High‐Capacity and High‐Rate Discharging of a Coenzyme Q₁₀‐Catalyzed Li–O₂ Battery

Abstract

Abstract Discharging of the aprotic Li–O 2 battery relies on O 2 reduction to insulating solid Li 2 O 2 , which can either deposit as thin films on the cathode surface or precipitate as large particles in the electrolyte solution. Toward realizing Li–O 2 batteries with high capacity and high rate capability, it is crucially important to discharge Li 2 O 2 in the electrolyte solution rather than on the cathode surface. Here, a soluble electrocatalyst of coenzyme Q 10 (CoQ 10 ) that can efficaciously drive solution phase formation of Li 2 O 2 in current benchmark ether‐based Li–O 2 batteries is reported, which would otherwise lead to Li 2 O 2 surface‐film growth and premature cell death. In the range of current densities of 0.1–0.5 mA cm −2 areal , the CoQ 10 ‐catalyzed Li–O 2 battery can deliver a discharge capacity that is ≈40–100 times what the pristine Li–O 2 battery could achieve. The drastically enhanced electrochemical performance is attributed to the CoQ 10 that not only efficiently mediates the electron transfer from the cathode to dissolve O 2 but also strongly interacts with the newly formed Li 2 O 2 in solution retarding its precipitation on the cathode surface. The mediated oxygen reduction reaction and the bonding mechanism between CoQ 10 and Li 2 O 2 are understood with density functional theory calculations.