Battery pack and power consuming device

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

in a top view, an inner space of the battery pack case is in a rectangular shape;

the inner space of the battery pack case includes a first area, a second area, a third area, and a fourth area, in the top view, the first area is located at a center of the rectangular shape of the inner space, the fourth area is located at four corners of the rectangular shape of the inner space, the third area is located on four sides of the rectangular shape of the inner space except the corners, and the second area is located between the first area and the third area;

a first battery cell is provided in the first area, a second battery cell is provided in the second area, a third battery cell is provided in the third area, and a fourth battery cell is provided in the fourth area;

in the top view, the second battery cell is not in contact with any inner surface of the battery pack case, the third battery cell is in contact with only one inner surface of the battery pack case, and the fourth battery cell is in contact with two inner surfaces of the battery pack case;

the first battery cell, the second battery cell, the third battery cell, and the fourth battery cell each have a first discharge voltage plateau and a second discharge voltage plateau, and an average discharge voltage in the first discharge voltage plateau is higher than an average discharge voltage in the second discharge voltage plateau; and

in each of the first battery cell, the second battery cell, the third battery cell, and the fourth battery cell, under a condition that a sum of a discharge capacity corresponding to the first discharge voltage plateau and a discharge capacity corresponding to the second discharge voltage plateau is 100%, a percentage of the discharge capacity corresponding to the second discharge voltage plateau of the fourth battery cell>a percentage of the discharge capacity corresponding to the second discharge voltage plateau of the third battery cell>a percentage of the discharge capacity corresponding to the second discharge voltage plateau of the second battery cell>a percentage of the discharge capacity corresponding to the second discharge voltage plateau of the first battery cell.

2. The battery pack according to claim 1 , wherein

in each of the first battery cell, the second battery cell, the third battery cell, and the fourth battery cell, a difference between a minimum discharge voltage in the first discharge voltage plateau and a maximum discharge voltage in the second discharge voltage plateau ranges from 0.25 V to 0.6 V.

3. The battery pack according to claim 1 , wherein

in the first battery cell, under a condition that the sum of the discharge capacity corresponding to the first discharge voltage plateau and the discharge capacity corresponding to the second discharge voltage plateau is 100%, the discharge capacity corresponding to the first discharge voltage plateau accounts for 91.8% to 99%, and the discharge capacity corresponding to the second discharge voltage plateau accounts for 1% to 8.2%.

4. The battery pack according to claim 1 , wherein

in the second battery cell, under a condition that the sum of the discharge capacity corresponding to the first discharge voltage plateau and the discharge capacity corresponding to the second discharge voltage plateau is 100%, the discharge capacity corresponding to the first discharge voltage plateau accounts for 75.7% to 96.8%, and the discharge capacity corresponding to the second discharge voltage plateau accounts for 3.2% to 24.3%.

5. The battery pack according to claim 1 , wherein

in the third battery cell, under a condition that the sum of the discharge capacity corresponding to the first discharge voltage plateau and the discharge capacity corresponding to the second discharge voltage plateau is 100%, the discharge capacity corresponding to the first discharge voltage plateau accounts for 60.2% to 89.4%, and the discharge capacity corresponding to the second discharge voltage plateau accounts for 10.6% to 39.8%.

6. The battery pack according to claim 1 , wherein

in the fourth battery cell, under a condition that the sum of the discharge capacity corresponding to the first discharge voltage plateau and the discharge capacity corresponding to the second discharge voltage plateau is 100%, the discharge capacity corresponding to the first discharge voltage plateau accounts for 52.5% to 80.3%, and the discharge capacity corresponding to the second discharge voltage plateau accounts for 19.7% to 47.5%.

7. The battery pack according to claim 1 , wherein

a positive electrode active material of each of the first battery cell, the second battery cell, the third battery cell, and the fourth battery cell is formed by mixing a first positive electrode active material with the first discharge voltage plateau and a second positive electrode active material with the second discharge voltage plateau.

8. The battery pack according to claim 7 , wherein

each of the first positive electrode active material and the second positive electrode active material comprises at least one selected from the group consisting of lithium nickelate, lithium cobalt oxide, lithium nickel manganese cobalt oxide, lithium nickel cobalt aluminium oxide, lithium iron phosphate, lithium manganese oxide, lithium titanate, and manganese dioxide.

9. The battery pack according to claim 7 , wherein

the first positive electrode active material is lithium nickel manganese cobalt oxide, and the second positive electrode active material is lithium iron phosphate;

or the first positive electrode active material is lithium nickel manganese cobalt oxide, and the second positive electrode active material is lithium manganese oxide or lithium titanate;

or the first positive electrode active material is lithium iron phosphate, and the second positive electrode active material is lithium manganese oxide or lithium titanate.

10. The battery pack according to claim 7 , wherein

under a condition that the first positive electrode active materials and the second positive electrode active materials in the first battery cell, the second battery cell, the third battery cell, and the fourth battery cell are both of the same type, respective mass percentages of the first positive electrode active materials in the positive electrode active materials of the first battery cell, the second battery cell, the third battery cell, and the fourth battery cell decrease successively, and respective mass percentages of the second positive electrode active materials in the positive electrode active materials of the first battery cell, the second battery cell, the third battery cell, and the fourth battery cell increase successively.

11. The battery pack according to claim 7 , wherein

in the first battery cell, under a condition that a total mass of the first positive electrode active material and the second positive electrode active material is 100%, a mass of the first positive electrode active material accounts for 92.5% to 97.5%, and a mass of the second positive electrode active material accounts for 2.5% to 7.5%.

12. The battery pack according to claim 7 , wherein

in the second battery cell, under a condition that a total mass of the first positive electrode active material and the second positive electrode active material is 100%, a mass of the first positive electrode active material accounts for 77.5% to 92.5%, and a mass of the second positive electrode active material accounts for 7.5% to 22.5%.

13. The battery pack according to claim 7 , wherein

in the third battery cell, under a condition that a total mass of the first positive electrode active material and the second positive electrode active material is 100%, a mass of the first positive electrode active material accounts for 62.5% to 77.5%, and a mass of the second positive electrode active material accounts for 22.5% to 37.5%.

14. The battery pack according to claim 7 , wherein

in the fourth battery cell, under a condition that a total mass of the first positive electrode active material and the second positive electrode active material is 100%, a mass of the first positive electrode active material accounts for 50% to 62.5%, and a mass of the second positive electrode active material accounts for 37.5% to 50%.

15. The battery pack according to claim 9 , wherein

under a condition that the first positive electrode active material is lithium nickel manganese cobalt oxide, and the second positive electrode active material is lithium iron phosphate, a mass ratio of the second positive electrode active material in the first battery cell to that in the second battery cell, that in the third battery cell, and that in the fourth battery cell is 1: (1-3):(3-5):(5-9);

under a condition that the first positive electrode active material is lithium nickel manganese cobalt oxide, and the second positive electrode active material is lithium titanate or lithium manganese oxide, a mass ratio of the second positive electrode active material in the first battery cell to that in the second battery cell, that in the third battery cell, and that in the fourth battery cell is 1:(1-2):(3-4):(5-7); and

under a condition that the first positive electrode active material is lithium iron phosphate, and the second positive electrode active material is lithium titanate or lithium manganese oxide, a mass ratio of the second positive electrode active material in the first battery cell to that in the second battery cell, that in the third battery cell, and that in the fourth battery cell is 1:(1-3):(3-5):(5-9).

16. The battery pack according to claim 1 , wherein

at a temperature below 0° C., a discharge cut-off voltage of the first battery cell is higher than a discharge cut-off voltage of the second battery cell by 0 V to 0.3 V, the discharge cut-off voltage of the second battery cell is higher than a discharge cut-off voltage of the third battery cell by 0 V to 0.3 V, the discharge cut-off voltage of the third battery cell is higher than a discharge cut-off voltage of the fourth battery cell by 0 V to 0.3 V, and the discharge cut-off voltage of the fourth battery cell is 1.6 V or more.

17. The battery pack according to claim 1 , wherein a plurality of first battery cells comprising the first battery cell is provided in the first area, a plurality of second battery cells comprising the second battery cell is provided in the second area, a plurality of third battery cells comprising the third battery cell is provided in the third area, and a plurality of fourth battery cells comprising the fourth battery cell is provided in the fourth area, and a ratio of a number of the first battery cells to that of the second battery cells, that of the third battery cells, and that of the fourth battery cells is (3-8):(8-13):(9-14): 1.

18. The battery pack according to claim 1 , wherein

capacitors are provided in gaps between different battery cells.

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

20. The power consuming device of claim 19 , wherein the power consuming device includes a mobile device, an electric vehicle, an electric train, a ship, a satellite, or an energy storage system.