Invented by Doron Burshtain, Nir KEDEM, Eran SELLA, Daniel Aronov, Storedot Ltd
The Storedot Ltd invention works as followsImproved cells and anodes are provided which allow fast charging rates while enhancing safety, due to a much reduced likelihood of metallization on the anode. This prevents dendrite formation and associated risks of fire and explosion. Anodes or electrolytes can have buffering zones to reduce and introduce lithium ions gradually into the anode, preventing lithium ion buildup at the interface between the anode and electrolyte. “Various anode materials and combinations are available, as well as modifications via nanoparticles. A range of coatings that implement the improved anodes is also provided.
Background for Buffering Zone for Preventing Lithium Metallization on the Anode of Lithium Ion Batteries
The present invention is in the field of energy storage and, more specifically, fast charging lithium-ion batteries.
A major obstacle in battery technology is safety requirements. This is especially true when batteries are overheated, leading to thermal runaway and cell breakdown, as well as possible fire or explosion. A short circuit or design defect can also cause battery failure, which could result in safety and fire risks. While lithium ion batteries have many advantages in terms of performance, they are also flammable because of their high reactivity. This is especially true when in contact humidity.
The following is a simplified overview that provides an initial understanding of this invention. The summary is not intended to identify or limit key elements of the invention. It is merely an introduction.
The present invention includes an anode consisting of anode-active material particles. These particles are equipped with a buffering area at their surface that is configured to receive the lithium ions at the interface between the anode-active material particles and an electrolyte. This buffering area can partly mask the positive charge of these lithium ions received, and allow the partially masked lithium to move to the inner zone of anode-active material particles to lithiate therein.
The detailed description that follows will describe these additional and/or other advantages and/or aspects of the invention. These may be inferred from the detailed descriptions; or learned by practicing the invention.
In the following description are various aspects of the invention described. To provide a better understanding of the invention, certain configurations and specific details are provided for explanation. It will be obvious to those skilled in the art, however, that the invention can be implemented without the specifics presented herein. In order to not obscure the invention, it is possible that well-known features have been simplified or omitted. It is important to note that, with specific reference to the drawing, the details shown are only for illustration and illustrative purposes and are provided to provide what is considered to be the most useful, easily understood description of principles and conceptual aspects. The invention is not described in detail beyond what is required to understand the invention. This description, taken together with the drawings, makes it clear to those of skill in the art, how the various forms of the present invention can be implemented in practice.
Before a detailed description of at least one embodiment is given, it should be understood that this invention does not limit its application to the specific details of the construction and arrangement of components as described in the following description or shown in the drawings. The invention can be applied to other embodiments, which may be carried out or practiced in different ways, as well as combinations of the disclosed examples. It is important to note that terminology and phraseology are used interchangeably.
Improved cells and anodes are provided which allow fast charging rates while enhancing safety, due to a much reduced likelihood of metallization on the anode. This prevents dendrite formation and associated risks of fire and explosion. Anodes or electrolytes can have buffering zones to reduce and introduce lithium ions gradually into the anode, preventing lithium ion buildup at the interface between the anode and electrolyte. “Various anode materials and combinations are available, as well as modifications via nanoparticles. A range of coatings that implement the improved anodes is also provided.
FIG. “FIG. FIG. FIG. 1A shows schematically and in a non-limiting way, the surface of the anode, which can be made up of different size particles (e.g. particles of metalloids like silicon, germanium, or tin and/or particles of lead, zinc, aluminum and/or other metalloids; see below for further details and options. Anode material particles 110 could also include composite particles 115, as described below. The anode is designed to receive lithiated Lithium during charging, and release lithium ions when discharging. Anodes 100 can also include binder(s), additives 102, and optionally coatings (e.g. conductive polymers or lithium polymers). One or more coatings (e.g. conductive polymers or lithium polymers) can be applied to active material particles 110. Borate and/or salts of phosphate 128 may bond to the surface of active material particles 110 (possibly creating B2O3, VC, or TiN, as shown below), and bonding molecules 180 may interact with the electrolyte (and/or additives such as ionic liquids, which are illustrated schematically below). No. No. Anode preparation processes may include, for example, mixing additives 102, such as binder(s), (e.g. polyvinylidenefluoride, PVDF), plasticizers, and/or conductive materials, with a solvent, such as water, organic solvents, (in which anode material has limited solubility), to form an anode-slurry, which is dried, solidified, and placed in contact with an current collector, such as an aluminum or copper metal. Below are details for some of the possible configurations.
It has been noted explicitly that cathodes can be prepared in accordance with disclosed embodiments and the use anode does not limit the scope of invention.” In some embodiments, the term anode can be replaced with electrode or cathode. Cell elements corresponding to the mentioned terms may also be provided. “For example, in cells configured to provide fast charging and discharging, either one or both electrodes 100 and 87 can be prepared according embodiments of this invention.
As disclosed below, “certain embodiments include composite anode materials particles 115 that may be configured into core shell particles. Although the different configurations of anode surfaces are shown schematically, embodiments can include any combination of configurations and any extent of anode with any of the disclosed designs. “Anode(s), 100, may be integrated into cells 150, which can be used to make lithium ion battery, along with cathode (s) 87 and electrolyte (s) 85, separator 86 and other battery components, such as current collectors and electrolyte additives.
The disclosed principles may enable “Anode Material Particles 110, 110A and 115, Anodes 100 and Cells 150 to be configured to allow high charging and/or discharge rates (C rate), ranging from 3-100 C-rate and even higher, such as 5 C, 10 C 15 C 30 C and more. The term C-rate refers to the charging and/or discharge of a cell/battery’s capacity. For example, 1 C represents charging or discharging a cell in one hour. XC is the number of C’s (e.g. 5 C, 10C, 50C etc.). The C-rate is a measure of charging and/or discharge of a cell in an hour.
FIG. FIG. 1B shows a high-level schematic illustration of anode components 105 in a preparation procedure, as well as various anode configurations within a lithium ion battery 150 according to certain embodiments of the present invention. FIG. FIG. 1B shows schematically and in a non-limiting way, a surface anode 100. This may include anode active materials particles 110 (e.g. shell-core particles 115, with cores being metalloid particles such as silicon and/or germanium, and/or tin and/or aluminum, or cores of other materials listed below), binder(s), 102 (for bind particles 110 and/or 115 of the anode to each other, as well as to the current collector See details below. In preparation processes such as ball-milling, active material particles 110 can be coated 120 with various nanoparticles and/or conductive polymers (e.g. B2O3, lithium polymers etc. see below for details) or B4C (see below for details). No. No. Patent documents listed here disclose details for some of these configurations. “The different configurations have been shown schematically on different regions of the surface of the anode, but embodiments can include any combination of these configurations and any extent of surface with any of these disclosed configurations.
In the illustrated configurations, conductive fibres 130 are shown extending throughout anode (100), interconnect cores (110), and interconnected between themselves. The electronic conductivity can be improved by the use of any or all of the following materials: Binder and additives, Coatings 130A and conductive fibers, Nanoparticles and Pre-Coatings. Anode 150 of a lithium ion battery comprises composite anode material, such as core shell particles 115 and electrolyte 86. At least one cathode is used to deliver lithium ions through cell separators 86 during charging. Lithium ions are lithiated when they penetrate the anode materials, such as core-shell particles 110. As particles 115 have been illustrated in a generic and non-limiting manner, any of the composite anode materials and core-shell particle configurations presented below can be used to create anode 100. The shell of core-shell particles 115 may at least partially be provided by coatings 120 and may be configured so as to provide a space 140 to allow anode active materials 110 to expand upon lithiation. In certain embodiments, the gap 140 can be implemented using an elastic or flexible filling material, and/or coating(s) that are flexible enough to extend when anode active materials cores 110 expand (101), and thus effectively provide space for expansion 101 as indicated in FIG. Gap 140 is shown in FIG. 1B, a schematically non-limiting way. Below are examples of both types 140. They can be combined, for example, by providing a small gap 140, but allowing for further expansion through the coating flexibility.
Examples for electrolyte 85 may comprise liquid electrolytes such as ethylene carbonate, diethyl carbonate, propylene carbonate, fluoroethylene carbonate (FEC), EMC (ethyl methyl carbonate), DMC (dimethyl carbonate), VC (vinylene carbonate) and combinations thereof and/or solid electrolytes such as polymeric electrolytes such as polyethylene oxide, fluorine-containing polymers and copolymers (e.g., polytetrafluoroethylene), and combinations thereof. Electrolyte 85 may comprise lithium electrolyte salt(s) such as LiPF6, LiBF4, lithium bis(oxalato)borate, LiN(CF3SO2)2, LiN(C2F5SO2)2, LiAsF6, LiC(CF3SO2)3, LiClO4, LiTFSI, LiB(C2O4)2, LiBF2(C2O4), tris(trimethylsilyl)phosphite (TMSP) and combinations thereof. “Ionic liquids can be added to the electrolyte as shown below.
In certain embodiments, cathode(s) 87 may comprise materials based on layered, spinel and/or olivine frameworks, and comprise various compositions, such as LCO formulations (based on LiCoO2), NMC formulations (based on lithium nickel-manganese-cobalt), NCA formulations (based on lithium nickel cobalt aluminum oxides), LMO formulations (based on LiMn2O4), LMN formulations (based on lithium manganese-nickel oxides) LFP formulations (based on LiFePO4), lithium rich cathodes, and/or combinations thereof. Separator (s) 86 can be made of various materials such as polyethylene, polypropylene or other suitable materials. Below are detailed descriptions of possible compositions for anode(s).
FIG. The prior art is illustrated in FIG. 2A, which is a schematic high-level illustration of the metallization process for lithium ion battery. In typical lithium-ion batteries, graphite is used as anode 95. This material receives lithium ions (from an electrode 85) through an intercalation between graphite sheets. The maximum capacity of graphite is approximately one lithium ion per ca. The SEI formed between the anode 95 and the electrolyte 86, usually on the basal intercalation planes of the graphite, influences the six carbon atoms. These lithium ion battery systems have a low rate of charging and discharging due to the limited charge transfer rates, and the limited diffusion of lithium ions into graphite. The schematic illustration 90A of FIG. As shown schematically in illustration 90A of FIG. The graphite is intercalated with the anode 95. Li+ supply rate limits the intercalation rate. As the charging rates increase (symbols 90B-90D show increasing charging rates in comparison to 90A), so does the rate of lithium ions. Lithium ions then accumulate at the interface (solid-electrolyte surface) (of anode materials 95 or their particles), as shown in 90B. This accumulation rate is greater than the intercalation of lithium ions. In 90C it is shown schematically that the flow of electrons towards the interface increases without any intercalation of lithium ions in the anode 95. As lithium ion reduction and accumulation at the interface increases (as shown in 90D), dendrite growth and lithium metallization begin at the interface, causing cell damage. “Additional considerations include the volume changes in the graphite electrode, the effects of anode additives on the SEI, and details about the charging and discharge cycles.
Embodiments” of the invention enable fast charging with increased safety, due to a much lower probability of lithium metallization on the anode. This prevents dendrite formation and the associated risks of explosion or fire. Anode material particle buffer zones are used to reduce and introduce lithium ions gradually into the anode, preventing lithium ion buildup at the interface between the anode and electrolyte and metallization. The cell’s electrolyte can be selected to reduce the rate of accumulation of lithium ions on the interface.
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