Alkaline battery diaphragm with composite nano protective layer

Abstract

The utility model provides an alkaline battery diaphragm with a composite nano protective layer, and belongs to the technical field of alkaline batteries. The utility model provides an alkaline battery diaphragm with a composite nano protective layer, which comprises an outer layer (1), a middle layer (2) and an inner layer (3) which are sequentially laminated, the outer layer (1) is a nano cellulose-nano calcium carbonate mixed layer, the middle layer (2) comprises regenerated cellulose fiber (6) and a penetrating agent (7) loaded on the surface of the regenerated cellulose fiber, and the inner layer (3) is a nano calcium carbonate mixed layer. And the inner layer (3) is made of vinylon fibers (8). In the utility model, the outer layer is an ion migration regulation and control layer, the middle layer is a liquid absorption and storage layer, and the inner layer is an alkali-resistant layer. According to the diaphragm, the multilayer structure design is adopted, the homogenization effect of pores modified by nanoparticles on ion migration is utilized, the selectivity of zinc deposition is realized, the alkali resistance is good, the liquid absorption and storage are controllable, the safety of a battery is improved, and the cycle life of the battery is prolonged.

Description

Technical Field

[0001] The utility model relates to the technical field of alkaline batteries, in particular to a composite nano-protective layer alkaline battery separator. Background Art

[0002] At present, the portability and diversification of electrical appliances have made high energy density and high current discharge the future development direction of alkaline manganese batteries, which also puts forward higher requirements for the safety of battery materials including separators. The main function of the separator in the battery is to isolate the positive and negative active materials of the battery to prevent internal short circuit of the battery caused by direct contact of the two polar active materials. However, it allows the free passage of electrolyte ions. The pore diameter of the commonly used alkaline battery separators on the market is 5-10 μm, but the distribution is relatively wide, and the maximum pore diameter exceeds 30 μm. This is because these separators are formed by fiber interweaving, and the pore structure and pore diameter cannot be controlled, resulting in uneven ion migration. Ion migration mainly concentrates in places with large pore diameter and small equivalent internal resistance. In places with small pore diameter, the ion migration rate is slow, and the battery performance declines. When the pore diameter is large enough, self-discharge and even short circuit phenomena will occur. In addition, the uneven pore diameter will also cause uneven zinc deposition, resulting in abnormal growth of zinc on the separator and damage to the separator. Therefore, the adjustment of the pore diameter of the separator is very important for the safety of the battery. Therefore, it is necessary to provide an alkaline battery separator with uniform pores, good alkali resistance, controllable liquid absorption and storage, and especially excellent safety performance. Summary of the Utility Model

[0003] In view of this, the purpose of the utility model is to provide a composite nano-protective layer alkaline battery separator. The composite nano-protective layer alkaline battery separator provided by the utility model has uniform pores, good alkali resistance, controllable liquid absorption and storage, and excellent safety performance.

[0004] In order to achieve the above-mentioned utility model purpose, the utility model provides the following technical solutions:

[0005] The utility model provides a composite nano-protective layer alkaline battery separator, which comprises an outer layer 1, an intermediate layer 2 and an inner layer 3 arranged in a stacked manner in sequence. The outer layer 1 is a nano-cellulose-nano-calcium carbonate mixed layer, and the nano-cellulose-nano-calcium carbonate mixed layer comprises nano-cellulose 5 and nano-calcium carbonate 4. The intermediate layer 2 comprises regenerated cellulose fibers 6 and a penetrant 7 loaded on the surface of the regenerated cellulose fibers. The inner layer 3 is vinylon fiber 8.

[0006] Preferably, the thickness of the outer layer 1 is 1-15 μm, the thickness of the intermediate layer 2 is 20-55 μm, and the thickness of the inner layer 3 is 30-70 μm.

[0007] Preferably, the diameter of the nano-cellulose 5 is 20-100 nm, and the particle size of the nano-calcium carbonate 4 is 50-200 nm.

[0008] Preferably, the nano-cellulose / nano-calcium carbonate hybrid layer is prepared by a method including the following steps:

[0009] Mix and grind regenerated cellulose fibers with calcium hydroxide, then introduce carbon dioxide to carry out a precipitation reaction, and in-situ grow nano-calcium carbonate on the cellulose to obtain the nano-cellulose / nano-calcium carbonate hybrid layer.

[0010] Preferably, the mass of the calcium hydroxide is 10% - 50% of the mass of the cellulose.

[0011] Preferably, the penetrant 7 includes a non-ionic surfactant.

[0012] Preferably, the mass ratio of the regenerated cellulose fibers 6 to the penetrant 7 is 55:0.5 - 5.

[0013] Preferably, the fiber length of the vinylon fiber 8 is 2 - 6 mm, the fiber linear density is 0.6 - 2.0 dtex, and the acetalization ratio is 30% - 40%.

[0014] Preferably, the grammage of the composite nano-protective layer alkaline battery separator is 30 - 48 g / m 2 , and the grammage of the outer layer 1 is 2 - 10 g / m 2 , and the grammage of the middle layer 2 is 10 - 25 g / m 2 , and the grammage of the inner layer 3 is preferably 10 - 25 g / m 2 .

[0015] Preferably, the porosity of the composite nano-protective layer alkaline battery separator is 50% - 75%, the average pore diameter is 3 - 8 μm, and the maximum pore diameter is 15 - 25 μm.

[0016] The present utility model provides a composite nano-protective layer alkaline battery separator, which includes an outer layer 1, a middle layer 2 and an inner layer 3 that are sequentially stacked. The outer layer 1 is a nano-cellulose / nano-calcium carbonate hybrid layer, the nano-cellulose / nano-calcium carbonate hybrid layer includes nano-cellulose 5 and nano-calcium carbonate 4, the middle layer 2 includes regenerated cellulose fibers 6 and a penetrant 7 loaded on the surface of the regenerated cellulose fibers, and the inner layer 3 is a vinylon fiber 8.

[0017] Compared with the prior art, the beneficial effects of the present utility model are as follows:

[0018] In the present utility model, the outer layer 1 is an ion migration regulation layer, the middle layer 2 is a liquid absorption and storage layer, and the inner layer is an alkali-resistant layer. The outer layer 1 is a nano-cellulose - nano-calcium carbonate mixed layer. Nano-calcium carbonate 4 grows on nano-cellulose 5 without falling off and is extremely evenly distributed. The pore size of the separator is jointly regulated by nano-cellulose 5 and nano-calcium carbonate 4, making full use of the homogenizing effect of the pores modified by nano-calcium carbonate 4 on ion migration, realizing the regulation of the ion migration rate in the electrolyte, and achieving the selectivity of zinc deposition. Moreover, nano-cellulose 5 itself has good film-forming properties, and no adhesive needs to be added. There is a hydrogen bond interaction between nano-cellulose 5 and the regenerated cellulose fiber 6 in the middle layer 2, and the bonding strength is relatively good. The presence of nano-calcium carbonate 4 will also greatly improve the heat resistance of the separator. Due to the existence of the nano-cellulose - nano-calcium carbonate mixed layer, there is no need to use fibers with short length, low linear density, and extremely high cost, which brings convenience to the dispersion of fibers in the preparation process; the pore sizes of each layer are different, thus improving the liquid absorption capacity, further reducing the internal resistance, and because the pores of each layer do not penetrate, the electrolyte retention capacity is improved, and the ion conductivity of the separator is enhanced; the multi-layer composite separator has relatively high mechanical strength; the regenerated cellulose fiber layer is the middle liquid absorption and storage layer, and the vinylon fiber layer is used as the alkali-resistant inner layer, thus meeting the requirement of long battery working time and significantly improving the working time of the battery.

[0019] Furthermore, the middle layer 2 can better regulate the liquid absorption amount and liquid absorption speed of the separator by controlling the beating degree of the regenerated cellulose fiber 6 and the addition amount of the penetrant 7. The reason is that the electrolyte injection amount of alkaline batteries of the same model is certain. If the liquid absorption amount of the separator is too large or the liquid absorption speed is too fast, it will lead to a small liquid absorption amount of the electrode. If the liquid absorption amount of the separator is too small, the battery performance will be affected, and if the liquid absorption speed is too slow, the electrolyte will not have enough time to penetrate the separator.

[0020] Furthermore, the raw material for preparing nano-cellulose 5 is regenerated cellulose fiber, which has good alkali resistance itself. Coupled with the alkaline environment (pH value is 11 - 13) provided by calcium hydroxide, further alkali treatment of cellulose greatly improves the alkali resistance of the nano-cellulose - nano-calcium carbonate mixed layer and the separator.

[0021] In summary, through the multi-layer structure design, the composite nano-protective layer alkaline battery separator of the present utility model realizes the regulation of the pore size of the alkaline battery separator, the homogenizing effect on ion migration, and further realizes the selectivity of zinc deposition, has good alkali resistance, controllable liquid absorption and storage, and improves the safety and cycle life of the battery. Description of the Drawings

[0022] Figure 1Schematic structural diagram of the alkaline battery separator with a composite nano protective layer provided by the present utility model, where 1 - outer layer, 2 - intermediate layer, 3 - inner layer, 4 - nano calcium carbonate, 5 - nano cellulose, 6 - regenerated cellulose fiber, 7 - penetrant, 8 - vinylon fiber. Detailed implementation manners

[0023] The present utility model provides an alkaline battery separator with a composite nano protective layer, which includes an outer layer 1, an intermediate layer 2, and an inner layer 3 that are sequentially stacked. The outer layer 1 is a nano cellulose - nano calcium carbonate mixed layer, and the nano cellulose - nano calcium carbonate mixed layer includes nano cellulose 5 and nano calcium carbonate 4. The intermediate layer 2 includes regenerated cellulose fiber 6 and a penetrant 7 loaded on the surface of the regenerated cellulose fiber. The inner layer 3 is vinylon fiber 8.

[0024] In a specific embodiment of the present utility model, the grammage of the alkaline battery separator with a composite nano protective layer is preferably 30 - 48 g / m 2 , the grammage of the outer layer 1 is preferably 2 - 10 g / m 2 , the grammage of the intermediate layer 2 is preferably 10 - 25 g / m 2 , the grammage of the inner layer 3 is preferably 10 - 25 g / m 2 .

[0025] In a specific embodiment of the present utility model, the porosity of the alkaline battery separator with a composite nano protective layer is preferably 50 - 75%, more preferably 55 - 70%, the average pore diameter is preferably 3 - 8 μm, and the maximum pore diameter is preferably 15 - 25 μm.

[0026] In a specific embodiment of the present utility model, the thickness of the alkaline battery separator with a composite nano protective layer is preferably 50 - 140 μm.

[0027] Figure 1 Schematic structural diagram of the alkaline battery separator with a composite nano protective layer provided by the present utility model, where 1 - outer layer, 2 - intermediate layer, 3 - inner layer, 4 - nano calcium carbonate, 5 - nano cellulose, 6 - regenerated cellulose fiber, 7 - penetrant, 8 - vinylon fiber. The following is an explanation of the alkaline battery separator with a composite nano protective layer of the present utility model in conjunction with Figure 1 to explain the alkaline battery separator with a composite nano protective layer of the present utility model.

[0028] In a specific embodiment of the present utility model, the thickness of the outer layer 1 is preferably 1 - 15 μm, more preferably 5 - 10 μm, and the outer layer 1 serves as an ion migration regulation layer.

[0029] In a specific embodiment of the present utility model, the diameter of the nano cellulose 5 is preferably 20 - 100 nm, and the particle size of the nano calcium carbonate 4 is preferably 50 - 200 nm.

[0030] In a specific embodiment of the present utility model, the nano-cellulose - nano-calcium carbonate hybrid layer is preferably prepared by a method comprising the following steps:

[0031] Mix the regenerated cellulose fibers with calcium hydroxide, grind them, and then introduce carbon dioxide for precipitation reaction to in-situ grow nano-calcium carbonate on the cellulose to obtain the nano-cellulose - nano-calcium carbonate hybrid layer.

[0032] In a specific embodiment of the present utility model, the mass of the calcium hydroxide is preferably 10% - 50% of the mass of the cellulose, more preferably 30%. If it is lower than 10%, the grown calcium carbonate will be unevenly distributed, and if it is higher than 50%, accumulation may occur.

[0033] The present utility model has no special limitation on the source of the regenerated cellulose fibers, and any source well-known to those skilled in the art can be used.

[0034] In a specific embodiment of the present utility model, the thickness of the intermediate layer 2 is preferably 20 - 55 μm, more preferably 30 - 50 μm. The intermediate layer 2 serves as a liquid absorption and storage layer; the average pore size of the intermediate layer 2 is preferably 5 - 20 μm, the maximum pore size is preferably less than 35 μm, and the porosity is preferably 60 - 75%.

[0035] In a specific embodiment of the present utility model, the liquid absorption amount of the intermediate layer 2 is preferably 300% - 500%, and the liquid absorption speed is preferably 10 - 40 mm / 180 s, more preferably 18 - 35 mm / 180 s. The liquid absorption amount refers to the ratio of the mass of the absorbed solution to the mass of the intermediate layer 2.

[0036] In a specific embodiment of the present utility model, the length of the regenerated cellulose fibers 6 is preferably 2 - 6 mm, and the linear density is preferably 0.6 - 2.0 dtex.

[0037] The present utility model has no special limitation on the source of the regenerated cellulose fibers 6, and any source well-known to those skilled in the art can be used.

[0038] In a specific embodiment of the present utility model, the penetrant 7 preferably comprises a non-ionic surfactant, more preferably the non-ionic 31762 surfactant, non-ionic 31731 surfactant or non-ionic 31750 surfactant of Henan Daochun New Material Technology Co., Ltd.; the penetrant 7 has excellent wetting and permeability and good alkali stability, and its function is to improve the liquid absorption speed and liquid absorption amount of the intermediate layer 2.

[0039] In a specific embodiment of the present utility model, the mass ratio of the regenerated cellulose fibers 6 to the penetrant 7 is preferably 55:0.5 - 5, more preferably 55:2.

[0040] In a specific embodiment of the present utility model, the thickness of the inner layer 3 is preferably 30 - 70 μm, more preferably 40 - 60 μm. The inner layer 3 serves as an alkali-resistant layer. The average pore diameter of the inner layer 3 is preferably 5 - 20 μm, the maximum pore diameter is preferably less than 35 μm, and the porosity is preferably 65 - 80%.

[0041] In a specific embodiment of the present utility model, the fiber length of the vinylon fiber 8 is preferably 2 - 6 mm, the fiber linear density is preferably 0.6 - 2.0 dtex, and the acetalization ratio is preferably 30% - 40%. The acetalization ratio represents the stability of the vinylon fiber. The larger the ratio, the better the stability.

[0042] The present utility model also provides a method for preparing the composite nano-protective layer alkaline battery separator described in the above technical solution, comprising the following steps:

[0043] Providing a regenerated cellulose fiber slurry and a vinylon fiber slurry; the regenerated cellulose fiber slurry contains a penetrant 7;

[0044] Mixing regenerated cellulose fibers, calcium hydroxide, and water to obtain a cellulose-calcium hydroxide mixture;

[0045] Grinding the cellulose-calcium hydroxide mixture to obtain a nano-cellulose-calcium hydroxide mixture;

[0046] Passing carbon dioxide into the nano-cellulose-calcium hydroxide mixture until the pH value is neutral to obtain a nano-cellulose-nano-calcium carbonate mixture;

[0047] Shaping the vinylon fiber slurry and the regenerated cellulose fiber slurry respectively to form the inner layer 3 and the intermediate layer 2. After compounding, a separator precursor is obtained;

[0048] Coating the surface of the separator precursor with the nano-cellulose-nano-calcium carbonate mixture and then drying to form the outer layer 1, thereby obtaining the composite nano-protective layer alkaline battery separator.

[0049] In the present utility model, unless otherwise specified, the raw materials used are commercially available products in the art.

[0050] The present utility model provides a regenerated cellulose fiber slurry and a vinylon fiber slurry; the regenerated cellulose fiber slurry contains a penetrant 7.

[0051] In a specific embodiment of the present utility model, the regenerated cellulose fiber slurry is preferably prepared by a method including the following steps: Pour 55-65 parts by weight of regenerated cellulose fibers into a hydraulic pulper, add water to dilute to a concentration of 2%-3%, defibrate for 15-30 min, then transport to a refiner for refining treatment, with the beating degree of 11-35°SR (more preferably 20°SR), then add water to dilute to a concentration of 0.05%-0.1%, and finally add 0.5-5 parts by mass of penetrant 7, and introduce it into the pre-machine tank for standby.

[0052] In a specific embodiment of the present utility model, the vinylon fiber slurry is preferably prepared by a method including the following steps: Pour 35-45 parts by weight of vinylon fibers into a hydraulic pulper, add water to dilute to a concentration of 1%-2%, defibrate for 15-30 min, then add water to dilute to a concentration of 0.05%-0.1%, and introduce it into the pre-machine tank for standby.

[0053] The present utility model mixes regenerated cellulose fibers, calcium hydroxide and water to obtain a cellulose-calcium hydroxide mixture.

[0054] The present utility model preferably places the regenerated cellulose fibers in a tank, adds water to dilute, then adds calcium hydroxide, and then adds water to dilute to a solid content of 2%-4%, and stirs evenly to obtain the cellulose-calcium hydroxide mixture.

[0055] After obtaining the cellulose-calcium hydroxide mixture, the present utility model grinds the cellulose-calcium hydroxide mixture to obtain a nano-cellulose-calcium hydroxide mixture.

[0056] In the present utility model, the grinding is preferably carried out in a homogenizer. The present utility model preferably measures the fiber size once every hour until the nano-level is obtained.

[0057] After obtaining the nano-cellulose-calcium hydroxide mixture, the present utility model passes carbon dioxide into the nano-cellulose-calcium hydroxide mixture until the pH value is neutral to obtain a nano-cellulose-nano-calcium carbonate mixture.

[0058] After obtaining the regenerated cellulose fiber slurry, vinylon fiber slurry and nano-cellulose-calcium hydroxide mixture, the present utility model forms the vinylon fiber slurry and the regenerated cellulose fiber slurry respectively to form the inner layer 3 and the intermediate layer 2. After lamination, a diaphragm precursor is obtained; after coating the surface of the diaphragm precursor with the nano-cellulose-nano-calcium carbonate mixture, it is dried to form the outer layer 1, and the composite nano-protective layer alkaline battery diaphragm is obtained.

[0059] The present utility model is preferably used on a twin-wire former. The cylinder A transfers the vinylon fiber slurry evenly onto the felt by means of rotary dewatering. When the felt passes through the cylinder B, the cylinder B also transfers the regenerated cellulose fiber slurry onto the felt with vinylon fibers by means of rotary dewatering. Through combination by a squeezing roller and drying, the diaphragm precursor is obtained. The diaphragm precursor passes through a coater and is coated with the nano-mixture, namely, the nano-cellulose - nano-calcium carbonate mixture, and then dried and formed to obtain the composite nano-protective layer alkaline battery diaphragm.

[0060] The present utility model also provides an application of the composite nano-protective layer alkaline battery diaphragm described in the above technical solution in the field of alkaline batteries.

[0061] Next, the technical solutions in the present utility model will be clearly and completely described in conjunction with the embodiments in the present utility model. Obviously, the described embodiments are only a part of the embodiments of the present utility model, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present utility model without making creative efforts shall fall within the protection scope of the present utility model.

[0062] The test standards in the embodiments of the present utility model are as follows:

[0063] Grammage: GB / T 451.2 - 2002; Air permeability: GB / T 5453 - 2012; Average pore size, maximum pore size: ASTM F316 - 2003; Porosity: GBT 40401 - 2021; Liquid absorption speed: SJ / T 10171 - 2016; Liquid storage capacity: QB / T 4173 - 2011; Beat degree: GB / T 3332 - 2004; Temperature-resistant shrinkage: Cut out a 100 mm × 100 mm diaphragm square, place it in an oven at 180 °C and dry for 4 h, take it out and measure the size change after cooling; Alkaline resistance loss rate: QB / T 4173 - 2011.

[0064] The penetrant used in the embodiments and comparative examples of the present utility model is the non-ionic 31762 surfactant of Henan Daochun New Material Technology Co., Ltd.

[0065] Examples 1 - 5

[0066] Change the grammage of the outer layer 1

[0067] Preparation method of the composite nano-protective layer alkaline battery diaphragm:

[0068] 1. Preparation of regenerated cellulose fiber slurry (intermediate layer slurry): Pour 55 parts by weight of regenerated cellulose fibers into a hydraulic pulper, dilute with water to a concentration of 2%, defibrate for 20 min, then transfer to a refiner for refining treatment, with the beating degree of 20°SR, dilute with water to 0.08%, add 2 parts by mass of penetrant, and introduce it into the pre-tank 2 for standby;

[0069] 2. Preparation of vinylon fiber slurry (inner layer slurry): Pour 40 parts by weight of vinylon fibers into a hydraulic pulper, dilute with water to a concentration of 1%, defibrate for 20 min, dilute with water to 0.08%, and introduce it into the pre-tank 1 for standby;

[0070] 3. Preparation of nano-cellulose - calcium carbonate mixture (outer layer raw material): Place different mass parts of regenerated cellulose fibers in a tank, dilute with water, then add calcium hydroxide powder (calcium hydroxide accounts for 50% of the mass of regenerated cellulose fibers), and then add water to dilute to a solid content of 3%, stir evenly to obtain a cellulose - calcium hydroxide mixture, pour it into a homogenizer for grinding, measure the fiber size every hour until it reaches the nanometer level. Export the ground mixture to a tank, introduce carbon dioxide into the mixture until the pH value is neutral to obtain a nano-cellulose - nano-calcium carbonate mixture. The average diameter of the ground nano-cellulose is 75 nm, and the average diameter of the generated calcium carbonate is 108 nm.

[0071] 4. On a twin-wire former, the cylinder A of the cylinder net transfers the vinylon fiber slurry evenly onto the felt by means of rotary dewatering. When the felt passes through the cylinder B of the cylinder net, the cylinder B of the cylinder net also transfers the regenerated cellulose fiber slurry onto the felt with vinylon fibers by means of rotary dewatering. Through the combination of extrusion rollers, drying, passing through a coater, coating with the nano-cellulose - nano-calcium carbonate mixture, and drying and forming, a composite nano-protective layer alkaline battery separator is obtained.

[0072] Comparative Example 1

[0073] Same as Example 1, the only difference is that the outer layer 1 is not coated (i.e., the grammage of the outer layer 1 is 0), and the total grammage is 41.5 g / m 2 。

[0074] Table 1 shows the test results of the battery separators obtained in Examples 1 - 5 and Comparative Example 1. It can be seen that from Example 1 to Example 5, both the average pore size and the maximum pore size have a relatively obvious decrease, that is, the distribution is more uniform, but the porosity changes little.

[0075] Table 1 Test results of the battery separators obtained in Examples 1 - 5 and Comparative Example 1

[0076] Example 1 Example 2 Example 3 Example 4 Example 5 Comparative Example 1 <![CDATA[Outer layer weight g / m 2 > 2.2 3.9 4.6 5.8 9.4 0 <![CDATA[Air permeability L / m 2 ·s]]> 43.6 24.5 18.7 18.6 2.8 69.5 Average pore size μm 5.38 5.17 5.20 4.18 3.92 5.65 Maximum pore size μm 21.39 20.01 19.87 17.12 15.44 24.74 Porosity % 71.12 70.43 70.78 69.61 65.33 73.48

[0077] Examples 6 - 10

[0078] Changing the beating degree of regenerated cellulose fiber and the dosage of penetrant

[0079] 1. Pour 55 parts by weight of regenerated cellulose fiber into a hydraulic pulper, dilute it with water to a concentration of 2%, defiberate for 20 min, then transfer it to a refiner for refining treatment. The beating degree is 11 - 40°SR, dilute it with water to 0.08%, add 0.5 - 5 parts by mass of penetrant, and introduce it into the pre-machine tank 2 for standby;

[0080] 2. Pour 40 parts by weight of vinylon fiber into a hydraulic pulper, dilute it with water to a concentration of 1%, defiberate for 20 min, dilute it with water to 0.08%, and introduce it into the pre-machine tank 1 for standby;

[0081] 3. Take a certain amount of regenerated cellulose fiber and place it in a tank, dilute it with an appropriate amount of water, then add calcium hydroxide powder (calcium hydroxide accounts for 50% of the mass of cellulose fiber), and then add water to dilute to a solid content of 3%. Stir evenly to obtain a cellulose-calcium hydroxide mixture. Slowly pour it into a homogenizer for grinding, measure the fiber size every hour until it reaches the nanometer level. Export the ground mixture to the tank, and pass carbon dioxide into the mixture until the pH value is neutral. Obtain a nano-cellulose-nano-calcium carbonate mixture. The average diameter of the ground nano-cellulose is 75 nm, and the average diameter of the generated calcium carbonate is 108 nm.

[0082] 4. On a twin-wire former, the round wire cage A evenly transfers the vinylon fiber to the felt by means of rotary dewatering. When the felt passes through the round wire cage B, the round wire cage B also transfers the regenerated cellulose fiber slurry to the felt with vinylon fiber by means of rotary dewatering. Combine through a squeeze roll, dry, pass through a coater, coat with the nano-mixture, and dry and form. The basis weight of the diaphragm is 45 - 47 g / m 2 , where the basis weight of the outer layer 1 is 4 - 5 g / m 2 .

[0083] Table 2 shows the preparation parameters of Examples 3, 6 - 10 and the test results of the diaphragm.

[0084] Table 2 Preparation parameters of Examples 3, 6 - 10 and the test results of the diaphragm

[0085]

[0086]

[0087] Comparative Examples 2 - 6

[0088] 1. Pour 55 parts by weight of regenerated cellulose fiber into a hydraulic pulper, add water to dilute it to a concentration of 2%, defiberate for 20 min, then transport it to a refiner for refining treatment, with the beating degree of 11 - 45°SR, add water to dilute it to 0.08%, add 0.5 - 5 parts by mass of penetrant, and introduce it into storage tank 2 for standby;

[0089] 2. Pour 40 parts by weight of vinylon fiber into a hydraulic pulper, add water to dilute it to a concentration of 1%, defiberate for 20 min, add water to dilute it to 0.08%, and introduce it into storage tank 1. Introduce the slurries in storage tank 2 and storage tank 1 into storage tank 3 and mix them to obtain a mixed fiber slurry;

[0090] 3. Take a certain amount of regenerated cellulose fiber and place it in a tank, add appropriate amount of water to dilute it, then add calcium hydroxide powder (calcium hydroxide accounts for 50% of the mass of cellulose fiber), and then add water to dilute it to a solid content of 3%, stir evenly to obtain a cellulose - calcium hydroxide mixture, slowly pour it into a homogenizer for grinding, measure the fiber size every hour until it reaches the nanometer level. Export the ground mixture to the tank, and introduce carbon dioxide into the mixture until the pH value is neutral. Obtain a nano - cellulose - nano - calcium carbonate mixture. The average diameter of the ground nano - cellulose is 75 nm, and the average diameter of the generated calcium carbonate is 108 nm.

[0091] 4. Double - wire former, but do not use cylinder B. Cylinder A evenly transfers the mixed fiber slurry to the felt by means of rotary dewatering, dries it, passes through a coater, coats it with the nano - mixture, and dries and forms it. The basis weight of the diaphragm is 45 - 47 g / m 2 and the basis weight of the outer layer, i.e., the nano - cellulose - calcium carbonate mixed layer, is 4 - 5 g / m 2 .

[0092] Table 3 shows the preparation parameters of Example 3, Comparative Examples 2 - 6 and the test results of the diaphragm.

[0093] Table 3 Preparation Parameters of Example 3, Comparative Examples 2 - 6 and the Test Results of the Diaphragm

[0094] Example 3 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 Degree of beating °SR 20 20 11 45 20 20 Dosage of penetrant 2 2 2 2 0.5 5 Liquid absorption rate mm / 180s 19 16 25 5 12 16 Liquid storage capacity % 473 410 434 305 356 448

[0095] Examples 11 - 13

[0096] Change the dosage of calcium hydroxide

[0097] 1. Pour 55 parts by weight of regenerated cellulose fiber into a hydraulic pulper, add water to dilute it to a concentration of 2%, defiberate for 20 min, then transport it to a refiner for refining treatment, with the beating degree of 20°SR, add water to dilute it to 0.08%, add 2 parts of penetrant, and introduce it into the pre - machine tank 2 for standby;

[0098] 2. Pour 40 parts by weight of vinylon fibers into a hydrapulper, add water to dilute to a concentration of 1%, defiberate for 20 min, then add water to dilute to 0.08%, and introduce it into the tank in front of the machine for standby;

[0099] 3. Take a certain amount of regenerated cellulose fibers and place them in a tank. Dilute with an appropriate amount of water, then add calcium hydroxide powder (calcium hydroxide accounts for 10% - 100% of the mass of cellulose fibers), and then add water to dilute to a solid content of 3%. Stir evenly to obtain a cellulose-calcium hydroxide mixture. Slowly pour it into a homogenizer for grinding. Measure the fiber size every hour until it reaches the nanometer level. Export the ground mixture to the tank, and pass carbon dioxide into the mixture until the pH value is neutral. Obtain a nano-cellulose-nano-calcium carbonate mixture.

[0100] 4. On a twin-wire former, the round wire cage A uniformly transfers the vinylon fibers to the felt by means of rotary dewatering. When the felt passes through the round wire cage B, the round wire cage B also transfers the regenerated cellulose fiber slurry to the felt with vinylon fibers by means of rotary dewatering. Combine through a squeezing roller, dry, pass through a coater, coat with the nano-mixture, and dry and form. The basis weight of the separator is 45 - 47 g / m 2 , and the basis weight of the outer layer, namely the nano-cellulose-calcium carbonate mixed layer, is 4 - 5 g / m 2 .

[0101] Table 4 shows the preparation parameters of Examples 3, 11 - 14 and Comparative Example 1 and the test results of the separator.

[0102] Table 4 Preparation Parameters of Examples 3, 11 - 14 and Comparative Example 1 and Test Results of the Separator

[0103] Example 3 Example 11 Example 12 Example 13 Example 14 Comparative Example 1 Dosage of calcium hydroxide, % 50 10 30 75 100 - Diameter of nanocellulose, nm 75 84 82 59 37 - Particle size of calcium carbonate, nm 108 172 133 136 201 - Temperature-resistant expansion and contraction, % 0 0.75 0 0 0 1.0 Alkali-resistant loss rate, % 3.9 5.1 4.4 3.1 3.2 8.2

[0104] Application Example

[0105] Assemble the separators prepared in Example 3 and Comparative Example 1 into alkaline manganese batteries, and test the open circuit voltage and internal resistance of the batteries at room temperature and 71 °C respectively. The results are shown in Table 5. It can be seen that when using the separator of the present invention, the open circuit voltage of the battery is significantly higher than that of Comparative Example 1, and the internal resistance is close.

[0106] Table 5 Open Circuit Voltage and Internal Resistance of Alkaline Manganese Batteries

[0107]

[0108] In summary, the conclusions obtained are shown in Table 6.

[0109] Table 6 Performance Advantages of the Present Invention

[0110]

[0111] The above description is only the preferred embodiment of the present utility model and does not impose any formal restrictions on the present utility model. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present utility model, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present utility model.

Claims

1. A composite nano protective layer alkaline battery separator, characterized in that: The invention comprises an outer layer (1), an intermediate layer (2) and an inner layer (3) which are stacked in sequence, wherein the outer layer (1) is a nanocellulose-nanocalcium carbonate mixed layer, the nanocellulose-nanocalcium carbonate mixed layer comprises nanocellulose (5) and nanocalcium carbonate (4), the intermediate layer (2) comprises regenerated cellulose fibers (6) and a penetrant (7) loaded on the surface of the regenerated cellulose fibers, and the inner layer (3) is vinylon fibers (8).

2. The composite nano protective layer alkaline battery separator according to claim 1, characterized in that: The thickness of the outer layer (1) is 1 to 15 μm, the thickness of the middle layer (2) is 20 to 55 μm, and the thickness of the inner layer (3) is 30 to 70 μm.

3. The composite nano protective layer alkaline battery separator according to claim 1, characterized in that: The diameter of the nanocellulose (5) is 20 to 100 nm, and the particle size of the nano calcium carbonate (4) is 50 to 200 nm.

4. The composite nano protective layer alkaline battery separator according to claim 1 or 3, characterized in that: The nanocellulose-nano calcium carbonate mixed layer is prepared by a method comprising the following steps: The regenerated cellulose fibers and calcium hydroxide are mixed and ground, and then carbon dioxide is introduced to perform a precipitation reaction, so that nano-calcium carbonate is grown in situ on the cellulose to obtain the nano-cellulose-nano-calcium carbonate mixed layer.

5. The composite nano protective layer alkaline battery separator according to claim 4, characterized in that: The mass of the calcium hydroxide is 10% to 50% of the mass of the cellulose.

6. The composite nano protective layer alkaline battery separator according to claim 1, characterized in that: The penetrant (7) includes a non-ionic surfactant.

7. The composite nano protective layer alkaline battery separator according to claim 1 or 6, characterized in that: The mass ratio of the regenerated cellulose fiber (6) to the penetrant (7) is 55:0.5-5.

8. The composite nano protective layer alkaline battery separator according to claim 1, characterized in that: The fiber length of the vinylon fiber (8) is 2 to 6 mm, the fiber linear density is 0.6 to 2.0 dtex, and the acetalization ratio is 30% to 40%.

9. The composite nano protective layer alkaline battery separator according to claim 1, characterized in that: The composite nano protective layer alkaline battery separator has a gram weight of 30 to 48 g / m 2 The outer layer (1) has a gram weight of 2 to 10 g / m 2 The weight of the intermediate layer (2) is 10 to 25 g / m 2 The weight of the inner layer (3) is 10 to 25 g / m 2 .

10. The composite nano protective layer alkaline battery separator according to claim 1, characterized in that: The composite nanometer protective layer alkaline battery separator has a porosity of 50-75%, an average pore size of 3-8 μm, and a maximum pore size of 15-25 μm.

Images