Nickel-hydrogen battery and method of making

Abstract

The application discloses a nickel-hydrogen battery and a preparation method thereof. The nickel-hydrogen battery comprises a positive electrode and a negative electrode; the positive electrode comprises a positive electrode base body and a positive electrode material loaded on the positive electrode base body, and the negative electrode comprises a negative electrode base body and a negative electrode material loaded on the negative electrode base body; the positive electrode material comprises a nickel-containing substance, a metal oxide, a cobalt oxyhydroxide and a positive electrode binder; the nickel-containing substance comprises cobalt-coated spherical nickel hydroxide and nickel hydroxide, and the metal oxide is selected from one or more of zinc oxide, titanium oxide and yttrium oxide; and the negative electrode material comprises a La-Y-Ni hydrogen storage alloy, a conductive agent, a negative electrode binder and yttrium oxide. The nickel-hydrogen battery has a high charge retention rate.

Description

Technical Field

[0001] This invention relates to a nickel-metal hydride battery and its preparation method. Background Technology

[0002] Nickel-metal hydride (Ni-MH) batteries are a new type of green battery that has attracted widespread attention due to their high energy, long lifespan, and pollution-free characteristics.

[0003] CN115189041A discloses a low-temperature nickel-metal hydride battery, comprising a positive electrode, a negative electrode, and an electrolyte. The positive electrode comprises a nickel foam matrix, cobalt-coated spherical nickel hydroxide as the active material, graphene as the conductive agent, sodium carboxymethyl cellulose as the binder, and ytterbium oxide and lanthanum oxide as additives. The negative electrode comprises a copper mesh matrix, a hydrogen storage alloy as the active material, graphene as the conductive agent, polytetrafluoroethylene emulsion as the binder, and copper oxide as the additive. The electrolyte comprises sodium hydroxide, potassium hydroxide, barium hydroxide, and carboxymethyl cellulose. This nickel-metal hydride battery exhibits a low charge retention rate.

[0004] CN101299469A discloses a nickel-metal hydride low self-discharge battery, including a positive electrode, a negative electrode, an electrolyte, and a battery separator. The positive electrode is formed by filling a foamed nickel substrate with nickel hydroxide active material to form a nickel hydroxide electrode, and a layer of Co is micro-coated on the surface of ordinary spherical nickel hydroxide particles by chemical plating or oxidation. 3+ Co 3+ The content of [agent] is 3-5% of the total particle weight, forming nickel hydroxide particles with special properties. Simultaneously, at least one of the following additives, selected from oxides, fluorides, sulfides, or sulfates of calcium, manganese, arsenic, yttrium, ytterbium, and tungsten, is added to the nickel hydroxide electrode via mechanical mixing, with the additive content ranging from 0.1% to 10% of the total nickel hydroxide weight. The negative electrode uses Mg-based superlattice alloy powder, with one or more of C modifiers and conductive agents added. A special binder is composed of one or more of hydroxypropyl methylcellulose, polytetrafluoroethylene emulsion, and carboxylated styrene-butadiene latex. The negative electrode of this nickel-metal hydride battery uses Mg-based superlattice alloy powder, which is prone to combustion and explosion during the manufacturing process, posing a safety hazard. Summary of the Invention

[0005] In view of this, one object of the present invention is to provide a nickel-metal hydride battery. This nickel-metal hydride battery has a high charge retention rate. Furthermore, this nickel-metal hydride battery has a high discharge capacity.

[0006] Another object of the present invention is to provide a method for preparing a nickel-metal hydride battery. This method can improve the charge retention rate of the nickel-metal hydride battery.

[0007] The above-mentioned technical objectives are achieved through the following technical solutions.

[0008] On one hand, the present invention provides a nickel-metal hydride battery, including a positive electrode and a negative electrode; the positive electrode includes a positive electrode substrate and a positive electrode material loaded on the positive electrode substrate, and the negative electrode includes a negative electrode substrate and a negative electrode material loaded on the negative electrode substrate;

[0009] The cathode material includes a nickel-containing substance, a metal oxide, cobalt hydroxyl oxide, and a cathode binder; the nickel-containing substance includes cobalt-coated spherical nickel hydroxide and nickel hydroxide, and the metal oxide is selected from one or more of zinc oxide, titanium oxide, and yttrium oxide;

[0010] The negative electrode material includes a La-Y-Ni hydrogen storage alloy, a conductive agent, a negative electrode binder, and yttrium oxide.

[0011] According to the nickel-metal hydride battery of the present invention, preferably, the La-Y-Ni hydrogen storage alloy has the following composition:

[0012] RE x Y y Ni d Mn a Al b M c

[0013] RE is selected from one or more of La, Ce, Pr, and Nd, and must contain La; M is selected from one or more of Co, Cu, Fe, and B.

[0014] Where 0.5≤x≤0.8, x+y=2, 0.2≤a≤0.6, 0.2≤b≤0.4, 0.1≤c≤0.3, 7.2≤a+b+c+d≤7.7; x, y, a, b, c, and d represent the molar fractions of each element.

[0015] According to the nickel-metal hydride battery of the present invention, preferably, the positive electrode substrate is nickel foam, the negative electrode substrate is nickel-plated steel strip, the positive electrode binder is selected from one or more of sodium carboxymethyl cellulose, polytetrafluoroethylene or styrene-butadiene rubber, the negative electrode binder is selected from one or more of polytetrafluoroethylene, styrene-butadiene rubber or sodium carboxymethyl cellulose, and the conductive agent is selected from one or more of carbon black, acetylene black or graphene.

[0016] According to the nickel-metal hydride battery of the present invention, preferably, the amount of nickel-containing material is 90-97 parts by weight, the amount of metal oxide is 1.5-4 parts by weight, the amount of cobalt hydroxyl oxide is 3-5 parts by weight, and the amount of positive electrode binder is 2-7 parts by weight; based on the nickel-containing material, the content of cobalt-coated spherical nickel hydroxide is 65-85 wt%, and the content of nickel hydroxide is 15-30 wt%.

[0017] The amount of La-Y-Ni hydrogen storage alloy is 85-94 parts by weight, the amount of conductive agent is 0.2-0.9 parts by weight, the amount of negative electrode binder is 8-14 parts by weight, and the amount of yttrium oxide is 0.2-1.0 parts by weight.

[0018] The La-Y-Ni hydrogen storage alloy is used in powder form, with at least a portion of the conductive agent coated on the surface of the La-Y-Ni hydrogen storage alloy powder.

[0019] According to the nickel-metal hydride battery of the present invention, preferably, a positive electrode adhesive layer containing a first electrolyte is formed on the surface of the positive electrode to obtain an adhesive-impregnated positive electrode; wherein, the positive electrode adhesive layer is mainly formed of polytetrafluoroethylene or styrene-butadiene rubber, and the first electrolyte is composed of potassium hydroxide, sodium hydroxide and lithium hydroxide in a weight ratio of 6-12:19-25:3.5-7.5.

[0020] According to the nickel-metal hydride battery of the present invention, preferably, a negative electrode adhesive layer containing a second electrolyte is formed on the surface of the negative electrode to obtain an adhesive-impregnated negative electrode; wherein, the negative electrode adhesive layer is mainly formed of polytetrafluoroethylene or styrene-butadiene rubber, and the second electrolyte is composed of potassium hydroxide, sodium hydroxide and lithium hydroxide in a weight ratio of 6-12:19-25:3.5-7.5.

[0021] According to the present invention, the nickel-metal hydride battery preferably further includes an electrolyte containing a third electrolyte, the third electrolyte being composed of potassium hydroxide, sodium hydroxide and lithium hydroxide in a weight ratio of 6-12:19-25:3.5-7.5.

[0022] According to the nickel-metal hydride battery of the present invention, preferably, the nickel-metal hydride battery further includes a separator and a casing;

[0023] The membrane is located between the impregnated negative electrode and the impregnated positive electrode, and the membrane is selected from one or more of sulfonated membranes, fluorinated membranes, or grafted membranes.

[0024] The impregnated positive electrode, impregnated negative electrode, separator, and electrolyte are located inside the outer casing.

[0025] On the other hand, the present invention provides a method for preparing a nickel-metal hydride battery, comprising the following steps:

[0026] (1) Provide a positive electrode material including a nickel-containing substance, a metal oxide, cobalt hydroxyl oxide and a positive electrode binder, coat the positive electrode material onto a positive electrode substrate to obtain a coated positive electrode substrate; soften and trim the coated positive electrode substrate to obtain a positive electrode; immerse the positive electrode in an electrolyte containing a first electrolyte, then immerse it in latex, and dry it to obtain a latex-impregnated positive electrode;

[0027] The nickel-containing material includes cobalt-coated spherical nickel hydroxide and nickel hydroxide, and the metal oxide is selected from one or more of zinc oxide, titanium oxide and yttrium oxide;

[0028] (2) The negative electrode material slurry is coated onto the negative electrode substrate to obtain the coated negative electrode substrate. The coated negative electrode substrate is softened and trimmed to obtain the negative electrode. The negative electrode is immersed in an electrolyte containing the second electrolyte, then immersed in latex, and dried to obtain the latex-impregnated negative electrode.

[0029] The negative electrode slurry includes negative electrode material and water; the negative electrode material includes La-Y-Ni hydrogen storage alloy, conductive agent, negative electrode binder and yttrium oxide;

[0030] (3) Place the diaphragm between the impregnated positive electrode and the impregnated negative electrode, and then wind it into an electrode assembly; place the electrode assembly in the shell to obtain the first pre-product;

[0031] (4) Add the electrolyte containing the third electrolyte to the first pre-product to obtain the second pre-product;

[0032] (5) Precharge the second pre-product to obtain the third pre-product;

[0033] (6) Weld the cap onto the third preform and press the cap into the outer shell to obtain the fourth preform; heat the fourth preform to 40-75°C and then seal it to obtain a nickel-hydrogen battery.

[0034] According to the preparation method of the present invention, preferably, in step (1), the positive electrode substrate is nickel foam, the negative electrode substrate is nickel-plated steel strip, the positive electrode binder is selected from one or more of sodium carboxymethyl cellulose, polytetrafluoroethylene or styrene-butadiene rubber; the first electrolyte is composed of potassium hydroxide, sodium hydroxide and lithium hydroxide in a weight ratio of 6-12:19-25:3.5-7.5.

[0035] In step (2), the negative electrode binder is selected from one or more of polytetrafluoroethylene, styrene-butadiene rubber or sodium carboxymethyl cellulose, and the conductive agent is selected from one or more of carbon black, acetylene black and graphene; the second electrolyte is composed of potassium hydroxide, sodium hydroxide and lithium hydroxide in a weight ratio of 6-12:19-25:3.5-7.5.

[0036] In step (4), the third electrolyte in the electrolyte containing the third electrolyte is composed of potassium hydroxide, sodium hydroxide and lithium hydroxide in a weight ratio of 6-12:19-25:3.5-7.5.

[0037] The nickel-metal hydride battery of the present invention exhibits a high charge retention rate. Furthermore, the nickel-metal hydride battery also possesses a high discharge capacity. The preparation method of the present invention can further improve the charge retention rate of the nickel-metal hydride battery. Detailed Implementation

[0038] The present invention will be further described below with reference to specific embodiments, but the scope of protection of the present invention is not limited thereto.

[0039] Nickel-metal hydride batteries

[0040] The nickel-metal hydride battery of the present invention includes a positive electrode and a negative electrode. In some embodiments, the nickel-metal hydride battery further includes one or more of a separator, an electrolyte, and a casing.

[0041] positive electrode

[0042] The positive electrode of this invention includes a positive electrode substrate and a positive electrode material. The positive electrode material is loaded onto the positive electrode substrate. The positive electrode of this invention can be a positive electrode that has undergone softening and trimming treatment.

[0043] The positive electrode material includes a nickel-containing substance, a metal oxide, cobalt hydroxyl oxide, and a positive electrode binder. In some embodiments, the positive electrode material consists of a nickel-containing substance, a metal oxide, cobalt hydroxyl oxide, and a positive electrode binder.

[0044] The nickel-containing material includes cobalt-coated spherical nickel hydroxide and nickel hydroxide. Preferably, the nickel-containing material consists of cobalt-coated spherical nickel hydroxide and nickel hydroxide. Based on the nickel-containing material, the content of cobalt-coated spherical nickel hydroxide is 65–85 wt%; preferably 70–80 wt%; more preferably 75–78 wt%. Based on the nickel-containing material, the content of nickel hydroxide is 15–30 wt%; preferably 20–25 wt%; more preferably 22–23 wt%.

[0045] The amount of nickel-containing material used can be 90 to 97 parts by weight. In some embodiments, the amount of nickel-containing material used is 92 to 93 parts by weight. In other embodiments, the amount of nickel-containing material used is 94 to 96 parts by weight.

[0046] The metal oxide is selected from one or more of zinc oxide, titanium oxide, and yttrium oxide. Preferably, the metal oxide is zinc oxide. The zinc oxide can be zinc oxide. The titanium oxide can be titanium oxide. The yttrium oxide can be yttrium oxide.

[0047] The amount of metal oxide used can be 1.5 to 4 parts by weight. In some embodiments, the amount of metal oxide used is 2 to 2.2 parts by weight. In other embodiments, the amount of metal oxide used is 2.5 to 3 parts by weight.

[0048] The amount of cobalt hydroxyoxide used can be 3 to 5 parts by weight. In some embodiments, the amount of cobalt hydroxyoxide used is 3.5 to 3.7 parts by weight. In other embodiments, the amount of cobalt hydroxyoxide used is 3.9 to 4 parts by weight.

[0049] The positive electrode binder can be selected from one or more of sodium carboxymethyl cellulose, polytetrafluoroethylene, or styrene-butadiene rubber. In some embodiments, the positive electrode binder is sodium carboxymethyl cellulose. In other embodiments, the positive electrode binder is polytetrafluoroethylene.

[0050] The amount of positive electrode binder can be 2 to 7 parts by weight; preferably 3 to 5 parts by weight; more preferably 3.5 to 4 parts by weight.

[0051] The cathode material formed by the above-mentioned substances can improve the discharge capacity and charge retention rate of nickel-metal hydride batteries. Controlling the dosage of these substances within the aforementioned range can further improve the discharge capacity and charge retention rate of nickel-metal hydride batteries.

[0052] The positive electrode substrate can be nickel foam.

[0053] The length of the positive electrode can be 80–150 mm; preferably 90–120 mm. The width of the positive electrode can be 30–60 mm; preferably 40–50 mm. The thickness of the positive electrode can be 0.3–0.7 mm; preferably 0.4–0.55 mm.

[0054] In some embodiments, a positive electrode adhesive layer containing a first electrolyte is formed on the surface of the positive electrode to obtain an adhesive-impregnated positive electrode. The applicant has found that this can improve the charge retention rate of the battery, possibly because the positive electrode adhesive layer can prevent cracks from forming on the positive electrode during winding that could puncture the separator and reduce the charge retention rate of the battery.

[0055] The positive electrode adhesive layer is mainly formed of polytetrafluoroethylene or styrene-butadiene rubber; preferably, the positive electrode adhesive layer is mainly formed of polytetrafluoroethylene.

[0056] The first electrolyte is composed of potassium hydroxide, sodium hydroxide, and lithium hydroxide in a weight ratio of 6–12:19–25:3.5–7.5. Preferably, the weight ratio of potassium hydroxide, sodium hydroxide, and lithium hydroxide in the first electrolyte is 7–10:20–24:4–7. More preferably, the weight ratio of potassium hydroxide, sodium hydroxide, and lithium hydroxide in the first electrolyte is 8–9:21–23:5–6.

[0057] negative electrode

[0058] The negative electrode of the present invention comprises a negative electrode substrate and a negative electrode material. The negative electrode material is loaded onto the negative electrode substrate. The negative electrode of the present invention can be a negative electrode that has undergone softening and trimming treatment.

[0059] The negative electrode material includes a La-Y-Ni based hydrogen storage alloy, a conductive agent, a negative electrode binder, and yttrium oxide. In some embodiments, the negative electrode material is composed of a La-Y-Ni based hydrogen storage alloy, a conductive agent, a negative electrode binder, and yttrium oxide.

[0060] La-Y-Ni based hydrogen storage alloys have the following composition:

[0061] RE x Y y Ni d Mn a Al b M c

[0062] RE is selected from one or more of La, Ce, Pr, and Nd, and must contain La. In some embodiments, RE is La. In other embodiments, RE is La and Mm. Mm is selected from one or more of Ce, Pr, or Nd. The molar ratio of La to Mm can be (1-3):1; preferably (1.5-2.5):1; more preferably (2-2.5):1.

[0063] x represents the molar fraction of rare earth element RE. 0.5≤x≤0.8; preferably, 0.6≤x≤0.7.

[0064] y represents the molar fraction of yttrium Y. x + y = 2. 1.2 ≤ y ≤ 1.7; preferably, 1.3 ≤ y ≤ 1.6; more preferably, 1.4 ≤ y ≤ 1.5.

[0065] 'a' represents the molar amount of manganese (Mn). 0.2 ≤ a ≤ 0.6; preferably, 0.3 ≤ a ≤ 0.5; more preferably, 0.4 ≤ a ≤ 0.5.

[0066] b represents the molar fraction of aluminum (Al). 0.2 ≤ b ≤ 0.4; preferably, 0.3 ≤ b ≤ 0.4.

[0067] M is selected from one or more of Co, Cu, Fe, and B. According to one embodiment of the present invention, M is Co. c represents the molar amount of M, 0.1 ≤ c ≤ 0.3; preferably, 0.2 ≤ c ≤ 0.3.

[0068] d represents the molar fraction of nickel (Ni). 7.2≤a+b+c+d≤7.7; preferably, 7.3≤a+b+c+d≤7.6; more preferably, 7.4≤a+b+c+d≤7.5. 6≤d≤7; preferably, 6.2≤d≤6.8; more preferably, 6.4≤d≤6.6.

[0069] According to one embodiment of the present invention, the composition of the La-Y-Ni hydrogen storage alloy is La 0.4 Ce 0.2 Y 1.4 Ni 6.5 Mn 0. 4Al 0.3 Co 0.2 .

[0070] This La-Y-Ni hydrogen storage alloy can be prepared using methods commonly used in the field, such as vacuum induction melting, powder metallurgy, and mechanical alloying; it can also be purchased from the Baotou Rare Earth Research Institute. This can improve the discharge capacity and charge retention rate of nickel-hydrogen batteries.

[0071] La-Y-Ni hydrogen storage alloys can be used in powder form. The amount of La-Y-Ni hydrogen storage alloy used can be 85 to 94 parts by weight; preferably 85 to 90 parts by weight; more preferably 86 to 88 parts by weight.

[0072] The conductive agent may be selected from one or more of carbon black, acetylene black, and graphene. The graphene is conductive graphene. In some embodiments, the conductive agent is acetylene black. In other embodiments, the conductive agent is graphene. In some embodiments, at least a portion of the conductive agent is coated on the surface of the La-Y-Ni based hydrogen storage alloy powder.

[0073] The amount of conductive agent can be 0.2 to 0.9 parts by weight; preferably 0.4 to 0.7 parts by weight; more preferably 0.5 to 0.6 parts by weight.

[0074] The amount of negative electrode binder can be 8 to 14 parts by weight; preferably 9 to 13 parts by weight; more preferably 10 to 12 parts by weight.

[0075] The negative electrode binder may be selected from one or more of polytetrafluoroethylene, sodium carboxymethyl cellulose, or styrene-butadiene rubber. In some embodiments, the negative electrode binder is polytetrafluoroethylene. In other embodiments, the negative electrode binder is styrene-butadiene rubber.

[0076] The amount of yttrium oxide can be 0.2 to 1.0 parts by weight; preferably 0.4 to 0.9 parts by weight; more preferably 0.6 to 0.8 parts by weight.

[0077] The negative electrode material formed by the above-mentioned substances can improve the discharge capacity and charge retention rate of nickel-metal hydride batteries. Controlling the dosage of these substances within the aforementioned range can further improve the discharge capacity and charge retention rate of nickel-metal hydride batteries.

[0078] The negative electrode substrate can be nickel-plated steel strip.

[0079] The length of the negative electrode can be 90–160 mm; preferably 120–150 mm. The width of the negative electrode can be 30–60 mm; preferably 40–50 mm. The thickness of the negative electrode can be 0.1–0.5 mm; preferably 0.2–0.3 mm.

[0080] In some embodiments, a negative electrode adhesive layer containing a second electrolyte is formed on the surface of the negative electrode to obtain an impregnated positive electrode. The applicant has found that this can improve the charge retention rate of the battery, possibly because the positive electrode adhesive layer can prevent cracks from forming on the positive electrode during winding that could puncture the separator and reduce the charge retention rate of the battery.

[0081] The negative electrode adhesive layer is mainly formed of polytetrafluoroethylene or styrene-butadiene rubber; preferably, the negative electrode adhesive layer is mainly formed of polytetrafluoroethylene.

[0082] The second electrolyte is composed of potassium hydroxide, sodium hydroxide, and lithium hydroxide in a weight ratio of 6–12:19–25:3.5–7.5. Preferably, the weight ratio of potassium hydroxide, sodium hydroxide, and lithium hydroxide in the second electrolyte is 7–10:20–24:4–7. More preferably, the weight ratio of potassium hydroxide, sodium hydroxide, and lithium hydroxide in the second electrolyte is 8–9:21–23:5–6.

[0083] Electrolyte containing a third electrolyte, diaphragm and casing

[0084] An electrolyte containing a third electrolyte is filled inside the casing. The electrolyte containing the third electrolyte includes the third electrolyte and water. In some embodiments, the electrolyte containing the third electrolyte consists of the third electrolyte and water.

[0085] The third electrolyte is composed of potassium hydroxide, sodium hydroxide, and lithium hydroxide in a weight ratio of 6–12:19–25:3.5–7.5. Preferably, the weight ratio of potassium hydroxide, sodium hydroxide, and lithium hydroxide in the third electrolyte is 7–10:20–24:4–7. More preferably, the weight ratio of potassium hydroxide, sodium hydroxide, and lithium hydroxide in the third electrolyte is 8–9:21–23:5–6.

[0086] The mass ratio of potassium hydroxide to water can be (6-12):(50-75); preferably (7-10):(55-70); more preferably (8-10):(55-60).

[0087] The amount of electrolyte can be 1 to 5 g; preferably 2 to 4 g; more preferably 2.5 to 3 g.

[0088] A separator is located between the impregnated positive electrode and the impregnated negative electrode. The impregnated positive electrode, the impregnated negative electrode, and the separator are all wound within a housing. The separator can be selected from one or more of sulfonated separators, fluorinated separators, or grafted separators. According to one embodiment of the present invention, the separator is a sulfonated separator.

[0089] The outer casing can be made of steel.

[0090] <Preparation Methods of Nickel-Metal Hydride Batteries>

[0091] The method for preparing the nickel-metal hydride battery of the present invention includes the following steps: (1) a positive electrode preparation step; (2) a negative electrode preparation step; (3) a winding step; (4) a step of adding electrolyte; (5) a pre-charging step; and (6) a sealing step. The above numbers do not represent the order of the steps.

[0092] Positive electrode preparation steps

[0093] We provide cathode materials comprising nickel-containing materials, metal oxides, cobalt hydroxyl oxide, and cathode binders. The composition of the cathode materials and the selection of the cathode substrate are as described above and will not be repeated here.

[0094] A cathode material is obtained by mixing a nickel-containing substance, a metal oxide, cobalt hydroxyl oxide, and a cathode binder. The mixing can be performed in a three-dimensional mixer. Specifically, the nickel-containing substance, metal oxide, and cobalt hydroxyl oxide are mixed for time t1, and then the cathode binder is added and mixing continues for time t2 to obtain the cathode material. t1 can be 7–30 h; preferably 10–20 h. t2 can be 0.5–7 h; preferably 1.5–4 h.

[0095] The positive electrode material is coated onto the positive electrode substrate to obtain the coated positive electrode substrate. The positive electrode material can be brushed onto the substrate using a brush. The thickness is controlled by a scraper. Rolling is then used to bond the positive electrode material to the substrate. The positive electrode substrate can be a coated substrate. Polytetrafluoroethylene (PTFE) can be used for the coating. The positive electrode substrate can be pre-pressed before use.

[0096] After the positive electrode material is combined with the positive electrode substrate, it is cut. This allows for the production of a positive electrode of an appropriate size.

[0097] The coated positive electrode substrate is softened and trimmed to obtain the positive electrode. Trimming and softening can be performed in a trimming and softening machine.

[0098] The length, width, and height of the positive electrode are as described above and will not be repeated here.

[0099] The positive electrode is immersed in an electrolyte containing the first electrolyte, then immersed in latex, and dried to obtain a latex-impregnated positive electrode. This process can improve the battery's charge retention rate.

[0100] The electrolyte containing the first electrolyte comprises the first electrolyte and water. In some embodiments, the electrolyte containing the first electrolyte consists of the first electrolyte and water.

[0101] The first electrolyte is composed of potassium hydroxide, sodium hydroxide, and lithium hydroxide in a weight ratio of 6–12:19–25:3.5–7.5. Preferably, the weight ratio of potassium hydroxide, sodium hydroxide, and lithium hydroxide in the first electrolyte is 7–10:20–24:4–7. More preferably, the weight ratio of potassium hydroxide, sodium hydroxide, and lithium hydroxide in the first electrolyte is 8–9:21–23:5–6.

[0102] The mass ratio of potassium hydroxide to water can be (6-12):(50-75); preferably (7-10):(55-70); more preferably (8-10):(55-60).

[0103] The soaking time in the electrolyte containing the first electrolyte can be 5 to 60 minutes; preferably 10 to 40 minutes; more preferably 20 to 30 minutes.

[0104] The latex can be a polytetrafluoroethylene (PTFE) latex or a styrene-butadiene rubber (SBR) latex; preferably a PTFE latex. The immersion time in the latex can be 10–600 s; preferably 20–100 s; more preferably 30–80 s.

[0105] Drying can be carried out in a vacuum drying oven.

[0106] Negative electrode preparation steps

[0107] A negative electrode material slurry is coated onto a negative electrode substrate to obtain a coated negative electrode substrate. The negative electrode material slurry comprises a negative electrode material and water. In some embodiments, the negative electrode material slurry consists of a negative electrode material and water. The composition of the negative electrode material and the selection of the negative electrode substrate are as described above and will not be repeated here. The amount of water used can be 3 to 15 parts by weight; preferably 5 to 10 parts by weight; more preferably 6 to 8 parts by weight.

[0108] In some embodiments, the following steps are also included: drying the negative electrode substrate coated with the negative electrode material slurry, and then pressing and cutting it to obtain the coated negative electrode substrate.

[0109] Drying can be carried out in an oven. The drying temperature can be 100–150°C; preferably 110–140°C; more preferably 120–130°C. The negative electrode substrate coated with the negative electrode material slurry passes through the oven at a speed of 1–6 m / min; preferably 2–5 m / min; more preferably 3–4 m / min.

[0110] Tableting can be performed on a double roller mill.

[0111] The negative electrode material slurry can be obtained by the following method: La-Y-Ni based hydrogen storage alloy powder and a conductive agent are mixed in a mixer equipped with steel balls to obtain a first mixture. The first mixture, negative electrode binder, yttrium oxide, and water are then slurried to obtain the negative electrode material slurry. Slurrying can be performed in a slurry mixer. Pre-mixing the La-Y-Ni based hydrogen storage alloy powder and the conductive agent can round the edges of the La-Y-Ni based hydrogen storage alloy powder and coat the conductive agent onto the surface of the La-Y-Ni based hydrogen storage alloy powder, thereby improving the discharge capacity and charge retention rate of the nickel-metal hydride battery.

[0112] The ball-to-material ratio in the mixer can be (0.5-6):1; preferably (1-4):1; more preferably (2-3):1.

[0113] The mixing time can be 15 to 50 hours; preferably 20 to 40 hours; more preferably 25 to 30 hours.

[0114] The pulping time can be 0.3 to 5 hours; preferably 0.5 to 3 hours; more preferably 1 to 2 hours.

[0115] The coated negative electrode substrate is softened and trimmed to obtain the negative electrode. Trimming and softening can be performed in a trimming and softening machine.

[0116] The length, width, and height of the negative electrode are as described above and will not be repeated here.

[0117] The negative electrode is immersed in an electrolyte containing a second electrolyte, then immersed in latex, and dried to obtain a gel-impregnated negative electrode. This process can improve the battery's charge retention rate.

[0118] The electrolyte containing the second electrolyte comprises the second electrolyte and water. In some embodiments, the electrolyte containing the second electrolyte consists of the second electrolyte and water.

[0119] The second electrolyte is composed of potassium hydroxide, sodium hydroxide, and lithium hydroxide in a weight ratio of 6–12:19–25:3.5–7.5. Preferably, the weight ratio of potassium hydroxide, sodium hydroxide, and lithium hydroxide in the second electrolyte is 7–10:20–24:4–7. More preferably, the weight ratio of potassium hydroxide, sodium hydroxide, and lithium hydroxide in the second electrolyte is 8–9:21–23:5–6.

[0120] The mass ratio of potassium hydroxide to water can be (6-12):(50-75); preferably (7-10):(55-70); more preferably (8-10):(55-60).

[0121] The soaking time in the electrolyte containing the second electrolyte can be 5 to 60 minutes; preferably 10 to 40 minutes; more preferably 20 to 30 minutes.

[0122] The latex can be a polytetrafluoroethylene (PTFE) latex or a styrene-butadiene rubber (SBR) latex; preferably a PTFE latex. The immersion time in the latex can be 10–100 s; preferably 20–80 s; more preferably 30–50 s.

[0123] Drying can be carried out in a vacuum drying oven.

[0124] Winding steps

[0125] The diaphragm is placed between the impregnated positive electrode and the impregnated negative electrode, and then wound into an electrode assembly; the electrode assembly is placed in a shell to obtain the first preform.

[0126] The diaphragm can be a sulfonated diaphragm, as described above.

[0127] The outer casing can be made of steel.

[0128] Steps for adding electrolyte

[0129] An electrolyte containing a third electrolyte is added to the first preform to obtain the second preform.

[0130] The electrolyte containing a third electrolyte comprises a third electrolyte and water. In some embodiments, the electrolyte containing a third electrolyte consists of a third electrolyte and water.

[0131] The third electrolyte is composed of potassium hydroxide, sodium hydroxide, and lithium hydroxide in a weight ratio of 6–12:19–25:3.5–7.5. Preferably, the weight ratio of potassium hydroxide, sodium hydroxide, and lithium hydroxide in the third electrolyte is 7–10:20–24:4–7. More preferably, the weight ratio of potassium hydroxide, sodium hydroxide, and lithium hydroxide in the third electrolyte is 8–9:21–23:5–6.

[0132] The mass ratio of potassium hydroxide to water can be (6-12):(50-75); preferably (7-10):(55-70); more preferably (8-10):(55-60).

[0133] The electrolyte containing the third electrolyte can be added to the first preform using a vacuum injection method. The electrolyte can be added in multiple stages; for example, 2 to 8 times, or 3 to 5 times.

[0134] The amount of electrolyte added can be 1 to 5 g; preferably 2 to 4 g; more preferably 2.5 to 3 g.

[0135] Pre-charging and sealing steps

[0136] The second pre-form is pre-charged to obtain the third pre-form. A cap is welded onto the third pre-form, and the cap is pressed into the outer casing to obtain the fourth pre-form. The fourth pre-form is heated to 40–75°C and then sealed to obtain a nickel-metal hydride battery.

[0137] An automatic charger can be used to precharge the second preform. The precharging current can be 0.5–2C; preferably 0.8–1.5C; more preferably 1–1.2C. The precharging time can be 1–10 min; preferably 2–8 min; more preferably 3–5 min.

[0138] The fourth pre-process is heated to 40–75°C; preferably, the fourth pre-process is heated to 45–65°C; more preferably, the fourth pre-process is heated to 45–55°C.

[0139] The applicant discovered that pre-charging the battery before sealing, combined with a high-temperature sealing process, can significantly improve the battery's charge retention rate. This may be because such a step avoids excessive internal pressure in the battery under charged conditions, which could lead to battery leakage and a decrease in charge retention rate.

[0140] The testing method is described below:

[0141] Discharge capacity: Charge at 380mA for 6 hours, let stand for 15 minutes, and then discharge at 380mA to 1.0V.

[0142] Charge retention: Place the nickel-metal hydride battery in an oven at 25°C for 2 hours, charge it at 380mA for 6 hours, let it stand for 90 days, and then discharge it at 380mA to 1.0V.

[0143] The raw materials are described below:

[0144] La-Y-Ni based hydrogen storage alloy powder has the following composition: La 0.4 Ce 0.2 Y 1.4 Ni 6.5 Mn 0.4 Al 0.3 Co 0.2 .

[0145] Sulfonated diaphragm: Purchased from Laizhou Lianyou Jinhao New Material Co., Ltd.

[0146] The electrolyte containing the first electrolyte, the electrolyte containing the second electrolyte, and the electrolyte containing the third electrolyte have the same composition and formula, consisting of potassium hydroxide, sodium hydroxide, lithium hydroxide, and water.

[0147] Examples 1-5

[0148] (1) The nickel-containing material, zinc oxide, and cobalt hydroxide are mixed in a three-dimensional mixer for time t1, and then the positive electrode binder is added and the mixing continues for time t2 to obtain the positive electrode material. The nickel-containing material consists of 78 parts by weight of cobalt-coated spherical nickel hydroxide and 22 parts by weight of nickel hydroxide.

[0149] The nickel foam is pre-pressed and tabs are formed. Then, polytetrafluoroethylene (PTFE) is coated onto the surface of the nickel foam to obtain coated nickel foam. The positive electrode material is brushed onto the coated nickel foam using a brush, and the thickness is controlled by a scraper. Then, it is rolled and cut to obtain the coated positive electrode substrate.

[0150] The coated positive electrode substrate is softened and trimmed to obtain the positive electrode.

[0151] The positive electrode is immersed in an electrolyte containing the first electrolyte, and then immersed in a polytetrafluoroethylene emulsion; the positive electrode after being immersed in the polytetrafluoroethylene emulsion is dried in a vacuum drying oven to obtain a gel-impregnated positive electrode.

[0152] (2) The La-Y-Ni hydrogen storage alloy powder and the conductive agent are mixed in a mixer with steel balls to obtain a first mixture; the first mixture, the negative electrode binder, yttrium oxide and deionized water are pulped in a pulper to obtain a negative electrode material slurry.

[0153] The negative electrode material slurry is coated onto a nickel-plated steel strip and then dried in an oven. The dried nickel-plated steel strip is then pressed into sheets using a roller mill and cut to obtain the coated negative electrode substrate.

[0154] The coated negative electrode substrate is softened and trimmed to obtain the negative electrode.

[0155] The negative electrode is immersed in an electrolyte containing a second electrolyte, and then immersed in a polytetrafluoroethylene emulsion; the negative electrode after being immersed in the polytetrafluoroethylene emulsion is dried in a vacuum drying oven to obtain a gel-impregnated negative electrode.

[0156] (3) Place the sulfonated diaphragm between the impregnated positive electrode and the impregnated negative electrode, align the widths of the impregnated positive electrode and the impregnated negative electrode, and then wind them into an electrode assembly; place the electrode assembly in a steel shell to obtain the first pre-product.

[0157] (4) The electrolyte containing the third electrolyte is added to the first pre-product in three batches using a vacuum injection method to obtain the second pre-product.

[0158] (5) The second pre-product is pre-charged with a current of 1C using an automatic charger to obtain the third pre-product.

[0159] (6) Weld a cap onto the third preform and press the cap into the steel outer shell to obtain the fourth preform. Heat the fourth preform to temperature T and then seal it on an automatic sealing machine to obtain a nickel-metal hydride battery.

[0160] Specific parameters are shown in Table 1. The performance of the resulting nickel-metal hydride battery is shown in Table 2.

[0161] Table 1

[0162]

[0163]

[0164] Comparative Example 1

[0165] Except for the nickel-containing material being cobalt-coated spherical nickel hydroxide, the rest is the same as in Example 1. The performance of the resulting nickel-metal hydride battery is shown in Table 2.

[0166] Comparative Example 2

[0167] Except that the cathode material does not contain cobalt hydroxyl oxide, the process is the same as in Example 1. The performance of the resulting nickel-metal hydride battery is shown in Table 2.

[0168] Comparative Example 3

[0169] Except for replacing yttrium oxide in the negative electrode slurry with zinc oxide, the process was the same as in Example 1. The performance of the resulting nickel-metal hydride battery is shown in Table 2.

[0170] Table 2

[0171]

[0172] This invention is not limited to the above-described embodiments. Any modifications, improvements, or substitutions that can be conceived by those skilled in the art without departing from the essential content of this invention fall within the scope of this invention.

Claims

1. A nickel-metal hydride battery, characterized in that, The nickel-metal hydride battery includes a positive electrode and a negative electrode; the positive electrode includes a positive electrode substrate and a positive electrode material loaded on the positive electrode substrate, and the negative electrode includes a negative electrode substrate and a negative electrode material loaded on the negative electrode substrate; The positive electrode material comprises 90-97 parts by weight of nickel-containing material, 1.5-4 parts by weight of metal oxide, 3-5 parts by weight of cobalt hydroxide, and a positive electrode binder; the nickel-containing material comprises cobalt-coated spherical nickel hydroxide and nickel hydroxide, and the metal oxide is zinc oxide; based on the nickel-containing material, the content of cobalt-coated spherical nickel hydroxide is 65-85 wt%, and the content of nickel hydroxide is 15-30 wt%. The negative electrode material comprises 85-94 parts by weight of La-Y-Ni hydrogen storage alloy, 0.2-0.9 parts by weight of conductive agent, negative electrode binder, and 0.2-1.0 parts by weight of yttrium oxide; The La-Y-Ni hydrogen storage alloy has the following composition: RE x AND y Neither d Mn a To the b M c RE is selected from one or more of La, Ce, Pr, and Nd, and must contain La; M is Co; Where 0.5≤x≤0.8, x+y=2, 0.2≤a≤0.6, 0.2≤b≤0.4, 0.1≤c≤0.3, 7.2≤a+b+c+d≤7.7; x, y, a, b, c, and d represent the molar fractions of each element.

2. The nickel-metal hydride battery according to claim 1, characterized in that, The positive electrode substrate is nickel foam, the negative electrode substrate is nickel-plated steel strip, the positive electrode binder is selected from one or more of sodium carboxymethyl cellulose, polytetrafluoroethylene or styrene-butadiene rubber, the negative electrode binder is selected from one or more of polytetrafluoroethylene, styrene-butadiene rubber or sodium carboxymethyl cellulose, and the conductive agent is selected from one or two of carbon black or graphene.

3. The nickel-metal hydride battery according to claim 1, characterized in that: The amount of positive electrode binder is 2 to 7 parts by weight; The amount of negative electrode binder is 8 to 14 parts by weight; The La-Y-Ni hydrogen storage alloy is used in powder form, with at least a portion of the conductive agent coated on the surface of the La-Y-Ni hydrogen storage alloy powder.

4. The nickel-metal hydride battery according to claim 1, characterized in that, A positive electrode adhesive layer containing a first electrolyte is formed on the surface of the positive electrode to obtain an impregnated positive electrode; wherein the positive electrode adhesive layer is mainly formed of polytetrafluoroethylene or styrene-butadiene rubber, and the first electrolyte is composed of potassium hydroxide, sodium hydroxide and lithium hydroxide in a weight ratio of 6-12:19-25:3.5-7.

5.

5. The nickel-metal hydride battery according to claim 4, characterized in that, A negative electrode adhesive layer containing a second electrolyte is formed on the surface of the negative electrode to obtain an impregnated negative electrode; wherein the negative electrode adhesive layer is mainly formed of polytetrafluoroethylene or styrene-butadiene rubber, and the second electrolyte is composed of potassium hydroxide, sodium hydroxide and lithium hydroxide in a weight ratio of 6-12:19-25:3.5-7.

5.

6. The nickel-metal hydride battery according to claim 5, characterized in that, The nickel-metal hydride battery also includes an electrolyte containing a third electrolyte, which is composed of potassium hydroxide, sodium hydroxide and lithium hydroxide in a weight ratio of 6-12:19-25:3.5-7.

5.

7. The nickel-metal hydride battery according to claim 6, characterized in that, The nickel-metal hydride battery also includes a separator and a casing; The membrane is located between the impregnated negative electrode and the impregnated positive electrode, and the membrane is selected from one or more of sulfonated membranes, fluorinated membranes, or grafted membranes. The impregnated positive electrode, impregnated negative electrode, separator, and electrolyte are located inside the outer casing.

8. A method for preparing a nickel-metal hydride battery, characterized in that, Includes the following steps: (1) Provide a positive electrode material comprising 90-97 parts by weight of nickel-containing material, 1.5-4 parts by weight of metal oxide, 3-5 parts by weight of cobalt hydroxyl oxide and positive electrode binder; coat the positive electrode material onto a positive electrode substrate to obtain a coated positive electrode substrate; soften and trim the coated positive electrode substrate to obtain a positive electrode; immerse the positive electrode in an electrolyte containing a first electrolyte, then immerse it in latex, and dry it to obtain a latex-impregnated positive electrode; The nickel-containing material includes cobalt-coated spherical nickel hydroxide and nickel hydroxide, and the metal oxide is zinc oxide; based on the nickel-containing material, the content of cobalt-coated spherical nickel hydroxide is 65-85 wt%, and the content of nickel hydroxide is 15-30 wt%. (2) The negative electrode material slurry is coated onto the negative electrode substrate to obtain the coated negative electrode substrate. The coated negative electrode substrate is softened and trimmed to obtain the negative electrode. The negative electrode is immersed in an electrolyte containing the second electrolyte, and then immersed in latex. After drying, the latex-impregnated negative electrode is obtained. The negative electrode slurry includes negative electrode material and water; the negative electrode material includes 85-94 parts by weight of La-Y-Ni hydrogen storage alloy, 0.2-0.9 parts by weight of conductive agent, negative electrode binder and 0.2-1.0 parts by weight of yttrium oxide; The La-Y-Ni hydrogen storage alloy has the following composition: RE x AND y Neither d Mn a To the b M c RE is selected from one or more of La, Ce, Pr, and Nd, and must contain La; M is Co; Where 0.5≤x≤0.8, x+y=2, 0.2≤a≤0.6, 0.2≤b≤0.4, 0.1≤c≤0.3, 7.2≤a+b+c+d≤7.7; x, y, a, b, c, and d represent the molar fractions of each element. (3) Place the diaphragm between the impregnated positive electrode and the impregnated negative electrode, and then wind it into an electrode assembly; place the electrode assembly in the shell to obtain the first pre-product; (4) Add the electrolyte containing the third electrolyte to the first pre-product to obtain the second pre-product; (5) Precharge the second pre-product to obtain the third pre-product; (6) Weld the cap onto the third preform and press the cap into the outer shell to obtain the fourth preform; heat the fourth preform to 40-75°C and then seal it to obtain a nickel-hydrogen battery.

9. The preparation method according to claim 8, characterized in that: In step (1), the positive electrode substrate is nickel foam, the negative electrode substrate is nickel-plated steel strip, and the positive electrode binder is selected from one or more of sodium carboxymethyl cellulose, polytetrafluoroethylene or styrene-butadiene rubber; the first electrolyte is composed of potassium hydroxide, sodium hydroxide and lithium hydroxide in a weight ratio of 6-12:19-25:3.5-7.

5. In step (2), the negative electrode binder is selected from one or more of polytetrafluoroethylene, styrene-butadiene rubber or sodium carboxymethyl cellulose, and the conductive agent is selected from one or two of carbon black and graphene; the second electrolyte is composed of potassium hydroxide, sodium hydroxide and lithium hydroxide in a weight ratio of 6-12:19-25:3.5-7.

5. In step (4), the third electrolyte in the electrolyte containing the third electrolyte is composed of potassium hydroxide, sodium hydroxide and lithium hydroxide in a weight ratio of 6-12:19-25:3.5-7.5.

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