Ultrathin Al2O3 Coatings for Improved Cycling Performance and Thermal Stability of LiNi0.5Co0.2Mn0.3O2 Cathode Material
Abstract Ultrathin Al 2 O 3 is directly deposited on LiNi 0.5 Co 0.2 Mn 0.3 O 2 (NCM523) composite electrodes by atomic layer deposition (ALD) After 4 ALD cycles, the coated cathode exhibits significantly improved cycling performance and thermal stability, especially at high working voltage. The capacity retention of the coated cathode is 76.8% after 30 cycles in the voltage range of 2 4.8 V, compared to 58.4% of pristine cathode. The exothermic peak in differential scanning calorimetry (DSC) analysis, corresponding to the reactions between delithiated electrode and electrolyte, is also delayed after cycling. The improvement is attributed to the reduced charge transfer resistance and enhanced Li ion diffusivity, as the Al 2 O 3 coating may suppress the side reactions between electrode and electrolyte, and inhibit the oxygen release under high operating voltage.