Improving Electrochemical Cycling Stability of Ni‐rich LiNi_0.91Co_0.06Al_0.03O₂ Cathode Materials through H₃BO₃ and Y₂O₃ Composite Coating

Abstract

The nickel-rich LiNi 0.91 Co 0.06 Al 0.03 O 2 cathode material has attracted wide attention due to its high energy density and appropriate thermal stability; however, its practical application has been greatly restricted by exorbitant residual LiOH/Li 2 CO 3 and poor cycling performance. In this work, we have reduced the residual LiOH/Li 2 CO 3 by washing the LiNi 0.91 Co 0.06 Al 0.03 O 2 fabricated through a high-temperature solid-state method and improved the cycling performance with a composite coating process. The results show that the amount of residual LiOH/ Li 2 CO 3 in the washed materials is significantly decreased, which is very favorable for the processability of materials. Li-Ni 0.91 Co 0.06 Al 0.03 O 2 with 0.1 wt% composite coating exhibits optimum properties: the discharge capacity reaches 217.4 mAh/ g at 0.1 C, the cycling retention still remains at 93.7 % after 100 cycles at 1 C, and the cycling retention of the soft-packing battery remains as high as 81.7 % after 800 cycles at 1 C. The excellent electrochemical performances are attributed to the synergistic effect of excellent fluidity of H 3 BO 3 and outstanding stability of Y 2 O 3 , mitigating the interface reaction between electrolyte and cathode material.

Recent progress in synthesis and surface modification of nickel-rich layered oxide cathode materials for lithium-ion batteries

“…In a full cell with Si/C-400 as an anode, capacity retention of 85% was maintained after 1000 cycles at 100 mA g −1 even under −20 • C. The suppression of the microcrack evolution and phase transition (figure 12(B)) and enhanced ion conduction upon the LBO encapsulation accounted for the satisfactory rate capability of the modified cathode. The cycling stability of LiNi 0.91 Co 0.06 Al 0.03 O 2 was improved via the synergistic effect of excellent fluidity of H 3 BO 3 and the outstanding stability of Y 2 O 3 (NCA-BY0.1) [314]. Benefiting from the interface reaction being mitigated, NCA-BY0.1 showed a capacity retention of 93.7% at 1 • C over 100 deep charge-discharge cycles, which was much better than bare NCA (91.6%).…”