Scaleup Sodium-Ion Capacitor Ah-Level Pouch Cells Enable 100 C Ultrafast Charging Capabilities

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Traditional hybrid ion capacitors suffer from limited energy storage capacity due to narrow potential windows and require complex pre-lithiation/presodiation steps.
• Activated carbon negative electrodes (AC NE) typically form solid electrolyte interphase (SEI) layers, hindering performance within certain voltage ranges.

Purpose of the Study:

• To develop a high-performance sodium-ion capacitor (SIC) that overcomes the limitations of traditional hybrid ion capacitors.
• To demonstrate the feasibility of using activated carbon negative electrodes (AC NE) in a wide potential window without SEI formation.
• To achieve high energy density, power density, and long-term stability in a practical, easily manufactured device.

Main Methods:

• Utilized activated carbon as the negative electrode material, operating in a wide potential window (3-0.05 V vs. Na+/Na) without SEI layer influence.
• Fabricated a 1.6 Ah sodium-ion capacitor (SIC) pouch cell.
• Conducted electrochemical testing, including cycling stability, rate capability, and safety assessments (nail penetration, thermal runaway).

Main Results:

• The AC NE exhibited an ultrahigh electric double-layer (EDL) capacitive storage capacity of 145 mAh g⁻¹ (177 F g⁻¹).
• The SIC pouch cell delivered a high energy density of 42 Wh kg⁻¹, achieved 57% state of charge (SoC) at 100 C charging rate, and demonstrated stable cycling over 10,000 cycles.
• The device passed rigorous safety tests and was assembled without presodiation, significantly reducing manufacturing complexity and cost.

Conclusions:

• The developed sodium-ion capacitor represents a significant advancement, offering high energy density coupled with capacitor-level power density, long-term cyclability, and simplified assembly.
• This work paves the way for next-generation electrochemical capacitors with improved performance and manufacturing feasibility.
• The absence of pre-sodiation in the assembly process highlights a more cost-effective and scalable approach to energy storage device fabrication.