Lithium ion batteries are the current standard power source for most electronic devices. Positively-charged lithium ions move from the cathode, through an electrolyte to the anode when the lithium-ion battery is charging. When the battery is connected to a device, the ions perform the same process in reverse.
Seeing the cost of Lithium, scientists are developing sodium ion batteries as a cost-effective alternative for rechargeable power source.
In both cases, the choice of electrode material is crucial: it has a significant influence on a battery's energy capacity and its overall lifetime. Sodium ion batteries optimized different materials that are good electrodes in lithium ion batteries.
It is still not fully understood yet the storage mechanism in the emerging class of anodes in the sodium ion batteries but we know these materials are attractive anodes due mainly to their ability to minimize volume changes during operation.
A two-dimensional anodes process for sodium ion batteries made from tin selenide1 was developed by scientists. A combination of experimental and computational studies to unlock the mechanism by which they store sodium ions.
The production process involves complex chemical reactions performed at high temperatures that can require toxic materials in which the Tin selenide has been synthesized.
The team tried a simpler hydrothermal method that uses a solution of sodium hydrogen selenide as a safe and stable source of selenium. They mixed this with tin and selenium and heated it in an oven at 180 degrees Celsius for 24 hours to produce nanosheets.
The study shows that during battery operation, the tin selenide stores sodium ions by a two-step process involving both conversion and alloying reactions. The high capacity is achieved by using SnSe2 anodes which lead to this dual mechanism. The results of the new synthesis process is noted to be the highest energy density (515 milliamper-hours/gram) of any transition metal selenide which is after 500 life cycles.