A comparative study on low-purity natural graphite with various metal oxide impurities as an anode active material for lithium ion batteries

A comparative study on low-purity natural graphite with various metal oxide impurities as an anode active material for lithium ion batteries

Low-purity natural graphite, which is used as an anode active material for lithium-ion batteries, contains various impurities. To investigate the effects of these impurities on the lithium ion battery system, various metal oxides such as Fe2O3, Al2O3, andSiO2 were mixed with high-purity natural graphite using a glycine nitrate process (GNP) or hydrothermal method. While thereare no significant changes in the physical or chemical structure due to the addition of metal oxide impurities, theelectrochemical performance was considerably improved. Both Fe2O3- and SiO2-natural graphite composites showed a largerfirst charge capacity and better capacity retention compared to the high-purity natural graphite (NG-R) due to the conversionreaction and formation of the solid electrolyte interface (SEI) film, respectively. Specifically, the 05-Fe sample showed a chargecapacity of 421.8 mAh/g at the first cycle, but a high irreversible capacity of 50.4 mAh/g due to the irreversible conversionreaction. Nevertheless, the 05-Fe sample exhibited a significantly higher capacity retention (95.9%) than NG-R (84.9%).

Low-purity natural graphite, which is used as an anode active material for lithium-ion batteries, contains various impurities. To investigate the effects of these impurities on the lithium ion battery system, various metal oxides such as Fe2O3, Al2O3, andSiO2 were mixed with high-purity natural graphite using a glycine nitrate process (GNP) or hydrothermal method. While thereare no significant changes in the physical or chemical structure due to the addition of metal oxide impurities, theelectrochemical performance was considerably improved. Both Fe2O3- and SiO2-natural graphite composites showed a largerfirst charge capacity and better capacity retention compared to the high-purity natural graphite (NG-R) due to the conversionreaction and formation of the solid electrolyte interface (SEI) film, respectively. Specifically, the 05-Fe sample showed a chargecapacity of 421.8 mAh/g at the first cycle, but a high irreversible capacity of 50.4 mAh/g due to the irreversible conversionreaction. Nevertheless, the 05-Fe sample exhibited a significantly higher capacity retention (95.9%) than NG-R (84.9%).