Investigation of the LiBH4 Modification Effect on Cycling Stability and High-Rate Capacity of LiCoO2 Cathodes

A LiCoO2 (LCO) cathode with LiBH4 modification (LBH-LCO) was obtained in a facile condition using a fast wet-chemical synthesis method. X-ray photon spectroscopy analysis indicates that B3+ in LiBH4 with high oxygen affinity can quickly incorporate onto the LCO surface accompanied by Co3+ reduction. Meanwhile, XRD characterization shows that the modified samples have a clear crystalline lamellar structure. After being modified by LiBH4, LBH-LCO present increased cycling stability [with near 95%/85% capacity retention at 1 C/5 C (1 C = 180 mA g–1) rates after 100/300 cycles] and better rate performance from 0.2 to 5 C under 4.6 V operation, compared to the pristine LiCoO2 (P-LCO). Electrochemical testing also shows that the LBH-LCO cathode retains a much higher Li+ chemical diffusion coefficient and smaller charge transfer impedance increases than the P-LCO. Even after being exposed to moist air for 48 h, the discharge capacity of the LBH-LCO can still reach 202 mA h g–1, which has a strong commercial application prospect.