Improved electrochemical performance of LiNi0.8Co0.1Mn0.1O2 cathode material for Lithium-ion batteries by using pre-oxidation of K2Cr2O7

• The electrochemical properties of LiNi 0.8 Co 0.1 Mn 0.1 O 2 has been improved by K 2 Cr 2 O 7 . • The sample with 1% K 2 Cr 2 O 7 content has the best performance. • The reason is attributed to the formation of more ordered layered structures on the surface. The precursor was pre-oxidized with K 2 Cr 2 O 7 as oxidant, and Ni 2+ on the surface was immediately oxidized to Ni 3+ , resulting in a more ordered surface structure of the precursor. It was found by XRD and SEM that the precursor pre-oxidation did not produce new phase, the surface morphology of the synthesized material did not change obviously, and the degree of cation confusion was reduced. After K 2 Cr 2 O 7 pre-oxidation of the precursor, the electrochemical properties of the samples were greatly improved. In particular, the sample with 1% K 2 Cr 2 O 7 content had the best performance. After 50 cycles at 1 C and 3-4.3 V, the capacity can still retain 177.7 mAh g -1 , and the capacity retention rate was as high as 99.1%. After 50 cycles, the capacity was only 161.6 mAh g -1 , and the capacity retention rate was 96.6%. When charged to a high voltage of 4.5 V, the NCM-1 can derive a discharge capacity of 200.9 mAh g -1 , which retained 173.2 mAh g -1 after 50 cycles, while the pristine had 165 mAh g -1 after 50 cycles. There was also a decrease in Ni 2+ content, which reduced the degree of cation confusion and increased the kinetics of charge transfer and lithium ion diffusion.