“While lithium-ion batteries, widely used in mobile devices from cell phones to laptops, have one of the longest lifespans of commercial batteries today, they also have been behind a number of recent meltdowns and fires due to short-circuiting in mobile devices. In hopes of preventing more of these hazardous malfunctions researchers at Drexel University have developed a recipe that can turn electrolyte solution — a key component of most batteries — into a safeguard against the chemical process that leads to battery-related disasters.
Yury Gogotsi, PhD, Distinguished University and Bach professor in the College of Engineering, and his research team from the Department of Materials Science and Engineering, recently published their work — entitled “Nanodiamonds Suppress Growth of Lithium Dendrites” — in the journal Nature Communications. In it, they describe a process by which nanodiamonds — tiny diamond particles 10,000 times smaller than the diameter of a hair — curtail the electrochemical deposition, called plating, that can lead to hazardous short-circuiting of lithium ion batteries.
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 minimize 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 breakthrough made by Gogotsi’s team means that a great increase in energy storage is possible because dendrite formation can be eliminated in pure lithium electrodes.”