A novel self-charging power cell that has the ability to convert and store energy has been developed by researchers at the Georgia Institute of Technology. The hybrid generator-storage cell directly converts mechanical energy to chemical energy. When compared to other systems that use separate batteries and generators, the new cell makes better utilization of mechanical energy.
Components of a new self-charging piezoelectric power cell are shown in this photo. The clear disc in the center is the piezoelectric film that serves as a charge pump for lithium ions.
Normally, generation of electricity and its storage are considered as separate activities and are performed in separate units. The new power cell contains both charge conversion and storage. Titanium dioxide nanotubes that have been grown upon a titanium film are used as the anode, while lithium-cobalt oxide is used as the cathode in the power cell. A polyvinylidene fluoride (PVDF) film membrane is used to separate the electrodes.
A piezoelectric potential is generated by the PVDF film when the power cell undergoes mechanical compression. This potential functions as a charge pump and drives lithium ions to the anode side where it is stored as lithium-titanium oxide. Charging takes place in cycles and gets completed when lithium-cobalt oxide gets oxidized to Li1-xCoO2 at the cathode and titanium dioxide gets oxidized to LixTiO2 at the anode. The cycle repeats when the power cell is compressed again. The compression required may be generated even when a person walks.
On connecting an experimental electrical load, the researchers found that the power cell demonstrated a storage capacity of 0.036 mAh. Lithium ions flowed back to the cathode while electrons flowed to the load. The researcher’s stated that improved packaging materials will increase the power stored by the cell.
The study was conducted by Professor Zhong Lin Wang, Xinyu Xue, Wenxi Guo, Sihong Wang, and Yan Zhang and it has been reported in the journal Nano Letters.