A Moisture‐Assisted Rechargeable Mg−CO2 Battery

Abstract

AbstractNew sustainable energy conversion and storage technologies are required to address the energy crisis and CO2 emission. Among various metal–CO2 batteries that utilize CO2 and offer high energy density, rechargeable Mg−CO2 batteries based on earth‐abundant and safe magnesium (Mg) metal have been limited due to the lack of a compatible electrolyte, operation atmosphere, and unambiguous reaction process. Herein, the first rechargeable nonaqueous Mg−CO2 batteries have been proposed with moisture assistance in a CO2 atmosphere. These display more than 250 h cycle life and maintain the discharge voltage over 1 V at 200 mA g−1. Combining with the experimental observations and theoretical calculations, the reaction in the moisture‐assisted Mg−CO2 battery is revealed to be 2 Mg+3 CO2+6 H2O↔2 MgCO3⋅3 H2O+C. It is anticipated that the moisture‐assisted rechargeable Mg−CO2 batteries would stimulate the development of multivalent metal‐CO2 batteries and extend CO2 fixation and utilization for carbon neutrality.