Conductive Carbon Coated Polymer For High Temperature Lithium-Ion Battery Shutdown

This technology relates to a lithium-ion battery with an improved electrode with automatic shutdown function. The technology owner has developed a method to generate a 3D printing ink to deposit a layer of thermal sensitive polymer, which can be implemented into the traditional battery production process to solve the thermal failure of the lithium ion battery. The technology owner is looking for potential licensees to commercialise this technology.

The lithium ion battery comprises a first electrode with a second electrode, and a shutdown polymer additive being provided on an outer surface of the first electrode. The shutdown polymer additive comprises at least two polyethylene (PE) layers, each PE layer comprising a plurality of PE microspheres. Each PE microsphere is wrapped with carbon nanotubes (CNT). The PE microspheres interconnect with each other such that the carbon nanotubes form a conductive network. The PE layers are provided at predetermined areas of the outer surface of the first electrode. In the testing process, the battery can function as a normal battery. When the working temperature is above 90 degree, the temperature sensitive polymer will melt within 60 seconds. The polymer will block the pores of the electrode and the battery will stop charging and discharging.

The advantages of this technology are:

1. The PE layers do not essentially affect performance of the battery while preventing the battery from reaching the battery thermal runaway temperature.
2. The PE layers can be separated from each other by a predetermined distance. The predetermined distance allows, in the shutdown mode, the PE layers to be placed apart and yet close enough such that the molten PE layers can extend to form one insulating film.
3. 3D printing technology can modify any electrodes to enable the automatic shutdown function.
4.  Any part of the battery can be modified, such as anode, cathode and membrane. 

• The automatic shutdown function can be implemented in all the different types of batteries.
• Portable electronics, electric vehicles and military applications.

Global lithium ion battery market is valued about USD 43.4 billion in 2019 and is anticipated to grow steadily at more than 16% from 2020-2026. The lithium ion battery is the leading choice of electrical energy storage for small portable devices and it has a great potential for large-scale implementation in electric vehicles. However, safety of the lithium ion battery is a key concern.

The lithium ion battery is susceptible to thermal failure, which can be triggered by overheating, overcharging, or short-circuiting of the battery. Though commercial lithium-ion batteries include several safety mechanisms, the internal shutdown separators are prone to shrinkage, resulting in short-circuiting of the electrodes, and the external safety devices may not be able to respond in time to thermal runaway events, which can occur as soon as a minute, after a short circuit of the battery.

• A shorter shutdown time when thermal runaway is about to occur, while also providing little impact on battery performance.
• The deposition of such polymer layer can enable the battery to automatically shutdown the coin cell within 60 s at a temperature above 90 degrees.
• The detected performance impact on the cell is below 5%.
• Deposition of shutdown layers to the separator or electrode can be achieved within 15 mins.