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

Aqueous secondary batteries (ASBs) employing CO₃ ^2- electrolyte are rare-studied but desirable technologies providing eco-friendly, safe, and cost-effective energy storage. Herein, novel ASBs based on CO₃ ^2- anion shuttling between CoNiCu-C-LDH/CNT and Cu₂CO₃(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 CO₃ ^2- is reversibly inserted/extracted within interlayers, juxtaposed with CO₃ ^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 CO₃ ^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).