Additive for electrode active material, a dendrite – free electrode and a battery comprising the same

Abstract

The present invention relates to an additive for an electrode active material comprising 5 wt.% to 90 wt.% of nanoparticles of one or more elements or compounds of Group 14 and / or Group 15, said nanoparticles having an average particle size ranging between 20nm to 500 nm and are selected from Sn, (Sn6O4(OH)4), Sn(OH)2, SnO, SnO2, Si, SiO, SiO2, Ge, and Sb; 5 wt.% to 90 wt.% of one or more carbon source having an average particle size ranging between 20 nm to 500 nm; and optionally 5 wt.% to 90 wt.% of one or more elements or compounds of Group I, wherein wt.% is based on the total weight of the additive.

Description

[0001] Voltrez-202421061520

[0002] 1

[0003] TITLE OF THE INVENTION

[0004] ADDITIVE FOR ELECTRODE ACTIVE MATERIAL, A DENDRITE - FREE ELECTRODE AND A BATTERY COMPRISING THE SAME

[0005] TECHNICAL FIELD

[0006]

[0001] The present invention relates to electrode material additives. More particularly, the present invention relates to an additive for an electrode material that renders the material dendrite-free and significant reduction in plating by more than an order of magnitude.

[0007] BACKGROUND OF THE INVENTION

[0008]

[0002] Batteries are classified according to their rechargeability into primary and secondary batteries. Primary batteries such as alkaline batteries and Aluminium-air batteries are single use items that produce energy by an irreversible chemical reaction that consumes the electrode and / or electrolyte. Primary batteries cannot be recharged once they are depleted. Secondary batteries in comparison can be recharged due to the reversible nature of the chemical reactions they use to produce energy. Secondary batteries can be charged by supplying an external DC power source of reverse polarity to that of the battery terminals and at slightly higher voltage than that produced by the battery itself. During charging the positive active material is oxidised generating free electrons which reduce the negative active material under the influence of the external power source. Common example of secondary batteries includes lead-acid batteries, lithium-ion batteries, lithium polymer batteries, nickel cadmium batteries, nickel metal hydride batteries, etc.

[0009]

[0003] Typically, in a secondary battery two electrodes and an electrolyte are commonly employed with electrochemical reactions proceeding at both electrodes. Commonly used battery types are characterized by their choice of electrolyte and electrode. For instance, lead acid batteries contain lead electrodes (pure lead or lead oxides) in an acidic electrolyte such as sulfuric acid. Metal ion batteries are a type of secondary battery currently in high demand due to their higher power density and favourable charge-discharge properties. Typical examples of metal -ion batteries reported in various studies include sodium, lithium, potassium, magnesium, calcium, and fluorine- ion batteries.

[0010]

[0004] Metal ion batteries use a variety of electrode types based on the desired properties of the battery and the choice of electrolyte. Earlier lithium batteries used pure Li metal sheets or films as the negative electrode (anode) which resulted in certain problems regarding safety and reactivity of the Li metal if contacted by air or water. For this reason, lithium ion and lithium polymer batteries were developed where the modern lithium batteries use conductive carbonaceous Voltrez-202421061520

[0011] 2 materials in construction of the anode.

[0012]

[0005] In addition to carbon, other materials have been included in the construction of anodes for metal ion batteries. These include metal oxides, metal nitrides, metal sulphides, and a range of metals, metal alloys, and intermetallic compounds that can accommodate lithium atoms / ions in stoichiometric and non-stoichiometric quantities. The carbon and transition metal compounds also provide for the intercalation of Li ions in the anode material during the lifespan of the cell. As the cells charge and discharge, Li ions from the electrolyte permeate the anode and deposit along the interface between the anode and the electrolyte. This leads to the formation of a solid electrolyte interface (SEI) layer. During the first charge of a lithium-ion battery, some of the lithium ions become trapped on the anode material surface, forming a solid electrolyte interphase (SEI) layer. This SEI layer is crucial for the battery's long-term stability but results in a loss of active lithium, reducing the battery's initial capacity. This leads to an irreversible loss of capacity which leads to formulated cell having lower actual capacity than ideally required. Additionally, use of compounds such as sulphides leads to significant challenges including loss of metal ions due to formation of metal sulphides. Anodes made of metal sulphide demonstrate poor long-term stability with significant degradation observable after -200 charge-discharge cycles, along with difficulty in synthesis and binder compatibility due to the presence of sulphur in the anode material. To address these shortcomings, a stable and non-degrading material is desired for anode construction.

[0013]

[0006] Pre-lithiation is a process used in the development of lithium-ion batteries to improve their performance and lifespan. It involves the intentional addition of lithium to the anode material before the battery is fully assembled and cycled. This helps to offset the initial loss of lithium that typically occurs during the first charge and discharge cycles, known as the "first cycle irreversible capacity loss." Pre-lithiation compensates for this loss by ensuring there is sufficient lithium available, which can improve the overall energy density and efficiency of the battery.

[0014]

[0007] Pre-lithiation can be achieved through various methods, such as chemical, electrochemical, and mechanical techniques. Each method has its own advantages and challenges, and the choice of method depends on factors like the specific anode material used and the intended application of the battery. For instance, pre-lithiation may be performed by deposition of Li metal through chemical vapour deposition (CVD), physical vapour deposition (PVD) or by electrospinning. These steps add a further complexity to the manufacture of anodes for lithium-ion batteries.

[0015]

[0008] Another problem with the standard anode construction is that over sufficient number of charge and discharge cycles, the electrolyte at the anode chamber decomposes and further causes increase in the thickness of the SEI layer. Typically, this deposition is uneven and results in the growth of Li metal in tree-like structures called dendrites. These dendrites significantly impact Voltrez-202421061520

[0016] 3 performance of the anode and may even grow over time to pierce the separator and contact the cathode, causing internal short-circuiting of the cell.

[0017]

[0009] Several methods and techniques are employed in lithium-ion cell technologies to mitigate dendrite formation and deposition of metallic lithium on the anode surface. Commonly used approaches to reduce dendrite formation include use of electrolyte additives such as lithium salts (e.g., LiNCh, LiTFSI) or other compounds (e.g., fluoroethylene carbonate, FEC); surface coatings on the anode material (e.g., with polymers, ceramics, or conductive carbon materials); optimizing the composition and concentration of electrolyte components such as solvents and salts; use of advanced separator materials that are more resistant to puncture or degradation; controlling the operating temperature range of the battery; implementing current limiting during charging and discharging and employing optimized cycling protocols; Cell design modifications, such as altering the physical structure of the anode or separator and developing solid-state electrolytes that do not rely on liquid components can potentially eliminate the issues associated with liquid electrolytes, including dendrite formation and SEI instability.

[0018]

[0010] These methods are often combined and tailored based on the specific requirements and characteristics of the battery application to achieve the best balance between performance, safety, and longevity. However, none of these are satisfactory in fully solving the problems associated with the dendrite formation. Similar issues also exist with the construction of sodium or other metal ion batteries.

[0019] [Oi l] Further, the uneven adsorption of Li ions needs to be remedied by ensuring that the Li ions released from the electrolyte during the gradual breakdown of the electrolyte are deposited uniformly across the surface of the electrode instead of as dendrites. For this, homogeneous adsorption of Li ions on the surface of the anode is of primary importance.

[0020]

[0012] Thus, there is a need in the art to provide an additive for electrode active material that minimizes dendrite formation on the electrode as well as reduces additional steps in the electrode manufacturing process, without negatively impacting the overall performance of the battery or cell.

[0021] SUMMARY OF THE INVENTION

[0022]

[0013] An aspect of the present invention relates to an additive for an electrode active material. In an embodiment, the additive comprises 5 wt.% to 90 wt.% of nanoparticles of one or more elements or compounds of Group 14 and / or Group 15, 5 wt.% to 90 wt.% of one or more carbon source and optionally 5 wt.% to 90 wt.% of one or more elements or compounds of Group I, wherein wt.% is based on the total weight of the additive. Voltrez-202421061520

[0023] 4

[0024]

[0014] In an embodiment, the Group 14 and / or Group 15 nanoparticles are selected from Sn, (SneO4(OH)4), Sn(OH)2, SnO, SnO2, Si, SiO, SiO2, Ge and Sb, and having an average particle size ranging between 20nm to 500nm.

[0025]

[0015] In another embodiment, the one or more carbon source is selected from carbon black, acetylene black, carbon nanotubes and / or carbon nanofibers, and having an average particle size ranging between 20 nm to 500 nm.

[0026]

[0016] In another embodiment, the elements or compounds of Group I are selected from Li OH, Li2CO3, LiF, LiCl, LiBr, Lil, LiNO3, and Li2SO4.

[0027]

[0017] In another embodiment, the additive further comprises up to 5 wt.% of one or more auxiliaries selected from binding agent, sugar, and organic acid.

[0028]

[0018] Another aspect of the present invention relates to a method of preparing the above additive for electrode active material. In an embodiment, the method comprises mixing one or more elements or compounds of Group 14 and / or Group 15 with a solvent and water to obtain a homogeneous mixture; mixing the homogenous mixture with a chelating agent for a duration ranging between Ih to 4h; adding a pH adjusting agent to the homogeneous mixture to obtain a first suspension; centrifuging the first suspension to obtain a precipitate comprising nanoparticles of one or more elements or compounds of Group 14 and / or Group 15; mixing 5 wt.% to 90 wt.% of the nanoparticles of the elements or compounds of Group 14 and / or Group 15, and 5 wt.% to 90 wt.% of one or more carbon source having an average particle size ranging between 20 nm to 500 nm, followed by drying at a temperature ranging between 60°C to 100°C for a duration ranging between 1 h to 40 h to obtain a nanocomposite comprising the nanoparticles of one or more elements or compounds of Group 14 and / or Group 15 and carbon; mixing 5 wt.% to 90 wt.% of one or more elements or compounds of Group I with the one or more carbon source, the nanocomposite, and up to 5 wt.% of one or more auxiliaries to obtain a second suspension; and drying the second suspension at a temperature ranging between 60°C to 100°C for a duration ranging between 1 h to 40 h to obtain a powder comprising the additive.

[0029]

[0019] In an embodiment, the solvent is selected from deionized water, acetone, and isopropyl alcohol.

[0030]

[0020] In another embodiment, the pH adjusting agent is selected from ammonia, KOH, and NaOH.

[0031]

[0021] In another embodiment, the method further comprises the step of reducing the powder in presence of a reducing agent at a temperature ranging between 600°C to 800°C to obtain nanoparticles of the additive. In an embodiment, the reducing agent is selected from hydrogen, argon, and nitrogen or any combination thereof. Voltrez-202421061520

[0032] 5

[0033]

[0022] Another aspect of the present invention relates to an electrode active material comprising the additive as described above.

[0034] BRIEF DESCRIPTION OF FIGURES

[0035]

[0023] Reference will be made to embodiments of the invention, examples of which may be illustrated in accompanying figures. These figures are intended to be illustrative, not limiting. Although the invention is generally described in context of these embodiments, it should be understood that it is not intended to limit the scope of the invention to these particular embodiments.

[0036] Figure 1 illustrates cyclic voltammetry study of an additive in accordance with an embodiment of the present invention.

[0037] Figures 2(a) and 2(b) illustrate the electrochemical activity of a non-lithiated electrode active material additive in accordance with an embodiment of the invention.

[0038] Figures 3(a) and 3(b) illustrate the electrochemical activity of a lithiated electrode active material additive in accordance with an embodiment of the invention.

[0039] Figure 4 shows an XRD plot of Group 14 / 15 nanoparticles synthesised in accordance with an embodiment of the present invention.

[0040] Figure 5 shows a SEM image of (SneO^OEfE) mixed with 45 nm carbon nanoparticles in accordance with an embodiment of the present invention.

[0041] DETAILED DESCRIPTION OF THE INVENTION

[0042]

[0024] Various features and embodiments of the present invention here will be discernible from the following further description thereof, set out hereunder.

[0043]

[0025] At the outset, it is stated that the terms "comprising", "comprises" and "comprised of' as used herein are synonymous with "including", "includes" or "containing", "contains", and are inclusive or open-ended and do not exclude additional, non-recited members, elements or method steps. It will be appreciated that the terms "comprising", "comprises" and "comprised of' as used herein comprise the terms "consisting of', "consists" and "consists of'.

[0044]

[0026] In the following passages, different aspects of the invention are defined. Each aspect so defined may be combined with any other aspect or aspects unless clearly indicated to the contrary. In particular, any feature indicated as being preferred or advantageous may be combined with any other feature or features indicated as being preferred or advantageous.

[0045]

[0027] Reference throughout this specification to "one embodiment" or "an embodiment" means that a particular feature, structure or characteristic described in connection with the embodiment Voltrez-202421061520

[0046] 6 is included in at least one embodiment of the presently claimed invention. Thus, appearances of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment. Further, the particular features, structures or characteristics may be combined in any suitable manner, as would be apparent to a person skilled in the art from this disclosure, in one or more embodiments. Furthermore, while some embodiments described herein include some, but not other features included in other embodiments, combinations of features of different embodiments are meant to be within the scope of this invention, and form different embodiments, as would be understood by those skilled in the art.

[0047]

[0028] As used herein, the terms “lithiate” and “lithiation” may refer to a process of adding lithium to an electrode active material. Similarly, the terms “sodiate” and “sodiation” may refer to a process of adding sodium to the electrode active material.

[0048]

[0029] As used herein, the terms “charge” and “charging” may refer to a process of providing electrochemical energy to a cell or battery.

[0049]

[0030] Further, the terms “discharge” and “discharging” refer to a process for removing electrochemical energy from a cell or battery, for example, when using the cell or battery to perform desired work.

[0050]

[0031] Furthermore, the term “positive electrode” may refer to an electrode (often called a cathode) where electrochemical reduction occurs during a discharging process. Similarly, the term “negative electrode” may refer to an electrode (often called an anode) where electrochemical oxidation occurs during a discharging process.

[0051]

[0032] An aspect of the present invention is directed towards an additive for an electrode active material.

[0052]

[0033] In an embodiment, the additive comprises 5 wt.% to 90 wt.% of nanoparticles of one or more elements or compounds of Group 14 and / or Group 15, said nanoparticles having an average particle size ranging between 20nm to 500 nm and are selected from Sn, (SneO^OFfy), Sn(OH)2, SnO, SnCh, Si, SiO, SiCh, Ge, and Sb; 5 wt.% to 90 wt.% of one or more carbon source having an average particle size ranging between 20 nm to 500 nm; and optionally 5 wt.% to 90 wt.% of one or more elements or compounds of Group I, wherein wt.% is based on the total weight of the additive.

[0053]

[0034] Group 14 and / or Group 15 of the Periodic Table includes transition metals, particularly having electrically active properties. In an embodiment, the Group 14 and / or Group 15 elements are selected from Sn, Si, Ge, and Sb. The compounds of 14 and / or Group 15 elements include oxides and / or hydroxides thereof. The Group 14 and / or Group 15 elements or compounds possess Voltrez-202421061520

[0054] 7 nano-scale morphology having an average particle size ranging between 20 nm to 500 nm. In an embodiment, the average particle size ranges between 20 nm to 200 nm. In yet another embodiment, the average particle size ranges between 30 nm to 60 nm.

[0055]

[0035] In another embodiment, the one or more carbon source is selected from carbon black, acetylene black, carbon nanotubes and / or carbon nanofibers, and having an average particle size ranging between 20 nm to 500 nm. The carbon source can have different morphologies including micro-scale particulates of carbon such as, but not limited to, carbon black, acetylene black; nanoscale spherical carbons including carbon black, acetylene black, Super P, and the likes; and non- spherical carbons such as single-walled carbon nanotubes, multi-walled carbon nanotubes, and carbon nanofibers.

[0056]

[0036] In another embodiment, the carbon source does not include graphene, graphene composites, and / or their derivatives.

[0057]

[0037] In yet another embodiment, the carbon source has an average particle size in the range of 20 nm to 500 nm. In another embodiment, the average particle size ranges between 45 nm to 100 nm.

[0058]

[0038] In an embodiment, the additive does not include one or more Group 1 element or compound thereof.

[0059]

[0039] In another embodiment, the additive comprises one or more Group 1 element or compound thereof. The Group 1 element is selected from Li or Na. Suitable compounds include LiOH, Li2CO3, LiF, LiCl, LiBr, Lil, LiNO3, and Li2SO4.

[0060]

[0040] In another embodiment, the additive further comprises up to 5 wt.% of one or more auxiliaries selected from binding agent, sugar, and organic acid.

[0061]

[0041] In an embodiment, suitable binders / binding agents include, but are not limited to polyvinylidene fluoride, polyvinyl alcohol, polyacrylic acid, alginic acid, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose (HPC), regenerated cellulose, polyvinylpyrrolidone (PVP), tetrafluoroethylene (TFE), polyethylene (PE), polypropylene (PP), an ethyl ene-propylene- diene terpolymer (EPDM), sulfonated EPDM, styrene-butadiene rubber, and fluorinated rubber. Further, suitable sugars include monosaccharides and / or disaccharides such as but not limited to glucose and sucrose. Furthermore, the organic acids include, but are not limited to, oxalic acid and citric acid.

[0062]

[0042] In an embodiment, the nanoparticles of one or more elements or compounds of Group 14 and / or Group 15 is present in an amount ranging between 5 wt.% to 90 wt.% based on the total weight of the additive. In another embodiment, the one or more carbon source is present in an amount ranging between 5 wt.% to 90 wt.% based on the total weight of the additive. In yet another Voltrez-202421061520

[0063] 8 embodiment, the one or more elements or compounds of Group I is added in an amount ranging between 5 wt.% to 90 wt.% based on the total weight of the additive. In a further embodiment, the one or more auxiliaries and / or chelating agent is added in an amount ranging up to 5 wt.% based on the total weight of the additive.

[0064]

[0043] In a further embodiment, the weight ratio between the one or more elements or compounds of Group 14 and / or Group 15, the one or more carbon source, and the one or more elements or compounds of Group I is 1 : 1 : 1.

[0065]

[0044] Preferably, nanoparticles of the additive are used in the electrode active material. Advantageously, the uniform distribution of the additive assists in uniform distribution of metal ions in a metal-ion battery, thereby minimizing the dendrite formation or rendering the electrode dendrite-free. The presence of additive also ensures that the metal ion adsorption is uniform and in fact, there is a reduced deposition of the free metal ions without forming a bond with the additive or the base active material. Some of the free metal ions accept electron from the anode electrode and become metal and thereby deposits as plated metal. Since the deposition of metal ions reduces due to the additive, hence the conversion from metal ions to metal also reduces. These metal depositions or metal plating occur in a controlled fashion due to the spacing between the additive particles in the electrode and are distributed at a distance from each other on the surface of active material particles preventing the plated metals to agglomerate or nucleate. Thereby the uniform distribution of the additive prevents nucleation of plated metal, which results into elimination of the dendritic structures.

[0066]

[0045] Another aspect of the present invention relates to a method for preparing an additive for an electrode active material. In an embodiment, the additive is the same as described hereinabove. Accordingly, the embodiments pertaining to the additive are applicable here as well.

[0067]

[0046] In another embodiment, the method broadly comprises of synthesizing the nanoparticles of one or more elements or compounds of Group 14 and / or Group 15, followed by formulating the additive by a chemical synthesis route.

[0068]

[0047] In another embodiment, the method comprises the steps of: a. mixing one or more elements or compounds of Group 14 and / or Group 15 with a solvent and water to obtain a homogeneous mixture, b. mixing the homogenous mixture with a chelating agent for a duration ranging between Ih to 4h, c. adding a pH adjusting agent to the homogeneous mixture to obtain a first suspension, d. centrifuging the first suspension to obtain a precipitate comprising nanoparticles of one or more elements or compounds of Group 14 and / or Group 15, Voltrez-202421061520

[0069] 9 e. mixing 5 wt.% to 90 wt.% of the nanoparticles of the elements or compounds of Group 14 and / or Group 15, and 5 wt.% to 90 wt.% of one or more carbon source having an average particle size ranging between 20 nm to 500 nm, followed by drying at a temperature ranging between 60°C to 100°C for a duration ranging between 1 h to 40 h to obtain a nanocomposite comprising the nanoparticles of one or more elements or compounds of Group 14 and / or Group 15 and carbon, f. mixing 5 wt.% to 90 wt.% of one or more elements or compounds of Group I with the one or more carbon source, the nanocomposite, and up to 5 wt.% of one or more auxiliaries to obtain a second suspension, and g. drying the second suspension at a temperature ranging between 60°C to 100°C for a duration ranging between 1 h to 40 h to obtain the additive.

[0070]

[0048] In an embodiment, the solvent is selected from deionized water, acetone, and isopropyl alcohol.

[0071]

[0049] In an embodiment, wherein the pH adjusting agent is selected from ammonia, KOH, and NaOH.

[0072]

[0050] The chelating agent functions to stabilize the nanoparticles in dispersion and prevent excessive agglutination. Suitable chelating agents include, but are not limited to, diethanolamine (DEA), triethanolamine (TEA), ethylenediaminetetraacetic acid (EDTA), citric acid, nitrilotriacetic acid (NTA), diethylenetriaminepentaacetic acid (DTPA), hydroxyethyl ethylenediaminetriacetic acid (HEDTA), glycine, malic acid, tartaric acid, phytic acid, dimercaptosuccinic acid (DMSO), and cyclohexane.

[0073]

[0051] In another embodiment, the method further comprises the step of reducing the powder at a temperature ranging between 600°C to 800°C to obtain the nanoparticles of the additive. The reduction is carried out in the presence of a reducing agent such as, but not limited to, hydrogen, argon, and nitrogen and combinations thereof. The reducing step involves subjecting one or more of the following: SneO OH Sn(OH)2, SnO, SnCE, SiO, and / or SiCE, to a thermal reduction process in presence of a reducing agent at temperatures ranging from 600 °C to 800 °C. This reduction results in the conversion of metal oxides and / or hydroxides into their corresponding elemental (zero-valent) metallic forms, thereby yielding highly conductive nanoparticles. For instance, tin-based compounds such as SneO OH Sn(OH)2, SnO, and / or SnO2 are reduced to form elemental tin (Sn°) nanoparticles, while silicon-based oxides such as SiO and SiO2 are reduced to form elemental silicon (Si0).

[0074]

[0052] Mixing, in the present context, is carried out using suitable mixing means. For instance, the mixing means can be selected from a hydrodynamic shear mixer, a granulator, a ball mill, and Voltrez-202421061520

[0075] 10 the likes. As will be noted above, the present invention mitigates the use of complex methods such as vapor deposition techniques (physical and chemical both) or electrochemical routes. In fact, the present invention provides pre-lithiation or pre-sodiation using a chemical synthesis route.

[0076]

[0053] Another aspect of the present invention relates to an electrode active material comprising the additive, as described hereinabove. Accordingly, the embodiments pertaining to the additive and the method for preparing the additive are applicable here as well.

[0077]

[0054] In an embodiment, the electrode active material comprises suitable amounts of at least the additive, and the one or more carbon sources. Other materials which are generally added to the electrode active material such as but not limited to, binders, solvents, surfactants, and the likes may also be added. The aforesaid ingredients may be added in suitable amounts to achieve the desired effect, i.e., dendrite free structure.

[0078]

[0055] In an embodiment, the electrode active material is an anode active material.

[0079]

[0056] Yet another aspect of the present invention relates to a method for preparing an electrode material for a metal-ion battery comprising the electrode active material, as described hereinabove. The electrode active material comprises the additive. Thus, the embodiments pertaining to the additive, the method for preparing the additive, and the electrode active material are applicable here as well. Further, the method for preparing the electrode material comprising the electrode active material having the additive as described above, may include any techniques known to the person skilled in the art.

[0080]

[0057] Other ingredients that may be mixed with the electrode active material are generally known to the person skilled in the art. For instance, electrically conductive carbon, metal based materials, conductive polymers and the like can be added to the electrode active material.

[0081]

[0058] Still another aspect of the present invention relates to a metal-ion battery comprising the electrode material, as described above, and an electrolyte. Accordingly, the embodiments pertaining to the electrode material are applicable here as well. Suitable examples of metal-ion battery include sodium, lithium, potassium, magnesium, calcium, and fluorine-ion batteries.

[0082]

[0059] The electrode material of the present invention may be employed in any metal-ion battery along with the typical components thereof, such as but not limited to, current collector, electrolyte and separator. The choice and selection of suitable current collector, electrolyte, and separator may vary depending on the metal-ion battery and based on the requirements.

[0083]

[0060] Advantageously, the present invention provides for an improved additive having good electrochemical performance in terms of rate capability and as well as being resistant to dendrite formation over repeated charge and discharge cycles. Further, the additive of the present invention can be pre-lithiated or pre-sodiated depending upon the intended use of the additive in lithium or Voltrez-202421061520

[0084] 11 sodium metal batteries. Moreover, the present invention provides a simple and cost-effective method of lithiating or sodiating the additive without the requirement of complex techniques such as vapour deposition or electrospinning. This enables the metal-ion battery useful for application in electric vehicles, EVToLs (Electric Vertical Take-Off and Landing vehicles), electric trucks, portable electronics, energy storage, and the likes.

[0085] EXAMPLES

[0086]

[0061] The following examples are illustrative of the invention but not limitative of the scope thereof since numerous modifications and variations within the scope of the present invention will be apparent to those skilled in the art. Unless otherwise noted, all parts, percentages and ratios reported in the following examples are on a weight basis.

[0087]

[0062] Example 1 - Synthesis of Tin oxide hydroxide

[0088]

[0063] Experiment 1 A - Synthesis Path 1

[0089] 80 to 120 g of SnCh.2H2O was taken in a container with 80 to 120 ml acetone and 120 to 180 ml deionized (DI) water. The ingredients were mixed for 100-150 mins at 350-450 rpm using a magnetic stirrer, then the stirrer speed was reduced to 180 to 220 rpm and 60 to 80 ml ammonia and 40 to 60 ml DI water was added to the mixture. The mixture was agitated by hand for 5 to 10 mins and mixed for 30 mins at 350 to 450 rpm using the stirrer. The stirrer speed was reduced to 180 to 220 rpm, 120 to 180 ml triethanolamine (TEA) and 40 to 60 ml DI water was added. The mixture was agitated by hand for 5 mins and mixed for 250 to 350 mins at 350-450 rpm using the stirrer.

[0090]

[0064] Experiment IB - Synthesis Path 2

[0091] 80 to 120g of SnC12.2H2O was taken in a container with 80 to 120 ml acetone and 120-to 180 ml DI water. The ingredients were mixed for 100 to 150 mins at 350 to 450 rpm using a magnetic stirrer, then the stirrer speed was reduced to 180 to 220 rpm and 120 to 180 ml triethanolamine (TEA) and 40 to 60 ml DI water was added. The mixture was agitated by hand for 5 to 10 mins and mixed for 100 to 150 mins at 350 to 450 rpm. The stirrer speed was reduced to 180 to 220 rpm and 60 to 80 ml ammonia and 40 to 60 ml DI water was added to the mixture. The mixture was agitated by hand for 5 to 10 mins and mixed for 250 to 350 mins at 350 to 450 rpm using the stirrer.

[0092]

[0065] Experiment 1C - Synthesis Path 3

[0093] 80 to 120g of SnC12.2H2O was taken in a container with 80 to 120 ml acetone and 120 to 180 ml DI water. The ingredients were mixed for 100 to 150 mins at 350 to 450 rpm using a magnetic stirrer, then the stirrer speed was reduced to 180 to 220 rpm and 60 to 80 ml ammonia and 40 to Voltrez-202421061520

[0094] 12

[0095] 60 ml DI water was added to the mixture. The mixture was agitated by hand for 5-10 mins and mixed for 250 to 350 mins at 350 to 450 rpm using the stirrer.

[0096]

[0066] Experiment ID - Synthesis Path 4

[0097] 80 to 120g of SnCh.2H2O was taken in a container with 80 to 120 ml acetone and 120 to 180 ml DI water. The ingredients were mixed for 100 to 150 mins at 350 to 450 rpm using a magnetic stirrer, then the stirrer speed was reduced to 180 to 220 rpm and 60 to 80 ml ammonia and 40 to 60 ml DI water was added to the mixture. The mixture was agitated by hand for 5-10 mins and mixed for 30 mins at 350 to 450 rpm using the stirrer. The stirrer speed was reduced to 180 to 220 rpm, 120 to 180 ml diethanolamine (DEA) and 40 to 60 ml DI water was added. The mixture was agitated by hand for 5 to 10 mins and mixed for 250 to 350 mins at 350 to 450 rpm using the stirrer.

[0098]

[0067] Experiment IE - Synthesis Path 5

[0099] 80 to 120g of SnC12.2H2O was taken in a container with 80 to 120 ml acetone and 120 to 180 ml DI water. The ingredients were mixed for 100 to 150 mins at 350 to 450 rpm using a magnetic stirrer, then the stirrer speed was reduced to 180 to 220 rpm and 120 to 180 ml diethanolamine (DEA) and 40 to 60 ml DI water was added. The mixture was agitated by hand for 5 to 10 mins and mixed for 100 to 150 mins at 350 to 450 rpm. The stirrer speed was reduced to 180 to 220 rpm and 60 to 80 ml ammonia and 40 to 60 ml DI water was added to the mixture. The mixture was agitated by hand for 5 to 10 mins and mixed for 250 to 350 mins at 350 to 450 rpm using the stirrer.

[0100]

[0068] Experiment IF - Synthesis Path 6

[0101] 80 to 120g of SnC12.2H2O was taken in a container with 200 to 300 ml of DI water. The ingredients were mixed for 100 to 150 mins at 350 to 450 rpm using a magnetic stirrer, then the stirrer speed was reduced to 180 to 220 rpm and 120 to 180 ml triethanolamine (TEA) and 40 to 60 ml DI water was added. The mixture was agitated by hand for 5 to 10 mins and mixed for 100 to 150 mins at 350 to 450 rpm. The stirrer speed was reduced to 180 to 220 rpm and 60 to 80 ml ammonia and 40 to 60 ml DI water was added to the mixture. The mixture was agitated by hand for 5 to 10 mins and mixed for 250 to 350 mins at 350 to 450 rpm using the stirrer.

[0102]

[0069] The tin oxide hydroxide precipitate (each starting from 100g SnCh^EEO) synthesised by the above 6 paths were dried at 60 °C and the gravimetric yield (in grams) was measured. The presence of SneO^OEfh was verified using X-Ray diffraction. The comparative XRD plots are given in Figure 4. The results are given in Table 1 below.

[0103]

[0070] Table 1 : Gravimetric yield (in grams) of (SneO^OEfE) produced from 100g SnCh^EEO. Voltrez-202421061520

[0104] 13

[0105]

[0071] The Group 14 and / or 15 nanoparticles produced by Path 2 were utilised for further experiments.

[0106]

[0072] Example 2 - Preparation of Tin oxide hydroxide nanocarbon mixture

[0107]

[0073] The mixture resulting from synthesis path 2 of Example 1 was transferred into a centrifugal tube and centrifuged for 10 to 20mins at 6000 to lOOOOrpm. The supernatant was discarded, and the precipitate was washed by dispersing it in 1 to 2% ammonia aqueous solution. The dispersion was centrifuged again for 10 to 20mins at 6000 to 10000 rpm; the supernatant was discarded. The washing step was repeated again.

[0108]

[0074] The precipitate was transferred to a mixer with 150 to 600 ml of DI water and mixed for 10 to 30 mins. SC45 was added to the solution in 3 steps of 10g to 30g each, along with 250 to 750 ml of DI water. The mixture was mixed at 250 to 350 rpm with manual assistance for 60 to 240 mins and then transferred to a mortar and pestle and granulated for 10 to 45 mins. The granulated mixture was dried at 60°C for 36 hrs. The dried mixture is milled in a ball mill using stainless steel balls of diameter 16mm for 30 min at 200 to 250rpm with additional DI water such that the ratio of mixture: balls = 1 : 10.3 and ratio of mixture: water = 1 :8. The milled mixture was dried at 60°C for 18 to 36 hrs followed by grinding in a mortar and pestle to obtain a fine powder.

[0075] Example 3 - Additive preparation without pre-lithiation

[0109]

[0076] 30 to 70 wt.% of Tin oxide hydroxide nanocarbon mixture produced in Example 2, 25 to 40 wt.% glucose and 1 to 5 wt.% of multi-walled carbon nanotubes (MWCNT) by weight were taken in a ball mill with SS balls of diameter 16mm and milled at 200 to 250 rpm for 30min, wherein total material to ball ratio = 1 : 10. The milled material was passed through a 150 to 250 micron sieve to obtain the finished additive.

[0110]

[0077] Example 4 - Additive preparation with pre-lithiation

[0111]

[0078] 30 to 70 wt.% of Tin oxide hydroxide nanocarbon mixture produced in Example 2, 20 to 30 wt.% glucose, 12 to 22 wt.% lithium hydroxide and 1 to 5 wt.% of multi -walled carbon Voltrez-202421061520

[0112] 14 nanotubes (MWCNT) by weight were taken in a ball mill with SS balls of diameter 16mm and milled at 200 to 250 rpm for 20 to 30min, wherein total material to ball ratio = 1 : 10. The milled material was passed through a 150 to 250 micron sieve to obtain the finished additive.

[0113] Example 5 - Preparation of electrode material comprising additive of Example 3

[0114]

[0079] 10 to 20 wt.% of additive (as produced by Example 3) and 80 to 90 wt.% of natural graphite were taken and milled in a ball mill using SS balls of diameter 16mm for 20 to 30 min at 200 to 250 rpm with additional water such that the ratio of mixture: balls = 1 :4.65 and ratio of mixture: water = 1 :0.9. The milled mixture was dried for 6 to 12hrs at 60°C and the dried mixture was transferred to a mortar and pestle with 0.8 to 1 times DI water by weight. The mixture was granulated for 20 to 30 mins and dried at 60°C for 6 to 12 hrs. The above granulation step was repeated one or more times to obtain a finely granulated mixture.

[0115]

[0080] The granulated mixture was milled using Zirconia balls of diameter 3mm at 320rpm for 120 min wherein ratio ofmixture to balls was 1:5 and was passed through 150 to 250 micron sieve. The sieve material was heated at 650-800°C under Ar-EE atmosphere (2 to 5 hr reaching time, 3 to 7 hr holding time). Any foreign particles on the top layer were removed and the material was milled using Zirconia balls of diameter 3mm at 250 to 350 rpm for 20 to 40 min wherein ratio of material to balls was 1 :5. The milled material was passed through 45 to 125 -micron sieve to obtain the Sn-Graphite based composite. The composite was observed to be a free flowing black coloured powder. This composite was used for preparation of electrode material.

[0116]

[0081] Example 6 - Preparation of electrode material comprising the additive of Example 4

[0117]

[0082] 10 to 20% of additive (as produced by Example 4) and 80 to 90% of natural graphite by weight were taken and milled in a ball mill using SS balls of diameter 16mm for 20 to 30 min at 200 to 250rpm with additional water such that the ratio of mixture: balls = 1 :5 and ratio of mixture: water = 1 :0.9. The milled mixture was dried for 6 to 12hrs at 60°C and transferred to a mortar and pestle with 0.8 to 1 times DI water by weight. The mixture was granulated for 20 to 30 mins and dried at 60°C for 6 to 12 hrs. The above granulation step was repeated one or more times to obtain a finely granulated mixture.

[0118]

[0083] The granulated mixture was milled using Zirconia balls of diameter 3mm at 300 to 350rpm for 100 to 150 min wherein ratio of mixture to balls is 1 :5. The milled mixture was passed through 150 to 250 micron sieve. The sieve material was heated at 650-800°C under Ar-H2 atmosphere (3 hr reaching time, 4 hr holding time). Any foreign particles on the top layer were removed and the material was milled in a ball mill using Zirconia balls of diameter 3mm at 300 to 350rpm for 30 min wherein ratio of material to balls is 1 :5. The milled material was passed through 45 to 125 micron sieve to obtain the lithiated Sn-Graphite composite. This composite is used for preparation Voltrez-202421061520

[0119] 15 of electrode material.

[0120]

[0084] Example 7 - Characterization of the electrode active material additives

[0121]

[0085] The additives produced by the above process were characterised by Scanning Electron Microscopy (SEM). The results are displayed in Figure 5. As will be noted, the average particle size of the additive is in between 30 to 100 nm and the average particle size of nanocarbon (Super C45) is 45 nm.

[0122]

[0086] Example 8 - Cyclic voltammetry analysis of electrode active material additive of Example

[0123] 4

[0124]

[0077] The additive as produced by Example 4 was reduced under EE gas at 800 °C to convert it into Sn nanoparticles. Cyclic voltammetry of the material was performed at 0.5 mV s'1sweep rate for lithium ion battery. The result is illustrated in Figure 1. X-axis of Figure 1 shows Voltage vs Li Metal, in V: The potential (voltage) is swept typically in a forward and reverse direction in a cyclic manner, relative to a lithium metal reference electrode. This range here is 0 to 2.5 V vs. Li / Li. Further, the Y-axis of Figure 1 shows Current, in mA: The measured current response of the cell due to redox reactions occurring during the voltage sweep. Initial Cathodic Sweep (Forward Scan - Lower Curve) Starts from ~2.5 V and moves toward 0 V. Sharp drop in current below ~0.6 V: Indicates electrochemical reduction — likely lithiation of the active material.

[0125]

[0078] Multiple reduction peaks (e.g., near 0.6 V, 0.4 V, and 0.2 V): These represent stepwise reduction of the electrode material, possibly involving Initial SEI (solid electrolyte interphase) formation. Reduction of Sn4+to Sn2+, then to Sn°. Alloying reactions such as LixSn formation.

[0126]

[0079] Reverse Sweep (Anodic Scan - Upper Curve): Sweep from 0 V back to 2.5 V. Oxidation peaks in the range of -0.5 to 0.9 V: Correspond to delithiation or dealloying processes — likely Li-Sn dealloying.

[0127]

[0080] Result: The electrode active material of the present invention is electrically active. That is, it does not increase any dead mass.

[0128]

[0081] Example 9 - Electrochemical analysis of electrode active material additives

[0129]

[0082] The electrode active material additives were taken individually and hydrogenated using 10% EE - 90% Ar mixed gas at 700 to 750 °C and converted into electro-active material. Then the material was used to make electrodes which has been tested in 2016 coin cell format against lithium metal. The result for non-lithiated additive (as produced by Example 3) is given in Figures 2(a) and 2(b), and the result for lithiated additive (as produced by Example 4) is given in Figures 3(a) and 3(b).

[0130]

[0083] X-axis of Figures 2 and 3 show Capacity (mAh): This shows how much charge is stored during the process — representing the amount of lithium inserted or removed from the electrode Voltrez-202421061520

[0131] 16 material.

[0132]

[0084] Y-axis of Figures 2 and 3 show Voltage (V vs Li+ / Li): This indicates the potential of the electrode as a function of lithium insertion (discharge) or removal (charge).

[0133]

[0085] The curve in Figures 2(a) and 3(a) decreases from ~2.5 V to ~0 V — a typical discharge profile, likely during the lithiation of the additive material. This confirms the formation of LixSn at multi-step lithation process. Further, in Figures 2(b) and 3(b), additionally the curve decreases from ~0 V to ~2.5 V — a typical charge profile, likely during the de-lithiation of the additive material. This confirms the reverse electrochemical reaction of LixSn at multi-step de-lithation process. Result: Based on the testing, the non-lithiated additive showed capacity of 1062 mAh / gm of converted Sn whereas the lithiated additive showed capacity of 1146 mAh / gm of converted Sn. In comparison, the capacity of conventional graphite anode is in range of 330 to 346 mAh / gm.

[0134]

[0086] The foregoing description of the invention has been set merely to illustrate the invention and is not intended to be limiting. While the present invention has been described with respect to certain embodiments, it will be apparent to those skilled in the art that various changes and modification may be made without departing from the scope of the invention as defined in the following claims.

Claims

Voltrez-20242106152017CLAIMS1. An additive for an electrode active material comprising:(a) 5 wt.% to 90 wt.% of nanoparticles of one or more elements or compounds of Group 14 and / or Group 15, said nanoparticles having an average particle size ranging between 20nm to 500 nm and are selected from Sn, (SneO4(OH)4), Sn(OH)2, SnO, SnO2, Si, SiO, SiO2, Ge, and Sb,(b) 5 wt.% to 90 wt.% of one or more carbon source having an average particle size ranging between 20 nm to 500 nm, and(c) optionally 5 wt.% to 90 wt.% of one or more elements or compounds of Group I, wherein wt.% is based on the total weight of the additive.

2. The additive as claimed in claim 1, wherein the carbon source is selected from carbon black, acetylene black, carbon nanotubes, and carbon nanofibers.

3. The additive as claimed in claim 1, wherein the elements or compounds of Group I is selected from LiOH, Li2CO3, LiF, LiCl, LiBr, Lil, LiNCh, and Li2SO4.

4. The additive as claimed in claim 1 further comprising up to 5 wt.% of one or more auxiliaries selected from binding agent, sugar, and organic acid.

5. A method for preparing the additive as claimed in claim 1 for an electrode active material, said method comprising the steps of:(a) mixing one or more elements or compounds of Group 14 and / or Group 15 with a solvent and water to obtain a homogeneous mixture,(b) mixing the homogenous mixture with a chelating agent for a duration ranging between Ih to 4h(c) adding a pH adjusting agent to the homogeneous mixture to obtain a first suspension,(d) centrifuging the first suspension to obtain a precipitate comprising nanoparticles of one or more elements or compounds of Group 14 and / or Group 15,(e) mixing 5 wt.% to 90 wt.% of the nanoparticles of the elements or compounds of Group 14 and / or Group 15, and 5 wt.% to 90 wt.% of one or more carbon source having an average particle size ranging between 20 nm to 500 nm, followed by drying at a temperature ranging between 60°C to 100°C for a duration ranging between 1 h to 40 h to obtain a nanocomposite comprising the nanoparticles of one or more elements or compounds of Group 14 and / or Group 15 and carbon,Voltrez-20242106152018(f) mixing 5 wt.% to 90 wt.% of one or more elements or compounds of Group I with the one or more carbon source, the nanocomposite, and up to 5 wt.% of one or more auxiliaries to obtain a second suspension, and(g) drying the second suspension at a temperature ranging between 60°C to 100°C for a duration ranging between 1 h to 40 h to obtain a powder comprising the additive.

6. The method as claimed in claim 5, wherein the solvent is selected from deionized water, acetone, and isopropyl alcohol.

7. The method as claimed in claim 5, wherein the pH adjusting agent is selected from ammonia, KOH, and NaOH.

8. The method as claimed in claim 5 further comprising the step of reducing the powder in presence of a reducing agent at a temperature ranging between 600°C to 800°C to obtain nanoparticles of the additive.

9. The method as claimed in claim 8, wherein the reducing agent is selected from hydrogen, argon, and nitrogen.

10. An electrode active material comprising the additive as claimed in one or more of claims1 to 4 or obtained according to the method as claimed in one or more of claims 5 to 9.

Images