Enhanced Ion Transport Behaviors in Composite Polymer Electrolyte: the Case of Looser Chain Folding Structure

All-solid-state batteries based on composite polymer electrolytes (CPEs) have drawn significant attention due to their high energy density, security and flexibility. Usually, the improvement of electrochemical performance of CPEs is...

Excellent Performances of Composite Polymer Electrolytes with Porous Vinyl-Functionalized SiO2 Nanoparticles for Lithium Metal Batteries

Composite polymer electrolytes (CPEs) incorporate the advantages of solid polymer electrolytes (SPEs) and inorganic solid electrolytes (ISEs), which have shown huge potential in the application of safe lithium-metal batteries (LMBs). Effectively avoiding the agglomeration of inorganic fillers in the polymer matrix during the organic–inorganic mixing process is very important for the properties of the composite electrolyte. Herein, a partial cross-linked PEO-based CPE was prepared by porous vinyl-functionalized silicon (p-V-SiO2) nanoparticles as fillers and poly (ethylene glycol diacrylate) (PEGDA) as cross-linkers. By combining the mechanical rigidity of ceramic fillers and the flexibility of PEO, the as-made electrolyte membranes had excellent mechanical properties. The big special surface area and pore volume of nanoparticles inhibited PEO recrystallization and promoted the dissolution of lithium salt. Chemical bonding improved the interfacial compatibility between organic and inorganic materials and facilitated the homogenization of lithium-ion flow. As a result, the symmetric Li|CPE|Li cells could operate stably over 450 h without a short circuit. All solid Li|LiFePO4 batteries were constructed with this composite electrolyte and showed excellent rate and cycling performances. The first discharge-specific capacity of the assembled battery was 155.1 mA h g−1, and the capacity retention was 91% after operating for 300 cycles at 0.5 C. These results demonstrated that the chemical grafting of porous inorganic materials and cross-linking polymerization can greatly improve the properties of CPEs.

Enhanced Electrochemical Performance of Poly(ethylene oxide) Composite Polymer Electrolyte via Incorporating Lithiated Covalent Organic Framework

The lithiated covalent organic framework (named TpPa-SO3Li), which was prepared by a mild chemical lithiation strategy, was introduced in poly(ethylene oxide) (PEO) to produce the composite polymer electrolytes (CPEs). Li-ion can transfer along the PEO chain or across the layer of TpPa-SO3Li within the nanochannels, resulting in a high Li-ion conductivity of 3.01 × 10−4 S/cm at 60 °C. When the CPE with 0.75 wt.% TpPa-SO3Li was used in the LiFePO4||Li solid-state battery, the cell delivered a stable capacity of 125 mA·h/g after 250 cycles at 0.5 C, 60 °C. In comparison, the cell using the CPE without TpPa-SO3Li exhibited a capacity of only 118 mA·h/g.