Nanohybrid Gel Polymer Electrolytes Based on Vinyl-Functionalized Mesoporous Silica Nanoparticles for Lithium Metal Batteries

초록

For the development of high-energy-density lithium metal batteries (LMBs), we designed nanohybrid gel polymer electrolytes (NGPEs). In NGPEs, vinyl-functionalized mesoporous silica nanoparticles (VMSNs, as reinforcement fillers) are integrated with cross-linkable poly(ethylene glycol) (PEG) oligomers and an ionic species mixture of ionic liquid and Li salt via a UV curing process. Two types of mesoporous silica nanoparticles with and without vinyl groups (VMSN vs MSN) are synthesized via the surface grafting method and used to prepare NGPE-VMSN and NGPE-MSN, where the corresponding silica nanoparticles are chemically and physically dispersed into the PEG network, respectively. The hybrid PEG network-derived NGPEs with mesoporous silica nanoparticles show attractive electrolyte properties, i.e., high shear storage modulus (G ' = 1.1 x 10(6) Pa), high ionic conductivity (sigma(dc) = 1 x 10(-4) S cm(-1)), and wide electrochemical stability window (ESW similar to 4.5 V), at room temperature. The resultant NGPE in the Li|Li cell also shows long-term cyclic stability without short-circuiting over 1000 h under 0.1 mA cm(-2), suggesting the NGPE's effectiveness in dendrite inhibition. Furthermore, the LiFePO4|NGPE|Li full cell presents a high specific capacity of 124 mAh g(-1) at 0.5C and stable cycling performances with 100% capacity retention and 99.5% Coulombic efficiency after 190 cycles at 25 degrees C. The NGPE demonstrates a simple design principle for replacing liquid electrolytes with solid-state electrolytes, allowing for a perfect complex between inorganic silica nanoparticles and organic PEG gel network through vinyl bonds on the MSN surface and PEG terminal group for high-energy-density LMBs.

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