Army scientists are making lighter, more powerful, and more durable batteries to help soldiers lighten their loads on the battlefield.
Lithium ion batteries and battery chemical properties are studied and tested at the Army Research Lab, in Adelphi, Maryland.
Tests are perform on batteries that are like those that power watches; they’re called “button cells.”
The sides of each cell are called electrodes. The side with a subtraction symbol is called an anode, and the side with the addition symbol is called the cathode. Electrolytes in between help move lithium ions to the electrodes, so electrical current can circulate out of the battery to power a device.
The Chief of the Electrochemistry Branch of Power and Energy Division at the Army Research Lab, Cynthia Lundgren, develops electrodes out of new materials that make a battery lighter by boosting its voltage.
“If we could raise the voltage of a single cell — energy density is a direct function of the voltage — we could make the battery lighter,” Dr. Lundgren said. “The problem is, as you go up in voltage, the electrode becomes much more energetic, and so it reacts with the electrolyte.”
The more a battery’s electrode reacts with its electrolytes, the electrolytes ability to transfer lithium ions to produce electrical current deteriorates. That means that every time rechargeable batteries are charged they are less able to hold that charge. Battery life is shortened, and a soldier has to carry more batteries that increases her load.
Lundgren’s team produced HFiPP or “tris (hexafluoroisopropyl) phosphate” that is combined with a cell’s electrolytes, so a battery can keep its charge.
“It’s a corrosion inhibitor,” Dr. Lundgren said. “You just add it to the electrolyte that any manufacturer would put in. It’s a little bit of pixie dust.”
Army chemist, Jan Allen, made a iron-doped lithium cobalt phosphate cathode (LiCoPO4) at 4.9V.
Although the LiCoPO4 cathode reacts highly with the electrolyte (due to its high voltage), once the HFiPP is combined with the electrolyte users can have higher powered batteries that can be charged more times without losing battery life and corrosion.