# Supercapacitive CO2 Capture through a Scalable, Aqueous, Neutral Polymer‐Based Electrolyte

## TL;DR

A new water-based polymer electrolyte enables efficient and scalable CO2 capture in supercapacitor cells under neutral pH conditions.

## Contribution

A scalable, aqueous, neutral polymer-based electrolyte for CO2 capture in supercapacitors is developed, achieving high CO2 adsorption.

## Key findings

- CO2 capture of up to 356 mmol per kilogram of electrode material is achieved using negative charge protocols.
- The system operates at 2.5 V and 40°C under neutral pH conditions with excellent stability and corrosion resistance.
- The electrolyte increases gravimetric energy stored threefold compared to similar devices using microporous carbon.

## Abstract

Aqueous electrolytes offer a safer, more cost‐effective, and scalable solution for electrochemical CO2 capture. Herein, electrolytes that combine harmless polyethylene glycol with slightly salty water are developed, which enables the capture of CO2 in a supercapacitor cell of up to 79 mmol of CO2 per kilogram of electrode material while operating at a current density of 30 mA g−1, a voltage of 2.5 V, at 40 °C, and under neutral pH conditions. Interestingly, applying negative charge protocols up to −2.5 V increases the amount of CO2 adsorbed per kilogram of electrode to 356 mmol. This is attributed to both the ejection of preadsorbed bicarbonate species from the pores and their slow migration kinetics near the electrode exposed to CO2 gas toward the positively charged counter electrode. This finding indicates that the CO2 capture and release mechanism exhibits no dependence on the direction of the charge. These polymer electrolytes lead to a threefold increase in the gravimetric energy stored compared to similar devices operating at ≈1 V that utilize microporous carbon electrode materials. The system also reveals excellent stability and corrosion resistance under long‐term cycling at high voltages. This advanced technology marks a major advancement in sustainable carbon capture solutions.

Slowly but surely. Safe, pH‐neutral, and scalable water‐based polymer electrolyte allows for the capture of CO2 within a supercapacitor cell. By applying negative charge protocols of up to −2.5 V, it achieves the capture of up to 356 mmol of CO2 per kilogram of electrode material. This process likely occurs due to the slow migration of bicarbonate species toward the counter electrode .© 2025 WILEY‐VCH GmbH