In a groundbreaking study, two of humanity’s most enduring materials, cement, and carbon black, are poised to usher in a cost-effective energy storage system. This novel technology holds the potential to support the utilization of renewable energy sources such as solar, wind, and tidal power by ensuring the stability of energy networks, even in the face of fluctuating renewable energy supplies.
The research reveals that these two materials, when combined with water, can yield a supercapacitor—a viable alternative to traditional batteries—for storing electrical energy. MIT researchers leading the project envision that these supercapacitors could be seamlessly integrated into various applications. For instance, they propose embedding them within the concrete foundation of a house, where they could accumulate an entire day’s worth of energy without significantly increasing construction costs, all while maintaining structural integrity. The researchers also envision concrete roadways that provide wireless recharging capabilities for electric vehicles as they traverse these roads.
This innovative technology is discussed in detail in a recent paper published in the journal PNAS, co-authored by MIT professors Franz-Josef Ulm, Admir Masic, and Yang-Shao Horn, along with four other contributors from MIT and the Wyss Institute.
At its core, a capacitor is a simple device, comprising two electrically conductive plates immersed in an electrolyte and separated by a membrane. When voltage is applied across the capacitor, ions from the electrolyte accumulate on the plates, creating an electric field between them. The separation of charges allows the capacitor to store energy and discharge it rapidly when needed. Supercapacitors are a variant of capacitors known for their capacity to store exceptionally large amounts of charge.
The key to the new supercapacitors developed by this team lies in their creation of a cement-based material with an extraordinarily high internal surface area. This feat is achieved through a dense, interconnected network of conductive material within the material’s bulk volume. The researchers introduced carbon black, a highly conductive substance, into a concrete mixture along with cement powder and water. As the mixture cures, the water naturally forms openings within the structure, and carbon migrates into these spaces, creating wire-like structures within the hardened cement. These structures exhibit a fractal-like pattern, with smaller branches sprouting from larger ones, resulting in an extensive surface area within a relatively compact volume. Subsequently, the material is soaked in a standard electrolyte material, such as potassium chloride, to introduce charged particles that accumulate on the carbon structures. When two electrodes made from this material are separated by a thin space or insulating layer, they form a powerful supercapacitor.
Supercapacitors produced using this novel material hold enormous potential for aiding the global transition to renewable energy. Wind, solar, and tidal power, the primary sources of emission-free energy, often generate power at times that do not align with peak electricity demand. Hence, effective energy storage solutions are imperative. According to Ulm, “There is a huge need for big energy storage,” and existing batteries, which rely on materials like lithium with limited supply, tend to be expensive. The unique aspect of this technology lies in the ubiquity of cement, making it a cost-effective alternative.
The research team calculated that a 45-cubic-meter block of nanocarbon-black-doped concrete could store approximately 10 kilowatt-hours of energy, equivalent to the average daily electricity usage for a household. These supercapacitors have the advantage of rapid charging and discharging, a marked improvement over traditional batteries.
While initial applications may include remote homes, isolated buildings, or off-grid shelters powered by solar panels connected to cement supercapacitors, the scalability of this technology is immense. The energy storage capacity is directly proportional to the volume of the electrodes, making it adaptable for various purposes. The system’s properties can be tailored by adjusting the mixture to meet specific application requirements.
Furthermore, the researchers envision a multifunctional application for this material. In addition to storing energy, the same concrete mixture can serve as a heating system, simply by applying electricity to the carbon-infused concrete.
In summary, this innovative supercapacitor technology not only represents an exciting leap forward in the world of renewable energy but also highlights the potential of concrete as a key player in the ongoing energy transition.
By Impact Lab