The photo is sourced from rscf.ru
Each battery has two electrodes (current-carrying elements) inside – a cathode and an anode. Cathode – an electrode with a positive charge – consists of the layer with the mix of lithium oxide and transition metals, and anode (a negatively charged electrode) – of the carbon layer on the copper foil. The electrodes are divided by a porous spacer impregnated with electrolytic fluid – a mix of organic solvents and salts. If this spacer is damaged, the elements inside the battery start to react with each other emitting heat, and within seconds the battery warms up to almost 600 degrees Celsius. Ignition or explosion may be a result.
To solve this problem the SPSU scientists created a polymer consisting of organic chains containing atoms of nickel. The authors put a thin layer of this new polymer between the aluminum foil sheets carrying electric current and the cathode. This allowed for excluding the possibility of ignition or explosion, because this polymer stops carrying current in the electric circuit in case the battery is charged from the socket with the voltage higher than required. This effect also allows for short circuit prevention: the polymer stops carrying current when the battery is discharged below a certain limit.
The scientists performed stress tests using small batteries (like a coin) used in smart watches. The tests showed that in case the voltage went beyond the range of 2.8 V (batteries stop discharging at this threshold) and 5 V (standard voltage in the charger for smartphones), the protection was 100% effective. At the same time, the polymer layer did not affect the capacity and productivity of the battery, or reduced them by no more than 10%.
“Today we are working to scale-up the production of lithium-ion batteries with our polymer layer, and negotiations with the investors are underway. So far, we have performed the stress tests only for small batteries, but in future we intend to test our technology for big ones, e.g., used in telephones, and after that we can launch the production of new safer batteries”, the Russian Science Foundation is citing Oleg Levin, one of the authors of the study, doctor of chemistry.
