Charging Batteries with Indoor Lighting... Development of High-Efficiency Materials Signals Commercialization Prospects

Ulsan National Institute of Science and Technology Develops Indoor Lighting-Based Charging System
Energy Efficiency Breaks Previous 11.5% with 13.2%

Principle of Dye-Sensitized Solar Rechargeable Battery. Image provided by Ulsan National Institute of Science and Technology.

[Asia Economy Reporter Kim Bong-su] The era of energy recycling, where batteries are charged using discarded indoor lighting (light), is expected to come sooner. A new electrode material has been developed that significantly increases the charging efficiency of light illumination.

Ulsan National Institute of Science and Technology (UNIST) announced on the 25th that a research team led by Professors Song Hyun-gon and Kwon Tae-hyuk developed a battery system that raised the energy efficiency of indoor lighting to 13.2%. This far surpasses the previous highest record of 11.5% among developed photocharging systems.

The researchers improved charging efficiency by enabling lithium ions to be inserted faster into the electrode material lithium manganese oxide (LiMn2O4). By applying electrochemical stimulation to lithium manganese oxide, they aligned the particles in one direction and increased their size, allowing more lithium ions to be stored in the electrode more quickly. Transmission electron microscope images confirmed the improved particle alignment and size. Notably, the size of a single particle increased from the previous 26 nm (nanometers, 10^-9) to 34 nm.

The developed photocharging secondary battery system combines a dye-sensitized solar cell (generator) and a battery that stores the generated power. The more lithium ions stored in the battery electrode per unit time, the higher the charging efficiency. The research team previously developed such a system through prior research and recorded a high energy conversion and storage efficiency of 11.5%.

Dr. Lee Myung-hee of UNIST’s Department of Energy and Chemical Engineering explained, "Lithium manganese oxide has another reaction pathway for storing lithium ions besides the typical reactions in lithium-ion batteries, and by utilizing this, we were able to align the crystal structure." Research Assistant Professor Kim Byung-man of UNIST’s Department of Chemistry added, "In the reaction where additional lithium ions are inserted, the crystal structure changes from a cubic to a tetragonal structure. This change repeats during charging and discharging, which aligns the particles."

The research team also developed a battery system necessary for stable use even in the absence of light. Professor Kwon Tae-hyuk said, "Indoor lighting power generation is not only a technology that recycles electrical energy wasted by lighting but also has the advantage of no location, weather, or time constraints unlike solar power generation. When using the developed integrated system, electricity produced by indoor lighting can be used efficiently," expressing his expectations.

Professor Song Hyun-gon explained, "Simply applying electrochemical stimulation effectively improved the kinetic properties of the storage electrode material, increasing the battery’s charging efficiency. This material could also be applied to high-speed charging of lithium-ion batteries," he said.

This research is scheduled to be published as a cover paper in 'ACS Energy Letters,' a prestigious journal in the energy field.

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