CoMnAl-Layered Double Hydroxide Cathode for High-Performance Aqueous Chloride-Ion Batteries at 0 °C.

Aqueous chloride-ion batteries (ACIBs) are promising energy-storage devices owing to environmental benignity, inherent safety, and abundant seawater electrolytes. However, their development is hindered by limited electrode choices and unsatisfactory electrochemical properties. Herein, we report high-performance ACIBs exploiting CoMnAl-LDH/CNT and BiOCl/CNT as cathode and anode in NaCl/NaOH aqueous electrolyte. CoMnAl-LDH/CNT exhibits a remarkable capacity of 114 mAh g-1 after 200 cycles at 200 mA g-1, with coulombic efficiency exceeding 98%. A specific capacity of 115 mAh g-1 is achieved at 400 mA g-1, with a voltage plateau around 0.8 V. Favorable performance is maintained at 0 °C, with a capacity of ∼142 mAh g-1 (∼89.1% of that at 25 °C). Over 2000 cycles, the capacity degradation per cycle is 0.025%, with lower decay of 0.013% in 200-2000 cycles, suggesting durable discharge capability. Enhanced Cl- storage is derived from fast two-dimensional ion-transport channels and topochemical transformation, facilitating reversible Cl- insertion/extraction and accommodating valence variations of Co/Mn. Interlayer water is crucial for ensuring structure and performance. Synergistic electrode design, electrolyte optimization, and CNTs/Al integration further boost electrochemical performance. This work establishes CoMnAl-LDH-based materials as feasible cathodes for reversible aqueous Cl- storage at 0 °C, highlighting great potential for future anion-shuttle batteries.