Artistic illustration of a coin cell with an electrode of copper (left) with a black nanochain structure that scientists have discovered could boost the battery’s capacity and speed up charging. Source: Purdue University illustration/Henry Hamann
How the battery of your computer or phone lasts depends on the number of lithium ions contained in the battery’s negative electrode. If the battery is depleted of the ions, it won’t create an electrical current that can operate a device and eventually will fail.
Materials with a greater lithium-ion storage capacity are too heavy or have the wrong shape for replacing graphite, the electrode substance currently used in batteries.
Purdue University scientists and engineers have proposed a possible way to use these materials modified into a different electrode design that will permit them to prolong the life of batteries and make them more durable and reduce the time it takes to charge.
The research, which is featured on the cover of September’s edition of Applied Nano Materials, created the net-like structure known as”nanochain. “nanochain,” of antimony, a metalloid known to increase the charge capacity of lithium-ion batteries.
Researchers have compared the nanochain electrodes with graphite electrodes. They found that even when the coin cell batteries equipped with nanochain electrodes were recharged for 30 min, they had twice the lithium-ion capacity in the charge discharging cycle of 100.
A few commercial batteries have carbon-metal-based composites, similar to negative electrodes made of antimony. However, the composite material tends to expand as much as three times its size lithium ions, leading to a safety risk as the battery is charged.
“You should be able to accommodate this kind of expansion into your smartphone’s battery. So you’re not carrying an unsafe device,” said Vilas Pol, a Purdue Associate Professor of Chemical Engineering.
A new technique could enable more efficient materials to form electrodes for batteries by making the nanochain, the black material that covers the copper electrode in the coin cell. Source: Purdue University image/Kayla Wiles
Using chemical substances – such as a reducer and nucleating agent Purdue researchers linked the antimony particles in the shape of a nanochain that could allow for the necessary expansion. The specific reducing agent that the team utilized, ammonia-borane is responsible for forming the empty spaces – pores within the nanochain, which can accommodate expansion and reduce the failure of electrodes.
The researchers applied ammonia-borane to various antimony compounds and discovered that only antimony-chloride created the nanochain structure.
“Our technique to make the nanoparticles regularly provides the string structures,” explained P. V. Ramachandran, who is a professor of organic chemical chemistry at Purdue.
The nanochain will keep the lithium-ions capacity for 100 charging-discharging cycles. “There’s primarily no change from routine 1 to routine 100, so we have no reason to think that routine 102 won’t be the same,” Pol stated.
Henry Hamann, a chemistry graduate student at Purdue, has synthesized an antimony-based nanochain. Jassie Rodriguez, a Purdue Chemical Engineering postdoctoral fellow, evaluated the electrochemical battery’s performance.
The electrode design can scale up to larger batteries, the researchers claim. The team will try the design on pouch cell batteries later.