Abstract
The lithium metal anode (LMA) has a promising theoretical specific capacity of 3860 mAh g-1 and is considered the next-generation anode for LIBs. Unfortunately, commercial electrolytes used nowadays have poor compatibility with LMAs and suffer from severe side reactions. Safety issues also arise from these electrolytes from inflammable carbonates and salts with poor thermal stability. Solid-state electrolytes (SSEs) can suppress lithium dendrites with mechanical strength and have better thermal stability. In-situ polymerization gel polymer electrolytes (GPE) have facile production methods and address the interface and interphase contact issues many SSEs suffer.The first study discusses the in-situ polymerized GPE system with poly(1,3-dioxolane) (PDOL) combined with the LHCE concept. A high concentration of LiTFSI and highly fluorinated solvents provided excellent rate performance with a capacity of 122 mAh g-1 at 3C, and a good capacity retention of 75.2% after 400 cycles with LFP|Li at 30 ℃. In contrast, Low Li ion transference numbers were measured, due to ion clusters of high-concentration LiTFSI salts. The next study focused on poly(vinyl ethylene carbonate) (PVEC) with a triple-salt system. With its unique mobile cyclic carbonate group, PVEC is known to provide high ionic conductivity. LiNO3 was also added to the LiTFSI/LiBOB system to produce stable SEI for LMA. PVEC electrolyte exhibited great compatibility with LMA, demonstrating coulombic efficiency of 93.7% with Cu|Li at the 50th cycle, and extremely high-capacity retention of 99.7% after 500 cycles with LCO|Li at 30 ℃. However, severe fluctuations in coulombic efficiency were observed due to aggressive side reactions ethylene carbonate (EC) exhibits. Both studies provided newly developed backbones for further improvement and a few considerations for preparing in-situ polymerized GPEs.
| Date of Award | 2023 |
|---|---|
| Original language | English |
| Awarding Institution |
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| Supervisor | Minhua SHAO (Supervisor) |
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- Standard