Lithium secondary battery pack, as well as electronic device, charging system, and charging method using said pack
A lithium secondary battery pack of the present invention includes: a lithium secondary battery including an electrode body formed of a positive electrode and a negative electrode facing each other and a separator interposed therebetween, and a non-aqueous electrolyte; a PTC element; and a protection circuit including a field effect transistor. The lithium secondary battery has an energy density per volume of 450 Wh/L or more, the lithium secondary battery has a current density of 3.0 mA/cm 2 or less, and a relational expression (1) and a relational expression (2) below are established where A (mΩ) is an impedance of the lithium secondary battery and B (mΩ) is an impedance of the entire circuit unit of the lithium secondary battery pack excepting the impedance A (mΩ) of the lithium secondary battery: A≤50 mΩ (1) B/A≤1 (2).
1. A lithium secondary battery pack comprising:
a lithium secondary battery comprising an electrode body formed of a positive electrode and a negative electrode facing each other and a separator interposed therebetween, and a non-aqueous electrolyte; a PTC element; and a protection circuit comprising a field effect transistor,
wherein the negative electrode comprises a negative electrode material mixture layer that contains an Si-containing material as a negative electrode active material,
the lithium secondary battery has an energy density per volume of 450 Wh/L or more,
the lithium secondary battery has a current density of 3.0 mA/cm 2 or less, and
a relational expression (1) and a relational expression (2) below are established where A (mΩ) is an impedance of the lithium secondary battery, B (mΩ) is an impedance of an entire circuit unit of the lithium secondary battery pack excepting the impedance A (mΩ) of the lithium secondary battery, and the impedance B (mΩ) is determined by subtracting the impedance A (mΩ) from the impedance of the entire circuit unit of the lithium secondary battery pack:
A≤50 mΩ (1)
B/A≤1 (2).
2. The lithium secondary battery pack according to claim 1 , wherein the Si-containing material is a material containing Si and O as constituent elements.
3. The lithium secondary battery pack according to claim 1 , wherein the Si-containing material is a composite comprising a material containing Si and O as constituent elements serving as a core material and a carbon coating layer formed on a surface of the core material.
4. The lithium secondary battery pack according to claim 3 , wherein the material containing Si and O as constituent elements is a material represented by a general compositional formula SiO x , where x is 0.5≤x≤1.5.
5. The lithium secondary battery pack according to claim 2 , wherein the material containing Si and O as constituent elements is a material represented by a general compositional formula SiO x , where x is 0.5≤x≤1.5.
6. The lithium secondary battery pack according to claim 1 , wherein the positive electrode comprises a positive electrode material mixture layer containing a Ni-containing material as a positive electrode active material.
7. An electronic device comprising the lithium secondary battery pack according to claim 6 .
8. A charging system comprising the lithium secondary battery pack according to claim 5 .
9. A charging method comprising the lithium secondary battery pack according to claim 6 .
10. An electronic device comprising the lithium secondary battery pack according to claim 1 .
11. A charging system comprising the lithium secondary battery pack according to claim 1 .
12. A charging method comprising the lithium secondary battery pack according to claim 1 .
13. A lithium secondary battery pack comprising:
a lithium secondary battery comprising an electrode body formed of a positive electrode and a negative electrode facing each other and a separator interposed therebetween, and a non-aqueous electrolyte; a PTC element; and a protection circuit comprising a field effect transistor,
wherein the positive electrode comprises a positive electrode material mixture layer that contains a Ni-containing material as a positive electrode active material,
the lithium secondary battery has an energy density per volume of 450 Wh/L or more,
the lithium secondary battery has a current density of 3.0 mA/cm 2 or less, and
a relational expression (1) and a relational expression (2) below are established where A (mΩ) is an impedance of the lithium secondary battery, B (mΩ) is an impedance of an entire circuit unit of the lithium secondary battery pack excepting the impedance A (mΩ) of the lithium secondary battery, and the impedance B (mΩ) is determined by subtracting the impedance A (mΩ) from the impedance of the entire circuit unit of the lithium secondary battery pack:
A≤50 mΩ (1)
B/A≤1 (2).
14. An electronic device comprising the lithium secondary battery pack according to claim 13 .
15. A charging system comprising the lithium secondary battery pack according to claim 13 .
16. A charging method comprising the lithium secondary battery pack according to claim 13 .
17. The lithium secondary battery pack of claim 1, wherein the impedance index B/A of relational expression (2) is established as:
B/A≤0.8 (2).
18. The lithium secondary battery pack of claim 1, wherein the impedance index B/A of relational expression (2) is established as:
B/A≤0.4 (2).
19. The lithium secondary battery pack of claim 1, wherein the impedance index B/A of relational expression (2) is established as:
0.71≤B/A≤0.86 (2).
20. The lithium secondary battery pack of claim 1, wherein the lithium secondary battery pack further comprises a PTC element.
21. The lithium secondary battery pack of claim 13, wherein the impedance index B/A of relational expression (2) is established as:
B/A≤0.8 (2).
22. The lithium secondary battery pack of claim 13, wherein the impedance index B/A of relational expression (2) is established as:
B/A≤0.4 (2).
23. The lithium secondary battery pack of claim 13, wherein the impedance index B/A of relational expression (2) is established as:
0.71≤B/A≤0.86 (2).
24. The lithium secondary battery pack of claim 13, wherein the lithium secondary battery pack further comprises a PTC element.