Waste Not, Want Not: researchers Power Supercapacitors with Eggshells, Hemp, and Cement
BOSTON, MA - In a push for lasting energy storage, scientists are increasingly turning to unexpected sources – and waste products - to build the next generation of supercapacitors.Recent breakthroughs demonstrate the potential of materials like eggshells, hemp, and even cement to create functional, and surprisingly durable, energy storage devices.
The quest for eco-pleasant alternatives to traditional supercapacitor components, often reliant on scarce or environmentally damaging materials, is gaining momentum. These new approaches not only address sustainability concerns but also offer cost-effective solutions for energy storage.
Eggs-cellent Energy Storage
Researchers have successfully constructed a fully egg-based supercapacitor, utilizing every part of the egg. A team developed electrodes from carbonized eggshells, leveraging their calcium carbonate composition. Egg whites and yolks, mixed with potassium hydroxide and dried, formed a gel electrolyte. Crucially, the team repurposed eggshell membranes as separators, capitalizing on their naturally interlaced micrometer-sized fiber structure to facilitate ion transport.
The resulting supercapacitor proved flexible, maintaining capacitance even when bent or twisted. While retaining 80 percent of its original capacitance after 5,000 cycles, the performance is comparable to other supercapacitors built from natural materials.
Hemp-Derived Supercapacitors Rival Commercial Standards
In Türkiye, scientists at Ondokuz Mayıs University are harnessing the power of pomegranate hemp plants. In 2024, they utilized the stems of these plants to produce activated carbon for a supercapacitor electrode.The process involved drying,grinding,and chemically activating the hemp stems with sulfuric acid and potassium hydroxide.
The resulting supercapacitor demonstrated remarkable stability,retaining 98 percent of its original capacitance after 2,000 cycles – a performance level on par with supercapacitors made from conventional,non-biological materials. The hemp-derived carbon also boasted an energy density of 65 watt-hours per kilogram, aligning with commercial standards.
Cement: A Surprisingly Effective Electrode Material
Cement, a cornerstone of the construction industry, is also showing promise in the energy sector. A 2023 study from MIT researchers detailed the creation of electrodes using water, nearly pure carbon, and cement. The team theorizes a “synergy” between the hydrophilic cement and hydrophobic carbon enhances the electrodes’ ability to hold ions during charging.
Testing eight electrode variations, the researchers found the cement supercapacitors maintained capacitance with minimal loss even after 10,000 cycles. Calculations suggest a single supercapacitor could theoretically store around 10 kilowatt hours – enough to power roughly one-third of an average American’s daily energy needs.
