Double-Protected Layers with Solid-Liquid Hybrid Electrolytes for Long-Cycle-Life Lithium Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Liquid electrolytes in lithium-ion batteries (LIBs) pose safety risks like leakage and limit energy density.
• Solid electrolytes offer enhanced safety and high-temperature performance but face challenges with interface impedance and reactivity with lithium metal.
• Lithium aluminum titanium phosphate (LATP) solid electrolytes exhibit rigidity, leading to high interfacial resistance and undesirable reactions with lithium metal.

Purpose of the Study:

• To address the limitations of solid electrolytes in LIBs by reducing interface impedance and preventing side reactions with lithium metal.
• To develop a stable solid-electrolyte interface using a hybrid electrolyte approach.
• To enhance the overall performance and safety of LIBs utilizing solid-state battery technology.

Main Methods:

• Fabrication of solid-liquid hybrid electrolytes by introducing liquid electrolyte at the LATP/electrode interface.
• In situ curing of a composite polymer electrolyte (CPE) protective film (PVDF, SN, LiTFSI) at the LATP/Li interface.
• Electrochemical testing of LiFePO4/LATP-12% LE-CPE/Li and NCM622/PVDF-LATP-12% LE/Li battery systems.

Main Results:

• The LiFePO4/LATP-12% LE-CPE/Li system achieved a discharge specific capacity of 150 mAh g⁻¹ with 96% capacity retention after 250 cycles.
• The NCM622/PVDF-LATP-12% LE/Li system demonstrated an initial reversible capacity of 170 mAh g⁻¹.
• The hybrid electrolyte approach effectively reduced interface impedance and mitigated side reactions between LATP and lithium metal.

Conclusions:

• The developed solid-liquid hybrid electrolyte system significantly improves the stability and performance of LIBs with LATP solid electrolytes.
• The in situ protective film successfully prevents detrimental side reactions at the LATP/lithium metal interface.
• This strategy offers a promising pathway for advancing solid-state battery technology by enhancing interfacial compatibility and safety.