Electrochemical characterization of nano V, Ti doped MnO2 in primary lithium manganese dioxide batteries with high rate

摘要

The nano-sized gamma-MnO2 precursor is synthesized using a room temperature, liquid-phase reaction route with the assistance of ultrasonic waves. The MnO2 precursor as an electrode material in lithium manganese dioxide primary batteries displays a low capacity of 140mAh g(-1) (45.5% for the theoretical capacity of MnO2) at 20mA g(-1). Therefore, the doped MnO2 with cationic V or/and Ti are prepared at high temperature. After the heat treatment, the gamma phase precursor powder gradually converts into the beta-MnO2 and exhibits a higher specific surface area with a larger pore volume and pore size, providing significantly more electrochemically active sites for the redox reaction. The doped MnO2 matrix has advantage of the ideal lattice parameters and the higher conductivity, resulting in an enhancement of the Li+ diffusion kinetics in the tunnel structure. Especially for co-doped MnO2 with V and Ti, the modified material shows an outstanding electrochemical capacity of 190mAh g(-1) (61.7% for the theoretical capacity) at 20mA g(-1) and 169mAh g(-1) for a higher power output of 100mA g(-1).