Electrochemically active interlayers for rechargeable batteries

Abstract

The present disclosure provides a rechargeable battery, which includes a negative electrode, a positive electrode, an electrolyte in contact with the negative electrode and the positive electrode, and an intermediate layer disposed in the electrolyte between the negative electrode and the positive electrode, wherein the negative electrode is configured to allow one or more dendrites to grow in a direction from the negative electrode to the intermediate layer to electrically couple the negative electrode to the intermediate layer; the intermediate layer is configured to electrochemically react with cations present in the electrolyte when an electrical coupling is formed between the negative electrode and the intermediate layer, thereby inhibiting the one or more dendrites from growing in a direction from the intermediate layer to the positive electrode. The present disclosure also provides an intermediate layer disposed between the negative electrode and the positive electrode in the electrolyte of a rechargeable battery, wherein the intermediate layer inhibits the growth of one or more dendrites in a direction from the intermediate layer to the positive electrode.

Description

[0001] Related Applications

[0002] This application claims the benefit of Singapore Patent Application No. 10201806028W filed on July 13, 2018, the entire contents of which are incorporated herein by reference for all purposes. Technical Field

[0003] The present disclosure relates to a rechargeable battery. The present disclosure also relates to an intermediate layer that can be disposed between a negative electrode and a positive electrode in a rechargeable battery, wherein the intermediate layer inhibits one or more dendrites from growing in a direction from the intermediate layer to the positive electrode. Background Art

[0004] Rechargeable batteries are widely used as power sources for various electronic devices, including electric vehicles (EVs), mobile phones, and laptops. They have also found applications in EVs and grid storage. Although rechargeable batteries have been widely used, there are still concerns about their safety. For example, there seem to be many fires / explosions related to the use of rechargeable batteries in the past decade.

[0005] The three main components of a rechargeable battery are a positive electrode, a negative electrode, and an electrolyte. In practice, the positive electrode and the negative electrode are usually electrically isolated by a thin porous separator. The separator may be filled with an electrolyte to provide ionic conductivity. Various rechargeable batteries have been developed based on the electrochemical reaction between the positive electrode and the negative electrode, such as lithium-ion batteries, lithium-sulfur batteries, lithium-air batteries, sodium-ion batteries, sodium-sulfur batteries, sodium-air batteries, and zinc-air batteries. Some of these batteries use ionic host materials for the positive and negative electrodes (e.g., lithium-ion batteries and sodium-ion batteries). Therefore, they can be regarded as metal-free batteries. Other batteries may use metals as negative electrodes (e.g., lithium-sulfur batteries, lithium-air batteries, sodium-sulfur batteries, sodium-air batteries, and zinc-air batteries). In various cases, rechargeable batteries have serious problems with the growth of metal dendrites. This is the main cause of battery safety issues.

[0006] For example, in lithium-ion batteries, even if they are designed and manufactured to contain no lithium metal, lithium metal may still be deposited on the negative electrode during charging (reduction on the negative electrode side) under harsh conditions (such as overcharging and excessive current). The deposited lithium may grow across the separator in the form of dendrites. Since the two electrodes are bridged by lithium dendrites, internal short circuits may occur, resulting in safety issues.

[0007] Similarly, other metal-free rechargeable batteries, such as sodium-ion batteries, experience potential growth of metal dendrites that may cause safety issues.

[0008] Depending on the electrochemistry of the rechargeable battery, different metal dendrites may grow. For example, lithium dendrites and sodium dendrites may grow in lithium-ion batteries and sodium-ion batteries, respectively. The dendrite problem may be more severe for some rechargeable batteries based on metal anodes (such as lithium, sodium, and zinc) compared to metal-free batteries. This may be because metal dendrites grow more easily in these metal anode-based batteries during cycling. In fact, the safety associated with metal dendrite growth is often one of the main reasons why the commercialization of these metal anode-based batteries is still limited.

[0009] To overcome the growth of metal dendrites in rechargeable batteries, many efforts have been made to develop dendrite-free metal plating technologies by using modified advanced electrolytes and separators, and by using in situ formed or artificial membranes to improve the electrode / electrolyte interface. Improved and advanced solid / polymer electrolytes, separators, and artificial membranes can also be used to physically inhibit the growth of dendrites. Although these methods can help improve the stability of metal anodes and improve the cycle life / shelf life of rechargeable batteries, none of them can completely overcome the growth of dendrites. Alternatively, researchers have proposed to remove metal dendrites by reacting with a chemically active layer located between the positive and negative electrodes and electrically isolated from the negative electrode. Given the thickness of the active layer, the effectiveness of such a chemically active layer is limited because it tends to react with only a limited amount of metal dendrites. This is because after the local point of the chemically active layer (the point of contact with the metal dendrite) and the nearby part that reacts with the metal dendrite is still full of metal ions, the metal dendrite continues to grow and reaches the positive electrode, resulting in a short circuit. In short, controlling the growth of metal dendrites remains a challenge for rechargeable batteries suffering from the dendrite problem.

[0010] Therefore, it is necessary to provide a solution to solve and / or improve the above problems. The solution should at least improve the use safety and charging safety of the rechargeable battery. Summary of the invention

[0011] In a first aspect, there is provided a rechargeable battery comprising:

[0012] negative electrode;

[0013] positive electrode;

[0014] an electrolyte in contact with the negative electrode and the positive electrode; and

[0015] An intermediate layer is arranged between the negative electrode and the positive electrode in the electrolyte, wherein the negative electrode is configured to allow one or more dendrites to grow in a direction from the negative electrode to the intermediate layer to electrically couple the negative electrode to the intermediate layer; and the intermediate layer is configured to electrochemically react with cations present in the electrolyte when an electrical coupling is formed between the negative electrode and the intermediate layer, thereby inhibiting the one or more dendrites from growing in a direction from the intermediate layer to the positive electrode.

[0016] On the other hand, the present invention provides an intermediate layer that can be set between a negative electrode and a positive electrode in the electrolyte of a rechargeable battery, wherein the negative electrode is configured to allow one or more dendrites to grow in a direction from the negative electrode to the intermediate layer to electrically couple the negative electrode to the intermediate layer; and the intermediate layer is configured to electrochemically react with cations present in the electrolyte when an electrical coupling is formed between the negative electrode and the intermediate layer, thereby inhibiting the growth of the one or more dendrites in a direction from the intermediate layer to the positive electrode. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The accompanying drawings are not necessarily drawn to scale, but emphasis is generally placed on illustrating the principles of the invention. In the following description, various embodiments of the present disclosure are described with reference to the following drawings, in which:

[0018] Figure 1A Schematic diagram of a test cell with an active FeOOH layer at the first lithium dendrite growth stage. This is discussed in Example 1B.

[0019] Figure 1B Schematic diagram of a test cell with an active FeOOH layer at the second lithium dendrite growth stage. This is discussed in Example 1B.

[0020] Figure 1C shows that at 4 mA cm -2 As long as the potential of the FeOOH layer is higher than the potential of the plated lithium, the growth of lithium dendrites can be suppressed in this layer.

[0021] Figure 2A Schematic diagram of a test cell without an active layer at the first lithium dendrite growth stage. This is discussed in Comparative Example 1.

[0022] Figure 2B Schematic diagram of a test cell without an active layer at the second lithium dendrite growth stage. This is discussed in Comparative Example 1.

[0023] Figure 2C shows that at 4 mA cm -2 The voltage curve between different terminals of a battery under a certain current.

[0024] Figure 3A It is a schematic diagram for explaining the design and working principle of the double negative electrode method. Specifically, Figure 3A A conventional battery configuration is depicted. A dendrite grows through the separator, causing the battery to short-circuit.

[0025] Figure 3B Schematic diagram showing the design and working principle of the dual negative electrode method. Specifically, Figure 3B A cell having an intermediate layer disposed between but electrically isolated from the positive and negative electrodes is shown. The growth of dendrites stops in the intermediate layer because Li + The ions undergo an electrochemical reaction with the second negative electrode, replacing the dendrite growth.

[0026] Figure 4 A model for simulating the current and potential distribution on a second negative electrode with a lithium dendrite bridging the center during charging is shown.

[0027] Figure 5A Compared with Figure 1A and Figure 2A Electrolyte-impregnated separators with and without FeOOH layers used in Figure 5A Shown are Nyquist plots of electrochemical impedance spectroscopy (EIS) measurements performed on cells with and without a FeOOH layer.

[0028] Figure 5B A cell for measurement without a FeOOH layer is schematically shown. The resistance of the cell without a FeOOH layer is about 2.6Ω.

[0029] Figure 5C The cell with the FeOOH layer used for measurement is schematically shown. The resistance of the cell with the FeOOH layer is about 3.5Ω. -2 When the discharge current flows through the diaphragm, Figure 5B The increased resistance of the cell with the interlayer produces a voltage drop of about 1 mV compared to the cell without the interlayer. This tiny voltage drop is negligible for practical applications.

[0030] Fig. 6A Compared with Figure 1A and Figure 2A Cell performance with and without FeOOH layer used in. 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (NCM, 3M Company) electrode was used as the working electrode, and lithium metal was used as the counter electrode for measurement. Specifically, Fig. 6A shows that at 30mA g -1 Comparison of typical charge / discharge curves under .

[0031] Figure 6B Compared with Figure 1A and Figure 2A The performance of the cells with and without FeOOH layer used in Figure 6B A comparison of rate performance and cycle characteristics is shown. The results show that the separator with the FeOOH layer (PE / FeOOH / Au / PE) does not impair the battery performance in terms of capacity and rate performance compared to pure polyethylene (PE). Moreover, the separator with the intermediate layer supports better cycle characteristics.

[0032] Figure 7 A scanning electron microscope (SEM) image of gold-coated PE is shown, particularly depicting the porous structure of the separator. The scale bar is 1 μm.

[0033] Figure 8 The Nyquist plot of EIS measurement performed on the Au-coated side of the Au-coated PE with a width (W) of 0.65 cm and a length (L) of 0.45 cm is shown. According to the measurement results, the resistance (R) is about 9.1Ω. The sheet resistance (Rs) is calculated as 6.3Ωsq according to the formula Rs = RW / L -1 .

[0034] Fig. 9 The SEM image of FeOOH used in the experiment is shown. FeOOH has a rod-like appearance. The scale bar is 1 μm.

[0035] Fig.10 A transmission electron microscope (TEM) image of FeOOH used in the experiment is shown. FeOOH has a rod-like appearance. The scale bar is 0.2 μm.

[0036] Fig.11A The morphology of the prepared FeOOH coating is shown. Specifically, Fig.11A An SEM image of the FeOOH coating is shown. In addition to the rod-shaped FeOOH, nanoparticles of the Super P carbon additive can also be found. The scale bar is 2 μm.

[0037] Fig. 11B The capacity of the prepared FeOOH coating is shown. Specifically, Fig. 11B The first discharge capacity of the FeOOH coating prepared on PE is shown. The FeOOH coating is at 4 mA cm -2 The current is about 3.5 mAh cm -2 High capacity.

[0038] Fig. 12A This is a photo of the thickness measurement of pure PE. The measured thickness is 0.011mm.

[0039] Fig. 12B This is a photograph of the thickness measurement of FeOOH coated PE. The measured thickness is 0.040 mm. DETAILED DESCRIPTION

[0040] The following detailed description refers to the accompanying drawings, which illustrate by way of illustration the specific details and embodiments in which the present invention may be implemented. These embodiments are described in sufficient detail herein to enable those skilled in the art to implement the present invention. Other embodiments may be utilized and may be changed without departing from the scope of the present invention. The various embodiments need not be mutually exclusive, as some embodiments may be combined with one or more other embodiments to form new embodiments.

[0041] The features of the embodiments described in the context may be applied accordingly to the same or similar features in other embodiments. Even if not explicitly described in these other embodiments, the features of the embodiments described in the context may be applied accordingly to the other embodiments. In addition, the addition and / or combination and / or substitution described for the features of the embodiments in the context may be applied accordingly to the same or similar features in other embodiments.

[0042] The present disclosure provides a strategy for suppressing the growth of metal dendrites in a rechargeable battery by an electrochemical reaction between an intermediate layer and ions from a positive electrode. The scheme of the present invention relates to an intermediate layer that can electrochemically suppress the growth of metal dendrites in a rechargeable battery. The scheme of the present invention improves the safety of use and charging of the rechargeable battery.

[0043] During charging, metal tends to form at the negative electrode of a rechargeable battery. For example, lithium ions tend to form at the negative electrode of a lithium-ion battery (LIB). During the charging process, the amount of metal formed on the negative electrode increases. The growing metal is referred to herein as a metal dendrite or a dendrite of a metal. As more metal forms on the negative electrode, the dendrite grows out of the negative electrode and extends toward the positive electrode during charging. Once the dendrite contacts the positive electrode, electrons from the negative electrode can pass through the dendrite to the positive electrode. The dendrite forms a bridge that electrically couples the negative electrode to the positive electrode, causing a short circuit in the rechargeable battery. This short circuit can cause safety issues, including fire and / or explosion of the rechargeable battery. The term "electrically coupled" and its grammatical variants as used herein refer to connecting at least two components so that electrons can flow between the components.

[0044] The solution of the present invention advantageously avoids internal short circuits caused by, for example, the growth of lithium dendrites. The growth of lithium dendrites in low-potential negative electrodes is the cause of LIB safety issues. Adequately addressing the growth of lithium dendrites remains a huge challenge. The solution of the present invention can be regarded as a "dual negative electrode" approach that completely prevents the growth of lithium dendrites. The solution of the present invention introduces an intermediate layer that can act as a second negative electrode in the LIB only when lithium dendrite growth occurs and the dendrites are in contact with the intermediate layer. After the dendrites grow, the Li + The ions may be consumed by the second negative electrode without causing dendrites to grow to the positive electrode, which would otherwise cause a short circuit, as described above. By virtue of the advantage of inhibiting the growth of lithium dendrites, the scheme of the present invention can reduce the incidence of spontaneous combustion in electric vehicles, mobile phones, laptops and other devices using LIBs.

[0045] Therefore, various embodiments of the first aspect relate to a rechargeable battery, comprising a negative electrode, a positive electrode, an electrolyte in contact with the negative electrode and the positive electrode, and an intermediate layer disposed in the electrolyte between the negative electrode and the positive electrode, wherein the negative electrode is configured to allow one or more dendrites to grow in a direction from the negative electrode to the intermediate layer to electrically couple the negative electrode to the intermediate layer; the intermediate layer is configured to electrochemically react with cations present in the electrolyte when an electrical coupling is formed between the negative electrode and the intermediate layer, thereby inhibiting the one or more dendrites from growing in a direction from the intermediate layer to the positive electrode. The cations may include lithium ions.

[0046] The positive electrode can be used as a cation source, such as a metal cation, such as Li + ions, depending on the material used to form the positive electrode. For example, when sulfur and V2O5 are used as positive electrode materials, they initially do not contain Li + ions. However, after the first discharge of a rechargeable battery, the positive electrode may be lithiated and contain Li + During charging, however, the positive electrode is operable to generate cations, such as metal cations (eg, lithium ions).

[0047] The rechargeable battery can be connected to an external power source for charging. When the rechargeable battery is charged, oxidation occurs at the positive electrode and results in the production of cations, such as lithium ions. The positive electrode is therefore operable to produce lithium ions. In a typical rechargeable battery being charged, lithium ions migrate in the electrolyte in a direction from the positive electrode to the negative electrode and are deposited on the negative electrode in the form of lithium metal, resulting in the growth of one or more lithium dendrites during the charging process. Lithium ions already present in the electrolyte may also migrate to the negative electrode and be deposited on the negative electrode, resulting in the growth of one or more dendrites during the charging process of the rechargeable battery. One or more lithium dendrites may grow in a direction from the negative electrode to the positive electrode. The intermediate layer inhibits such growth.

[0048] The intermediate layer is disposed between the negative electrode and the positive electrode and is electrically isolated from the negative electrode and the positive electrode. This means that the negative electrode and the positive electrode are not in direct contact with the intermediate layer. Otherwise, a short circuit will occur. The arrangement of the intermediate layer does not make the intermediate layer a barrier that physically prevents dendrites from growing toward the positive electrode. The intermediate layer is also not a barrier that simply chemically reacts with dendrites to prevent dendrite growth. Instead, the intermediate layer is constructed to include one or more active materials. The intermediate layer contains active materials that can electrochemically react with lithium ions to prevent the growth of lithium dendrites. The term "electrochemical reaction" and its grammatical variants are different from typical chemical reactions, which involve the reaction of one material with another material without providing external electrons. The term "electrochemical reaction" as used herein refers to the provision of external electrons to the intermediate layer, and then the active material in the intermediate layer reacts with cations (such as Li + ions) to prevent the growth of, for example, lithium dendrites. The intermediate layer may be referred to as an "active layer" because it includes one or more such active materials.

[0049] The one or more active materials may include Si, Sn, Al, Sb, P, graphite, amorphous carbon, SnSb, SnO, SnO2, MnO2, V2O5, TiO2, FeO, Fe3O4, Fe2O3, FeOOH, FePO4, NiCo2O4, SnS, SnS2, Sb2S3, NiS, Ni3S2, CoS2, CuS, FeS2, NiP3, or a combination thereof. Such active materials are capable of electrochemically reacting with cations (e.g., lithium ions) to prevent dendrites from growing toward the positive electrode.

[0050] The intermediate layer including one or more active materials receives electrons from the negative electrode for the one or more active materials contained in the intermediate layer to electrochemically react with cations when one or more dendrites contact the intermediate layer. As described above, when the rechargeable battery is charged, one or more dendrites may grow from the negative electrode. When growing in the direction of the positive electrode, the dendrite may contact the intermediate layer. When the dendrite contacts the intermediate layer, the dendrite forms a bridge that electrically couples the negative electrode to the intermediate layer, and electrons from the negative electrode can flow to the intermediate layer through the dendrite. The contact of the dendrite with the intermediate layer makes the intermediate layer conductive. Only when one or more dendrites contact the intermediate layer does the intermediate layer become a "second negative electrode", and therefore, the scheme of the present invention may be referred to as a "dual negative electrode" method herein.

[0051] The electrons provided to the intermediate layer cause the active material to electrochemically react with the lithium ions to prevent lithium from being deposited on the intermediate layer, thereby preventing one or more dendrites from growing from the intermediate layer to the positive electrode. The contact between the intermediate layer and the one or more dendrites makes the intermediate layer electrochemically active. When no contact is established, the intermediate layer is not electrochemically active and no electrochemical reaction occurs.

[0052] The intermediate layer is general and may include a non-conductive or conductive active material layer. The layer including the active material may be referred to herein as an "active material layer". An intermediate layer having a non-conductive active material layer does not mean that the intermediate layer cannot inhibit dendrite growth. An intermediate layer having a non-conductive active material layer may still provide an electrochemical reaction that consumes lithium ions (as an example of a cation). For example, an intermediate layer having a non-conductive active material layer may be designed to have a conductive medium that makes the intermediate layer conductive or to be combined with a conductive medium that makes the intermediate layer conductive.

[0053] The intermediate layer may be configured to be conductive. For a conductive intermediate layer, even if one or more dendrites are in contact with the intermediate layer only in certain portions, the entire intermediate layer still provides an electrochemical reaction that consumes cations (eg, lithium ions) because electrons easily flow through the entire conductive intermediate layer.

[0054] The intermediate layer may be formed of an ion-conducting material. After being filled or adsorbed with electrolyte, the intermediate layer may have ion conductivity. This means that the intermediate layer is wetted with electrolyte. The ion-conducting intermediate layer allows lithium ions to flow through the intermediate layer between the negative electrode and the positive electrode so that the rechargeable battery can function properly. The term "ion-conducting" as used herein means that the material allows ion conduction (e.g., migration).

[0055] The interlayer may be porous. The porous interlayer allows electrolyte to be filled in the interlayer, which enhances the cation (e.g., Li + ions) are transported through the middle layer.

[0056] The intermediate layer may be non-porous. The non-porous intermediate layer may also be ionically conductive. For example, the intermediate layer may be formed of a polymer that swells when the intermediate layer is in contact with an electrolyte in the battery. The polymer swelling makes the intermediate layer ionically conductive. Such an intermediate layer absorbs the electrolyte after swelling with the electrolyte and becomes ionically conductive.

[0057] The intermediate layer may include at least one conductive medium, wherein the conductive medium includes copper, gold, nickel, stainless steel, conductive carbon, conductive polymer or a combination thereof. The conductive medium may be disposed near the layer containing the active material. As described above, such a layer containing the active material may be referred to herein as an "active material layer". The conductive medium helps to enhance the conduction of electrons in the intermediate layer. The conductive medium makes the intermediate layer having the non-conductive active material layer conductive. The conductive medium may also be used to establish electrical contact with an external device (e.g., a voltmeter for measuring the voltage of the intermediate layer).

[0058] The intermediate layer can be electrically isolated from the negative electrode and the positive electrode as described above. The intermediate layer can be electrically isolated from the negative electrode and / or the positive electrode by using a separator. The intermediate layer is electrically isolated from the negative electrode and / or the positive electrode by a separator located between (i) the negative electrode and the intermediate layer and / or (ii) the positive electrode and the intermediate layer. This helps to avoid direct contact between the intermediate layer and the negative electrode, direct contact between the intermediate layer and the positive electrode, and / or direct contact between the negative electrode and the positive electrode through the intermediate layer. For illustrative purposes, non-limiting examples of the arrangement of the active material layer, the separator and the conductive medium can be (i) separator / conductive medium / active material layer / separator, (ii) separator / active material layer / conductive medium / separator, (iii) separator / conductive medium / active material layer / conductive medium / separator, or (iv) separator / conductive medium / active material layer / separator / conductive medium / active material layer / separator. In these configurations, the intermediate layer can include a conductive medium and an active material layer. Example (iv) shows that at least one intermediate layer can be combined in the rechargeable battery of the present invention. By way of non-limiting example, the components may be formed adjacent to each other (ie, in physical contact). This is advantageous for reducing the overall thickness of the rechargeable battery. When the thickness is small, the internal resistance of the battery is not significantly compromised.

[0059] The separator may be configured as an ion-conducting membrane. When the separator is immersed in an electrolyte, it may become ion-conductive. The separator may also be an ion-conducting material. This allows lithium ions to pass through, allowing the battery to function properly. The separator may include polyethylene, polypropylene, or a combination thereof. Other commercially suitable separators may also be used.

[0060] The separator can be used as a substrate on which the intermediate layer can be placed. This means that the intermediate layer can be formed as a self-supporting layer, which also means that no other substrate is required to combine with the intermediate layer. Since the intermediate layer can be formed directly on the separator, no intermediary layer is required between the separator and the intermediate layer, which helps to keep the rechargeable battery compact. Without the intermediary layer, the rechargeable battery has no additional resistance or thickness.

[0061] The intermediate layer is not limited to a specific form. The intermediate layer can be a self-supporting layer, can be combined with a substrate, and can also be a multi-layer or a single layer.

[0062] The intermediate layer can be configured to include a binder. The binder helps to keep one or more active materials together in the intermediate layer so that the active materials do not spread out or leach out of the intermediate layer when immersed in the electrolyte. When the intermediate layer is formed by multiple layers, the binder can also hold the intermediate layer together. The binder can include polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyethylene oxide, polytetrafluoroethylene, polyurethane, polyacrylonitrile, polytetraethylene glycol diacrylate, polymethyl methacrylate, sodium carboxymethyl cellulose or a combination thereof.

[0063] The rechargeable battery is operable to have: (i) the potential of the intermediate layer maintained above that of the Li + / Li potential; and (ii) when discharging the rechargeable battery, one or more dendrites retreat from the intermediate layer toward the negative electrode.

[0064] For (i), the intermediate layer is configured to electrochemically react with lithium ions (such as those present in the electrolyte) when electrical coupling occurs between the negative electrode and the intermediate layer. + / Li potential, so an electrochemical reaction occurs, which consumes lithium ions and inhibits the growth of dendrites. + Any material or active material that undergoes electrochemical reaction has a higher potential than Li + / Li. When the battery is operating normally, the potential of the intermediate layer may always be higher than that of Li even during discharge. + / Li potential.

[0065] For (ii), during the discharge of the rechargeable battery, the intermediate layer does not dissolve the dendrites to allow them to retreat toward the negative electrode. As described above, the intermediate layer consumes lithium ions from the positive electrode through the electrolyte because the intermediate layer can inhibit the further growth of dendrites during the charging of the rechargeable battery. During the discharge process, since the oxidation potential of the dendrites is lower than that of the intermediate layer, the dendrites are electrochemically oxidized and dissolved first. The dissolution of the dendrites causes them to retreat from the intermediate layer and interrupts the supply of electrons to the intermediate layer.

[0066] The rechargeable battery with the intermediate layer of the present invention can be used at 0 to 3.5V (vs. Li + / Li) (e.g., voltage between the negative electrode and the intermediate layer) and / or 0.02 to 100 mA / cm 2 The operation of the rechargeable battery having such an intermediate layer is not necessarily limited to such operating conditions as long as the intermediate layer can electrochemically react with lithium ions.

[0067] The intermediate layer may be configured to include or may have an area capacity of 10% to 150% of the area capacity of the positive electrode or negative electrode. Since the capacity of the intermediate layer depends on the capacity of the electrode (e.g., the lithium ion source), the area capacity provided by the intermediate layer can be tailored relative to the area capacity of the positive electrode or negative electrode. This makes the rechargeable battery of the present invention more advantageous because the area capacity of conventional battery electrodes is often limited to 1 to 4 mAh / cm 2 within the range.

[0068] The intermediate layer is configured to include or may have a thickness of less than 2 mm, less than 0.5 mm, less than 0.2 mm, less than 0.1 mm, less than 0.05 mm, less than 0.03 mm, etc. This is advantageous because the introduction of the intermediate layer does not increase the size of the rechargeable battery. This also means that the intermediate layer does not need to be thicker to maintain comparable performance (e.g., capacity) of the rechargeable battery. An intermediate layer with such a thickness can also avoid unnecessary increases in internal resistance. However, if necessary, the thickness of the intermediate layer can be increased to, for example, 6 mm. In this case, the thickness of the intermediate layer can be less than 6 mm.

[0069] The present disclosure also provides an intermediate layer that can be disposed between a negative electrode and a positive electrode in an electrolyte of a rechargeable battery, wherein the negative electrode is configured to allow one or more dendrites to grow in a direction from the negative electrode to the intermediate layer to electrically couple the negative electrode to the intermediate layer; the intermediate layer is configured to electrochemically react with cations present in the electrolyte when an electrical coupling is formed between the negative electrode and the intermediate layer, thereby inhibiting the one or more dendrites from growing in a direction from the intermediate layer to the positive electrode. The cations may include lithium ions.

[0070] The embodiments and advantages described above with respect to the rechargeable battery may be applied to and / or valid for the intermediate layer and its various embodiments, and vice versa.

[0071] For example, as described above, the intermediate layer can be configured to include one or more active materials. The one or more active materials include Si, Sn, Al, Sb, P, graphite, amorphous carbon, SnSb, SnO, SnO2, MnO2, V2O5, TiO2, FeO, Fe3O4, Fe2O3, FeOOH, FePO4, NiCo2O4, SnS, SnS2, Sb2S3, NiS, Ni3S2, CoS2, CuS, FeS2, NiP3 or a combination thereof.

[0072] The intermediate layer can receive electrons from the negative electrode for one or more active materials included in the intermediate layer to electrochemically react with cations (e.g., lithium ions) when one or more dendrites contact the intermediate layer. The intermediate layer can have an active material layer that can be non-conductive, and the intermediate layer can be configured to be conductive. As described above, the intermediate layer having a non-conductive active material layer can contain a conductive medium that makes the intermediate layer conductive. The intermediate layer can be porous or non-porous. The intermediate layer can include at least one conductive medium, wherein the conductive medium includes copper, gold, nickel, stainless steel, conductive carbon, conductive polymers, or a combination thereof. As an example, the conductive medium can be disposed near the layer containing the active material. The intermediate layer can be a self-supporting layer or disposed on a substrate. The substrate may include a diaphragm that can be configured as an ion-conducting membrane. The diaphragm may include polyethylene, polypropylene, or a combination thereof. The embodiments and / or advantages of these features associated with the intermediate layer have been described above in various embodiments of the first aspect, and for the sake of brevity, they will not be repeated here.

[0073] As described above, the intermediate layer may include an adhesive. The adhesive may include polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyethylene oxide, polytetrafluoroethylene, polyurethane, polyacrylonitrile, polyethylene glycol diacrylate, polymethyl methacrylate, sodium carboxymethyl cellulose, or a combination thereof.

[0074] The intermediate layer may be configured to include a thickness of less than 2 mm, less than 0.5 mm, less than 0.2 mm, less than 0.1 mm, less than 0.05 mm, less than 0.03 mm, etc. The advantages of such thickness have been described above in various embodiments of the first aspect of the present invention, and for the sake of brevity, they will not be repeated here. The intermediate layer may also have a thickness of less than 6 mm.

[0075] The word "substantially" does not exclude, for example, "completely". For example, a composition "substantially free of" Y may be completely free of Y. If necessary, the word "substantially" may be omitted from the definition of the present invention.

[0076] In the context of various embodiments, the articles “a,” “an,” and “the” used with respect to features or elements include reference to one or more features or elements.

[0077] In the context of various embodiments, the terms "about" or "approximately" as applied to numerical values ​​encompass the exact value and a reasonable variance.

[0078] As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0079] Unless otherwise stated, the terms "include" and "comprising" and their grammatical variations are intended to represent "open" or "inclusive" language such that they include the recited elements but also allow for the inclusion of additional, non-recited elements.

[0080] Although the above method is shown and described as a series of steps or events, it should be understood that any order of these steps or events should not be interpreted in a restrictive manner. For example, in addition to those steps illustrated and / or described herein, some steps may occur in different orders and / or occur simultaneously with other steps or events. In addition, it may not be necessary to all the steps shown to realize one or more aspects or embodiments described herein. Equally, one or more steps described herein can be carried out in one or more separate actions and / or stages.

[0081] Example

[0082] The present invention relates to at least one intermediate layer that can electrochemically suppress the growth of metal dendrites in a rechargeable battery. The growth of metal dendrites in a rechargeable battery is suppressed by an electrochemical reaction between the intermediate layer and metal ions from a positive electrode. The intermediate layer may include multiple layers and have at least one active material. The at least one active material can electrochemically react with lithium ions from a positive electrode. After filling or adsorbing an electrolyte, the intermediate layer becomes ion conductive. As described above, the layer containing the active material may be referred to as an "active material layer".

[0083] An intermediate layer that electrochemically inhibits the growth of metal dendrites in a rechargeable battery advantageously improves the safety of use and charging of the rechargeable battery. The intermediate layer and the negative electrode in the battery can be electrically isolated by a separator or an ion conductive membrane. During the charging process, when metal dendrites grow from the negative electrode and continue to pass through the separator and / or from the separator (such as an ion conductive membrane) to the intermediate layer, electrons are provided from the negative electrode to the intermediate layer through the dendrite bridge. The intermediate layer can then be regarded as an "additional negative electrode" (i.e., when the dendrites are in contact with the intermediate layer). Electrochemical reduction can occur on the intermediate layer. Ions from the positive electrode side (such as Li in lithium-ion batteries) + ) can electrochemically react with the intermediate layer instead of growing dendrites because it is a thermodynamic configuration (i.e., the electrochemical reaction potential between the intermediate layer and the ions is always higher than the potential of the metal plating). Once the intermediate layer is reduced and consumes ions during charging, it may be difficult to be oxidized and release ions again during discharge (i.e., when the battery is in use). This is because during discharge, the metal dendrites are electrochemically oxidized and dissolved first because their oxidation potential is lower than that of the intermediate layer. Due to the loss of the dendrite bridge, the intermediate layer may have no electron supply. If the intermediate layer has enough capacity to absorb all ions from the positive electrode during a short circuit, the battery may lose all active ion sources in the electrode (such as Li + ). Therefore, safety issues caused by dendrites are advantageously avoided.

[0084] The present invention utilizes the electrochemical reaction between the intermediate layer and the positive electrode to inhibit the growth of dendrites. In principle, the present invention is different from the scheme of inhibiting dendrites by other chemical reactions between the chemically active layer and the dendrites. The present invention is also different from the scheme of physically inhibiting the growth of dendrites.

[0085] The rechargeable battery and interlayer of the present invention are described by way of non-limiting examples as follows.

[0086] Example 1A: Overview of the Materials and Construction of the Intermediate Layer

[0087] The active material in at least one intermediate layer can be any material that can electrochemically react with ions from the positive electrode. For example, for lithium-ion batteries and lithium metal-based batteries, the active materials in the intermediate layer can include Si, Sn, Al, Sb, P, graphite, amorphous carbon, SnSb, SnO, SnO2, MnO2, V2O5, TiO2, FeO, Fe3O4, Fe2O3, FeOOH, FePO4, NiCo2O4, SnS, SnS2, Sb2S3, NiS, Ni3S2, CoS2, CuS, FeS2, and NiP3. The active materials may have high capacity and low potential (relative to the lithium deposition potential), such as Si, Sn, Al, Sb, P, amorphous carbon, SnSb, SnO, SnO2, FeO, Fe3O4, Fe2O3, FeOOH, NiCo2O4, SnS, SnS2, Sb2S3, NiS, Ni3S2, CoS2, CuS, FeS2 and NiP3.

[0088] The intermediate layer may include multiple layers and may include at least one active material layer including at least one active material. The intermediate layer may have an active material layer, which may be conductive or non-conductive. In addition to the active material layer, the intermediate layer may include a conductive medium for improving conductivity. This design may allow the entire or at least a portion of the active layer of the intermediate layer to electrochemically react with ions from the positive electrode when the intermediate layer bridges the dendrite. The intermediate layer having a non-conductive active material layer may contain a conductive medium.

[0089] The intermediate layer may be porous or non-porous.

[0090] In the case where the electrolyte is not filled or adsorbed, the intermediate layer may have ion conductivity or not. After the electrolyte is filled or adsorbed, the intermediate layer that does not have ion conductivity may become ion conductive.

[0091] The interlayer may be self-supporting or may be coated or bonded to a substrate (eg, a separator), which may be an ion-conducting membrane. For an interlayer having multiple layers, the different layers may be prepared separately and combined together into a battery.

[0092] The intermediate layer may comprise a conductive medium, such as copper, nickel, stainless steel or conductive carbon. The conductive medium may be a membrane coated on the active layer of the intermediate layer and / or may be a membrane coated on a diaphragm or ion-conducting membrane. The conductive medium may also be a film, a mesh and / or a foam bonded to the active layer of the intermediate layer. The conductive medium may also be particles and / or a conductive polymer incorporated into the active material layer of the intermediate layer.

[0093] The middle layer may include an adhesive for improving the integrity of the middle layer. Suitable adhesives may include, for example, polyvinylidene fluoride (PVDF), polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP), polyethylene oxide (PEO), polytetrafluoroethylene (PTFE), polyurethane, polyacrylonitrile (PAN), polytetraethylene glycol diacrylate, polymethyl methacrylate (PMMA), polymethyl methacrylate, and sodium carboxymethyl cellulose.

[0094] A non-limiting example of an intermediate layer and its characteristics may be described as follows.

[0095] An intermediate layer that can electrochemically inhibit the growth of metal dendrites in a rechargeable battery can include (1) at least one active layer that includes at least one active material that can electrochemically react with ions from a positive electrode, and (2) is conductive. The intermediate layer can be in the form of a single layer or a multilayer. The intermediate layer can be self-supporting or can be bonded to or incorporated into a substrate. The substrate can be a diaphragm that can be configured as an ion-conducting membrane.

[0096] The intermediate layer may include at least one conductive medium, such as copper, nickel, stainless steel, conductive carbon. The conductive medium may be in the form of particles (polymers incorporated into the active material layer of the intermediate layer), a film, a mesh, or a foam. The conductive medium may be self-supporting, may be combined with the active material layer of the intermediate layer, may be a film coated on the active material layer of the intermediate layer, may be a film coated on the substrate. The substrate may be a battery separator, or may be an ion-conducting membrane composed of a separator.

[0097] The intermediate layer may further include at least one adhesive to maintain structural integrity. The adhesive may be polyvinylidene fluoride (PVDF), polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP), polyethylene oxide (PEO), polytetrafluoroethylene (PTFE), polyurethane, polyacrylonitrile (PAN), polytetraethylene glycol diacrylate, polymethyl methacrylate (PMMA), polymethyl methacrylate or sodium carboxymethyl cellulose.

[0098] A non-limiting example of a rechargeable battery having an intermediate layer of the present invention may include a positive electrode, a negative electrode, an electrolyte, two separators or ion-conducting membranes, and the above intermediate layer. The intermediate layer may be disposed between the separators or ion-conducting membranes. In a rechargeable battery, Li+ may be the charge carrier of the battery. During charging, Li + It can be released from the positive electrode and inserted into the negative electrode or reduced to form metallic lithium. During discharge, the process is reversed.

[0099] The active materials for the intermediate layer and the rechargeable battery have been described above. For lithium-ion batteries and lithium metal-based batteries, Si, Sn, Al, Sb, P, graphite, amorphous carbon, SnSb, SnO, SnO2, MnO2, V2O5, TiO2, FeO, Fe3O4, Fe2O3, FeOOH, FePO4, NiCo2O4, SnS, SnS2, Sb2S3, NiS, Ni3S2, CoS2, CuS, FeS2 and / or NiP3 can be used. The active materials may have high capacity and low potential (relative to the lithium deposition potential), such as Si, Sn, Al, Sb, P, amorphous carbon, SnSb, SnO, SnO2, FeO, Fe3O4, Fe2O3, FeOOH, NiCo2O4, SnS, SnS2, Sb2S3, NiS, Ni3S2, CoS2, CuS, FeS2 and NiP3.

[0100] Example 1B: Summary of the properties of the interlayer of the present invention

[0101] This example is used to illustrate that an intermediate layer having an active material can electrochemically suppress lithium dendrite growth. Figure 1A and Figure 1B Schematic diagram of the test cell at two different lithium dendrite growth stages is shown. In the cell, lithium metal is used as the working electrode to serve as a lithium source. Copper is used as the substrate for lithium plating. Three polyethylene (PE) separators are placed between the two electrodes. Two gold conductive layers (Au1 and Au2) are coated on the PE separator and placed between two PE separators, as well as between one separator and the FeOOH active layer, which is also directly coated on Au1 on the PE separator. The FeOOH active layer is 4 mA cm -2 The current is about 3.5 mAh / cm 2 capacity.

[0102] To induce the growth of lithium dendrites, a relatively high current of 4 mA cm was applied. -2 The current is used to perform lithium plating on the copper substrate. When the lithium dendrite grows and reaches Au1 ( Figure 1A ), the FeOOH active layer has electron supply and starts to absorb Li from the lithium source + and is electrochemically reduced. Compared with the state before polarization, the potential of the FeOOH active layer decreases. At the same time, since the potential of the copper electrode is lower than 0V (relative to Li + / Li), so lithium plating on the copper electrode may still continue. If the potential of the copper electrode is higher than 0V (relative to Li + / Li), the plated lithium and lithium dendrites may oxidize, and the lithium dendrites dissolve. Although lithium can still plate on the copper electrode, the potential of the copper electrode will increase. This is due to reduction polarization, as part of the reduction occurring on the FeOOH active layer, the reduction rate on the copper electrode (lithium plating) is reduced, while the total reduction rate is the same (equal to 4 mA cm -2 ). The potential decrease of the FeOOH active layer and the potential increase of the copper electrode lead to the voltage decrease of Au1-Cu (V1). The potential increase of the copper electrode leads to the voltage decrease of Au2-Cu (V2) and Li-Cu (V3). As observed ( Figure 1C ), within the first 95 minutes of lithium plating, the three voltage curves V1, V2 and V3 are smooth. For all three curves, a sharp voltage drop occurs at 95 minutes, indicating that the first dendrites penetrate the underlying PE separator ( Figure 1A ).

[0103] After the dendrites penetrated the underlying PE separator and contacted the Au1 and FeOOH active layers, the lithium dendrites became unstable. This is because the dendrites reacted with FeOOH, and on the other hand, the current flowing through the dendrites might melt the dendrites. This instability of the dendrites caused the potential instability of the Cu electrode and the FeOOH active layer. This caused noise in the V1, V2, and V3 curves, such as Figure 1C However, due to the bridging of dendrites, FeOOH gradually decreases to 0 V (vs. Li + / Li). The potential of the FeOOH active layer reaches 0 V (relative to Li + / Li), the lithium dendrites may start to grow again on the FeOOH active layer. When the dendrites pass through the intermediate PE separator and contact Au2 ( Figure 1B ), V2 becomes approximately 0 V. This occurs at the 143rd minute of the test (48 minutes after the dendrite first shorts Au1). Figure 1C Therefore, as long as the potential of the FeOOH layer is higher than the potential of lithium plating, the growth of lithium dendrites can be stopped in this layer.

[0104] Comparative Example 1: Performance of a battery without an active layer

[0105] In this comparative example, the battery structure is the same as that of Example 1B except that there is no FeOOH active layer. The test conditions are also the same. The schematic diagram and results are shown in FIG. 2A to FIG. 2C It only takes 6 minutes for the dendrite to grow from Au1 to Au2, which is less than 48 minutes for the dendrite with FeOOH active layer in Example 1B. This also confirms the effectiveness of the intermediate layer in suppressing the growth of lithium dendrites.

[0106] Example 2A: Discussion of design and working principle

[0107] A schematic diagram of the design and working principle of the method of the present invention is shown in Figure 3A and Figure 3B Shown in. Figure 3A The structure of a conventional battery is shown. A porous separator is sandwiched between the positive electrode and the negative electrode. Once lithium dendrites grow on the separator, the battery will short-circuit. Figure 3B ), an intermediate layer is placed between the positive and negative electrodes, which is electrically isolated from them by two porous separator layers. The intermediate layer is also porous to allow the electrolyte to be filled for Li + Transfer. Under normal operating conditions, the intermediate layer acts as a part of the separator and no reaction occurs on it. In a battery with such an intermediate layer, when lithium dendrites grow and reach the intermediate layer during charging, electrons are supplied from the original negative electrode to the intermediate layer through the dendrite bridge. Therefore, electrochemical reduction occurs on the intermediate layer. Li from the positive electrode side + The ions react electrochemically with the interlayer instead of forming dendrites that grow toward the positive electrode because the interlayer and Li + The electrochemical reaction potential between the intermediate layer and Li is higher than the potential at which lithium plating occurs. + The electrochemical reactions between ions are thermodynamically favorable.

[0108] To effectively suppress the growth of lithium dendrites, the interlayer can have a sufficiently high lithium storage capacity to consume most or all of the Li + ions. When the capacity of the intermediate layer is equal to or greater than that of Li + The capacity of the electrode from which the ions originally came (e.g., LiCoO2 cathode) is increased, and the intermediate layer is able to absorb all the Li + ions. In order to completely stop the growth of lithium dendrites, the interlayer needs to be able to absorb all the Li + ions. Once the intermediate layer is reduced during charging and absorbs Li + ions, the intermediate layer may be difficult to be oxidized and release Li during the discharge process + This is because during discharge, the lithium dendrites are electrochemically oxidized and dissolved first due to their lower oxidation potential. Due to the loss of the dendrite bridge, there is no electron supply to the intermediate layer. Therefore, when the intermediate layer takes all the Li from the positive electrode (such as LiCoO2) during the short circuit, the lithium dendrites are electrochemically oxidized and dissolved first. + ions, the battery loses all the active Li in the electrode +ion source. Then, the battery becomes non-chargeable and non-dischargeable. This does not mean that the interlayer shortens the cycle life of lithium-ion batteries (LIBs) and that lithium dendrites continue to grow during cycling. Because, on the one hand, LIBs with continuous dendrite growth during cycling may stop working quickly due to the low coulombic efficiency of lithium plating / stripping. Lithium plating causes the growth of dendrites. On the other hand, the growth of lithium dendrites in LIBs may indicate a potential safety problem for the battery, because LIBs are designed to be batteries that do not contain lithium metal during all charge / discharge processes (e.g., short circuits will not be caused by dendrite growth during normal operation). The presence of lithium dendrites can become dangerous and the battery should be avoided at this stage. In short, with or without an interlayer, the life of the LIB ends when lithium dendrites continue to grow during cycling. With an interlayer, the self-immolation of the LIB caused by the internal short circuit of the dendrites can be prevented. Therefore, a significant advantage of the LIB with an interlayer described in this article is that safety is improved. This is particularly important for electric vehicles and grid storage, because a short circuit in a single cell may cause the entire battery pack to catch fire.

[0109] The intermediate layer may consist of or may include a conductive layer. Advantageously, the intermediate layer may include a conductive or non-conductive active material layer. For an intermediate layer having an active material layer with low conductivity or a non-conductive active material layer, a conductive medium may be included to allow the intermediate layer to contact the Li when the dendrite grows and contacts the intermediate layer. + In other words, the intermediate layer with the non-conductive active material layer can be designed to contain a conductive medium to make the intermediate layer conductive. For the conductive intermediate layer, any part that contacts the lithium dendrites can be connected to the Li + The ions undergo electrochemical reactions.

[0110] For practical applications, the conductive layer can be a copper layer with a thickness of several hundred nanometers. A simulation model has been developed to discuss the conductivity requirements of the intermediate layer ( Figure 4 ). This simulation model is discussed in Example 2B below.

[0111] For the interlayer, materials with high specific capacity can be used to reduce the thickness and / or internal resistance caused by the use of the interlayer. Silicon is a striking example in this regard because it has the highest theoretical lithium storage capacity, i.e. 4200 mAh g -1 Capacities approaching or even higher have been reported, as decomposition of the electrolyte adds additional capacity. Using silicon as the active material in the interlayer, 2 to 4 mAh cm -2 capacity loading (typical commercial loading range for LIB electrodes), which may require 0.476 to 0.952 mg cm based on the theoretical capacity. -2If the porosity of the silicon layer is 40%, it corresponds to a thickness of 3.4 to 6.8 μm. When coupled with two commercially available thin separators (e.g., 6 or 7 μm), the total thickness of the separator and the silicon layer is 15.4 to 20.8 μm. This thickness is within the range of thicknesses commonly used in commercial batteries and meets the requirements of various applications.

[0112] To avoid an increase in internal resistance, the interlayer may have enough pores so that a sufficient amount of electrolyte can be filled therein. The porosity of commercial separators is typically 30% to 60%. Therefore, if the porosity of the interlayer is greater than 30%, the ion conductivity of the interlayer can be comparable to that of the commercial separator when filled with electrolyte. The interlayer can easily achieve a porosity of more than 30% due to the presence of gaps between the active particles. In some cases, an additional 2 to 50 μm thick inorganic layer with good ion conductivity between the two electrodes does not impair the performance of the LIB. This is in FIG. 5A to FIG. 5C and FIG. 6 .

[0113] Example 2B: Simulation Model of Current and Potential Distribution in Interlayer with Dendrite Contact

[0114] The conductivity of the interlayer plays a role in the electrochemical reactions that occur over most or all of the interlayer. To investigate this, a simplified model based on circular electrodes was built to simulate the current and potential distribution. Figure 4 As shown, when the dendrite bridges the middle interlayer (circle) during charging, the current (I o ) will flow through the dendrite. Assuming that the electrochemical reaction in each part of the intermediate layer occurs uniformly, the current (IUA) generated per unit area of ​​the intermediate layer due to the electrochemical reaction can be expressed by the following formula (1):

[0115]

[0116] Among them, r edge is the radius of the middle layer.

[0117] The current decreases radially towards 0 A at the edge. Therefore, the current (I) flowing through a circle A in the middle layer (centered at the dendrite point) can be calculated according to the following formula (2):

[0118]

[0119] where r A is the radius of circle A.

[0120] Substituting formula (1) into formula (2), I A It can be expressed by the following formula (3):

[0121]

[0122] The potential is lowest at the point in contact with the dendrite (at the center) compared to any other part of the interlayer and increases radially toward the edge. The voltage (V A ) can be calculated according to formula (4):

[0123]

[0124] Where P A is the electric potential of circle A, P o is the potential at the edge of the dendrite (about 0 V, relative to Li + / Li), r o is the radius of the dendrite, R s is the sheet resistance of the middle layer.

[0125] Substituting formula (3) into formula (4), V A It can be expressed by formula (5):

[0126]

[0127] To estimate the potential increase from the dendrite to the edge and to get a rough idea of ​​the conductivity requirements for the interlayer, an example with the following parameters can be used: R s =2Ωsq -1 ; r o = 10 μm (within the typical dendrite size range), r edge = 2.5 cm (this size is comparable to many types of mobile phone battery electrode sheets), capacity load of the middle layer / electrode: 4 mAh cm -2 (Correspondingly, the total capacity of the sheet is 78.5 mAh, and 0.5C is equal to 39.3 mA.) During charging at a rate of 0.5C, there are dendrites bridging the negative electrode and the middle layer. In the case of complete failure of the negative electrode, the current flowing through the dendrite is 39.3 mA, that is, I o = 39.3 mA. This gives an edge potential of 0.092 V (vs. Li + / Li). This is the highest potential on the middle layer. For low potential materials (such as silicon, aluminum, and tin), this potential is still low enough to allow them to be in contact with the Li in the LIB. + An electrochemical reaction occurs. Therefore, R s =2Ωsq -1 is sufficient for many applications. s Take 6.3Ωsq -1 And r edge Taking 3 mm (the condition of our demonstration experiment), the potential at the edge of the effective lithium plating area is 0.0059 V (relative to Li + / Li), a dendrite short circuit appears in the center. Such a low potential is sufficient for the electrochemical reduction of FeOOH.

[0128] In order to achieve high conductivity / low sheet resistance in practical applications, it may be necessary to add conductive additives to the intermediate layer. It is also feasible to introduce an electrochemically conductive layer in the intermediate layer. For example, the sheet resistance of a metal layer coating (such as copper) with a thickness of 0.05 to 0.2 μm can easily be less than 2Ωsq -1 This thickness of the conductive layer has little effect on the overall thickness of the intermediate layer.

[0129] Example 3A: Materials and Methods (Preparation) Used to Demonstrate the Effectiveness of the Intermediate Layer

[0130] A gold layer of about 60 nm was coated on polyethylene (PE) (EntekGold LP 9 μm) using a JEOL JFC-1600 sputter coating apparatus. FeOOH was prepared as follows.

[0131] Briefly, 10 mL of 0.5 M FeCl3 aqueous solution (Sigma-Aldrich) was added to 70 mL of H2O in a 100 mL plastic bottle with a 0.8 mm pinhole. After shaking for 1 to 2 minutes, the bottle was left to stand in an oven at 100 ° C for 24 hours. The precipitate was collected after cooling, washed several times with deionized water and ethanol, and finally dried overnight at 80 ° C. 31.3 mg of the obtained FeOOH, 5.9 mg of Super P carbon additive (15 wt%) and 2.0 mg of polyvinylidene fluoride (PVDF, 5 wt%) were dispersed in about 3.1 mL of N-methyl-2-pyrrolidone (NMP) and about 7 mL of acetone and ultrasonically treated. The dispersion was vacuum filtered to coat a FeOOH layer (average thickness of about 4 cm) on the gold-coated side of a pure PE diaphragm and a gold-coated diaphragm. The loading density of FeOOH is about 2.5 mg cm -2 .

[0132] In the method for preparing a battery including the intermediate layer of the present invention, the conductive layer (ie, dielectric) may be prepared using a sputtering method. To produce the intermediate layer, methods for preparing electrodes known to those skilled in the art may be used.

[0133] Example 3B: Materials and Methods (Characterization) Used to Demonstrate the Effectiveness of the Present Interlayer

[0134] Field emission scanning electron microscopy (SEM) images were collected on a JEOL JSM-6340F. High-resolution transmission electron microscopy (HRTEM) images were observed using a JEOL JEM 2010 microscope. The thickness of PE and FeOOH-coated PE was measured with a caliper (Mitutoyo Corp., USA) with an accuracy of 1 μm. Electrochemical impedance spectroscopy (EIS) measurements were performed on a Bio-Logic SP-150 potentiostat in the frequency range of 1 MHz to 100 Hz with an AC amplitude of 10 mV to measure the sheet resistance of the gold-plated separators.

[0135] Example 3C: Materials and methods used to demonstrate the effectiveness of the present interlayer (electrochemical measurements)

[0136] The capacity of FeOOH coated on PE was determined in button cells (CR2032) with lithium metal as the counter electrode. The effectiveness of the dual negative electrode approach was demonstrated using cells with glass slides and sealed with Kapton tape in an argon-filled glove box. The detailed cell configuration will be presented together with the results. The electrolyte used for all cells was 1M LiPF6 (MTI Corp.) in ethyl carbonate (EC) / diethyl carbonate (DEC) / dimethyl carbonate (DMC) (4:3:3 by volume). All separators used in this work were PE separators (Entek Gold LP 9μm). All cells were assembled in an argon-filled glove box. Constant current discharge / charge and voltage monitoring were performed using a battery testing equipment (Neware Electronic Co., China).

[0137] Example 3D: Detailed discussion and demonstration of the effectiveness of this intermediate layer

[0138] To demonstrate that the interlayer can effectively prevent the growth of lithium dendrites, a multi-electrode battery was designed and used to conduct Figures 1A to 1C The experiment shown. The demonstration is based on the evaluation of the voltage between different terminals. When the interlayer bridges the lithium dendrite, the interlayer can + ions undergo electrochemical reactions, and as long as the interlayer can be reduced to consume Li + ions can inhibit the growth of lithium dendrites.

[0139] In this demonstration, FeOOH and gold were used as the active material of the intermediate layer and the conductive layer, respectively. Figure 1A and Figure 1B The structures of the test cell with a FeOOH layer at two dendrite growth stages are schematically shown. Figure 1A and Figure 1B The battery configuration and materials have been described in Example 1B and will not be repeated here for the sake of brevity.

[0140] The thickness of the gold coating (Au1 and Au2) was controlled to be about 60 nm. Figure 7 SEM images showing the porous structure of Au-coated PE can be found in . The sheet resistance of Au-coated PE is about 6.3Ωsq -1 ( Figure 8 ). Estimate the sheet resistance (see Figure 4 ) and an effective lithium plating area of ​​6 mm (i.e., the diameter of the lithium in the battery) were sufficient for testing. In addition to conducting electrons, the gold coating was also used to detect the growth of lithium dendrites by monitoring the voltage between the gold layer and the copper electrode.

[0141] The morphology of FeOOH and FeOOH coatings is Fig. 9 , Fig.10 and Fig.11A The FeOOH has a rod-like appearance. The typical thickness of the coated separator is between 37 and 44 μm. The thickness measurement photos of PE and FeOOH-coated PE are shown in Fig. 12A and Fig. 12B The FeOOH layer at 4 mA cm -2 The current density is about 3.5 mAh cm -2 The area capacity ( Fig. 11B ).

[0142] To induce the growth of lithium dendrites, a relatively high current of 4 mA cm was used. -2 Lithium is plated on a copper substrate. This has been described in detail in Example 1B above and will not be repeated here for the sake of brevity. However, when the potential of the copper electrode is higher than 0 V (relative to Li + / Li), the lithium dendrites will dissolve by oxidation, and the reaction on the FeOOH layer will stop due to the loss of dendrite bridges.

[0143] After the dendrites penetrated the bottom PE separator layer and contacted the Au1 and FeOOH layers, the lithium dendrites became unstable. This has been described above and will not be repeated here for the sake of brevity.

[0144] For comparison, the same test was performed on a cell without the FeOOH layer, which was described in Comparative Example 1 above, which confirmed that the present interlayer effectively suppressed lithium dendrite growth.

[0145] In another non-limiting example and as mentioned above, silicon is an attractive material for the intermediate layer for practical applications. The use of FeOOH instead of silicon as the active material in the experiments is only used to demonstrate the working of the invention and not to limit the application of the invention to FeOOH. A voltage drop is used to indicate a short circuit across the separator, but this is difficult to observe for silicon because it is very close to the potential of lithium and it is difficult to observe a voltage drop. This is also because the FeOOH used has a high capacity and a relatively high potential (relative to Li + / Li)( Fig. 11B ), so it is good for testing.

[0146] In conclusion, the present interlayer is an effective method to overcome the lithium dendrite problem in rechargeable lithium batteries. The interlayer acts as a negative electrode only when lithium dendrites grow and the interlayer contacts the lithium dendrites. When lithium dendrites grow and reach the interlayer, Li from the positive electrode + The ions react electrochemically with the interlayer to prevent it from further reducing to form lithium and growing dendrites. Therefore, in LIBs with such an interlayer with sufficient capacity, internal short circuits caused by lithium dendrites are avoided. Self-immolation events of such rechargeable lithium batteries caused by the growth of lithium dendrites are also avoided.

[0147] Example 4: Commercial Applications and Potential Applications

[0148] Since its first commercialization in 1991, lithium-ion batteries (LIBs) have become one of the power sources for mobile phones and laptops due to their high energy density. With the development of large-scale applications such as electric vehicles (EVs) and grid storage, the lithium-ion battery market has experienced faster growth. Despite its widespread use, concerns about the safety of LIBs have been raised and concerns persist since their development began decades ago. In fact, fires and / or explosions related to the use of LIBs have been reported every year over the past decade. These incidents have led to serious safety issues and economic losses.

[0149] It is generally believed that the growth of lithium dendrites is the main cause of LIB safety issues, as lithium plating on a low potential negative electrode (e.g., graphite) can lead to the growth of lithium dendrites, which in turn can cause internal short circuits. The rechargeable battery and interlayer disclosed herein overcome the problem of dendrite growth and solve the key problem of LIB safety. Advantageously, large-scale applications of LIB assemblies involving hundreds or even thousands of cells with zero tolerance for dendrite growth issues are solved. The use of this solution avoids internal short circuits in a single cell, which can cause self-immolation of the entire battery pack, which is more serious than a single cell.

[0150] The rechargeable battery of the present disclosure eliminates dendrite growth and compares favorably with conventional approaches used in LIBs, such as avoiding dendrite growth by using a negative electrode with a higher capacity than the positive electrode or using a high voltage negative electrode, and chemically removing lithium dendrites. These conventional approaches may only be effective to a certain extent, as they may not completely overcome the dendrite growth problem unless energy density is drastically sacrificed, such as using Li4Ti5O 12 Replacing graphite with a negative electrode can reduce it by about 40%. There are also reports of dissolving dendrites by chemical reaction with the active layer. However, this method only delays short circuits, and short circuits still occur eventually. Another conventional solution to the dendrite growth problem involves detecting dendrite growth and internal short circuits, and then isolating the problematic battery. Although this can improve the safety of LIBs, lithium dendrite growth still occurs, causing self-immolation incidents.

[0151] The method of the present invention is different from the conventional scheme. Instead of avoiding, dissolving or detecting dendrites, the method of the present invention relies on the intermediate layer to prevent lithium dendrites from reaching the positive electrode. Only when lithium dendrites grow and contact the intermediate layer, the intermediate layer acts as a negative electrode. The method of the present invention obtains Li from the positive electrode. + ions to avoid lithium plating, thereby stopping the growth of lithium dendrites. With the right materials, the interlayer will not compromise the energy density of the LIB. Therefore, the method of the present invention greatly reduces the self-immolation rate of EVs, mobile phones, laptops and other devices using LIBs. Such advantages make the method of the present invention commercially viable.

[0152] Although the present invention has been shown and described with reference to specific embodiments, it will be appreciated by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the present invention as defined by the appended claims. Therefore, the scope of the present invention is indicated by the appended claims, and is intended to include all changes within the equivalent meaning and scope of the claims.

Claims

1. A rechargeable battery, comprising: negative electrode; positive electrode; an electrolyte in contact with the negative electrode and the positive electrode; as well as an intermediate layer disposed in the electrolyte between the negative electrode and the positive electrode, wherein the intermediate layer is conductive, the negative electrode and the intermediate layer are electrically isolated and thermodynamically configured to allow one or more dendrites to grow in one direction from the negative electrode to the intermediate layer during charging to electrically couple the negative electrode to the intermediate layer, wherein cations present in the electrolyte move from the positive electrode to the negative electrode during charging; The intermediate layer is configured to suppress the growth of the one or more dendrites in a direction from the intermediate layer to the positive electrode by electrochemically reacting one or more dendrites electrically coupled to the negative electrode and the intermediate layer with cations from the positive electrode present in the electrolyte when an electrical coupling is formed between the negative electrode and the intermediate layer.

2. The rechargeable battery according to claim 1, wherein: The intermediate layer is configured to include one or more active materials.

3. The rechargeable battery according to claim 2, wherein: The one or more active materials include Si, Sn, Al, Sb, P, graphite, amorphous carbon, SnSb, SnO, SnO2, MnO2, V2O5, TiO2, FeO, Fe3O4, Fe2O3, FeOOH, FePO4, NiCo2O4, SnS, SnS2, Sb2S3, NiS, Ni3S2, CoS2, CuS, FeS2, NiP3 or a combination thereof.

4. The rechargeable battery according to claim 2 or 3, wherein: The intermediate layer receives electrons from the negative electrode for one or more active materials included in the intermediate layer to electrochemically react with the cations when the one or more dendrites contact the intermediate layer.

5. The rechargeable battery according to claim 1, wherein: The intermediate layer includes a non-conductive active material layer.

6. The rechargeable battery according to claim 1, wherein: The intermediate layer is porous.

7. The rechargeable battery according to claim 1, wherein: The intermediate layer is non-porous.

8. The rechargeable battery according to claim 1, wherein The intermediate layer includes at least one conductive medium, and the conductive medium includes copper, gold, nickel, stainless steel, conductive carbon, conductive polymer or a combination thereof.

9. The rechargeable battery according to claim 1, wherein: The intermediate layer is electrically isolated from the negative electrode and / or the positive electrode by a separator located between (i) the negative electrode and the intermediate layer and / or (ii) the positive electrode and the intermediate layer.

10. The rechargeable battery according to claim 9, wherein: The diaphragm is designed as an ion-conducting membrane.

11. The rechargeable battery according to claim 9, wherein: The separator includes polyethylene, polypropylene or a combination thereof.

12. The rechargeable battery according to claim 9, wherein: The separator serves as a substrate provided with the intermediate layer.

13. The rechargeable battery according to claim 1, wherein: The intermediate layer is configured to include an adhesive.

14. The rechargeable battery according to claim 13, wherein: The binder includes polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyethylene oxide, polytetrafluoroethylene, polyurethane, polyacrylonitrile, polyethylene glycol diacrylate, polymethyl methacrylate, sodium carboxymethyl cellulose or a combination thereof.

15. The rechargeable battery according to claim 1, wherein The cations include lithium ions.

16. The rechargeable battery according to claim 1, wherein: The rechargeable battery is operable to have: (i) the potential of the intermediate layer being maintained higher than that of Li during charging of the rechargeable battery; + / Li potential; and (ii) upon discharging the rechargeable battery, the one or more dendrites retreat from the intermediate layer toward the negative electrode.

17. The rechargeable battery according to claim 1, wherein: The intermediate layer is configured to include a thickness of 2 mm or less.

18. An intermediate layer that can be disposed between a negative electrode and a positive electrode in an electrolyte of a rechargeable battery, wherein: The intermediate layer is conductive, the negative electrode and the intermediate layer are electrically isolated and thermodynamically configured to allow one or more dendrites to grow in one direction from the negative electrode to the intermediate layer during charging to electrically couple the negative electrode to the intermediate layer, wherein cations present in the electrolyte move from the positive electrode to the negative electrode during charging; The intermediate layer is configured to suppress the growth of the one or more dendrites in a direction from the intermediate layer to the positive electrode by electrochemically reacting one or more dendrites electrically coupled to the negative electrode and the intermediate layer with cations from the positive electrode present in the electrolyte when an electrical coupling is formed between the negative electrode and the intermediate layer.

19. The intermediate layer according to claim 18, wherein The intermediate layer is configured to include one or more active materials.

20. The intermediate layer according to claim 19, wherein The one or more active materials include Si, Sn, Al, Sb, P, graphite, amorphous carbon, SnSb, SnO, SnO2, MnO2, V2O5, TiO2, FeO, Fe3O4, Fe2O3, FeOOH, FePO4, NiCo2O4, SnS, SnS2, Sb2S3, NiS, Ni3S2, CoS2, CuS, FeS2, NiP3 or a combination thereof.

21. The intermediate layer according to claim 19 or 20, wherein The intermediate layer receives electrons from the negative electrode for one or more active materials included in the intermediate layer to electrochemically react with the cations when the one or more dendrites contact the intermediate layer.

22. The intermediate layer according to claim 18, wherein The intermediate layer includes a non-conductive active material layer.

23. The intermediate layer according to claim 18, wherein The intermediate layer is porous.

24. The intermediate layer according to claim 18, wherein The intermediate layer is non-porous.

25. The intermediate layer according to claim 18, wherein The intermediate layer includes at least one conductive medium, and the conductive medium includes copper, gold, nickel, stainless steel, conductive carbon, conductive polymer or a combination thereof.

26. The intermediate layer according to claim 18, wherein The intermediate layer is a self-supporting layer or is disposed on a substrate.

27. The intermediate layer according to claim 26, wherein The substrate includes a membrane that can be configured as an ion conducting membrane.

28. The intermediate layer according to claim 27, wherein The separator includes polyethylene, polypropylene or a combination thereof.

29. The intermediate layer according to claim 18, wherein The intermediate layer includes an adhesive.

30. The intermediate layer according to claim 29, wherein The binder includes polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyethylene oxide, polytetrafluoroethylene, polyurethane, polyacrylonitrile, polyethylene glycol diacrylate, polymethyl methacrylate, sodium carboxymethyl cellulose or a combination thereof.

31. The intermediate layer according to claim 18, wherein The cations include lithium ions.

32. The intermediate layer according to claim 18, wherein The intermediate layer is configured to include a thickness of 2 mm or less.

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