Toward adequate control of internal interfaces utilizing nitrile-based electrolytes

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• Controlling internal interfaces in lithium-ion batteries is crucial for performance and longevity.
• Current methods for interface control, such as coating deposition, are often complex and difficult to implement.
• Parasitic reactions at the current collector interface pose a significant challenge for battery stability.

Purpose of the Study:

• To introduce novel electrolyte formulations for effective control of internal interfaces in lithium-ion batteries.
• To suppress aluminum dissolution and protect current collector interfaces under application-relevant conditions.
• To evaluate the performance and stability of these new electrolytes.

Main Methods:

• Development of electrolyte formulations based on aliphatic cyclic nitriles: cyclopentane-1-carbonitrile and cyclohexane-1-carbonitrile.
• Testing of these nitrile-based electrolytes in lithium nickel-manganese-cobalt oxide (LiNi_3/5Mn_1/5Co_1/5O₂, NMC622)||graphite full cells.
• Comparison of performance metrics, including capacity retention, oxidative stability, and thermal stability, against state-of-the-art organic carbonate-based electrolytes.

Main Results:

• Nitrile-based electrolytes successfully suppressed aluminum dissolution and controlled internal interfaces.
• These electrolytes exhibited higher intrinsic oxidative and thermal stabilities.
• Similar capacity retentions were observed in NMC622||graphite full cells compared to conventional electrolytes, even with lithium bis(trifluoro-methane)sulfonimide salt.
• The study highlighted the role of relative permittivity, ion dissociation, and viscosity in protecting current collector interfaces.

Conclusions:

• Aliphatic cyclic nitrile-based electrolytes offer a promising alternative for enhancing lithium-ion battery stability.
• These electrolytes provide effective protection against aluminum dissolution and parasitic reactions at current collector interfaces.
• Electrolyte properties like permittivity, ion dissociation, and viscosity are critical factors for interface management in batteries.