NEGATIVE ELECTRODE FOR NONAQUEOUS ELECTROLYTE SECONDARY BATTERY, ITS MANUFACTURING METHOD, AND NONAQUEOUS ELECTROLYTE SECONDARY BATTERY USING THE SAME
A negative electrode for nonaqueous electrolyte secondary battery comprising a current collector with a concave and a convex formed at least on one surface thereof, and a column member having n (n≧2) stages of laminated columnar portions obliquely formed on the convex of the current collector, wherein a layer being less in expansion and contraction due to insertion and extraction of lithium ion is disposed in the column member.
1 . A negative electrode for nonaqueous electrolyte secondary battery inserting and extracting lithium ion in a reversible fashion, comprising:
a current collector with at least a concave and a convex formed on one surface thereof, and
a column member having n (n≧2) stages of laminated columnar portions obliquely formed on the convex of the current collector,
wherein a layer being less in expansion and contraction due to insertion and extraction of the lithium ion is disposed in the column member.
2 . The negative electrode for nonaqueous electrolyte secondary battery of claim 1 ,
wherein a layer being less in expansion and contraction is disposed near both ends of the columnar portion in the direction of height.
3 . The negative electrode for nonaqueous electrolyte secondary battery of claim 1 ,
wherein a layer being less in expansion and contraction is disposed near the middle of the columnar portion in the direction of height.
4 . The negative electrode for nonaqueous electrolyte secondary battery of claim 1 ,
wherein a layer being less in expansion and contraction is disposed on an outer periphery surface of the columnar portion or a part of outer periphery surfaces of the columnar portions laminated in two or more stages.
5 . The negative electrode for nonaqueous electrolyte secondary battery of claim 1 ,
wherein the layer being less in expansion and contraction which is disposed on the column member is formed by sequentially changing a ratio of contained elements of the column member.
6 . The negative electrode for nonaqueous electrolyte secondary battery of claim 1 ,
wherein a changing direction of the ratio of contained elements in a longitudinal direction of the current collector is different between an even-numbered stage and an odd-numbered stage of the columnar portions of the column member.
7 . The negative electrode for nonaqueous electrolyte secondary battery of claim 1 ,
wherein at least in a state of discharging, n stages of the columnar portions of the column member are obliquely formed on the convex of the current collector, and its odd-numbered stages and even-numbered stages are laminated in a zigzag fashion.
8 . The negative electrode for nonaqueous electrolyte secondary battery of claim 1 ,
wherein at least in a state of charging, an acute angle formed by a center line in oblique direction of the columnar portion and a center line in thickness direction of the current collector is larger than the angle in a state of discharging.
9 . The negative electrode for nonaqueous electrolyte secondary battery of claim 1 ,
wherein a negative electrode active material whose theoretical capacity density for inserting and extracting lithium ion in a reversible fashion at least exceeds 833 mAh/cm 3 is used as the column member and the columnar portion.
10 . The negative electrode for nonaqueous electrolyte secondary battery of claim 9 ,
wherein a material represented by SiOx including silicon at least is used as the negative electrode active material.
11 . The negative electrode for nonaqueous electrolyte secondary battery of claim 10 ,
wherein the value of x of the material represented by SiOx including silicon is continuously increased from an acute angle forming side toward an obtuse angle forming side with respect to a crossing angle between a center line in oblique direction of the columnar portion and a center line in thickness direction of the current collector.
12 . The negative electrode for nonaqueous electrolyte secondary battery of claim 2 ,
wherein a layer being less in expansion and contraction is disposed with value x of the material represented by SiOx including silicon increased in the vicinity of both ends or middle in height direction of the columnar portion.
13 . The negative electrode for nonaqueous electrolyte secondary battery of claim 4 ,
wherein a layer being less in expansion and contraction is disposed with value x of the material represented by SiOx including silicon increased at an outer periphery surface of the columnar portion.
14 . A method of manufacturing a negative electrode for nonaqueous electrolyte secondary battery inserting and extracting lithium ion in a reversible fashion, comprising:
a first step of forming at least a concave and a convex on one surface of a current collector;
a second step of obliquely forming a first stage columnar portion on the convex while moving the current collector in a direction of increasing an angle formed by an evaporation source and the normal line of the current collector; and
a third step of forming a second stage columnar portion obliquely rising in a direction different from the oblique direction of the first stage columnar portion while moving the current collector in a direction of decreasing the angle,
wherein the second step and the third step are repeated twice at least to form a column member formed of n (n≧2) stages which are different in oblique direction of the columnar portion between an odd-numbered stage and an even-numbered stage, and
at least any one of the steps for forming the columnar portions includes a step of forming a layer being less in expansion and contraction due to insertion and extraction of lithium ion.
15 . The method of manufacturing a negative electrode for nonaqueous electrolyte secondary battery of claim 14 ,
wherein the layer being less in expansion and contraction is formed near both ends in height direction of the columnar portion.
16 . The method of manufacturing a negative electrode for nonaqueous electrolyte secondary battery of claim 14 ,
wherein the layer being less in expansion and contraction is formed near a middle portion in height direction of the columnar portion.
17 . The method of manufacturing a negative electrode for nonaqueous electrolyte secondary battery of claim 14 ,
wherein the layer being less in expansion and contraction is formed on an outer periphery surface of the column member or a part of outer periphery surfaces of the columnar portions laminated in two or more stages.
18 . The method of manufacturing a negative electrode for nonaqueous electrolyte secondary battery of claim 14 ,
wherein the angle changing direction of the current collector against the evaporation source is different between the odd-numbered stage and the even-numbered stage.
19 . A nonaqueous electrolyte secondary battery, comprising:
the negative electrode for nonaqueous electrolyte secondary battery of claim 1 ,
a positive electrode for inserting and extracting lithium ion in a reversible fashion, and
nonaqueous electrolyte.
20 . The negative electrode for nonaqueous electrolyte secondary battery of claim 6 ,
wherein at least in a state of discharging, n stages of the columnar portions of the column member are obliquely formed on the convex of the current collector, and its odd-numbered stages and even-numbered stages are laminated in a zigzag fashion.
21 . The negative electrode for nonaqueous electrolyte secondary battery of claim 6 ,
wherein at least in a state of charging, an acute angle formed by a center line in oblique direction of the columnar portion and a center line in thickness direction of the current collector is larger than the angle in a state of discharging.
22 . The negative electrode for nonaqueous electrolyte secondary battery of claim 3 ,
wherein a layer being less in expansion and contraction is disposed with value x of the material represented by SiOx including silicon increased in the vicinity of both ends or middle in height direction of the columnar portion.