Synthesis and electrochemical behavior of K+ and Mn2+ co-doped LiFePO4/C as a cathode material for lithium-ion batteries and the mechanism of modification

•Mn and K co-doped LiFePO4 were synthesized by a rapid solvothermal method.•The contribution of doping elements is discussed in detail in conjunction with density functional theory (DFT).•A failure model for Mn dissolution was constructed to discuss the synergistic effect of double doping.•Mn and K co-doped LFP (KLMFP) exhibit excellent electrochemical properties.