Nonaqueous lithium power storage element

Patent metadata

Field	Value
Publication number	US-10468199-B2
Application number	US-201716070422-A
Country	US
Kind code	B2
Filing date	Jan 20, 2017
Priority date	Jan 22, 2016
Publication date	Nov 5, 2019
Grant date	Nov 5, 2019

Abstract

This nonaqueous lithium power storage element contains a positive electrode, a negative electrode, a separator, and a nonaqueous electrolyte that contains lithium ions. The positive electrode has a positive electrode current collector and a positive electrode active material layer disposed on one surface or both surfaces of the positive electrode current collector, and the positive electrode active material layer contains a positive electrode active material that contains a carbon material. When the pore distribution of the positive electrode active material layer is measured by mercury intrusion, the pore distribution curve for the relationship between the pore diameter and log differential pore volume has at least one peak having a peak value of 1.0-5.0 mL/g for the log differential pore volume in the pore diameter range of 0.1-50 μm, and the total cumulative pore volume Vp in the pore diameter range of 0.1-50 μm is 0.7-3.0 mL/g.

First claim

The invention claimed is:

1. A nonaqueous lithium power storage element containing a positive electrode, a negative electrode, a separator and a nonaqueous electrolytic solution containing lithium ion, wherein
the positive electrode has a positive electrode power collector and a positive electrode active material layer disposed on one or both sides of the positive electrode power collector, the positive electrode active material layer comprising a positive electrode active material containing a carbon material,
the negative electrode has a negative electrode power collector and a negative electrode active material layer disposed on one or both sides of the negative electrode power collector, the negative electrode active material layer comprising a negative electrode active material that can intercalate and release lithium ions, and
in a pore distribution of the positive electrode active material layer measured by a mercury intrusion method, a pore distribution curve for a relationship between a pore diameter of the positive electrode active material layer and a log differential pore volume of the positive electrode active material layer has at least one peak with a peak value of 1.0 mL/g to 5.0 mL/g for the log differential pore volume in the pore diameter range of 0.1 μm to 50 μm, and a total cumulative pore volume Vp of the positive electrode active material layer in the pore diameter range of 0.1 μm to 50 μm is 0.7 mL/g to 3.0 mL/g.

2. The nonaqueous lithium power storage element according to claim 1 , wherein the pore distribution curve for the positive electrode active material layer has at least two peaks with a peak value of 0.5 mL/g to 5.0 mL/g for the log differential pore volume in the pore diameter range of 0.1 μm to 50 μm.

3. The nonaqueous lithium power storage element according to claim 2 , wherein the pore distribution curve for the positive electrode active material layer has at least two peaks in the pore diameter range of 0.3 μm to 20 μm.

4. The nonaqueous lithium power storage element according to claim 1 , wherein the positive electrode contains a lithium compound other than the positive electrode active material.

5. The nonaqueous lithium power storage element according to claim 4 , wherein the lithium compound is one or more types selected from the group consisting of lithium carbonate, lithium oxide and lithium hydroxide.

6. The nonaqueous lithium power storage element according to claim 4 , wherein the lithium compound in the positive electrode is lithium carbonate.

7. The nonaqueous lithium power storage element according to claim 4 , wherein the amount of lithium compound in the positive electrode is 1 weight % to 50 weight %, based on the weight of the positive electrode active material layer.

8. The nonaqueous lithium power storage element according to claim 4 , wherein 0.1 μm≤Y 1 ≤10 μm, where Y 1 is the mean particle diameter of the lithium compound, 2 μm≤Z 1 ≤20 μm, where Z 1 is the mean particle diameter of the positive electrode active material, and Y 1 <Z 1 .

9. The nonaqueous lithium power storage element according to claim 4 , wherein the proportion A 1 of voids with an area of 0.2 μm 2 to 250 μm 2 in a cross-sectional SEM image of the positive electrode active material layer is 10% to 60% per unit area of the positive electrode active material layer.

10. The nonaqueous lithium power storage element according to claim 9 , wherein 1.0≤B 1 /4C 1 ≤3.5 is satisfied, where B 1 is the total circumferential length of voids with an area of 0.2 μm 2 to 250 μm 2 in a cross-sectional SEM image of the positive electrode active material layer, and C 1 is the total of the square roots of the areas of voids with an area of 0.2 μm 2 to 250 μm 2 .

11. The nonaqueous lithium power storage element according to claim 9 , wherein in a cross-sectional SEM image of the positive electrode active material layer, voids are present surrounding the lithium compound in the positive electrode active material layer, and X 1 >Y 1 is satisfied, where X 1 is the mean size of the voids.

12. The nonaqueous lithium power storage element according to claim 4 , wherein 0.3≤A≤5.0, 0.5≤B≤10, 0.05≤C≤3.0 and 0.4≤A/B≤1.5 are satisfied, where A (μL/cm 2 ) is the mesopore volume per unit area due to pores with diameters of 20 Å to 500 Å, as calculated by the BJH method in nitrogen gas adsorption measurement for each side of the positive electrode, B (μL/cm 2 ) is the micropore volume per unit area due to pores with diameters of smaller than 20 Å, as calculated by the MP method in the nitrogen gas adsorption measurement, and C (μL/cm 2 ) is the ultramicropore volume per unit area due to pores with diameters of smaller than 7 Å, as calculated by the DFT method in carbon dioxide gas adsorption measurement for each side of the positive electrode.

13. The nonaqueous lithium power storage element according to claim 12 , wherein 1≤D≤20 is satisfied, where D (m 2 /cm 2 ) is the specific surface area per unit area as calculated by the BET method in nitrogen gas adsorption measurement, for each side of the positive electrode.

14. The nonaqueous lithium power storage element according to claim 1 , wherein the area overlap ratio A 2 of fluorine mapping with respect to oxygen mapping, binarized based on the mean value of brightness, is 40% to 99%, in element mapping of the positive electrode surface by SEM-EDX.

15. The nonaqueous lithium power storage element according to claim 1 , wherein the area overlap ratio A 3 of fluorine mapping with respect to oxygen mapping, binarized based on the mean value of brightness, is 10% to 60%, in element mapping of a broad ion beam (BIB) processed cross-section of the positive electrode by SEM-EDX.

16. The nonaqueous lithium power storage element according to claim 1 , wherein the volume of pores of 20 Å to 350 Å as calculated by QSDFT (Quenching Solid Density Functional Theory) in the negative electrode active material layer is 50% to 100% of the volume of pores of 0 Å to 350 Å as calculated by QSDFT.

17. The nonaqueous lithium power storage element according to claim 16 , wherein the volume of pores of 20 Å to 250 Å as calculated by QSDFT in the negative electrode active material layer is 40% to 90% of the volume of pores of 0 Å to 350 Å as calculated by QSDFT.

18. The nonaqueous lithium power storage element according to claim 16 , wherein the specific surface area of 20 Å to 350 Å as calculated by QSDFT in the negative electrode active material layer is 20% to 100% of the specific surface area of 0 Å to 350 Å as calculated by QSDFT.

19. The nonaqueous lithium power storage element according to claim 16 , wherein the mean pore size of the negative electrode active material layer is 2 nm to 20 nm.

20. The nonaqueous lithium power storage element according to claim 1 , wherein the positive electrode active material comprises activated carbon as the carbon material.

21. The nonaqueous lithium power storage element according to claim 20 , wherein the activated carbon satisfies 0.3<V 1 ≤0.8 and 0.5≤V 2 ≤1.0, where V 1 (cc/g) is the mesopore volume due to pores with diameters of 20 Å to 500 Å as calculated by the BJH method, and V 2 (cc/g) is the micropore volume due to pores with diameters of smaller than 20 Å as calculated by the MP method, and has a specific surface area of 1,500 m 2 /g to 3,000 m 2 /g, as measured by the BET method.

22. The nonaqueous lithium power storage element according to claim 20 , wherein the activated carbon satisfies 0.8<V 1 ≤2.5, where V

Assignees

• Asahi Chemical Ind

Inventors

• Kusuzaka Keita
• Umetsu Kazuteru
• Okada Nobuhiro
• Kamijo Tekeshi
• Hosokibara Atsushi
• Matsushita Tadashi

Classifications

• H01G11/34

  characterised by carbonisation or activation of carbon · CPC title

• H01G11/24

  characterised by structural features of the materials making up or comprised in the electrodes, e.g. form, surface area or porosity; characterised by the structural features of powders or particles used therefor · CPC title

• H01M10/0585

  of accumulators having only flat construction elements, i.e. flat positive electrodes, flat negative electrodes and flat separators · CPC title

• H01M10/0567

  characterised by the additives · CPC title

• H01M10/052

  Li-accumulators · CPC title