Tiny diamonds can prevent fires in mobile phone batteries
26 Aug 2017, 17:06
New York: Researchers have found that nanodiamonds -- tiny diamond particles 10,000 times smaller than the diameter of a hair - can prevent short-circuits and fires in lithium batteries widely used in mobile devices from cell phones to laptops.
The new process can turn electrolyte solution -- a key component of most batteries -- into a safeguard against the chemical process that leads to battery-related disasters.
In the study, published in the journal Nature Communications, the researchers described a process by which nanodiamonds curtail the electrochemical deposition, called plating, that can lead to hazardous short-circuiting of lithium ion batteries.
"We anticipate the first use of our proposed technology will be in less critical applications -- not in cell phones or car batteries," said Yury Gogotsi, Professor at Drexel University in Philadelphia, Pennsylvania, US.
"To ensure safety, additives to electrolytes, such as nanodiamonds, need to be combined with other precautions, such as using non-flammable electrolytes, safer electrode materials and stronger separators," Gogotsi added.
As batteries are used and charged, the electrochemical reaction results in the movement of ions between the two electrodes of a battery, which is the essence of an electrical current.
Over time, this repositioning of ions can create tendril-like buildups -- almost like stalactites forming inside a cave.
These battery buildups, called dendrites, are one of the main causes of lithium battery malfunction.
As dendrites form inside the battery over time, they can reach the point where they push through the separator, a porous polymer film that prevents the positively charged part of a battery from touching the negatively charged part.
When the separator is breached, a short-circuit can occur, which can also lead to a fire since the electrolyte solution in most lithium-ion batteries is highly flammable.
To avoid dendrite formation and minimise the probability of fire, current battery designs include one electrode made of graphite filled with lithium instead of pure lithium.
The use of graphite as the host for lithium prevents the formation of dendrites. But lithium intercalated graphite also stores about 10 times less energy than pure lithium.
The new study showed that mixing nanodiamonds into the electrolyte solution of a lithium ion battery slows dendrite formation to nil through 100 charge-discharge cycles.
The finding means that a great increase in energy storage is possible because dendrite formation can be eliminated in pure lithium electrodes.
The discovery is just the beginning of a process that could eventually see electrolyte additives, like nanodiamonds, widely used to produce safe lithium batteries with a high energy density, Gogotsi noted.