Solid‐state polymer electrolytes (SPEs) with high ionic conductivity are desirable for next generation lithium‐ and sodium‐ion batteries with enhanced safety and energy density. Nanoscale fillers such as alumina, silica, and titania nanoparticles are known to improve the ionic conduction of SPEs and the conductivity enhancement is more favorable for nanofillers with a smaller size. However, aggregation of nanoscale fillers in SPEs limits particle size reduction and, in turn, hinders ionic conductivity improvement. Here, a novel poly(ethylene oxide) (PEO)‐based nanocomposite polymer electrolyte (NPE) is exploited with carbon quantum dots (CQDs) that are enriched with oxygen‐containing functional groups. Well‐dispersed, 2.0–3.0 nm diameter CQDs offer numerous Lewis acid sites that effectively increase the dissociation degree of lithium and sodium salts, adsorption of anions, and the amorphicity of the PEO matrix. Thus, the PEO/CQDs‐Li electrolyte exhibits an exceptionally high ionic conductivity of 1.39 × 10⁻⁴ S cm⁻¹ and a high lithium transference number of 0.48. In addition, the PEO/CQDs‐Na electrolyte has ionic conductivity and sodium ion transference number values of 7.17 × 10⁻⁵ S cm⁻¹ and 0.42, respectively. It is further showed that all solid‐state lithium/sodium rechargeable batteries assembled with PEO/CQDs NPEs display excellent rate performance and cycling stability.

中文翻译：

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碳量子点纳米填料的高离子导电固态复合电解质

具有高离子电导率的固态聚合物电解质（SPE）对于具有更高安全性和能量密度的下一代锂离子电池和钠离子电池是理想的。已知纳米级填料（例如氧化铝，二氧化硅和二氧化钛纳米粒子）可改善SPE的离子传导性，而电导率增强对于尺寸更小的纳米填料更有利。但是，SPE中纳米级填料的聚集限制了粒径的减小，进而阻碍了离子电导率的提高。在这里，一种新型的基于聚环氧乙烷（PEO）的纳米复合聚合物电解质（NPE）被利用富含碳原子官能团的碳量子点（CQD）进行开发。分散良好，为2.0-3。直径为0 nm的CQD提供了许多路易斯酸位点，这些位点可有效提高锂盐和钠盐的离解度，阴离子的吸附率以及PEO基质的非晶性。因此，PEO / CQDs-Li电解质显示出1.39×10的极高离子电导率^-4 S cm ^-1和0.48的高锂转移数。另外，PEO / CQDs-Na电解质的离子电导率和钠离子转移数分别为7.17×10 ^-5 S cm ^-1和0.42。进一步表明，所有与PEO / CQDs NPE组装在一起的固态锂/钠可充电电池均具有出色的倍率性能和循环稳定性。