Allylimidazolium-Based Poly(ionic liquid) Anodic Binder for Lithium-Ion Batteries with Enhanced Cyclability

Abstract

An allylimidazolium-based poly(ionic liquid), poly-[vinylbenzylallylimidazolium bis(trifluoromethane)sulfonylimide] (PVBCAImTFSI) was used as a binder for graphite anodes in lithium-ion batteries. The anodes with the synthesized binder exhibited lesser electrolyte degradation and higher lithium-ion diffusion. Electrochemical impedance spectroscopy (EIS) results showed decreased interfacial and diffusion resistance for PVBCAImTFSI-based electrodes after cycling compared to PVDF-based anodes. Dynamic electrochemical impedance spectroscopy (DEIS) results indicated the interfacial resistance of the interface formed for the PVBCAImTFSI-based anodes to be 3 times lesser than the PVDF-based anodes. Suppression of electrolyte degradation and decrease in the intercalation− deintercalation potential and improved Li-ion diffusion coefficient for PVBCAImTFSI-based half-cells were observed from cyclic voltammetry measurements. DFT-based theoretical studies also speculated the suppression in the electrolyte degradation in the case of PVBCAImTFSI binder due to the positioning of its HOMO−LUMO levels. A reversible discharge capacity of 210 mAh/g was obtained for PVBCAImTFSI-based half-cells at 1C rate as compared to the 140 mAh/g obtained for PVDF-based anodic half-cells. After 500 cycles, 95% retention in the discharge capacity was observed. Also, PVBCAImTFSI-based anodes exhibited better charge− discharge stability than the PVDF-based anodes. Suppression of electrolyte degradation, reduction in the interfacial resistance, enhanced wettability, and an optimal SEI layer formed in the case of PVBCAImTFSI-based anodes cumulatively led to an enhanced stability and cyclability during the charge−discharge studies as compared to the commercially employed PVDF-based anodes. Thus, the tuning of the interfacial properties leads to the improvement in the performance of the lithium-ion batteries with PVBCAImTFSI as a binder.

Zinc blende inspired rational design of a β-SiC based resilient anode material for lithium-ion batteries

“…The deconvoluted core HRXPS of the C 1s spectrum comprises six peaks and can be assigned to the contribution from SiC ($283.6 eV), characteristic -C]C-($284.6 eV), C-O ($286.1 eV), C-F ($288.2 eV), Li 2 CO 3 ($288.8 eV) and alkyl carbonate (289.6 eV). 45,47,[60][61][62] Similarly, the Li 1s peak comprises four peaks (Fig. 11b) namely Li 2 O ($54 eV), alkyl carbonate (R-OCO 2 Li $ 54.6 eV), Li 2 CO 3 ($55.1 eV) and LiF (55.7 eV).…”

“…11b) namely Li 2 O ($54 eV), alkyl carbonate (R-OCO 2 Li $ 54.6 eV), Li 2 CO 3 ($55.1 eV) and LiF (55.7 eV). 53,54,[60][61][62] The F 1s spectrum (Fig. 11c) indicates the presence of four constituent peaks attributed to the NaF ($684 eV), LiF ($684.8 eV), Li x PF y ($686.4 eV) and -C-F-($687.5 eV).…”

“…11c) indicates the presence of four constituent peaks attributed to the NaF ($684 eV), LiF ($684.8 eV), Li x PF y ($686.4 eV) and -C-F-($687.5 eV). 53,54,56,[60][61][62] These various carbon, uorine and lithium-based observed moieties are the common features of the SEI in post cycled anodes. 61,62 In the present study, sodium comes from the binder which is in the form of sodium carboxymethyl cellulose.…”

“…53,54,56,[60][61][62] These various carbon, uorine and lithium-based observed moieties are the common features of the SEI in post cycled anodes. 61,62 In the present study, sodium comes from the binder which is in the form of sodium carboxymethyl cellulose. The deconvolution of the Si 2p peak shows the presence of SiC ($100.9 eV) as a main peak and a small auxiliary SiC x O y ($102 eV) contribution.…”

Impact of Binder Functional Groups on Controlling Chemical Reactions to Improve Stability of Rechargeable Zinc-Ion Batteries

“…If carefully chosen, the binder can help mitigate the abovementioned problems in the ZIB cathode at a lower cost. In Li batteries, binder selection has been shown to play an important role in improving the stability of electrodes and enhancing battery performance. − However, the role of binders in ZIBs has not been comprehensively investigated to date, and little research has been carried out in this area.…”