Porous electrode base material, method for manufacturing same, and precursor sheet
View Patent ↗The present invention relates to a method for manufacturing a porous electrode base material including the following steps [1] to [3]: [1] a step for dispersing short carbon fibers (A) to form a sheet-form product; [2] a step for adding, to the sheet-form product, at least one phenolic resin (c) selected from a group consisting of a water soluble phenolic resin and a water dispersible phenolic resin along with carbon powder (d) to form a precursor sheet; and [3] a step for carbonizing the precursor sheet at the temperature of 1000° C. or higher, after the step [2].
1. A method for manufacturing a porous electrode base material, the method comprising:
[1] dispersing short carbon fibers (A) to form a sheet-form product;
[2] adding, to the sheet-form product, at least one phenolic resin (c) comprising a water soluble phenolic resin and a water dispersible phenolic resin along with carbon powder (d) to form a precursor sheet;
[3] carbonizing the precursor sheet at a temperature of 1000° C. or higher, after said adding [2]; and
[4] after said dispersing [1] and before said adding [2], performing an entanglement treatment of the sheet-form product.
2. The manufacturing method according to claim 1 , further comprising:
[7] after said performing [4] and before said adding [2], performing a first drying treatment of the sheet-form product,
[5] after said adding [2] and before said carbonizing [3], heating and compressing the precursor sheet at a temperature of 100 to 250° C., and
[6] after said adding [2] and before said heating and compressing [5], performing a second drying treatment of the precursor sheet.
3. The manufacturing method according to claim 1 , wherein an average particle diameter of substantial particles or agglomerates of the carbon powder (d) in said adding [2] is 0.1 to 50 μm.
4. The manufacturing method according to claim 1 , further comprising:
[8] after said carbonizing [3], adding a fluorine-based resin dispersion with a solid content of 1 to 30% by mass to the porous electrode base material followed by further drying and performing a heat treatment at 300 to 390° C.
5. A porous electrode base material, comprising:
a sheet-form structure having short carbon fibers (A) bound by a resin carbide (C) derived from a water soluble phenolic resin and a water dispersible phenolic resin,
wherein carbon powder (d) is localized in the vicinity of a surface layer of a single side or both sides of the sheet-form structure.
6. The porous electrode base material of claim 5 ,
wherein a region having the short carbon fibers (A) and carbon powder (d) bound by the resin carbide (C) is localized in the vicinity of a surface layer of a single side or both sides of the sheet-form structure.
7. The porous electrode base material of claim 5 ,
wherein a region having the short carbon fibers (A) and carbon powder (d) bound by the resin carbide (C) is included in the vicinity of a surface layer of a single side or both sides of the sheet-form structure,
a pore occupancy in a region X from a surface of a plane having the aforementioned region to a depth of 20 μm is less than 30%, and
a pore occupancy in a region Y from center of the sheet-form structure to a depth of 40 μm in a thickness direction is 50 to 90%.
8. A porous electrode base material, comprising:
a sheet-form structure having short carbon fibers (A) bound by carbon fibers (B) with a fiber diameter of 0.1 to 5 μm and a resin carbide (C) derived from a water soluble phenolic resin and a water dispersible phenolic resin,
wherein the short carbon fibers (A) form a three-dimensional entanglement structure in the sheet-form structure, and
carbon powder (d) is localized in the vicinity of a surface layer of a single side or both sides of the sheet-form structure.
9. The porous electrode base material of claim 8 ,
wherein
a region having the short carbon fibers (A) and carbon powder (d) bound by the resin carbide (C) is localized in the vicinity of a surface layer of a single side or both sides of the sheet-form structure.
10. The porous electrode base material of claim 8 ,
wherein
a region having the short carbon fibers (A) and carbon powder (d) bound by the resin carbide (C) is included in the vicinity of a surface layer of a single side or both sides of the sheet-form structure,
a pore occupancy in a region X from a surface of a plane having the aforementioned region to a depth of 20μm is less than 30%, and
a pore occupancy in a region Y from center of the sheet-form structure to a depth of 40 μm in a thickness direction is 50 to 90%.
11. A precursor sheet, comprising:
a sheet-form structure having short carbon fibers (A) bound by at least one phenolic resin (c) comprising a water soluble phenolic resin and a water dispersible phenolic resin,
wherein carbon powder (d) is localized in the vicinity of a surface layer of a single side or both sides of the sheet-form structure.
12. A precursor sheet, comprising:
a sheet-form structure having short carbon fibers (A) bound by at least one phenolic resin (c) comprising a water soluble phenolic resin and a water dispersible phenolic resin,
wherein a region having the short carbon fibers (A) and carbon powder (d) bound by the phenolic resin (c) is localized in the vicinity of a surface layer of a single side or both sides of the sheet-form structure.
13. A precursor sheet, comprising:
a sheet-form structure having short carbon fibers (A) bound by at least one phenolic resin (c) comprising a water soluble phenolic resin and a water dispersible phenolic resin,
wherein a region having the short carbon fibers (A) and carbon powder (d) bound by the phenolic resin (c) is included in the vicinity of a surface layer of a single side or both sides of the sheet-form structure,
a pore occupancy in a region X from a surface of a plane having the aforementioned region to a depth of 20 μm is less than 25%, and
a pore occupancy in a region Y from center of the sheet-form structure to a depth of 40 μm in a thickness direction is 35 to 70%.
14. A precursor sheet, comprising:
a sheet-form structure having short carbon fibers (A) and carbon fiber precursor short fibers (b) bound by at least one phenolic resin (c) comprising a water soluble phenolic resin and a water dispersible phenolic resin,
wherein the short carbon fibers (A) form a three-dimensional entanglement structure in the sheet-form structure, and
a region having the short carbon fibers (A) and carbon powder (d) bound by the phenolic resin (c) is localized in the vicinity of a surface layer of a single side or both sides of the sheet-form structure.
15. The method of claim 1 , wherein the sheet-form product, prior to [2] adding the phenolic resin (c), does not comprise a binder.
16. The method of claim 1 , wherein the process does not comprise organic solvent removal from the sheet-form product, prior to [2] adding the phenolic resin (c).