Jin Lei, Jang Giseok, Lim Hyunmin, Zhang Wei, Park Sungjun, Jeon Minhyuk, Jang Hohyoun, Kim Whangi
Department of Applied Chemistry, Konkuk University, 268 Chungwon-daero, Chungju-si, Seoul 27478, Chungcheongbuk-do, Korea.
Polymers (Basel). 2022 Aug 23;14(17):3443. doi: 10.3390/polym14173443.
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 LiFePO (LFP) cathode to address the above-mentioned issues. As a result, optimized PE shows a promising σ and lithium-ion transference number () of 6.13 × 10 S cm and 0.63 at RT and excellent thermal stability up to 136 °C. Moreover, the LiFePO//Li cell assembled by in situ PE exhibits superior discharge capacity (141 mAh g) 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.
基于聚环氧乙烷（PEO）的聚合物电解质（PEs）在锂离子电池（LIBs）中受到越来越多的关注，由于其优异的热稳定性和机械稳定性、对锂枝晶的抑制作用以及缩短的电池组装工艺，有望解决商用液体电解质的安全问题。然而，诸如电解质与电极之间的高界面电阻以及室温（RT）下较差的离子电导率（σ）等挑战，仍然限制了基于PEO的PEs的应用。在这项工作中，一种由聚乙二醇二甲基丙烯酸酯（PEGDMA）1000、双（氟磺酰）亚胺锂（LiFSI）和N,N-二甲基甲酰胺（DMF）组成的原位PEO基聚合物电解质在磷酸铁锂（LFP）阴极上固化，以解决上述问题。结果，优化后的PE在室温下显示出有前景的6.13×10⁻⁵ S cm⁻¹的离子电导率（σ）和0.63的锂离子迁移数（t⁺），以及高达136℃的优异热稳定性。此外，由原位PE组装的LiFePO₄//Li电池在0.1 C下表现出优异的放电容量（141 mAh g⁻¹），100次循环后具有良好的库仑效率（97.6%）和有前景的倍率性能。这项工作有助于对基于PEO的PE进行改性，以促进电解质与电极之间的界面接触并提高LIBs的性能。
