Nonaqueous lithium power storage element

Patent metadata

Field	Value
Publication number	US-10886533-B2
Application number	US-201716070425-A
Country	US
Kind code	B2
Filing date	Jan 20, 2017
Priority date	Jan 22, 2016
Publication date	Jan 5, 2021
Grant date	Jan 5, 2021

Abstract

Provided is a nonaqueous lithium power storage element that can suppress excessive decomposition of a lithium compound remaining in a positive electrode, can suppress gas generation at high voltages, and can suppress capacity declines during high-load charge/discharge cycling. The nonaqueous lithium power storage element according to the present embodiment has a positive electrode that contains a lithium compound other than an active material, a negative electrode, a separator, and a lithium ion-containing nonaqueous electrolyte, wherein in the elemental map provided by SEM-EDX of the surface of the positive electrode, the area overlap ratio U 1 of the fluorine map relative to the oxygen map, as provided by binarization based on the average value of the brightness values, is 40% to 99%.

First claim

The invention claimed is:

1. A nonaqueous lithium power storage element having at least one positive electrode, at least one negative electrode, at least one separator, and a lithium ion-containing nonaqueous electrolytic solution,
wherein the positive electrode has a positive electrode power collector and a positive electrode active material layer on one or both sides of the positive electrode power collector, and the positive electrode active material layer contains a positive electrode active material and a lithium compound other than the positive electrode active material,
wherein an amount of the lithium compound is 1 weight % to 50 weight % based on the total weight of the positive electrode active material layer,
wherein the positive electrode active material contains 50 wt % or more of an activated carbon based on the total weight of the positive electrode active material,
wherein in elemental mapping obtained by SEM-EDX of the positive electrode surface, an area overlapping ratio U 1 of fluorine mapping relative to oxygen mapping, as binarized based on the average value of brightness, is 40% to 99%,
wherein the area overlapping ratio U 1 =100×(the area of overlapping between oxygen mapping and fluorine mapping)/(the area of oxygen mapping), in a binarized SEM-EDX elemental mapping image of the positive electrode surface,
wherein the lithium compound is at least one selected from among lithium carbonate, lithium hydroxide and lithium oxide,
wherein a coating film formed from a fluorine containing compound is formed on the surface of the lithium compound, and
wherein 0.1 μm≤G 1 ≤10 μm, where G 1 is the mean particle diameter of the lithium compound, and 2 μm≤H 1 ≤20 μm and G 1 <H 1 , where H 1 is the mean particle diameter of the positive electrode active material.

2. The nonaqueous lithium power storage element according to claim 1 , wherein an area overlapping ratio U 2 of fluorine mapping relative to oxygen mapping, as binarized based on the average value of brightness, is 10% to 60%, in element mapping of a Broad Ion Beam (BIB)-processed positive electrode cross-section by SEM-EDX, wherein the area overlapping ratio U 2 is calculated based on the following formula: U 2 =100×(the area of overlapping between oxygen mapping and fluorine mapping)/(the area of oxygen mapping), in a binarized SEM-EDX elemental mapping image of the BIB-processed positive electrode cross-section.

3. The nonaqueous lithium power storage element according to claim 1 , wherein power collectors of the positive electrode and the negative electrode are metal foils without through-holes.

4. The nonaqueous lithium power storage element according to claim 1 , wherein, in an image obtained by microscopic Raman spectroscopy of a cross-section of the positive electrode, an area ratio S of carbonate ion mapping of the cross section of the positive electrode is 1% to 50%, wherein the area ratio S is calculated based on the following formula: S=100×(mapping frequency for CO 3 2− ion)/2700, in a histogram for peak areas of CO 3 2− in the area of from 1071 cm −1 to 1104 cm −1 in the Raman spectra measured at 2700 points of the image obtained by microscopic Raman spectroscopy.

5. The nonaqueous lithium power storage element according to claim 1 , wherein the lithium compound is lithium carbonate.

6. The nonaqueous lithium power storage element according to claim 5 , which is a nonaqueous lithium power storage element comprising:
an electrode laminated body or wound electrode comprising at least two positive electrodes that contain a positive electrode active material and lithium carbonate, at least one negative electrode and at least two separators, and having the positive electrode and the negative electrode laminated or wound across the separator; and
the lithium ion-containing nonaqueous electrolytic solution;
wherein
at least one of the positive electrodes contains a nonporous positive electrode power collector and has the positive electrode active material coated on both sides of the nonporous positive electrode power collector,
at least one of the negative electrodes contains a nonporous negative electrode power collector and has a negative electrode active material capable of intercalating and releasing lithium ions coated on both sides of the nonporous negative electrode power collector,
in the electrode laminated body or wound electrode, at least one of the negative electrodes faces at least two of the positive electrodes across the separator,
the electrode laminated body or wound electrode contains the positive electrode as at least one outermost layer, the positive electrode of the outermost layer having a positive electrode active material layer C x side that does not face a negative electrode,
C x1 is 5.0 to 25.0, where C x1 (g/m 2 ) is the amount of lithium carbonate per area contained on the C x side, and
C y1 is 0.1 to 15.0 and C x1 >C y1 , where the C y side is the positive electrode active material layer on the back side of the C x side and C y1 (g/m 2 ) is the amount of lithium carbonate per area contained on the C y side.

7. The nonaqueous lithium power storage element according to claim 6 , wherein C x2 /C y2 is 0.86 to 1.14, where C x2 (g/m 2 ) is the amount of active material per area contained on the C x side, and C y2 (g/m 2 ) is the amount of active material per area contained on the C side.

8. The nonaqueous lithium power storage element according to claim 6 , wherein in an image obtained by microscopic Raman spectroscopy of the C x side, S x is 10% to 50%, where S x is the area ratio of carbonate ion mapping, wherein the area ratio S x is calculated based on the following formula: S x =100×(mapping frequency for CO 3 2− ion)/2700, in a histogram for peak areas of CO 3 2− in the area of from 1071 cm −1 to 1104 cm −1 in the Raman spectra measured at 2700 points of the image obtained by microscopic Raman spectroscopy.

9. The nonaqueous lithium power storage element according to claim 8 , wherein in an image obtained by microscopic Raman spectroscopy of the C y side, S y is 1% to 40% and S y <S x , where S y is the area ratio of carbonate ion mapping, wherein the area ratio S y is calculated based on the following formula: S x =100×(mapping frequency for CO 3 2− ion)/2700, in a histogram for peak areas of CO 3 2− in the area of from 1071 cm −1 to 1104 cm −1 in the Raman spectra measured at 2700 points of the image obtained by microscopic Raman spectroscopy.

10. The nonaqueous lithium power storage element according to claim 6 , wherein
the C y side contains one or more compounds represented by the following formulas (1) to (3):
LiX 1 —OR 1 O—X 2 Li  formula (1)

where R 1 is an alkylene group of 1 to 4 carbon atoms or a halogenated alkylene group of 1 to 4 carbon atoms, and X 1 and X 2 respectively and independently represent —(COO) n (where n is 0 or 1),
LiX 1 —OR 1 O—X 2 R 2   formula (2)

where R 1 is an alkylene group of 1 to 4 carbon atoms or a halogenated alkylene group of 1 to 4 carbon atoms, R 2 is hydrogen, an alkyl group of 1 to 10 carbon atoms, a mono- or polyhydroxyalkyl group of 1 to 10 carbon atoms, an alkenyl group of 2 to 10 carbon atoms, a mono- or polyhydroxyalkenyl group of 2 to 10 carbon atoms, a cycloalkyl group of 3 to 6 carbon atoms, or an aryl group, and X 1 and X 2 respectively and independently represent —(COO) n (where n is 0 or 1), and
R 2 X 1 —OR 1 O—X 2 R 3   formula (3)

where R 1 is an alkylene group of 1 to 4 carbon atoms or a halogenated alkylene group of 1 to 4 carbon atoms, R 2 and R 3 respectively and independently represent hydrogen, an alkyl group of 1 to 10 carbon atoms, a polyhy

Assignees

• Asahi Chemical Ind

Inventors

• Umetsu Kazuteru
• Okada Nobuhiro
• Hiraoka Koichi
• Hosokibara Atsushi
• Suetomi Taku

Classifications

• Y02P70/50

  Manufacturing or production processes characterised by the final manufactured product · CPC title

• H01M10/0525

  Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries · CPC title

• H01M4/1393

  of electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx · CPC title

• H01G11/58

  Liquid electrolytes · CPC title

• H01G11/06 Primary

  with one of the electrodes allowing ions to be reversibly doped thereinto, e.g. lithium ion capacitors [LIC] · CPC title