Battery pack and power consuming device

1. A battery pack, comprising a battery pack case and a plurality of battery cells accommodated in the battery pack case, wherein

an inner space of the battery pack case may be divided into a first region located at the center and a second region enclosing the first region; and

the plurality of battery cells comprise: at least one first battery cell disposed in the first region; and at least one second battery cell disposed in the second region, wherein

an internal resistance of the first battery cell and an internal resistance of the second battery cell increase with the decrease of a temperature, and when the internal resistance of the first battery cell and the internal resistance of the second battery cell are respectively R A1 and R B1 at 25° C. and are respectively R A2 and R B2 at −20° C., 1≤R B1 /R A1 ≤2 and 1.2≤R B2 /R A2 ≤2.5, optionally, 1.3≤R B1 /R A1 ≤1.6 and 1.3≤R B2 /R A2 ≤1.7.

2. The battery pack according to claim 1 , wherein

ΔR A ≤ΔR B ≤7ΔR A , wherein ΔR A =R A2 −R A1 and ΔR B =R B2 −R B1 .

3. The battery pack according to claim 1 , wherein

0.1 mΩ≤R A1 ≤5 mΩ and 0.1 mΩ≤R B1 5 mΩ.

4. The battery pack according to claim 1 , wherein

1 mΩ≤R A2 ≤50 mΩ and 1 mΩ≤R B2 ≤50 mΩ.

5. The battery pack according to claim 1 , wherein

a ratio of a volume of the first region to a total volume of the first region and the second region ranges from 10% to 60%.

6. The battery pack according to claim 1 , wherein

the first battery cell and the second battery cell comprise one or two or more of lithium iron phosphate batteries, ternary batteries, and sodium-ion batteries.

7. The battery pack according to claim 1 , wherein

a positive electrode plate of each of the first battery cell and the second battery cell contains a negative temperature coefficient material, and

the content of the negative temperature coefficient material in the positive electrode plate of the second battery cell is higher than that of the negative temperature coefficient material in the positive electrode plate of the first battery cell,

wherein the content of the negative temperature coefficient material in the positive electrode plate=the mass of the negative temperature coefficient material in the positive electrode plate/(the mass of the positive electrode plate−the mass of a positive electrode current collector)×100%.

8. The battery pack according to claim 7 , wherein

the negative temperature coefficient material is doped in a positive electrode active material layer, or prepared into a coating to coat the positive electrode current collector or a surface of the positive electrode plate.

9. The battery pack according to claim 7 , wherein

the content of the negative temperature coefficient material in the positive electrode plate of the first battery cell and the content b of the negative temperature coefficient material in the positive electrode plate of the second battery cell respectively meet 0≤a≤5% and 5%≤b≤15%.

10. The battery pack according to claim 7 , wherein

the negative temperature coefficient material is a compound composed of one or more metallic elements selected from Ti, V, Cr, Fe, Co, Ni, Mn, Cu, Sn, Y, Mo, Zr, W, La, Nd, and Yb and one or two non-metallic elements selected from P, F, C, O, and S.

11. The battery pack according to claim 10 , wherein

the negative temperature coefficient material is Mn 1.5 Co 1.2 Ni 0.3 O 4 , Fe 0.2 Mn 2.2 Ni 0.6 O 4 , NiMn 1.6 Mg 0.4 O 4 , Mn 1.4 Co 0.9 Ni 0.7 O 4 , or Mn 1.6 Co 0.4 CuO 4 doped with 0.1RuO 2 .

12. The battery pack according to claim 1 , wherein

the number of first battery cells in the first region accounts for 50% or more.

13. The battery pack according to claim 1 , wherein

the number of second battery cells in the second region accounts for 50% or more.

14. A power consuming device comprising the battery pack according to claim 1 .