Composite electrode tab, method of manufacturing the same, and solid-state battery

Abstract

The application provides a composite pole piece and a preparation method thereof and a solid-state battery, and relates to the technical field of energy storage. The composite pole piece comprises a current collector layer and an active layer formed on the current collector layer. The active layer comprises an active material and a halide solid-state electrolyte. The halide solid-state electrolyte comprises Li3MCl 6‑x Br x， In the composite pole piece, the second halide solid-state electrolyte is transformed from a solid state into a liquid state and then from the liquid state into a solid state again. The surface roughness of the composite pole piece is 1.5 microns to 30 microns. On the one hand, the continuous conduction channel of lithium ions is formed, the transmission capacity of lithium ions is improved, the electrochemical performance of the solid-state battery is improved, and on the other hand, the interface contact between the composite pole piece and the solid-state electrolyte layer is effectively improved, and the internal resistance of the battery is effectively reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of energy storage, in particular to a composite electrode tab, a preparation method thereof and a solid-state battery. BACKGROUND

[0002] A solid-state battery is a kind of energy storage element, which can store and release electrical energy when needed. Compared with traditional liquid batteries, solid-state batteries use solid electrolytes instead of liquid or gel electrolytes for ion transport, which has higher safety, higher energy density, faster charging speed and longer cycle life.

[0003] In a solid-state battery, a solid-state electrolyte is located between a positive electrode and a negative electrode. Lithium ions are deintercalated from the positive electrode, transported through the electrolyte and intercalated into the negative electrode.

[0004] However, there are still some difficulties in the full commercialization of solid-state batteries. On the one hand, the solid-state electrolyte replaces the electrolyte as the transmission medium of lithium ions in the battery. Compared with the liquid-solid contact between the electrolyte and the electrode, the solid-solid contact between the solid-state electrolyte and the electrode forms a good interface contact, which leads to an increase in the internal resistance of the battery and is not conducive to the capacity of the battery. On the other hand, the traditional positive electrode tab and negative electrode tab are usually porous electrodes, and the electrolyte has fluidity. The electrolyte establishes the internal lithium ion transmission path of the positive electrode tab and / or the negative electrode tab by infiltrating the electrode. However, the solid-state electrolyte is in a solid state and cannot infiltrate the electrode. Even if the existing technology incorporates solid-state electrolyte particles into the electrode, the ion conductivity of the solid-state electrolyte and the solid-solid contact between the active material particles and the solid-state electrolyte particles affect the performance of the battery. SUMMARY

[0005] Therefore, it is necessary to provide a composite electrode tab, a preparation method thereof and a solid-state battery, which can effectively improve the interface contact performance between the electrode and the solid-state electrolyte layer, reduce the internal resistance of the battery, improve the lithium ion transmission capacity inside the electrode tab and inside the battery, and thus improve the rate performance and cycle performance of the battery.

[0006] In a first aspect, the present application provides a composite electrode tab, which comprises a current collector layer and an active layer formed on the current collector layer, and the active layer comprises an active material and a halide solid-state electrolyte, wherein the second halide solid-state electrolyte is converted from a solid state to a liquid state, and then converted from a liquid state to a solid state.

[0007] The surface roughness of the composite electrode tab is 1.5 μm to 30 μm.

[0008] In some embodiments, the halide solid-state electrolyte comprises Li3MCl 6-x Br xat least part of Li3MCl 6-x Br x forming a continuous structure in the active layer, wherein M is a trivalent metal element, and x satisfies 0 < x < 6.

[0009] In some embodiments, the halide solid-state electrolyte has a melting point of 80-200 ℃.

[0010] In some embodiments, M is selected from one or more of Ga 3+ , In 3+ , Al 3+ , Fe 3+ , Y 3+ , Sc 3+ , Bi 3+ , and trivalent lanthanide metals, and x satisfies 2 ≤ x ≤ 5.

[0011] In some embodiments, the composite electrode sheet has a porosity of 0.1%-10%.

[0012] In some embodiments, the halide solid-state electrolyte has an ionic conductivity λ satisfying λ ≥ 1 mS / cm. 6-x Br x

[0013] In some embodiments, the content of the halide solid-state electrolyte in the active layer increases in sequence in a direction away from the current collector layer.

[0014] In some embodiments, the composite electrode sheet comprises a first electrode layer and a plurality of second electrode layers, the first electrode layer comprises an active material, and the second electrode layers comprise an active material and the halide solid-state electrolyte; wherein the first electrode layer is formed on the composite electrode sheet, and the second electrode layers are formed on the first electrode layer.

[0015] In some embodiments, the composite electrode sheet is a composite positive electrode, and the mass fraction of the halide solid-state electrolyte in the active layer is 5%-40%; or,

[0016] the composite electrode sheet is a composite negative electrode, and the mass fraction of the halide solid-state electrolyte in the active layer is 8%-50%.

[0017] In a second aspect, the present application further provides a preparation method of a composite electrode sheet, the preparation method comprising:

[0018] preparing an electrode sheet precursor; the electrode sheet precursor comprises a current collector layer and an active layer, and the active layer comprises an active material and a halide solid-state electrolyte;

[0019] ​The pole piece precursor is subjected to hot-pressing treatment to obtain a composite pole piece; wherein the temperature of the hot-pressing treatment is greater than or equal to the melting point temperature of the halide solid-state electrolyte.

[0020] In some embodiments, the temperature of the hot-pressing treatment is 80-200℃; and / or, the time of the hot-pressing treatment is 0.5-30min; and / or, the pressure of the hot-pressing treatment is 10-500MPa.

[0021] In a third aspect, the present application also provides a solid-state battery comprising the composite pole piece.

[0022] Beneficial technical effects

[0023] The composite pole piece provided by the present application comprises an active electrode material and a halide solid-state electrolyte. On the one hand, the halide solid-state electrolyte changes from a liquid state to a solid state in the active layer, and the liquid halide solid-state electrolyte can penetrate everywhere in the active layer. Meanwhile, thanks to the high ionic conductivity of the halide solid-state electrolyte, a continuous and high-speed lithium ion transmission path can be formed inside the positive electrode or the negative electrode, thereby significantly improving the rate performance of the battery. On the other hand, the change of the halide solid-state electrolyte from a liquid state to a solid state can significantly improve the density of the halide solid-state electrolyte, thereby significantly improving the density and reducing the surface roughness of the composite pole piece when the halide solid-state electrolyte is combined with the positive electrode or the negative electrode active material to form the composite pole piece. This can effectively improve the interface contact between the composite pole piece and the solid-state electrolyte layer, and effectively reduce the internal resistance of the battery. When the composite pole piece is a composite negative electrode, the improvement of the surface roughness can help to reduce the uneven deposition of lithium ions on the negative electrode side, effectively prevent the generation and growth of lithium dendrites, and improve the safety performance of the battery.

[0024] By forming a mass fraction gradient of the halide solid-state electrolyte on the electrode side, the present application can fully utilize the density performance of the halide solid-state electrolyte to improve the interface performance of the composite pole piece and the solid-state electrolyte while maintaining the energy density of the battery. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 Schematic diagram of the preparation method of the composite pole piece of an embodiment. DETAILED DESCRIPTION

[0026] Reference will now be made in detail to the embodiments of the present application, one or more examples of which are described hereinbelow. Each example is provided as an explanation and not a limitation of the present application. Indeed, it will be apparent to one of ordinary skill in the art that numerous modifications and variations of the present application are possible in light of the above teachings. For example, features described or illustrated as part of one embodiment can be used with another embodiment to yield a still further embodiment.

[0027] Accordingly, it is intended to cover all such modifications and variations of this application as come within the scope of the appended claims and their equivalents. Other objects, features and aspects of the present application are disclosed in or are obvious from the following detailed description of the application, which is to be evaluated together in connection with the drawings. Those skilled in the art will appreciate that the description herein is by way of example only and is not intended to limit the overall scope of the application.

[0028] In the present application, the technical features described in an open way include both the closed technical solution consisting of the listed features and the open technical solution containing the listed features.

[0029] In the present application, when referring to a numerical interval, unless otherwise specified, the numerical interval is considered to be continuous and includes the minimum and maximum values of the range and every value between the minimum and maximum values. Further, when the range refers to integers, every integer between the minimum and maximum values of the range is included. In addition, when multiple ranges are provided to describe a feature or a characteristic, the ranges can be combined. In other words, unless otherwise specified, all ranges disclosed herein are to be understood as including any and all sub-ranges subsumed therein.

[0030] If not specified, all embodiments and optional embodiments of the present application can be combined to form new technical solutions.

[0031] If not specified, all technical features and optional technical features of the present application can be combined to form new technical solutions.

[0032] If not specified, all steps of the present application can be performed in sequence or randomly, and preferably in sequence. For example, the method comprises steps S12 and S14, indicating that the method can comprise steps S12 and S14 in sequence, or steps S14 and S12 in sequence. For example, it is mentioned that the method can further comprise step S16, indicating that step S16 can be added to the method in any order, for example, the method can comprise steps S12, S14 and S16, or steps S12, S16 and S14, or steps S16, S12 and S14, etc.

[0033] If not specified, the "comprise" and "include" mentioned in the present application represent an open type, and can also be a closed type. For example, the "comprise" and "include" can mean that other components not listed can also be included or contained, or only the listed components can be included or contained.

[0034] If not specifically stated, the term "or" is inclusive in this application. For example, the phrase "A or B" means "A, B, or both A and B." More specifically, any of the following satisfy the condition "A or B": A is true (or present) and B is false (or not present); A is false (or not present) and B is true (or present); or both A and B are true (or present).

[0035] Compared with liquid batteries, all-solid-state batteries have higher safety and higher energy density. However, since the all-solid-state battery uses a film prepared from a solid-state electrolyte powder as a medium for lithium ion transmission, the solid-state characteristics affect the contact between the solid-state electrolyte and the electrode and the conduction of lithium ions, resulting in a higher internal resistance of the prepared battery and poor rate performance and cycle performance. Since the solid-state electrolyte powder in the all-solid-state battery has poor flowability and has intervals between the particles, the transmission path of lithium ions is discontinuous, which reduces the transmission efficiency of lithium ions, thereby causing the performance of the all-solid-state battery to decrease.

[0036] The application provides a composite electrode tab, which comprises a current collector layer and an active layer formed on the current collector layer, and the active layer comprises an active material and a halide solid-state electrolyte. The second halide solid-state electrolyte is converted from a solid state to a liquid state and then from a liquid state to a solid state.

[0037] In the application, the halide solid-state electrolyte is added to the active layer and is converted from a liquid state to a solid state in the active layer, which can effectively improve the surface roughness of the composite electrode tab, reduce the internal resistance of the battery, and significantly improve the rate performance of the battery.

[0038] One possible guess is that the existing electrodes and solid-state electrolyte layers usually exhibit point-to-point contact between particles and particles, while in the application, the halide solid-state electrolyte is converted from a liquid state to a solid state in the active layer. The liquid halide solid-state electrolyte can penetrate everywhere in the active layer, adhere to the surface of the active material particles, and / or fill the pores between the active material particles to form a continuous structure. At the same time, thanks to the high ionic conductivity of the halide solid-state electrolyte, a continuous and high-speed lithium ion transmission path can be formed inside the positive electrode or the negative electrode, thereby significantly improving the rate performance of the battery. On the other hand, the conversion of the halide solid-state electrolyte from a liquid state to a solid state can significantly improve the density of the halide solid-state electrolyte, thereby significantly improving the density of the surface of the composite electrode tab when the halide solid-state electrolyte is combined with the active material of the positive electrode or the negative electrode to form a composite electrode tab. After the surface roughness is improved, the surface of the composite electrode tab is smoother, and the contact points between the composite electrode tab and the solid-state electrolyte layer are more, which can effectively improve the interface contact between the composite electrode tab and the solid-state electrolyte layer and effectively reduce the internal resistance of the battery. The above is only a possible guess about the mechanism of the technical solution of the application and does not constitute a limitation on the protection scope of the application.

[0039] The surface roughness of the composite tab can be, but is not limited to, 1.5 pm, 2 pm, 2.5 pm, 3 pm, 5 pm, 8 pm, 10 pm, 15 pm, 18 pm, 20 pm, 25 pm, or 30 pm. Within the above range, the composite tab can combine well with the solid-state electrolyte layer, optimizing the interface between the tab and the solid-state electrolyte layer. Further, the surface roughness of the composite tab can be 5 pm to 20 pm.

[0040] In some embodiments, the halide solid-state electrolyte comprises Li3MCl 6-x Br x , at least in part, Li3MCl 6-x Br x forms a continuous structure in the active layer, where M is a trivalent metal element, and x satisfies 0 < x < 6.

[0041] In some preferred embodiments, M is selected from one or more of Ga 3+ , In 3+ , Al 3+ , Fe 3+ , Y 3+ , Sc 3+ , Bi 3+ , and trivalent lanthanide metals, and x satisfies 2 < x < 5. Illustratively, Li3MCl 6-x Br x may be, but is not limited to, Li3Y 0.5 Dy 0.5 Cl3Br3, Li3In 0.5 Fe 0.5 Cl3Br3, Li3YCl3Br3.

[0042] In some embodiments, the halide solid-state electrolyte has a melting point of 80 °C to 200 °C.

[0043] In some embodiments, the composite tab has a porosity of 0.1% to 10%. The porosity of the composite tab can be, but is not limited to, 0.1%, 0.2%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5%, or 10%. The reason for the low porosity of the composite tab can be that at least part of the Li3MCl 6-x Br xThe continuous structure is formed in the active layer. The porosity of the composite electrode sheet is low, the ion transmission path is more, the diffusion of the ion is facilitated, and the overall volume energy density of the battery is improved. The lithium ion transmission path is established inside the electrode, Li3MCl 6-x Br x The ion conductivity is high, the effect similar to "electrolyte infiltration" is formed inside the composite electrode sheet, the internal resistance of the battery is reduced, and the rate performance and cycle performance of the battery are improved.

[0044] In some embodiments, the ion conductivity λ of Li3MCl 6-x Br x satisfies λ≥1 mS / cm; preferably, λ≥1.5 mS / cm, and more preferably, λ≥2 mS / cm.

[0045] In some of the embodiments, the content of the halide solid-state electrolyte in the active layer increases in turn in the direction away from the current collector layer. In this way, the content is high near the side of the solid-state electrolyte layer, which ensures the conduction of lithium ions, and the content is low away from the side of the solid-state electrolyte layer, which increases the proportion of the active material content and ensures the content of the active material, and is beneficial to improve the energy density of the battery prepared by the composite electrode sheet.

[0046] In some of the embodiments, the composite electrode sheet includes a first electrode layer and a plurality of second electrode layers, the first electrode layer includes an active material, and the second electrode layer includes an active material and a halide solid-state electrolyte; wherein the first electrode layer is formed on the composite electrode sheet, and the second electrode layer is formed on the first electrode layer.

[0047] In some embodiments, the second electrode layer is a plurality of second electrode layers, and the plurality of second electrode layers are located between the first electrode layer and the solid-state electrolyte layer; wherein the mass fraction of Li3MCl 6-x Br x increases in the direction close to the solid-state electrolyte layer.

[0048] In some of the embodiments, the composite electrode sheet is a composite positive electrode, and the mass fraction of the halide solid-state electrolyte in the active layer is 5% to 40%; or, the composite electrode sheet is a composite negative electrode, and the mass fraction of the halide solid-state electrolyte in the active layer is 8% to 50%. It can be understood that due to the different choices of the positive active material and the negative active material in the composite positive electrode and the composite negative electrode, the porosity of the initial positive electrode and the negative electrode is not the same. The density of the positive electrode material is larger than that of the negative electrode material, and the volume is smaller at the same mass ratio. Therefore, the volume of the halide electrolyte material used is smaller, and the mass fraction is smaller. Conversely, the mass fraction of the halide electrolyte material used in the negative electrode material is larger.

[0049] When the composite electrode sheet is a composite positive electrode, the mass ratio of the halide solid-state electrolyte in the composite positive electrode can be, but is not limited to, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, or 50%, etc. Within the above range, the proportion of the positive electrode active material is ensured, and the halide solid-state electrolyte can play a good lithium ion conduction role. Further, the mass ratio of the halide solid-state electrolyte in the composite positive electrode can be 15% to 35%.

[0050] When the composite electrode sheet is a composite negative electrode, the mass ratio of the halide solid-state electrolyte in the composite negative electrode can be, but is not limited to, 8%, 10%, 15%, 20%, 25%, 30%, 35%, or 40%, etc. Within the above range, the proportion of the negative electrode active material is ensured, and the halide solid-state electrolyte can play a good lithium ion conduction role. Further, the mass ratio of the halide solid-state electrolyte in the composite negative electrode can be 15% to 35%.

[0051] In some embodiments, the active material is a positive electrode active material, and the positive electrode active material includes, illustratively, a ternary positive electrode material, a lithium-rich manganese-based positive electrode material, lithium cobaltate, lithium nickel manganese oxide, lithium iron phosphate, and lithium manganese iron phosphate.

[0052] In some embodiments, the composite electrode sheet is a composite positive electrode, and the composite positive electrode further includes a positive electrode conductive agent and a positive electrode binder.

[0053] In some embodiments, the positive electrode conductive agent includes graphite, such as natural graphite or artificial graphite; carbon-based materials, such as carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, and thermal crack black; conductive fibers, such as carbon fibers and metal fibers; conductive tubes, such as carbon nanotubes; metal powders, such as fluorocarbon powders, aluminum powders, and nickel powders; conductive whiskers, such as zinc oxide and potassium titanate; conductive metal oxides, such as titanium oxides; and polyphenylene derivatives, and from the aspect of improving the conductivity, the positive electrode conductive agent can be preferably super conductive carbon black.

[0054] In some embodiments, the specific surface area of the conductive agent can be 80 m 2 / g to 200 m 2 / g, preferably 100 m 2 / g to 150 m 2 / g.

[0055] In some embodiments, the positive electrode binder includes at least one of polyvinylidene fluoride, polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, polyvinyl pyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene monomer, styrene-butadiene rubber, and fluoro rubber, preferably polytetrafluoroethylene. It should be noted that the selection of the positive electrode binder in the present application is related to the melting point of the halide solid electrolyte, and should satisfy: the melting point temperature of the positive electrode binder is greater than the melting point temperature of the halide solid electrolyte.

[0056] In a preferred embodiment, the binder includes a fiberized binder, which can be understood as a binder that can be transformed from a granular state to a fibrous state under the action of high shear force.

[0057] Illustratively, the fiberized binder includes one or more of polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP), polyethylene (PE), and polypropylene (PP).

[0058] In some embodiments, the thickness of the positive electrode active layer in the composite positive electrode can be 30 μm to 400 μm, for example, 30 μm, 40 μm, 50 μm, 80 μm, 110 μm, 200 μm, 300 μm, 400 μm, preferably 50 μm to 110 μm.

[0059] In some embodiments, the active material is a negative electrode active material, which is not particularly limited in the present application, and can be any material that can electrochemically occlude and release lithium ions, sodium ions, potassium ions, magnesium ions, or other s-block metal ions, such as carbonaceous materials, metal compound-based materials, or their oxides, carbides, nitrides, silicides, sulfides, phosphides, etc. These materials can be used alone or in any combination of two or more.

[0060] In some embodiments, a carbon material can be selected as the negative electrode active material, and one or more of the following can be selected: graphite, needle coke, amorphous carbon, carbon-containing mesophase, carbon fiber, and carbon material with low graphitization degree. The graphite can include natural graphite, artificial graphite, etc. In addition, materials obtained by coating carbon materials such as amorphous carbon and graphitized material can also be used. The amorphous carbon includes, but is not limited to, particles obtained by firing a bulk mesophase, and particles obtained by infusibilizing a carbon precursor and firing. As the carbonaceous material with low graphitization degree, particles obtained by firing an organic material at a temperature generally lower than 2500°C can be listed.

[0061] In some embodiments, the non-metallic material that can be used as the negative active material also includes silicon and its compounds, such as Si, SiOx (0≤x<2), and the like. Since the silicon-containing material is prone to swelling and easy to fall off from the negative current collector, and has poor electrical conductivity, it is often mixed with carbon materials, such as core-shell structures with a carbon coating layer, and the like.

[0062] In some embodiments, a metal compound can also be selected as the negative active material, such as a compound containing Li, Ag, Al, Bi, Cu, Ga, Ge, In, Ni, Pb, Sb, Si, Sn, Sr, Zn, and the like.

[0063] In an embodiment, when the negative active material is a non-metallic material such as carbon material, the negative binder can use a water-based binder, such as one or more of sodium hydroxymethyl cellulose, butyl rubber latex, polyacrylic acid, acrylic copolymer, cyclodextrin, and the like.

[0064] Referring to Figure 1 The application also provides a preparation method of the composite electrode sheet, which comprises the following steps:

[0065] S1, preparing an electrode sheet precursor; the electrode sheet precursor comprises a current collector layer and an active layer, and the active layer comprises an active material and a halide solid-state electrolyte, wherein M is a trivalent metal element, and x satisfies 0<x<6.

[0066] S2, heat-treating the electrode sheet precursor, and cooling to obtain a composite electrode sheet; wherein the heat-treating temperature is greater than or equal to the melting point temperature of the halide solid-state electrolyte.

[0067] The halide solid-state electrolyte has a certain flowability at a temperature higher than the melting point temperature. By increasing the halide solid-state electrolyte in the composite electrode sheet, the halide solid-state electrolyte is converted from a granular state to a flowable state during heat treatment, and flows in the pores between the active material particles. At least part of the halide solid-state electrolyte forms a continuous structure in the active layer, and can be partially filled in the gaps of the composite electrode sheet to reduce the gap between the active material and / or the halide solid-state electrolyte. The solid-state electrolyte conducts lithium ions by solid contact, and the lithium ion conduction efficiency of the granular solid-state electrolyte is limited. By continuously filling the halide solid-state electrolyte in the composite positive electrode, the lithium ion conduction channel is continuous, the conduction capacity of lithium ions is improved, and the electrochemical performance of the all-solid-state battery is improved.

[0068] In some embodiments, the melting point temperature of the halide solid-state electrolyte is 80℃~200℃.

[0069] In some embodiments, the temperature of the hot-pressing treatment is 80-200°C. The temperature of the hot-pressing treatment can be, but is not limited to, 80°C, 100°C, 120°C, 140°C, 150°C, 160°C, 180°C, 200°C, or 220°C, etc. In this way, the halide solid-state electrolyte can be ensured to have a certain flowability during the hot-pressing treatment, and the binder in the electrode tab will not be excessively melted. Further, the temperature of the hot-pressing treatment can be 80-200°C.

[0070] In some embodiments, the time of the hot-pressing treatment is 3-20 min, including but not limited to 3 min, 4 min, 5 min, 6 min, 8 min, 10 min, 12 min, 14 min, 15 min, 16 min, 18 min, or 20 min, etc. In this way, the halide solid-state electrolyte can flow within a certain time, has a suitable flow range, and in the case of flowing to the interface between the electrode tab and the solid-state electrolyte layer, it will not cause excessive loss of the solid-state electrolyte, and ensure the conduction ability of lithium ions. Further, the time of the hot-pressing treatment can be 5-15 min.

[0071] In some embodiments, the pressure of the hot-pressing treatment is 10-500 MPa, including but not limited to 10 MPa, 20 MPa, 50 MPa, 80 MPa, 100 MPa, 150 MPa, 200 MPa, 250 MPa, 300 MPa, 350 MPa, 400 MPa, 450 MPa, or 500 MPa, etc. In this way, the hot-pressing pressure can promote the flow of the halide solid-state electrolyte within a suitable range, and will not damage the structure of the electrode tab and the solid-state electrolyte layer. Further, the pressure of the hot-pressing treatment can be 50-250 MPa.

[0072] In some preferred embodiments, in step S1, a step S11 is further included: the active material is uniformly mixed with the conductive agent, the binder, and the halide solid-state electrolyte, and is placed in a high-shear device to perform a binder fiberization treatment to prepare an active layer; or the active material is uniformly mixed with the conductive agent and the halide solid-state electrolyte to form a mixture, the mixture is uniformly mixed with the binder, and is placed in a high-shear device to perform a binder fiberization treatment to prepare an active layer.

[0073] The application also provides a solid-state battery, which comprises the composite electrode tab described above. The solid-state battery can be a full solid-state battery.

[0074] In some embodiments, the solid-state battery comprises a solid-state electrolyte layer, which is arranged between the positive electrode or the composite positive electrode and the composite negative electrode or the negative electrode.

[0075] In some embodiments, at least one of the positive electrode and the negative electrode of the solid-state battery is the composite electrode tab described above, preferably the positive electrode is a composite positive electrode and the negative electrode is a composite negative electrode.

[0076] In some embodiments, the solid-state electrolyte layer comprises a solid-state electrolyte, which is not limited in the present application, and can be any conventional solid-state electrolyte material. The solid-state electrolyte material includes but is not limited to one or more of oxide solid-state electrolyte, sulfide solid-state electrolyte, halide solid-state electrolyte, hydride solid-state electrolyte, boride solid-state electrolyte, and nitride solid-state electrolyte.

[0077] In some embodiments, the oxide solid-state electrolyte can be selected from a crystalline oxide solid-state electrolyte or a glassy oxide solid-state electrolyte. The crystalline oxide solid-state electrolyte includes but is not limited to perovskite-type oxide solid-state electrolyte, NASICON-type oxide solid-state electrolyte, LISICON-type oxide solid-state electrolyte, and Garnet-type oxide solid-state electrolyte, etc. The glassy oxide solid-state electrolyte includes but is not limited to LiPON-type oxide solid-state electrolyte, etc.

[0078] In some embodiments, the perovskite-type oxide solid-state electrolyte includes but is not limited to one or more of Li 3.3 La 0.53 TiO3, LiSr1 .65 Zr 1.3 Ta 1.7 O9, Li 2x-y Sr 1-x Ta y Zr 1-y O3 (wherein x = 0.75y and 0.60 < y < 0.75), Li 3 / 8 Sr 7 / 16 Nb 3 / 4Zr 1 / 4 O3, Li 3x La (2 / 3-x) TiO3 (wherein 0 < x < 0.25).

[0079] In some embodiments, the NASICON-type oxide solid-state electrolyte can be defined by LiMM'(PO4)3, wherein M and M' are independently selected from Al, Ge, Ti, Sn, Hf, Zr, and La. For example, in certain variations, the NASICON-type oxide solid-state electrolyte includes but is not limited to Li 1+x Al x Ge 2-x (PO4)3 (LAGP) (wherein 0 ≤ x ≤ 2), Li 1+x Al x Ti 2-x(PO4)3(LATP) (wherein 0 < x < 2), Li 1+x Y x Zr 2-x (PO4)3(LYZP) (wherein 0 < x < 2), Li 1.3 Al 0.3 Ti 1.7 one or more of LiTi2(PO4)3, LiGeTi(PO4)3, LiGe2(PO4)3, LiHf2(PO4)3.

[0080] In some embodiments, LISICON-type oxide solid state electrolytes include, but are not limited to, Li 14 Zn(GeO4)4, Li 3+x (P 1-x Si x )O4 (wherein 0 < x < 1), Li 3+x Ge x V 1-x O4 (wherein 0 < x < 1).

[0081] In some embodiments, Garnet-type oxide solid state electrolytes include, but are not limited to, Li 6.5 La3Zr 1.75 Te 0.25 O 12 , Li7La3Zr2O 12 , Li 6.2 Ga 0.3 La 2.95 Rb 0.05 Zr2O 12 , Li 6.85 La 2.9 Ca 0.1 Zr 1.75 Nb 0.25 O 12 , Li 6.25 Al 0.25 La3Zr2O 12 , Li 6.75 La3Zr 1.75 Nb 0.25 O 12

[0082] In some embodiments, sulfide solid state electrolytes include, but are not limited to, Li2S-P2S5, Li2S-P2S5-MS x (wherein M is Si, Ge, and Sn and 0 < x < 2), Li 3.4 Si 0.4 P 0.6 S4, Li 10 ​GeP2S 11.7 O 0.3 , Li 9.6 P3S 12 , Li7P3S 11 , Li9P3S9O3, Li 10.35 Si 1.35 P 1.65 S 12 , Li 9.81 Sn 0.81 P 2.19 S 12 , Li 10 (Si 0.5 Ge 0.5 )P2S 12 , Li(Ge 0.5 Sn 0.5 )P2S 12 , Li(Si 0.5 Sn 0.5 )PsS 12 , Li 10 GeP2S 12 (LGPS), Li6PS5X (where X is CI, Br, or I), Li7P2S8I, Li 10.35 Ge 1.35 P 1.65 S 12 , Li 3.25 Ge 0.25 P 0.75 S4, Li 10 SnP2S 12 , Li 10 SiP2S 12 , Li 9.54 Si 1.74 P 1.44 S 11.7 CI 0.3 , xLi2S-(1-x)P2S5 (where 0.5 < x < 0.7).

[0083] In some embodiments, the halide solid state electrolyte includes one or more halide-based materials including, but not limited to, Li2CdCl4, Li2MgCl4, Li2CdI4, Li2ZnI4, Li3OCl, Li2ZrCl6, Li2HfCl6, Li3InCl6, Li3InCl6, Li3YCl6, L3ScCl6, Li5ZnI4, Li3OCl 1-x Br x (where 0 < x < 1).

[0084] In some embodiments, the hydride solid-state electrolyte includes, but is not limited to, one or more hydride-based materials such as Li3AlH6, LiBH4, LiBH4-LiX (where X is one of Cl, Br, and I), LiNH2, Li2NH, LiBH4-LiNH2.

[0085] In some embodiments, the borate solid-state electrolyte includes, but is not limited to, one or more borate-based materials such as Li2B4O7, Li2O-(B2O3)-(P2O5).

[0086] In some embodiments, the nitride solid-state electrolyte includes, but is not limited to, one or more nitride-based materials such as Li3N, Li7PN4, LiSi2N3, LiPON.

[0087] It can be understood that the above-mentioned oxide solid-state electrolyte, sulfide solid-state electrolyte, halide solid-state electrolyte, hydride solid-state electrolyte, borate solid-state electrolyte, nitride solid-state electrolyte, and the like are all known in the art, and the above-mentioned materials are only illustrative examples and are not a limitation on the scope of protection. Any known solid-state electrolyte material can be used in the present application without deviating from the inventive concept of the present application.

[0088] In some preferred embodiments, the solid-state electrolyte layer includes a halide solid-state electrolyte.

[0089] The following are specific examples.

[0090] Example 1

[0091] The present example provides a composite positive electrode, the composite positive electrode includes a current collector aluminum foil and an active layer formed on the surface of the aluminum foil, the active layer includes an active material NCM811 and Li3YCl3Br3, the surface roughness of the composite positive electrode is 12 μm. The porosity of the composite positive electrode is 5.2%. The ionic conductivity of Li3YCl3Br3 is 2.34 mS / cm. The melting point of Li3YCl3Br3 is 115 ℃.

[0092] A composite negative electrode, the composite positive electrode includes a current collector copper foil and a negative active layer formed on the surface of the copper foil, the negative active layer includes an active material graphite and Li3YCl3Br3, the surface roughness of the composite negative electrode is 14 μm. The porosity of the composite negative electrode is 8.5%. The ionic conductivity of Li3YCl3Br3 is 2.34 mS / cm.

[0093] The present example provides a method for preparing a composite positive electrode, including the following steps:

[0094] A composite positive electrode is prepared. NCM811, PTFE, super-P, and Li3YCl3Br3 are uniformly mixed in a mass ratio of 80:3:2:15, placed in a high-shear equipment mixer, and subjected to fiberization treatment to form a first mixture. The first mixture is subjected to rolling to form a first positive electrode layer. The rolling temperature is 60°C, and the rolling time is 5 min.

[0095] The positive electrode current collector and the first positive electrode layer are stacked and subjected to hot-pressing treatment to form a composite positive electrode after cooling. The hot-pressing temperature is 150°C, the hot-pressing time is 10 min, and the hot-pressing pressure is 120 MPa.

[0096] The present embodiment provides a method for preparing a composite negative electrode, comprising the following steps:

[0097] A first negative electrode layer is prepared. A negative electrode active material graphite, (CMC+SBR), super-P, and Li3YCl3Br3 are uniformly mixed in a mass ratio of 69:4:2:25, placed in a high-shear equipment mixer, and subjected to fiberization treatment to form a second mixture. The second mixture is subjected to rolling to form a first negative electrode layer. The rolling temperature is 60°C, and the rolling time is 5 min.

[0098] The negative electrode current collector and the first negative electrode layer are stacked and subjected to hot-pressing treatment to form a composite negative electrode after cooling. The hot-pressing temperature is 120°C, the hot-pressing time is 12 min, and the hot-pressing pressure is 200 MPa.

[0099] The present embodiment also provides a solid-state battery comprising the composite positive electrode and the composite negative electrode and a solid-state electrolyte layer. The solid-state electrolyte layer comprises a halide solid-state electrolyte Li2ZrCl6 and a binder PTFE, and the mass ratio of the two is 97:3.

[0100] Example 2

[0101] Example 2 differs from Example 1 in that the mass ratio of Li3YCl3Br3 in the composite positive electrode is 40%, and the surface roughness of the composite positive electrode is 1.5 μm. The ionic conductivity of Li3YCl3Br3 is 2.34 mS / cm. The melting point of Li3YCl3Br3 is 115°C.

[0102] In the composite negative electrode, the mass ratio of Li3YCl3Br3 is 50%, and the surface roughness of the composite negative electrode is 1.5 μm. The ionic conductivity of Li3YCl3Br3 is 2.34 mS / cm. The melting point of Li3YCl3Br3 is 115°C.

[0103] Example 3

[0104] Example 3 differs from Example 1 in that in the composite positive electrode, the mass ratio of Li3YCl3Br3 is 5%, and the surface roughness of the composite positive electrode is 30 pm. The ionic conductivity of Li3YCl3Br3 is 2.34 mS / cm. The melting point of Li3YCl3Br3 is 115 °C.

[0105] In the composite negative electrode, the mass ratio of Li3YCl3Br3 is 8%, and the surface roughness of the composite negative electrode is 30 pm. The ionic conductivity of Li3YCl3Br3 is 2.34 mS / cm. The melting point of Li3YCl3Br3 is 115 °C.

[0106] Example 4

[0107] Example 4 differs from Example 1 in that in the composite positive electrode, the active layer comprises the active material NCM811 and Li3Y 0.5 Dy 0.5 Cl3Br3, and the mass ratio of Li3Y 0.5 Dy 0.5 Cl3Br3 is 15%, and the surface roughness of the composite positive electrode is 15 pm. The ionic conductivity of Li3Y 0.5 Dy 0.5 Cl3Br3 is 2.72 mS / cm. The melting point of Li3Y 0.5 Dy 0.5 Cl3Br3 is 120 °C.

[0108] In the composite negative electrode, the active layer comprises the negative active material graphite and Li3Y 0.5 Dy 0.5 Cl3Br3, and the mass ratio of Li3Y 0.5 Dy 0.5 Cl3Br3 is 25%, and the surface roughness of the composite negative electrode is 17 pm. The ionic conductivity of Li3Y 0.5 Dy 0.5 Cl3Br3 is 2.72 mS / cm. The melting point of Li3Y 0.5 Dy 0.5 Cl3Br3 is 120 °C.

[0109] Example 5

[0110] Example 5 differs from Example 1 in that in the composite positive electrode, the active layer comprises the active material NCM811 and Li3In 0.5 Fe 0.5 Cl3Br3, and the mass ratio of Li3In 0.5 Fe 0.5 Cl3Br3 is 15%, and the surface roughness of the composite positive electrode is 17 pm. The ionic conductivity of Li3In 0.5 Fe 0.5The ion conductivity of Cl3Br3 is 2.48 mS / cm. 0.5 Fe 0.5 The melting point of Cl3Br3 is 125℃.

[0111] In the composite negative electrode, the active layer comprises the negative active material graphite and Li3In 0.5 Fe 0.5 Cl3Br3, Li3Y 0.5 Dy 0.5 The mass ratio of Cl3Br3 is 25%, and the surface roughness of the composite negative electrode is 19 μm. Li3In 0.5 Fe 0.5 The ion conductivity of Cl3Br3 is 2.48 mS / cm. Li3In 0.5 Fe 0.5 The melting point of Cl3Br3 is 125℃.

[0112] Example 6

[0113] The present embodiment provides a composite positive electrode, the composite positive electrode comprises a current collector aluminum foil and an active layer formed on the surface of the aluminum foil, the active layer comprises an active material NCM811 and Li3YCl3Br3, and the surface roughness of the composite positive electrode is 18 μm. The porosity of the composite positive electrode is 7.2%. The ion conductivity of Li3YCl3Br3 is 2.34 mS / cm. The melting point of Li3YCl3Br3 is 115℃.

[0114] A composite negative electrode, the composite positive electrode comprises a current collector copper foil and a negative active layer formed on the surface of the copper foil, the negative active layer comprises an active material graphite and Li3YCl3Br3, and the surface roughness of the composite negative electrode is 23 μm. The porosity of the composite negative electrode is 11%. The ion conductivity of Li3YCl3Br3 is 2.34 mS / cm.

[0115] The present embodiment provides a preparation method of a composite positive electrode, comprising the following steps:

[0116] A first positive electrode layer is prepared, NCM811, Li3YCl3Br3, PTFE and super-P are uniformly mixed in a mass ratio of 90:5:3:2, and are placed in a high shear equipment mixer for fiberization treatment to form a first mixture. The first mixture is rolled to form a first positive electrode layer. The rolling temperature is 60℃, and the rolling time is 5 min.

[0117] A second positive electrode layer is prepared by uniformly mixing NCM811, Li3YCl3Br3, PTFE and super-P according to a mass ratio of 75:20:3:2, placing the mixture into a high-shear equipment mixer, performing fiberization treatment to form a second mixture, and rolling the second mixture to form the second positive electrode layer; the rolling temperature is 60°C and the rolling time is 5 min.

[0118] A third mixture is prepared by uniformly mixing NCM811, Li3YCl3Br3, PVDF and super-P according to a mass ratio of 55:40:3:2, placing the mixture into a high-shear equipment mixer, performing fiberization treatment to form a third mixture, and rolling the third mixture to form the second positive electrode layer; the rolling temperature is 60°C and the rolling time is 5 min.

[0119] The positive electrode current collector, the first positive electrode layer, the second positive electrode layer and the third positive electrode layer are sequentially stacked and hot-pressed to form a composite positive electrode after cooling; the hot-pressing temperature is 150°C, the hot-pressing time is 10 min and the hot-pressing pressure is 120 MPa.

[0120] The embodiment provides a preparation method of a composite negative electrode, including the following steps:

[0121] A first negative electrode layer is prepared by mixing a negative electrode active material graphite, Li3YCl3Br3, (CMC+SBR) and super-P in deionized water according to a mass ratio of 86:8:4:2, uniformly stirring the mixture to obtain a first negative electrode layer slurry, coating the first negative electrode layer slurry on a copper foil surface and performing drying treatment to obtain the first negative electrode layer on the copper foil surface; the drying temperature is 70°C.

[0122] A second negative electrode layer is prepared by mixing a negative electrode active material graphite, Li3YCl3Br3, (CMC+SBR) and super-P in deionized water according to a mass ratio of 74:20:4:2, uniformly stirring the mixture to obtain a second negative electrode layer slurry, coating the second negative electrode layer slurry on the first negative electrode layer surface and performing drying treatment to obtain the second negative electrode layer.

[0123] A second negative electrode layer is prepared by mixing a negative electrode active material graphite, Li3YCl3Br3, (CMC+SBR) and super-P in deionized water according to a mass ratio of 74:20:4:2, uniformly stirring the mixture to obtain a second negative electrode layer slurry, coating the second negative electrode layer slurry on the first negative electrode layer surface and performing drying treatment to obtain the second negative electrode layer.

[0124] The second negative electrode layer is prepared by mixing a negative electrode active material graphite, Li3YCl3Br3, (CMC+SBR) and super-P in deionized water according to a mass ratio of 74:20:4:2, uniformly stirring the mixture to obtain a second negative electrode layer slurry, coating the second negative electrode layer slurry on the first negative electrode layer surface and performing drying treatment to obtain the second negative electrode layer.

[0125] The embodiment also provides a solid-state battery, which comprises the composite positive electrode and the composite negative electrode and a solid-state electrolyte layer. The solid-state electrolyte layer comprises a first halide solid-state electrolyte Li2ZrCl6 and a binder PTFE, and the mass ratio of the two is 97:3.

[0126] Comparative Example 1

[0127] The difference between Comparative Example 1 and Example 1 is that:

[0128] The mass ratio of Li3YCl3Br3, NCM811, PTFE and super-P in the composite positive electrode is 95:3:2;

[0129] The mass ratio of Li3YCl3Br3, graphite, (CMC+SBR) and super-P in the composite negative electrode is 94:4:2.

[0130] Comparative Example 2

[0131] The difference between Comparative Example 2 and Example 1 is that:

[0132] Li3YCl3Br3 in the composite positive electrode and the composite negative electrode is replaced by Li2ZrCl6.

[0133] Comparative Example 3

[0134] The difference between Comparative Example 3 and Example 1 is that:

[0135] Li3YCl3Br3 in the composite positive electrode and the composite negative electrode is replaced by LLZO.

[0136] Comparative Example 4

[0137] The preparation method of Comparative Example 4 is basically the same as that of Example 1, and the difference is that:

[0138] No hot-pressing process.

[0139] The raw materials A, B, C and D in the preparation methods of Examples 1-6 and Comparative Examples 1-4 are as follows: drying, calcination (by way of example only), etc. The process parameters are as shown in Table 1 below:

[0140] Table 1

[0141]

[0142] The composite positive electrode and the composite negative electrode prepared in Examples 1-6 and Comparative Examples 1-3 and the further prepared solid-state battery are subjected to performance tests, and the test results are shown in Table 1 and Table 2.

[0143] Among them, the test conditions or test standards of each performance test item are as follows:

[0144] (1) Melting point test

[0145] The melting point of the solid electrolyte material is measured by differential scanning calorimetry, in which the solid electrolyte material is placed in a crucible and heated from 30°C to 1000°C at a rate of 10°C / min under a nitrogen atmosphere.

[0146] (2) Porosity test

[0147] True density test: The true density of the composite cathode is obtained by a true density instrument. The test procedure is as follows: after turning on the power, preheat according to the requirements of the instrument manual to ensure that the instrument reaches a stable working state. Place the sample to be tested in the sample cell, and press the measurement button. The instrument will automatically measure the density. After the measurement is completed, the instrument will automatically record the data and calculate the true density value p 真 .

[0148] Compacted density test: 100 mg of powder is added to a φ10 mm mold, a pressure of 375 MPa is applied and held for 3 min, and then the compacted sheet is obtained by demolding. The thickness is measured, and the compacted density p 压实 .

[0149] Porosity: The porosity is (p 真 -p 压实 ) / p 真

[0150] (3) Surface roughness test

[0151] Place the electrolyte sheet under a high-precision optical microscope for observation. In the 3D imaging mode, the surface height distribution information of the electrolyte sheet within 200*300 μm 2 can be obtained. The surface roughness can be obtained by counting the maximum surface height difference of the electrolyte sheet.

[0152] (4) Battery performance test

[0153] The battery performance is tested using a LAND CT2001A battery test system. The composite cathode and composite anode of Examples 1-6 and Comparative Examples 1-4 are prepared into button cells, which are subjected to charge-discharge test, rate test and cycle test in the voltage range of 2.45-4.2V. The battery performance test is completed in a 25°C constant temperature box.

[0154] Table 2

[0155]

[0156] As can be seen from Table 2 above, the continuous halide solid electrolyte is provided in the composite electrode sheet, and the battery rate performance is significantly improved. The surface roughness of the composite electrode sheet is low, which can effectively improve the interface contact between the composite electrode sheet and the solid electrolyte layer, and effectively reduce the internal resistance of the battery.

[0157] By hot pressing, the porosity of the pole piece is within a suitable range, a continuous conduction channel for forming lithium ions is formed, the transmission capacity of lithium ions is improved, and the electrochemical performance of the all-solid-state battery is improved.

[0158] The technical features of the above-mentioned embodiments can be combined arbitrarily, and in order to make the description simple, all possible combinations of each technical feature in the above-mentioned embodiments are not described, however, as long as the combination of the technical features does not exist contradictory, it should be considered as the scope of the description.

[0159] The above-mentioned embodiments only express several implementation manners of the present application, the description is more specific and detailed, but it should not be understood as a limitation to the patent application scope. It should be pointed out that for ordinary skilled in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which all belong to the protection scope of the present application. Therefore, the patent protection scope of the present application should be subject to the appended claims.

Claims

1. A composite electrode, characterized in that, The composite electrode includes a current collector layer and an active layer formed on the surface of the current collector layer. The active layer includes an active material and a halide solid electrolyte, wherein the halide solid electrolyte is transformed from a solid state to a liquid state and then from a liquid state to a solid state. The surface roughness of the composite electrode is 1.5 μm to 30 μm. The halide solid electrolyte includes Li3MCl 6-x Br x And at least part of Li3MCl 6-x Br x A continuous structure is formed in the active layer, wherein M is a trivalent metal element and x satisfies 0 < x < 6; The melting point of the halide solid electrolyte is 80℃~200℃; The Li3MCl 6-x Br x The ionic conductivity λ satisfies λ≥1 mS / cm; The Li3MCl 6-x Br x Including Li3YCl3Br3, Li3Y 0.5 Dy 0.5 Cl3Br3, Li3In 0.5 Fe 0.5 One of Cl3Br3.

2. The composite electrode according to claim 1, characterized in that, The porosity of the composite electrode is 0.1% to 10%.

3. The composite electrode according to claim 1, characterized in that, Along the direction away from the current collector layer, the mass percentage of the halide solid electrolyte in the active layer gradually increases.

4. The composite electrode according to claim 3, characterized in that, The composite electrode includes a first electrode layer and a plurality of second electrode layers. The first electrode layer includes an active material, and the second electrode layers include an active material and the halide solid electrolyte. The first electrode layer is formed on the composite electrode, and the second electrode layers are formed on the first electrode layer.

5. The composite electrode according to claim 1, characterized in that, The composite electrode is a composite positive electrode, in which the mass percentage of halide solid electrolyte in the active layer is 5% to 40%; or, the composite electrode is a composite negative electrode, in which the mass percentage of halide solid electrolyte in the active layer is 8% to 50%.

6. A method for preparing a composite electrode as described in any one of claims 1 to 5, characterized in that, Includes the following steps: Prepare an electrode precursor; the electrode precursor includes a current collector layer and an active layer, the active layer including an active material and a halide solid electrolyte; The electrode precursor is hot-pressed to obtain a composite electrode; wherein the hot-pressing temperature is greater than or equal to the melting point temperature of the halide solid electrolyte.

7. The preparation method according to claim 6, characterized in that, The hot pressing temperature is 80℃~200℃; and / or, The hot pressing time is 0.5 min to 30 min; and / or, The pressure for hot pressing is 10MPa~500MPa.

8. A solid-state battery, characterized in that, The solid-state battery includes the composite electrode as described in any one of claims 1 to 5.

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