F-doping effects on microstructure and electrochemical performance of cathode material Li_(1.2)Mn_(0.54)Ni_(0.13)Co_(0.13)O_(2)

Lithium-rich manganese-based(Li-rich Mn-based)cathode materials possess high specific capacity,low self-discharge rate and steady working voltage,but cycle performance and rate performance need to be further improved.In this study,cathode materials Li_(1.2)Mn_(0.54)Ni_(0.13)Co_(0.13)O_(2-x)F_(x)(x=0,0.02,0.05,0.08)are synthesized by the co-precipitation method with the two-step calcination process.And the F-doping effects on the microstructure and the electrochemical performance are investigated in the cathode materials Li_(1.2)Mn_(0.54)Ni_(0.13)Co_(0.13)O_(2).The results indicate that among all the F-doped cathode materials,the crystal lattice parameters are increased,order degree and stability of the layered structure are improved.As for x=0.05,cathode material Li_(1.2)Mn_(0.54)Ni_(0.13)Co_(0.13)O_(1.95)F_(0.05)(LMO-F_(0.05))shows the best cycle performance and rate performance with its capacity retention rate 87.7%after 100 cycles at 0.2 C and discharge capacity 117 mAh g−1 at 5 C high power.It can be seen that F doping is a simple and crucial strategy to promote the Li ion diffusion and develop high performance layered cathode materials.