Zinc secondary battery

Abstract

To provide a zinc secondary battery improved in cycle characteristic.SOLUTION: A zinc secondary battery disclosed herein has a positive electrode layer, a coated porous film layer, and a negative electrode layer in this order. In the zinc secondary battery, the positive electrode layer, the coated porous film layer and the negative electrode layer are impregnated with a liquid electrolyte. The coated porous film layer has a porous film layer and a porous coating film formed on the porous film layer. The coated porous film layer is directly adjacent to the negative electrode layer; the porous coating film contains at least one kind selected from a group consisting of Mg(OH)2, Mg2 P2O7, MgTiO3, MgCO3, Ca(OH)2, CaSO4, Ca2 P2O7, SrTiO3, SrF2, TiO2, SnO2, Zr(OH)4, and ZrO2.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a zinc secondary battery.

Background Art

[0002] Patent Document 1 discloses an alkaline zinc storage battery including a separator having at least a first film facing a positive electrode and a second film facing a negative electrode, wherein the first film is an alkali-resistant microporous film, the second film is a polyvinyl alcohol film, and the first film has a metal arbitrarily selected from nickel, iron, cobalt, platinum, palladium, indium, chromium, manganese, titanium, and alloys mainly composed of these.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] There is a demand for suppressing a decrease in charge-discharge capacity when a zinc secondary battery is repeatedly charged and discharged, that is, improving the cycle characteristics of the zinc secondary battery.

[0005] An object of the present disclosure is to provide a zinc secondary battery with improved cycle characteristics.

Means for Solving the Problems

[0006] The present inventors have found that the above problems can be achieved by the following means: 《Aspect 1》 A zinc secondary battery having a positive electrode layer, a porous film layer with a coating film, and a negative electrode layer in this order, and the positive electrode layer, the porous film layer with a coating film, and the negative electrode layer being impregnated with an electrolytic solution. The porous film layer with the coating film has a porous film layer and a porous coating film formed on the porous film layer. The porous film layer with the coating film is directly adjacent to the negative electrode layer, and the porous coating film contains at least one selected from the group consisting of Mg(OH) 2 , Mg 2 P 2 O 7 , MgTiO 3 , MgCO 3 , Ca(OH) 2 , CaSO 4 , Ca 2 P 2 O 7 , SrTiO 3 , SrF 2 , TiO 2 , SnO 2 , Zr(OH) 4 , and ZrO 2 . Zinc secondary battery. <<Aspect 2>> The zinc secondary battery according to Aspect 1, further having a non-woven fabric layer on the positive electrode layer side than the porous film layer with the coating film. <<Aspect 3>> The zinc secondary battery according to Aspect 2, further having a porous film layer on the positive electrode layer side than the non-woven fabric layer. <<Aspect 4>> The zinc secondary battery according to any one of Aspects 1 to 3, wherein the porous film layer is a porous resin film layer. <<Aspect 5>> The zinc secondary battery according to Aspect 4, wherein the porous resin film layer is a polyolefin-based porous layer, a polyamide-based porous layer, or a nylon-based porous layer. <<Aspect 6>> The zinc secondary battery according to any one of Aspects 1 to 5, wherein the electrolytic solution is an alkaline electrolytic solution. <<Aspect 7>> The zinc secondary battery according to any one of Aspects 1 to 6, wherein the electrolytic solution contains Zn(OH) 4 2- .

Advantages of the Invention

[0007] According to the present disclosure, a zinc secondary battery with improved cycle characteristics can be provided.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Modes for Carrying Out the Invention

[0009] Hereinafter, embodiments of the present disclosure will be described in detail. It should be noted that the present disclosure is not limited to the following embodiments and can be variously modified and implemented within the scope of the gist of the disclosure.

[0010] The zinc secondary battery of the present disclosure has a positive electrode layer, a porous film layer with a coating film, and a negative electrode layer in this order, and the positive electrode layer, the porous film layer with a coating film, and the negative electrode layer are impregnated with an electrolytic solution. The zinc secondary battery, wherein the porous film layer with a coating film has a porous film layer and a porous coating film formed on the porous film layer, the porous film layer with a coating film is directly adjacent to the negative electrode layer, and the porous coating film is Mg(OH) 2 , Mg 2 P 2 O 7 , MgTiO 3 , MgCO 3 , Ca(OH) 2 , CaSO 4 , Ca 2 P 2 O 7 , SrTiO 3 , SrF 2 , TiO 2 , SnO 2 , Zr(OH) 4 , and ZrO 2 and contains at least one selected from the group consisting of. The zinc secondary battery is

[0011] The zinc secondary battery of the present disclosure may be, for example, a nickel-zinc secondary battery, a silver oxide-zinc secondary battery, a manganese oxide-zinc secondary battery, a zinc-air secondary battery, and various other alkaline zinc secondary batteries. In such a zinc secondary battery, a discharge reaction as shown in the following reaction formula (1) occurs at the negative electrode, and the zincate anion (Zn(OH) 4 2- ) generated in this way moves in the electrolytic solution and may precipitate as zinc oxide (ZnO) at an unintended location as shown in the following reaction formula (2). Discharge reaction: Zn + 4OH - → Zn(OH) 4 2- + 2e - … Reaction formula (1) Precipitation reaction: Zn(OH) 4 2- → ZnO + H 2 O + 2OH - … Reaction formula (2)

[0012] Generally, a zinc secondary battery may have a reduced charge-discharge capacity by repeating charge and discharge. One cause of the reduction in the charge-discharge capacity can be the segregation of zinc oxide (ZnO) at the negative electrode. Therefore, it is conceivable to suppress the reduction in the charge-discharge capacity of the zinc secondary battery by suppressing such segregation.

[0013] The segregation of zinc oxide in the negative electrode layer is caused by the concentration unevenness of Zn(OH) 4 2- in the electrolytic solution due to repeated charge and discharge.

[0014] In the zinc secondary battery of the present disclosure, a specific type of metal compound, namely Mg(OH) 2 , Mg 2 P 2 O 7 , MgTiO 3 , MgCO 3 , Ca(OH) 2 , CaSO 4 , Ca 2 P 2 O 7 , SrTiO 3 , SrF 2 , TiO 2 , SnO 2 , Zr(OH) 4 , and ZrO 2 A coated porous film layer having a porous coating film containing at least one selected from the group consisting of is directly adjacent to the negative electrode layer.

[0015] When the porous coating film containing the above metal compound is disposed in the vicinity of the negative electrode layer, the diffusion of Zn(OH) 4 2- in the electrolytic solution, particularly the diffusion from the vicinity of the negative electrode layer to the positive electrode layer side, is suppressed. Also, preferably, Zn(OH) 4 2- remains in the vicinity of the negative electrode layer.

[0016] Therefore, in the zinc secondary battery of the present disclosure, segregation of zinc oxide in the negative electrode layer is suppressed, thereby suppressing a decrease in charge-discharge capacity when the zinc secondary battery is repeatedly charged and discharged. That is, in the zinc secondary battery of the present disclosure, the cycle characteristics of the zinc secondary battery are improved.

[0017] In general, in a zinc secondary battery using an electrolytic solution, a nonwoven fabric layer may be disposed between the negative electrode layer and the positive electrode layer from the viewpoint of holding the electrolytic solution. Although it was considered to directly form a porous coating film on the nonwoven fabric layer, such a configuration did not result in an improvement in the cycle characteristics of the zinc secondary battery.

[0018] FIG. 1 is a schematic diagram showing a zinc secondary battery 100 according to the first embodiment of the present disclosure.

[0019] As shown in FIG. 1, the zinc secondary battery 100 according to the first embodiment of the present disclosure includes a positive electrode layer 10, a porous film layer 20 with a coating film, and a negative electrode layer 30 in this order, and the positive electrode layer 10, the porous film layer 20 with a coating film, and the negative electrode layer 30 are impregnated with an electrolytic solution. The positive electrode layer 10 has a structure in which a positive electrode current collector layer 11 and a positive electrode active material layer 12 are laminated on each other. Similarly, the negative electrode layer 30 also has a structure in which a negative electrode current collector layer 32 and a negative electrode active material layer 31 are laminated on each other.

[0020] In the zinc secondary battery 100 of the present disclosure, the porous film layer 20 with a coating film has a porous film layer 21 and a porous coating film 22 formed on the porous film layer 21. The porous film layer 20 with a coating film is directly adjacent to the negative electrode layer 30. In particular, in FIG. 1, the porous coating film 22 is directly adjacent to the negative electrode layer 30.

[0021] The porous coating film 22 is Mg(OH) 2 , Mg 2 P 2 O 7 , MgTiO 3 , MgCO 3 , Ca(OH) 2 , CaSO 4 , Ca 2P 2 O 7 、 SrTiO 3 、 SrF 2 、 TiO 2 、 SnO 2 、 Zr(OH) 4 、 and at least one selected from the group consisting of ZrO 2 is contained.

[0022] In the zinc secondary battery 100 according to the first embodiment of the present disclosure, due to the porous coating film 22 containing the above metal compound being disposed in the vicinity of the negative electrode layer 30, particularly the negative electrode active material layer 31, the diffusion of Zn(OH) 4 2- dissolved in the electrolyte, particularly the diffusion to the positive electrode layer 10 side beyond the porous coating film 22, is suppressed. Also, preferably, Zn(OH) 4 2- remains in the vicinity of the negative electrode layer 30, particularly in the vicinity of the negative electrode active material layer 31. Thereby, the segregation of zinc oxide in the negative electrode layer 30, specifically the negative electrode active material layer 31, is suppressed, and as a result, the cycle characteristics of the zinc secondary battery 100 are improved.

[0023] FIG. 2 is a schematic diagram showing a zinc secondary battery 101 according to the second embodiment of the present disclosure.

[0024] As shown in FIG. 2, in the zinc secondary battery 101 according to the second embodiment of the present disclosure, compared with the configuration shown in FIG. 1, the stacking order of the porous film layer 21 and the porous coating film 22 in the coated porous film layer 20 is different. That is, in the zinc secondary battery 101 shown in FIG. 2, the porous coating film 22 is adjacent to the negative electrode layer 30, specifically the negative electrode active material layer 31, via the porous film layer 21. In the configuration shown in FIG. 2, although the porous coating film 22 is separated from the negative electrode layer 30 compared with the configuration shown in FIG. 1, since the distance between the porous coating film 22 and the negative electrode layer 30 is sufficiently close, the diffusion of Zn(OH) 4 2- in the electrolyte is suppressed, and as a result, the cycle characteristics of the zinc secondary battery 101 are improved.

[0025] FIG. 3 is a schematic diagram showing a zinc secondary battery 102 according to a third embodiment of the present disclosure.

[0026] As shown in FIG. 3, in the zinc secondary battery 102 according to the third embodiment of the present disclosure, in addition to the configuration shown in FIG. 1, a nonwoven fabric layer 40 is disposed between the porous film layer 20 with a coating film and the positive electrode layer 10. Even in such a configuration, for the same reason as the configuration shown in FIG. 1, improvement in the cycle characteristics of the zinc secondary battery 102 can be obtained.

[0027] FIG. 4 is a schematic diagram showing a zinc secondary battery 103 according to a fourth embodiment of the present disclosure.

[0028] As shown in FIG. 4, in the zinc secondary battery 103 according to the fourth embodiment of the present disclosure, in addition to the configuration shown in FIG. 3, a porous film layer 50 is further provided between the nonwoven fabric layer 40 and the positive electrode layer 10. Even in such a configuration, for the same reason as the configuration shown in FIG. 1, improvement in the cycle characteristics of the zinc secondary battery 102 can be obtained.

[0029] Note that FIGS. 1 to 4 are not intended to limit the zinc secondary battery of the present disclosure.

[0030] Unlike the zinc secondary battery of the present disclosure, in zinc secondary batteries 200 and 201 different from the embodiments of the present disclosure shown in FIGS. 5 and 6 below, for example, improvement in the cycle characteristics of the zinc secondary battery cannot be obtained.

[0031] FIG. 5 is a schematic diagram showing a zinc secondary battery 200 different from the embodiments of the present disclosure.

[0032] As shown in FIG. 5, in the zinc secondary battery 200 different from the embodiments of the present disclosure, compared with the configuration shown in FIG. 1, the nonwoven fabric layer 40 is disposed between the porous film layer 20 with a coating film and the negative electrode layer 30. In such a configuration, the nonwoven fabric layer 40 is disposed between the porous coating film 22 and the negative electrode layer 30, and the porous coating film 22 is largely separated from the negative electrode layer 30. Therefore, Zn(OH) dissolved in the electrolytic solution 4 2-Diffusion in the electrolyte solution, particularly diffusion from the vicinity of the negative electrode layer to the positive electrode layer side, is not suppressed. Therefore, improvement in the cycle characteristics of the zinc secondary battery cannot be obtained.

[0033] Further, FIG. 6 is a schematic diagram showing yet another zinc secondary battery 201 different from the embodiments of the present disclosure.

[0034] As shown in FIG. 6, in the zinc secondary battery 201 that is further different from the embodiments of the present disclosure, similar to the configuration shown in FIG. 1, the porous film layer 20 with a coating film itself is directly adjacent to the negative electrode layer. However, in the configuration shown in FIG. 6, instead of the porous film layer 20 with a coating film, a porous coating film 22 is directly formed on the nonwoven fabric layer 40. In such a configuration, since the porous coating film cannot be formed sufficiently densely, Zn(OH) dissolved in the electrolyte solution 4 2- diffusion in the electrolyte solution, particularly diffusion from the vicinity of the negative electrode layer to the positive electrode layer side, cannot be sufficiently suppressed, and improvement in the cycle characteristics of the zinc secondary battery cannot be obtained.

[0035] 《Positive Electrode Layer》 The positive electrode layer may have a structure in which a positive electrode active material layer is laminated on a positive electrode current collector, for example, a structure in which the surface of the positive electrode current collector is covered by the positive electrode active material layer.

[0036] (Positive Electrode Current Collector) The positive electrode current collector may be a material having conductivity, such as a metal such as stainless steel, nickel, or titanium, or carbon, etc., but is not limited thereto. The material of the positive electrode current collector may be nickel.

[0037] The shape of the current collector is not particularly limited, and examples thereof include a rod shape, a foil shape, a plate shape, a mesh shape, or a porous body. The current collector may be a metal cermet.

[0038] (Positive Electrode Active Material Layer) The positive electrode active material layer contains a positive electrode active material, and optionally a binder and other additives. The positive electrode active material can be appropriately selected according to the type of the zinc secondary battery. The positive electrode active material may include, for example, at least one selected from the group consisting of nickel hydroxide, nickel oxyhydroxide, manganese hydroxide, manganese oxyhydroxide, manganese dioxide, silver, silver oxide, and oxygen gas.

[0039] Examples of the binder include, but are not limited to, styrene-butadiene rubber (SBR).

[0040] 《Separator Layer》 The zinc secondary battery of the present disclosure has a separator layer between the positive electrode layer and the negative electrode layer. Here, the coated porous film layer in the zinc secondary battery of the present disclosure is the whole or a part of the separator layer.

[0041] In addition to the coated porous film layer, the separator layer may further have a plurality of layers, for example, a porous film layer different from the porous film layer constituting the nonwoven fabric layer and the coated porous film layer.

[0042] When the separator layer has other layers other than the coated porous film layer, these layers are disposed between the coated porous film layer and the positive electrode layer.

[0043] 〈Coated Porous Film Layer〉 The coated porous film layer has a porous film layer and a porous coating film formed on the porous film layer.

[0044] The coated porous film layer is directly adjacent to the negative electrode layer. The coated porous film layer is disposed such that either the porous film layer or the porous coating film faces the negative electrode layer. Here, Zn(OH) in the electrolyte 4 2-From the perspective of further suppressing the diffusion, it is particularly preferable that the porous film layer with a coating film is arranged such that the porous coating film faces the negative electrode layer. Note that "directly adjacent" means adjacent in a state where no other layer is included in between.

[0045] (Porous film layer) The porous film layer is a porous layer that is insulating and has through-holes penetrating both sides of the film. The porous film layer may be hydrophobic or hydrophilic.

[0046] The porosity and average pore diameter of the porous film layer may be the porosity and pore diameter generally required for a separator for a zinc secondary battery.

[0047] The thickness of the porous film layer may be, for example, 10 μm to 1000 μm. The thickness of the porous film layer may be 10 μm or more, 50 μm or more, or 100 μm or more, and may be 1000 μm or less, 500 μm or less, or 200 μm or less.

[0048] For the porous film layer, for example, a resin porous film layer can be used, more specifically, a polyolefin-based porous layer, a polyamide-based porous layer, or a nylon-based porous layer, but it is not limited thereto.

[0049] Here, the porous film layer may be hydrophilized, for example, by imparting hydrophilic functional groups.

[0050] Note that the fact that the porous film layer is "porous" means that it has a plurality of through-holes penetrating the front and back of the layer. Therefore, the porous film layer may be, for example, a sponge-like layer.

[0051] (Porous coating film) The porous coating film is Mg(OH) 2 , Mg 2 P 2 O 7 , MgTiO 3 , MgCO 3, Ca(OH) 2 , CaSO 4 , Ca 2 P 2 O 7 , SrTiO 3 , SrF 2 , TiO 2 , SnO 2 , Zr(OH) 4 , and ZrO 2 contains at least one selected from the group consisting of.

[0052] The porous coating film can be formed, for example, by dispersing the above metal compound and binder in a dispersion medium to prepare an ink, and applying and drying it on the porous film layer.

[0053] 〈Nonwoven fabric layer〉 The zinc secondary battery of the present disclosure can further have a nonwoven fabric layer on the positive electrode layer side rather than the porous film layer with a coating film. In other words, in the zinc secondary battery of the present disclosure, the separator layer can have a structure in which a porous film layer with a coating film and a nonwoven fabric layer are laminated in order from the negative electrode layer side.

[0054] The nonwoven fabric layer may be, for example, a cellulose-based nonwoven fabric.

[0055] 〈Porous film layer〉 The zinc secondary battery of the present disclosure can further have a porous film layer on the positive electrode layer side rather than the porous film layer with a coating film. In other words, in the zinc secondary battery of the present disclosure, the separator layer can have a structure in which, for example, a porous film layer with a coating film, a nonwoven fabric layer, and a porous film layer are laminated in order from the negative electrode layer side.

[0056] 《Negative electrode layer》 The negative electrode layer may have a structure in which a negative electrode active material layer is laminated on a negative electrode current collector, for example, a structure in which the surface of the negative electrode current collector is covered with the negative electrode active material layer.

[0057] (Negative electrode current collector) The negative electrode current collector may be a material having conductivity, such as a metal such as stainless steel, aluminum, copper, nickel, iron, tin, or titanium, or carbon, etc., but is not limited thereto. The material of the negative electrode current collector may be tin.

[0058] The shape of the current collector is not particularly limited, and examples thereof include a rod shape, a foil shape, a plate shape, a mesh shape, or a porous body. The current collector may be a metal cermet.

[0059] (Negative electrode active material layer) The negative electrode active material layer contains zinc and zinc oxide, and optionally a binder and other additives. The zinc-based negative electrode active material layer may further contain a zinc compound such as calcium zincate.

[0060] Examples of the binder include, but are not limited to, styrene-butadiene rubber (SBR) or polytetrafluoroethylene (PTFE).

[0061] 《Electrolyte》 In the zinc secondary battery of the present disclosure, the positive electrode layer, the porous film layer with a coating film, and the negative electrode layer are impregnated with an electrolyte.

[0062] The electrolyte can be an aqueous solution, more specifically an alkaline electrolyte. The alkaline electrolyte is an electrolyte containing an alkali metal hydroxide, and more specifically, examples thereof include potassium hydroxide, sodium hydroxide, lithium hydroxide, or ammonium hydroxide. Potassium hydroxide is preferable as the electrolyte. The electrolyte may further contain other inorganic and organic additives.

[0063] The electrolyte can further dissolve zinc oxide. Zinc oxide may be dissolved in the electrolyte in a saturated state at room temperature. In other words, the electrolyte can contain Zn(OH) 4 2- Thereby.

Examples

[0064] 《Examples 1 to 13, and Comparative Examples 1 and 2》 The zinc secondary battery of Example 1 was prepared as follows.

[0065] 〈Preparation of electrolyte〉 A 6 mol / L potassium hydroxide aqueous solution was prepared using 4 mol / L and 8 mol / L potassium hydroxide aqueous solutions. ZnO was added to the 6 mol / L potassium hydroxide aqueous solution until precipitates remained, and the temperature was adjusted in a constant temperature bath at 25°C for 3 hours or more to obtain an electrolyte.

[0066] 〈Preparation of separator layer〉 A nonwoven separator was sandwiched between hydrophilized polypropylene separators to obtain a separator. The polypropylene separator had a thickness of 20 μm.

[0067] Next, a porous coating film was formed on the polypropylene separator.

[0068] Specifically, the metal compound powder, styrene-butadiene rubber (SBR), and carboxymethyl cellulose (CMC) used in each example shown in Table 1 below were weighed so that the mass ratio was 97.0:2.5:0.5, kneaded in a mortar, and then the hardness was adjusted with water and mixed at 2000 rpm for 1 minute with a bubble kneader to prepare an ink for forming a porous coating film. The ink for forming a porous coating film was applied to the surface of the polypropylene separator with a doctor blade, and after natural drying, it was dried overnight in a reduced pressure environment at 80°C to form a porous coating film. In Comparative Example 1, no porous coating film was formed on the polypropylene separator.

[0069]

Table 1

[0070] The hydrophilization treatment of the polypropylene separator was prepared by adding 1 g of surfactant to a solution of 50 g of ethanol and 50 g of ultrapure water, fully diffusing the solution, cutting the polypropylene separator into 7 cm, immersing it in the solution for 1 minute, pulling up the immersed separator and allowing it to air-dry, and then allowing it to stand in a constant temperature bath at 40 °C for 3 hours or more.

[0071] <Preparation of the positive electrode layer> Ni(OH) 2 (including auxiliaries), SBR, and CMC were weighed in a mass ratio of 97.0:2.5:0.5, kneaded in a mortar, and then the solidity was adjusted with water and mixed at 2000 rpm for 1 minute with a bubble kneader to prepare the positive electrode composite ink. The positive electrode composite ink was coated on the surface of the Ni foil with a doctor blade, air-dried, and then dried overnight in a reduced-pressure environment at 80 °C to prepare the positive electrode layer.

[0072] <Preparation of the negative electrode layer> ZnO, Zn, SBR, and CMC were weighed in a mass ratio of 77.0:20.0:2.5:0.5, kneaded in a mortar, and then the solidity was adjusted with water and mixed at 2000 rpm for 1 minute with a bubble kneader to prepare the negative electrode composite ink. The negative electrode composite ink was coated on the surface of the Cu foil plated with Sn with a doctor blade, air-dried, and then dried overnight in a reduced-pressure environment at 80 °C to prepare the negative electrode layer.

[0073] <Assembly of the battery> The positive electrode layer, separator layer, and negative electrode layer were laminated in this order and housed in a battery case. Then, the battery case was filled with an electrolyte solution to form a zinc secondary battery.

[0074] Note that the separator layer was arranged in the order from the negative electrode layer side as a porous coating film, a polypropylene separator, a non-woven separator, and a polypropylene separator.

[0075] <Charge and discharge cycle test> For each zinc secondary battery, a charge-discharge cycle test was performed, and the number of cycles at which the discharge capacity fell below 70% of the initial value was determined.

[0076] The charge-discharge cycle test was carried out in the charge-discharge range of 0% to 50% of the state of charge (SOC) when the theoretical charge capacity of the positive electrode layer was taken as 100%. The C-rate was 3.5 mA / cm 2 It was. The cut-off voltage was 2 V during charging and 1.3 V during discharging. The cycle test was performed with a 5-minute interval for each cycle.

[0077] For each zinc secondary battery, the number of cycles at which the discharge capacity fell below 70% of the initial value was defined as the cycle life, and the value obtained by dividing it by the negative / positive capacity ratio (cycle life / capacity ratio) was determined.

[0078] 〈Results〉 The results are shown in Fig. 7.

[0079] As shown in Fig. 7, in the zinc secondary batteries of Examples 1 to 13 using Mg(OH) 2 , Mg 2 P 2 O 7 , MgTiO 3 , MgCO 3 , Ca(OH) 2 , CaSO 4 ·2H 2 O, Ca 2 P 2 O 7 , SrTiO 3 , SrF 2 , TiO 2 , SnO 2 , Zr(OH) 4 and ZrO 2 as the porous coating film materials, it is shown that the cycle life / capacity ratio is larger and the cycle characteristics are improved compared with Comparative Example 1 in which no porous coating film was formed.

[0080] On the other hand, as the material of the porous coating film, MgF 2In Comparative Example 2 using this, the cycle life / capacity ratio was smaller than that in Comparative Example 1 where the porous coating film was not formed, and the cycle characteristics rather deteriorated.

[0081] 《Example 1, and Comparative Examples 1, 3, and 4》 〈Preparation of Zinc Secondary Battery〉 Example 1 and Comparative Example 1 are the same as those prepared in the above 《Examples 1 to 13, and Comparative Examples 1 and 2》.

[0082] The zinc secondary battery of Comparative Example 3 was produced in the same manner as Example 1, except that the separator layer was arranged such that it was, in order from the negative electrode layer side, a polypropylene separator, a nonwoven fabric separator, a polypropylene separator, and a porous coating film.

[0083] The zinc secondary battery of Comparative Example 4 was produced in the same manner as Example 1, except that as the separator layer, a porous coating film was formed by directly coating the nonwoven fabric separator with the ink for forming the porous coating film. Note that the separator layer of the zinc secondary battery of Comparative Example 4 was arranged such that it was, in order from the negative electrode layer side, a porous coating film and a nonwoven fabric separator.

[0084] That is, the configuration of the separator layer of the zinc secondary battery of each example is as follows. Example 1: (Negative electrode side) Porous coating film / Polypropylene separator / Nonwoven fabric separator / Polypropylene separator (Positive electrode side) Comparative Example 1: (Negative electrode side) Polypropylene separator / Nonwoven fabric separator / Polypropylene separator (Positive electrode side) Comparative Example 3: (Negative electrode side) Polypropylene separator / Nonwoven fabric separator / Polypropylene separator / Porous coating film (Positive electrode side) Comparative Example 4: (Negative electrode side) Porous coating film / Nonwoven fabric separator (Positive electrode side)

[0085] 〈Test〉 By the method described in the <Charge and Discharge Cycle Test> of the above <Examples 1 to 13, and Comparative Examples 1 and 2>, a charge and discharge cycle test was carried out on the zinc secondary battery of each example.

[0086] <Results> The results are shown in Figure 8.

[0087] As shown in Figure 8, for the zinc secondary battery of Example 1 in which the configuration of the separator layer of the zinc secondary battery was (negative electrode side) polypropylene separator / non-woven fabric separator / polypropylene separator (positive electrode side), the configuration of the separator layer of the zinc secondary battery was (negative electrode side) polypropylene separator / non-woven fabric separator / polypropylene separator (positive electrode side) for Comparative Example 1, (negative electrode side) polypropylene separator / non-woven fabric separator / polypropylene separator / porous coating film (positive electrode side) for Comparative Example 3, and (negative electrode side) porous coating film / non-woven fabric separator (positive electrode side) for Comparative Example 4, all had a small cycle life / capacity ratio.

Explanation of Reference Numerals

[0088] 100 to 103, as well as 200 and 201 zinc secondary batteries 10 Positive electrode layer 11 Positive electrode current collector layer 12 Positive electrode active material layer 20 Porous film layer with coating film 21 Porous film layer 22 Porous coating film 30 Negative electrode layer 31 Negative electrode active material layer 32 Negative electrode current collector layer 40 Non-woven fabric layer 50 Porous film layer

Claims

1. A zinc secondary battery having a positive electrode layer, a porous film layer with a coating film, and a negative electrode layer in this order, and the positive electrode layer, the porous film layer with a coating film, and the negative electrode layer being impregnated with an electrolytic solution, wherein the porous film layer with a coating film has a porous film layer and a porous coating film formed on the porous film layer, the porous coating film is directly adjacent to the negative electrode layer, and The porous coating film contains at least one selected from the group consisting of Mg ２ P ２ O ７ , MgTiO ３ , CaSO ４ , Ca ２ P ２ O ７ , SrTiO ３ , SrF ２ , TiO ２ , SnO ２ , Zr(OH) ４ , and ZrO ２ . a zinc secondary battery.

2. The zinc secondary battery according to claim 1, further having a non-woven fabric layer on the positive electrode layer side of the porous film layer with a coating film.

3. The zinc secondary battery according to claim 2, further having a porous film layer on the positive electrode layer side of the non-woven fabric layer.

4. The zinc secondary battery according to claim 1 or 2, wherein the porous film layer is a porous resin film layer.

5. The zinc secondary battery according to claim 4, wherein the porous resin film layer is a polyolefin-based porous layer, a polyamide-based porous layer, or a nylon-based porous layer.

6. The zinc secondary battery according to claim 1 or 2, wherein the electrolytic solution is an alkaline electrolytic solution.

7. The electrolytic solution contains Zn(OH) ４ ２－ The zinc secondary battery according to claim 1 or 2

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