KR102654722B1 - Cathode of Alkali Metal-Air Battery - Google Patents

Abstract

Metal-air batteries and component air cathodes include solid ion-conducting polymer materials.

Description

Cathode of Alkali Metal-Air Battery

The present invention relates generally to electrochemical batteries, and more particularly to metal-air batteries and their component cathodes.

A metal-air cell is an electrochemical cell that uses an anode made of a metal anode and oxygen from air as a cathode depolarizer (fuel). Because oxygen is not stored in the battery, the capacity and energy density of metal-air batteries can be very high. Specific energies for the zinc-air system and other metal-air battery systems are shown in Table 1. The specific energy of zinc-air batteries exceeds that of lithium ion by a large margin.

battery type theoretical specific energy
Wh/kg (including oxygen) theoretical specific energy
Wh/kg (oxygen excluded) open-circuit
Voltage, V aluminum-air 4300 8140 1.2 Calcium-Air 2990 4180 3.12 Magnesium-Air 2789 6462 2.93 potassium-air 935 1700 2.48 sodium-air 1677 2260 2.3 lithium-air 5210 11140 2.91 zinc-air 1090 1350 1.65 Lithium-ion battery Not applicable 265 3.8

During discharge, the anode of a metal-air cell undergoes oxidation reactions typical for that particular metal. The reaction mechanism is generally multistep and the intermediates depend on the electrolyte. Typical anode discharge reactions for alkaline zinc-air cells are expressed in equations (1-4).

Zn + 4OH ^- → Zn(OH) ₄ ^{2 -} + 2e ^- (1)

Zn + 2OH ^- → Zn(OH) ₂ + 2e ^- (2)

Zn + 2OH ^- → ZnO + H ₂ O + 2e ^- (3)

Zn(OH) ₂ → ZnO + H ₂ O (4)

The key component of all metal-air batteries is the air electrode. Unlike traditional battery cathodes, the air electrode can function primarily as a catalytic matrix for oxygen reduction, while oxygen is supplied from the air outside the battery, which is mainly atmospheric air, and also acts as a cathode current collector. The cathode reaction sequence for alkaline aqueous electrolytes is described by the following equations:

0 ₂ + 2e ^- + H ₂ O → 0 ₂ H ^- + OH ^- (5)

0 ₂ H ^- → OH ^- + 1/2 0 ₂ (6)

Because the oxygen is supplied from the outside air, the positive electrode itself can be very thin as it is needed only to conduct electrons and catalyze the oxygen to the hydroxyl reaction. Various carbons, potassium permanganate, manganese dioxide, cobalt tetrapyrazinoporphyrazine derivatives, perovskites, titanium doped manganese dioxide, cobalt oxide, graphene, Ketjen black, doped Ketjen black, carbon Nanotubes, carbon fibers, cobalt manganese oxide, conducting polymers and intrinsically conducting polymers, combinations thereof, and other compounds have been reported to promote the chemical decomposition of peroxides through reaction (6).

Typical air electrode cathode structures typically include multiple layers including an air diffusion layer, a hydrophobic PTFE layer, and a catalyst layer in which carbon is mixed with an active catalyst to improve peroxide decomposition. The cathode is separated from the anode by a separator and barrier layer, is wettable with respect to the electrolyte, and can prevent the metal anode from direct contact with the cathode.

Air holes facing the cathode are used to provide adequate air supply. Before a metal-air cell is required for use, it must be protected from the external environment. The adhesive and gas separator tabs covering the vent holes prevent most oxygen from freely entering the cell. The tab is removed before use, allowing the cathode to receive a free supply of air.

Zinc-air cells are one of the most commonly used metal-air systems. The battery exhibits higher energy density compared to alkaline batteries. Disadvantages of this system include relatively low speed performance and vulnerability to environmental conditions. Zinc-air cells generally perform well for low continuous current draws, but may provide inadequate service for intermittent and high-speed tests.

The zinc-air cell configuration is typically a coin cell design, which includes a bottom can with air pores, a cathode structure comprising hydrophobic and barrier layers and a separator thereon. Because the air electrode is thin, most of the cell volume is occupied by the zinc anode. Larger cells, typically prismatic, require complex air delivery systems to maintain proper performance. Cylindrical (e.g. AA or LR6 size) zinc-air designs generally result in cell costs that are too high for the alkaline category, complex cathode designs and manufacturing processes, air transfer paths, and cathode to positive terminal assemblies. Requires welding of the current collector.

Common primary zinc, manganese dioxide ("Zn/Mn0 ₂ ") or alkaline batteries provide good performance for a variety of tests, including intermittent testing, at low material and manufacturing costs. However, battery capacity and therefore lifespan is limited by the amount of electrochemically active ingredients such as MnO ₂ and zinc that can be filled into the cell.

The anode material and associated electrochemical reactions in zinc-air and air-assisted zinc-MnO ₂ cells are essentially the same as for Zn/MnO ₂ . However, in air-assisted batteries, also known as air recovery or air recovery batteries, the cathode can be recharged or restored by air. When the cell is not in use, or when the discharge rate is sufficiently low, atmospheric oxygen can enter the cell through the air pores, react with the air cathode, and recharge the manganese oxyhydrate back to dioxide:

1/2 0 ₂ + MnOOH → Mn0 ₂ + OH ^- (7)

At high discharge rates, the air-assisted battery can act like a conventional alkaline cell and reduce new manganese dioxide. The cathode can be wetted with electrolyte so that MnO ₂ reduction occurs. At the same time, a typical cathode must allow oxygen to enter since oxygen has low solubility in KOH solutions.

Air-assisted batteries are particularly useful in intermittent use applications and can provide significant performance improvements over traditional alkaline batteries. However, the design of air-assisted batteries is as complex as that of zinc-air cells, making them difficult and expensive to manufacture. Because of these limitations, no practical cylindrical air-assisted battery has been mass produced to date. Therefore, the need for ease of fabrication of batteries with low cost and improved run time in consumer applications remains unmet, and a need exists for metal-air batteries that can operate in intermittent and high-speed usage applications. .

According to one aspect, an electrochemical metal-air battery has an air electrode component comprising a solid ion-conducting polymer material, the solid ion-conducting polymer material being used in the air electrode and referred to in this application as a solid ion-conducting polymer material.

In one aspect, a metal-air battery includes: an air electrode comprising an electrically conductive material and a solid ion-conducting polymer material; a negative electrode comprising a first electrochemically active metal; and an ion-conducting, dielectric, non-electrochemically active material interposed between the air electrode and the negative electrode and in contact with the air electrode, wherein the air electrode is exposed to the oxygen gas source and when the battery is under load. , acts to reduce oxygen.

Other aspects of a metal-air battery may include one or more of the following:

The solid ion-conducting polymer material has a crystallinity greater than 30%;

The solid ion-conducting polymer material has a melting temperature;

The solid ion-conducting polymer material has a glassy state;

The solid ion-conducting polymer material has at least one cationic and anionic diffusing ion, and at least one diffusing ion is capable of moving within the glassy state;

The solid ion-conducting polymer material has a plurality of charge transfer complexes;

The solid ion-conducting polymer material includes a plurality of monomers, each charge transfer complex located on a monomer;

The electronic conductivity of the solid ion-conducting polymer material is less than 1×10 ^-8 S/cm at room temperature;

The glassy state exists at temperatures below the melting temperature of the solid ion-conducting polymer material; The at least one cationic diffusing ion comprises an alkali metal, alkaline earth metal, transition metal, or post-transition metal;

The solid ion-conducting polymer material includes a plurality of monomers, with at least one anionic diffusing ion present per monomer.

The solid ion-conducting polymer material includes a plurality of monomers, and there is at least one cationic diffusing ion per monomer;

There is at least 1 mole of cationic diffusing ions per liter of solid ion-conducting polymer material;

A charge transfer complex is formed by the reaction of a polymer, an electron acceptor, and an ionic compound, and each cationic and anionic diffusing ion is a reaction product of an ionic compound;

The solid ion-conducting polymer material is formed from at least one ionic compound, the ionic compound each comprising at least one cationic and anionic diffusing ion;

The solid ion-conducting polymer material is thermoplastic.

Charge transfer complexes are formed by the reaction of a polymer with an electron acceptor;

The melting temperature of the solid ion-conducting polymer material is higher than 250°C;

Each at least one cationic and anionic diffusing ion has a diffusivity, the cationic diffusivity being greater than the anionic diffusivity;

The cation transfer constant of the solid ion-conducting polymer material is greater than 0.5;

The solid ion-conducting polymer material contains lithium, and the concentration of lithium is greater than 3 moles of lithium per liter of the solid ion-conducting polymer material;

Cationic diffusing ions include lithium;

Diffusing cations are monovalent;

The valence of a diffusing cation is greater than 1;

The air cathode generates hydroxide ions when reducing oxygen, and the solid ion-conducting polymer material conducts hydroxide ions;

The diffusing anion is the hydroxide ion;

The diffusing anion is monovalent;

Both the diffusible anion and the diffusible cation are monovalent;

At least one of the cationic and anionic diffusing ions has a diffusivity, the anionic diffusivity being greater than the cationic diffusivity;

The cation transfer constant of the solid ion-conducting polymer material is less than or equal to 0.5 and greater than zero;

The solid ion-conducting polymer material includes a plurality of monomers, wherein each monomer includes an aromatic or heterocyclic ring structure located in the main chain of the monomer;

The solid ion-conducting polymer material includes heteroatoms incorporated into a ring structure or located on the main chain adjacent to the ring structure, wherein the heteroatoms are selected from the group consisting of sulfur, oxygen or nitrogen;

The heteroatoms are located on the main chain of the monomer adjacent to the ring structure of the solid ion-conducting polymer material;

The heteroatom is located on the backbone of the monomer adjacent to the ring structure of the solid ion-conducting polymer material, and the heteroatom is sulfur;

The solid ion-conducting polymer material is pi-conjugated;

The solid ion-conducting polymer material includes a plurality of monomers, each monomer having a molecular weight greater than 100 grams/mole;

The solid ion-conducting polymer material is hydrophilic;

The ionic conductivity of the solid ion-conducting polymer material is isotropic;

The solid ion-conducting polymer material is non-flammable;

The Young's modulus of the solid ion-conducting polymer material is at least 3.0 MPa;

A solid ionically conductive polymer material becomes ionically conductive after being doped by an electron acceptor in the presence of an ionic compound that contains both cationic and anionic diffusing ions or can be converted to cationic and anionic diffusing ions through oxidation by the electron acceptor;

The solid ion-conducting polymer material is formed from the reaction product of a base polymer, an electron acceptor and an ionic compound, and the base polymer may be a conjugated polymer, PPS or liquid crystal polymer;

The air electrode further comprises a second electrochemically active material, which active material may comprise a metal oxide, which may be manganese dioxide;

The first electrochemically active material includes zinc;

The first electrochemically active material comprises zinc, aluminum, calcium, magnesium, potassium, sodium or lithium;

The air electrode further comprises a second electrochemically active material, the second electrochemically active material being mixed with the electrically conductive material and the solid ion-conducting polymer material;

The ionically conductive, dielectric, non-electrochemically active material includes both an aqueous electrolyte and a nonwoven separator disposed adjacent to the air electrode;

The electrically conductive material includes carbon;

The battery is non-aqueous and ionically conductive, and the dielectric non-electrochemically active material includes a solid ionically conductive polymer material;

The ionically conductive, dielectric, non-electrochemically active material includes both an aqueous electrolyte and a nonwoven separator disposed adjacent to the air electrode;

The electrically conductive material is mixed with a solid ion-conducting polymer material, and the air electrode is thermoplastic;

The oxygen gas source is an air source, the air source includes a first concentration of oxygen, carbon dioxide and water vapor gas, and the battery further includes an air differentiation system fluidly interposed between the air electrode and the air source, the air differentiation system comprising: Supplying a second concentration of oxygen, carbon dioxide and water vapor gases to the air electrode, the air discrimination system affects the oxygen concentration reaching the air electrode when the battery is under load, and the second concentration of oxygen is equal to the first concentration of oxygen. higher, the air discrimination system affects the concentration of carbon dioxide, the second concentration of carbon dioxide is lower than the first concentration of carbon dioxide, the air discrimination system affects the concentration of water, the second concentration of water is lower than the first concentration of water Low, the air discrimination system includes a solid ion-conducting polymer material, or the air source is atmospheric air, and the battery is disposed in a seal with an air supply port, and the air supply port allows atmospheric air to flow to the air electrode.

An aspect and purpose of a battery is the ion mobility provided by solid ion-conducting polymer materials, specifically:

The ionic conductivity of the solid ion-conducting polymer material is greater than 1.0×10 ^-5 S/cm at room temperature;

The solid ion-conducting polymer material contains a single cationic diffusing ion, and the diffusion rate of the cationic diffusing ion is greater than 1.0×10 ^-12 m ² /s at room temperature;

The solid ion-conducting polymer material contains a single anionic diffusing ion, and the diffusion rate of the anionic diffusing ion is greater than 1.0×10 ^-12 m ² /s at room temperature;

At least one of the cationic diffusing ions of the solid ion-conducting polymer material has a diffusion rate greater than 1.0×10 ^-12 m ² /s;

At least one of the anionic diffusing ions of the solid ion-conducting polymer material has a diffusion rate greater than 1.0×10 ^-12 m ² /s;

one of the at least one anionic diffusing ion and the at least one cationic diffusing ion of the solid ion-conducting polymer material has a diffusion rate greater than 1.0×10 ^-12 m ² /s;

The solid ion-conducting polymer material has an ionic conductivity greater than 1×10 ^-4 S/cm at room temperature;

The solid ion-conducting polymer material has an ionic conductivity greater than 1×10 ^-3 S/cm at 80°C;

The solid ion-conducting polymer material has an ionic conductivity greater than 1×10 ^-5 S/cm at -40°C;

Cationic diffusing ions include lithium, and the diffusion rates of lithium ions and hydroxide ions are both greater than 1.0×10 ^-13 m ² /s at room temperature.

In one aspect, the battery may consist of one or more of the following characteristics:

The electrically conductive material comprises 10 to 30% by weight of the air electrode;

The solid ion-conducting polymer material comprises 5 to 50 weight percent of the air electrode;

The second electrochemically active material comprises 10 to 70% by weight of the air electrode;

The air cathode is composed of carbon, potassium permanganate, manganese dioxide, cobalt tetrapyrazinoporphyrazine derivative, perovskites, titanium doped manganese dioxide, cobalt oxide, graphene, Ketjen black, doped Ketjen black, carbon nanotubes, carbon fiber, an oxygen reduction catalyst that may be selected from cobalt manganese oxide, electrically conductive polymers and essentially conductive polymers and combinations thereof;

The air electrode includes manganese dioxide, and the manganese dioxide includes β-Mn0 ₂ (pyrolusite), ramsdelite, γ-Mn0 ₂ , ε-Mn0 ₂ , λ-Mn0 ₂ , EMD, CMD, and combinations thereof. is selected from the group.

The electrically conductive material includes carbon, and the ratio of the weight of manganese dioxide to the weight of carbon is greater than 2:1;

The first electrochemically active material includes zinc, and the ratio of the weight of zinc to the weight of manganese dioxide is greater than 1:1;

The ratio of the weight of the ion-conducting polymer material to the weight of manganese dioxide in the air electrode is greater than 1:1;

The metal-air battery further includes a metal can that acts as a positive current collector, and the air electrode is electrically connected to the can;

The can is cylindrical, and the air cathode is annular;

Cans are size AA (LR6);

The oxygen gas permeability of solid ion-conducting polymer materials is greater than the water permeability;

AA-sized cells containing air electrodes containing solid ion-conducting polymer materials exhibited capacities greater than 3 Ah capacity during the following discharges: continuous galvanostatic discharge at currents between 150 mA and 300 mA with 0.8 V voltage cutoff; Intermittent discharge at currents between 150 and 300 mA applied for 1 hour, followed by a 1 hour rest period (0.8 V voltage cut); Continuous galvanostatic discharge from 50mA to 1.0V voltage cut-off; Intermittent discharge at 50 mA applied for 1 hour, followed by a rest period of 1 hour (1.0 voltage cut); Continuous constant resistive discharge from 3.9 ohms to 0.8V cutoff; Intermittent constant resistive discharge when a 3.9 ohm resistance is applied for 1 hour, followed by a 1 hour rest period (0.8 V voltage cut); Continuous constant resistive discharge from 42 ohms to 1.0 voltage cutoff; and intermittent constant resistive discharge when a 42 ohm resistance is applied for 15 seconds, followed by a rest period of 45 seconds (1.0 V voltage cut).

In one aspect, a method of manufacturing an air electrode may include one or more of the following steps:

mixing the polymer with an ionic compound and an electron acceptor to produce a first mixture;

heating the first mixture to form the first mixture into a solid ionically conductive polymer material;

Mixing a solid ionically conductive polymer material with an electrically conductive material to produce a second mixture that reacts to reduce oxygen and ionically conduction hydroxyl ions.

In one aspect, a method of manufacturing an air electrode may further include one or more of the following steps in combination with the previous aspect:

In the second mixture mixing step, a co-depolarizing agent is added to the second mixture;

The co-depolarizing agent is manganese dioxide.

In the first mixing step, a co-depolarizing agent is added to the first mixture.

Electrically conductive materials include carbon.

A forming step is used in which the second mixture is formed with an air cathode.

In the forming step, pressure is applied to the second mixture to thermoform the second mixture into an air cathode, the air cathode is formed into a film, or the air cathode is formed into an annular shape;

The base polymer is PPS, PEEK, LCP, PPy or a combination thereof;

The dopants are selected from DDQ, TCNE, chloranyl, SO3, ozone, transition metal oxides, MnO2, oxygen and air;

An ionic compound is a salt, hydroxide, oxide or other substance that contains hydroxide ions or can be converted to a hydroxide;

Ionic compounds include LiOH, NaOH, KOH, Li20 or LiNO3;

In the heating step, the first mixture is heated to a temperature of 250 to 450 °C;

In the heating step, pressure is applied to the first mixture while the first mixture is heated, and the pressure may be 300 to 500 psi;

In the second mixing step, the manganese dioxide is sealed by a solid ion-conducting polymer material;

In the forming step, the air electrode is extruded;

In the second mixture mixing step, catalyst is added to the mixture;

In the second mixture mixing step, a hydrophobic compound is added to the mixture;

In the second mixture mixing step, a carbon dioxide adsorption compound is added to the mixture;

The positioning step is used to position the air cathode within the can and adjacent the interior surface of the can, wherein the air cathode can be shaped into an annulus, and the second annular-shaped cathode portion is adjacent to both the interior surface of the can and the air cathode. and the second cathode portion may or may not include a solid ion-conducting polymer material.

These and other features, advantages and objects will be better understood and appreciated by those skilled in the art by reference to the following detailed description, claims and accompanying drawings.

1 is a discharge curve showing cell performance using four different electrically conductive carbons.
Figure 2a is a cross-sectional view of a tool for manufacturing cathode sections.
Figure 2b is a cross-sectional illustration of air cathode annular sections formed by a tool.
Figure 3 is a cross-sectional view of an electrochemical battery cell.
Figure 4 shows discharge curves of the cell and comparison cells under continuous 150 mA discharge.
FIG. 5 is a discharge curve described in Example 7 showing the intermittent discharge voltage of the cell of Example 7 and comparative commercial cells as a function of test time.
6 is a discharge curve described in Example 8 showing intermittent discharge as a function of test time.
Figure 7 is a volume normalization curve described in Example 9, showing a comparison of volume per volume capacity ratio profiles for various techniques.
Figure 8 is a representative cross-sectional view of an aspect of the invention showing a thin film battery.

This patent application claims priority from U.S. Provisional Application No. 62/169,812, filed June 2, 2015; It is a partial continuation of U.S. Patent Application No. 15/148,085 filed on May 6, 2016, and said Patent Application No. 15/148,085 is (a) U.S. Provisional Application No. 62/158,841 filed on May 8, 2015. Claiming priority to (i) U.S. Provisional Application No. 61/911,049, filed on December 3, 2013, and U.S. Patent Application No. 14/559,430, filed on December 3, 2014; and (ii) claims priority to U.S. Provisional Patent Application No. 61/622,705, filed April 11, 2012, and is a partial continuation of U.S. Provisional Patent Application No. 13/861,170, filed April 11, 2013; The disclosures are incorporated herein by reference in their entirety.

The following description of terms is provided to better detail the description of the aspects, embodiments and purposes to be described in this section. Unless otherwise explained or defined, all technical and scientific terms used in this specification have the same meaning as commonly understood by a person skilled in the art to which this disclosure pertains. To facilitate review of various embodiments of the present disclosure, the following explanations of specific terms are provided:

A depolarizing agent is synonymous with an electrochemically active substance, i.e. a substance that changes its oxidation state or participates in the formation or destruction of chemical bonds in the electrochemical reaction and charge-transfer stage of the electrochemically active substance. When the electrode has more than one electroactive material, these can be referred to as co-polarizers.

Thermoplasticity is the property of a resinous material or polymer to become flexible or moldable above or at a certain temperature, often near its melting point, and to solidify upon cooling.

Solid electrolytes include non-solvent polymers and ceramic compounds (crystalline and glassy).

A “solid” is characterized by the ability to maintain its shape over an infinitely long period of time, and is distinct from and different from liquid substances. The atomic structure of solids may be crystalline or amorphous. Solids can be mixed or incorporated into compositional structures.

For the purposes of this application and its claims, a solid ionically conductive polymer material requires that the material be ionically conductive through a solid and not through any solvent, gel or liquid phase, unless otherwise stated. For the purposes of this application and its claims, gelled (or wet) polymers and other materials that rely on liquids for ionic conductivity are referred to as solid electrolytes (solid ionic conductive polymers) in that they rely on a liquid phase for ionic conductivity. It is defined as something that is not a substance.

Polymers are typically organic and consist of carbon-based polymers, each having one or more types of repeating units or monomers. Polymers are light, soft, usually non-conductive, and melt at relatively low temperatures. Polymers can be manufactured into products through injection, blowing and other molding processes, extrusion, pressing, stamping, three-dimensional printing, machining and other plastics processes. Polymers typically have a glassy state at temperatures below the glass transition temperature Tg. This glass temperature is a function of the flexibility of the chain and occurs when there is sufficient vibrational (thermal) energy in the system to create sufficient free-volume to allow the arrays of segments of the polymer polymer to move together as a unit. However, in the free state of the polymer, there is no segmental movement of the polymer.

Polymers are distinct from ceramics, which are defined as inorganic non-metallic materials; It is generally a compound composed of metals covalently bonded to oxygen, nitrogen, or carbon, and is brittle, rigid, and non-conductive.

The glass transition that occurs in some polymers is an intermediate temperature between the supercooled liquid state and the glassy state when the polymer material is cooled. Thermodynamic measurements of the glass transition are performed by measuring the physical properties of the polymer, such as volume, enthalpy or entropy and other derivative properties as a function of temperature. The glass transition temperature is observed on the plot as a break in the selected property (volume of enthalpy) at the transition temperature or from a change in the slope (heat capacity or coefficient of thermal expansion). When cooling a polymer from above Tg to below Tg, polymer molecular mobility slows until the polymer reaches a glassy state.

Because polymers can contain both amorphous and crystalline states, polymer crystallinity is the amount of these crystalline states relative to the amount of polymer, expressed as a percentage. The percentage of crystallinity can be calculated through x-ray diffraction of the polymer by analysis of the relative areas of amorphous and crystalline states.

Polymer films are generally described as thin sections of polymer, but should be understood as being less than 300 micrometers thick.

It is important to note that ionic conductivity is different from electrical conductivity. Ionic conductivity depends on the ionic diffusion rate, and the properties are related by the Nernst-Einstein equation. Ionic conductivity and ionic diffusion rate are both measures of ionic mobility. Ions can move within a material if the diffusion rate in the material is positive (greater than zero) or contributes to positive conductivity. All these ion mobility measurements are made at room temperature (approximately 21°C) unless otherwise specified. Because ion mobility is affected by temperature, it can be difficult to detect at low temperatures. Instrument detection limits can be a factor in determining small mobility quantities. Mobility can be understood as the ionic diffusion rate of at least 1×10 ^-14 m ² /s and preferably 1×10 ^-12 m ² /s, all of which transport ions can move within the material.

Solid polymer ionically conductive materials are solids that contain polymers and conduct ions as further described.

One aspect includes a method of synthesizing a solid ion-conducting polymer material from at least three separate components: a polymer, a dopant, and an ionic compound. The components and synthesis method are selected for the specific application of the material. The selection of polymers, dopants and ionic compounds can also vary based on the desired performance of the material. For example, desired components and synthesis methods may be determined by optimization of desired physical properties (e.g., ionic conductivity).

synthesis:

Synthetic methods may also vary depending on the specific components and desired form of the final material (e.g., film, particle, etc.). However, this method initially involves mixing at least two components, adding a third component in an optional second mixing step, and heating the components/reactants to synthesize the solid ion-conducting polymer material. It includes the basic steps of heating. In one aspect of the invention, the final mixture can optionally be formed into a film of desired size. If the dopant is not present in the mixture produced in the first step, it can be subsequently added to the mixture while heat and, optionally, pressure (positive pressure or vacuum) are applied. All three components can be provided, mixed and heated to complete the synthesis of the solid ion-conducting polymer material in a single step. However, this heating step may occur in a separate step from any mixing step, or may be completed while mixing is taking place. The heating step can be performed regardless of the form of the mixture (e.g., film, particle, etc.). In one aspect of the synthesis method, all three components are mixed and then extruded into a film. The film is heated to complete the synthesis.

When the solid ion-conducting polymer material is synthesized, a color change occurs, and this color change can be visually observed because the reactant color is relatively light and the solid ion-conducting polymer material is relatively dark or black. It is believed that this color change occurs when the charge transfer complexes are formed and can occur gradually or rapidly depending on the synthesis method.

One aspect of the synthesis method is to mix the base polymer, ionic compound and dopant together and heat the mixture in a second step. Since the dopant may be in a gaseous state, the heating step may be performed in the presence of the dopant. The mixing step can be performed in an extruder, blender, mill or other equipment typical of plastics processing. The heating step may last several hours (e.g., 24 hours), and the color change is a clear indication that the synthesis is complete or partially complete.

In one aspect of the synthesis method, the base polymer and ionic compound may first be mixed. The dopant is then mixed with the polymer-ion compound mixture and heated. Heating may be applied to the mixture during or subsequent to the second mixing step.

In another aspect of the synthesis method, the base polymer and dopant are first mixed and then heated. This heating step may be applied after or during mixing and produces a color change indicative of the formation of charge transfer complexes and the reaction between the dopant and the base polymer. The ionic compound is then mixed into the reacted polymer dopant material to complete the formation of the solid ion-conducting polymer material.

Typical methods of adding dopants are known to those skilled in the art and may include vapor doping of films containing base polymers and ionic compounds and other doping methods known to those skilled in the art. Upon doping, the solid polymer material becomes ionic, and it is believed that doping acts to activate the ionic components of the solid polymer material, causing them to diffuse ions.

Other non-reactive components may be added to the mixtures described above during the initial mixing steps, secondary mixing steps, or mixing steps following heating. These other components include depolarizers, or electrochemically active materials such as anode or cathode active materials, electrically conductive materials such as carbons, binders or extrusion aids (e.g. ethylene propylene diene monomer "EPDM"). These include, but are not limited to, rheological agents, catalysts, and other components useful in achieving the desired physical properties of the mixture.

Polymers useful as reactants in the synthesis of solid ion-conducting polymer materials are electron donors or polymers that can be oxidized by electron acceptors. Semi-crystalline polymers with crystallinity indices greater than 30% and greater than 50% are suitable reactive polymers. Fully crystalline polymeric materials, such as liquid crystal polymers (“LCPs”), are also useful as reactive polymers. LCPs are fully crystalline and therefore their crystallinity index is defined herein as 100%. Undoped conjugated polymers and polymers such as polyphenylene sulfide (“PPS”) are also suitable polymer reactants.

Polymers are generally not electrically conductive. For example, pure PPS has an electrical conductivity of 10 ^-20 Scm ^-1 . Non-electrically conducting polymers are suitable reactive polymers.

In one aspect, polymers useful as reactants can have aromatic or heterocyclic components in the main chain of each repeating monomer group, and heteroatoms incorporated into the heterocycle or located along the main chain within positions adjacent to the aromatic ring. The heteroatom may be located directly on the main chain or may be bonded to a carbon atom located directly on the main chain. In both cases where the heteroatom is located in the main chain or is bonded to a carbon atom located in the main chain, the main chain atom is located on the main chain adjacent to the aromatic ring. Non-limiting examples of polymers used in this aspect of the invention include PPS, poly(p-phenylene oxide) (“PPO”), LCPs, polyether ether ketone (“PEEK”), polyphthalamide (“PPA”) "), polypyrrole, polyaniline, and polysulfone. Co-polymers containing monomers of the listed polymers and mixtures of these polymers can also be used. For example, co-polymers of p-hydroxybenzoic acid may be suitable liquid crystal polymer base polymers.

Table 2 details non-limiting examples of reactive polymers useful in the synthesis of solid ion-conducting polymer materials, along with monomer structure and some physical property information, which explains how the polymers influence the physical properties. It should also be considered non-limiting as it can take on a number of possible forms.

polymer monomer structure melting point
(C) MW PPS polyphenylene sulfide 285 109 PPO poly(p-phenylene oxide) 262 92 PPK polyether ether ketone 335 288 PPA polyphthalamide 312 polypyrrole polyaniline poly-phenylamine [C ₆ H ₄ NH] _n 385 442 polysulfone 240 Xydar(LCP) Vectran poly-paraphenylene terephthalamide [-CO-C ₆ H ₄ -CO-NH-C ₆ H ₄ -NH-]n Polyvinylidene fluoride (PVDF) 177℃ Polyacrylonitrile (PAN) 300℃ Polytetrafluoro-ethylene (PTFE) 327 Polyethylene (PE) 115-135

Dopants useful as reactants in the synthesis of solid ion-conducting polymer materials are electron acceptors or oxidizing agents. Dopants are believed to act to release ions for ion transport and mobility, and to create charge transfer complex-like sites, i.e. sites within the polymer, to allow ionic conduction. Non-limiting examples of useful dopants include 2,3-dicyano-5,6-dichlorodicyanoquinone (C 8 Cl ₂ N ₂ O ₂ ), also known as “DDQ” and tetrachloro-dicyanoquinone (C ₈ Cl 2 N 2 O 2 ), also known as “DDQ”. Quinones such as 1,4-benzoquinone (C ₆ Cl ₄ O ₂ ), tetracyanoethylene (C ₆ N ₄ ), also known as TCNE, sulfur trioxide (“SO ₃ “), ozone (trioxygen or O ₃ ), oxygen (O ₂ , including air), transition metal oxides including manganese dioxide (MnO ₂ ), or any suitable electron acceptor, etc., and any combinations thereof. Dopants that are temperature stable at the temperatures of the synthesis heating step are useful, and quinones and other dopants that are all temperature stable and quinones that are strong oxidizers are very useful. Table 3 provides a non-limiting list of dopants along with their chemical structures.

dopant chemical formula structure 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) C ₆ Cl ₂ (CN) ₂ O ₂ Tetrachloro-1,4-benzoquinone (chloranil) C ₆ Cl ₄ O ₂ Tetracyanoethylene (TCNE) C ₆ N ₄ sulfur trioxide SO ₃ ozone O ₃ Oxygen O ₂ transition metal oxides M _x O _y (M=transition metal, x and y are 1 or more)

Ionic compounds useful as reactants in the synthesis of solid ion-conducting polymer materials are compounds that release the desired ions during the synthesis of the solid ion-conducting polymer material. Ionic compounds are distinct from dopants in that they require both an ionic compound and a dopant. Non-limiting examples include Li ₂ O, LiOH, NaOH, KOH, LiNO ₃ , Na ₂ 0, MgO, CaCl ₂ , MgCl ₂ , AlCl ₃ , LiTFSI (lithium bis-trifluoromethanesulfonimide), LiFSI ( lithium bis(fluorosulfonyl)imide), lithium bis(oxalato)borate (LiB(C ₂ 0 ₄ ) ₂ “LiBOB”) and other lithium salts and combinations thereof. Hydrated forms (eg, monohydrides) of these compounds can be used to simplify handling of the compounds. Inorganic oxides, chlorides and hydroxides are suitable ionic compounds in that they dissociate during synthesis to produce at least one anionic and cationic diffusing ion. Any such ionic compound that dissociates to produce at least one anionic and cationic diffusing ion would be similarly suitable. Multiple ionic compounds may also be useful in that the result of multiple anionic and cationic diffusing ions may be desirable. The specific ionic compound involved in the synthesis depends on the required availability of the material. For example, in applications where it is desirable to have a hydroxide anion, lithium hydroxide or an oxide convertible to a hydroxide ion would be suitable. This is because it may be the hydroxide-containing compounds that release diffusive anions during synthesis. A non-limiting group of these hydroxide ionic compounds include metals. Hydroxide ionic compounds may include alkali metals, alkaline earth metals, transition metals, and post-transition metals in a form capable of producing the desired cationic and anionic diffusing species are suitable as synthetic reactive ionic compounds.

The purity of materials is potentially important to prevent unintended side reactions and maximize the effectiveness of synthetic reactions to produce highly conductive materials. In general, substantially pure reactants with high purities of dopant, base polymer and ionic compound are useful, purities exceeding 98% are more useful, and even higher purities such as LiOH: 99.6%, DDQ: > 98% and Chloranil: > 99% are also useful.

To further describe the utility of solid ion-conducting polymer materials and the versatility of the above-described methods of synthesizing solid ion-conducting polymer materials, several classes of solid ion-conducting polymer materials are useful in a number of electrochemical applications and distinguished by their applications. This is described:

Example 1

The PPS polymer was mixed with the ionic compound LiOH monohydrate at a ratio of 67% to 33% (by weight), respectively, and mixed using jet milling. This undoped mixture can be extruded into a film or other form prior to doping. A portion is extruded into the film to produce an undoped film (of PPS and LiOH). The DDQ dopant was added to the final mixture through steam doping at a temperature of 250 to 325°C for 30 minutes under appropriate pressure (500-1000PSI) to synthesize a solid ion-conducting polymer material (PPS/LiOH/DDQ). In one aspect, the solid ion-conducting polymer material PPS/LiOH/DDQ is synthesized in particle form by first mixing the DDQ dopant and the base polymer PPS monomer. The ionic compound LiOH is added and the three-component mixture is heated to 250 to 325° C. to produce particle shapes.

Electronic conductivity was measured using the electrostatic method between blocking electrodes and determined to be approximately 6.5×10 ^-9 S/cm (less than 1×10 ^-8 S/cm).

Ion diffusion measurements were performed on compression molded particle forms of PPS/LiOH/DDQ material using basic NMR techniques. Specifically, the diffusion rates of lithium and hydroxide ions were evaluated by the pulsed gradient spin echo (“PGSE”) lithium NMR method. PGSE-NMR measurements were performed using a Varian-S Direct Drive 300 (7.1 T) spectrometer. The solid polymer ion-conducting material had a diffusion rate of Li ⁺ of 5.7 × 10 ^-11 m ² /s at room temperature, and the diffusion rate of OH ^- ions was 4.11 × 10 ^-11 m ² /s at room temperature. These diffusion rate values can be used to calculate anion and cation transfer constants. Although related, the anion transfer constant is more relevant given that the diffusion rate of hydroxide is important in alkaline batteries.

After synthesis, a 20-micron thick film of solid ion-conducting polymer material was tested for permeability to air components (i.e., oxygen, water, and carbon dioxide) at room temperature. The permeability of a solid ion-conducting polymeric material film and an undoped film (20 microns thick) was compared with Zitex G-104 film from Saint-Gobain (100 microns thick), and the results are expressed in units of mole gas/cm ² -sec. The transmittance results are detailed in Table 4 detailing them.

gas Non-doped film Film in Example 1 Zitex Oxygen (O ₂ ) 2.1×10 ^-9 1× ^10-8 2.1×10 ^-6 water (H ₂ O) 0 1.3×10 ^-8 1.5×10 ^-8 Carbon dioxide (CO ₂ ) 0 1.4×10 ^-8 ×10 ^-10

Doping causes significant changes in the transmittance properties of polymer films. The synthesized solid polymer films exhibit some gas discriminating properties, and oxygen permeability is significant, which can be contrasted with the relatively low carbon dioxide permeability. Undoped polymer films are impermeable to water and carbon dioxide. In one aspect, a combination of doped and undoped solid polymer films can provide water and carbon dioxide impermeability in a gas differential system.

Zinc-Air Battery:

Solid ion-conducting polymer materials that can be manufactured using mass production processes are applicable to metal-air batteries. One aspect is a metal-air cell comprising an air cathode and an air cathode based on a solid ion-conducting polymer material.

The air cathode simplifies the prior art metal-air cathode by using a single layer comprising electrically conductive carbon powder mixed with a solid ion-conducting polymer material. Electrically conductive carbon may be in the form of graphite, carbon black, graphenes, electrically conductive polymers, or mixtures thereof.

In one aspect, additional catalyst is added to the air electrode. Although the combination of solid ion-conducting polymer materials and electrically conductive carbon powders provides sufficient catalytic rate performance, potassium permanganate, manganese dioxide, cobalt tetrapyrazinoporphyrazine derivatives, perovskites and other compounds are effective in reducing the oxidation of peroxides. It is useful for further catalyzing chemical decomposition and can therefore be added selectively.

Example 2

The air electrode is prepared by mixing the solid ion-conducting polymer material prepared in Example 1 with electrically conductive carbon powder in the desired ratio and compression-molding onto an electrically conductive (e.g., metal) current collector electrically connected to the positive terminal of the cell. do.

Air electrodes are manufactured by blending a solid electrolyte polymer material with various carbons: TIMCAL SUPER C45 conductive carbon black (C45), Timcal SFG6 (synthetic graphite), Ashbury's A5303 carbon black and Ashbury's natural impression graphite Nano99 (N99). It has been done. The carbon content varied from 15 to 25% by weight. The cathodes were drilled to fit the 2032 coin cell. Zinc foil was used as anode. The nonwoven separator was soaked in 40% KOH aqueous solution. Two holes were drilled in the top of the coin facing the cathode. Cells were discharged at room temperature with a constant current of 0.5 mA using an MTI coin cell tester.

Cathode parameters and test results are summarized in Table 5. Discharge curves are shown in Figure 1. Cells with air cathodes typically exhibited the discharge behavior of Zn-air cells without any conventional catalysts (e.g. based on transition metals) added to the mixture.

Cathode # carbon C% T(mil) Wt(mg) g/cc OCV(V) mAh One C45 15% 23.3 102.7 0.553 1.2667 5.628 2 N99 25% 25.3 137.8 0.757 1.3343 4.742 3 A5303 20% 21.5 116.8 0.755 1.3405 7.864 4 SFG6 25% 29.2 166.3 0.791 1.3185 6.539

Air-Assisted Zinc-Mn02 Battery:

In air-assisted zinc-manganese dioxide batteries, the second depolarizer or electrochemically active cathode material includes, but is not limited to, EMD and CMD, β-Mn0 ₂ (pyrroleucite), ramsdelite, γ-Mn0 ₂ , ε-MnO ₂ , λ-MnO ₂ and other MnO ₂ phases, or mixtures thereof. Although this example is limited to an air-assisted zinc-MnO ₂ system, other depolarizer materials can be added to other metal-air systems. These secondary depolarizers are added in the range of 30 to 70% by weight.

Electrically conductive carbons, such as those listed in Example 2, are useful, as are other electrically conductive carbons, such as Ketjenblack EC-600 JD, and other conductive additives typical and known in the battery field. These electrically conductive carbons are added in the range of 10 to 60% by weight.

The solid ionic polymer material can be prepared independently or during the fabrication of the air cathode. In one aspect, the reacted polymer and ionic compound are mixed with air and then heated to produce a solid ion-conducting polymer material. In another aspect, the reacted polymer and ionic compound are mixed with EMD or other depolarizing agent and then heated to produce a solid ion-conducting polymer material. During heating, the mixture undergoes a color change indicating reaction and transition to an ionically conductive material. After the heating step, the KOH solution and the selected electrically conductive material are added in a second mixing step. EMD can be included in the second mixing step if it has not already been added. If EMD is included in the first mixing step, additional EMD can optionally be added for open circuit voltage (“OCV”) maintenance, as the heating step may affect the air electrode OCV. The material exits the heating stage in a friable state and is easily mixed and granulated in the second stage, thus not requiring any re-grinding. The second mixing step can produce granules that are environmentally stable and ready to be molded into the desired air cathode shape.

In one aspect, the cathode uses the tool 10 shown in FIG. 2A , which includes a cylindrical outer tube 15, a center pin 20, and longitudinal bushings 25, 26 arranged to create an annular interior space. It can be manufactured using The desired amount of cathode material powder 30 is loaded into tool 10 into which a center pin 20 is inserted. The upper end bushing 26 is inserted and the tool is placed under the press.

Referring to Figure 2b, external pressure is applied (shown by arrow) to drive the end bushings to a predetermined depth. The final hollow cathode ring 35 can then be transferred into the can.

3, a standard ANSI sized cylindrical can 100 is shown, which is useful for constructing an air-assisted battery.

In this aspect, three cathode rings 121, 122, 123 are used to construct the cell. After all cathode sections have been moved into the can, additional pressure can be applied to press the cathode against the can wall, ensuring intimate contact between the air cathode 120 and can 100.

The separator assembly 130 is placed within the can 100 after the cathode is in place and positioned adjacent the air cathode 120. The separator assembly is typical for alkaline cells. The separator material may be selected from separators traditionally used in industry, for example non-woven materials. A measured amount of a typical electrolyte used in alkaline cells, such as a 40% KOH solution, can be added to the separator to wet it and enable ionic conductivity. After the electrolyte is absorbed, the interior volume is filled with a measured amount of zinc material to form the anode 140. The conductive nail 150, negative terminal 160, and seal assembly (not shown) are then placed within the cell and secured in place.

In another aspect the cathode may be manufactured by loading the desired amount of cathode material powder directly into the bottom of a can and then driving a central pin through the cathode material to form the cathode. This cathode fabrication method is typical of commercial alkaline battery cathode fabrication and is called impact forming due to the impact forces used to form the cathode. To maintain the can's original appearance, the can is first placed into a reinforced cylinder before a central pin impact creates an annularly shaped cathode.

The anode material may be in the form of a slurry containing alloy zinc powder, KOH, gelling agents and stabilizing additives such as zinc oxide, indium hydroxide, organic surfactants, etc. The anode slurry is prepared and handled in a manner typical of commercial alkaline batteries.

Except for the cathode material powder preparation, all materials and processes may be typical for the alkaline industry and familiar to those skilled in the art. Accordingly, many existing processes and equipment can be utilized to fabricate these batteries.

The solid ionically conductive polymer material retains the thermoplastic physical properties of its base polymer. For example, it can be thermoformed, extruded, or otherwise molded into many shapes, such as cobwebs, rings, powders, meshes, convolutions, coatings, films, and other useful shapes. . Because the cathode material is sealed by a solid ion-conducting polymer material, the air cathode is itself thermoplastic because it can be molded while maintaining this seal. Ion-conducting polymer materials of this nature are particularly useful for metal-air or air-assisted batteries, in that air electrodes can now be manufactured from a single layer of multiple shapes.

Like most polymers, solid ionically conductive polymer materials can be mixed with substances to change their physical properties. In the case of metal-air or air-auxiliary batteries, differentiated inputs of oxygen, water and carbon dioxide are desirable. Hydrophobicity can be engineered into the metal-air or air-assisted battery air electrode by the addition of hydrophobic materials such as Teflon®, liquid crystal polymers or other known water barriers. Carbon dioxide can be made impermeable using suitable films, engineered, or adsorbed by suitable compounds such as zeolites with naturally occurring adsorbent moieties.

These carbon dioxide zeolites can be mixed with a solid ion-conducting polymer material or placed within a membrane between the cathode and any air access orifice to create a gas discrimination system that selectively provides carbon dioxide and water permeability. while preventing oxygen from entering the cell at the rate necessary to enable the desired electrochemical discharge rates.

Air is supplied to the cell shown in Figure 3 through air holes (not shown) located in the seal assembly and/or can walls. A gas differentiation system can be used to protect the cell from leakage, such a membrane can be placed in the middle of the air electrode and any air entry inlet, such as an air hole, to regulate atmospheric gas permeability and prevent water from escaping the cell. can do. This gas discrimination system may include a Teflon film, a solid ion-conducting polymer material, other gas discrimination membranes such as Zitex®, or a hydrophobic protective membrane such as the undoped material detailed in Example 1. Zeolites and other adsorption additives may also be included by incorporation into a film or by placing them within the gas differentiation system in another manner.

In one aspect, air cathodes can be used in batteries with mixed cathode structures. This hybrid structure uses the air cathode described in combination with a typical alkaline cathode structure. For example, in the configuration described in relation to Figure 3, three cathode rings 121-123 are shown. In this aspect, at least one of the rings includes manganese dioxide, conductive carbon, KOH electrolyte, and other additives typical of alkaline battery cathodes, but does not include any solid ion-conducting polymer material. It shall not contain solid ion-conducting polymeric materials. Additionally, at least one ring will comprise a solid ionically conductive polymer material and at least an electrically conductive material such as carbon. These rings comprising solid ion-conducting polymer materials may also further comprise manganese dioxide or other co-depolarizers, catalysts and other mentioned additives. This aspect of construction allows for high release rates due to the lowered relative impedance of the ring without the solid ion-conducting polymer material.

However, this structure also allows the ring to be recharged without a solid ion-conducting polymer material, due to its ability to conduct hydroxide ions through the aqueous electrolyte. Accordingly, this heterogeneous configuration further demonstrates the utility of solid ion-conducting polymer materials and their ability to enhance the performance of typical systems when used in such systems.

Accordingly, solid ion-conducting polymers can be incorporated into air electrodes having desired shapes, surface areas, porosity, and gas distinguishing properties.

Example 3

The ground poly(phenylene sulfide) polymer and lithium hydroxide monohydrate were added together at a ratio of 67 to 33% by weight, respectively, and mixed using jet milling. The final ionic compound-polymer mixture, manganese dioxide powder (EMD from Erachem) and C45 carbon black were added together in proportions of 30%, 50% and 20% respectively and mixed thoroughly using a V-blender.

The V-blended mixture was placed in a heating vessel and heated to the desired heat treatment temperature (305 to 345° C., or greater than 300° C., and 250 to 450° C.) for a specified period of time (10-50 minutes). After cooling, the final material was mixed with carbon. In one aspect, the composition is 50% manganese dioxide, 20% Ketjenblack EC-600JD, and 30% polymer/LiOH mixture by weight. In another aspect, it may include 10-30% by weight carbon and 40-70% by weight manganese dioxide, with the remainder being polymers, ionic compounds and other additives.

The powder resulting in the cathode was ground again and mixed with about 6% by weight of a 40% KOH solution to create an air cathode mixture.

Example 4

The air cathode mixture of Example 3 was loaded into a tool containing a cylindrical outer tube, center pin and end bushings. The desired amount of cathode material powder is loaded into the tool with the lower bushing and center pin inserted. The upper bushing is then inserted and the tool is placed under pressure. Hydraulic pressure is applied to drive the drive end bushing to a pre-defined depth to form cathode sections molded into hollow rings (Figure 2a).

After the bushing is extracted, the cathode section can be transferred into the can. Typically three cathode sections are used to construct the cell. After the cathode sections are in place, the center pin is reinserted and pressure is applied to expand the cathode sections and secure them in place (Figure 2b).

A conventional separator assembly made of commercial non-woven separator (NKK) was inserted into the battery. Afterwards, 0.6 cc of 40% KOH solution was added. Zn anode slurry extracted from commercial alkaline cells was added into the separator. The nail and seal assembly was inserted and secured by lightly compressing the cell walls (Figure 2C).

Air access holes were drilled into the battery can to provide air access.

Example 5

The AA cell configuration described in Example 4, including the air cathode and cell design, was compared to a comparative commercial AA cell (“Coppertop®”) in Table 6 below:

Example 4 (grams) Coppertop (gram) cathode EMD 1.0 8.1 carbon 0.4 0.63 bookbinder 0.05 KOH 0.17 0.17 polymer electrolyte 0.6 anode zinc slurry 6.8 3.8

The air cathode energy density is relatively high and therefore does not need to be as thick as the cathodes of typical alkaline batteries, and the reduced volume lowers the raw material requirements of the air cathode. The larger internal void provided by the thinner cathode allows for a larger anode for metal-air batteries. The larger interfacial area between the anode and cathode also allows for a higher mass transfer area between the electrodes enabling higher discharge rates. The amount of zinc slurry can be almost double that of a commercial cell, and the corresponding zinc to EMD ratio is much greater than 1:1. That is, the anode to cathode electrochemical activity weight ratio is greater than 1 (1:1). The anode co-depolarizer EMD to carbon weight ratio is greater than 2:1 and the co-depolarator EMD to polymer electrolyte weight ratio is greater than 1:1.

Example 6

After checking the open circuit voltage and impedance, the assembled cells of Example 4 were placed into cell holders and tested using a Maccor 4600A instrument.

Figure 4 shows the discharge curves of the AA cell produced in Example 4 and the comparative Duracell Coppertop® (black) under continuous 150 mA discharge. The battery delivered 4.2Ah until the voltage cut off at 0.8V. In comparison, commercial battery capacity under the same conditions was limited to about 2.6 Ah.

Example 7

After checking the open circuit voltage and impedance, the cells assembled in Example 4 were placed into cell holders and tested using a Maccor 4600A instrument.

Each cell was subjected to intermittent discharge for 15 seconds at a 24 ohm resistive load followed by a 45 second rest. Testing continued until the cell voltage dropped to 1.0V. This discharge protocol can be considered an accelerated version of the standard remote control test because the standard test applies load for only 8 hours per day.

Referring to Figure 5, the cell of Example 4 was compared to commercially available Duracell Coppertop® and Energizer Max® cells. Under these discharge conditions, the cell in Example 4 lasted more than 20% longer than a commercial AA cell.

Example 8

After checking the open circuit voltage and impedance, the cells of Example 4 were placed into cell holders and tested using a Maccor 4600A instrument.

The cells underwent intermittent discharge for 1 hour at a 3.9 ohm resistive load followed by 1 hour of rest. Testing continued until the cell voltage dropped to 0.8V. This discharge protocol can be considered an accelerated toy test because it uses a shorter rest period compared to the standard toy test (1 hour vs. 23 hours).

Figure 6 shows discharge as a function of time. Under these discharge conditions, the cell of Example 4 lasted nearly 200% longer than a commercial cell.

AA cells also exhibited capacities greater than 3 Ah during the following discharges: continuous galvanostatic discharge at currents between 150 mA and 300 mA with a 0.8 V voltage cutoff; Intermittent discharge at currents between 150 and 300 mA applied for 1 hour, followed by a 1 hour rest period (0.8 V voltage cut); Continuous galvanostatic discharge from 50mA to 1.0V voltage cut-off; Intermittent discharge at 50 mA applied for 1 hour, followed by a rest period of 1 hour (1.0 V voltage cut); Continuous constant resistive discharge from 3.9 ohms to 0.8V cutoff; Intermittent constant resistive discharge when a 3.9 ohm resistance is applied for 1 hour, followed by a 1 hour rest period (0.8 V voltage cut); Continuous constant resistive discharge from 42 ohms to 1.0V cut-off; and intermittent constant resistive discharge when a 42 ohm resistance is applied for 15 seconds, followed by a rest period of 45 seconds (1.0 V voltage cut).

Example 9

To compare the performance of cells made according to this application to comparable competing technologies typically implemented in different form-factors, cell capacity and discharge rate were normalized by cell volume. Both the cells assembled in Example 4 and the Druacell Coppertop alkaline cells were discharged at constant currents of 150 and 250 mA. The capacity delivered during discharge was divided by the volume of a standard AA cell to produce Ah/L. Discharge current was similarly normalized by cell volume to yield A/L.

Panasonic PR2330 coin cells were discharged at 10 and 15 mA constant current. Capacity and discharge rate were normalized per cell volume as described above. Performance parameters for the Cegasa ALR40/100 cell, the smallest cell of the cylindrical design, were taken from the data sheet and normalized to cell volume. The performance of the air-assisted Eveready D cell was calculated based on the results disclosed in U.S. Patent No. 5,079,106. The performance of air-assisted Duracell AA cells was calculated based on results reported in US Patent No. 7,238,448 and US Patent No. 7,615,508. The discharge rate during intermittent discharge was converted to continuous discharge equivalent by averaging the current drawn over the reported duty cycle. For example, a 600mA load for 2 seconds followed by a 28 second pause is equivalent to a 40mA continuous discharge (600*2/30=40). Data were normalized per cell volume as described above.

Referring to Figure 8, a comparison of volumetric capacity versus velocity profiles for the cells listed above is shown. Air-assisted cells perform at discharge rates typical of alkaline cells and exhibit much larger cell capacities.

It is theorized that solid ion-conducting polymer materials improve performance by participating in electrochemical reactions (oxygen reduction), promoting oxygen reduction, and improving the hydrophobic properties of the cathode.

thin film air cathode

In one aspect of the invention, the described air cathode comprising a solid ion-conducting polymer material may take the form of a thin film structure. The solid ion-conducting polymer material allows the air cathode to include one or more film layers that can be incorporated into a can-like structure, have a flexible housing, or as a flexible thin-film battery that operates without any container or housing. make it work. Referring to Figure 7, a graphical representation of thin film battery 200 in this aspect is shown. This aspect features thin film batteries, but is not limited to the relative thickness of the battery components to be described.

The cathode 210 is shown as comprising three component layers, and the air electrode 220 has both a first surface 221 and a second surface 222 that accept oxygen from the atmosphere or other oxygen source. The air cathode is electrically connected to a cathode collector 225 that contacts the air cathode and provides electrical conductivity from the air cathode 220 to the load 226. The air cathode includes a material and an electrically conductive material such as carbon, graphite or other materials commonly used in cathodes as the conductive material.

The air cathode can receive oxygen from the gas differentiation layer 230 through the second surface 222. The gas distinguishing layer is optional and may be incorporated into the air cathode in one aspect of the invention. The gas differentiation layer receives greater partial concentrations of oxygen than are available in the battery, such as in air; When the battery benefits from lower concentrations of water and carbon dioxide than would otherwise be available in the battery; and when the battery would benefit from a barrier to moisture loss flow from the air electrode, which may be useful and desirable in environments where an air electrode would benefit. Differential transport of oxygen, water and carbon dioxide can be engineered into a gas differentiation layer by including materials that enable such differential transport and can be incorporated into the gas differentiation layer. These materials include hydrophobic materials such as Teflon, liquid crystal polymers (“LCPs”) or other known water barriers, and carbon dioxide adsorption zeolites with engineered or naturally occurring adsorption moieties. These materials can be mixed with solid ion-conducting polymer materials or other membranes to create a gas discrimination system that selectively delays and prevents carbon dioxide and moisture permeation while allowing oxygen to enter the cell and achieve desired electrochemical exit rates. This allows the air electrode to be reached at the speed necessary to make it possible.

Under load, and with oxygen being transported to the air electrode 220, the air electrode acts to electrochemically reduce the oxygen to hydroxide ions, which, along with the oxygen, are transferred from the air electrode to its constituent solid ions. There is ion conduction to the first surface 221 through the conductive polymer material. The first surface may be ionically connected to a second portion 240 of the air cathode containing an optional co-depolarizer. The second portion of the air cathode includes a solid ionically conductive polymer material, an electrically conductive material such as carbon, and a co-depolarizer such as EMD or another suitable cathode depolarizer. In one aspect, the second portion of the cathode may comprise a potassium hydroxide solution and act to transport this solution to the first surface 221 and through the cathode 210 within the aqueous metal-air cell. EMD or other co-depolarizer reacts electrochemically and, in its reduced form, can be reoxidized by peroxide ions and oxygen transported to the second part of the cathode or a combination air cathode. Although this layer or second portion is described as a separate film, in one aspect it could be integrated into the air cathode, or replaced accordingly. This layer is also ionically conductive because it contains a solid ionically conductive polymer material, is electrically conductive because it is carbon or other suitable electrically conductive material, and serves to ionically conduct hydroxide ions across the separator layer 250 to the anode. .

Separator layer 250 is comprised of a solid ionically conductive polymer material and is not electrically conductive when acting as a dielectric barrier between cathode 210 and anode 260. This separator layer may be a separate layer or may be integrated into the anode 260. As such, the separator layer 250 is ionically conductive, dielectric, and non-electrochemically active, and is inserted between the air electrode 250 of the cathode 210 or the second portion 240 when the second portion 240 is included. do. In aqueous batteries, the separator layer also acts as a fluid transport layer between the anode and cathode. The separator layer is inserted between the anode and the cathode and adjacent the cathode, whether the cathode includes an air cathode and/or a second cathode layer.

Anode 260 includes an anode current collector 265, which may be physically connected to the current collector, such as if the anode were a metal foil or metal structure, or if the anode comprised an electrochemically active material disposed within a gel-like material to generate current. It is electrically connected to the collector. In one aspect, the anode 260 may comprise a solid ionically conductive polymer material, in which case the solid ionically conductive polymer material electrically insulates the electrochemically active material and any electrically conductive material from the cathode 210. The separator layer 250 is not necessary in that it can act to do so. If the electrochemically active material is sealed by a solid ion-conducting polymer material, the anode may not require any additional environmental protection. However, such protection can be provided by enclosing the anode and battery in a pouch, can, housing, or other typical battery enclosure.

This described aspect of the invention provides design flexibility and enables high energy density flexible batteries. Battery 200 and its components may be sized for the application and may be sealed or unsealed. Because the solid ion-conducting polymer material is thermoplastic, the described components of battery 200 can be heat-sealed, co-extruded, or otherwise integrated into a single coextruded film.

Although the invention has been described in detail herein in accordance with certain preferred embodiments, many modifications and changes may be made by those skilled in the art without departing from the spirit of the invention. Accordingly, it is not intended to be limited by the details and instrumentalities described in the embodiments shown herein, but only by the scope of the appended claims. It should be understood that variations and modifications may be made to the above-described structure without departing from the concepts of the aspects described, and that such concepts are not defined in the appended claims unless the language of the appended claims explicitly states otherwise. It should be understood that it is intended to be covered by.

Claims (120)

In a metal-air battery,
an air electrode comprising an electrically conductive material and a solid ion-conducting polymer material;
a negative electrode comprising a first electrochemically active material; and
comprising an ionically conductive, dielectric, non-electrochemically active material interposed between the air electrode and the negative electrode and in contact with the air electrode,
the air electrode acts to reduce oxygen when the air electrode is exposed to an oxygen gas source and when the battery is under load,
the air electrode generates hydroxide ions when reducing oxygen, and the solid ion-conducting polymer material conducts hydroxide ions,
The first electrochemically active material is selected from the group comprising zinc, aluminum, calcium, magnesium, potassium, sodium or lithium,
Metal-air battery. According to paragraph 1,
The solid ion-conducting polymer material:
crystallinity greater than 30%; melt temperature; and at least one both cationic and anionic diffusing ion,
The ionic conductivity of the solid ion-conducting polymer material is greater than 1.0×10 ^-5 S/cm at room temperature,
At least one diffusing ion is mobile at room temperature,
Metal-air battery. According to paragraph 1,
The electronic conductivity of the solid ion-conducting polymer material is less than 1×10 ^-8 S/cm at room temperature,
Metal-air battery. According to paragraph 2,
wherein the at least one cationic diffusing ion comprises an alkali metal, an alkaline earth metal, a transition metal, or a post-transition metal.
Metal-air battery. According to paragraph 2,
wherein there is at least one mole of the cationic diffusing ion per liter of the solid ion-conducting polymer material,
Metal-air battery. According to paragraph 1,
The solid ion-conducting polymer material is formed by the reaction of a polymer, an electron acceptor, and an ionic compound,
Metal-air battery. According to paragraph 1,
wherein the solid ion-conducting polymer material is thermoplastic,
Metal-air battery. According to paragraph 2,
The anionic diffusing ion is a hydroxide ion,
Metal-air battery. According to paragraph 2,
wherein the ionic conductivity of the solid ion-conducting polymer material is isotropic,
Metal-air battery. According to paragraph 1,
The solid ion-conducting polymer material has an ionic conductivity greater than 1×10 ^-4 S/cm at room temperature,
Metal-air battery. According to paragraph 1,
The solid ion-conducting polymer material has an ionic conductivity greater than 1×10 ⁻³ S/cm at 80° C.
Metal-air battery. According to paragraph 1,
The solid ion-conducting polymer material has an ionic conductivity greater than 1×10 ^-5 S/cm at -40°C,
Metal-air battery. According to paragraph 1,
The air electrode further includes a second electrochemically active material, wherein the second electrochemically active material includes a metal oxide.
Metal-air battery. According to clause 13,
The metal oxide is manganese dioxide,
Metal-air battery. According to paragraph 1,
wherein the battery is non-aqueous, and the ion-conducting, dielectric, non-electrochemically active material comprises a solid ion-conducting polymer material.
Metal-air battery. According to paragraph 1,
The electrically conductive material includes carbon,
Metal-air battery. According to paragraph 1,
wherein the ionically conductive, dielectric, non-electrochemically active material includes both an aqueous electrolyte and a nonwoven separator disposed adjacent to the air electrode.
Metal-air battery. According to paragraph 1,
The air electrode further includes an oxygen reduction catalyst,
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