A group of scientists working at the Pacific Northwest National Laboratory of Department of Energy and visiting researchers from the China located Wuhan University, have formulated a technique that betters the present electrical capacity and recharging life-span of the sodium ion rechargeable batteries.
The crystalline, uniform nanostructure of heat-treated manganese oxide provides pathways in which sodium ions can flow, improving the performance of the manganese oxide electrodes
The new invention is anticipated offer a cost-effective alternative for large-level usages such as storing the power over the electrical grid.
The commonly used lithium ion rechargeable batteries though performed well were considered expensive to use in the grids due to large quantity requirement. They could not replace the lithium ions with cheaper sodium ions because of its bigger size but they tried electrodes in lithium batteries made of manganese oxide using nano technology.
During the research, the team combined two dissimilar types of manganese oxide building blocks, out of which one block had atoms that arranged themselves in pyramids and the other block atoms formed an octahedron and a structure resembling a diamond from two pyramids clung together at their bases. They anticipated the end material to possess large S-shaped tunnels and smaller five-sided tunnels to allow free flow of ions.
After mixing, the team treated the materials with 450 to 900°C temperatures, studied them to understand which treatment performed better. The results of electron microscope proved that the varied temperatures produced different quality materials. They found that manganese oxide when treated at 750°C produces best form of crystals. At low level temperatures the crystals appeared flakey and at higher level they became flat plates of large size.
The researchers calculated the peak capability at 128 mAh/g of electrode material as observational battery cell discharged. The material performed well during charging and the discharging cycles.
The researchers also found that the cells held less quantity of electricity when charged faster showing the problem with sodium ions in getting disseminated into the manganese oxide thus limiting the battery cell’s capability. To overcome the problem they are planning to make even smaller nano-wires to quicken the charging and discharging activities. They believe that it will work ably with grid batteries, which need quicker charging capabilities to collect most of the renewable energy generated and discharge the collected energy quickly to meet the shooting consumer demands.
Source: http://www.pnl.gov