Tuning the surface chemistry of natural graphite anode by H3PO4 and H3BO3 treatments for improving electrochemical and thermal properties

We introduce an effective way to improve the electrochemical and thermal stabilities of natural graphite anodes of lithium ion batteries. Through a thermal decomposition of H3PO4 and H3BO3, phosphorus and boron can be successfully incorporated into the surface of natural graphite by the formation of chemical bonds with carbon. By incorporation of these heteroatoms, the electrochemical stability of natural graphite can be significantly improved, even under severe operating conditions. From the results of various structural and electrochemical analyses, the incorporated heteroatoms are thought to be affecting the physicochemical properties of the solid electrolyte interphase (SEI) by promoting additional Li+ consumption and thus making it more stable. In addition, we found that the heteroatoms also have potential to improve the thermal resistivity of the natural graphite anode. These findings could be helpful for developing natural graphite anodes with a good electrochemical as well as thermal properties for use in lithium ion batteries.