RMML Co.,Ltd.

Evaluation for batteries and magnetic materials

We conduct evaluations for cells and manufactured batteries by Cole-Cole plot.
In addition, we evaluate magnetic materials about coercive force and the saturated magnetization by VSM.

Battery evaluation

When we analyze internal resistance, we use Cole-Cole plot fitting to know whether the charge transfer resistance is anode or cathode, or it is caused by an electrolyte.

It is known that resistance differs between Ni battery and Li ion battery, and because the resistance is higher in Li ion one, the quantity of heat generated by Li is bigger than Ni

We only have one simple charge/discharge device, so we cannot evaluate charge/discharge capacity. You need to analyze totally with charge/discharge device changing C rate, and with pulse electric current. So please note that what we can do is only evaluating them in quality control.

Evaluation for the magnetic material

Basically, we use evaluation VSM in the direct current magnetic field in cooperation with other companies. If it's interchange magnetic field, the evaluation equipment and the evaluation methods vary according to frequency band, which is very difficult.
Therefore, what we can evaluate is saturated magnetization, residual magnetization and coercive force using VSM.

The characteristic analysis of battery
The result of fitting

Model 1

The characteristic analysis of battery. The result of fitting
One example of the unified equivalent circuit to evaluate the battery material and the result of fitting

Model 2

One example of the unified equivalent circuit to evaluate the battery material and the result of fitting

The fitting succeeded within 5% error precision. After that, we carried out data analysis in a standard with this equivalent circuit.

Direct current resistance R1:resistance
Anode Zw: warburg impedance
Inductance L1:
Anode C2:condenser
Cathode C1:condenser
Anode charge transfer resistance R3:resistance
Cathode charge transfer resistance R2:resistance
Anode CPE:constant phase element


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