Alkaline electrochemical cells with increased zinc oxide levels

Abstract

This invention provides an alkaline electrochemical battery, wherein at least the free electrolyte solution contains dissolved zinc oxide or zinc hydroxide, and / or the anode contains solid zinc oxide or zinc hydroxide to slow down the formation of a zinc oxide passivation layer on the zinc electrode. Furthermore, this invention also provides a method for preparing the alkaline electrochemical battery.

Description

[0001] Cross-referencing

[0002] This application claims priority to U.S. Provisional Application No. 62 / 795,750, filed January 23, 2019, and U.S. Patent Application No. 16 / 674,828, filed November 5, 2019, the entire contents of which are incorporated herein by reference. Technical Field

[0003] Alkaline electrochemical batteries are commercially available, typically in sizes LR6 (AA), LR03 (AAA), LR14 (C), and LR20 (D). Alkaline electrochemical batteries are cylindrical and must conform to size standards set by organizations such as the International Electrotechnical Commission (IEC). Consumers use electrochemical batteries to power various electronic devices, such as clocks, radios, toys, video games, movie cameras containing flash units, and digital cameras. These electronic devices have a wide range of discharge conditions, from low to high discharge. Due to the increasing use of high-discharge devices (such as digital cameras), there is a demand for manufacturers to produce batteries with high discharge characteristics.

[0004] Because the shape and size of batteries are typically fixed, battery manufacturers must modify battery characteristics to provide improved performance. To address how to improve battery performance in a specific device (such as a digital camera), it is often necessary to change the battery's internal structure. For example, this can be achieved by altering the battery structure by increasing the amount of active material used within the battery.

[0005] Zinc (Zn) is a well-known substance commonly used as the anode active material in electrochemical batteries (such as dry cell batteries). During the discharge of an electrochemical battery, zinc is oxidized to form zinc oxide (ZnO). The oxidation products of zinc form a passivation layer, which inhibits the effective discharge of remaining zinc and reduces battery performance.

[0006] The embodiments of the present invention are intended to overcome the limitations of the aforementioned related batteries. Summary of the Invention

[0007] One embodiment of the present invention provides an alkaline electrochemical battery comprising:

[0008] a) Container; and

[0009] b) An electrode assembly disposed within the container, the electrode assembly comprising a cathode, an anode, a partition located between the cathode and the anode, and a free electrolyte solution;

[0010] The anode comprises 1) solid zinc and 2) solid zinc oxide or solid zinc hydroxide; and

[0011] The free electrolyte solution contains dissolved zinc oxide or dissolved zinc hydroxide. Attached Figure Description

[0012] Figure 1 This is a cross-sectional schematic diagram of an embodiment of the alkaline electrochemical battery of the present invention.

[0013] Figure 2A and 2B The images are photographs of the control anode and the anode described according to the embodiments of this application, respectively.

[0014] Figure 3A and 3B They are respectively Figure 2A and 2B A close-up of the photo. Detailed Implementation

[0015] Various embodiments of the invention will now be described more fully with reference to the accompanying drawings. Only a portion of the embodiments of this application are shown in the specification, not all of them. In fact, various embodiments of the invention can be embodied in many different forms and should not be construed as being limited to the embodiments given in this specification. These embodiments provided in the specification are merely to enable this application to meet applicable legal requirements, wherein the same reference numerals always denote the same elements.

[0016] In the following description, various elements may be identified as having specific values ​​or parameters; however, these terms are merely exemplary. In fact, the exemplary embodiments do not limit the aspects and concepts of the embodiments, as many comparable parameters, sizes, ranges, and / or values ​​can be implemented. The terms “first,” “second,” “primary,” “exemplary,” “minor,” etc., do not indicate any order, quantity, or importance, but are used to distinguish individual elements. Furthermore, the terms “a,” “an,” and “the” do not indicate a limitation on quantity, but rather indicate that “at least one” of the referenced terms exists.

[0017] Each embodiment disclosed in this specification is applicable to each of the other embodiments disclosed. All combinations and sub-combinations of the various elements described in this specification are within the scope of the embodiments.

[0018] It is understood that, where parameter ranges are provided, all integers and ranges within the range, as well as their tenths and hundredths, are also provided by the embodiments. For example, "5-10%" includes: 5%, 6%, 7%, 8%, 9%, and 10%; 5.0%, 5.1%, 5.2%...9.8%, 9.9%, and 10.0%; 5.00%, 5.01%, 5.02%...9.98%, 9.99%, and 10.00%, and 6-9%, 5.1%-9.9%, and 5.01%-9.99%.

[0019] As used in this description, “about” in the context of a numerical value or range means within ±10% of the stated or claimed numerical value or range.

[0020] In this manual, "total battery electrolyte mass" refers to the total mass of the electrolyte in the battery, and "total battery electrolyte concentration" refers to the total concentration of the electrolyte in the battery. The total battery electrolyte concentration can be calculated as (total battery electrolyte mass) / (total battery electrolyte mass + total water mass in the battery) multiplied by 100 (if expressed as a percentage). The total additive weight percentage in the total battery electrolyte solution can be determined by calculating (total additive mass in the battery) / (total additive mass in the battery + total battery electrolyte mass + total water mass in the battery) x 100.

[0021] The "total weight percentage" of zinc compound or its portion in the battery, as used in this specification, refers to the ratio of the total weight of zinc compound to the total mass or weight or portion thereof of zinc compound, electrolyte, and water in the battery. For example, the "total zinc oxide weight percentage" of the battery is calculated as (mass of zinc oxide) / (mass of zinc oxide + mass of electrolyte + mass of water) x 100%.

[0022] The "total dissolved zinc oxide weight percentage" in the full-cell electrolyte is calculated as (mass of dissolved zinc oxide in the battery) / (mass of dissolved zinc oxide in the battery + mass of electrolyte in the battery + mass of water in the battery) x 100%. This measurement does not take into account the mass of solid (i.e. undissolved) zinc oxide in the anode.

[0023] In this specification, the "electrolyte concentration percentage" of the electrode refers to the ratio of the total weight of the electrolyte in the electrode to the total weight of the electrolyte and water in the electrode. For example, the "KOH weight percentage" of the electrode is calculated as (mass of KOH in the electrode) / (mass of KOH in the electrode + mass of water in the electrode) x 100%.

[0024] In this specification, "improvement" in specific capacity means an increase in specific capacity. Generally, "improvement" in the performance or performance indicators of a material or electrochemical battery means that the performance or performance indicators are different from those of different materials or electrochemical batteries, so that the user or manufacturer of the material or battery deems it satisfactory (e.g., lower cost, longer duration, more power, greater durability, easier or faster manufacturing, etc.).

[0025] In this specification, "specific capacity" refers to the total amount of charge in an electrochemical cell when discharged at a specific rate, usually measured in ampere-hours.

[0026] In this manual, "running time" refers to the length of time that an electrochemical cell can provide a certain level of charge.

[0027] In this specification, describing a solution as “saturated with X%” means that, under the same temperature, pressure, and other conditions, the solution contains a maximum amount of solute that can dissolve in the solution, taking into account all other components of the solution (such as dissolved electrolytes).

[0028] Describing an electrochemical cell as having a "total cell saturation of X%" takes into account both compounds dissolved in the free electrolyte solution and compounds present in the anode. For example, when calculating the total cell saturation of zinc oxide in an electrochemical cell, it is necessary to determine the amount of zinc oxide dissolved in the free electrolyte solution, as well as the amount of solid and dissolved zinc oxide in the anode, which may result in a total cell saturation percentage exceeding 100%.

[0029] In this instruction manual, "zinc ion source" refers to a source that generates zinc ions (Zn(OH)4) when placed in a solution. 2- Any compound of zinc ion source, non-limiting examples of which include Zn, zinc oxide (ZnO), and zinc hydroxide (Zn(OH)2). In one embodiment of the invention, the zinc ion source may refer only to ZnO and Zn(OH)2.

[0030] One embodiment of the present invention provides an alkaline electrochemical battery comprising:

[0031] a) Container; and

[0032] b) An electrode assembly disposed within the container, the electrode assembly comprising a cathode, an anode, a partition located between the cathode and the anode, and a free electrolyte solution;

[0033] The anode comprises 1) solid zinc and 2) solid zinc oxide or solid zinc hydroxide; and

[0034] The free electrolyte solution contains dissolved zinc oxide or dissolved zinc hydroxide.

[0035] According to one embodiment of the present invention, the anode comprises solid zinc oxide, and the free electrolyte solution comprises dissolved zinc oxide.

[0036] According to one embodiment of the invention, the free electrolyte solution contains greater than 2.0 wt% dissolved zinc oxide. According to another embodiment of the invention, the free electrolyte solution contains about 4.0-6.5 wt% dissolved zinc oxide.

[0037] According to one embodiment of the invention, the anode comprises a gel electrolyte, wherein the gel electrolyte is prepared by combining a gelling agent with a first aqueous alkaline electrolyte solution, wherein the first aqueous alkaline electrolyte solution comprises an alkali metal hydroxide electrolyte and dissolved zinc oxide. According to one embodiment of the invention, the first aqueous alkaline electrolyte solution comprises dissolved zinc oxide at a weight percentage of ≥2.5, ≥2.6, ≥2.7, ≥2.8, ≥2.9, ≥3.0, ≥3.1, ≥3.2, ≥3.3, ≥3.4, ≥3.5, ≥3.6, ≥3.7, ≥3.8, ≥3.9, or ≥4.0%. According to one embodiment of the invention, the first aqueous alkaline electrolyte solution comprises about 2.7-3.3 wt% dissolved zinc oxide.

[0038] According to one embodiment of the present invention, the cathode comprises a second aqueous alkaline electrolyte solution, wherein the second aqueous alkaline electrolyte solution comprises an alkali metal hydroxide electrolyte and dissolved zinc oxide. According to one embodiment of the present invention, the second aqueous alkaline electrolyte solution comprises dissolved zinc oxide in a weight percentage of ≥2.5, ≥2.6, ≥2.7, ≥2.8, ≥2.9, ≥3.0, ≥3.1, ≥3.2, ≥3.3, ≥3.4, ≥3.5, ≥3.6, ≥3.7, ≥3.8, ≥3.9, or ≥4.0%. According to one embodiment of the present invention, the second aqueous alkaline electrolyte solution comprises about 2.5-4.0 wt% or about 2.7-3.3 wt% of dissolved zinc oxide.

[0039] According to one embodiment of the present invention, the first aqueous alkaline electrolyte solution and the second aqueous alkaline electrolyte solution are the same.

[0040] According to one embodiment of the present invention, the total weight percentage of dissolved zinc oxide in the full-cell electrolyte solution of the electrochemical battery is about 1.5-4.5% by weight. According to one embodiment of the present invention, the total weight percentage of zinc oxide in the full-cell electrolyte solution of the electrochemical battery is about 2.0-4.0 or about 2.5-3.5% by weight. According to one embodiment of the present invention, the total weight percentage of zinc oxide in the full-cell electrolyte solution of the electrochemical battery is greater than about 4.5% by weight. According to one embodiment of the present invention, the total weight percentage of zinc oxide in the full-cell electrolyte solution of the electrochemical battery is about 0.5-4.5% by weight, or about 0.5-3.0% by weight, or about 0.5-2.0% by weight.

[0041] According to one embodiment of the present invention, the full-cell electrolyte of the electrochemical battery is more than 40% saturated with dissolved zinc oxide.

[0042] According to one embodiment of the present invention, the solid zinc oxide or solid zinc hydroxide is a substituted solid zinc oxide, which is substituted and contains a cationic substituent or an anionic substituent, wherein the substituted solid zinc oxide or the substituted solid zinc hydroxide is less soluble than the unsubstituted solid zinc oxide or the unsubstituted solid zinc hydroxide.

[0043] According to one embodiment of the present invention, the substituted solid zinc oxide has the formula Zn 1-x Y x O, wherein Y is at least one cationic substituent, and 0 < x ≤ 0.50.

[0044] According to one embodiment of the present invention, the substituted solid zinc hydroxide has the formula Zn 1-x Y x (OH)2, wherein Y is at least one cationic substituent, and 0 < x ≤ 0.50.

[0045] According to one embodiment of the present invention, the substituted solid zinc oxide has the formula ZnO 1-w A (2w / z) , wherein A is at least one anionic substituent, 0 < w ≤ 0.50, and z is the charge of the anionic substituent.

[0046] According to one embodiment of the present invention, the substituted solid zinc hydroxide has the formula Zn(OH) 2-w A (w / z) , wherein A is at least one anionic substituent, 0 < w ≤ 0.50, and z is the charge of the anionic substituent.

[0047] According to one embodiment of the present invention, the substituted solid zinc oxide has the formula Zn 1-x Y x O 1-w (OH) 2w , wherein Y is at least one cationic substituent, 0 < x ≤ 0.50, and 0 < w ≤ 0.50.

[0048] According to one embodiment of the present invention, the substituted solid zinc oxide is a mixed oxide hydroxide of cationic substitution and anionic substitution. According to one embodiment of the present invention, the mixed oxide hydroxide of cationic substitution and anionic substitution has Zn 1-x Y x O 1-w-t (OH) 2w A (2t / z) , wherein Y is at least one cationic substituent, 0 < x ≤ 0.50, wherein A is at least one anionic substituent, 0 < w ≤ 0.50, 0 < t ≤ 0.50, and z is the charge of the anionic substituent.

[0049] According to one embodiment of the present invention, the cation substituent is selected from Mg, Ca, Bi, Ba, Al, Si, Be, Cd, Ni, Co, Sn, Sr or any combination thereof.

[0050] According to one embodiment of the present invention, the anionic substituent is selected from CO3. 2- PO4 3- Or a combination thereof.

[0051] According to one embodiment of the invention, the anode contains about 0.2 to 5 volume percent of solid zinc oxide, based on the total volume of the anode. According to one embodiment of the invention, the anode contains about 0.3 to 1.5 volume percent of solid zinc oxide, based on the total volume of the anode. According to one embodiment of the invention, the anode contains about 0.66 volume percent of solid zinc oxide, based on the total volume of the anode.

[0052] According to one embodiment of the present invention, the alkaline electrochemical battery contains about 3.0-8.8% of total zinc oxide by weight. According to one embodiment of the present invention, the alkaline electrochemical battery contains about 3.0-4.0%, about 4.0-5.0%, about 5.0-6.0%, about 6.0-7.0%, about 7.0-8.0%, or about 8.0-9.0% of total zinc oxide by weight. According to one embodiment of the present invention, the alkaline electrochemical battery contains more than about 3.0% of total zinc oxide by weight. According to one embodiment of the present invention, the alkaline electrochemical battery contains more than or equal to about 3.5%, 4.0%, 4.5%, 5.0%, 5.5%, 6.0%, 6.5%, 7.0%, 7.5%, 8.0%, or 8.5% of total zinc oxide by weight. According to one embodiment of the present invention, the alkaline electrochemical battery contains about 4.75% of total zinc oxide by weight.

[0053] According to one embodiment of the invention, the electrolyte concentration percentage of the anode is about 16.0-30.0%. According to one embodiment of the invention, the electrolyte concentration percentage of the anode is about 18.0-22.0%. According to one embodiment of the invention, the electrolyte concentration percentage of the anode is less than about 22.0%.

[0054] According to one embodiment of the present invention, the electrolyte concentration of the full cell is about 26.0-30.0%. According to another embodiment of the present invention, the electrolyte concentration of the full cell is less than 29.0%.

[0055] According to one embodiment of the present invention, the total battery saturation of zinc oxide or zinc hydroxide is at least about 40%. According to one embodiment of the present invention, the total battery saturation of zinc oxide or zinc hydroxide is at least about 40-125%. According to one embodiment of the present invention, the total battery saturation of zinc oxide or zinc hydroxide is about 40-125%. According to one embodiment of the present invention, the total battery saturation of zinc oxide or zinc hydroxide is at least about 40%, 45%, 50%, 55%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, 100%, 105%, 110%, 115%, 120%, or 125%.

[0056] According to one embodiment of the present invention, the electrochemical cell is a primary cell. According to other embodiments of the present invention, the electrochemical cell is a secondary cell.

[0057] According to one embodiment of the present invention, the free electrolyte solution contains potassium hydroxide (KOH), sodium hydroxide (NaOH), lithium hydroxide (LiOH), magnesium hydroxide (Mg(OH)2), calcium hydroxide (Ca(OH)2), magnesium perchlorate (Mg(ClO4)2), magnesium chloride (MgCl2), or magnesium bromide (MgBr2).

[0058] According to one embodiment of the invention, the specific capacity or operating time of the alkaline electrochemical battery is greater than that of a similar alkaline electrochemical battery lacking dissolved zinc oxide in the free electrolyte. According to one embodiment of the invention, the specific capacity or operating time is greater than 1% to greater than 100%, or greater than 5% to greater than 90%, or greater than 10% to greater than 80%, or greater than 15% to greater than 70%, or greater than 20% to greater than 60%, or greater than 25% to greater than 50%, or greater than 30% to greater than 40%.

[0059] According to one embodiment of the present invention, the voltage of the battery is 0.1V-2.0V, 0.2V-1.9V, 0.3V-1.8V, 0.4V-1.7V, 0.5V-1.6V, 0.6V-1.5V, 0.7V-1.4V, 0.8V-1.3V, 0.9V-1.2V, 1.0V-1.1V, or 0.1V, 0.2V, 0.3V, 0.4V, 0.5V, 0.6V, 0.7V, 0.8V, 0.9V, 1.0V, 1.1V, 1.2V, 1.3V, 1.4V, 1.5V, 1.6V, 1.7V, 1.8V, 1.9V, or 2.0V.

[0060] The following is for reference Figure 1 The various embodiments of the present invention are described in detail below. Figure 1The diagram shown is a cross-sectional view of a cylindrical battery 1. The battery has a nail-shaped or spool-shaped structure and its dimensions are comparable to those of a conventional LR6(AA) alkaline battery, which is particularly suitable for this embodiment. However, it should be understood that, as those skilled in the art will know, according to other embodiments of the invention, the battery may have other sizes and shapes (such as prismatic or button-shaped) and electrode structures. Figure 1 The materials and designs of the electrochemical battery elements shown are for illustrative purposes only and may be substituted with other materials and designs. Furthermore, in some embodiments of the invention, the cathode and anode materials may be coated onto the surfaces of the separator and / or current collector and rolled up to form a “wound” structure.

[0061] Figure 1 The electrochemical cell 1 shown includes a container 10 having a closed bottom end 24, a top end 22, and a sidewall 26 located therebetween. The closed bottom end 24 includes a terminal cap 20 with a protrusion. The container 10 has an inner wall 16. Figure 1 In the illustrated embodiment, the positive terminal cap 20 is welded or otherwise connected to the bottom terminal 24. In one embodiment of the invention, the terminal cap 20 may be formed of plated steel with a protrusion in its central region. The container 10 may be formed of metal, such as steel, preferably plated internally with nickel, cobalt and / or other metals or alloys, or other materials, having sufficient structural characteristics to be compatible with the various inputs of the electrochemical cell. A label 28 may be formed around the outer surface of the container 10 and may be formed on the peripheral edges of the positive terminal cap 20 and the negative terminal cap 46, provided that the negative terminal cap 46 is electrically insulated from the container 10 and the positive terminal 20.

[0062] The container 10 contains a first electrode 18 and a second electrode 12, with a partition 14 between the first electrode 18 and the second electrode 12. The first electrode 18 is disposed within a space defined by the partition 14 fixed to the open end 22 of the container 10 and the sealing assembly 40. The closed end 24, the sidewall 26, and the sealing assembly 40 define a cavity for accommodating the battery electrode.

[0063] The sealing assembly 40 includes a sealing element 42 (such as a gasket), a current collector 44, and a conductive terminal 46 in electrical contact with the current collector 44. The sealing element 42 preferably includes a pressure relief hole that allows the sealing element 42 to rupture if the internal pressure of the battery becomes excessive. The sealing element 42 may be formed of a polymer or elastomeric material (such as nylon-6,6 or nylon-6,12), may be formed of an injection-molded polymer blend (such as a polypropylene matrix combined with polyphenylene ether or polystyrene), or other materials (such as metal), provided that the current collector 44 and the conductive terminal 46 are electrically insulated from the container 10 of the current collector, which serves as the second electrode 12. In the illustrated embodiment, the current collector 44 is an elongated, nail-shaped, or spool-shaped element. The current collector 44 is made of metal or metal alloy, such as copper or brass, conductively plated metal or plastic current collectors, etc., or may be made of other suitable materials. The current collector 44 is inserted through a hole in the sealing element 42, preferably located at the center of the sealing element 42.

[0064] The first electrode 18 is preferably a negative electrode or an anode. The negative electrode comprises a mixture of zinc (as an active material), a conductive material, solid zinc oxide, and a surfactant. The negative electrode may optionally include other additives, such as binders or gelling agents. Preferably, the volume of the active material used in the negative electrode is sufficient to maintain the desired particle-to-particle contact and the desired anode to cathode (A:C) ratio.

[0065] Throughout the battery's lifespan, particles should remain in contact with each other. If the volume of active material in the negative electrode is too low, the battery voltage may suddenly drop to unacceptably low values ​​when the battery is powering a device. This voltage drop is thought to be caused by a loss of continuity in the conductive matrix of the negative electrode. The conductive matrix can be formed from undischarged active material particles, conductive electrochemically formed oxides, or a combination thereof. A voltage drop may occur after oxide formation begins but before a sufficient network is established to bridge all the present active material particles.

[0066] The zinc used in the embodiments of this invention can be obtained from many different commercial sources under various names, such as BIA100 and BIA 115. Umicore SA, Brussels, Belgium is an example of a zinc supplier. According to a preferred embodiment of the invention, the zinc powder typically has 25% to 40% fine particles smaller than 75 μm, preferably 28% to 38% fine particles smaller than 75 μm. Generally, a lower percentage of fine particles will not achieve the required DSC service, while using a higher percentage of fine particles will lead to increased outgassing. A proper zinc alloy is required to reduce negative electrode outgassing of the battery and maintain test results.

[0067] The negative electrode contains a nonionic surfactant or anionic surfactant, or a combination thereof. According to one embodiment of the invention, the surfactant is a phosphate surfactant. It has been found that the anolyte resistance increases during discharge by adding solid zinc oxide alone, but decreases by adding a surfactant. As described above, the addition of a surfactant increases the surface charge density of solid zinc oxide and reduces the anolyte resistance. The use of a surfactant is believed to contribute to the formation of more porous discharge products when the surfactant is adsorbed onto solid zinc oxide. Anionic surfactants carry a negative charge, and in alkaline solutions, surfactants adsorbed on the surface of solid zinc oxide are believed to alter the surface charge density of the solid zinc oxide particles. It is believed that the adsorbed surfactant induces repulsive electrostatic interactions between the solid zinc oxide particles. It is believed that the surfactant reduces the increase in anolyte resistance caused by the addition of solid zinc oxide because the adsorbed surfactant on the solid zinc oxide leads to an increase in the surface charge density of the solid zinc oxide particles. The larger the BET surface area of ​​the solid zinc oxide, the more surfactant can be adsorbed onto the solid zinc oxide surface. According to one embodiment of the invention, the concentration of the surfactant relative to the electrode active material is approximately 5-50 ppm. According to one embodiment of the invention, the concentration of the surfactant is approximately 10-20 ppm.

[0068] According to one embodiment of the invention, the negative electrode contains about 0.2 to 5 wt% solid zinc oxide based on the total weight of the negative electrode. According to one embodiment of the invention, the negative electrode contains about 1 to 4 wt% solid zinc oxide. According to a preferred embodiment of the invention, the negative electrode contains about 0.3 to 1 wt% solid zinc oxide. According to a more preferred embodiment of the invention, the negative electrode contains about 0.66 wt% solid zinc oxide.

[0069] According to one embodiment of the invention, solid zinc oxide is substituted to reduce its solubility. According to one embodiment of the invention, a portion of the zinc in the solid zinc oxide is substituted with another cation. According to one embodiment of the invention, the substituted solid zinc oxide has the formula Zn. 1-x Y xO, wherein Y is at least one cationic substituent, 0 < x ≤ 0.50. According to one embodiment of the invention, the cationic substituent is selected from Mg, Ca, Bi, Ba, Al, Si, Be, Cd, Ni, Co, Sn, Sr, or any combination thereof. According to one embodiment of the invention, x is 0.01-0.40, or 0.02-0.35, or 0.4-0.30, or 0.05-0.25, or 0.10-0.20. According to one embodiment of the invention, x ≥ 0.01, ≥ 0.02, ≥ 0.04, ≥ 0.06, ≥ 0.08, ≥ 0.10, ≥ 0.12, ≥ 0.14, ≥ 0.16, ≥ 0.18, ≥ 0.20, ≥ 0.25, ≥ 0.3, ≥ 0.35, or ≥ 0.40.

[0070] According to one embodiment of the invention, a portion of the oxygen in solid zinc oxide is replaced by another anion. According to one embodiment of the invention, the substituted solid zinc oxide has the formula ZnO. 1-w A (2w / z) Wherein, A is at least one anionic substituent, 0 < w ≤ 0.50, and z is the charge of the anionic substituent. According to one embodiment of the present invention, the anionic substituent is selected from CO3. 2- PO4 3- Or a combination thereof. According to one embodiment of the invention, w is 0.01-0.40, or 0.02-0.35, or 0.4-0.30, or 0.05-0.25, or 0.10-0.20. According to one embodiment of the invention, w ≥ 0.01, ≥ 0.02, ≥ 0.04, ≥ 0.06, ≥ 0.08, ≥ 0.10, ≥ 0.12, ≥ 0.14, ≥ 0.16, ≥ 0.18, ≥ 0.20, ≥ 0.25, ≥ 0.30, ≥ 0.35, or ≥ 0.40. According to one embodiment of the invention, solid zinc oxide contains cationic and anionic substituents.

[0071] The aqueous alkaline electrolyte solution (or simply "electrolyte aqueous solution") contains an alkali metal hydroxide, such as potassium hydroxide (KOH), sodium hydroxide (NaOH), or a mixture thereof, preferably potassium hydroxide. The alkaline electrolyte used to form the gel electrolyte for the negative electrode contains about 16 to about 36 wt%, such as about 16 to about 28 wt%, particularly about 18 to about 22 wt%, or about 20 wt% of alkali metal hydroxide, based on the total weight of the alkaline electrolyte solution. According to one embodiment of the invention, the weight percentage of alkali metal hydroxide is 16-36 wt%. According to one embodiment of the invention, the weight percentage of alkali metal hydroxide is greater than or equal to 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, or 36. According to one embodiment of the invention, the weight percentage of the alkali metal hydroxide is less than or equal to 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, or 36. According to another embodiment of the invention, the weight percentage of the alkali metal hydroxide is equal to about 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, or 36.

[0072] Based on the total weight of the aqueous alkaline electrolyte solution, the aqueous alkaline electrolyte solution also contains approximately 1.5 to 4 wt% dissolved zinc oxide.

[0073] As is well known in the art, it is preferable to use a gelling agent, such as cross-linked polyacrylic acid (e.g., available from Noveon, Inc., Cleveland, Ohio, USA), in the negative electrode. 940). Carboxymethyl cellulose, polyacrylamide, and sodium polyacrylate are other gelling agents suitable for alkaline electrolyte solutions. The gelling agent is ideal to maintain a uniform dispersion of zinc and solid zinc oxide particles in the negative electrode. The amount of gelling agent present is chosen to achieve a low electrolyte separation rate without excessively high anode viscosity at yield stress, which could lead to anode distribution problems.

[0074] Dissolved zinc oxide is present in the anode, preferably dissolved in an aqueous electrolyte solution, to improve electroplating on spool-type or pin-type current collectors and reduce negative electrode stand-off venting. The added dissolved zinc oxide is separate from and distinct from the solid zinc oxide present in the anode composition. According to one embodiment of the invention, the content of dissolved zinc oxide is preferably 3-4 wt% based on the total weight of the negative electrode electrolyte solution. According to one embodiment of the invention, the dissolved zinc oxide in the negative electrode electrolyte solution is greater than 3 wt%. After degassing the zinc oxide at 150°C for about one hour, the BET surface area of ​​the soluble or dissolved zinc oxide is typically about 4 m² / g or less, measured using a Tristar 3000 BET surface area analyzer with multi-point calibration from Micrometrics; the particle size D50 (average diameter) is about 1 μm, measured using a CILAS particle size analyzer as shown above.

[0075] The negative electrode may optionally contain other components, including but not limited to: outgassing inhibitors, organic or inorganic corrosion inhibitors, electroplating agents, binders, or other surfactants. Examples of outgassing inhibitors or corrosion inhibitors include: indium salts (such as indium hydroxide), perfluoroalkyl ammonium salts, alkali metal sulfides, etc. According to a preferred embodiment of the invention, the sodium silicate content is approximately 0.3 wt% based on the total weight of the negative electrode electrolyte to substantially prevent the battery from short-circuiting through the separator during battery discharge.

[0076] As is known in the art, negative electrodes can be formed in a variety of different ways. For example, negative electrode components can be dry-mixed and added to the battery, alkaline electrolyte can be added separately, or a pre-gelled negative electrode process can be used according to a preferred embodiment of the invention.

[0077] According to one embodiment of the invention, zinc and solid zinc oxide powder, along with other optional powders besides a gelling agent, are combined and mixed. A surfactant is then introduced into the mixture containing zinc and solid zinc oxide. A pregel comprising an alkaline electrolyte solution, soluble zinc oxide, a gelling agent, and optional other liquid components is introduced into the surfactant, zinc, and solid zinc oxide mixture, and further mixed to obtain a substantially homogeneous mixture before addition to the battery. Alternatively, according to a preferred embodiment of the invention, solid zinc oxide is pre-dispersed in a negative electrode pregel comprising an alkaline electrolyte, a gelling agent, soluble zinc oxide, and other desired liquids, and mixed for approximately 15 minutes. Then, solid zinc oxide and a surfactant are added, and the negative electrode is mixed for an additional period of time, such as approximately 20 minutes. Based on the total weight of the negative electrode, the content of the gel electrolyte used in the negative electrode is typically from approximately 25 to approximately 35 wt%, such as approximately 32 wt%. Based on the total volume of the negative electrode, the volume percentage of the gel electrolyte may be approximately 70%.

[0078] In addition to the aqueous alkaline electrolyte absorbed by the gelling agent during the negative electrode manufacturing process, an additional aqueous solution of alkali metal hydroxide, i.e., "free electrolyte," is added to the battery during manufacturing. The free electrolyte can be incorporated into the battery by placing it in a cavity defined by the positive electrode, negative electrode, or a combination thereof. The method used to add the free electrolyte to the battery is not important, as long as it is in contact with the negative electrode, positive electrode, and separator. According to one embodiment of the invention, the free electrolyte is added both before and after the addition of the negative electrode mixture. According to one embodiment of the invention, approximately 0.97 g of a 34 wt% KOH solution is added as the free electrolyte to an LR6 type battery, and approximately 0.87 g is added to the cavity containing the separator before the negative electrode is inserted. After the negative electrode is inserted, the remaining 34 wt% KOH solution is injected into the cavity containing the separator. The free electrolyte solution contains approximately 0.01-6.0 wt% dissolved zinc oxide. According to one embodiment of the present invention, the free electrolyte solution contains greater than, less than or equal to, a weight percentage of about 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3... Dissolved zinc oxide in the following weight percentages: 0, 3.1, 3.2, 3, 3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, 5.0, 5.1, 5.2, 5.3, 5.4, 5.5, 5.6, 5.7 / 5.8, 5.9, 6.0, or dissolved zinc oxide in weight percentages between any two of the above values. According to a preferred embodiment of the invention, the free electrolyte solution contains about 4.0-6.0 wt% dissolved zinc oxide. The saturation of zinc oxide dissolved in the free electrolyte solution can be greater than or equal to approximately 50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59%, 60%, 61%, 62%, 63%, 64%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%.

[0079] The second electrode 12, also referred to herein as the positive electrode or cathode, comprises an electrochemically active material. Electrolytic manganese dioxide (EMD) is a commonly used electrochemically active material, and its content, based on the total weight of the positive electrode (i.e., EMD, conductive material, positive electrode electrolyte, and additives, including organic additives, if present), is typically about 80 to 92 wt%, preferably about 86 to 92 wt%. The positive electrode is formed by combining and mixing the desired components of the electrode, distributing a certain amount of the mixture to the open end of a container, and molding the mixture into a solid tubular structure using a pressure head. This solid tubular structure forms a cavity within the container, into which the partition 14 and the first electrode 18 are subsequently disposed. Figure 1 As shown, the second electrode 12 has a flange 30 and an inner surface 32. Alternatively, the positive electrode can be formed by pre-forming multiple rings from a mixture containing EMD and optional additives, and then inserting the rings into a container to form a tubular second electrode. Figure 1 The batteries shown typically consist of 3 or 4 rings.

[0080] The positive electrode may include other components, such as conductive materials (e.g., graphite), which, when mixed with the EMD, provide a conductive matrix substantially throughout the positive electrode. The conductive material may be natural (i.e., mined) or synthetic (i.e., manufactured). According to one embodiment of the invention, the ratio of active material or oxide to carbon (O:C ratio) in the positive electrode of the battery is about 12 to about 14. Too high an oxide to carbon ratio reduces the resistance of the container and cathode, affecting the overall battery resistance and potentially impacting high-speed testing (e.g., DSC testing) or higher cutoff voltages. Furthermore, the graphite may be expanded or non-expanded. Graphite suppliers for alkaline batteries include Timcal America of Westlake, Ohio; Superior Graphite Company of Chicago, Illinois; and Lonza, Ltd. of Basel, Switzerland. The content of conductive material is typically about 5 to about 10 wt% based on the total weight of the positive electrode. Excessive graphite reduces EMD input, thus decreasing battery capacity; insufficient graphite increases the contact resistance between the container and the cathode and / or the cathode resistance. An example of an additive is barium sulfate (BaSO4), commercially available from Bario E. Derivati ​​SpA in Massa, Italy. The barium sulfate content is typically from about 1 to about 2 wt% based on the total weight of the cathode. Other additives may include barium acetate, titanium dioxide, binders such as diacetylene, and calcium stearate.

[0081] According to one embodiment of the invention, a positive electrode component (such as EMD), a conductive material, and barium sulfate, along with optional one or more additives, are mixed together to form a homogeneous mixture. During mixing, an alkaline electrolyte solution (such as about 37% to about 40% KOH solution) and optionally including one or more organic additives are uniformly dispersed into the mixture to ensure uniform distribution of the solution throughout the positive electrode material. According to one embodiment of the invention, the alkaline electrolyte solution used to form the cathode contains dissolved zinc oxide in any amount up to saturation. The mixture is then added to a container and molded using a plunger. Before and after molding, moisture in the container and the positive electrode is mixed, and the composition of the mixture is preferably optimized to allow for the molding of a high-quality positive electrode. Optimization of the mixed moisture allows for positive electrode molding with minimal splashing due to wet mixing and minimal spalling and excessive tool wear due to dry mixing; optimization helps achieve the desired high cathode weight. The moisture content in the positive electrode mixture affects the overall battery electrolyte balance and has an impact on high-rate testing.

[0082] One parameter used by battery designers characterizes battery design as the ratio of the electrochemical capacity of one electrode to the electrochemical capacity of the other electrodes, such as the ratio of anode (A) to cathode (C), i.e., the A:C ratio. For an LR6 type alkaline galvanic cell using zinc in the negative or anode and MnO2 in the positive or cathode, the A:C ratio can be greater than 1.32:1, such as greater than 1.34:1. Specifically, for impact-molded cathodes, the A:C ratio is 1.36:1. The A:C ratio for ring-molded cathodes can be even lower, such as from about 1.3:1 to about 1.1:1.

[0083] A separator 14 is provided to separate the first electrode 18 from the second electrode 12. The separator 14 maintains physical dielectric separation between the electrochemically active materials of the positive and negative electrodes and allows ion transport between the electrode materials. Furthermore, the separator can serve as a wicking medium for the electrolyte and prevent fragments of the negative electrode from contacting the collar at the top of the positive electrode. The separator 14 can be a layered, ion-permeable nonwoven fabric; a typical separator typically comprises two or more layers of paper. Conventional separators are typically formed by pre-molding the separator material into a cup-shaped basket and then inserting it under a cavity defined by the second electrode 12 and the closed end 24, and any positive electrode material thereon; or, during battery assembly, by inserting two rectangular plates into the cavity, with the materials rotated 90 degrees relative to each other to form the basket. Conventional pre-molded separators are typically made from a nonwoven fabric sheet rolled into a cylindrical shape, the nonwoven fabric adapting to the inner wall of the second electrode and having a closed bottom end.

[0084] All references cited above, as well as all references cited in this specification, are incorporated herein by reference in their entirety.

[0085] While embodiments of the invention have been described and illustrated above, these descriptions should be considered illustrative or exemplary, not restrictive. It should be understood that those skilled in the art can make changes and modifications within the scope of the appended claims. In particular, embodiments of the invention may include any combination of features from the different embodiments described above and below.

[0086] The embodiments of the present invention are further described below through illustrative and non-limiting examples to better understand the embodiments and advantages of the present invention. The following embodiments are for illustrating preferred embodiments of the present invention. Those skilled in the art will understand that the technologies disclosed in the following embodiments represent the technologies used in the embodiments, which have played a good role in the implementation embodiments and can be considered as preferred modes of implementation. However, based on the disclosure of this application, those skilled in the art should understand that changes can be made to the specific embodiments disclosed in this application without departing from the spirit and scope of the embodiments, and similar or related results can still be obtained.

[0087] Discussion and Examples

[0088] As previously mentioned, the discharge of zinc-based batteries involves the oxidation of zinc in the anode, leading to the formation of zinc oxide. The oxidation products of zinc form a passivation layer, inhibiting the effective discharge of remaining zinc. The addition of dissolved ZnO (in the free electrolyte solution and the solution contained in the anode) and additional solid ZnO (in the anode) promotes the precipitation of the reaction products elsewhere. Preventing the passivation layer from coating the anode allows for better utilization of zinc, resulting in significantly improved run times for high-speed testing, particularly for digital camera (DSC) ANSI standard testing.

[0089] Furthermore, nickel-metal hydride (NiMH) chargers are not designed for charging primary alkaline batteries. Charging with NiMH can lead to abuse, causing battery leakage. Specifically, constant-current charging causes water decomposition, resulting in gas generation and increased internal pressure until a safety mechanism drains the electrolyte. Adding a zincate source (Zn(OH)4) 2- This allows the battery to apply a voltage-dependent current to prevent water decomposition and delay the possibility of leakage. This is achieved through embodiments of the invention, namely by saturating or near-saturating the electrolyte with dissolved zinc oxide, and further by adding additional zinc oxide as a solid to the anode formulation. A large amount of zinc oxide will further delay the possibility of water decomposition.

[0090] While most of the discussion in this specification pertains to the addition of zinc oxide to the electrode and electrolyte solution, other compounds that act as zincate ion sources may be used instead of zinc oxide. For example, in addition to zinc oxide, the embodiments described in this specification may include Zn(OH)₂ in the electrode and / or electrolyte solution.

[0091] Comparison of surface passivation in anodes with and without zinc oxide

[0092] Two anodes were prepared to compare the passivation in zinc oxide anodes with and without added solid zinc oxide. The compositions of the control anode and the target anode are shown in Table 1.

[0093] Table 1. Anode and free electrolyte compositions used for surface passivation comparison.

[0094] Reference anode Target anode wt% of ZnO dissolved in 28% anode KOH 1 3.44 Vol.% of solid ZnO 0 2.3 wt% of ZnO in the surrounding free electrolyte 0 5.6

[0095] After 56 and 76 minutes of testing with a digital camera (DSC), both anodes were discharged. Figure 2A (Reference anode) and Figure 2B The surface of the discharge anode can be seen in the (anode with added zinc oxide). It is clear that the discharge reaction and reaction products preferentially reside around the anode periphery, near the separator.

[0096] Figure 3A and 3B These are images of the reaction zones at higher magnifications for the control anode and the anode with added zinc oxide, respectively. At closer magnification, the zinc particles in the control anode are covered by ZnO (i.e., passivated). For the anode with added solid zinc oxide, the ZnO reaction products precipitate at nucleation sites introduced by the added solid zinc oxide. Therefore, the zinc surface remains clean and is available for discharge reaction. Higher ZnO content and presaturation increase the likelihood of precipitates forming away from the zinc surface.

[0097] Digital Camera (DSC) Test

[0098] To test the advantages of adding solid zinc oxide to the anode and dissolving zinc oxide in the electrolyte solution, digital camera scanning (DSC) tests were performed on multiple electrochemical cells to determine the time required to reduce the cell voltage to 1.05V. The results are shown in Table 2.

[0099] Table 1 DSC Test Results

[0100]

[0101] Adding zinc oxide to the electrolyte solution and anode separately (cells 2 and 3, respectively) has advantages compared to cell 1 (which contains 1 wt% ZnO in the electrolyte solution and has no added solid zinc oxide). However, the combination of both (in cell 4) shows a dramatic increase in performance during DSC testing. The interaction of these two added zinc oxides resulted in a 59% increase in the DSC test time compared to cell 1. The advantages shown in cells 2 and 3 could not have predicted this result.

[0102] Relationship between zinc oxide and potassium hydroxide levels and battery expansion

[0103] Corrosion from zinc in the electrodes can cause outgassing, increasing the internal pressure of the battery and potentially leading to swelling and rupture during storage or use. Corrosion can also reduce battery life. Batteries with high and low levels of zinc oxide and high and low levels of potassium hydroxide at the anode were compared to understand how relative levels affect the swelling of electrochemical cells. The total zinc oxide saturation percentage in the table below includes both zinc oxide actually dissolved in the electrolyte solution and solid zinc oxide in the anode, explaining why the percentage may exceed 100%. Batteries were prepared and then stored at 80°C for 8 weeks to simulate extended aging at room temperature. The swelling in each cell was observed in mils (1 / 1000 inch) as an alternative to directly measuring the internal pressure of the battery, and the results are shown in Table 3.

[0104] Table 3: Comparison of expansion in aged batteries with different levels of anolyte concentration and ZnO saturation.

[0105] Total ZnO saturation Anode KOH% Net expansion at 80℃ (mils) 65 28 0·9 110 28 3·8 65 20 0·3 110 20 1·7

[0106] For both higher and lower ZnO levels, lower KOH levels result in reduced cell expansion. Therefore, reducing the percentage of KOH in the anode allows for increased operating time, while increasing the ZnO level allows for better outgassing by mitigating the outgassing issues caused by the increase.

[0107] Many modifications and other embodiments can be conceived by those skilled in the art based on the description and accompanying drawings of this specification. Therefore, it should be understood that the embodiments of the present invention are not limited to those disclosed in this specification, and other modifications and embodiments should also be included within the scope of the appended claims and embodiments. Although certain terms are used in the specification, their use is merely general and descriptive and not for limiting purposes. For the embodiments described in this application, each embodiment disclosed in this specification is applicable to every other disclosed embodiment. For example, although this application primarily describes embodiments comprising solid and dissolved zinc oxide, embodiments in which all or some of the solid and / or dissolved zinc oxide is replaced by zinc hydroxide should also be considered within the scope of the embodiments.

Claims

1. An alkaline electrochemical battery, comprising: a) Container; as well as b) An electrode assembly disposed within the container, the electrode assembly comprising a cathode, an anode, a partition located between the cathode and the anode, and a free electrolyte solution; The anode comprises 1) solid zinc, 2) 0.2-5 wt% solid granular zinc oxide or solid granular zinc hydroxide; and 3) dissolved zinc oxide or dissolved zinc hydroxide. The free electrolyte solution contains dissolved zinc oxide or dissolved zinc hydroxide, the anode contains a gel electrolyte, the gel electrolyte is prepared by combining a gelling agent with a first aqueous alkaline electrolyte solution, the first aqueous alkaline electrolyte solution contains less than 30 wt% alkali metal hydroxide electrolyte and ≥2.5 wt% dissolved zinc oxide, and the alkaline electrochemical cell is a primary alkaline electrochemical cell.

2. The alkaline electrochemical battery according to claim 1, wherein, The anode comprises solid zinc oxide particles and dissolved zinc oxide, and the free electrolyte solution comprises dissolved zinc oxide.

3. The alkaline electrochemical battery according to claim 2, wherein, The free electrolyte solution contains 1.5-2.5 wt% dissolved zinc oxide.

4. The alkaline electrochemical battery according to claim 1, wherein, The cathode contains a second aqueous alkaline electrolyte solution, which contains an alkali metal hydroxide electrolyte and dissolved zinc oxide.

5. The alkaline electrochemical battery according to claim 4, wherein, The second aqueous alkaline electrolyte solution contains ≥2.5 wt% dissolved zinc oxide.

6. The alkaline electrochemical battery according to claim 1, wherein, In the full-cell electrolyte solution of the electrochemical cell, the total weight percentage of dissolved zinc oxide is 1.5-4.5 wt%.

7. The alkaline electrochemical battery according to claim 1, wherein, More than 40% of the total electrolyte of the electrochemical cell is saturated with dissolved zinc oxide.

8. The alkaline electrochemical battery according to claim 1, wherein, The solid zinc oxide or solid zinc hydroxide particles are substituted and contain cationic or anionic substituents, and the substituted solid zinc oxide or solid zinc hydroxide particles have lower solubility than the unsubstituted solid zinc oxide or solid zinc hydroxide particles.

9. The alkaline electrochemical battery according to claim 8, wherein, The substituted solid particulate zinc hydroxide has the formula Zn 1-x Y x O or Zn 1-x Y x (OH)2, wherein Y is at least one cationic substituent and 0 10. The alkaline electrochemical battery according to claim 8, wherein, The replaced solid zinc oxide particles have the formula ZnO 1- w A (2w / z) Or Zn(OH) 2-w A (w / z) Where A is at least one anionic substituent, 0 < w ≤ 0.50, and z is the charge of the anionic substituent.

11. The alkaline electrochemical battery according to claim 8, wherein, The substituted solid particle zinc oxide is a mixed oxide hydroxide of cationic substitution and anionic substitution, having the formula Zn 1-x Y x O 1-w-t (OH) 2w A (2t / z) , where Y is at least one cationic substituent, 0 < x ≤ 0.50, A is at least one anionic substituent if present, 0 < w ≤ 0.50, 0 < t ≤ 0.50, and z is the charge of the anionic substituent.

12. The alkaline electrochemical battery according to claim 8, wherein, If the cation substituent is present, it is selected from Mg, Ca, Bi, Ba, Al, Si, Be, Cd, Ni, Co, Sn, Sr, or any combination thereof; if the anion substituent is present, it is selected from CO3. 2- PO4 3- Or a combination thereof.

13. The alkaline electrochemical battery according to claim 2, wherein, The alkaline electrochemical cell contains 3.0-8.8 wt% total zinc oxide.

14. The alkaline electrochemical battery according to claim 2, wherein, The alkaline electrochemical cell contains more than 7.0 wt% total zinc oxide.

15. The alkaline electrochemical battery according to claim 2, wherein, The electrolyte concentration at the anode is 16.0-30.0% by percentage.

16. The alkaline electrochemical battery according to claim 1, wherein, The electrolyte concentration of the full cell is 26.0-30.0%.

17. The alkaline electrochemical battery according to claim 1, wherein, The total battery saturation of zinc oxide or zinc hydroxide is at least 40%.

18. The alkaline electrochemical battery according to claim 1, wherein, The specific capacity or operating time of the alkaline electrochemical battery is greater than that of an alkaline electrochemical battery lacking dissolved zinc oxide in the free electrolyte.

19. The alkaline electrochemical battery according to claim 1, wherein, The alkaline electrochemical cell is a galvanic cell.

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