Realisation of an all solid state lithium battery using solid high temperature plastic crystal electrolytes...

Area of Science:

• Materials Science
• Electrochemistry
• Solid-State Chemistry

Background:

• Conventional lithium batteries utilize volatile and combustible electrolytes, posing safety risks and limiting specific energy.
• Developing safer, high-performance electrolytes is crucial for advancing lithium battery technology.

Purpose of the Study:

• To investigate the potential of an ionic organic plastic crystal (IOPC) material, N-ethyl-N-methylpyrrolidinium tetrafluoroborate ([C2mpyr][BF(4)]), as a solid-state electrolyte for lithium batteries.
• To evaluate the effect of incorporating lithium tetrafluoroborate (LiBF(4)) into the IOPC on its ionic conductivity and electrochemical performance.

Main Methods:

• Differential scanning calorimetry (DSC) and impedance spectroscopy were used to analyze the thermal properties and ionic conductivity of the composite electrolytes.
• Cyclic voltammetry and galvanostatic cycling of Li|LiFePO(4) and Li|Li symmetrical cells were performed to assess electrochemical stability and battery performance.

Main Results:

• Inclusion of LiBF(4) significantly increased ionic conductivity, particularly at higher temperatures, due to enhanced Li ion mobility in the plastic phase.
• Composite electrolytes with >5 mol% LiBF(4) exhibited ionic conductivity comparable to room temperature ionic liquids.
• The solid-state electrolyte demonstrated sufficient reversibility for lithium metal redox reactions, enabling successful battery cycling.

Conclusions:

• Ionic organic plastic crystals (IOPCs) doped with LiBF(4) offer a promising alternative to conventional liquid electrolytes for solid-state lithium batteries.
• This research demonstrates the first all-solid-state lithium battery utilizing IOPC-based solid electrolytes, enhancing safety and potentially specific energy.