Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
  • H01M4/628—Inhibitors, e.g. gassing inhibitors, corrosion inhibitors
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B39/00—Compounds having molecular sieve and base-exchange properties, e.g. crystalline zeolites; Their preparation; After-treatment, e.g. ion-exchange or dealumination
  • C01B39/02—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof; Direct preparation thereof; Preparation thereof starting from a reaction mixture containing a crystalline zeolite of another type, or from preformed reactants; After-treatment thereof
  • C01B39/026—After-treatment
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M10/00—Secondary cells; Manufacture thereof
  • H01M10/05—Accumulators with non-aqueous electrolyte
  • H01M10/052—Li-accumulators
  • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
  • H01M4/621—Binders
  • H01M4/622—Binders being polymers
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
  • H01M2004/027—Negative electrodes
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
  • Y02E60/10—Energy storage using batteries

Definitions

• This invention generally relates to inorganic materials, e.g., trapping agents or additives for use in an electrochemical cell, such as a lithium-ion secondary battery. More specifically, this disclosure relates to the use of zeolites as inorganic trapping agents or additives located in one or more electrodes (positive or negative), in the separator, or in the electrolyte of a cell used in a lithium-ion secondary battery.
• inorganic materials e.g., trapping agents or additives for use in an electrochemical cell, such as a lithium-ion secondary battery. More specifically, this disclosure relates to the use of zeolites as inorganic trapping agents or additives located in one or more electrodes (positive or negative), in the separator, or in the electrolyte of a cell used in a lithium-ion secondary battery.
• the statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
• the main difference between a lithium-ion battery and a lithium-ion secondary battery is that the lithium- ion battery represents a battery that includes a primary cell and a lithium-ion secondary battery represents a battery that includes secondary cell.
• the term "primary cell” refers to a battery cell that is not easily or safely rechargeable, while the term “secondary cell” refers to a battery cell that may be recharged.
• a “cell” refers to the basic electrochemical unit of a battery that contains the electrodes, separator, and electrolyte.
• a “battery” refers to a collection of cell(s), e.g., one or more cells, and includes a housing, electrical connections, and possibly electronics for control and protection.
• lithium-ion (e.g., primary cell) batteries are not rechargeable, their current shelf life is about three years, after that, they are worthless. Even with such a limited lifetime, lithium batteries can offer more in the way of capacity than lithium-ion secondary batteries.
• Lithium batteries use lithium metal as the anode of the battery unlike lithium ion batteries that can use a number of other materials to form the anode.
• One key advantage of lithium-ion secondary cell batteries is that they are rechargeable several times before becoming ineffective.
• Lithium-ion secondary batteries because of the high energy density, are widely applied as the energy sources in many portable electronic devices (e.g., cell phones, laptop computers, etc.), power tools, electric vehicles, and grid energy storage.
• a lithium-ion secondary battery generally comprises one or more cells, which includes a negative electrode, a non-aqueous electrolyte, a separator, a positive electrode, and a current collector for each of the electrodes. All of these components are sealed in a case, an enclosure, a pouch, a bag, a cylindrical shell, or the like (generally called the battery’s “housing”).
• Separators usually are polyolefin membranes with micro-meter-size pores, which prevent physical contact between positive and negative electrodes, while allowing for the transport of lithium- ions back and forth between the electrodes.
• a non-aqueous electrolyte which is a solution of lithium salt, is placed between each electrode and the separator.
• the Coulombic efficiency describes the charge efficiency by which electrons are transferred within the battery.
• the discharge capacity represents the amount of charge that may be extracted from a battery.
• Lithium-ion secondary batteries may experience a degradation in capacity and/or efficiency due to prolonged exposure to moisture (e.g., water), hydrogen fluoride (HF), and dissolved transition-metal ions (TM n+ ).
• moisture e.g., water
• HF hydrogen fluoride
• TM n+ dissolved transition-metal ions
• the lifetime of a lithium-ion secondary battery can become severely limited once 20% or more of the original reversible capacity is lost or becomes irreversible.
• the ability to prolong the rechargeable capacity and overall lifetime of lithium-ion secondary batteries can decrease the cost of replacement and reduce the environmental risks for disposal and recycling.
• Figure 1A is a schematic representation of a lithium-ion secondary cell formed according to the teachings of the present disclosure in which an inorganic additive forms a portion of the positive electrode.
• Figure 1 B is a schematic representation of another lithium-ion secondary cell formed according to the teachings of the present disclosure in which an inorganic additive forms a portion of the negative electrode.
• Figure 1C is a schematic representation of yet another lithium-ion secondary cell formed according to the teachings of the present disclosure in which an inorganic additive forms a coating on the separator.
• Figure 1 D is a still another schematic representation of a lithium-ion secondary cell formed according to the teachings of the present disclosure in which an inorganic additive is dispersed within the electrolyte.
• Figure 2A is a schematic representation of a lithium-ion secondary battery formed according to the teachings of the present disclosure showing the layering of the secondary cells of Figures 1 A-1 D to form a larger mixed cell.
• Figure 2B is a schematic representation of the lithium-ion secondary battery of Figure 2A in which an inorganic additive further forms a coating on the internal wall of the housing.
• Figure 3A is a schematic representation of a lithium-ion secondary battery formed according to the teachings of the present disclosure showing the incorporaiton of the secondary cells of Figures 1 A-1 D in series.
• Figure 3B is a schematic representation of the lithium-ion secondary battery of Figure 3A in which an inorganic additive further forms a coating on the internal wall of the housing.
• Figure 4 is a scanning electon micrograph (SEM) of the surface of a coated separator prepared according to present disclosure.
• Figure 5 is a graphical representation of the normalized discharge capacity measured as a function of cycles for a cell having a conventional separator and a cell having a coated separator prepared accoding to the present disclosure.
• Figure 6 is a graphical representation of the coulombic efficiency measured as a function of cycles for a cell having a conventional separator and a cell having a coated separator prepared accoding to the present disclosure.
• the terms “about” and “substantially” are used herein with respect to measurable values and ranges due to expected variations known to those skilled in the art (e.g., limitations and variability in measurements).
• the terms “at least one” and “one or more of” an element are used interchangeably and may have the same meaning. These terms, which refer to the inclusion of a single element or a plurality of the elements, may also be represented by the suffix "(s)" at the end of the element.
• suffix "(s)" at the end of the element.
• “at least one metal”, “one or more metals”, and “metal(s)” may be used interchangeably and are intended to have the same meaning.
• the present disclosure generally provides an inorganic material that comprises, consists essentially of, or consists of one or more types of a zeolite having a silicon (Si) to aluminum (Al) ratio ranging from about 1 to about 50 or about 2 to about 50 that can absorb malicious species, such as moisture (H2O), free transition- metal ions (TM n+ ), and/or hydrogen fluoride (HF) that may become present or formed within the housing of a lithium-ion secondary battery.
• malicious species such as moisture (H2O), free transition- metal ions (TM n+ ), and/or hydrogen fluoride (HF) that may become present or formed within the housing of a lithium-ion secondary battery.
• the removal of these malicious species prolongs the battery’s calendar and cycle lifetime when the inorganic material is applied to, at least one of, the electrolyte, separator, positive electrode, and negative electrode.
• the inorganic material may also be applied to the inner wall of the housing of the lithium-ion secondary battery.
• the inorganic material acts as a trapping agent or scavenger for the malicious species present within the housing of the battery.
• the inorganic material accomplishes this objective by effectively absorbing moisture, free transition-metal ions, and/or hydrogen fluoride (HF) selectively, while having no effect on the performance of the non-aqueous electrolyte, including the lithium-ions and organic transport medium contained therein.
• the multifunctional inorganic particles may be introduced into the lithium-ion secondary battery or each cell therein as at least one of an additive to the positive electrode, an additive to negative electrode, and additive to the non-aqueous electrolyte, and as a coating material applied to the separator, negative electrode, or positive electrode.
• a secondary lithium-ion cell 1 generally comprises a positive electrode 10, a negative electrode 20, a non-aqueous electrolyte 30, and a separator 40.
• the positive electrode 10 comprises an active material that acts as a cathode 5 for the cell 1 and a current collector 7 that is in contact with the cathode 5, such that lithium ions 45 flow from the cathode 5 to the anode 15 when the cell 1 is charging.
• the negative electrode 20 comprises an active material that acts as an anode 15 for the cell 1 and a current collector 17 that is in contact with the anode 15, such that lithium ions 45 flow from the anode 15 to the cathode 5 when the cell 1 is discharging.
• the contact between the cathode 5 and the current collector 7, as well as the contact between the anode 15 and the current collector 17, may be independently selected to be direct or indirect contact; alternatively, the contact between the anode 15 or cathode 5 and the corresponding current collector 17, 7 is directly made.
• the non-aqueous electrolyte 30 is positioned between and in contact with, i.e., in fluid communication with, both the negative electrode 20 and the positive electrode 10. This non-aqueous electrolyte 30 supports the reversible flow of lithium ions 45 between the positive electrode 10 and the negative electrode 20.
• the separator 40 is placed between the positive electrode 10 and negative electrode 20, such that the separator 40 separates the anode 15 and a portion of the electrolyte 30 from the cathode 5 and the remaining portion of the electrolyte 30.
• the separator 40 is permeable to the reversible flow of lithium ions 45 there through.
• At least one of the cathode 5, the anode 15, the electrolyte 30, and the separator 40 includes an inorganic additive 50A-50D that absorbs one or more of moisture, free transition metal ions, or hydrogen fluoride (HF), as well as other malicious species that become present in the cell.
• the inorganic additive 50A-50D selectively absorbs moisture, free transition metal ions, and/or hydrogen fluoride (HF).
• This inorganic additive 50A-50D may be selected to be one or more types of a zeolite having a silicon (Si) to aluminum (Al) ratio ranging from about 1 and 50; alternatively, between about 2 and 50; alternatively, between about 1 and 25; alternatively, ranging from about 1 to about 20; alternatively, ranging from about 2 to about 15.
• the inorganic additive 50A-50D may be dispersed within at least a portion of the positive electrode 50A (see Figure 1A), the negative electrode 50B (see Figure 1 B), the separator 50C (see Figure 1C), or the electrolyte 50D (see Figure 1 D).
• the inorganic additive 50A-50D may also be in the form of a coating applied onto a portion of a surface of the negative electrode 50B, the positive electrode 50A, or the separator 50C.
• the inorganic additive of the present disclosure comprises at least one or a combination selected from different types of zeolites having a CHA, CHI, FAU, LTA or LAU framework.
• the amount of the inorganic additive present in the secondary cell may be up to 10 wt.%; alternatively, up to 5 wt.%; alternatively, between 0.01 wt.% and 5 wt.%; alternatively, between 0.1 wt.% and 5 wt.%, relative to the overall weight of each component in which the inorganic additive is present, namely, the positive electrode, the negative the electrode, or the electrolyte.
• the amount of the inorganic additive applied as a coating to the negative electrode, positive electrode, or the separator of the secondary cell may be up to 100%; alternatively, at least 90%; alternatively, greater than 5% up to 100%, relative to the amount of the inorganic additive present in the electrochemical cell.
• the inorganic additive may be dispersed within the active material of the negative electrode or incorporated into a coating that is applied to the surface of the active material. The presence of the inorganic additive may further enhance the stability of the negative electrode by limiting the expansion of the anode during operation of the electrochemical cell.
• a coating may be applied using any conventional coating technique. Several examples of such coating techniques include, without limitation, brush coating, spray coating, dip coating, flow coating, roll coating, curtain coating, spin coating, and knife coating.
• the thickness of the coating that includes the inorganic additive may be in the range of 0.10 micrometers (pm) to about 50 micrometers (pm); alternatively, about 0.25 pm to about 40 pm; alternatively, about 0.50 pm to about 30 pm; alternatively, about 1 pm to about 25 pm; alternatively, less than 10 pm; alternatively, less than 7 pm; alternatively, less than 5 pm; alternatively, less than 3 pm; alternatively, between 0.5 micrometers and 10 micrometers.
• the composition of the formulation used to form the coating may include the inorganic additive dispersed in an organic solvent, such that the solvent evaporates after application of formulation to the surface of the active material, thereby, leaving a layer of the inorganic additive on the surface thereof.
• the solvent may be any known organic liquid, including but not limited to aliphatic hydrocarbons, aromatic hydrocarbons, ketones, esters, glcyols, or alcohols. Alternatively, the solvent is naphtha or methyl isobutyl ketone (MIBK), to name a few.
• the composition of the coating formulation may also include a binder material that enhances the adhesion of the inorganic additive to the surface of the active material and/or provides a film forming component for the coating.
• This binder material may be an organic binder or an inorganic binder.
• organic binders include, but are not limited to, oligomers and polymers comprising one or more synthetic or natural resins comprising acrylics, alkyds, phenolics, vinyl-acrylics, vinyl acetate/ethylene (VAE), polyurethanes, polyesters, melamine resins, epoxies, fluoropolymers, silanes, silicones, or mixtures thereof.
• the organic binder is polyvinylidene fluoride (PVDF) or polyvinyl acetate (PVA).
• PVDF polyvinylidene fluoride
• PVA polyvinyl acetate
• inorganic binders include, without limitation, siloxanes, silicates, or liquid glass, to name a few.
• the binder material may be present in an amount that ranges from 0 wt.% to about 20 wt.%; alternatively, between about 1 wt.% and 15 wt.%; alternatively, between about 1 wt.% and 10 wt.%; alternatively, between about 1 wt.% and 5 wt.%; alternatively, less than 15 wt.%; alternatively, less than 10 wt.%, relative to the overall mass of the coating.
• the coating formulation may further include one or more additional additives conventionally used in coatings, such as colorants, pigments, antioxidants, antistatics, fibers, coupling agents, compatibilizers, plasticizers, lubricants, UV stabilizers, fillers, flame retardants, biocides, surfactants or dispersants, and/or other agents that impart desired functions or properties.
• additional additives conventionally used in coatings, such as colorants, pigments, antioxidants, antistatics, fibers, coupling agents, compatibilizers, plasticizers, lubricants, UV stabilizers, fillers, flame retardants, biocides, surfactants or dispersants, and/or other agents that impart desired functions or properties.
• the inorganic additive, solvent, binder material, and any other additives present in the coating formulation may be added together and mixed using any known conventional technique capable of forming a homogeneous dispersion, preferably with minimal agglomeration of particles.
• the dispersion technique that is utilized may include, but not be limited to, the use of hand stirring, an ultrasonicator, a paint shaker, a high shear mixer, a planetary mixer, or a magnetic stirrer.
• the amount of the inorganic additive that is dispersed in the liquid ranges from about 1.0 wt.% to 65 wt.%; alternatively, between about 5 wt.% and 50 wt.%; alternatively, from about 9 wt.% to about 40% by weight relative to the total weight of the liquid dispersion.
• Zeolites are crystalline or quasi-crystalline aluminosilicates comprised of repeating TO4 tetrahedral units with T being most commonly silicon (Si) or aluminum (Al). These repeating units are linked together to form a crystalline framework or structure that includes cavities and/or channels of molecular dimensions within the crystalline structure.
• aluminosilicate zeolites comprise at least oxygen (O), aluminum (Al), and silicon (Si) as atoms incorporated in the framework structure thereof.
• zeolites exhibit a crystalline framework of silica (S1O 2 ) and alumina (AI 2 O 3 ) interconnected via the sharing of oxygen atoms, they may be characterized by the ratio of SiC ⁇ AhOs (SAR) present in the crystalline framework.
• the framework notation represents a code specified by the International Zeolite Associate (IZA) that defines the framework structure of the zeolite.
• a chabazite means a zeolite in which the primary crystalline phase of the zeolite is “CHA”.
• the crystalline phase or framework structure of a zeolite may be characterized by X-ray diffraction (XRD) data.
• XRD X-ray diffraction
• the XRD measurement may be influenced by a variety of factors, such as the growth direction of the zeolite; the ratio of constituent elements; the presence of an adsorbed substance, defect, or the like; and deviation in the intensity ratio or positioning of each peak in the XRD spectrum. Therefore, a deviation of 10% or less; alternatively, 5% or less; alternatively, 1 % or less in the numerical value measured for each parameter of the framework structure for each zeolite as described in the definition provided by the IZA is within expected tolerance.
• the zeolites of the present disclosure may include natural zeolites, synthetic zeolites, or a mixture thereof.
• the zeolites are synthetic zeolites because such zeolites exhibit greater uniformity with respect to SAR, crystallite size, and crystallite morphology, as well has fewer and less concentrated impurities (e.g. alkaline earth metals).
• the inorganic additive 50A-50D may comprise a plurality of particles having or exhibiting a morphology that is plate-like, cubic, spherical, or a combination thereof.
• the morphology is predominately, spherical in nature.
• These particles may exhibit an average particle size (D50) that is in the range of about 0.01 micrometers (pm) to about 15 micrometers (pm); alternatively about 0.05 micrometers (pm) to about 10 micrometers (pm); alternatively, about 0.05 pm to about 5 pm; alternatively, about 0.05 pm to about 3 pm; alternatively, 0.05 micrometers (pm) to about 7.5 micrometers (pm); alternatively, 1 micrometer (pm) to about 5 micrometers (pm); alternatively, greater than or equal to 0.05 pm; alternatively, greater than or equal to 1 pm; alternatively, less than 5 pm.
• SEM scanning electron microscopy
• other optical or digital imaging methodology known in the art may be used to determine the shape and/or morphology of the inorganic additive.
• the average particle size and particle size distributions may be measured using any conventional technique, such as sieving, microscopy, Coulter counting, dynamic light scattering, or particle imaging analysis, to name a few. Alternatively, a laser particle analyzer is used for the determination of average particle size and its corresponding particle size distribution.
• the inorganic additive 50A-50D may also exhibit surface area that is in the range of about 2 m 2 /g to about 5000 m 2 /g; alternatively from about 5 m 2 /g to about 2500 m 2 /g; alternatively, from about 10 m 2 /g to about 1000 m 2 /g; alternatively, about 25 m 2 /g to about 750 m 2 /g.
• the pore volume of the inorganic additive 50A-50D may be in the range of about 0.05 cc/g to about 3.0 cc/g; alternatively, 0.1 cc/g to about 2.0 cc/g.
• the measurement of surface area and pore volume for the inorganic additive may be accomplished using any known technique, including without limitation, microscopy, small angle x-ray scattering, mercury porosimetry, and Brunauer, Emmett, and Teller (BET) analysis. Alternatively, the surface area and pore volume are determined using Brunauer, Emmett, and Teller (BET) analysis.
• the inorganic additive 50A-50D may include a sodium (Na) concentration of less than 6 wt.%; alternatively, less than about 5 wt.%; alternatively, about 0.01 wt.% to 6.0 wt.%; alternatively, about 0.05 wt.% to 6 wt.%; alternatively, about 0.05 wt.% to about 3.0 wt.%; alternatively, greater than 0.25 wt.% and less than 4 wt.%, based on the overall weight of the inorganic additive.
• Na sodium
• the inorganic additive may be a lithium-ion exchanged zeolite, such that the concentration of lithium ion is about 0.05 wt.% to about 25 wt.%; alternatively, about 0.1 wt.% to about 20 wt.%; alternatively, about 0.2 wt.% to about 15 wt.%, based on the overall weight of the inorganic additive.
• the inorganic additive may further include one or more doping elements selecting from K, Mg, Cu, Ni, Zn, Fe, Ce, Li, Na, Al, Mn, Sm, Y, Cr, Eu, Er, Ga, Zr, and Ti.
• the one or more doping elements are selected from K, Mg, Cu, Ni, Zn, Fe, Ce, Sm, Y, Cr, Eu, Er, Ga, Zr, and Ti.
• the active materials in the positive electrode 10 and the negative electrode 20 may be any material known to perform this function in a lithium-ion secondary battery.
• the active material used in the positive electrode 10 may include, but not be limited to lithium transition metal oxides or transition metal phosphates.
• active materials that may be used in the positive electrode 10 include, without limitation, UC0O2, LiNii-x- y COxMn y 02 (x+y£2/3), zLi2Mn03-(1-z)LiNioi-x- yCo x Mn y 02 (x+y ⁇ 2/3), LiMn204, LiNio.5Mn1.5O4, and LiFeP04.
• the active materials used in the negative electrode 15 may include, but not be limited to one or more of graphite, a lithium titanium oxide (e.g., LLTisO ⁇ ), silicon metal or lithium metal.
• the active material for use in the negative electrode is silicon or lithium metal due to their one-magnitude higher specific capacities.
• the current collectors 7, 17 in both the positive 10 and negative 20 electrodes may be made of any metal known in the art for use in an electrode of a lithium battery, such as for example, aluminum for the cathode and copper for the anode.
• the cathode 5 and anode 15 in the positive 10 and negative 20 electrodes are generally made up of two dissimilar active materials.
• the non-aqueous electrolyte 30 is used to support the oxidation/reduction process and provide a medium for lithium ions to flow between the anode 15 and cathode 5.
• the non-aqueous electrolyte 30 may be a solution of a lithium salt in an organic solvent.
• lithium salts include, without limitation, lithium hexafluorophosphate (LiPF 6 ), lithium bis(oxalato)-borate (LiBOB), and lithium bis(trifluoro methane sulfonyl)imide (LiTFSi).
• lithium salts may form a solution with an organic solvent, such as, for example, ethylene carbonate (EC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), propylene carbonate (PC), vinylene carbonate (VC), and fluoroethylene carbonate (FEC), to name a few.
• organic solvent such as, for example, ethylene carbonate (EC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), propylene carbonate (PC), vinylene carbonate (VC), and fluoroethylene carbonate (FEC), to name a few.
• EMC ethyl methyl carbonate
• DMC diethyl carbonate
• PC propylene carbonate
• VC vinylene carbonate
• FEC fluoroethylene carbonate
• a specific example of an electrolyte is a 1 molar solution of LiPF 6 in a mixture of ethylene carbonate and
• the separator 40 ensures that the anode 15 and cathode 5 do not touch and allows lithium ions to flow there through.
• the separator 40 may be a polymeric membrane comprising, without limitation, polyolefin based materials with semi crystalline structure, such as polyethylene, polypropylene, and blends thereof, as well as micro-porous poly(methyl methacrylate)-grafted, siloxane grafted polyethylene, and polyvinylidene fluoride (PVDF) nanofiber webs.
• PVDF polyvinylidene fluoride
• one or more secondary cells may be combined to form a lithium-ion secondary battery.
• a lithium-ion secondary battery 75A is shown in which the four (4) secondary cells of Figures 1A-1 D are layered to form a larger single secondary cell that is encapsulated to produce the battery 75.
• Figures 3A and 3B another example of a battery 75B is shown, in which the four (4) secondary cells of Figures 1A-1 D are stacked or placed in series to form a larger capacity battery 75B with each cell being individually contained.
• the lithium-ion secondary battery 75A, 75B also includes a housing 60 having an internal wall in which the secondary cells 1 are enclosed or encapsulated in order to provide for both physical and environmental protection.
• a battery 75A, 75B may include any other number of cells.
• the battery 75A, 75B may include one or more cells in which the inorganic additive is incorporated with the positive electrode (50A, Figure 1A), the negative electrode (50B, Figure 1 B), the separator (50C, Figure 1C), or the electrolyte (50D, Figure 1 D).
• all of the cells may have the inorganic additive incorporated in the same way, e.g., 50A, 50B, 50C, or 50D.
• the battery 75A, 75B may also include one or more cells in which the inorganic additive 50A-50D is not incorporated or included provided that at least one of the cells in the battery 75A, 75B incorporates the inorganic additive 50A- 50D.
• the housing 60 may be constructed of any material known for such use in the art.
• Lithium-ion batteries generally are housed in three different main form factors or geometries, namely, cylindrical, prismatic, or soft pouch.
• the housing 60 for a cylindrical battery may be made of aluminum, steel, or the like.
• Prismatic batteries generally comprise a housing 60 that is rectangular shaped rather than cylindrical.
• Soft pouch housings 60 may be made in a variety of shapes and sizes. These soft housings may be comprised of an aluminum foil pouch coated with a plastic on the inside, outside, or both.
• the soft housing 60 may also be a polymeric-type encasing.
• the polymer composition used for the housing 60 may be any known polymeric materials that are conventionally used in lithium-ion secondary batteries.
• a soft housing 60 needs to be designed such that the housing 60 provides mechanical protection for the secondary cells 1 in the battery 75.
• the inorganic additive 50E may also be included as a coating applied onto at least a portion of a surface of the internal wall of the housing 60.
• the inorganic additive 50E applied to the internal wall of the housing 60 may be used along with the inclusion of the inorganic additive 50A-50D in one or more of the secondary cells 1 or used separately with secondary cells that do not individually include the inorganic additive 50A-50D.
• the water (H2O) can react with a lithium salt, such as LiPF 6 , resulting in the generation of lithium fluoride (LiF) and hydrogen fluoride (HF).
• a lithium salt such as LiPF 6
• HF hydrogen fluoride
• the lithium fluoride (LiF) which is insoluble, can deposit on the surfaces of the active materials of the anode or cathode forming a solid electrolyte interface (SEI).
• This solid electrolyte interface (SEI) may reduce or retard the lithium-ions (de)intercalation and inactivate the surface of the active material, thereby, leading to a poor rate capability and/or capacity loss.
• Hydrogen fluoride when present, may attack the positive electrode, which contains transition metal and oxygen ions, resulting in the formation of more water and transition metal compounds that are compositionally different from the active material.
• the reactions that occur may become cyclic, resulting in continual damage to the electrolyte and the active material.
• the transition metal compounds that are formed may be insoluble and electrochemically inactive. These transition metal compounds may reside on the surface of the positive electrode, thereby, forming an SEI. On the other hand, any soluble transition metal compounds may dissolve into the electrolyte resulting in transition metal ions (TM n+ ).
• the Mn 2+ , Ni 2+ , and Co 2+ trapping capabilities of the inorganic additives in the organic solvent are analyzed by ICP-OES.
• the organic solvent is prepared, such that it contains 1000 ppm manganese (II), nickel (II), and cobalt (II) perchlorate, respectively.
• the inorganic additive in particle form is added as 1 wt.% of the total mass, with the mixture being stirred for 1 minute, then allowed to stand still at 25°C for 24 hours prior to measuring the decrease of the concentration of Mn 2+ , Ni 2+ , and Co 2+ .
• the separators are fabricated using a monolayer polypropylene membrane (Celgard 2500, Celgard LLC, North Carolina). Separators with and without the inclusion of the inorganic additive are constructed for performance comparison.
• a slurry containing the inorganic additive is coated onto the separator in two-side form.
• the slurry is made of 10-50 wt.% inorganic additive particles dispersed in deionized (D.l.) water.
• the mass ratio of a polymeric binder to the total solids is 1-10%.
• the coating is 5-15 pm in thickness before drying.
• the thickness of the coated separator is 25-45 mih.
• the coated separators are punched into a round disks in a diameter of 19 mm.
• Coin cells (2025-type) are made for evaluating the inorganic additives in a electrochemical situation.
• a coin cell is made with exterior casing, spacer, spring, current collector, positive electrode, separator, negative electrode, and non-aqueous electrolyte.
• a slurry is made by dispersing the active material (AM), such as LiNii 3 Coi /3 Mni /3 0 2 and carbon black (CB) powders in an n-methyl-2-pyrrolidone (NMP) solution of polyvinylidene fluoride (PVDF).
• the mass ratio of AM:CB:PVDF slurry is 90:5:5.
• the slurry is blade coated onto aluminum films. After drying and calendaring, the thickness of each positive electrode film formed is measured to be in the range of 50-150 pm.
• the positive electrode films are punched into round disks in a diameter of 12 mm respectively.
• the mass loading of active material is in the range of 5-15 mg/cm 2 .
• Lithium metal foil (0.75 mm in thickness) is cut into a round disk in a diameter of 12 mm as the negative electrode.
• the cells are cycled between 3 and 4.3 V at the current loadings of C/2 at 25°C after two C/5 formation cycles.
• a FAU-type Y zeolite is used as the inorganic additive, which has been ion- exchanged with Li.
• the particle size is measured as 0.27, 0.43, 3.76 pm for Dio, Dso, and Dgo, respectively.
• the surface area is 640 m 2 /g with the pore volume of 0.23 cc/g.
• the SAR is 3.6, and the inorganic additive contains 0.35 wt.% of Na 2 0 and 6.36 wt.% of U 2 0.
• the inorganic additive reduced the Ni 2+ , Mn 2+ , and Co 2+ in EC/DMC by 63%, 77%, and 84%, respectively. In addition, the inorganic additive scavenges 30% HF in the electrolyte solution.
• a slurry is made with Y zeolite powder and PVA solution. The weight ratio of inorganic powder to polymer binder is 12.5: 1. The solid loading of the slurry is 20%. The slurry is coated in two-side form. The thickness is 7.5 pm for one coating layer. The SEM image of the coated separator is shown in Fig. 4.
• the cell with the conventional bare polypropylene separator shows a discharge capacity of 149.6 mAh/g with 86.1% as coulombic efficiency.
• the cell with the coated separator of the present disclosure exhibits 145.8 mAh/g and 81.2% for the discharge capacity and coulombic efficiency, respectively.
• Coulombic efficiency of each cell reaches above 99.5% after formation cycles. After 100 cycles of C/5 charge-and-discharge, the cell with the coated separator has around 0.5% capacity loss, while the cell with the conventional uncoated separator shows approximately 2% degradation.

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• 2022
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