Improving the rate performance of manganese dioxide by doping with Cu 2+ Co 2+ and Ni 2+ ions

Abstract

Metal-doped MnO 2 has been successfully synthesized via chemical precipitation method. Interestingly, doping can increase not only ion conductivity but also intrinsic electron conductivity. By doping, the particle size of MnO 2 decreases, relatively appropriate pore size distribution is obtained, and physically and chemically bound water content increases, all of which contribute to ion conductivity. Meanwhile, doping has induced some defects in MnO 2 crystal, increasing the hole concentration and then intrinsic electron conductivity. As the result, metal-doped MnO 2 displays better rate performance than the un-doped. Especially, nickel-doped MnO 2 exhibits the best rate behavior. Even at 8 A g -1 , nickel-doped MnO 2 still has a specific capacitance as high as 234.0 F g -1 , larger than that of the un-doped obtained at 1 A g -1 (only 173.6 F g -1 ). In conclusion, doping is a useful way for improving the rate performance of MnO 2 .