Phosphorus-induced Na_xPO_y-rich solid electrolyte interphase for durable and low-temperature sodium-ion batteries

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Sodium-ion batteries (SIBs) are emerging as a viable alternative to lithium-ion batteries.
• Carbon-based anodes in SIBs face challenges like capacity fading and poor low-temperature performance due to high interfacial impedance and slow ion transport.

Purpose of the Study:

• To address the limitations of carbon anodes in SIBs, particularly at low temperatures.
• To develop a novel anode material with enhanced cycling stability and ion conductivity across a wide temperature range.

Main Methods:

• A phosphorus-nitrogen co-doping strategy was employed to modify carbon-based anodes.
• The solid electrolyte interphase (SEI) was reconstructed using this co-doping approach.
• A Long Short-Term Memory (LSTM) model was utilized for capacity forecasting.

Main Results:

• The co-doping strategy enhanced electronic conductivity and defect density.
• Phosphorus incorporation led to a stable, amorphous Na_xPO_y-rich SEI layer, improving mechanical strength and Na⁺ migration.
• The optimized anode demonstrated high cycling stability at temperatures as low as -15 °C.
• LSTM model showed effectiveness in rapid capacity forecasting.

Conclusions:

• The phosphorus-nitrogen co-doping strategy offers a rational design for high-performance SIB anodes.
• This approach enables stable battery operation over a wide temperature range, addressing a key challenge in SIB technology.
• Preliminary full-cell tests confirmed the practical applicability of the developed anode.