Enhanced Cycling and Structure Stability of an Electron Transfer-Accelerating Polymer Poly(3,4-ethylenedioxythiophene):Poly(styrenesulfonate)-Covered Mn-Based Layered Cathode with Ga3+ Doping for a Li-Ion Battery

Mn-based cathode material Li1.20Mn0.52Ni0.20Co0.08O2 was proposed and ameliorated by surface-coating poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) and doping Ga3+. X-ray diffraction and high-resolution transmission electron microscopy studies revealed that part of Ga3+ replacing the Ni site could reduce the Li+/Ni2+ mixing by forming a well-ordered layered structure and a homogeneous coating layer of PEDOT:PSS is covered on the surface of Li1.20Mn0.52Ni0.19Co0.08Ga0.01O2. The results of the electrochemical studies demonstrated the higher initial charging–discharging Coulombic efficiency, and outstanding rate capabilities and cyclic performance were obtained for the PEDOT:PSS-covered and Ga3+-doped samples. Especially, 2 wt % PEDOT:PSS-coated Li1.20Mn0.52Ni0.19Co0.08Ga0.01O2 delivered 38.3 mAh g–1, which is larger than the pristine cathode at a 5C high rate. Meanwhile, it could retain 189.6 mAh g–1 (90.3% of its initial discharge capacity at 45 °C) after 300 cycles with a 1C rate, while the pristine cathode only delivered 149.7 mAh g–1 with 80.7% cycling retention left. The results strongly suggested that such PEDOT:PSS-coated and Ga3+-doped Mn-based layered structure materials demonstrated high potential as a cathode candidate especially for high-energy applications.