AUTHOR=Su Yuefeng , Chen Gang , Chen Lai , Li Linwei , Li Cong , Ding Rui , Liu Jiahui , Lv Zhao , Lu Yun , Bao Liying , Tan Guoqiang , Chen Shi , Wu Feng 

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

JOURNAL=Frontiers in Chemistry

VOLUME=8

YEAR=2020

URL=https://www.frontiersin.org/journals/chemistry/articles/10.3389/fchem.2020.00573

DOI=10.3389/fchem.2020.00573

ISSN=2296-2646

ABSTRACT=<p>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<sub>0.90</sub>Co<sub>0.06</sub>Mn<sub>0.04</sub>O<sub>2</sub> material surface, <italic>via</italic> 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.</p>