聚合物基固态锂金属电池有望实现高能量密度和高安全性储能近年来受到学术界和业界的广泛关注。使用具有高离子电导率和稳定电极-电解质界面相容性的聚合物基电解质，可以确保实现高性能的固态锂金属电池。然而，如何有效地增强聚合物电解质中的锂离子传导仍然是实现固态锂金属电池实际应用的最大挑战。在所有的聚合物基电解质中，单离子导体（SIPC）中阴离子被共价地固定在聚合物链主链上，它具有高达1的锂离子迁移数（TLi+），是一种理想的聚合物电解质。本论文主要研究了聚碳酸酯基SIPC的设计、合成和应用，系统地研究了该SIPC的电化学性能、离子导电机理和电极-电解质界面的形成机制。 为了提高SIPC的离子导电性，通过精确调节锂离子和羰基/氰基之间的离子-偶极相互作用，制备了含有少量丁二腈作为增塑剂的聚碳酸酯基SIPC。SIPC具有优异的锂离子传导选择性（TLi+高达0.93）、约10-4 S cm-1的高室温离子电导率和宽的电化学稳定性窗口（> 4.5 V，相对于Li/Li+）。在对称锂电池和LiFePO4基固态锂金属电池的研究中，实验发现SIPC与锂金属表现出良好的电化学稳定性、可实现在室温和60 °C下的长稳定循环。 为了提高SIPC与金属锂的界面稳定性，将Li6.4La3Zr1.4Ta0.6O12（LLZTO）纳米颗粒分散到SIPC中制备了基于SIPC的复合电解质，它表现出高TLi+（0.90-0.97）、高室温离子电导率（>1.0×10-4 S cm-1），宽的电化学稳定性窗口（>5.0 V，相对于Li/Li+），同时能实现室温下对称金属锂电池循环达3200 h。LLZTO的增强作用，使复合电解质与金属锂之间形成了富含LiF和少量Li2CO3/RLiCO3/Li2Sx的界面层，这有利于均匀的锂沉积和快速的锂离子传导。 进一步，为了提高SIPC的耐高电压性能，将含氟官能团修饰到上述SIPC的主链中。含氟的SIPC显示出高室温离子电导率（1.2×10-4 S cm-1），高TLi+（0.93）和宽电化学稳定性窗口（5.12 V，相对于Li/Li+）。含氟SIPC可用于高电压正极，例如NCM811和高压LiCoO2。
Polymer-based solid-state lithium metal batteries (LMBs) are regarded as a promising candidate for high-energy-density and high-safety energy storage system by both academia and industry. To apply polymer-based electrolytes with high ionic conductivity and stable electrode-electrolyte interfacial compatibility can possibly ensure high performance in LMBs. However, to effectively enhance the Li ionic conduction in polymer electrolyte is still the biggest challenge for realizing the practical application of LMBs. Among all the polymer-based electrolytes, single ion polymer conductors (SIPCs) with covalently immobilized anions on the backbones of polymer chains in a kind of ideal polymer electrolytes with very high lithium transference number TLi+ value close to unity. This work thesis focuses on the design, synthesis, and application of polycarbonate-based SIPCs, and systematically iinvetigates the electrochemical properties, ionic conduction mechanism, and the formation of electrode-electrolyte interface of SIPC. Aiming at improving the ionic conductivity of SIPCs, a polycarbonate-based SIPC containing minimal succinonitrile as plasticizer was prepared by precisely regulating the ion–dipole interactions between Li+ and carbonyl/cyano groups. The SIPCs with exceptional selectivity for Li-ion conduction (Li-ion transference number up to 0.93), high room-temperature ionic conductivity of about 10-4 S cm-1, and a wide electrochemical stability window (> 4.5 V, vs. Li/Li+). The resulting SIPCs show an excellent electrochemical stability with Li metal during long-term cycling at room temperature and 60 °C in both symmetric Li cells and LiFePO4-based LMBs. By dispersing Li6.4La3Zr1.4Ta0.6O12 (LLZTO) nanoparticles into SIPC can significantly stabilize the interface between Li metal and SIPC electrolyte. This single-ion conductive composite polymer electrolyte (CPE) shows high TLi+ (0.90?0.97), high room-temperature (RT) ionic conductivity (>1.0×10-4 S cm-1), wide electrochemical stability window (>5.0 V, vs. Li/Li+), and excellent long-term cycling stability with Li metal at RT (3200 h). Based on the enhancement of LLZTO, the interface layer between Li metal and CPE consists of abundant LiF, and minimal Li2CO3/RLiCO3/Li2Sx, which is beneficial for uniform Li deposition and fast Li+ conduction. Furtherly, by applying fluoride containing functional groups into the backbones of the above SIPC, the newly prepared SIPC (F-SIPC) shows excellent high-voltage tolerance and can be applied in high voltage solid-state LMBs. The F-SIPC shows high RT ionic conductivity (1.2×10-4 S cm-1), high TLi+ (0.93), wide electrochemical stability window (5.12 V, vs. Li/Li+). The F-SIPC could be utilized in high-voltage cathodes, such as NCM811 and LiCoO2.
