Stable Photothermal Conversion Fillers Enable Subzero-Temperature Applications of PEO-Based Solid-State Lithium...

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Low-temperature operation is a major challenge for all-solid-state batteries (ASSBs).
• Polyethylene oxide (PEO)-based solid-state electrolytes (SSEs) show poor ionic conductivity at ambient and subzero temperatures, requiring external heating (60-80°C).
• This heating requirement limits PEO-based ASSB applications in cold environments and consumes extra energy.

Purpose of the Study:

• To develop a PEO-based SSE with enhanced ionic conductivity and electrochemical stability at room temperature.
• To enable efficient low-temperature operation of ASSBs without external heating.
• To improve the practical applicability of ASSBs in subzero conditions.

Main Methods:

• Incorporation of lithiated poly(3,4-dioxythiophene) (LiPHT) photothermal conversion filler into PEO-based SSEs.
• Fabrication of a transparent battery utilizing the PEO-LiPHT composite as both electrolyte and photothermal heater.
• Testing of the ASSB's performance, including ionic conductivity, electrochemical window, and discharge capacity at -15°C under ambient light.

Main Results:

• The PEO-LiPHT SSE achieved an ionic conductivity of 1.34 × 10⁻⁴ S cm⁻¹ and an electrochemical window of 4.55 V vs. Li/Li⁺ at room temperature.
• The composite layer demonstrated efficient photothermal conversion and rapid light-induced heating.
• The ASSB exhibited a discharge capacity of 131.3 mA h g⁻¹ at 0.5 C at -15°C, owing to the in situ photothermal self-heating effect.

Conclusions:

• The PEO-LiPHT composite effectively addresses the low-temperature limitations of PEO-based SSEs.
• In situ photothermal self-heating enables optimal operating temperatures for ASSBs in subzero environments.
• This approach provides a promising strategy for developing high-performance ASSBs for demanding low-temperature applications.