Diaphragm paper, and preparation method and application thereof

Abstract

Diaphragm paper, and a preparation method and an application thereof. The diaphragm paper comprises a first layer, a second layer, and a third layer, wherein the second layer is located between the first layer and the third layer; the first layer and the third layer are loose layers, of which the average aperture is larger than 10 m and the basis weight is 5 to 30 g/m.sup.2; and the second layer is a compact layer, of which the average aperture is smaller than 5 m and the basis weight is 2 to 15 g/m.sup.2. The compact layer has small aperture and good insulating performance, and is capable of effectively insulating a positive electrode and a negative electrode. The loose layers have good liquid permeability and electrolyte absorptivity, and can guarantee the discharge performance of a battery. The material is further advantageous in having good dimensional stability and being thin, so that a battery can achieve high capacity.

Claims

1. A diaphragm paper, comprising a first layer, a second layer and a third layer, the second layer is located between the first layer and the third layer; wherein, the first layer and the third layer are loose layers, with an average pore size greater than 10 m and a basis weight of 5 to 30 g/m.sup.2, the first layer contains hardwood pulp with a beating degree of 11-30 SR and a fiber length of 0.6-2 mm, viscose fiber with a fineness of 0.9 dtex and a fiber length of 3 mm, formalized polyvinyl alcohol fiber with a fineness of 1.0 dtex and a fiber length of 3 mm, and water-soluble polyvinyl alcohol fiber with a fineness of 1.11 dtex, a fiber length of 3 mm and a water soluble temperature of 70 C., the third layer contains hardwood pulp with a beating degree of 11-30 SR and a fiber length of 0.6-2 mm, viscose fiber with a fineness of 0.5 dtex and a fiber length of 3 mm, polyvinyl alcohol fiber with a fineness of 1.11 dtex and a fiber length of 3 mm, and water-soluble polyvinyl alcohol fiber with a fineness of 1.1 dtex, a fiber length of 3 mm, and a water soluble temperature of 70 C.; the second layer is a compact layer, with an average pore size lesser than 5 m and a basis weight of 2 to 15 g/m.sup.2, contains tencel fibrillated fiber with a beating degree of 60-80 SR, superfine polyvinyl alcohol fiber with a fineness of 0.5 dtex and a fiber length of 2 mm, and water-soluble polyvinyl alcohol fiber with a fineness of 1.1 dtex, a fiber length of 3 mm and a water soluble temperature of 70 C.

2. The diaphragm paper according to claim 1, wherein, the first layer and the third layer each independently accounts for 20 wt % to 40 wt % of the total mass of the diaphragm paper, the second layer accounts for 20 wt % to 60 wt % of the total mass of the diaphragm paper.

3. The diaphragm paper according to claim 1, wherein, further comprising 0.1% to 1% of a sizing layer based on the total mass of the diaphragm paper, the sizing layer locates outside of the first layer and the third layer and is made up of one surface treatment agent selected from the group consisting of polyethylene oxide (PEO), surfactants such as sodium dodecyl benzene sulfonate, wetting fluid etc.

4. A battery, wherein, having the diaphragm paper according to claim 1 as a diaphragm located between the positive electrode and the negative electrode.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is the structural diagram of an ultra-low concentration inclined wire machine used in the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

(2) The manufacturing methods and processes of the present invention will be described in detail hereinafter in conjunction with the accompanying drawings:

(3) As shown in FIG. 1, the present invention used an ultra-low concentration inclined wire machine to prepare the diaphragm. A is a pulp distributor of the inclined wire machine in this FIGURE, the pulp distributor A is divided into three layers which are mutually independent and expressed respectively in 1, 2, 3, in order that the pulp entering the pulp distributor will not mix. B is a rectifying zone of the inclined wire machine, the rectifying zone is also divided into three flow channels, which matches with layers 1, 2 and of the pulp distributor A. The function of the rectifying zone B is to rectify the pulp from the pulp distributor A, so as to generate a flow state of high intensity and micro-scale turbulence and no vortex is formed, thereby making the flow regime of the pulp stable, this can ensure that no blending occurs when the pulp in three layers are formed and good uniformity can be obtained. The pulp goes through the rectifying zone B and then arrives at the dewatering and forming zone C of the inclined wire machine, the pulp in three layers from the rectifying zone B are dewatered and formed at the dewatering and forming zone C by dewatering freely or dewatering under a certain vacuum. The pulp in the third layer arrives firstly at the dewatering forming zone C, so the pulp in the third layer is firstly dewatered and formed, followed by the pulp in the second layer, finally the pulp in the first layer, in such way the multi-layered paper having three-layer structure of the present invention can be formed once on the inclined wire machine. Since the paper-making process has a filling effect, i.e., after the previous layer is formed, larger holes may occur, the pulp at holes is little, so the resistance from the dewatering is small, the pulp in the second layer will select preferably to form at holes to make up for the defect of big holes, thereby ensuring the diaphragm will not appear more big holes. The forming time of the pulp in three layers is fairly short, the calculated value is less than 0.6 seconds, so the pulp in three layers will not mix, and there is no obvious layer interface, so that the multi-layered paper prepared both have the isolated layer and have the loose layer and the transition layer, and the interlayer bonding force is very good, there is no large shrinkage during use. The basis weight of each layer is controlled by adjusting precisely the concentrations and flow of the pulp in the 1, 2 and 3 layers. D is the multi-layer paper after forming uniformly, which is then squeezed to an appropriate dryness through the press section of the inclined wire machine, dried by a Yankee dryer or a multi-cylinder dryer, processed through a sizing treatment, then dried by a dryer, and then the surface of the diaphragm is treated by a calender, and finally is cut into the desired width by a dividing and cutting machine.

(4) Now the performance of the specific preferred embodiment of the diaphragm paper of the present invention is compared with that of the single-layer diaphragm paper.

EXAMPLES 1-5

Diaphragm Papers Used for Alkaline Batteries

(5) The composition and ratio of each layer in the diaphragm of examples 1-5 were shown in table 1. The raw materials were mixed with water in accordance with the formula, beated, diluted to 0.05% to obtain the pulp of the first layer, the second layer and the third layer. The pulp of the first layer was sent into flow channel 1, the pulp of the second layer was sent into flow channel 2, and the pulp of the third layer was sent into flow channel 3 by using the ultra-low concentration inclined wire machine shown in FIG. 1, once-forming was performed in accordance with the above-mentioned method to prepare the diaphragm papers of examples 1-5.

(6) TABLE-US-00001 TABLE 1 Raw material of examples 1-5 Examples First layer (wt %) Second layer (wt %) Third layer (wt %) 1 1. Hardwood pulp (25%) 1. Tencel fibrillated fiber 1. Hardwood pulp (30%) with a beating degree of (60%) with a beating with a beating degree of 11-30 SR and a fiber degree of 60-80 SR; 11-30 SR and a fiber length of 0.6-2 mm; 2. Superfine polyvinyl length of 0.6-2 mm; 2. Viscose fiber (10%) alcohol fiber (35%) with 2. Viscose fiber (15%) with a fineness of 0.9 a fineness of 0.5 dtex with a fineness of 0.5 dtex and a fiber length of and a fiber length of dtex and a fiber length of 3 mm; 2 mm; 3 mm; 3. Formalized polyvinyl 3. Water-soluble 3. Polyvinyl alcohol alcohol fiber (50%) with polyvinyl alcohol fiber fiber (40%) with a a fineness of 1.0 dtex (5%) with a fineness of fineness of 1.11 dtex and and a fiber length of 3 1.1 dtex, a fiber length a fiber length of 3 mm; mm; of 3 mm and a water 4. Water-soluble 4. Water-soluble soluble temperature of polyvinyl alcohol fiber polyvinyl alcohol fiber 70 C. (15%) with a fineness of (15%) with a fineness of 1.1 dtex, a fiber length 1.11 dtex, a fiber length of 3 mm, and a water of 3 mm and a water soluble temperature of soluble temperature of 70 C. 70 C. 2 1. Hardwood pulp (20%) 1. Tencel fibrillated fiber 1. Hardwood pulp (25%) with a beating degree of (55%) with a beating with a beating degree of 11-30 SR and a fiber degree of 60-80 SR; 11-30 SR and a fiber length of 0.6-2 mm; 2. Superfine polyvinyl length of 0.6-2 mm; 2. Viscose fiber (15%) alcohol fiber (40%) with 2. Viscose fiber (20%) with a fineness of 0.9 a fineness of 0.5 dtex with a fineness of 0.5 dtex and a fiber length of and a fiber length of dtex and a fiber length of 3 mm; 2 mm; 3 mm; 3. Formalized polyvinyl 3. Water-soluble 3. Polyvinyl alcohol alcohol fiber (50%) with polyvinyl alcohol fiber fiber (40%) with a a fineness of 1.0 dtex (5%) with a fineness of fineness of 1.11 dtex and and a fiber length of 3 1.1 dtex, a fiber length a fiber length of 3 mm; mm; of 3 mm, and a water 4. Water-soluble 4. Water-soluble soluble temperature of polyvinyl alcohol fiber polyvinyl alcohol fiber 70 C. (15%) with a fineness of (15%) with a fineness of 1.1 dtex, a fiber length 1.1 dtex, a fiber length of 3 mm and a water of 3 mm and a water soluble temperature of soluble temperature of 70 C. 70 C. 3 1. Hardwood pulp (20%) 1. Tencel fibrillated fiber 1. Hardwood pulp (25%) with a beating degree of (50%) with a beating with a beating degree of 11-30 SR and a fiber degree of 60-80 SR; 11-30 SR and a fiber length of 0.6-2 mm; 2. Superfine polyvinyl length of 0.6-2 mm; 2. Viscose fiber (15%) alcohol fiber (45%) with 2. Viscose fiber (20%) with a fineness of 0.9 a fineness of 0.5 dtex with a fineness of 0.5 dtex and a fiber length of and a fiber length of dtex and a fiber length of 3 mm; 2 mm; 3 mm; 3. Formalized polyvinyl 3. Water-soluble 3. Polyvinyl alcohol alcohol fiber (50%) with polyvinyl alcohol fiber fiber (40%) with a a fineness of 1.11 dtex (5%) with a fineness of fineness of 1.11 dtex and and a fiber length of 3 1.1 dtex, a fiber length a fiber length of 3 mm; mm; of 3 mm and a water 4. Water-soluble 4. Water-soluble soluble temperature of polyvinyl alcohol fiber polyvinyl alcohol fiber 70 C. (15%) with a fineness of (15%) with a fineness of 1.1 dtex, a fiber length 1.1 dtex, a fiber length of 3 mm and a water of 3 mm and a water soluble temperature of soluble temperature of 70 C. 70 C. 4 1. Hardwood pulp (20%) 1. Tencel fibrillated fiber 1. Hardwood pulp (25%) with a beating degree of (50%) with a beating with a beating degree of 11-30 SR and a fiber degree of 60-80 SR; 11-30 SR and a fiber length of 0.6-2 mm; 2. Superfine polyvinyl length of 0.6-2 mm; 2. Viscose fiber (15%) alcohol fiber (45%) with 2. Viscose fiber (20%) with a fineness of 0.9 a fineness of 0.5 dtex with a fineness of 0.5 dtex and a fiber length of and a fiber length of dtex and a fiber length of 3 mm; 2 mm; 3 mm; 3. Formalized polyvinyl 3. Water-soluble 3. Polyvinyl alcohol alcohol fiber (50%) with polyvinyl alcohol fiber fiber (40%) with a a fineness of 1.11 dtex (5%) with a fineness of fineness of 1.11 dtex and and a fiber length of 3 1.1 dtex, a fiber length a fiber length of 3 mm; mm; of 3 mm and a water 4. Water-soluble 4. Water-soluble soluble temperature of polyvinyl alcohol fiber polyvinyl alcohol fiber 70 C. (15%) with a fineness of (15%) with a fineness of 1.1 dtex, a fiber length 1.1 dtex, a fiber length of 3 mm and a water of 3 mm and a water soluble temperature of soluble temperature of 70 C. 70 C. 5 1. Hardwood pulp (20%) 1. Tencel fibrillated fiber 1. Hardwood pulp (25%) with a beating degree of (50%) with a beating with a beating degree of 11-30 SR and a fiber degree of 60-80 SR; 11-30 SR and a fiber length of 0.6-2 mm; 2. Superfine polyvinyl length of 0.6-2 mm; 2. Viscose fiber (15%) alcohol fiber (45%) with 2. Viscose fiber (20%) with a fineness of 0.9 a fineness of 0.5 dtex with a fineness of 0.5 dtex and a fiber length of and a fiber length of dtex and a fiber length of 3 mm; 2 mm; 3 mm; 3. Formalized polyvinyl 3. Water-soluble 3. Polyvinyl alcohol alcohol fiber (50%) with polyvinyl alcohol fiber fiber (40%) with a a fineness of 1.11 dtex (5%) with a fineness of fineness of 1.11 dtex and and a fiber length of 3 1.1 dtex, a fiber length a fiber length of 3 mm; mm; of 3 mm and a water 4. Water-soluble 4. Water-soluble soluble temperature of polyvinyl alcohol fiber polyvinyl alcohol fiber 70 C. (15%) with a fineness of (15%) with a fineness of 1.1 dtex, a fiber length 1.1 dtex, a fiber length of 3 mm and a water of 3 mm and a water soluble temperature of soluble temperature of 70 C. 70 C.

COMPARATIVE EXAMPLES 1-2

Diaphragm Papers Used for Single-Layer Alkaline Batteries

(7) The formula of the diaphragm paper used for single-layer alkaline batteries of comparative examples 1-2 were shown in table 2.

(8) The raw materials were mixed with water and beated in accordance with the formula and then made paper according to the conventional method for making paper to obtain the diaphragm paper used for single-layer alkaline batteries.

(9) TABLE-US-00002 TABLE 2 Raw materials of comparative examples 1-2 Comparative examples Single-layer structures 1 1. Hardwood pulp (30%) with a beating degree of 11-30 SR and a fiber length of 0.6-2 mm; 2. Viscose fiber (15%) with a fineness of 0.9 dtex and a fiber length of 3 mm; 3. Formalized polyvinyl alcohol fiber (40%) with a fineness of 1.11 dtex and a fiber length of 3 mm; 4. Water-soluble polyvinyl alcohol fiber (15%) with a fineness of 1.1 dtex, a fiber length of 3 mm and a water soluble temperature of 70 C. 2 1.Tencel fibrillated fiber (10%) with a beating degree of 60-80 SR; 2. Superfine polyvinyl alcohol fiber (40%) with a fineness of 1.1 dtex and a fiber length of 3 mm; 3. Water-soluble polyvinyl alcohol fiber (15%) with a fineness of 1.1 dtex, a fiber length of 3 mm and a water soluble temperature of 70 C.; 4. Hardwood pulp (35%) with a beating degree of 11-30 SR and a fiber length of 0.6-2 mm.

EXPERIMENTAL EXAMPLE

(10) The performance of the diaphragm papers prepared by examples 1-5 and comparative examples 1-2 were tested according to the following method.

(11) 1. Testing Items and Methods

(12) 1) Measurement of beating degree

(13) The measurement was conducted according to ISO5267/1 international standards.

(14) 2) Measurement of average fiber length

(15) The measurement was conducted by using FS300 fiber analyzer.

(16) 3) Measurement of thickness, basis weight and tensile

(17) The measurement was conducted according to Tappi standard.

(18) 4) Measurement of air permeability

(19) The measurement was conducted according to the textile testing method.

(20) 5) Measurement of pore size

(21) The measurement was conducted by using PMI pore size analyzer.

(22) 6) Measurement of liquid absorption rate

(23) A 50 mm50 mm square diaphragm paper with a mass after drying of W.sub.1 was taken and immersed in a 40% KOH solution for 10 minutes, one corner of the paper was fixed and suspended in an air for 2 minutes, then weighted (the mass was W.sub.2).
Liquid permeability(%)=(W.sub.2W.sub.1)/W.sub.1100

(24) The measurement was performed 5 times and the average value was taken.

(25) 7) Measurement of liquid absorption height

(26) A 15 mm200 mm diaphragm paper slip was taken and suspended. One side of the paper (5 mm) was immersed in a 40% KOH solution. After 10 minutes, the electrolyte penetration height was measured as the absorption rate of the diaphragm electrolyte.

(27) The measurement was performed 5 times and the average value was taken.

(28) 8) Measurement of shrinking rate

(29) A 100 mm100 mm square diaphragm paper was taken. The area of the square diaphragm paper was recorded as A.sub.1. The square diaphragm paper was immersed in a 40% KOH solution for 24 hours, and then taken out. The length and width of the square diaphragm paper were measured, the area of the square diaphragm paper after immersing was calculated as A.sub.2.
shrinking rate=(A.sub.1A.sub.2)/A.sub.1100%

(30) 2. Measurement Results

(31) All testing results of the diaphragm paper prepared by examples 1-5 were shown in table 3.

(32) TABLE-US-00003 TABLE 3 Testing results of the diaphragm papers prepared by examples 1-5 Examples 1 2 3 4 5 First Layer (g/m.sup.2) 10 12 14 10 18 Second Layer (g/m.sup.2) 3 5 8 8 8 Third Layer (g/m.sup.2) 12 13 14 18 10 Basis Weight (g/m.sup.2) 25 30 36 36 36 Thickness (m) 75 90 105 105 105 Average Pore Size (m) 11 9.5 7.6 7.6 7.6 Tensile Strength (KN) 1.8 2.1 2.6 2.6 2.6 Air Permeability (ml/s) 260 230 190 190 190 Liquid Absorption Rate (%) 740 750 740 740 740 Liquid Absorption Height (mm/ 62 64 68 68 68 10 min) Shrinking Rate (%) 2.0 2.0 2.0 2.0 2.0

(33) All testing results of the diaphragm paper prepared by comparative examples 1-2 were shown in table 4.

(34) TABLE-US-00004 TABLE 4 Testing results of the diaphragm papers prepared by comparative examples 1-2 Comparative Examples 1 2 Structure Single layer Single layer Basis Weight (g/m.sup.2) 36 36 Thickness (m) 110 100 Average Pore Size (m) 15 12 Tensile strength (KN) 2.4 2.5 Air Permeability (ml/s) 450 260 Liquid Absorption Rate (%) 770 580 Liquid Absorption Height (mm/10 min) 70 50 Shrinking Rate (%) 2.1 2.0

(35) 3. Conclusion

(36) The results show that the performance of the multi-layer diaphragm papers prepared by examples 1-5 are better when comparing with the single-layer diaphragm papers prepared by comparative examples 1-2. Specifically, the pore size is small, the average pore size is substantially less than 10 m, the tensile strength is good, the air permeability is good, the liquid absorption rate is large, and the shrinkage rate is small, all of which fully meet the requirement of diaphragm materials used for alkaline batteries.

EXAMPLES 6-10

Diaphragm Papers Used for Lithium Ion Batteries

(37) The formula of the diaphragm paper of examples 6-10 were shown in table 5.

(38) TABLE-US-00005 TABLE 5 Raw materials of examples 6-10 Examples First layer (wt %) Second layer (wt %) Third layer (wt %) 6 1. PP fiber (50%) with a 1. Para-Aramid 1. PP fiber (20%) with a fineness of 0.9 dtex and a fibrillated fiber (60%) fineness of 0.9 dtex and a length of 3 mm; with a beating degree of length of 3 mm; 2. PET fiber (50%) with 60-80 SR; 2. PET fiber (40%) with a fineness of 1.0 dtex and 2. Superfine PET fiber a fineness of 1.0 dtex and a fiber length of 3 mm; (40%) with a fineness of a length of 3 mm; 3. PE fiber (15%) with a 0.1 dtex and a length of 2 3. PE fiber (15%) with a fineness of 1.11 dtex and mm. fineness of 1.11 dtex and a fiber length of 3 mm. a length of 3 mm. 7 1. PP/PE composite fiber 1. PBO fibrillated fiber 1. PP fiber (20%) with a (100%) with a fineness (60%) with a beating fineness of 0.9 dtex and a of 0.9 dtex and a length degree of 60-80 SR; length of 3 mm; of 3 mm. 2. Superfine PET fiber 2. PET fiber (40%) with (40%) with a fineness of a fineness of 1.0 dtex and 0.1 dtex and a length of a length of 3 mm; 2 mm. 3. PE (15%) with a fineness of 1.11 dtex and a length of 3 mm. 8 1. PP/EVOH composite 1. PBO fibrillated fiber 1. PP/EVOH composite fiber (80%) with a (70%) with a beating fiber (80%) with a fineness of 0.9 dtex and a degree of 60-80 SR; fineness of 0.9 dtex and a length of 3 mm; 2. Superfine PP fiber length of 3 mm; 2. PE fiber (20%) with a (40%) with a fineness of 2. PE fiber (20%) with a fineness of 0.5 dtex and a 0.3 dtex and a length of 2 fineness of 0.5 dtex and a length of 3 mm. mm. length of 3 mm. 9 1. PP/EVOH composite 1. Tencel fibrillated fiber 1. PP/EVOH composite fiber (80%) with a (50%) with a beating fiber (80%) with a fineness of 0.9 dtex, degree of 60-80 SR; fineness of 0.9 dtex and a length of 3 mm; 2. PBO fiber fibrillated length of 3 mm; 2. PE fiber (20%) with a fiber (30%) with a 2. PE fiber (20%) with a fineness of 0.5 dtex and a beating degree of fineness of 0.5 dtex and a length of 3 mm. 70-90 SR; length of 3 mm. 3. Superfine PP fiber (20%) with a fineness of 0.3 dtex and a length of 2 mm. 10 1. PP fiber (10%) with a 1. Tencel fibrillated fiber 1. PP fiber (10%) with a fineness of 0.9 dtex and a (50%) with a beating fineness of 0.9 dtex and a length of 3 mm; degree of 60-80 SR; length of 3 mm; 2. PET fiber (50%) with 2. PBO fiber fibrillated 2. PET fiber (50%) with a fineness of 1.0 dtex and fiber (30%) with a a fineness of 1.0 dtex and a length of 3 mm; beating degree of a length of 3 mm; 3. PE fiber (15%) with a 70-90 SR; 3. PE (15%) with a fineness of 1.11 dtex and 3. Superfine PP fiber fineness of 1.11 dtex and a length of 3 mm. (20%) with a fineness of a length of 3 mm. 0.3 dtex and a length of 2 mm.

(39) The diaphragm papers used for lithium ion batteries were prepared according to the preparation method of examples 1-5 and the testing results were shown in table 6.

(40) TABLE-US-00006 TABLE 6 Testing results of the diaphragm papers prepared by examples 6-10 Examples 6 7 8 9 10 First Layer (g/m.sup.2) 8 10 13 15 20 Second Layer (g/m.sup.2) 4 5 4 8 10 Third Layer (g/m.sup.2) 8 10 13 17 20 Basis Weight (g/m.sup.2) 20 25 30 40 50 Thickness (m) 18 28 35 40 60 Average Pore Size (m) 5.0 6.2 7.6 8.1 7.7 Tensile Strength (KN) 1.8 2.2 2.6 2.7 2.5 Air Permeability (ml/s) 50 70 100 120 140 Liquid Absorption Rate (%) 320 370 420 500 520 Liquid Absorption Height 34 36 38 45 55 (mm/10 min) Shrinking Rate (%) 1.0 1.1 2.0 1.7 1.8

(41) The results show that the multi-layer diaphragm paper prepared by examples 6-10 have superior performance, wherein the pore size is small, the average pore size is less than 10 m, the tensile strength is good, the air permeability is good, the liquid absorption rate is large and the shrinkage rate is small, all of which fully meet the requirement of diaphragm materials used for lithium ion batteries.

EXAMPLE 11

A Alkaline Zinc Manganese Battery

(42) The diaphragm paper prepared by example 1 was tailored to an appropriate size, placed between the positive electrode material and the negative electrode material, the alkaline zinc manganese battery was prepared according to the conventional method for making alkaline zinc manganese batteries.

EXAMPLE 12

A Lithium Ion Battery

(43) The diaphragm paper prepared by example 6 was to tailored an appropriate size, placed between the positive electrode material and the negative electrode material, the lithium ion battery was prepared according to the conventional method for making lithium ion batteries.