吉武秀哉

Abstract:

Among the relaxation behaviors during charging of lithium-ion batteries, this time we will speculate on the relaxation behaviors that involve lithium precipitation.

At the Iide Battery Research Institute, we tear down various types of electric vehicles and analyze the vehicle, motor, inverter, battery pack, BMS, cells, etc.

Since 2012, we have already performed teardowns of more than 60 vehicles, and from the information obtained, we support the development of battery materials by "predicting future trends in EV technology" and "providing solutions to current issues".

While EVs have many advantages compared to engine vehicles, such as "torque", "quietness", and "acceleration", the long "charging time" has been an issue, but recently, batteries that can be quickly charged have begun to be installed in electric vehicles.

We used two cylindrical batteries (46XXX) that can be quickly charged (<3.0C) that began to be installed in EVs in 2023, and conducted tests in which they were charged at a low temperature (253 K), allowed a relaxation time at a specified temperature (318 K), and then discharged at the same temperature (318 K).

Analysis of the graphite stage structure using small-angle neutron scattering analysis (SANS) showed that although the fast-charging battery had a large amount of lithium plating, the discharge capacity immediately after was 94% or more.

This suggests that it may be possible to provide a battery that combines the performance of a "lithium-ion battery" and a "lithium metal battery" by effectively controlling the lithium plating during the charging process (not meaning to eliminate plating).

We were able to clarify not only the experiment to understand the Li+ diffusion effect in the graphite anode, but also the behavior of lithium metal (lithium plating) being doped into the graphite anode.

SIKA will be a very important tool in the future development of graphite anodes for fast charging.

 Back