Physically cross-linked polymer binder based on poly(acrylic acid) and ion-conducting poly(ethylene glycol-co-benzimidazole) for silicon anodes

• Published in: Journal of power sources 2017-08, Vol.360, p.585-592
• Main Authors: Lim, Sanghyun, Lee, Kukjoo, Shin, Inseop, Tron, Artur, Mun, Junyoung, Yim, Taeeun, Kim, Tae-Hyun
• Format: Article
• Language: English
• Subjects: High capacity; Ion conductivity; Physical crosslinking; Polymer binder; Silicon anode
• ISSN: 0378-7753; 1873-2755
• DOI: 10.1016/j.jpowsour.2017.06.049

The practical applications of Si electrodes in lithium-ion batteries are limited since they undergo large changes in volume during charge and discharge, and consequently become highly deteriorated. A novel binder system holding silicon particles together and preventing disintegration of the electrode during operation hence needs to be developed to enable reliable cycleability. In the current work, such a new polymer binder system, based on poly(acrylic acid) (PAA) and poly(ethylene glycol-co-benzimidazole) (PEGPBI), is developed for silicon anodes. The physical crosslinking using acid-base interactions between PAA and PBI, together with the ion-conducting PEG group, yields physical properties for the resulting PAA-PEGPBI-based anodes that are better than those of electrodes based on the currently available PAA binder, and yields good cell performances. A Si-based electrode with high loading levels of 1.0–1.3 mg cm−2 (0.7–0.91 Si mg cm−2) is reliably manufactured using specifically PAA-PEGPBI-2, which is made with 2 wt% of PEGPBI relative to PAA, and shows a very high capacity value of 1221 mAh g−1 at a rate of 0.5 C after 50 cycles, and a high capacity value of more than 1600 mAh g−1 at a high rate of 2 C. [Display omitted] •Physically-crosslinked polymer binders are developed for Si anode.•Physical and electrochemical properties of new binders are investigated.•Reversible acid-base interaction and ion conductivity are provided to new binders.