UV-cured cross-linked polymer electrolytes are promising electrolytes for safe Li-ion batteries (LIBs) application due to their excellent conduction ability, low glass-transition temperature (T g ), and high discharge capacity. Herein, we have prepared novel fluorosulfonylimide methacrylic-based cross-linked polymer electrolyte membranes for LIBs via UV-curing process, which is a well-known, easy, low-cost, fast, and reliable technique. The synthesized UV-reactive novel methacrylate monomer with directly attached fluorosulfonylimide functional group methacryloylcarbamoyl sulfamoyl fluoride (MACSF) was used as a precursor for UV curing along with poly(ethylene glycol) dimethacrylate (PEGDMA) and lithium bis(fluorosulfonyl)imide (LiFSI). The results demonstrated that the cross-linked membrane with an optimized amount (30 wt %) of MACSF monomer (noted as CPE-3) showed the best performance. The nonflammable fluorosulfonyl group (a hydrophilic group of MACSF monomer) in the polymer matrix formed a wide channel, as a result of which Li ion can migrate easily via forming an ionic linkage. The CPE-3 electrolyte exhibited a low T g (−79 °C), excellent phase separation, high conductivity (σ) (ca. 3.5 × 10 −4 and 8.50 × 10 −3 S•cm −1 at 30 and 80 °C, respectively), and high flame retardancy. The battery performance of half-cell (LiFePO 4 /CPE-3/Li) and full cell (LiFePO 4 /CPE-3/graphite) with CPE-3 electrolyte were attractive: discharge capacities (155 and 152 mAh/g) with the capacity retentions of 96.17 and 95.17% after 500 cycles at 0.1 C rate for half-cell and full-cell LIBs, respectively.

Due to their high energy density and safety, polymer electrolytes are considered a promising alternative to the commercial liquid electrolytes used in lithium‐ion batteries (LIBs). However, in practical application, polymer electrolytes are limited by the high interface resistance between electrodes and electrolyte, leading to low ionic conductivity at room temperature (RT). In the present work, an in situ cationic ring‐opening technique is introduced using LiFSI as an initiator to address the issue of interfacial contact between electrolyte and electrodes in LIBs. Herein, a series of in situ poly(siloxane‐epoxy)‐based polymer electrolytes (PSEPEs) are synthesized, which present good thermal stability (158 °C), low glass transition temperature (Tg) (−42 °C), high ionic conductivity of 1.16 × 10–4 S cm–1, and good tLi+ of 0.61 at RT. The PSEPEs also show a wide electrochemical window (>4.7 V vs Li/Li+), and excellent compatibility with the lithium anode with an assembled LiFePO4/ PSEPEs /Li cell. This work contributes to developing a new polymer electrolyte fabricated by in situ cationic polymerization, and its effects on the reduction of the interfacial resistance of electrodes–electrolyte.

The polymer electrolytes are considered to be an alternative to liquid electrolytes for lithium-ion batteries because of their high thermal stability, flexibility, and wide applications. However, the polymer electrolytes have low ionic conductivity at room temperature due to the interfacial contact issue and the growing of lithium dendrites between the electrolytes/electrodes. In this study, we prepared gel polymer electrolytes (GPEs) through an in situ thermal-induced cationic ring-opening strategy, using LiFSI as an initiator. As-synthesized GPEs were characterized with a series of technologies. The as-synthesized PNDGE 1.5 presented good thermal stability (up to 150 °C), low glass transition temperature (Tg < −40 °C), high ionic conductivity (>10−4 S/cm), and good interfacial contact with the cell components and comparable anodic oxidation voltage (4.0 V). In addition, PNGDE 1.5 exhibited a discharge capacity of 131 mAh/g after 50 cycles at 0.2 C and had a 92% level of coulombic efficiency. Herein, these results can contribute to developing of new polymer electrolytes and offer the possibility of good compatibility through the in situ technique for Li-ion batteries.

Polymer electrolytes (PEs) based on poly(ethylene oxide) (PEO) have gained increasing interest in lithium-ion batteries (LIBs) and are expected to solve the safety issue of commercial liquid electrolytes due to their excellent thermal and mechanical stability, suppression of lithium dendrites and shortened battery assembly process. However, challenges, such as high interfacial resistance between electrolyte and electrodes and poor ionic conductivity (σ) at room temperature (RT), still limit the use of PEO-based PEs. In this work, an in situ PEO-based polymer electrolyte consisting of polyethylene glycol dimethacrylate (PEGDMA) 1000, lithium bis(fluorosulfonyl)imide (LiFSI) and DMF is cured on a LiFePO4 (LFP) cathode to address the above-mentioned issues. As a result, optimized PE shows a promising σ and lithium-ion transference number (tLi+) of 6.13 × 10−4 S cm−1 and 0.63 at RT and excellent thermal stability up to 136 °C. Moreover, the LiFePO4//Li cell assembled by in situ PE exhibits superior discharge capacity (141 mAh g−1) at 0.1 C, favorable Coulombic efficiency (97.6%) after 100 cycles and promising rate performance. This work contributes to modifying PEO-based PE to force the interfacial contact between the electrolyte and the electrode and to improve LIBs’ performance.

No abstract