Indian Researchers Achieve Major Leap in Clean Energy with Development of Self-Charging Solar Supercapacitor

Indian scientists have developed a self-charging energy storage device powered by sunlight, marking a significant breakthrough in clean and sustainable energy technology. The innovative device, known as a photo-capacitor, can simultaneously harvest and store solar energy within a single integrated system, paving the way for efficient, low-cost, and eco-friendly power solutions for portable, wearable, and off-grid applications.

The technology has been developed by researchers at the Centre for Nano and Soft Matter Sciences (CeNS), Bengaluru, an autonomous institute under the Department of Science and Technology (DST), Government of India. The photo-rechargeable supercapacitor eliminates the need for separate solar panels and energy storage units, along with additional power management electronics, thereby simplifying system design, reducing energy losses, lowering costs, and minimizing device footprint.

Under the guidance of Dr Kavita Pandey, the research team developed the device using binder-free nickel-cobalt oxide (NiCo₂O₄) nanowires grown uniformly on nickel foam through a simple in-situ hydrothermal process. The nanowires form a highly porous and conductive three-dimensional network that efficiently absorbs sunlight while simultaneously storing electrical charge, enabling the material to function both as a solar energy harvester and a supercapacitor electrode.

Performance tests demonstrated a 54% increase in capacitance under illumination, with values rising from 570 to 880 mF cm⁻² at a current density of 15 mA cm⁻². The electrode also exhibited excellent durability, retaining 85% of its original capacity even after 10,000 charge-discharge cycles, indicating long-term operational stability.

To assess real-world applicability, the researchers fabricated an asymmetric photo-supercapacitor using activated carbon as the negative electrode and NiCo₂O₄ nanowires as the positive electrode. The device delivered a stable output voltage of 1.2 volts and maintained 88% capacitance retention after 1,000 photo-charging cycles, operating efficiently under a wide range of lighting conditions, from indoor illumination to high-intensity sunlight.

The integrated architecture enables the development of self-charging power systems capable of operating in remote and off-grid regions, significantly reducing reliance on fossil fuels and conventional batteries. Theoretical studies conducted alongside experimental validation revealed that nickel substitution in the cobalt oxide framework narrows the material’s band gap and induces half-metallic behavior, enabling faster charge transport and enhanced electrical conductivity.

The findings, published in the journal Sustainable Energy & Fuels by the Royal Society of Chemistry, highlight a paradigm shift in renewable energy storage and underscore the potential of nanostructured materials for light-responsive energy systems. With further development, such technologies could play a vital role in advancing India’s clean energy ambitions and driving global innovation in sustainable power solutions.