The Origin of the residual carbon in lifepo₄ synthesized by wet milling

This study reports the origin of the electrochemical improvement of LiFePO₄ when synthesized by wet milling using acetone without conventional carbon coating. The wet milled LiFePO₄delivers 149 mAhg^-1 at 0.1 C, which is comparable to carbon coated LiFePO ₄and approximately 74% higher than that of dry milled LiFePO ₄, suggesting that the wet milling process can increase the capacity in addition to conventional carbon coating methods. UV spectroscopy, elemental microanalysis, and evolved gas analysis are used to find the root cause of the capacity improvement during the mechanochemical reaction in acetone. The analytical results show that the improvement is attributed to the conductive residual carbon on the surface of the wet milled LiFePO₄particles, which is produced by the reaction of FeC₂O₄. 2H ₂O with acetone during wet milling through oxygen deficiency in theprecursor.