In Situ Lithiated Reference Electrode: Four Electrode Design for In-operando Impedance Spectroscopy

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• Extending operating voltage of lithium-ion batteries (LIBs) increases energy density but accelerates performance decay.
• Understanding LIB degradation is challenging due to combined electrochemical signals from all cell components.
• Reference electrodes are crucial for individually probing electrode reactions and diagnosing degradation.

Purpose of the Study:

• To introduce a novel test cell design for LIBs that accommodates multiple reference electrodes.
• To present suitable reference electrodes for specific diagnostic measurements.
• To detail assembly procedures for maximizing experimental accuracy in LIB analysis.

Main Methods:

• Design and construction of a specialized test cell capable of housing multiple reference electrodes.
• Selection and characterization of appropriate reference electrodes for distinct electrochemical measurements within LIBs.
• Development of precise assembly protocols to ensure high-fidelity experimental data.

Main Results:

• The developed test cell enables individual monitoring of cathode and anode electrochemical reactions.
• Variations in cathode voltage ranges indicate changes in cyclable lithium ion inventory.
• Electrode-specific impedance measurements reveal structural evolution of battery interphases.

Conclusions:

• The multi-reference electrode test cell significantly enhances diagnostic capabilities for LIBs.
• This approach provides valuable insights for optimizing individual battery components and improving long-term stability.
• Accurate measurements are achievable through careful electrode selection and assembly procedures.