Lactam derivatives as solid electrolyte interphase forming additives for a graphite anode of lithium-ion batteries

• Published in: Journal of power sources Vol. 244; pp. 711 - 715
• Main Authors: Yoon, Sujin, Kim, Hyemi, Cho, Jeong-Ju, Han, Young-Kyu, Lee, Hochun
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Amsterdam Elsevier B.V 15.12.2013; Elsevier
• Subjects: Anodes; Applied sciences; Caprolactam; Density; Density function theory; Derivatives; Direct energy conversion and energy accumulation; Electrical engineering. Electrical power engineering; Electrical power engineering; Electrochemical conversion: primary and secondary batteries, fuel cells; Electrolytes additives; Exact sciences and technology; Graphite; Interphase; Li-ion batteries; Lithium-ion batteries; Materials; Reduction (electrolytic); Solid electrolyte interphase layers; Solid electrolytes; Caprolactam; Solid electrolyte interphase layers; Li-ion batteries; Density function theory; Electrolytes additives; Lithium ion batteries; Solid electrolyte interface; Anode; Solid electrolyte; Lactam; Theoretical study; Electrode electrolyte interface; Forming; Secondary cell; Electrode material; Additive; Graphite; Density functional method
• ISSN: 0378-7753; 1873-2755
• DOI: 10.1016/j.jpowsour.2012.11.115

N-substituted caprolactam (CL) derivatives are examined as novel solid electrolyte interphase (SEI)-forming additives for improving the cycle performance of LiCoO2/graphite lithium-ion batteries (LIBs). Our electrochemical experiments and density function calculations reveal that N-substitution of acetyl, methyl, and vinyl functional groups to ɛ-CL greatly affects the oxidation/reduction reactions of the CL additives. The cyclability of LiCoO2/graphite cells are in the following order: acetyl–CL > ɛ-CL > methyl-CL > no additive > vinyl-CL. The cycle performance of acetyl–CL is comparable to that of VC, currently the most widely used SEI-forming additive in LIBs. The excellent performance of acetyl–CL is ascribed to the electron withdrawing nature of the acetyl group, which enhances the anodic stability and facilitates the reduction reaction, leading to superior SEI formation at the graphite anode. ►Caprolactam (CL) compounds are investigated as novel SEI-forming additives for LiCoO2/graphite cells. ► The nature of the N-substituent greatly affects the oxidation/reduction reactions of the CL additives. ► Electron withdrawing acetyl group is responsible for high anodic stability and good cycle performance of acetyl-CL.