Improved cycle performance of Li[Li0.2Mn0.54Co0.13Ni0.13]O2 by Ga doping for lithium ion battery cathode material

Lithium-excess layered cathode materials Li[Li0.2Mn0.54Co0.13Ni0.13 − xGax]O2 (x = 0, 0.01, 0.02, 0.04) with different quantities of Ga were synthesized by the coprecipitation-calcination method. Substituted Li-rich cathode material Li[Li0.2Mn0.54Co0.13Ni0.13 − xGax]O2 by Ga (as reflected by their stoichiometry ratio) results in a decrease of their specific capacity at the first few cycles, as expected, but its structure stability is improved upon cycling dramatically. XPS study verified that Ga3 + doping strengthens the MO bond energy, decrease the loss of oxygen to stabilize the reversible anionic redox processes (O2-/O22- or O2-/O2n-, where 3 > n > 1). Li[Li0.2Mn0.54Co0.13Ni0.11Ga0.02]O2 electrode exhibits a discharge specific capacity of 229.4 mAh g− 1 after 100 cycles at 0.1 C and the capacity retention ratio is 88.2% while only 195.5 mAh g− 1 and 68.8% are obtained for the pristine electrode. In addition, the Ga-doped electrode Li[Li0.2Mn0.54Co0.13Ni0.11Ga0.02]O2 has a slight positive effect on rate property, whose discharge specific capacity is 155.5 mAh g− 1 at 5C compared to the pristine (145.9 mAh g− 1). From the Nyquist plots, it can be deduced that the Ga doping improves the interfacial electrochemical reaction activity between the electrode and electrolyte.