Indian Scientists Created Sunlight-Powered Self-Charging Photo-Capacitor

Indian Scientists Created Sunlight-Powered Self-Charging Photo-Capacitor

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Recently, Indian scientists have created a sunlight-powered self-charging supercapacitor called a photo-capacitor that can both capture and store solar energy in one device, avoiding separate solar panels and batteries.

India’s Sunlight-Powered Self-Charging Photo-Capacitor

• About: A Sunlight-Powered Self-Charging Photo-Capacitor is an integrated energy device that can simultaneously capture sunlight and store electrical energy in a single unit, eliminating the need for separate solar panels and batteries. It merges solar energy harvesting and supercapacitor storage functions into one system.
• Developed By: This innovation has been developed by researchers at the Centre for Nano and Soft Matter Sciences (CeNS), which is an autonomous institute under the Department of Science and Technology (DST). The research has been guided and led by Dr. Kavita Pandey and her team.
• Objectives: The primary objectives of developing the photo-capacitor are:

• To integrate solar energy harvesting and storage into one device, thereby eliminating separate components like conventional solar panels and batteries.
• To reduce energy losses associated with power conversion and management in hybrid systems.
• To achieve efficient and self-sustaining power solutions, especially suitable for portable electronics.
• To support India’s clean energy and sustainable technology goals by advancing renewable energy storage capacity.

• Components: The key components and material features of the photo-capacitor include:

• NiCo₂O₄ Nanowire Electrodes: Binder-free nickel-cobalt oxide (NiCo₂O₄) nanowires grown uniformly on a nickel foam substrate via an in-situ hydrothermal process. 
• Positive and Negative Electrodes: In the complete device, NiCo₂O₄ nanowires act as the positive electrode, while activated carbon is used as the negative electrode in asymmetric configurations.
• Substrate and Current Collectors: Nickel foam serves as a mechanical support and current collector due to its conductivity and structural stability. 

• Working Process: The working process of the photo-capacitor is as follows: 

1. Sunlight Absorption: When sunlight hits the device, the NiCo₂O₄ nanowire network absorbs photons and generates electrical charge carriers. 
2. Photo-Generated Charge Transport: The nanowire structure, being highly conductive and porous, facilitates rapid transport of light-induced charges across the electrode surface.
3. Simultaneous Storage: Rather than first converting sunlight into electricity and then storing it (as in traditional systems), the device directly stores the generated charges in its supercapacitor structure while still exposed to light.
4. Output Generation: The photo-capacitor can deliver a stable output voltage (~1.2 V) and continues to hold charge efficiently even after repeated charging cycles. 

• Features: The sunlight-powered photo-capacitor demonstrates several significant features:
  • Enhanced Performance: Laboratory tests show a 54% increase in capacitance under illumination (from 570 to 880 mF cm⁻² at a 15 mA cm⁻² current density).
  • Long-Term Durability: The device maintains 85% capacitance retention after 10,000 charge discharge cycles and 88% after 1,000 photo-charging cycles.
  • Wide Light-Condition Operation: Performs efficiently under varying lighting conditions, from low indoor illumination to intense sunlight, proving practical for real-world applications.
  • Compact and Cost-Effective: The simplified architecture reduces the size, cost, and energy losses typically associated with hybrid energy systems.

Applications of Photo-Capacitor

• Portable and Wearable Electronics: The photo-capacitor is highly suitable for portable and wearable devices, such as smartwatches, fitness bands, small medical monitors, and handheld gadgets. By eliminating bulky separate solar panels and batteries, this tech could enable longer device uptime, higher mobility, and energy autonomy in daily use.
• Internet of Things (IoT) and Smart Sensors: In IoT ecosystems, where tiny devices often operate in remote locations, the integrated device can provide self-sustaining power for autonomous sensors and data loggers. Smart agriculture sensors, environmental monitors, smart city infrastructure, and industrial IoT nodes could continuously function without external power, significantly reducing maintenance.
• Off-Grid and Rural Applications: The photo-capacitor offers reliable off-grid power in areas lacking stable electricity infrastructure, especially in remote villages and disaster-affected zones. Its capacity to work under varied light—from indoor illumination to bright sunlight—supports lights, radios, low-power fans, and communication devices, helping meet energy needs.
• Emergency and Backup Power Systems: Due to its rapid charging ability and integrated storage, the device can serve as a backup power source during grid failures and emergencies. In critical situations, it can instantly supply power to emergency lighting, communication gear, and essential sensors, improving disaster response.

Significance for India’s Energy Transition

• The development of the photo‑capacitor directly supports India’s ambitious target of achieving 500 GW of non‑fossil fuel energy capacity by 2030, where solar is a cornerstone. 
• This aids India’s goals under the PM Surya Ghar Muft Bijli Yojana and other rooftop solar initiatives, providing energy resilience for remote and underserved communities.
• By embedding solar harvesting with storage, photo‑capacitors reduce dependence on imported lithium and critical minerals, addressing strategic vulnerabilities in the supply chain.
• This innovation aligns directly with India’s ambitious renewable energy targets, such as expanding solar capacity under the National Solar Mission and meeting commitments under the Nationally Determined Contributions (NDCs) to cut carbon emissions.
• This innovation aligns with India’s commitment to net‑zero emissions by 2070 by facilitating clean, reliable, and decentralised energy solutions, reducing fossil fuel reliance and advancing sustainability across sectors.