Improving the electrochemistry performance of layer LiNi0.5Mn0.3Co0.2O2 material at 4.5 V cutoff potential using lithium metaborate

LiNi0.5Mn0.3Co0.2O2 (NMC) cathode material is surface treated by Li active boron oxide (LBO) via a two-step process. The surface morphology, crystal structure, surface composition, and electrochemical properties were characterized based on SEM, XRD, XPS, charge-discharge tests, cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS) measurements. XPS results showed that the coating layer was composed of LiBO2. The 2 wt% LBO-coated NMC exhibited the best electrochemical performance at high voltage (4.5 V). It was achieved a high capacity retention of 91.23% after 50 cycle which was 53.19% for the uncoated one. The rate capability of the coated electrode was improved obviously, exhibiting 114.71 mAh.g(-1) discharge capacity at 10 C. The interfacial resistance and charge transfer resistance was also decreased owning to the fact that the coating layer played a firewall between the electrolyte and the NMC electrode. (C) 2017 Elsevier Ltd. All rights reserved.