Department of Chemistry and Life Science, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama 240-8501, Japan.
SANKEN (The Institute of Scientific and Industrial Research), Osaka University, Mihogaoka 8-1, Osaka 567-0047, Ibaraki, Japan.
ACS Appl Mater Interfaces. 2023 Mar 8;15(9):11741-11755. doi: 10.1021/acsami.2c21557. Epub 2023 Feb 21.
Na metal is a promising anode material for the preparation of next-generation high-energy-density sodium-ion batteries; however, the high reactivity of Na metal severely limits the choice of electrolyte. In addition, rapid charge-discharge battery systems require electrolytes with high Na-ion transport properties. Herein, we demonstrate a stable and high-rate sodium-metal battery enabled by a nonaqueous polyelectrolyte solution composed of a weakly coordinating polyanion-type Na salt, poly[(4-styrenesulfonyl)-(trifluoromethanesulfonyl)imide] (poly(NaSTFSI)) copolymerized with butyl acrylate, in a propylene carbonate solution. It was found that this concentrated polyelectrolyte solution exhibited a remarkably high Na-ion transference number ( = 0.9) and a high ionic conductivity (σ = 1.1 mS cm) at 60 °C. Furthermore, the surface of the Na electrode was modified with polyanion chains anchored via the partial decomposition of the electrolyte. The surface-tethered polyanion layer effectively suppressed the subsequent decomposition of the electrolyte, thereby enabling stable Na deposition/dissolution cycling. Finally, an assembled sodium-metal battery with a NaMnO cathode demonstrated an outstanding charge/discharge reversibility (Coulombic efficiency >99.8%) over 200 cycles while also exhibiting a high discharge rate (i.e., 45% capacity retention at 10 mA cm).
金属钠是制备下一代高能量密度钠离子电池的一种很有前途的阳极材料；然而，金属钠的高反应性严重限制了电解质的选择。此外，快速充放电电池系统需要具有高钠离子传输性能的电解质。在此，我们展示了一种由非水多阴离子型钠盐、聚(4-苯乙烯磺酰基)-(三氟甲磺酰基)亚胺与丙烯酸丁酯共聚而成的弱配位聚电解质溶液稳定、高倍率的钠金属电池，该溶液在碳酸丙烯酯溶液中。结果发现，这种浓缩的聚电解质溶液在 60°C 时表现出极高的钠离子迁移数（ = 0.9）和高离子电导率（σ = 1.1 mS cm）。此外，Na 电极的表面通过部分分解电解质而用锚定的聚阴离子链进行了修饰。表面固定的聚阴离子层有效地抑制了电解质的后续分解，从而实现了稳定的 Na 沉积/溶解循环。最后，与 NaMnO 阴极组装的钠金属电池在 200 次循环中表现出优异的充放电可逆性（库仑效率>99.8%），同时还表现出高放电速率（即在 10 mA cm 时具有 45%的容量保持率）。
