The accumulation of CO2 in the atmosphere through burning of fossil fuels is largely responsible for the rapid increase in global temperature causing climate change. To achieve net-zero emission of anthropogenic CO2 by the end of twenty-first century, there is currently an urgent need to develop energy-efficient, cost-effective, and scalable methods that efficiently capture CO2 both from centralized (e.g., flue gas) and decentralized (e.g., air) sources. Electrochemical CO2 capture methods are currently gaining increased attention. These methods rely solely on the application of potential or current to capture CO2 either through pH modulation, redox-active agents, or capacitive adsorption. The majority of these electrochemical methods require expensive ion-selective membranes, electrode materials, and solvents. In contrast, supercapacitive Swing Adsorption (SSA) only requires the use of robust, inexpensive, and environmentally benign activated carbon electrodes, a separator, and an aqueous electrolyte to capture and release CO2. Compared to redox-techniques, it offers the advantage of longer sorbent (electrode) lifetime, high round-trip energy efficiency, and fast charge/discharge cycles. Until recently, the performance of SSA was largely limited by the low CO2 sorption capacity (∼60 mmol/kg) and slow sorption rate (24 μmol.kg -1 .s -1 ). Recently, our group discovered that biomass-derived activated carbons from garlic skin, garlic roots, and garlic clove powder lead to an increase of the gravimetric adsorption capacity by about four times (up to 273 mmol/kg) and the adsorption rate by about three times (up to 84 µmol.kg -1 s - 1 ). Around the same time, Forse et al. reported that the gravimetric sorption capacity of SSA can be increased from 50 to 112 mmol.kg by charging the electrodes between -1 V to +1 V instead of -1 V to 0 V, but this approach resulted in a very high energy consumption (751 kJ/mol CO2). To meet the 2025 DOE cost target for post-combustion CO2 capture (∼ 40$/ton), a significant decrease in SSA energy consumption and further increase in SSA adsorption capacity is desirable. To reduce cost, the use of thicker and denser electrodes with a higher mass loading is advantageous because it increases the ratio of the adsorptive (activated carbon) versus the non-adsorptive (separator, gas diffusion layer, current collector) components. One challenge is to maintain high capacitances, high CO2 sorption capacity, fast charge transport kinetics, fast sorption rates and low energy consumption at higher mass loadings due to less efficient gas permeation and ion diffusion as well as a greater resistor length. Herein, we show the overcoming of this challenge through the demonstration of novel, highmass loading garlic-roots derived activated carbon-based (GR-AC) electrodes with improved adsorptive and energetic performance. We show that the SSA adsorption capacity can be further increased by increasing the voltage window without substantially compromising the energy consumption. Although the thermodynamic potential window of aqueous supercapacitors is limited to 1.23 V, a higher voltage window is possible because of the high hydrogen evolution and oxygen evolution reaction overpotential of carbon-based electrodes in neutral electrolytes.