A Deep Eutectic Solvent Electrolyte Enables Planar Cu Deposition and High-Temperature Cu-MnO₂ Battery

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• Aqueous copper-ion batteries offer high theoretical capacity but face challenges like copper dendrite growth, limited cycle life, and poor high-temperature stability.
• Current electrolytes struggle to mitigate these issues, hindering practical applications of copper-ion battery technology.

Purpose of the Study:

• To develop a novel deep eutectic solvent (DES) electrolyte for aqueous copper-ion batteries.
• To address challenges of copper dendrite growth, cycle life, and high-temperature performance.
• To investigate the mechanism of DES electrolyte on copper deposition behavior.

Main Methods:

• Utilized Fourier transform infrared spectroscopy (FTIR) to analyze electrolyte-ion interactions.
• Employed molecular dynamics (MD) simulations to understand copper deposition modulation.
• Conducted electrochemical cycling tests for copper-ion batteries and full cells.

Main Results:

• The DES electrolyte demonstrated coordination with Cu2+ ions, effectively modulating copper deposition.
• Achieved planar copper deposition, significantly extending cycle life from 730 h to 6000 h.
• A high-temperature Cu─MnO2 full cell maintained 174.8 mAh g-1 after 300 cycles at 50 °C and 2 A g-1.

Conclusions:

• The developed DES electrolyte is a promising solution for stable and long-lasting aqueous copper-ion batteries.
• The findings highlight the potential of DES electrolytes for advanced energy storage under demanding conditions.
• This work offers a new strategy for improving the performance and safety of copper-ion batteries.