Korean engineers have created novel lithium ion batteries made of a porous solid material that are less likely to overheat.
The researchers said they took a completely different approach to battery-making than that used in current devices relying on intercalated lithium. Instead, the new batteries are made of pumpkin-shaped molecules of a material known as cucurbituril, or CB, which are organized in a honeycomb-like structure.
“It is possible for this lithium ion conduction following porous CB to be safer than existing solid lithium, electrolyte-based, organic-molecular porous materials utilizing the simple soaking method,” said Kimoon Kim, researcher at South Korea’s Pohang University.
The physical structure of the porous CB enables the lithium ions inside the battery to diffuse more freely than in conventional Li-ion batteries. The new technology also works without the so-called separators.
In tests, the porous CB solid electrolytes showed impressive lithium ion conductivity.
The researchers found the novel batteries have the lithium transference number at 0.7 to 0.8 while conventional Li-ion batteries offer only 0.2 to 0.5.
During testing, the new batteries were subjected to extreme temperatures of up to 99.85°C, well above the 80°C limit for conventional lithium ion batteries. The researchers ran the batteries through several cycles of temperature changes between 99.85 °C and 24.85 °C, after which the batteries showed no thermal runaway and hardly any change in conductivity.
Lithium-ion batteries power all modern electronic devices including computers, smartphones and tablets, as well as electric vehicles. With the increasing power consumption of these systems, the demands placed on the batteries are constantly growing and the technology is gradually reaching its limits.
Since 2002 there have been over 40 recalls in the US alone due to fire or explosion risk from lithium-ion batteries used in consumer electronic devices. Such incidents frequently happen as a result of overheating, something the novel porous material may help to solve.