Min Jungki, Liang Zhaohui, Pietra Nicholas F, Connor Callum, Madsen Louis A, Lin Feng
Department of Chemistry, Virginia Tech, Blacksburg, Virginia 24061, United States.
Macromolecules Innovation Institute, Virginia Tech, Blacksburg, Virginia 24061, United States.
ACS Appl Mater Interfaces. 2025 Jun 25;17(25):36639-36649. doi: 10.1021/acsami.5c04566. Epub 2025 Jun 15.
Polymer electrolytes are promising candidates for enabling safe, high-energy lithium batteries, particularly when paired with high-voltage layered oxide cathodes and lithium metal anodes. However, challenges at electrode|electrolyte interfaces, such as parasitic side reactions and electrolyte decomposition, have hindered the widespread adoption of polymer electrolyte-based high-voltage lithium batteries. To address these issues, this study introduces molecular ionic composites (MICs) as free-standing polymer electrolyte membranes, eliminating the need for any additional liquid electrolytes during cell assembly. MICs consist of a charged rigid-rod ionic polymer, poly-2,2″-disulfonyl-4,4'-benzidine terephthalamide (PBDT), combined with mobile ions from ionic liquids, lithium salts, and functional additives. The associative interactions between PBDT and these ions create a tunable platform with exceptional mechanical strength, moderate ionic conductivity, and enhanced electrochemical stability of polymer electrolyte over a wide temperature range. The optimized MIC electrolytes exhibit high ionic conductivity (3.21 mS cm at 60 °C), a wide electrochemical stability window (5 V vs Li|Li based on linear sweep voltammetry), and excellent mechanical properties (tensile strength of 6.3 MPa, elastic modulus of 450 MPa). Furthermore, MICs enable good cycling stability in NMC811||Li metal cells, delivering an initial specific discharge capacity of 212 mAh g and 93% capacity retention after 100 cycles at 2.8-4.4 V, C/3, and 60 °C. These results underscore the potential of MICs as a promising electrolyte platform for next-generation high-voltage lithium batteries and broader electrochemical energy storage applications.
聚合物电解质是实现安全、高能量锂电池的有前景的候选材料，特别是与高压层状氧化物阴极和锂金属阳极配对使用时。然而，电极|电解质界面处的挑战，如寄生副反应和电解质分解，阻碍了基于聚合物电解质的高压锂电池的广泛应用。为了解决这些问题，本研究引入了分子离子复合材料（MICs）作为独立的聚合物电解质膜，在电池组装过程中无需任何额外的液体电解质。MICs由带电荷的刚性棒状离子聚合物聚-2,2″-二磺酰基-4,4'-联苯二甲酰胺（PBDT）与来自离子液体、锂盐和功能添加剂的移动离子组成。PBDT与这些离子之间的缔合相互作用创建了一个可调谐平台，具有出色的机械强度、适度的离子电导率，并在很宽的温度范围内提高了聚合物电解质的电化学稳定性。优化后的MIC电解质表现出高离子电导率（60°C时为3.21 mS cm）、宽电化学稳定性窗口（基于线性扫描伏安法，相对于Li|Li为5 V）和出色的机械性能（拉伸强度为6.3 MPa，弹性模量为450 MPa）。此外，MICs在NMC811||Li金属电池中实现了良好的循环稳定性，在2.8-4.4 V、C/3和60°C下100次循环后，初始比放电容量为212 mAh g，容量保持率为93%。这些结果强调了MICs作为下一代高压锂电池和更广泛的电化学储能应用的有前景的电解质平台的潜力。
