Constructing Matching Cathode-Anode Interphases with Improved Chemo-mechanical Stability for High-Energy Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• High-energy-density lithium-ion batteries (LIBs) are crucial for applications like electric vehicles.
• Coupling nickel-rich layered oxide (NCM) cathodes with silicon (Si)-based anodes offers a promising route to increased energy density.
• However, interfacial instability on both electrodes leads to capacity fading and limited cycle life.

Purpose of the Study:

• To develop a multifunctional electrolyte additive for stabilizing interfaces in NCM/Si full cells.
• To mitigate the volume expansion of Si anodes and suppress parasitic reactions at the NCM cathode.
• To enhance the overall electrochemical performance and cycle life of high-energy LIBs.

Main Methods:

• Synthesis of lithium tetrafluoro(oxalato) phosphate as an electrolyte additive.
• Application of the additive in NCM/Si full cells.
• Electrochemical characterization, including cycling tests and impedance spectroscopy.
• Analysis of interfacial properties using techniques like XPS and SEM (implied).

Main Results:

• The additive successfully formed stable interphases (LiF, Li3PO4, P-containing polymer) on both NCM and Si.
• It effectively suppressed interfacial side reactions and mitigated Si anode volume changes.
• Demonstrated excellent cycling stability in 4.4 V 5 Ah 21700 cylindrical batteries, retaining 92.9% capacity after 300 cycles.

Conclusions:

• Lithium tetrafluoro(oxalato) phosphate is an effective multifunctional additive for stabilizing interfaces in high-energy NCM/Si LIBs.
• The strategy significantly improves cycle life and electrochemical performance.
• This work provides a new approach for interfacial engineering in advanced battery systems.