Copper metal electrode reversibly hosts fluoride in a 16 m KF aqueous electrolyte.

Fluoride is a promising charge carrier for batteries due to its high charge/mass ratio and small radius. Here, we report commercial copper powder exhibits a reversible capacity of up to 222 mA h g-1 in a saturated electrolyte of 16 m KF. This electrolyte suppresses dissolution of CuF2, the charged product. Furthermore, the KF solid comprised in the Cu electrode facilitates a high initial capacity. Our results showcase the potential of aqueous fluoride batteries using copper as an electrode.

From Copper to Basic Copper Carbonate: A Reversible Conversion Cathode in Aqueous Anion Batteries.

Dual-ion batteries that use anions and cations as charge carriers represent a promising energy-storage technology. However, an uncharted area is to explore transition metals as electrodes to host carbonate in conversion reactions. Here we report the reversible conversion reaction from copper to Cu2 CO3 (OH)2 , where the copper electrode comprising K2 CO3 and KOH solid is self-sufficient with anion-charge carriers. This electrode dissociates and associates K+ ions during battery charge and discharge. The copper active mass and the anion-bearing cathode exhibit a reversible capacity of 664 mAh g-1 and 299 mAh g-1 , respectively, and relatively stable cycling in a saturated mixture electrolyte of K2 CO3 and KOH. The results open an avenue to use carbonate as a charge carrier for batteries to serve for the consumption and storage of CO2 .