Enhanced Cycling and Structure Stability of an Electron Transfer-Accelerating Polymer...

Mn-based cathode material Li_1.20Mn_0.52Ni_0.20Co_0.08O₂ 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 Li_1.20Mn_0.52Ni_0.19Co_0.08Ga_0.01O₂. 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 Li_1.20Mn_0.52Ni_0.19Co_0.08Ga_0.01O₂ 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.