A synergistic exploitation to produce high-voltage quasi-solid-state lithium metal batteries

The energy content increase is of paramount importance for the development of future Li-based batteries. Here, the authors propose a gel polymer electrolyte in combination with a positive electrode comprising of a Li-rich oxide active material and graphite to produce a high-energy Li metal cell. The current Li-based battery technology is limited in terms of energy contents. Therefore, several approaches are considered to improve the energy density of these energy storage devices. Here, we report the combination of a heteroatom-based gel polymer electrolyte with a hybrid cathode comprising of a Li-rich oxide active material and graphite conductive agent to produce a high-energy shuttle-relay Li metal battery, where additional capacity is generated from the electrolyte's anion shuttling at high voltages. The gel polymer electrolyte, prepared via in situ polymerization in an all-fluorinated electrolyte, shows adequate ionic conductivity (around 2 mS cm(-1) at 25 degrees C), oxidation stability (up to 5.5 V vs Li/Li+), compatibility with Li metal and safety aspects (i.e., non-flammability). The polymeric electrolyte allows for a reversible insertion of hexafluorophosphate anions into the conductive graphite (i.e., dual-ion mechanism) after the removal of Li ions from Li-rich oxide (i.e., rocking-chair mechanism).

Automated summary

This study reports a new type of gel polymer electrolyte combined with a hybrid cathode of Li-rich oxide active material and graphite to produce a high-energy Li metal battery, where additional capacity is generated through the anion shuttling mechanism of the electrolyte. The gel polymer electrolyte exhibits adequate ionic conductivity and oxidation stability, and is compatible and safe with Li metal.