Decoupling Electrode Environments with a pH-Asymmetric Biphase Electrolyte for High-Voltage Aqueous Rocking-Chair...

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• Aqueous batteries offer safety and cost benefits for energy storage but suffer from low voltage and energy density.
• Traditional homogeneous electrolytes limit the performance of aqueous battery systems.

Purpose of the Study:

• To design a novel electrolyte system for high-voltage aqueous rocking-chair lithium-ion batteries.
• To overcome the performance limitations of conventional aqueous battery electrolytes.

Main Methods:

• A pH-asymmetric biphase electrolyte (PSE) was engineered, combining an alkaline aqueous electrolyte (AE) and an ionic liquid-hydrofluoroether electrolyte (ILE).
• This PSE design decouples anode and cathode environments to accommodate distinct electrode requirements.
• The electrochemical stability window and performance of the dual-phase electrolyte system were evaluated.

Main Results:

• The PSE achieved a wide electrochemical stability window of 4.1 V, enabling the use of high-potential LiMn2O4 cathodes.
• The system demonstrated an enhanced average discharge voltage of 1.72 V (0.35 V increase) and an initial specific capacity of 220 mAh g-1.
• The high-pH AE effectively shifted the anode potential negatively, improving overall battery performance.

Conclusions:

• The pH-asymmetric biphase electrolyte design successfully enhances the voltage and energy density of aqueous lithium-ion batteries.
• This innovative approach provides a viable pathway for developing next-generation high-performance aqueous batteries.
• The study overcomes key limitations of traditional electrolytes, paving the way for safer and more efficient energy storage solutions.