Composite Solid Polymer Electrolyte with Garnet Nanosheets in Poly(ethylene oxide)

Abstract

Solid electrolytes potentially provide safety, Li dendrites blocking, and electrochemical stability in Li-metal batteries. Large efforts have been devoted to disperse ceramic nanoparticles in a poly­(ethylene oxide) (PEO) matrix to improve the ions transport. However, it is challengeable to create efficient framework for ions transport with nanoparticles. Here we report for the first time garnet nanosheets to provide interconnected Li-ions transport pathway in a PEO matrix. The garnet nanosheet fillers would not only facilitate ions transport but also enhance ionic conductivity in comparison with their nanoparticle counterparts. A composite solid polymer electrolyte containing 15 wt % garnet nanosheets exhibits a practically useful conductivity of 3.6 × 10–4 S cm–1 at room temperature. Besides, the composite electrolyte can robustly isolate Li dendrites in a symmetric lithium metal-composite electrolyte battery during reversible Li dissolution/deposition at a relatively low temperature of 40 °C. The symmetric cell with composite electrolyte shows flat voltage and low interfacial resistance over a galvanostatic cycling of 200 h at a current density of 0.1 mA cm–2. A solid-state Li/LiFePO4 battery with the composite polymer electrolyte exhibits a capacity of 98.1 mAh g–1 and a capacity retention of 97.5% after 30 cycles at a temperature of 40 °C. This finding provides a strategy to explore superionic conductors.

Homogeneous and Fast Ion Conduction of PEO‐Based Solid‐State Electrolyte at Low Temperature

“…Figure 3e summarizes the cycling performance and capacity retention of different PEO‐based electrolytes for Li|PEO‐based electrolyte|LiFePO 4 cells reported in the literature during the last two years (Table S3, Supporting Information). [ 29–31,36–46 ] Compared to other methods, our PEO‐based electrolytes are a simple and low‐cost way to make cells that work at both room temperature and lower temperature of 0 °C. Our Li|Homo‐SPE|LiFePO 4 cell presented good cycling performance (≈750 cycles) and high capacity retention (92.3%) at room temperature.…”

Designing Ceramic/Polymer Composite as Highly Ionic Conductive Solid‐State Electrolytes

“…In addition, the polymer crystallinity cannot be efficiently reduced if the nanosheets are too large. Therefore, many studies have tried to synthesize smaller size nanosheets [163] . Not only can reducing the size of nanosheets effectively avoid the above disadvantages, but smaller nanosheets can provide a larger effective interface than nanoparticles.…”

Toward safer solid-state lithium metal batteries: a review

“…66 Compounding inorganic SSEs with polymers is one of the most effective ways to improve their exibility. [67][68][69][70] For thermal stability, most inorganic SSEs are nonammable and exhibit high thermal stability. However, some research results show that some inorganic SSEs cannot maintain good thermal stability once thermal runaway occurs.…”