Cross-Linked Polyacrylonitrile-Based Elastomer Used as Gel Polymer Electrolyte in Li-Ion Battery

Abstract

Gel polymer electrolytes (GPEs) based on polyacrylonitrile elastomer (HNBR) are investigated for lithium-ion batteries application. This study examines the acrylonitrile content, as well as the solvent used to make the GPE, to understand their impact on lithium solvation. To do so, we propose a three-component system comprising HNBR:solvent:LiTFSI to pinpoint the correct ratio to provide the GPE with competitive conductivity. Infrared spectroscopy is used to shed light on the interactions between nitriles and lithium ions. Spin–lattice relaxation times (T 1) and diffusion coefficients of 7Li and 19F for various HNBR-based GPEs are obtained through PFG-NMR, enabling determination of the transport number of lithium cations (t +) and activation energy (E a). Among the GPEs tested, those composed of propylene carbonate with 2 M LiTFSI and HNBR with an acrylonitrile content of 50% are the most promising, with an ionic conductivity of 2.1 × 10–3 S/cm, D 7Li of 12.0 × 10–8 cm/s, and a t + of 0.42 at room temperature. When this GPE was tested in Li5Ti4O12/LiFePO4 coin cells, a capacity of 135 mAh/g was obtained at a discharge rate of D/5, showing promising results for its use in Li-ion batteries. This study highlights the benefits of high acrylonitrile content in the polymer and a solvent with a moderate donor number to promote interactions between nitriles and Li+.

The Impact of Absorbed Solvent on the Performance of Solid Polymer Electrolytes for Use in Solid-State Lithium Batteries

“… Verdier et al. (2020) compared the lithium-ion solubilizing ability of PC with that of DMC and DMSO in hydrogenated butadiene rubber (HNBR)-based gel electrolyte.…”

“…This study used IR spectroscopy to monitor the intensity of the peak at 2261 cm −1 , attributable to the interaction between nitrile groups and lithium ions, as a function of the concentration LiTFSI in the gel electrolyte ( Wang et al., 1996 ; Verdier et al., 2020 ). In the sample containing PC, the peak at 2264 cm −1 was observed at LiTFSI concentrations between 0.5 and 2 M ( Figure 6 ) ( Verdier et al., 2020 ). In the sample containing DMC, this peak was observed at LiTFSI concentrations between 10 −3 and 2 M, whereas no interaction between lithium ions and the nitrile groups was observed in the sample that was swelled with DMSO ( Verdier et al., 2020 ).…”

Advanced Characterization Techniques for Interface in All‐Solid‐State Batteries

“…By collecting the NMR signal, we can analyze the chemical information of the sample. Various nuclear magnetic resonance technologies have been developed to explore the dynamic processes and chemical structures for the electrode materials, such as magic angle spinning (MAS) NMR, [ 76 ] pulsed‐field gradient (PFG) NMR, [ 77 ] 2D exchange spectroscopy (2D EXSY) NMR and magnetic resonance imaging (MRI). [ 78 ] MAS NMR is considered as the best solution for solid‐state NMR as it greatly enhances the resolution of solid‐state NMR, which is widely used to characterize the local structure of materials and electrochemical mesophase products.…”

Advances in Natural Biopolymer‐Based Electrolytes and Separators for Battery Applications

“…While polyether, [ 17 ] polysulfone, [ 18 ] polysiloxane, [ 19 ] and polyborate, [ 20 ] based homopolymers and copolymers have been explored as matrix for SPEs and backbone for single‐metal ion conductors (defined by an unity metal ion transference number), polyethylene oxide (PEO), [ 21 ] poly(methyl methacrylate) (PMMA), [ 22 ] polyacrylonitrile (PAN), [ 23 ] polyvinyl acetate (PVAc), [ 24 ] and polyvinylidene fluoride (PVDF), [ 25 ] have been the focus of GPE development. Most of these synthetic polymers are either fossil fuel derived, [ 26 ] or non‐biodegradable.…”

“…The electrolyte plays the critical role of shuttling the mobile ionic species between the two electrodes (positive and negative) and thereby balances the flow of electrons in the outer circuit number), polyethylene oxide (PEO), [21] poly(methyl methacrylate) (PMMA), [22] polyacrylonitrile (PAN), [23] polyvinyl acetate (PVAc), [24] and polyvinylidene fluoride (PVDF), [25] have been the focus of GPE development. Most of these synthetic polymers are either fossil fuel derived, [26] or non-biodegradable.…”