A team from Politecnico di Torino and the Istituto Italiano di Tecnologia has developed an energy harvesting system that departs from conventional aqueous-based carbon capture models. Instead of relying on water-based electrolytes or chemical scrubbing with high enthalpy penalties, the study leverages ionic liquids (ILs)—low-volatility, tunable solvents known for their stability and high CO₂ absorption capacity.
Unlike traditional capacitive mixing (CapMix) systems, which depend on electric double-layer (EDL) expansion, this new method operates through two mechanisms: ion reorientation at the electrode interface and bulk potential differences between CO₂-saturated and unsaturated ionic liquids. Classical molecular dynamics simulations validated that the voltage change during CO₂ capture is driven not by changes in ion concentration gradients, but by alterations in molecular orientation and interfacial dipoles.
Optimizations further enhanced the system's performance. Diluting the ionic liquid [DBUH][Im] with propylene carbonate (PC) significantly reduced viscosity, improved ionic mobility, and minimized self-discharge losses. Activated carbon coatings on gas diffusion electrodes increased capacitance, enabling greater energy recovery per cycle.
As a result, the optimized device achieved an energy density of 40 μWh/m² and a power density of 0.8 mW/m²—metrics comparable to emerging technologies in the nonconventional energy storage sector. Importantly, the system operates efficiently at or near open-circuit voltage, eliminating the need for an external power supply during operation and enabling energy harvesting during both CO₂ absorption and desorption phases.
![Schematic of the electrochemical cell, b) CO2 absorption mechanism by [DBUH][Im].](https://advanced.onlinelibrary.wiley.com/cms/asset/80ee74d5-27b2-40a7-bead-7222d1e06880/aesr12775-fig-0001-m.jpg)
This innovation opens new opportunities for integrating carbon capture and energy recovery into industrial emissions systems. Facilities could potentially transform waste CO₂ streams into a minor but meaningful source of auxiliary power, supporting operational sustainability goals while advancing circular economy initiatives.
As industries seek new approaches to decarbonize without incurring prohibitive costs, ionic liquid-based electrochemical capacitors represent a promising step forward. By combining CO₂ capture with direct energy harvesting, this technology not only mitigates emissions but actively contributes to a more resilient and efficient energy landscape.
