenishment. On this basis, the optimized large-area soft-package AAB (10 cm2) shows a 20.1-hour discharge duration and a specific capacity of 2148.5 mAh g−1 (2766.9 Wh kg−1), outperforming those of the state-of-the-art AABs based on other gel electrolytes. More impressively, a practically useful wearable AAB pack is further prepared to drive the LED array and a smart phone.