Toyota Motor Corporation is working on a new technology which aims to increase performance and longevity of electric car batteries. According to the company, it has developed a certain method for observing the behaviour of lithium ion in an electrolyte when a Li-ion battery charges and discharges.
It believes with the help of this method, it is possible to observe in real-time, the deviation of Li-ions - one of the causes of deterioration in the performance of Li-ion batteries.
Li-ion batteries use a metal oxide in the cathode, a carbon material in the anode, and an organic electrolyte for the electrolyte. Lithium ions flow in the electrolyte from the cathode to the anode when the battery is charging, and from the anode to the cathode when the battery is discharging, which results in an electric current flow.
It has been known that Li-ion deviation occurs in the electrodes and electrolyte as a result of charging and discharging, and such deviation has been believed to limit the usage area of batteries, which is one factor that reduces the area in which the maximum performance of the battery can be achieved.
After this observation method, Toyota thought in place of the electrolyte with phosphorus that is used in many Li-ion batteries, a new electrolyte with heavy elements is being utilised instead, thus replacing the phosphorous-containing ions that the Li-ions bind to as they move in the electrolyte with heavy element-containing ions.
Heavy elements transmit less of the X-rays than phosphorous, and the shadows on the images taken after the X-rays pass through are darker. By observing the behaviour of the heavy elements, it is possible to observe the deviation behaviour of the Li-ions which are bound to them in the electrolyte.
This observational method was jointly developed by Toyota Central R&D Labs, Nippon Soken, and four universities.