Clean the Ni-Rich Cathode Material Surface With Boric Acid to Improve Its Storage Performance

Abstract

The existence of residual lithium compounds (RLCs) on the surface of layered Ni-rich materials will deteriorate the electrochemical properties and cause safety problem. This work presents an effective surface washing method to remove the RLCs from LiNi 0.90 Co 0.06 Mn 0.04 O 2 material surface, via ethyl alcohol solution that contains low concentration of boric acid. It is a low-cost process because the filter liquor can be recycled. The optimal parameters including washing time, boric acid concentration, and solid-liquid ratio were systematically studied. It has been determined by powder pH and Fourier transform infrared spectra results that the amount of RLCs was reduced effectively, and the storage performance was significantly enhanced for the washed samples. The 150th capacity retentions after storing had increased from 68.39% of pristine material to 85.46-94.84% of the washed materials. The performance enhancements should be ascribed to the surface washing process, which removed not only the RLCs, but also the loose primary particles effectively.

Key Parameter Optimization for the Continuous Synthesis of Ni-Rich Ni–Co–Al Cathode Materials for Lithium-Ion Batteries

“…In addition, the c/a ratio value of NCA-107 is larger than 4.9, indicating its well-ordered layered structure . Due to optimal calcination temperature, three cathodes all show a spherical morphology with the smooth particle surface without raised dendrite gains (Figure d–f), which is in good agreement with other Ni–Co–Al materials reported. , The detailed microstructure was further investigated by HRTEM. The clear lattice fringes assigned to the 003 plane confirm a typical layered structure of the NCA-107 cathode (Figure g,h and Figure S5).…”

A Review of Degradation Mechanisms and Recent Achievements for Ni‐Rich Cathode‐Based Li‐Ion Batteries

“…That will likely lead to the formation of undesirable RLCs layers. [ 30 ] The highly active Ni 3+ ions in the cathode material can contribute to the RLCs formation as well. The spontaneous reduction of Ni 3+ to Ni 2+ at the surface will give rise to lattice oxygen O 2− oxidation and the consequent reaction with Li + .…”

“…Appropriate water‐washing or acid‐washing processes can dramatically eliminate the side effects of RLCs. [ 30 ] However, to fight cation disorder and crystallographic defects, more advanced synthesis methods have to be applied.…”

On the role of surface carbonate species in determining the cycling performance of all-solid-state batteries

“…It should be noted though that a recent review article by Schürmann et al is questioning the electrochemical generation of 1 O 2 [18]. Regardless, for the application of Ni-rich NCM-type CAMs in high-performance LIBs, washing for the removal of residual lithium (followed by drying or post-annealing), without adversely affecting the lithium inventory and surface structure, is frequently required [12,[19][20][21][22][23][24][25].…”