A New Secondary Battery Based on Carbonate Anion Shuttling in Aqueous Alkaline Electrolyte

ABSTRACT Aqueous secondary batteries (ASBs) employing CO 3 2− electrolyte are rare‐studied but desirable technologies providing eco‐friendly, safe, and cost‐effective energy storage. Herein, novel ASBs based on CO 3 2− anion shuttling between CoNiCu‐C‐LDH/CNT and Cu 2 CO 3 (OH) 2 /CNT in alkaline electrolyte (AACBs) are reported for the first time. During charge/discharge, Co/Ni metals in laminates of cathode subjected to oxidation/reduction while CO 3 2− is reversibly inserted/extracted within interlayers, juxtaposed with CO 3 2− released/consolidated on anode. Integrated into pouch battery, highly reversible electrochemical properties were discovered, powering 2 white LEDs with two AACBs in tandem. The initial capacity at 200 mA g −1 was ∼130 mAh g −1 with stable retention of ∼101 mAh g −1 after 200 cycles. At 400/800 mA g −1 , capacities of ∼94/∼67 mA g −1 were marked respectively. The AACBs hold lowest energy cost, enabling massive production. The excellent CO 3 2− storage can also be reached via Cl − transporting. The findings highlight potential of LDHs on sustainable energy storage/conversion, identifying promising development prospects to new class of aqueous anion batteries (AABs).