Polypyrrole-coated Mn-Fe bimetallic oxides as high stability anode for lithium-ion batteries

摘要

Transition metal oxides as anode materials have received extensive research owing to the high specific capacity. However, the rapid decline of battery capacity caused by volume expansion and low electrical conductivity hinders the practical application of transition metal oxides. This study reported a pseudo-capacitance material polypyrrole-coated Fe_2O_3/Mn_2O_3 composites material as a high stability anode for lithium-ion batteries. The polypyrrole coating layer can not only serve as a conductive network to improve electrode conductivity but also can be used as a protective buffer layer to suppress the volume change of Fe_2O_3/Mn_2O_3 during the charging and discharging process. At the same time, the porous structure of Fe_2O_3/Mn_2O_3 composite can not only provide more active sites for lithium storage but also play a certain buffer effect on the volume change of the material. Polypyrrole-coated Fe_2O_3/Mn_2O_3 composite as the anode for lithium-ion batteries shows great electrochemical storage performance, with high specific capacity (627 mAh g~(-1) at a current density of 1 A g~(-1)), great cycle stability (the capacity not shows obvious signs of attenuation after 500 cycles), and rate performance (432 mAh g~(-1) at a current density of 2.0 A g~(-1)).