BQ40Z80: SoC accuracy at low temperatures

Tool/software:

I made a pack with BQ40z80 and checked the SoC accuracy during discharge.

As a result, I confirmed that the accuracy of discharge SoC differed by more than 10% at 0℃, -10℃, and -20℃.

Test results

1. 0℃ SoC test results (BQ vs. calculated results)

2. -10℃ SoC test results (BQ vs. calculated results)

3. -20℃ SoC test results (BQ vs. calculated results)

So I have the following questions. Please answer them.

1. Why does the discharge SoC differ so much as the temperature decreases?
2. How can I solve this problem?
3. If there is a way, please let me know.