Carbon-coated solid-state electrolyte, battery, and electric device

Abstract

The present application provides a carbon-coated solid-state electrolyte, a battery, and an electric device. The carbon-coated solid-state electrolyte comprises an electrolyte core and a carbon coating layer coated on the surface of the electrolyte core. An X-ray photoelectron spectroscopy test result of the carbon coating layer shows the following characteristics: a carbon element exhibits a first peak position corresponding to sp3 hybridization and a second peak position corresponding to sp2 hybridization, and the ratio of the intensity of the first peak position to the intensity of the second peak position is greater than or equal to 0.1.

Description

Carbon-coated solid-state electrolyte, battery and electric device

[0001] This application claims priority to the Chinese patent application No. 202411298726.8, filed on September 18, 2024, and entitled "Carbon-coated solid-state electrolyte, battery and electric device", the entire content of which is incorporated herein by reference. TECHNICAL FIELD

[0002] The present application relates to the technical field of batteries, in particular to a carbon-coated solid-state electrolyte, a battery and an electric device. BACKGROUND

[0003] A battery is a device capable of storing and releasing electrical energy. Lithium ion batteries are the most widely used battery system in commercial applications. In traditional lithium ion batteries, liquid electrolyte is usually used. Although it can provide high ionic conductivity, it also causes electrode side reactions and poor thermal stability, resulting in poor safety performance of the battery. The introduction of solid-state electrolyte not only improves the safety performance of the battery, but also optimizes the overall performance of the battery, which has high application potential.

[0004] However, the current solid-state electrolyte still has the problems of easy side reaction with electrode materials and low ionic conductivity, which limits the further application of solid-state electrolyte. SUMMARY

[0005] Therefore, it is necessary to provide a carbon-coated solid-state electrolyte which can effectively improve the ionic conductivity and inhibit the side reaction with the electrode material.

[0006] According to some embodiments of the present application, a carbon-coated solid-state electrolyte is provided, which comprises an electrolyte core and a carbon coating layer coated on the surface of the electrolyte core, and the X-ray photoelectron spectroscopy test result of the carbon coating layer has the following characteristics: the carbon element has a first peak position corresponding to sp3 hybridization and a second peak position corresponding to sp2 hybridization, and the ratio of the intensity of the first peak position to the intensity of the second peak position is greater than or equal to 0.1.

[0007] In some embodiments of the present application, in the X-ray photoelectron spectroscopy test result of the carbon coating layer, the carbon element has a composite peak formed by superimposing the first peak position and the second peak position between 284eV and 287eV, and after peak separation processing, the composite peak forms a first peak position between 284eV and 285eV and a second peak position between 285eV and 286eV, respectively.

[0008] In some embodiments of the present application, the carbon coating layer further comprises oxygen elements, and the X-ray photoelectron spectroscopy test result of the carbon coating layer further has the following characteristics: the oxygen elements have peak positions between 530eV-532eV and 528eV-530eV.

[0009] In some embodiments of the present application, the thickness of the carbon coating layer is 1nm-100nm.

[0010] In some embodiments of the present application, the material of the electrolyte core comprises one or more of oxide solid electrolyte, halide solid electrolyte and polymer solid electrolyte.

[0011] The oxide solid electrolyte is selected from one or more of lithium aluminum titanium phosphate, lithium aluminum germanium phosphate, lithium lanthanum zirconium oxide and lithium phosphorus oxynitride.

[0012] The halide solid electrolyte is selected from one or more of lithium indium chloride, lithium yttrium chloride and lithium zirconium chloride.

[0013] In some embodiments of the present application, the particle size of the electrolyte core is 100nm-100μm.

[0014] The present application also provides a preparation method of the above-mentioned solid electrolyte, which comprises the step of preparing a carbon coating layer on the surface of the electrolyte core.

[0015] The step of preparing a carbon coating layer comprises: mixing a carbon source precursor with the electrolyte core, and performing calcination by microwave heating treatment in a protective gas to form a carbon coating layer on the surface of the electrolyte core; or,

[0016] The step of preparing a carbon coating layer comprises: placing the electrolyte core in a deposition chamber, introducing a carbon source gas into the deposition chamber, and using direct photochemical vapor deposition or plasma enhanced chemical vapor deposition to deposit a carbon coating layer on the surface of the electrolyte core.

[0017] The present application also provides a battery comprising the carbon-coated solid electrolyte according to any one of the above-mentioned embodiments.

[0018] In some embodiments of the present application, the positive electrode of the battery comprises a positive electrode active layer, and the carbon-coated solid electrolyte is arranged in the positive electrode active layer; or,

[0019] The positive electrode of the battery comprises a positive electrode active layer and an ion-conducting layer arranged in a stack, and the carbon-coated solid electrolyte is arranged in the ion-conducting layer; or,

[0020] The battery comprises a positive electrode, a negative electrode and a separator arranged between the positive electrode and the negative electrode, and the carbon-coated solid electrolyte is arranged on the side of the separator close to the positive electrode.

[0021] In some embodiments of the present application, the battery is a lithium ion battery, a solid-state battery or a semi-solid battery.

[0022] The present application also provides a battery, which comprises a functional body and a battery as described in any of the above embodiments, and the battery is used to supply power for the functional body.

[0023] The carbon coating layer contains not only carbon atoms bonded in sp2 hybridization, but also carbon atoms bonded in sp3 hybridization. Compared with sp2 hybridization, the structure formed by sp3 hybridization is more solid, and the effect of sp3 hybridization on promoting ion conduction is more obvious. The carbon coating layer with a ratio of the intensity of the first peak to the intensity of the second peak ≥0.1 can effectively avoid the deterioration caused by the contact between the electrolyte core and the electrode active material, and can also improve the ionic conductivity of the solid-state electrolyte.

[0024] Experiments have verified that the modification of the positive electrode part of the battery by using the carbon-coated solid-state electrolyte can effectively improve the charge-discharge specific capacity and the cycle stability of the battery.

[0025] The above description is only a summary of the technical solutions of the present application. In order to more clearly understand the technical means of the present application, and to implement the content of the description, the following will describe the preferred embodiments of the present application in detail with the help of the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0026] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiment description. Obviously, the drawings in the following description are only some embodiments of the present application, and those skilled in the art can obtain other drawings of embodiments according to these drawings without creating any creative labor.

[0027] Fig. 1 is a schematic diagram of the steps of a preparation method of a carbon-coated solid-state electrolyte;

[0028] Fig. 2 is a schematic diagram of the morphology of the carbon-coated solid-state electrolyte in Example 1 observed by transmission electron microscopy;

[0029] Fig. 3 is a test result graph of the X-ray photoelectron spectroscopy of the carbon-coated solid-state electrolyte in Example 1 and the corresponding processed curve, wherein the left graph is the test result graph, and the right graph is the curve after fitting and peak separation processing of the left graph;

[0030] Fig. 4 is a test result graph of the X-ray photoelectron spectroscopy of the carbon-coated solid-state electrolyte in Comparative Example 1 and the corresponding processed curve, wherein the left graph is the test result graph, and the right graph is the curve after fitting processing of the left graph. DETAILED DESCRIPTION

[0031] For the purposes of the present document, a full description of the embodiments of the present document will be presented. Preferred embodiments of the present document are presented herein. However, the present document can be realized in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that this document will be thorough and complete, and fully convey the scope of the present document to those skilled in the art.

[0032] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this document belongs. The terminology used in the description of the present document herein is for describing particular embodiments only and is not intended to be limiting of the present document.

[0033] It will be understood that when an element or layer is referred to as being "on" or "adjacent" or "connected" or "coupled" to another element or layer, it can be directly on, adjacent, connected or coupled to the other element or layer or one or more intervening elements or layers can also be present. In contrast, when an element is referred to as being "directly on," "directly adjacent," "directly connected" or "directly coupled" to another element or layer, there are no intervening elements or layers present. It will be understood that, although the terms first, second, third, etc. can be used herein to describe various elements, components, regions, layers and / or sections, these elements, components, regions, layers and / or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another element, component, region, layer or section.

[0034] Spatially relative terms, such as "beneath", "below", "lower", "under", "above", "upper" and the like, can be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientations depicted in the figures. For example, if the device in the figures is turned over, elements described as "below" or "beneath" other elements or features would then be oriented "above" or "over" the other elements or features. Thus, the exemplary term "below" can encompass both an orientation of above and below. The device can be otherwise oriented (e.g., rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

[0035] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting thereof. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and / or "comprising", when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. As used herein the term "and / or" includes any and all combinations of associated items.

[0036] The material of the carbon coating layer for coating the solid-state electrolyte in the conventional technology is generally amorphous carbon material and / or graphitized carbon material, wherein the carbon atoms in the graphitized carbon material are bonded in sp2 hybridization manner, and the material shows a peak corresponding to sp2 hybridization in the X-ray photoelectron spectroscopy test result. The graphitized carbon material has high conductivity, which is beneficial to promote the conduction of electrons.

[0037] In a first aspect, the present application provides a carbon-coated solid-state electrolyte, which comprises an electrolyte core and a carbon coating layer coated on the surface of the electrolyte core, and the carbon coating layer has the following characteristics in the X-ray photoelectron spectroscopy test result: the carbon element has a first peak position corresponding to sp3 hybridization and a second peak position corresponding to sp2 hybridization, and the ratio of the intensity of the first peak position to the intensity of the second peak position is ≥0.1.

[0038] The carbon coating layer contains not only carbon atoms bonded in sp2 hybridization manner, but also carbon atoms bonded in sp3 hybridization manner. Compared with the carbon atoms bonded in sp2 hybridization manner, the structure formed by the carbon atoms bonded in sp3 hybridization manner is more solid, and the carbon atoms bonded in sp3 hybridization manner are more obvious in promoting ion conduction. The carbon coating layer with the ratio of the intensity of the first peak position to the intensity of the second peak position ≥0.1 can effectively avoid the deterioration caused by the contact between the electrolyte core and the electrode active material, and also can improve the ionic conductivity of the solid-state electrolyte.

[0039] It has been verified through experiments that the modification of the positive electrode part in the battery by using the carbon-coated solid-state electrolyte can effectively improve the charge-discharge specific capacity and the cycle stability of the battery.

[0040] It can be understood that the actual positions of the first peak and the second peak corresponding to sp3 hybridization and sp2 hybridization in the X-ray photoelectron spectroscopy test results are related to the overall structure and components of the material, which makes the actual positions of the first peak and the second peak different in different carbon coating layers. In addition, the first peak and the second peak may also form a composite peak due to partial overlap, but the skilled person can analyze the hybridization state corresponding to each peak from the X-ray photoelectron spectroscopy test results by combining the general knowledge in the art and peak separation processing and other technical means.

[0041] As an example of this embodiment, the ratio of the intensity of the first peak to the intensity of the second peak can be 0.1, 0.3, 0.5, 1, 2, 3, 5, 7, 10, 20, 30, 50, 100, or the ratio of the intensity of the first peak to the intensity of the second peak can also be between any two of the above values.

[0042] It can be understood that the ratio of the intensity of the first peak to the intensity of the second peak in this document can not have an upper limit, for example, when the second peak is essentially absent in the carbon coating layer, the ratio of the intensity can be infinite.

[0043] As an example of this embodiment, in the X-ray photoelectron spectroscopy test results of the carbon coating layer, the carbon element has a composite peak between 284 eV and 287 eV formed by superimposing the first peak and the second peak, and after peak separation processing, the composite peak forms a first peak between 284 eV and 285 eV and a second peak between 285 eV and 286 eV, respectively.

[0044] As an example of this embodiment, the carbon coating layer further includes oxygen elements. Further, the X-ray photoelectron spectroscopy test results of the carbon coating layer further have the following characteristics: the oxygen element has a peak between 530 eV and 532 eV and between 528 eV and 530 eV. During the research, it was found that when the carbon coating layer exists and the oxygen element has a peak between 530 eV and 532 eV and between 528 eV and 530 eV, the carbon-coated solid electrolyte has better ion conductivity.

[0045] As an example of this embodiment, the thickness of the carbon coating layer is 1 nm to 100 nm. The carbon coating layer in this thickness range can take into account better protection and promote ion conduction. When the thickness is too thick, the thick carbon coating layer may block the normal transmission of ions.

[0046] As an example of this embodiment, the thickness of the carbon coating layer is 1 nm to 20 nm. For example, the thickness of the carbon coating layer can be 1 nm, 2 nm, 3 nm, 4 nm, 5 nm, 7 nm, 10 nm, 12 nm, 15 nm, 17 nm, or 20 nm, or the thickness of the carbon coating layer can be between any two of the above thicknesses.

[0047] As an example of this embodiment, the material of the electrolyte core includes one or more of oxide solid electrolytes, halide solid electrolytes, and polymer solid electrolytes.

[0048] In this example, the oxide solid electrolyte is selected from lithium titanium aluminum phosphate (Li... 1.5 Al 0.5 Ti 1.5 (PO4)), lithium aluminum germanium phosphate (Li) 1.5 Al 0.5 Ge 1.5 (PO4)), Lithium lanthanum zirconium oxide (Li7La3Zr2O) 12 One or more of lithium phosphorus oxynitrate (LiPON).

[0049] In this example, the halide solid electrolyte is selected from one or more of lithium indium chloride (Li3InCl6), lithium yttrium chloride (Li3YCl6), and lithium zirconium chloride (Li2ZrCl6).

[0050] As an example of this embodiment, the particle size of the electrolyte core is 100 nm to 100 μm. For example, the particle size of the electrolyte core can be 100 nm, 500 nm, 1 μm, 5 μm, 10 μm, 15 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, or 100 μm, or the particle size of the electrolyte core can be between any two of the above particle sizes.

[0051] Secondly, this application also provides a method for preparing a carbon-coated solid electrolyte, which includes the step of forming a carbon coating layer on the surface of the electrolyte core.

[0052] Figure 1 is a schematic diagram of the preparation method of a carbon-coated solid electrolyte. Referring to Figure 1, the preparation method of the carbon-coated solid electrolyte includes the following steps S1 to S2.

[0053] Step S1: Provide the electrolyte core.

[0054] As some examples of this embodiment, the electrolyte core material includes one or more of oxide solid electrolytes, halide solid electrolytes, and polymer solid electrolytes.

[0055] In this example, the oxide solid electrolyte is selected from lithium titanium aluminum phosphate (Li...1.5 Al 0.5 Ti 1.5 (PO4)), lithium aluminum germanium phosphate (Li) 1.5 Al 0.5 Ge 1.5 (PO4)), Lithium lanthanum zirconium oxide (Li7La3Zr2O) 12 One or more of lithium phosphorus oxynitrate (LiPON).

[0056] In this example, the halide solid electrolyte is selected from one or more of lithium indium chloride (Li3InCl6), lithium yttrium chloride (Li3YCl6), and lithium zirconium chloride (Li2ZrCl6).

[0057] Step S2: A carbon coating layer is formed on the surface of the electrolyte core.

[0058] As an example of this embodiment, the steps for preparing the carbon coating layer include: mixing a carbon source precursor with an electrolyte core, and calcining the mixture using microwave heating in a protective gas to form a carbon coating layer on the surface of the electrolyte core. Compared to conventional heat conduction heating, calcining the carbon source precursor by directly heating it with microwaves allows the precursor to transform into sp3 hybridized carbon elements, thus giving the carbon elements in the carbon coating layer an sp3 hybridized composition.

[0059] As an example of this embodiment, the protective gas should be selected from gases that do not react with the carbon source precursor and the electrolyte core. In some examples, the protective gas is selected from one or more of argon and nitrogen.

[0060] As an example of this embodiment, during the calcination process using microwave heating, the mixed materials can be heated to 180°C–1500°C. It is understood that the heating temperature may vary depending on the different carbon source precursors, and should be determined based on the desired structure of the carbon coating layer. The heating temperature can be controlled by adjusting the microwave power.

[0061] As an optional example of this embodiment, the mixed material can be controlled to be microwave-heated to 500°C to 700°C. As some examples, the mixed material can be controlled to be microwave-heated to 500°C, 520°C, 550°C, 570°C, 600°C, 620°C, 650°C, 670°C, or 700°C, or the mixed material can be controlled to be microwave-heated to any two of the above temperatures.

[0062] As an example of this embodiment, the mixed material can be controlled to be microwave heated for 2h-8h. For example, the mixed material can be controlled to be microwave heated for 2h, 3h, 4h, 5h, 6h, 7h, 8h, or the mixed material can be controlled to be microwave heated for a time between any two of the above times.

[0063] It can be understood that by controlling the temperature and the heating time of the microwave heating, the intensity ratio of the first peak and the second peak in the carbon coating layer formed can be correspondingly controlled.

[0064] As an example of this embodiment, the mass ratio of the carbon source precursor and the electrolyte core can be (1:10)-(10:1).

[0065] As an example of this embodiment, the carbon source precursor includes one or more of phenolic resin, furfuryl resin, epoxy resin, urea-formaldehyde resin, pitch, citric acid, glucose, sucrose, polyvinyl chloride, and polyvinyl butyral.

[0066] As another example of this embodiment, the step of forming the carbon coating layer includes: placing the electrolyte core in a deposition chamber, introducing a carbon source gas into the deposition chamber, and using direct photochemical vapor deposition or plasma-enhanced chemical vapor deposition to deposit a carbon coating layer on the surface of the electrolyte core. Compared with the usual thermal decomposition deposition method, the deposition method using direct photochemical vapor deposition or plasma-enhanced chemical vapor deposition can make the carbon atoms produced by decomposition form sp3 hybrid bonds, so that the carbon elements in the carbon coating layer have sp3 hybrid components.

[0067] It can be understood that by controlling the light intensity in the photochemical vapor deposition process and the radio frequency power in the plasma-enhanced chemical vapor deposition process, the intensity ratio of the first peak and the second peak in the carbon coating layer formed can be correspondingly controlled.

[0068] As an example of this embodiment, a protective gas is also introduced into the deposition chamber. The protective gas should be selected from a gas that does not react with the carbon source precursor and the electrolyte core. In some examples, the protective gas is selected from one or more of argon and nitrogen.

[0069] As an example of this embodiment, during the deposition process, the environmental temperature in the deposition chamber can be controlled to be 180°C-1500°C.

[0070] As an example of this embodiment, the ambient temperature in the deposition chamber can be controlled to be 500-700℃. As some examples, the ambient temperature in the deposition chamber can be controlled to be 500℃, 520℃, 550℃, 570℃, 600℃, 620℃, 650℃, 670℃, 700℃, or the ambient temperature in the deposition chamber can also be controlled to be between any two of the above temperatures.

[0071] As an example of this embodiment, the deposition time can be controlled to be 1-10h. For example, the deposition time can be controlled to be 1h, 2h, 3h, 4h, 5h, 6h, 7h, 8h, 10h, or the deposition time can also be controlled to be between any two of the above times.

[0072] As an example of this embodiment, the carbon source gas includes one or more of acetylene, ethylene, methane, ethane, propane and n-butane.

[0073] As an example of this embodiment, the flow rate of the carbon source gas introduced into the deposition chamber can be 0.1-10L / min.

[0074] In a third aspect, the present application also provides a battery. The battery includes the solid electrolyte in the above embodiments. It can be understood that the battery should include a positive electrode and a negative electrode. The solid electrolyte can be disposed inside the positive electrode, inside the negative electrode or between the positive electrode and the negative electrode.

[0075] As an example of this embodiment, the positive electrode of the battery includes a positive electrode active layer, and the carbon-coated solid electrolyte is disposed in the positive electrode active layer.

[0076] As another example of this embodiment, the positive electrode of the battery includes a positive electrode active layer and an ion-conducting layer which are stacked, and the carbon-coated solid electrolyte is disposed in the ion-conducting layer.

[0077] As yet another example of this embodiment, the battery includes a positive electrode, a negative electrode and a separator disposed between the positive electrode and the negative electrode, and the carbon-coated solid electrolyte is disposed on the side of the separator close to the positive electrode.

[0078] It can be understood that the carbon-coated solid electrolyte includes a carbon coating layer, which has a relatively strong and stable structure, and is conducive to avoiding direct contact between the solid electrolyte and the positive active material in the positive electrode active layer, thereby ensuring the material stability of the electrolyte core. At the same time, the carbon-coated solid electrolyte can also improve the ion conductivity of the positive electrode active layer.

[0079] As an example of this embodiment, the positive electrode can include a positive electrode tab. The positive electrode tab includes a positive electrode current collector and a positive electrode active layer.

[0080] In some examples, the positive active layer includes a positive active material. The positive active material is selected from one or more of lithium cobaltate, lithium nickelate, lithium manganate, a layered ternary positive active material, a spinel lithium nickel manganate, lithium iron phosphate, lithium iron manganese phosphate, lithium manganese phosphate, and lithium cobalt phosphate.

[0081] In some examples, the positive active layer can further include one or more of a conductive agent and a binder.

[0082] In the positive active layer, the conductive agent can be selected from one or more of conductive carbon black, carbon nanotubes, graphene, and carbon nanofibers.

[0083] In the positive active layer, the binder can be selected from one or more of polyvinylpyrrolidone, polyvinylidene fluoride, polyethylene oxide, polytetrafluoroethylene, carboxymethyl cellulose, and a copolymer of styrene and butadiene.

[0084] As an example of this embodiment, the negative electrode can include a negative electrode tab. The negative electrode tab includes a negative current collector and a negative active layer disposed on the negative current collector, the negative active layer including a negative active material.

[0085] In some examples, the negative active material includes one or more of graphite, silicon, silicon-carbon, metallic lithium, and lithium titanate. Additionally, a silicon-based material can also be included. The silicon-based material can include one or more of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. In some specific examples, the silicon-based material takes the form of silicon-oxygen material or pre-lithiated silicon-oxygen particles.

[0086] In some examples, the negative active layer can further include one or more of a conductive agent and a binder.

[0087] In the negative active layer, the conductive agent can be selected from one or more of conductive carbon black, carbon nanotubes, graphene, and carbon nanofibers.

[0088] In the negative active layer, the binder can be selected from one or more of polyvinylpyrrolidone, polyvinylidene fluoride, polyethylene oxide, polytetrafluoroethylene, carboxymethyl cellulose, and a copolymer of styrene and butadiene.

[0089] In a fourth aspect, the present application also provides a power consuming device, the power consuming device including a functional body and a battery as in any of the above embodiments, the battery being configured to supply power to the functional body.

[0090] As an example of this embodiment, the power consuming device can be a mobile phone, a notebook computer, a smart watch, or an electric vehicle.

[0091] In order to facilitate the understanding of the specific embodiments and beneficial effects of the present application, the present application also provides the following more specific examples and comparative examples. Through the description of the examples and comparative examples, the beneficial effects of the present application will also be more obvious.

[0092] Example 1

[0093] Preparation of carbon-coated solid electrolyte: titanium aluminum lithium phosphate with a particle size of 1 μm was used as the electrolyte core, which was stirred and mixed uniformly with sucrose according to a mass ratio of 10:1 to form a mixed material. The mixed material was transferred to a microwave sintering chamber, an argon atmosphere was maintained in the microwave sintering chamber, and the mixed material was heated to 650 ℃ for calcination for 2 h, and then cooled to room temperature to form a carbon-coated solid electrolyte material.

[0094] Preparation of positive electrode sheet: carbon-coated solid electrolyte, ternary positive electrode, polyvinylidene fluoride and SuperP were uniformly mixed according to a mass ratio of 5:90:3:2 and dispersed in N-methyl pyrrolidone to form a slurry, and the slurry was coated on the surface of an aluminum foil and dried to form a positive electrode sheet.

[0095] Preparation of electrolyte: a mixed solvent of EC, DMC and FEC was used, wherein the volume ratio of EC, DMC and FEC was 4.8:4.8:0.4, and lithium hexafluorophosphate was dissolved in the mixed solvent, and the molar concentration of lithium hexafluorophosphate was 1 mol / L.

[0096] Preparation of battery: the above positive electrode sheet was paired with a lithium sheet to form a half-cell, and Celgard2300 separator film was interposed between the positive electrode sheet and the lithium sheet.

[0097] Example 2

[0098] Example 2 and Example 1 only differ in the preparation process of the carbon-coated solid electrolyte. The preparation process of the carbon-coated solid electrolyte in Example 2 is as follows: the carbon-coated solid electrolyte is placed in a direct photochemical vapor deposition chamber, ethyne with a flow rate of 1 L / min is introduced as a carbon source gas, the temperature of the deposition chamber is controlled at 700 ℃, and the deposition time is 4 h. After the end, it is cooled to room temperature to form a carbon-coated solid electrolyte material.

[0099] Example 3

[0100] Example 3 and Example 1 only differ in the preparation process of the carbon-coated solid electrolyte. The preparation process of the carbon-coated solid electrolyte in Example 3 is as follows: the carbon-coated solid electrolyte is placed in a plasma-enhanced chemical vapor deposition chamber, ethyne with a flow rate of 1 L / min is introduced as a carbon source gas, the temperature of the deposition chamber is controlled at 700 ℃, and the deposition time is 4 h. After the end, it is cooled to room temperature to form a carbon-coated solid electrolyte material.

[0101] Example 4

[0102] Example 4 differs from Example 1 only in that lithium indium chloride is used as the electrolyte core.

[0103] Example 5

[0104] Example 5 differs from Example 1 only in the preparation process of the positive electrode sheet.

[0105] The preparation process of the positive electrode sheet in Example 5 is as follows: lithium iron phosphate, polyvinylidene fluoride and SuperP are uniformly mixed in a mass ratio of 90:3:2 and dispersed in N-methyl pyrrolidone to form a slurry, the slurry is coated on the surface of an aluminum foil and dried to form a positive active layer. Then the carbon-coated solid electrolyte is dispersed in N-methyl pyrrolidone to form a slurry, which is coated on the surface of the positive active layer and dried to form a positive electrode sheet.

[0106] Example 6

[0107] Example 6 differs from Example 1 only in the preparation process of the positive electrode sheet and the battery.

[0108] The preparation process of the positive electrode sheet in Example 6 is as follows: lithium iron phosphate, polyvinylidene fluoride and SuperP are uniformly mixed in a mass ratio of 90:3:2 and dispersed in N-methyl pyrrolidone to form a slurry, the slurry is coated on the surface of an aluminum foil and dried to form a positive electrode sheet.

[0109] The preparation process of the positive electrode sheet in Example 6 is as follows: the carbon-coated solid electrolyte is dispersed in N-methyl pyrrolidone to form a slurry, which is coated on the surface of Celgard 2300 separator film close to the positive electrode and dried, and then the separator film, the above-mentioned positive electrode sheet and lithium sheet are paired and assembled to form a half-cell.

[0110] Comparative Example 1

[0111] Comparative Example 1 differs from Example 1 only in that no carbon-coated solid electrolyte is prepared in Comparative Example 1, and the solid electrolyte is used instead of the carbon-coated solid electrolyte in Example 1 in the preparation of the positive electrode sheet.

[0112] Comparative Example 2

[0113] Comparative Example 2 differs from Example 1 only in the preparation process of the carbon-coated solid electrolyte. In Comparative Example 2, instead of using microwave radiation heating, a resistance furnace is used for heat conduction heating when preparing the carbon-coated solid electrolyte.

[0114] Comparative Example 3

[0115] The difference between Comparative Example 3 and Example 2 is only in the preparation process of the carbon-coated solid electrolyte. In Comparative Example 3, a conventional tube furnace is used for deposition in the preparation of the carbon-coated solid electrolyte, instead of the direct photochemical vapor deposition chamber.

[0116] Test 1: The morphology of the carbon-coated solid electrolyte in Example 1 is observed by transmission electron microscopy, and the morphology diagram of the carbon-coated solid electrolyte can be seen in Figure 2.

[0117] Test 2: The carbon-coated solid electrolytes in Example 1 and Comparative Example 1 are respectively subjected to X-ray photoelectron spectroscopy test, and the results can be seen in Figures 3-4. Figure 3 is the X-ray photoelectron spectroscopy test result diagram and the corresponding processed curve of the carbon-coated solid electrolyte in Example 1, wherein the left graph is the test result diagram, and the right graph is the curve after fitting and peak separation processing. Figure 4 is the X-ray photoelectron spectroscopy test result diagram and the corresponding processed curve of the carbon-coated solid electrolyte in Comparative Example 1, wherein the left graph is the test result diagram, and the right graph is the curve after fitting processing.

[0118] Referring to Figure 2, according to the observation results of the transmission electron microscope, it can be determined that there is an obvious carbon coating layer on the surface of the product prepared in Example 1, and the thickness of the carbon coating layer is below 10 nm, specifically about 3 nm.

[0119] Further, referring to Figure 3, the abscissa in Figure 3 represents the binding energy, and the ordinate represents the intensity. After peak separation processing of the X-ray photoelectron spectroscopy test results of Example 1, there is a first peak between 284eV and 285eV, and the intensity of the first peak is denoted as C1. There is a second peak between 283eV and 284eV, and the intensity of the second peak is denoted as C2. The first peak corresponds to sp3 hybridized carbon elements, and the second peak corresponds to sp2 hybridized carbon elements. Obviously, the ratio of the intensity C1 of the first peak to the intensity C2 of the second peak is about 1.4. This indicates that there are more sp3 hybridized carbon elements in the carbon coating layer prepared in the preparation process of Example 1.

[0120] Referring to Figure 4, the X-ray photoelectron spectroscopy test results of Comparative Example 1 only show one peak, which corresponds to sp2 hybridized carbon elements. This indicates that there are only sp2 hybridized carbon elements in the carbon coating layer prepared in the preparation process of Comparative Example 1, and there are basically no sp3 hybridized carbon elements.

[0121] Test 3: The batteries of the above examples and comparative examples are subjected to charge-discharge cycle test, and the test results can be seen in Table 1.

[0122] Table 1

[0123] Referring to Table 1, the Comparative Example 1 does not prepare a carbon coating layer on the surface of the electrolyte, and directly adds the solid electrolyte into the positive electrode sheet. After 100 cycles, the cycle capacity retention rate of the battery is only 90.36%. Compared with the Example 1, the initial specific discharge capacity of the Comparative Example 2 is lower, and the cycle capacity retention rate is also lower. In combination with the differences in the preparation process and the XPS test results, it can be known that the difference in the results is mainly due to the fact that the carbon element in the carbon coating layer in the Comparative Example 2 is mainly sp2 hybridization. This indicates that the ion conductivity and structural stability of the carbon coating layer formed by the carbon atoms bonded in the sp2 hybridization manner are not as good as those of the carbon coating layer formed by the carbon atoms bonded in the sp3 hybridization manner.

[0124] The Examples 2 and 3 respectively adopt the photochemical deposition and the plasma enhanced chemical vapor deposition to prepare the carbon coating layer, and the XPS test results of the products prepared are similar to those of the Example 1, and the carbon coating layers prepared both contain more carbon elements bonded in the sp3 hybridization manner. Therefore, the Examples 2 and 3 can achieve similar initial specific discharge capacity and cycle capacity retention rate to those of the Example 1.

[0125] The Example 4 adopts lithium indium chloride as the solid electrolyte, and also can achieve similar initial specific discharge capacity and cycle capacity retention rate to those of the Example 1, which indicates that the carbon coating layer of the present application can be suitable for a plurality of different solid electrolytes.

[0126] The Example 5 coats the carbon-coated solid electrolyte on the surface of the positive electrode active layer, and also can achieve similar initial specific discharge capacity and cycle capacity retention rate to those of the Example 1, which indicates that coating the carbon-coated solid electrolyte on the surface of the positive electrode sheet can also play a good ion conductivity role.

[0127] The Example 6 coats the carbon-coated solid electrolyte on the surface of the separator close to the positive electrode, and can achieve better initial specific discharge capacity and cycle capacity retention rate than those of the Example 1, which indicates that coating the carbon-coated solid electrolyte on the separator can play a better ion conductivity role, and is less likely to have a negative impact on the positive electrode sheet.

[0128] It should be noted that the above examples are only for illustrative purposes and do not mean a limitation on the present text.

[0129] It should be understood that, unless explicitly stated otherwise herein, the execution of the steps is not strictly limited in sequence, and the steps can be executed in other sequences. Moreover, at least a part of the steps in the preparation process can include a plurality of sub-steps or stages, which are not necessarily executed at the same time, but can be executed at different times, and the execution sequence of the sub-steps or stages is not necessarily sequential, but can be executed in rotation or alternation with at least a part of other steps or sub-steps or stages of other steps.

[0130] The various embodiments described in this specification are intended to be exemplary only. The phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The various embodiments described in this specification can be combined in any way, provided that the combination is not clearly inconsistent. The various illustrative components, as well as other components described herein, can be implemented as discrete components or integrated in the functionality of one or more other components.

[0131] The technical features of the above embodiments can be combined in any manner, and for the sake of brevity, not all possible combinations are described. However, any combination of the technical features is considered to be within the scope of the specification.

Claims

1. A carbon-coated solid electrolyte, comprising an electrolyte core and a carbon coating layer coated on a surface of the electrolyte core, wherein an X-ray photoelectron spectroscopy test result of the carbon coating layer has the following characteristics: carbon element has a first peak position corresponding to sp3 hybridization and a second peak position corresponding to sp2 hybridization, and a ratio of intensity of the first peak position to intensity of the second peak position is greater than or equal to 0.

1.

2. The carbon-coated solid-state electrolyte of claim 1, wherein, In the X-ray photoelectron spectroscopy test result of the carbon coating layer, carbon element has a composite peak between 284 eV and 287 eV formed by superposition of the first peak position and the second peak position, and after peak separation processing, the composite peak forms a first peak position between 284 eV and 285 eV and a second peak position between 285 eV and 286 eV, respectively.

3. The carbon-coated solid-state electrolyte according to any one of claims 1 to 2, wherein The carbon coating layer further comprises oxygen element, and the X-ray photoelectron spectroscopy test result of the carbon coating layer has the following characteristics: oxygen element has a peak position between 530 eV and 532 eV and a peak position between 528 eV and 530 eV.

4. The carbon-coated solid-state electrolyte according to any one of claims 1 to 3, wherein The thickness of the carbon coating layer is 1 nm to 100 nm.

5. The carbon-coated solid-state electrolyte according to any one of claims 1 to 4, wherein The material of the electrolyte core comprises one or more of an oxide solid electrolyte, a halide solid electrolyte and a polymer solid electrolyte. The oxide solid electrolyte is selected from one or more of lithium aluminum titanium phosphate, lithium aluminum germanium phosphate, lithium lanthanum zirconium oxide and lithium phosphorus oxynitride. The halide solid electrolyte is selected from one or more of lithium indium chloride, lithium yttrium chloride and lithium zirconium chloride.

6. The carbon-coated solid-state electrolyte according to any one of claims 1 to 5, wherein The particle size of the electrolyte core is 100 nm to 100 μm. 7.A battery comprising the carbon-coated solid electrolyte according to any one of claims 1 to 6.

8. The battery of claim 7, wherein, The positive electrode of the battery comprises a positive active layer, and the carbon-coated solid electrolyte is arranged in the positive active layer; or The positive electrode of the battery comprises a positive active layer and an ion-conducting layer arranged in a stack, and the carbon-coated solid electrolyte is arranged in the ion-conducting layer; or The battery comprises a positive electrode, a negative electrode and a separator arranged between the positive electrode and the negative electrode, and the carbon-coated solid electrolyte is arranged on a side of the separator close to the positive electrode.

9. The battery according to any one of claims 7 to 8, wherein The battery is a lithium ion battery, a solid-state battery or a semi-solid-state battery. 10.A power-consuming device, comprising a functional body and the battery according to any one of claims 7 to 9, wherein the battery is used to supply power to the functional body.

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