Organic skin layer with carboxyl and electron-withdrawing nitro groups to chemically bind with residual Li and Ni cations on single-crystal LiNi0.8Co0.1Mn0.1O2. (1st February 2022)

• Record Type: Journal Article
• Authors: Long, Fu; Cao, Zhang; Liu, Yuyang; Liang, Rui; Qu, Qunting; Lv, Linze; Jin, Chengchang; Zheng, Honghe
• Is Part Of: Electrochimica acta. Volume 404(2022)
• Publication Date: 2022-02-01
• Subjects: LiNi0.8Co0.1Mn0.1O2 cathode -- Surface layer -- Cathode electrolyte interphase -- 4-Nitrobenzoic acid -- Lithium ion batteries; Electrochemistry -- Periodicals; Electrochemistry, Industrial -- Periodicals; 541.37
• DOI: 10.1016/j.electacta.2021.139743
• Languages: English
• ISSNs: 0013-4686

Abstract

Highlights: 4-Nitrobenzoic acid (4-NBA) is grafted onto the surface of singe-crystal NCM811. The carboxyl groups of 4-NBA neutralize the residual lithium compounds of NCM811. A cathode/electrolyte interphase with low impedance is obtained. The electron-withdrawing nitro groups of 4-NBA inhibit Ni dissolution. This surface grafting technique improves the electrochemical performance of NCM811. Abstract: Interfacial issue is very critical to the electrochemical properties of LiNi0.8 Co0.1 Mn0.1 O2 (NCM811) cathode, and it also poses a great challenge for successful commercialization of NCM811 via construction of a desirable surface layer. This work constructs a novel metal-organic interface by grafting organic 4-NBA (4-nitrobenzoic acid) layer onto singe-crystal NCM811 surface. The electron transfer from the interfacial Ni 2+ to the electron-withdrawing nitro group of 4-NBA promotes the formation of metal-organic interface, which inhibits Ni dissolution into the organic electrolyte. The neutralization reaction between the carboxyl groups of 4-NBA and residual lithium compounds of NCM811 constructs an interfacial layer with improved Li + conductivity. The 4-NBA organic layer also helps constructing a thin and stable cathode/electrolyte interphase by alleviating the side reactions of electrolyte. The electrochemical properties of single-crystal NCM811 cathode are remarkably enhanced. At a high discharge rate of 20C, a capacity of 141 mAh g −1 can be delivered, significantly higher than that of 101 mAh g −1 of the pristine cathode. After 200 cycles at 1C, the modified sample exhibits excellent capacity retention of 84.5%. Graphical abstract: Image, graphical abstract