Effects of Citric Acid Treatment on the Electrochemical Properties of Li1.2Mn0.54Ni0.13Co0.13O2 Cathode Material

The influence of citric acid pre-activation on the electrochemical properties of cathode materials used in lithium batteries is investigated. During the citric acid pre-activation of the surface of coprecipitated Li1.2Mn0.54Ni0.13Co0.13O2, 13.37 wt.% of lithium is removed, mainly owing to the decomposition of the Li2MnO3. Electrochemical property tests indicate that the cycle performance and rate capability of the material are enhanced after citric acid pre-activation. The initial charge-discharge efficiency increases from 66.4% to 79.9%, while the capacity retention after 100 cycles at 0.5C increases from 84.85% to 90.81%. When the current density increases to 5C, the specific discharge capacity of the delithiated material is 108.9 mAh.g(-1), much higher than that (95.10 mAh.g(-1)) before the treatment. This is caused by the formation of a spinel-like structure on the cathode surface, as citric acid removes some of the Li2O in the Li2MnO3 phase. As a result, a channel for Li+ transmission is created and the impedance at the interface between the cathode material and the electrolyte is effectively reduced, facilitating the rapid transport of Li+ through the electrode interface.