High-performance lithium ion batteries using SiO2-coated LiNi0.5Co0.2Mn0.3O2 microspheres as cathodes

LiNi0.5Co0.2Mn0.3O2 (NCM 523) is one of the commercialized NCM cathode materials for lithium ion batteries. In this work, we demonstrate that a 0.5 wt% SiO2 nanoparticles-coated NCM 523 shows an improved cycling performance and thermal stability, compared with the pure NCM 523. The structural integrity of the NCM 523 during cycling processes can be maintained by the SiO2 coating layer with a thickness of about 20-30 nm. The 0.5 wt% SiO2-coated NCM 523 cathode exhibits a capacity retention of 82.5% over 100 cycles at 0.1 C between 2.5 and 4.3 V, while that of the pristine material is only 68%. Also, the 0.5 wt% SiO2-coated sample exhibits a higher reversible capacity (153.4 mAh g−1) and better capacity retention (92.4%) over 50 cycles than those of the pure NCM 523 (114.3 mAh g−1, 66.0%) in the electrolyte with lithium difluoro (oxalato)borate at 1 C in the voltage range of 2.8-4.5 V. The SiO2 coating layer plays a critical role in improving the electrochemical performance of NCM 523 cathode.