Effect of cyano dipolar groups on the performance of lithium-ion battery electrospun polyimide gel electrolyte membranes

Abstract

Effect of cyano dipolar groups on the performance of lithium-ion battery electrospun polyimide gel electrolyte membranes AbstractThree polyimide membranes (polymer 0CN, copolymers 0CN/2CN (50/50) and polymer 2CN), with and without [Formula presented] dipolar groups, have been prepared by electrospinning and evaluated as lithiumion battery separators. The prepared membranes show average fiber diameters between 0.5 and 1.09 μm and a degree of porosity of ~ 80%. The thermal stability, uptake, tortuosity and ionic conductivity values are influenced by the presence of the [Formula presented] dipolar groups in the polyimide polymer chain. The best battery performance in LFP/Li system is obtained for the 0CN sample, which shows discharge capacity values of 149.7 mAh·g− 1, 146.5 mAh·g− 1 and 124.6 mAh·g− 1 at C/20, C/10 and C/5, respectively. The obtained high solution uptake, ionic conductivity values and rate capability show that these materials are promising candidates for battery separators for rechargeable lithium-ion batteries, when compared to glass microfiber separators. The best battery performance in LFP/Li system is obtained for the 0CN sample, which shows discharge capacity values of 149.7 mAh.g -1 , 146.5 mAh.g -1 and 124.6 mAh.g -1 at C/20, C/10 and C/5, respectively. The obtained high solution uptake, ionic conductivity values and rate capability show that these materials are promising candidates for battery separators for rechargeable lithium-ion batteries, when compared to glass microfibre separators.

Strategic Structural Design of a Gel Polymer Electrolyte toward a High Efficiency Lithium-Ion Battery

“…Further investigation found that the high ionic conductivity could be associated with the good affinity of PI 11a, which holds liquid electrolyte via coordination through electrostatic interactions; thus, it results in higher electrolyte retention and uptake. 148 Maceiras et al 149 reported the copolymerization of two aromatic diamines, 1,3bis-2-cyano-3-(3-aminophenoxy)phenoxybenzene (diamine 2CN) and 1,3-bis(3-aminophenoxy)benzene (diamine 0CN) with 4,4′-oxidiphtalic anhydride (ODPA) to synthesize a new amorphous PI 11b for elucidating the effect of the cyano group (-CN) on the electrochemical performance of GPEs. 149 The resulting PI 11b was further prepared as a fiber using electrospinning process by dissolving in N,N-dimethylformamide and DMAc (1:1, v/v).…”

“…148 Maceiras et al 149 reported the copolymerization of two aromatic diamines, 1,3bis-2-cyano-3-(3-aminophenoxy)phenoxybenzene (diamine 2CN) and 1,3-bis(3-aminophenoxy)benzene (diamine 0CN) with 4,4′-oxidiphtalic anhydride (ODPA) to synthesize a new amorphous PI 11b for elucidating the effect of the cyano group (-CN) on the electrochemical performance of GPEs. 149 The resulting PI 11b was further prepared as a fiber using electrospinning process by dissolving in N,N-dimethylformamide and DMAc (1:1, v/v). After being activated by immersion into 1 M LiPF 6 in EC/DMC (1:1, v/v), the resulting GPE exhibited an ionic conductivity of 0.7 × 10 −3 S cm −1 at room temperature and a higher degree of porosity up to ∼80%.…”

“…The study revealed that the ionic conductivity values are influenced by the presence of -CN dipolar groups in PI 11b; however, the specific mechanism was not explained clearly in this study. 149 Poly(ether imide) (PEI) 11c is expected to also have good affinity between the skeleton materials and the polar liquid electrolyte due to the existence of ether bonds and amide bonds as well as the similar structure and polarity with PI. 150 Recently, a GPE composite based on 11c and halloysite nanotubes (HNTs) as fabricated by electrospinning technology.…”

Synthetic polymer-based membranes for lithium-ion batteries

“…In addition to these polymers, other synthetic polymers such as polyimide (PI) [40], poly (ether ether ketone) (PEEK) [41], polyetherimide (PEI) [42], polybenzimidazole (PBI) [43] and poly (m-phenylene) isophthalamide) (PMIA) [44] have been used to increase the thermal stability of the separator membranes, among other relevant parameters.…”

Synthesis and properties of the novel polyimides containing cyano and biphenyl moieties

“…It is well known that polar cyano groups (–CN) have large dipole moment and polarizability; thus, they can form stable complex through hydrogen bonds and strong intermolecular forces. 14 –17 In addition, the cyano-containing polymers usually have strong interaction with the matrix, when they work as coating materials. 18 It is of interest to introduce the –CN groups into high-performance polymers to enhance their adhesive strength and other properties, especially when they used as functional coatings and multilayer films.…”