LiCoO2-catalyzed electrochemical oxidation of Li2CO3

Abstract

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.