Wide-Temperature Electrolyte Design via Cation-Anion Solvation Engineering for 4.6 V Lithium-Ion Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Conventional lithium-ion batteries (LIBs) struggle with poor performance and safety issues at extreme temperatures due to unstable electrolytes.
• Ethylene carbonate (EC)-based electrolytes and lithium hexafluorophosphate (LiPF6) salts exhibit sluggish ion transport at low temperatures and decomposition at high temperatures.

Purpose of the Study:

• To develop advanced electrolytes for LIBs that operate reliably across a wide temperature range (-60°C to 45°C).
• To enhance the electrochemical stability and ionic conductivity of LIB electrolytes through synergistic cation-anion solvation engineering.

Main Methods:

• Developed EC-free carbonate solvents combined with a thermally stable ternary lithium salt.
• Engineered cation-anion solvation to improve desolvation kinetics and ionic conductivity.
• Investigated the resulting cathode-electrolyte interphase (CEI) formation on LiCoO2 (LCO) cathodes.

Main Results:

• The designed electrolyte demonstrated high ionic conductivity (0.19 mS cm⁻¹ at -60°C) and excellent thermal stability.
• Anion-participated solvation led to an inorganic-rich CEI, stabilizing the LCO cathode interface at high voltages.
• LCO cathodes maintained 88.9% capacity after 400 cycles at 25°C and 77.3% after 200 cycles at 45°C.

Conclusions:

• The cation-anion solvation strategy enables robust wide-temperature performance for LIBs.
• Achieved remarkable low-temperature capacity retention (110.1 mAh g⁻¹ at -35°C and 92.6 mAh g⁻¹ at -60°C).
• This approach offers a pathway for developing reliable LIBs for diverse operating conditions.