Xin Mingyang, Zhang Yimu, Liu Zhenhua, Zhang Yuqing, Zhai Yutong, Xie Haiming, Liu Yulong
School of Chemistry, Northeast Normal University, Changchun 130024, China.
Molecules. 2024 May 23;29(11):2454. doi: 10.3390/molecules29112454.
To realize high-energy-density Li metal batteries at low temperatures, a new electrolyte is needed to solve the high-voltage compatibility and fast lithium-ion de-solvation process. A gel polymer electrolyte with a small-molecular-weight polymer is widely investigated by combining the merits of a solid polymer electrolyte (SPE) and liquid electrolyte (LE). Herein, we present a new gel polymer electrolyte (P-DOL) by the lithium difluoro(oxalate)borate (LiDFOB)-initiated polymerization process using 1,3-dioxolane (DOL) as a monomer solvent. The P-DOL presents excellent ionic conductivity (1.12 × 10 S cm) at -20 °C, with an oxidation potential of 4.8 V. The Li‖LiCoO cell stably cycled at 4.3 V under room temperature, with a discharge capacity of 130 mAh g at 0.5 C and a capacity retention rate of 86.4% after 50 cycles. Moreover, a high-Ni-content LiNiCoMnO (NCM811) cell can steadily run for 120 cycles at -20 °C, with a capacity retention of 88.4%. The underlying mechanism of high-voltage compatibility originates from the dense and robust B- and F-rich cathode interface layer (CEI) formed at the cathode interface. Our report will shed light on the real application of Li metal batteries under all-climate conditions in the future.
为了在低温下实现高能量密度的锂金属电池，需要一种新型电解质来解决高电压兼容性和快速锂离子去溶剂化过程的问题。通过结合固体聚合物电解质（SPE）和液体电解质（LE）的优点，一种含有小分子聚合物的凝胶聚合物电解质受到了广泛研究。在此，我们通过以二氟草酸硼酸锂（LiDFOB）引发的聚合过程，使用1,3 - 二氧戊环（DOL）作为单体溶剂，制备了一种新型凝胶聚合物电解质（P - DOL）。P - DOL在-20°C时表现出优异的离子电导率（1.12×10 S cm），氧化电位为4.8 V。Li‖LiCoO电池在室温下于4.3 V稳定循环，在0.5 C下放电容量为130 mAh g，50次循环后容量保持率为86.4%。此外，高镍含量的LiNiCoMnO（NCM811）电池在-20°C下可稳定运行120次循环，容量保持率为88.4%。高电压兼容性的潜在机制源于在阴极界面形成的致密且坚固的富含B和F的阴极界面层（CEI）。我们的报告将为未来锂金属电池在全气候条件下的实际应用提供启示。
