Tech Insights

Giving Batteries a Shot: Toyota’s Battery Revival Technology

April 10, 2024 by Darshil Patel

Capacity-recovery technology from Toyota may be the quickest way to revive lithium-ion batteries without dismantling them.

The need for higher range, faster charging, and improved battery life in lithium-ion batteries is growing with the increased demand for electric vehicles (EVs) and consumer electronics. This push is leading to research and development in electrode materials, manufacturing capabilities, and cell design innovations.

A major concern related to battery sustainability is degradation over time. Researchers are developing electrolyte additives to improve the stability of the electrode materials and slow down the degradation process. Furthermore, machine learning algorithms can identify early signs of degradation and predict battery life for the potential to extend its life.

 

Used electric vehicle batteries.

Used electric vehicle batteries. Image used courtesy of Adobe Stock

 

Another way to address this issue is to recycle spent batteries. However, this process is time and energy-intensive. 

Toyota researchers introduced a unique solution to shorten the recycling interval and increase battery life by injecting reagents. Their recovery reagent can regenerate capacity-degraded batteries even in high-capacity batteries, providing a new alternative for circular battery systems.

 

Capacity Regeneration for Lithium-Ion Batteries

During discharging, ions in a lithium-ion battery travel from the anode (negative electrode) to the cathode (positive electrode). This flow powers electronics. The flow reverses when the battery charges. Over time, chemical reactions and physical changes can reduce the battery’s capacity. If battery deterioration is due to chemical reactions or loss of carrier ions, some techniques can potentially improve their performance. One method is regeneration, involving controlled discharge and recharge cycles to help balance the internal chemistry and improve how efficiently ions flow.

Toyota researchers presented a single-step process of injecting reagents to counter ion loss. During battery charging, irreversible decomposition with electrolyte at the anode interface consumes positive lithium ions, forming a solid-electrolyte interface (SEI) film. The SEI formation is responsible for the loss of carrier ions. Researchers devised a way to provide positive lithium ions to the cathode and electrons through a chemical reduction reaction using lithium naphthalenide as a reducing reagent.

 

Illustration of the battery recovery process

Illustration of the battery recovery process. Image Courtesy of Toyota

 

The recovery reagent was able to reverse the degradation of the battery and restore up to 80% of its original capacity. The researchers also mentioned the recovered battery maintained its performance for 100 charging and discharging cycles. They achieved this by controlling the reaction potential of the recovery reagent through the dielectric effect. Moreover, they reported the naphthalenide compound is suitable for controlling the dielectric constant and processing large volumes for degraded batteries.

Toyota scientists tested their method for up to four Ah-class practical batteries. They believe their method could save money and resources, as lithium-ion batteries contain valuable materials like cobalt and nickel. However, this method is not suitable for batteries with damaged electrodes or any deterioration. Diagnosis of the battery state is also required before injecting the reagent.