Surface-treated cathode active material for aqueous lithium secondary batteries

LiMn2O4 Cathode for Aqueous Lithium Batteries with AlF3 Surface Coating to Prevent Mn Dissolution

This technology involves coating the surface of active materials, such as LiMn2O4, in aqueous lithium-ion batteries with metal fluorides or oxides like AlF3. This blocks side reactions between the electrolyte and the active material, preventing surface degradation and Mn ion dissolution.

Aqueous lithium-ion batteries have historically faced issues with rapid surface degradation of active materials due to the electrochemical instability of the electrolyte. In particular, LiMn2O4 has been limited by reduced cycle life and power performance caused by irreversible phase transitions and Mn ion dissolution.

This technology applies a uniform coating of AlF3, a metal fluoride, at 0.001–10 wt% of the cathode active material (optimally 2 wt% for LiMn2O4), suppressing side reactions in aqueous environments while maintaining the lithium-ion insertion/extraction structure. Suitable for indoor emergency power systems requiring low fire risk or hybrid capacitor-type storage devices using activated carbon anodes, it demonstrates durability with a capacity retention of approximately 90% after 100 cycles at 1C.

‍

‍

Key Features:

• A cathode comprising a cathode active material coated with 2 wt% AlF3 relative to the weight of LiMn2O4, acetylene black, and polytetrafluoroethylene
• An anode comprising activated carbon, paired with the coated cathode to form a lithium secondary battery cell
• A 1M Li2SO4 aqueous electrolyte that forms the cell together with a glass filter separator
• A coated cathode active material with an aluminum-rich surface, featuring an atomic concentration ratio of Al/Mn of 542%

‍