Why CO₂ capture via supercapacitive swing adsorption needs a theory, not just tweaks

Area of Science:

• Electrochemistry
• Environmental Science
• Materials Science

Background:

• Supercapacitive Swing Adsorption (SSA) is an electrochemical CO2 capture method using aqueous supercapacitors.
• SSA offers advantages like low energy use, long cycle life, and humidity tolerance.
• Current CO2 adsorption capacities are modest, and the capture mechanism is not fully understood.

Purpose of the Study:

• To address the limitations in SSA optimization due to a lack of mechanistic understanding.
• To map the empirical trends in SSA performance across various parameters.
• To identify constraints for a unifying theory of SSA and evaluate existing mechanistic proposals.

Main Methods:

• Empirical data analysis of SSA performance across different electrolytes, electrode materials, and charging protocols.
• Derivation of mechanistic constraints from observed trends.
• Assessment of leading mechanistic proposals against these constraints.

Main Results:

• Robust trends in SSA performance were identified across various experimental conditions.
• Existing mechanistic proposals show tensions and open questions when evaluated against derived constraints.
• A significant gap exists between empirical optimization and predictive design.

Conclusions:

• Resolving the operative capture mechanism is critical for advancing SSA technology.
• Future strategies should focus on closing mechanistic gaps to enable predictive design.
• This work aims to transition SSA from empirical optimization to a viable carbon capture technology.