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Highly Efficient Multicomponent Gel Biopolymer Binder Enables Ultrafast Cycling and Applicability in Diverse Battery Formats

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journal contribution
posted on 17.11.2020, 19:41 authored by Ling Ding, Rita Leones, Ahmad Omar, Jing Guo, Qiongqiong Lu, Steffen Oswald, Kornelius Nielsch, Lars Giebeler, Daria Mikhailova
Electrode materials with a high performance and stable cycling have been commercialized, but the utilization of state-of-the-art Li-ion batteries in high-current rate applications is restricted because of limitations in other battery components, in particular, the lack of an efficient binder. Herein, a novel multicomponent polymer gel binder (PGB) is presented, comprising the biopolymer chitosan as the host, embedded with the 1-butyl-1-methylpyrrolidinium dicyanamide (PYR14DCA) ionic liquid and the lithium bis­(trifluoromethanesulfonyl)­imide (LiTFSI) salt. The multicomponent approach leads to carbon black arrangement along well-distributed chitosan chains in the electrodes, forming a highly electronic conductive network. Furthermore, the plasticizing effect of the ionic liquid leads to an enhanced ionic conductivity. As a result, shorter charge-transfer paths are enabled, leading to an exceptionally high rate capability in LiFePO4 and Li4Ti5O12 half cells, up to 50C. LiFePO4||Li4Ti5O12 full cells using the PGB for both electrodes also demonstrated stable cycling at 10C, with an impressively high discharge capacity of 173 mA h·g–1 after 1000 cycles. In addition, freestanding electrodes could also be realized and functioning flexible Li-ion cells were successfully demonstrated. Thus, the novel water-processable binder offers multifaceted advantages, making the approach highly promising for industrial implementation.