Nonaqueous lithium storage element

Patent metadata

Field	Value
Publication number	US-9748045-B2
Application number	US-201314649809-A
Country	US
Kind code	B2
Filing date	Dec 5, 2013
Priority date	Dec 6, 2012
Publication date	Aug 29, 2017
Grant date	Aug 29, 2017

Abstract

Provided is a nonaqueous lithium storage element which is obtained by housing an electrode body and a nonaqueous electrolyte solution containing a lithium salt in an outer case, said electrode body being composed of a negative electrode that is composed of a negative electrode collector and a negative electrode active material layer laminated on one or both surfaces of the negative electrode collector, a positive electrode that is composed of a positive electrode collector and a positive electrode active material layer laminated on one or both surfaces of the positive electrode collector, and a separator.

First claim

The invention claimed is:

1. A nonaqueous lithium-type storage element comprising:
a casing;
an electrode body; and
a nonaqueous electrolytic solution comprising a lithium salt;
wherein the electrode body and nonaqueous electrolytic solution are stored within the casing, the electrode body comprises:
a negative electrode comprising a negative electrode collector, and a negative electrode active material layer laminated on one surface or both surfaces of the negative electrode collector;
a positive electrode comprising a positive electrode collector, and a positive electrode active material layer laminated on one surface or both surfaces of the positive electrode collector; and
a separator;

the negative electrode active material layer comprises a negative electrode active material,
the negative electrode active material comprises a composite porous material in which a pitch coal is deposited on a surface of an activated carbon,
the negative electrode active material satisfies following i) and ii):
i) a weight ratio of the pitch coal relative to the activated carbon is 10% to 55%, and a softening point of a pitch as a raw material of the pitch coal is 100° C. or lower; and
ii) the negative electrode active material has a BET specific surface area of 350 m 2 /g to 1500 m 2 /g, and is doped with lithium ions in an amount of 1100 mAh/g to 2000 mAh/g, and
initial-time lithium charge/discharge characteristics of the negative electrode active material satisfy following 1) and 2):
1) a charging amount is 1100 mAh/g to 2000 mAh/g; and
2) a discharging amount is 100 mAh/g or higher at a negative electrode potential of 0 to 0.5 V.

2. The nonaqueous lithium-type storage element according to claim 1 , wherein the negative electrode active material comprises the composite porous material in which the pitch coal is deposited on the surface of the activated carbon, and the composite porous material satisfies at least one of following I) to III):
I) 0.010≦Vm1≦0.300, and 0.010≦Vm2≦0.200;
II) 0.010≦Vm1≦0.200, and 0.200≦Vm2≦0.400; and
III) 0.010≦Vm1≦0.100, and 0.400≦Vm2≦0.650;

provided that Vm1 (cc/g) is a mesopore volume derived from a fine pore having a size of 20 Å to 500 Å, calculated by a BJH method, and Vm2 (cc/g) is a micropore volume derived from a fine pore having a size of smaller than 20 Å, calculated by a MP method.

3. The nonaqueous lithium-type storage element according to claim 1 , wherein the positive electrode active material layer comprises the positive electrode active material;
the positive electrode active material comprises an activated carbon having a BET specific surface area of 2600 m 2 /g to 4500 m 2 /g, a mesopore volume V1 (cc/g) of 0.8<V1≦2.5, derived from a fine pore having a size of 20 Å to 500 Å, calculated by the BJH method, a micropore volume V2 (cc/g) of 0.92<V2≦3.0, derived from a fine pore having a size of smaller than 20 Å, calculated by the MP method, and an average particle size of 1 μm to 30 μm; and
the positive electrode active material layer has a volume density of 0.40 g/cm 3 to 0.70 g/cm 3 .

4. The nonaqueous lithium-type storage element according to claim 3 , wherein, when the separator is maintained at 100° C. for 1 hour in a non-restrained state, the separator has a thermal shrinkage of 3% to 10% in a first direction, and a thermal shrinkage of 2% to 10% in a second direction which is orthogonal to the first direction,
a larger electrode area which is any one of an area of the positive electrode active material layer of the positive electrode and a negative electrode area of the negative electrode active material layer of the negative electrode, and an area of the separator have a following relationship:
(separator area)>(electrode area); and
X 1 and X 2 are both 0.5 to 8.0,
wherein X 1 is calculated by formula (1):
X 1 ={L 1 or L 1 ′/( A/ 2)}×100

wherein, in an arbitrary straight line which is parallel to the first direction of the separator and makes any one of L 1 and L 1 ′ the shortest, in a top view, A is a length of a portion where the electrode area in the arbitrary straight line and the separator overlap, and L 1 and L 1 ′ are lengths of portions where the electrode area and the separator do not overlap; and

wherein X 2 is calculated by formula (2):
X 2 ={L 2 or L 2 ′/( B/ 2)}×100

wherein, in an arbitrary straight line which is parallel to the second direction of the separator and makes any one of L 2 and L 2 ′ the shortest, in a top view, B is a length of a portion where the electrode area in the arbitrary straight line and the separator overlap, and L 2 and L 2 ′ are lengths of portions where the electrode area and the separator do not overlap.

5. The nonaqueous lithium-type storage element according to claim 1 , wherein the weight ratio of the pitch coal relative to the activated carbon is 10% to 50%.

Assignees

• Asahi Chemical Ind

Inventors

• Okada Nobuhiro
• Kamijo Takeshi
• Mori Shiro
• Yamasaki Takashi
• Kaneko Akiko

Classifications

• H01M4/587

  for inserting or intercalating light metals · CPC title

• H01G11/52

  Separators · CPC title

• H01M4/02

  Electrodes composed of, or comprising, active material · 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

• H01G11/38

  Carbon pastes or blends; Binders or additives therein · CPC title