Bi-containing Electrolyte Enables Robust and Li Ion Conductive Solid Electrolyte Interphase for Advanced Lithium...

Area of Science:

• Materials Science
• Electrochemistry
• Battery Technology

Background:

• Lithium dendrite growth poses a significant safety risk in high-capacity lithium metal anodes for rechargeable batteries.
• The practical application of these anodes is limited by safety concerns associated with dendrite formation.

Purpose of the Study:

• To develop a robust and highly ionic conductive solid electrolyte interphase (SEI) layer to protect lithium metal anodes.
• To suppress lithium dendrite growth and improve the cycling stability of lithium metal anodes.

Main Methods:

• An in-situ SEI layer was constructed by introducing a trace additive, tetrapotassium heptaiodobismuthate (K4BiI7), into the electrolyte.
• Electrochemical cycling performance was evaluated at different current densities and capacities.
• In situ optical microscopy was used to observe dendrite suppression.

Main Results:

• The K4BiI7-added electrolyte demonstrated stable cycling of lithium metal anodes for over 600 cycles at 1.0 mA cm^-2/1.0 mAh cm^-2 and over 400 cycles at 5.0 mA cm^-2/5.0 mAh cm^-2.
• In situ optical microscopy confirmed the suppression of lithium dendrites, even at high current densities.
• The modified lithium anode exhibited an average Coulombic efficiency of 99.57% with reduced dendrite growth.
• Lithium-sulfur full cells with the modified electrolyte showed improved electrochemical performance.

Conclusions:

• The addition of K4BiI7 effectively creates a stable and highly ionic conductive SEI layer, significantly enhancing the safety and performance of lithium metal anodes.
• This cost-efficient method offers a promising strategy for advancing rechargeable battery technology by enabling the use of high-capacity lithium metal anodes.