Nature Materials ( IF 41.2 ) Pub Date : 2022-07-28 , DOI: 10.1038/s41563-022-01319-w Fangfang Chen 1, 2 , Xiaoen Wang 1 , Michel Armand 3 , Maria Forsyth 1, 2
Polymer electrolytes provide a safe solution for future solid-state high-energy-density batteries. Materials that meet the simultaneous requirement of high ionic conductivity and high transference number remain a challenge, in particular for new battery chemistries beyond lithium such as Na, K and Mg. Herein, we demonstrate the versatility of a polymeric ionic liquid (PolyIL) as a polymer solvent to achieve this goal for both Na and K. Using molecular simulations, we predict and elucidate fast alkali metal ion transport in PolyILs through a structural diffusion mechanism in a polymer-in-salt environment, facilitating a high metal ion transference number simultaneously. Experimental validation of these computationally designed Na and K polymer electrolytes shows good ionic conductivities up to 1.0 × 10−3 S cm−1 at 80 °C and a Na+ transference number of ~0.57. An electrochemical cycling test on a Na∣2:1 NaFSI/PolyIL∣Na symmetric cell also demonstrates an overpotential of 100 mV at a current density of 0.5 mA cm−2 and stable long-term Na plating/stripping performance of more than 100 hours. PolyIL-based polymer-in-salt strategies for new solid-state electrolytes thus offer an alternative route to design high-performance next-generation sustainable battery chemistries.
中文翻译:
用于快速金属离子传导和固态电池应用的阳离子聚合物盐电解质
聚合物电解质为未来的固态高能量密度电池提供了安全的解决方案。同时满足高离子电导率和高迁移数要求的材料仍然是一个挑战,特别是对于锂以外的新型电池化学物质,如钠、钾和镁。在这里,我们展示了聚合物离子液体 (PolyIL) 作为聚合物溶剂的多功能性,以实现 Na 和 K 的这一目标。使用分子模拟,我们通过结构扩散机制预测和阐明 PolyIL 中的快速碱金属离子传输聚合物盐环境,同时促进高金属离子迁移数。这些计算设计的 Na 和 K 聚合物电解质的实验验证显示出高达 1.0 × 10 -3 S cm的良好离子电导率-1在 80 °C 下,Na +转移数约为 0.57。在 Na ∣ 2:1 NaFSI/PolyIL ∣ Na 对称电池上进行的电化学循环测试也证明了在 0.5 mA cm -2的电流密度下的 100 mV 过电位和超过 100 小时的稳定的长期 Na 电镀/剥离性能. 因此,用于新型固态电解质的基于 PolyIL 的盐包聚合物策略为设计高性能下一代可持续电池化学物质提供了另一种途径。