LiCoO₂-catalyzed electrochemical oxidation of Li₂CO₃

Lithium carbonate (Li₂CO₃) is very common in various types of lithium (Li) batteries. As an insulating by-product of the oxygen reduction reaction on the cathode of a Li–air battery, it cannot be decomposed below 4.75 V (vs. Li⁺/Li) during recharge and leads to a large polarization, low coulombic efficiency, and low energy conversion efficiency of the battery. On the other hand, more than 10% of the Li ions from the cathode material are consumed during chemical formation of a Li-ion battery, resulting in low coulombic efficiency and/or energy density. Consequently, lithium compensation becomes essential to realize Li-ion batteries with a higher energy density and longer cycle life. Therefore, reducing the oxidation potential of Li₂CO₃ is significantly important. To address these issues, we show that the addition of nanoscaled LiCoO₂ can effectively lower this potential to 4.25 V. On the basis of physical characterization and electrochemical evaluation, we propose the oxidization mechanism of Li₂CO₃. These findings will help to decrease the polarization of Li–air batteries and provide an effective strategy for efficient Li compensation for Li-ion batteries, which can significantly improve their energy density and increase their energy conversion efficiency and cycle life.