Aqueous Energy Storage Promoted by Mixed Anions between the NiMnCu-LDH Cathode and Hybrid Anode at 0 °C

Aqueous anion energy storage systems (AAEs) represent a promising class of energy technologies that combine high safety, environmental sustainability, and potential for green energy demands. In this work, low-cost NiMnCu-LDH is demonstrated for the first time as a high-performance cathode for AAEs based on Cl-/CO32- storage. As paired with the inexpensive hybrid anode of FeO(OH)/CNT and Bi2O2CO3 in a pouch battery, the AAEs deliver remarkable capacities at 25 and 0 °C, with ∼155 and ∼121 mAh g-1 at 300 mA g-1, respectively, sufficient to power light-emitting diode devices. Dynamic analysis illustrates mixed kinetics in concert: diffusion-controlled and pseudocapacitive processes. The cost-effectiveness of the AAEs derives from the scalable synthesis of both the NiMnCu-LDH cathode and hybrid anode. The outstanding battery performance is attributed to two-dimensional diffusion channels of LDH facilitating reversible intercalation/deintercalation of Cl-/CO32- within interlayers, along with valence transitions of Ni/Mn during charge/discharge cycles. The synergistic effects from mixed anions and the hybrid anode collectively enhance electrochemical performance, in which Cl- and FeO(OH)/CNT provide high capacity, while CO32- and Bi2O2CO3 stabilize cyclicality. These findings highlight the feasibility of the NiMnCu-LDH cathode coupled with the FeO(OH)/CNT and Bi2O2CO3 anode for AAEs to store Cl-/CO32-, offering research insights and development opportunities toward sustainable energy storage technologies.