doi:10.1038/nindia.2015.93 Published online 14 July 2015
Indian scientists have found a radically new way to make a battery that is driven by light from the sun or from a lamp. The "photo battery" as it has been named can run small electronics and recharge without an outside power source1.
Metal-ion batteries such as those based on lithium (Li), which currently dominate the battery market, take a long time to charge, can overheat and catch fire if they are defective or damaged. Further, the usage of Li-based batteries pollute the ecosystem severely.
A research team led by Musthafa Ottakam Thotiyl at the Indian Institute of Science Education and Research (IISER) in Pune decided to address these flaws in a unique way. Instead of Li, their eco-friendly photo battery uses Titanium Nitride (TiN) as photoanode allowing the battery to charge itself using solar or artificial light.
Additionally, being more stable than traditional anode materials, TiN is less likely to overheat and catch fire. "In essence, this combines the light harvesting component and energy storing component in the same device which is more economical and practical," Musthafa said.
The current delivered by the photo battery was negligible in the dark but shot up on shining light, "confirming that the battery chemistry is light driven", the researchers said. For a single cell (in ambient light) the obtained open circuit voltage was about 1.1 Volt, and "under normal indoor lighting, the battery recharged in just 30 seconds getting ready for another burst of power," Musthafa told Nature India. "It was able to discharge enough current to illuminate a light emitting diode (LED) or run a small fan."
The researchers admit that though their battery is not yet strong enough to run commercially available devices such as smart phones, "the design is a promising first step" toward a more sustainable and safer battery technology. "This sustainable device addresses critical issues such as longer charging time, requirement of charging voltage and higher self-discharge rate often encountered in typical energy storage devices."
"At the moment we are trying to increase the light absorbing capability of photo anode, and increase the overall efficiency of the device so that it will be able to power more power hungry devices such as mobile phones and laptops," Musthafa said.
Since the new battery is driven by light, can it be used at night? "No problem," says the report. "Since the battery works in ambient light, it may be able to produce power in the presence of street light, household lighting or indoor lighting."
Musthafa's team included scientists from National Chemical Laboratory, also in Pune, and from the Acharya Institute of Technology, Bengaluru.