Unique Carbonate-Based Single Ion Conducting Block Copolymers Enabling High-Voltage, All-Solid-State Lithium Metal...

Area of Science:

• Materials Science
• Electrochemistry
• Polymer Chemistry

Background:

• Advanced solid-state energy storage is crucial for low-emission vehicles (HEV/EV).
• High voltage operation and safety are key metrics for next-generation batteries.
• Current electrolytes face challenges in conductivity, stability, and safety.

Purpose of the Study:

• To design and synthesize novel single-ion conducting block copolymers.
• To enhance ionic conductivity, mechanical properties, and electrochemical stability.
• To enable safe, high-voltage operation in solid-state lithium-metal batteries.

Main Methods:

• Ring-opening polymerization (ROP) of trimethylene carbonate (TMC) using a hydroxyl-terminated RAFT agent.
• RAFT copolymerization of a lithium salt monomer and poly(ethylene glycol) methyl ether methacrylate.
• Characterization of viscoelastic properties, thermal stability, ionic conductivity, and electrochemical stability window.

Main Results:

• Synthesized block copolymers exhibit improved viscoelasticity and thermal stability (T_onset up to 155 °C).
• Achieved ionic conductivity up to 3.7 × 10⁻⁶ S cm⁻¹ at 70 °C with a high lithium-ion transference number (0.91).
• Demonstrated excellent electrochemical stability (>4.8 V vs Li⁺/Li), dendrite suppression, and compatibility with Li-metal anodes and composite cathodes (NMC, LFP).

Conclusions:

• The novel single-ion conducting block copolymers show significant potential for high-voltage solid-state batteries.
• Lab-scale cells demonstrated stable cycling performance at 70 °C, with enhanced rate capability upon propylene carbonate addition.
• These electrolytes represent a significant advancement for safe and practical lithium-metal battery technology.