Inner Helmholtz Plane Reconstruction Enables High‑Voltage Sodium‑Ion Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Parasitic reactions at the cathode-electrolyte interface cause capacity fading in high-voltage sodium-ion batteries (SIBs).
• Current strategies focus on bulk electrolyte properties, overlooking the inner Helmholtz plane (IHP) crucial for interfacial stability.

Purpose of the Study:

• To propose and validate a modulator-driven IHP reconstruction strategy for high-voltage SIBs.
• To enhance cathode-electrolyte interfacial chemistry and stability.

Main Methods:

• Utilized 4-amino-2-trifluoromethylbenzonitrile (ATMBN) as a molecular modulator.
• Investigated ATMBN's preferential adsorption in the IHP and PF₆^- enrichment.
• Analyzed the formation of a NaF/Na₃N-rich cathode-electrolyte interphase (CEI).

Main Results:

• Achieved 90.03% capacity retention in Na₃V₂O₂(PO₄)₂F (NVPOF) cathodes after 1000 cycles at 4.5 V.
• Demonstrated 80.33% capacity retention in a NaNi_0.33Fe_0.33Mn_0.33O₂ (NFM) || hard carbon (HC) pouch cell over 200 cycles (1.5-4.2 V).

Conclusions:

• The IHP reconstruction strategy effectively improves interfacial chemistry and stability in high-voltage SIBs.
• This approach offers a new paradigm for developing durable and high-performance SIBs.