Phosphorus-based negative electrode material and preparation method and application thereof

Abstract

The invention relates to the technical field of solid-state batteries, in particular to a phosphorus-based negative electrode material and a preparation method and application thereof. The invention provides application of a phosphorus-based negative electrode material in an all-solid-state lithium battery. The phosphorus-based negative electrode material comprises modified phosphorus and / or a composite material containing modified phosphorus. The application advantage that the modified phosphorus and / or the composite material containing the modified phosphorus are / is adopted as the negative electrode of the all-solid-state lithium battery is remarkable, phosphorus has high theoretical specific capacity and moderate lithiation potential, the high energy density of the all-solid-state battery can be achieved, growth of lithium dendrites can be effectively inhibited, and therefore the potential of rapid charging of the all-solid-state battery can be brought into full play; and moreover, the phosphorus resource is rich, the chemical and electrochemical properties are stable, and good sustainability is achieved. And the problems of dissolution attenuation, slow dynamics and the like of the liquid phosphorus negative electrode are solved.

Description

Technical Field

[0001] The present invention relates to the field of solid-state battery technology, and specifically, to phosphorus-based negative electrode materials, preparation methods and applications thereof; more specifically, to applications of phosphorus-based negative electrode materials in all-solid-state lithium batteries, phosphorus-based negative electrode materials for all-solid-state lithium batteries, preparation methods of phosphorus-based negative electrode materials for all-solid-state lithium batteries, phosphorus-based negative electrodes and all-solid-state lithium batteries. Background Art

[0002] All-solid-state lithium batteries (ASSLBs), a breakthrough in electrochemical energy storage, are poised to revolutionize industries ranging from consumer electronics to electric vehicles and renewable energy grids. Compared to traditional organic liquid electrolytes, the use of solid-state electrolytes enables battery systems to be non-flammable, leak-proof, and stable at high temperatures, as well as possessing a bipolar battery structure, significantly improving the efficiency of cell-to-pack integration. The resurgence of high-capacity, low-potential anode materials such as lithium metal and silicon has reignited the current research boom in all-solid-state batteries. Although academia and industry have invested significant effort in developing all-solid-state configurations for these two anodes, lithium dendrite growth and chemical-mechanical failure, particularly at high areal capacities, pose a serious threat to the safety and fast-charging advantages promised by all-solid-state lithium batteries.

[0003] In fact, the field has recognized that the lithium dendrite problem in solid electrolytes is much more challenging than in liquid electrolytes, mainly due to the non-uniform and obstructive solid-solid contact interface. To solve this problem, it is necessary to develop high-energy negative electrode materials that are essentially unaffected by lithium deposition reactions. + / Li 0 The equilibrium potential of the electrode is 1.55 V. From a thermodynamic point of view, this characteristic enables it to achieve an electrode reaction without lithium deposition under certain conditions. However, its high redox potential and low theoretical capacity (175 mAh g -1 ) limits its application in high-energy systems.

[0004] Phosphorus is abundant in the earth's crust (0.1 wt%) and has a high theoretical capacity (2596 mAh g -1 ) shows excellent negative electrode potential. More importantly, the relatively balanced redox potential of the phosphorus negative electrode (about 0.7V, relative to Li + / Li 0) can provide a large overpotential margin, thereby effectively avoiding the occurrence of lithium metal deposition reactions even under high current conditions, while maintaining a low potential to achieve a higher energy density. Although significant research progress has been made in the field of phosphorus anodes in liquid systems, they still face degradation problems such as dissolution of lithium polyphosphide and dynamic interfacial growth. In addition, due to the low intrinsic electronic / ionic conductivity and multiphase conversion reaction characteristics, phosphorus anodes usually exhibit poor rate performance in liquid systems.

[0005] Therefore, the development of solid phosphorus-based anodes will solve the problems of dissolution decay and slow kinetics faced by liquid phosphorus anodes, thereby building a new type of all-solid-state battery with high safety and high energy density.

[0006] In view of this, the present invention is proposed. Summary of the Invention

[0007] The first objective of the present invention is to provide the application of phosphorus-based negative electrode materials in all-solid-state lithium batteries. The use of modified phosphorus and / or composite materials containing modified phosphorus as negative electrodes for all-solid-state lithium batteries offers significant advantages. Phosphorus has a high theoretical specific capacity and a moderate lithiation potential, which not only contributes to the high energy density of all-solid-state batteries but also effectively inhibits the growth of lithium dendrites, thereby fully realizing their fast-charging potential. Furthermore, phosphorus is abundant in resources, has stable chemical and electrochemical properties, and possesses good sustainability. Finally, solid-state electrolytes address the problems of dissolution decay and slow kinetics faced by liquid phosphorus negative electrodes.

[0008] A second objective of the present invention is to provide a phosphorus-based anode material for all-solid-state lithium batteries. Phosphorus has a high theoretical specific capacity and a moderate lithiation potential, which not only contributes to the high energy density of all-solid-state batteries but also effectively inhibits the growth of lithium dendrites, thereby fully realizing their fast-charging potential. Furthermore, phosphorus is abundant in resources, has stable chemical and electrochemical properties, and possesses good sustainability.

[0009] The third purpose of the present invention is to provide a method for preparing phosphorus-based negative electrode materials for all-solid-state lithium batteries. This process significantly reduces the use of organic solvents and can improve the compatibility between phosphorus-based negative electrode materials and solid electrolytes. At the same time, the process is simple to operate, has a short process flow, and has low production costs, which helps to achieve uniform dispersion of the components.

[0010] The fourth object of the present invention is to provide a phosphorus-based negative electrode, whose relatively balanced redox potential can provide a larger overpotential margin, which can effectively avoid the occurrence of lithium metal deposition reaction even under higher current conditions, while maintaining a lower potential to achieve a higher energy density.

[0011] A fifth object of the present invention is to provide an all-solid-state lithium battery having high specific energy and long cycle stability.

[0012] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are adopted:

[0013] The present invention first provides an application of a phosphorus-based negative electrode material in an all-solid-state lithium battery. The phosphorus-based negative electrode material comprises modified phosphorus and / or a composite material containing the modified phosphorus.

[0014] Furthermore, the modified phosphorus is mainly prepared by ball milling red phosphorus.

[0015] Furthermore, the particle size distribution of the modified phosphorus is 1 to 10 μm.

[0016] Furthermore, the particle size distribution of the modified phosphorus is 2 to 5 μm.

[0017] Furthermore, in addition to the modified phosphorus, the composite material further comprises at least one of a carbon material and a functional additive.

[0018] Furthermore, the carbon material includes at least one of natural graphite, Super P, carbon nanotubes, Ketjen black and hard carbon.

[0019] Furthermore, the functional additive includes at least one of metal bismuth, metal antimony, metal germanium, metal indium, metal tin and metal gallium.

[0020] Furthermore, the mass fraction of the carbon material in the composite material is 3% to 50%.

[0021] Furthermore, the mass fraction of the functional additive in the composite material is 10% to 70%.

[0022] The present invention further provides a phosphorus-based negative electrode material for an all-solid-state lithium battery, wherein the phosphorus-based negative electrode material comprises modified phosphorus and / or a composite material containing the modified phosphorus; wherein the modified phosphorus is mainly prepared by ball milling red phosphorus.

[0023] Furthermore, in addition to the modified phosphorus, the composite material further comprises at least one of a carbon material and a functional additive.

[0024] Furthermore, the carbon material includes at least one of natural graphite, Super P, carbon nanotubes, Ketjen black and hard carbon.

[0025] Furthermore, the functional additive includes at least one of metal bismuth, metal antimony, metal germanium, metal indium, metal tin and metal gallium.

[0026] Furthermore, the mass fraction of the carbon material in the composite material is 3% to 50%.

[0027] Furthermore, the mass fraction of the functional additive in the composite material is 10% to 70%.

[0028] The present invention also provides a method for preparing a phosphorus-based negative electrode material for an all-solid-state lithium battery, comprising the following steps: subjecting red phosphorus to a first ball milling to obtain the modified phosphorus; optionally, mixing the modified phosphorus with a carbon material and subjecting the mixed material to a second ball milling to obtain a phosphorus / carbon composite material; or, subjecting the modified phosphorus to a heat treatment in a gaseous organic carbon source atmosphere to obtain a phosphorus / carbon composite material; optionally, mixing the modified phosphorus with a functional additive and subjecting the mixed material to grinding to obtain a phosphorus / additive composite material; or, mixing the phosphorus / carbon composite material with a functional additive and subjecting the mixed material to grinding to obtain a phosphorus / carbon / additive composite material.

[0029] Furthermore, the rotation speed of the first ball mill is 400-600 r / min, and the time of the first ball mill is 5-40 hours.

[0030] Furthermore, the rotation speed of the second ball mill is 250 to 550 r / min, and the time of the second ball mill is 5 to 30 hours.

[0031] Furthermore, the gaseous organic carbon source includes at least one of methane, ethylene and acetylene.

[0032] Furthermore, the heat treatment includes: heating the temperature to 400-550° C. at a heating rate of 5-10° C. / min and keeping the temperature for 2-10 hours.

[0033] Furthermore, the grinding time is 20 to 30 minutes.

[0034] The present invention further provides a phosphorus-based negative electrode, including a phosphorus-based negative electrode material for an all-solid-state lithium battery.

[0035] Furthermore, the mass fraction of the phosphorus-based negative electrode material in the phosphorus-based negative electrode is 35% to 80%.

[0036] Furthermore, the phosphorus-based negative electrode further includes at least one of a binder, a conductor and an electrolyte.

[0037] The present invention also provides an all-solid-state lithium battery, comprising a phosphorus-based negative electrode.

[0038] Compared with the prior art, the present invention has the following beneficial effects:

[0039] (1) The present invention has significant advantages in using modified phosphorus and / or composite materials containing modified phosphorus as negative electrodes for all-solid-state lithium batteries. Specifically, phosphorus has a high theoretical specific capacity and a moderate lithiation potential, which not only helps to achieve a high energy density for all-solid-state batteries, but also effectively inhibits the growth of lithium dendrites, thereby fully realizing its potential for fast charging. In addition, phosphorus resources are abundant, its chemical and electrochemical properties are stable, and it has good sustainability. Finally, it can also solve the problems of dissolution decay and slow kinetics faced by liquid phosphorus negative electrodes.

[0040] (2) The present invention applies phosphorus-based negative electrode materials to all-solid-state lithium batteries, and the adaptability of phosphorus-based negative electrode materials in solid-state battery systems is better than that of liquid systems. In traditional liquid electrolytes, high volume expansion negative electrode materials are prone to pulverization and peeling during the charge and discharge process, resulting in limited cycle performance. In solid-state batteries with a certain compaction effect, the particles of phosphorus-based negative electrode materials can maintain good physical contact, thereby avoiding shedding and improving structural stability. Secondly, the solid electrolyte in the all-solid-state lithium battery has a non-solvent property, which can effectively inhibit the dissolution of lithium polyphosphide intermediates, thereby avoiding the loss of phosphorus active substances. In addition, the solid electrolyte in the all-solid-state lithium battery is non-flowable, which helps to fix the electrolyte-electrode interface and prevent the formation of new interface reaction areas during the charge and discharge process, thereby reducing the frequency of side reactions and improving interface stability.

[0041] (3) The present invention applies phosphorus-based negative electrode materials to all-solid-state lithium batteries, wherein, compared with pure phosphorus negative electrodes (i.e., negative electrodes made of modified phosphorus), phosphorus-based composite negative electrodes (i.e., negative electrodes made of phosphorus / carbon / additive composite materials) have significantly enhanced kinetic performance and excellent chemical-mechanical stability. During the lithiation process, the functional additives can be pre-lithiated to form a mixed ion / electron conductor network, converting the three-phase reaction interface of the phosphorus active material into a more efficient two-phase interface, significantly improving the charge transfer efficiency and reaction rate. During the delithiation process, the presence of the mixed conductor ensures the full delithiation of the lithium-phosphorus alloy, thereby improving the coulombic efficiency. In addition, the functional additives have excellent mechanical properties and low volume expansion characteristics, which can effectively inhibit the pulverization and cracking of the phosphorus active material during the cycle, improve the interface stability, and thus significantly extend the cycle life of the negative electrode.

[0042] (4) The relatively balanced redox potential of the phosphorus-based negative electrode can provide a large overpotential margin, which can effectively avoid the occurrence of lithium metal deposition reaction even under high current conditions, while maintaining a low potential to achieve a higher energy density.

[0043] (5) The present invention uses a dry process to prepare phosphorus-based anode materials and phosphorus-based anodes, which can further enhance their application potential in all-solid-state batteries. This process significantly reduces the use of organic solvents and effectively improves the compatibility between the materials and sulfide-based solid electrolytes. In addition, the dry process helps to achieve uniform dispersion of the various components in the anode, simplifying the battery manufacturing process, reducing the overall preparation cost, and improving the feasibility and consistency of large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0045] Figure 1 This is the XRD pattern of the phosphorus-based negative electrode prepared in Example 1;

[0046] Figure 2 This is an SEM image of the phosphorus-based negative electrode prepared in Example 1;

[0047] Figure 3 This is a charge and discharge curve diagram of the all-solid-state battery prepared in Example 1;

[0048] Figure 4 This is a cycle performance diagram of the all-solid-state battery prepared in Example 1;

[0049] Figure 5 This is a charge and discharge curve diagram of the all-solid-state battery prepared in Example 2;

[0050] Figure 6 This is a charge and discharge curve diagram of the all-solid-state battery prepared in Example 3;

[0051] Figure 7 This is a cycle performance diagram of the all-solid-state battery prepared in Example 4;

[0052] Figure 8 This is a cycle performance diagram of the all-solid-state battery prepared in Example 5;

[0053] Figure 9 This is a charge and discharge curve diagram of the all-solid-state battery prepared in Example 6;

[0054] Figure 10 This is a cycle performance diagram of the all-solid-state battery prepared in Example 6;

[0055] Figure 11 This is a charge and discharge curve diagram of the all-solid-state battery prepared in Example 13;

[0056] Figure 12 This is a cycle performance diagram of the all-solid-state battery prepared in Example 13;

[0057] Figure 13 This is the cycle performance diagram of the all-solid-state battery prepared in Example 14. DETAILED DESCRIPTION

[0058] The technical scheme of the present invention will be clearly and completely described below in conjunction with the accompanying drawings and specific embodiments, but it will be understood by those skilled in the art that the following described embodiments are part of embodiments of the present invention, rather than all embodiments, and are only used to illustrate the present invention, and should not be considered as limiting the scope of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work are within the scope of protection of the present invention. Those who do not specify specific conditions in the embodiments are carried out according to normal conditions or the conditions recommended by the manufacturer. Those whose reagents or instruments are not specified by the manufacturer are conventional products that can be purchased commercially.

[0059] In a first aspect, the present invention provides an application of a phosphorus-based negative electrode material in an all-solid-state lithium battery, wherein the phosphorus-based negative electrode material comprises modified phosphorus and / or a composite material containing the modified phosphorus.

[0060] The present invention has significant advantages in using modified phosphorus and / or composite materials containing modified phosphorus as negative electrodes for all-solid-state lithium batteries. Specifically, phosphorus has a high theoretical specific capacity and a moderate lithiation potential, which not only helps achieve a high energy density for all-solid-state batteries but also effectively inhibits the growth of lithium dendrites, thereby fully realizing its fast charging potential. In addition, phosphorus is abundant in resources, has stable chemical and electrochemical properties, and has good sustainability. It solves the problems of dissolution decay and slow kinetics faced by liquid phosphorus negative electrodes.

[0061] Phosphorus-based negative electrode materials are more adaptable in solid-state battery systems than in liquid systems. In traditional liquid electrolytes, high volume expansion negative electrode materials are prone to pulverization and peeling during the charge and discharge process, resulting in limited cycle performance. In solid-state batteries with a certain compaction effect, the particles of phosphorus-based negative electrode materials can maintain good physical contact, thereby avoiding shedding and improving structural stability. Secondly, the solid electrolyte in all-solid-state lithium batteries has non-solvent properties, which can effectively inhibit the dissolution of lithium polyphosphide intermediates, thereby avoiding the loss of phosphorus active substances. In addition, the solid electrolyte in all-solid-state lithium batteries is non-flowing, which helps to fix the electrolyte-electrode interface and prevent the formation of new interface reaction areas during the charge and discharge process, thereby reducing the frequency of side reactions and improving interface stability.

[0062] In some specific embodiments, the modified phosphorus is mainly prepared by ball milling red phosphorus. By ball milling the red phosphorus, the electrochemical performance of the modified phosphorus is improved, which is conducive to its application in solid-state batteries.

[0063] In some specific embodiments, the modified phosphorus has a particle size distribution of 1 to 10 μm, including but not limited to any of 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, and 10 μm, or a range between any two of these values; preferably, it is 2 to 5 μm. Reducing the particle size distribution of the modified phosphorus helps improve the uniformity of mixing the phosphorus with the carbon material and functional additives, and enhances electrode density.

[0064] In some specific embodiments, the composite material, in addition to the modified phosphorus, further comprises at least one of a carbon material and a functional additive. Specifically, the composite material comprises at least one of a phosphorus / additive composite material, a phosphorus / carbon composite material, and a phosphorus / carbon / additive composite material. The phosphorus / additive composite material comprises modified phosphorus and a functional additive. The phosphorus / carbon composite material comprises modified phosphorus and a carbon material. The phosphorus / carbon / additive composite material comprises modified phosphorus, a carbon material, and a functional additive.

[0065] Among them, compared with pure phosphorus negative electrodes (i.e., negative electrodes made of modified phosphorus), phosphorus-based composite negative electrodes (i.e., negative electrodes made of phosphorus / carbon / additive composite materials) have significantly enhanced kinetic performance and excellent chemical-mechanical stability. During the lithiation process, functional additives can be pre-lithiated to form a mixed ion / electron conductor network, converting the three-phase reaction interface of the phosphorus active material into a more efficient two-phase interface, significantly improving the charge transfer efficiency and reaction rate. During the delithiation process, the presence of the mixed conductor ensures the full delithiation of the lithium-phosphorus alloy, thereby improving the coulombic efficiency. In addition, the functional additives have excellent mechanical properties and low volume expansion characteristics, which can effectively inhibit the pulverization and cracking of the phosphorus active material during the cycle, improve the interface stability, and thus significantly extend the cycle life of the negative electrode.

[0066] In some specific embodiments, the carbon material includes at least one of natural graphite, conductive carbon black Super P (SP), carbon nanotubes, Ketjen black (KB) and hard carbon (HC), more preferably at least one of conductive carbon black Super P and hard carbon.

[0067] In some specific embodiments, the functional additive is a metal additive, specifically including at least one of metal bismuth (Bi), metal antimony (Sb), metal germanium (Ge), metal indium (In), metal tin (Sn) and metal gallium (Ga).

[0068] In some specific embodiments, the functional additive is metal antimony and metal indium in a mass ratio of 1:1 to 2, or metal bismuth and metal tin in a mass ratio of 1:1 to 3, or metal germanium and metal tin in a mass ratio of 1:1 to 3, or metal gallium and metal tin in a mass ratio of 1:1 to 3.

[0069] In some specific embodiments, the mass fraction of the carbon material in the composite material is 3% to 50%, including but not limited to any one of 3%, 5%, 6%, 7%, 8%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, and 50%, or any range therebetween. The use of the above-mentioned amount of carbon material helps to improve the intrinsic electronic conductivity of P and the construction of the electronic conductive network within the electrode.

[0070] In some specific embodiments, the weight fraction of the functional additive in the composite material is 10% to 70%, including but not limited to any of 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, and 70%, or any range therebetween. The use of the functional additive in such amounts helps to build a permeable electron-ion mixed conductor network within the electrode, thereby accelerating the reaction kinetics of P.

[0071] In a second aspect, the present invention provides a phosphorus-based negative electrode material for an all-solid-state lithium battery, wherein the phosphorus-based negative electrode material comprises modified phosphorus and / or a composite material containing the modified phosphorus; wherein the modified phosphorus is mainly prepared by ball milling red phosphorus.

[0072] The advantages of using these phosphorus-based anode materials as anodes for all-solid-state lithium batteries are significant. Phosphorus has a high theoretical specific capacity and a moderate lithiation potential, which not only contributes to the high energy density of all-solid-state batteries but also effectively inhibits the growth of lithium dendrites, thereby fully realizing their fast-charging potential. Furthermore, phosphorus is abundant in resources, has stable chemical and electrochemical properties, and possesses good sustainability. This overcomes the problems of dissolution decay and slow kinetics faced by liquid phosphorus anodes.

[0073] The adaptability of the phosphorus-based negative electrode material provided by the present invention in the solid-state battery system is better than that of the liquid system. In traditional liquid electrolytes, high volume expansion negative electrode materials are prone to pulverization and peeling during the charge and discharge process, resulting in limited cycle performance. In solid-state batteries with a certain compaction effect, the phosphorus-based negative electrode material particles can maintain good physical contact with each other, thereby avoiding the shedding phenomenon and improving structural stability. Secondly, the solid electrolyte in the all-solid-state lithium battery has a non-solvent property, which can effectively inhibit the dissolution of lithium polyphosphide intermediates, thereby avoiding the loss of phosphorus active substances. In addition, the solid electrolyte in the all-solid-state lithium battery is non-flowable, which helps to fix the electrolyte-electrode interface and prevent the formation of new interface reaction areas during the charge and discharge process, thereby reducing the frequency of side reactions and improving interface stability.

[0074] In some specific embodiments, the composite material further comprises at least one of a carbon material and a functional additive in addition to the modified phosphorus, i.e., the composite material comprises one of a phosphorus / additive composite material, a phosphorus / carbon composite material, and a phosphorus / carbon / additive composite material. The phosphorus / additive composite material comprises modified phosphorus and a functional additive, the phosphorus / carbon composite material comprises modified phosphorus and a carbon material, and the phosphorus / carbon / additive composite material comprises modified phosphorus, a carbon material, and a functional additive.

[0075] In some specific embodiments, the carbon material includes at least one of natural graphite, conductive carbon black Super P (SP), carbon nanotubes, Ketjen black (KB) and hard carbon (HC), more preferably at least one of conductive carbon black Super P and hard carbon.

[0076] In some specific embodiments, the functional additive is a metal additive, specifically including at least one of metal bismuth (Bi), metal antimony (Sb), metal germanium (Ge), metal indium (In), metal tin (Sn) and metal gallium (Ga).

[0077] Compared with pure phosphorus anodes (i.e., anodes made of modified phosphorus), phosphorus-based composite anodes (i.e., anodes made of phosphorus / carbon / additive composite materials) have significantly enhanced kinetic performance and excellent chemical-mechanical stability. During the lithiation process, functional additives can be pre-lithiated to form a mixed ion / electron conductor network, converting the three-phase reaction interface of the phosphorus active material into a more efficient two-phase interface, significantly improving the charge transfer efficiency and reaction rate. During the delithiation process, the presence of the mixed conductor ensures the full delithiation of the lithium-phosphorus alloy, thereby improving the coulombic efficiency. In addition, the functional additives have excellent mechanical properties and low volume expansion characteristics, which can effectively inhibit the pulverization and cracking of the phosphorus active material during the cycle, improve the interface stability, and thus significantly extend the cycle life of the anode.

[0078] In some specific embodiments, the functional additive is metal antimony and metal indium in a mass ratio of 1:1 to 2, or metal bismuth and metal tin in a mass ratio of 1:1 to 3, or metal germanium and metal tin in a mass ratio of 1:1 to 3, or metal gallium and metal tin in a mass ratio of 1:1 to 3.

[0079] In some specific embodiments, the mass fraction of the carbon material in the composite material is 3% to 50%, including but not limited to any one of 3%, 5%, 6%, 7%, 8%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50% or a range between any two of them.

[0080] In some specific embodiments, the mass fraction of the functional additive in the composite material is 10% to 70%, including but not limited to any one of 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, and 70%, or a range between any two of them.

[0081] In a third aspect, the present invention provides a method for preparing the above-mentioned phosphorus-based negative electrode material for an all-solid-state lithium battery, comprising the following steps:

[0082] The red phosphorus is subjected to a first ball milling to obtain the modified phosphorus.

[0083] Optionally, the modified phosphorus is mixed with a carbon material by mechanical ball milling and then subjected to a second ball milling to obtain a phosphorus / carbon composite material; or, the modified phosphorus is heat-treated in a gaseous organic carbon source atmosphere by vapor deposition to obtain a phosphorus / carbon composite material.

[0084] Optionally, the modified phosphorus is mixed with a functional additive and then ground to obtain a phosphorus / additive composite material; or, the phosphorus / carbon composite material is mixed with a functional additive and then ground to obtain a phosphorus / carbon / additive composite material.

[0085] Herein, "optionally" means optional or not, that is, when not selected, the preparation method produces modified phosphorus; when selected, the preparation method produces phosphorus / carbon composite materials, and / or phosphorus / additive composite materials, and / or phosphorus / carbon / additive composite materials.

[0086] The present invention provides a dry-process method for preparing phosphorus-based anode materials. This process significantly reduces the use of organic solvents and effectively improves the compatibility of the material with solid electrolytes such as sulfides. Furthermore, the dry-process is simple to operate, has a short process flow, low production costs, and facilitates uniform dispersion of the components.

[0087] In some specific embodiments, the rotation speed of the first ball mill is 400-600 r / min, including but not limited to any one of 400 r / min, 450 r / min, 500 r / min, 550 r / min, and 600 r / min, or a range between any two thereof, preferably 450-550 r / min. The time of the first ball mill is 5-40 h, including but not limited to any one of 5 h, 6 h, 8 h, 12 h, 15 h, 18 h, 20 h, 24 h, 30 h, 26 h, and 40 h, or a range between any two thereof, preferably 15-25 h. Appropriate ball milling speed and time can ensure the uniformity of the particle size of the prepared modified phosphorus. In some specific embodiments, the particle size distribution of the modified phosphorus obtained by ball milling is 1-10 μm, preferably 2-5 μm.

[0088] In some specific embodiments, the rotation speed of the second ball mill is 250-550 r / min, including but not limited to any one of 250 r / min, 300 r / min, 350 r / min, 400 r / min, 450 r / min, 500 r / min, and 550 r / min, or any range between two thereof, preferably 450-550 r / min. The time of the second ball mill is 5-30 h, including but not limited to any one of 5 h, 6 h, 8 h, 12 h, 15 h, 18 h, 20 h, 24 h, and 30 h, or any range between two thereof, preferably 10-20 h.

[0089] In some specific embodiments, the material-to-ball ratio of the second ball mill is 1:30-50, preferably 1:40.

[0090] In some specific embodiments, the second ball milling is performed in a vacuum ball milling tank.

[0091] In some specific embodiments, the gaseous organic carbon source includes at least one of methane, ethylene and acetylene.

[0092] In some specific embodiments, the heat treatment comprises: heating to 400-550°C (e.g., 430°C, 450°C, 480°C, 500°C, or 520°C) at a heating rate of 5-10°C / min (e.g., 6°C / min, 7°C / min, 8°C / min, or 9°C / min) and holding the temperature for 2-10 hours (e.g., 4 hours, 6 hours, or 8 hours). Preferably, heating to 450-500°C at a heating rate of 5-10°C / min and holding the temperature for 4-8 hours.

[0093] In some specific embodiments, the heat treatment is performed in a quartz tubular reactor.

[0094] In some specific embodiments, the temperature is lowered at a rate of 0.5 to 1°C / min during the cooling phase, and the total cooling time is 10 to 20 hours, preferably 15 to 20 hours.

[0095] In some specific embodiments, the protective atmosphere of the heat treatment is a high-purity inert gas (argon or nitrogen).

[0096] In some specific embodiments, the grinding time in preparing the phosphorus / additive composite material and the grinding time in preparing the phosphorus / carbon / additive composite material are each independently 20 to 30 minutes.

[0097] In some specific embodiments, the grinding is performed in a mortar, preferably an agate mortar, and the grinding is performed manually under an argon protective atmosphere.

[0098] In a fourth aspect, the present invention provides a phosphorus-based negative electrode, comprising the above-mentioned phosphorus-based negative electrode material for an all-solid-state lithium battery.

[0099] The more balanced redox potential of the phosphorus-based negative electrode can provide a larger overpotential margin, which can effectively avoid the occurrence of lithium metal deposition reaction even under higher current conditions, while maintaining a lower potential to achieve higher energy density.

[0100] In some specific embodiments, the mass fraction of the phosphorus-based negative electrode material in the phosphorus-based negative electrode is 35% to 80%, including but not limited to any one of 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, and 80%, or any range therebetween. This is beneficial for improving the electrochemical performance of the phosphorus-based negative electrode and the solid-state battery produced therefrom.

[0101] In some specific embodiments, the phosphorus-based negative electrode further includes at least one of a binder, a conductive agent, and an electrolyte.

[0102] In some specific embodiments, the binder includes at least one of polytetrafluoroethylene, styrene-butadiene rubber, polyvinylidene fluoride, polyacrylic acid, polyacrylonitrile and polyacrylamide.

[0103] In some specific embodiments, the mass fraction of the binder in the phosphorus-based negative electrode is 0.1% to 10%.

[0104] In some specific embodiments, the conductive agent includes at least one of carbon nanotubes, Super P, vapor-deposited carbon fibers, and hard carbon.

[0105] In some specific embodiments, the mass fraction of the conductive agent in the phosphorus-based negative electrode is 0.1% to 10%.

[0106] In some specific embodiments, the electrolyte includes at least one of a polymer electrolyte, a sulfide electrolyte, and a halide electrolyte.

[0107] In some specific embodiments, the polymer electrolyte includes at least one of a PVDF-based electrolyte, a PEO-based electrolyte, a PAN-based electrolyte, and a PVC-based electrolyte.

[0108] In some specific embodiments, the sulfide electrolyte includes Li3PS4, Li7P3S 11 、Li6PS5Cl、Li 5.5 PS 4.5 Cl 1.5 、Li 5.5 PS 4.5 ClB r0.5 , Li6PS5Br, Li6PS5I and LBPSI (Li2S-B2S3-P2S5-LiI).

[0109] In some specific embodiments, the halide electrolyte includes Li6YCl3, Li6YBr3, Li6YCl 1.5 Br 1.5 , Li6ScCl3 and Li 0.388 Ta 0.438 La 0.475 At least one of Cl3.

[0110] In some specific embodiments, the mass fraction of the electrolyte in the phosphorus-based negative electrode is 5% to 50%.

[0111] In some specific embodiments, the preparation method of the phosphorus-based negative electrode includes a dry method and / or a wet method.

[0112] In some specific embodiments, the wet method specifically comprises: (1) mixing a phosphorus-based negative electrode material, a binder, a conductive agent, and an electrolyte in a predetermined ratio; (2) adding an organic solvent for dispersion treatment to form a uniform slurry; (3) coating the resulting slurry on the surface of a current collector; and (4) drying to obtain a phosphorus-based negative electrode. Preferably, the solvent is toluene, propane, or a mixture thereof. Preferably, the binder is polyvinylidene fluoride (PVDF). Preferably, the conductive agent is vapor-deposited carbon fiber or Super P (SP).

[0113] In some specific embodiments, the dry process specifically includes: (1) dry mixing a phosphorus-based negative electrode material, a binder, a conductive agent, and an electrolyte; (2) forming a self-supporting film by a rolling process; and (3) hot pressing and laminating the film on the surface of the current collector. Preferably, the binder is polytetrafluoroethylene. Preferably, the conductive agent is vapor-deposited carbon fiber. Preferably, the electrolyte is a sulfide electrolyte.

[0114] The present invention uses a dry process to prepare a phosphorus-based anode material and a phosphorus-based anode, which can further enhance its application potential in all-solid-state batteries. This process significantly reduces the use of organic solvents and effectively improves the compatibility between the material and solid electrolytes such as sulfide-based solid electrolytes. In addition, the dry process helps to achieve uniform dispersion of each component in the anode, simplifies the battery manufacturing process, reduces the overall preparation cost, and improves the feasibility and consistency of mass production.

[0115] In a fifth aspect, the present invention provides an all-solid-state lithium battery including the above-mentioned phosphorus-based anode.

[0116] This all-solid-state lithium battery has a high capacity, a high first-cycle Coulombic efficiency, and good cycling performance.

[0117] In some specific embodiments, the all-solid-state lithium battery further includes a solid electrolyte layer and a cathode layer in addition to the above-mentioned phosphorus-based anode.

[0118] In some specific embodiments, the solid electrolyte in the solid electrolyte layer includes at least one of a halide-based electrolyte, a sulfide-based electrolyte, a polymer-based electrolyte, and an organic-inorganic composite electrolyte. Preferably, the solid electrolyte in the solid electrolyte layer is a sulfide electrolyte with a chemical formula of xLi2S-yP2S5 (x:y = 70:30), Li 7-x PS 6-x X x (X is one or more of F, Cl, Br, I, and x = 0.8 - 2.0), Li2S-B2S3-P2S5-LiI (LBPSI). More preferably, the solid electrolyte in the solid electrolyte layer is Li 7-x PS 6-x sCl x (x = 1.0 - 1.5).

[0119] In some specific embodiments, the cathode active material in the cathode layer includes at least one of lithium iron phosphate (LiFePO4), lithium cobalt oxide (LiCoO2), ternary materials (LiNi x Co x Mn 1-2x O2, 0 < x < 0.5), and lithium-rich materials (xLi\(_2\)MnO\(_3\)·(1 - x)LiMO\(_2\), M is one or more of Ni, Co, Mn).

[0120] In some specific embodiments, the mass fraction of the cathode active material in the cathode layer is 60% - 90%.

[0121] In some specific embodiments, the positive electrode layer includes, in addition to the positive electrode active material, a binder, a conductive agent, an electrolyte, and a current collector. The binder may be, for example, PTFE. The conductive agent may be, for example, vapor-deposited carbon fiber. The electrolyte is the same as that used in the solid electrolyte layer.

[0122] The embodiments of the present invention will be described in detail below with reference to the examples, but it will be understood by those skilled in the art that the following examples are merely illustrative of the present invention and should not be construed as limiting the scope of the invention. Where specific conditions are not specified in the examples, the methods were performed according to conventional conditions or the conditions recommended by the manufacturer. Where the manufacturers of the reagents or instruments are not specified, they are all commercially available conventional products.

[0123] Example 1

[0124] The preparation method of the phosphorus-based negative electrode material provided in this embodiment comprises the following steps: (1) placing red phosphorus in a vacuum ball mill and ball milling at a speed of 550 r / min for 18 hours (i.e., the first ball milling) to obtain modified phosphorus with a particle size distribution of 2 to 5 μm. (2) mixing the modified phosphorus with conductive carbon black Super P (carbon material, SP) at a mass ratio of 7:3 and ball milling at a speed of 500 r / min for 15 hours in a vacuum ball mill (i.e., the second ball milling) to obtain a phosphorus / carbon composite material. (3) using an agate mortar, mixing the phosphorus / carbon composite material and metal Sb (functional additive) at a mass ratio of 1:1 and manually grinding for 25 minutes under an argon protective atmosphere to obtain a phosphorus / Super P / additive composite material (i.e., a phosphorus / carbon / additive composite material, wherein the mass fraction of the functional additive is 50% and the mass fraction of the carbon material is 15%).

[0125] The preparation method of the all-solid-state lithium battery provided in this embodiment comprises the following steps: (1) weighing 100 mg of LPSC 1.5 Solid electrolyte powder, apply 100MPa pressure and maintain for 1 minute to obtain solid electrolyte sheet. (2) Phosphorus / Super P / additive composite material with a mass ratio of 1:1 and LPSC 1.5 After the mixture is evenly mixed, it is spread on one side of the solid electrolyte sheet, and a pressure of 370 MPa is applied and maintained for 3 minutes to obtain a phosphorus-based negative electrode (i.e., the mass fraction of the phosphorus-based negative electrode material in the phosphorus-based negative electrode is 50%). (3) A lithium-indium alloy is attached to the other side of the solid electrolyte sheet, and a pressure of 120 MPa is applied and maintained for 1 minute to finally obtain an all-solid-state lithium battery containing a phosphorus-based negative electrode.

[0126] The structure of the all-solid-state battery prepared in this embodiment 1 is LiIn|LPSC 1.5 |P / SP / Sb-LPSC 1.5The XRD pattern and SEM pattern of the phosphorus-based negative electrode prepared in Example 1 are as follows: Figure 1 and Figure 2 See Figure 1 The components in the phosphorus-based negative electrode showed good chemical stability (SP had no characteristic peak). Figure 2 It is further shown that modified phosphorus, Sb functional additives and LPSC 1.5 The particle size of the electrolyte particles is concentrated in the range of 2 to 5 μm. The electrochemical performance of the all-solid-state battery prepared in Example 1 was tested at 25°C and 40 MPa pressure. Figure 3 At C / 5 rate, the first discharge capacity reaches 1517mAh·g -1 , the first cycle Coulombic efficiency is as high as 92%, indicating that the material has excellent reversibility. Figure 4 At a rate of 1C, the battery can stably cycle 1000 times with a capacity retention rate close to 100%, reflecting the excellent cycle stability of the phosphorus-based negative electrode.

[0127] Example 2

[0128] The preparation method of the phosphorus-based negative electrode material provided in this embodiment is basically the same as that in Example 1, except that in step (2), the conductive carbon black Super P is replaced by hard carbon (HC) of equal mass.

[0129] An all-solid-state lithium battery was prepared using the phosphorus-based negative electrode material prepared in this example and according to the preparation method of the all-solid-state lithium battery in Example 1.

[0130] The structure of the all-solid-state battery prepared in Example 2 is LiIn|LPSC 1.5 |P / HC / Sb-LPSC 1.5 The test conditions are the same as in Example 1, see Figure 5 The all-solid-state battery prepared in this embodiment has an initial discharge capacity of 1483 mAh g at a C / 2 rate. -1 , the first-cycle coulombic efficiency is 87%. Compared with Example 1, the capacity and efficiency of the all-solid-state battery prepared in Example 2 are lower, mainly because hard carbon (HC) has lower electronic conductivity than conductive carbon black (SP).

[0131] Example 3

[0132] The preparation method of the phosphorus-based negative electrode material provided in this embodiment is basically the same as that in Example 1, except that: in step (3), the mass ratio of the phosphorus / carbon composite material and the metal Sb is replaced with 7:3 (that is, in the phosphorus / carbon / additive composite material, the mass fraction of the functional additive is 30%, and the mass fraction of the carbon material is 21%).

[0133] The preparation method of the all-solid-state lithium battery provided in this embodiment is basically the same as that in embodiment 1, except that the phosphorus-based negative electrode material prepared in this embodiment is used (replacing the phosphorus-based negative electrode material prepared in embodiment 1), and in step (2), the LPSC 1.5 Replaced with LBPSI of equal quality.

[0134] The structure of the all-solid-state battery prepared in Example 3 is LiIn|LPSC 1.5 |P / SP-Sb-LBPSI. Test conditions are the same as in Example 1, see Figure 6 The all-solid-state battery prepared in Example 3 has an initial discharge capacity of 1751 mAh·g at a C / 5 rate. -1 The first-cycle coulombic efficiency is 87%. Compared with Example 1, the capacity of the all-solid-state battery prepared in Example 3 is improved. This is attributed to the LBPSI electrolyte participating in the reaction and thus providing part of the capacity. At the same time, the higher coulombic efficiency indicates that the negative electrode active material has good reversibility.

[0135] Example 4

[0136] The preparation method of the phosphorus-based negative electrode material provided in this embodiment is the same as that in Example 1.

[0137] The preparation method of the all-solid-state lithium battery provided in this embodiment is basically the same as that in Example 1, except that: step (3) is: lithium cobalt oxide (LiCoO2, abbreviated as LCO) positive electrode material powder is evenly spread on the other side of the solid electrolyte sheet (N / P ratio is 1.1), 370 MPa pressure is applied and maintained for 3 minutes, and finally an all-solid-state lithium battery containing a phosphorus-based negative electrode is obtained.

[0138] The structure of the all-solid-state battery prepared in Example 4 is P / SP-Sb-LPSC 1.5 |LPSC 1.5 |LCO. Test conditions are the same as in Example 1, see Figure 7 The all-solid-state battery prepared in Example 4 was subjected to 7.5 mAh·cm -2 The first cycle discharge capacity was 5.63 mAh cm -2 After 200 cycles, the capacity retention rate was 84%, showing excellent cycle stability.

[0139] Example 5

[0140] The preparation method of the phosphorus-based negative electrode material provided in this embodiment is the same as that in Example 3.

[0141] The preparation method of the all-solid-state lithium battery provided in this embodiment is basically the same as that in Example 3, except that: step (3) is: lithium cobalt oxide (LiCoO2, abbreviated as LCO) positive electrode material powder is evenly spread on the other side of the solid electrolyte sheet (N / P ratio is 1.1), 370 MPa pressure is applied and maintained for 3 minutes, and finally an all-solid-state lithium battery containing a phosphorus-based negative electrode is obtained.

[0142] The structure of the all-solid-state battery prepared in Example 5 is P / SP-Sb-LBPSI|LPSC 1.5 |LCO. The all-solid-state battery prepared in Example 5 was tested at 25°C and 40 MPa at a C / 2 rate. Figure 8 As shown, the first cycle discharge capacity is 106mAh·g -1 , the capacity retention rate was 80% after 1000 cycles. The results show that LBPSI electrolyte helps to alleviate the capacity decay caused by the chemical-mechanical effect of the negative electrode during the cycle.

[0143] Example 6

[0144] The preparation method of the phosphorus-based negative electrode material provided in this embodiment is the same as that in Example 1.

[0145] The preparation method of the all-solid-state lithium battery provided in this embodiment is basically the same as that in embodiment 1, except that: the phosphorus-based negative electrode material prepared in this embodiment is used (replacing the phosphorus-based negative electrode material prepared in embodiment 1), and step (2) is: mixing the phosphorus / Super P / additive composite material with a mass ratio of 1:1 and the LPSC 1.5 (electrolyte) is mixed to obtain a composite powder material, a PTFE binder accounting for 1% by mass is added to the composite powder material, and after mixing evenly, it is repeatedly rolled to obtain a phosphorus-based negative electrode membrane, and then the phosphorus-based negative electrode membrane is cut into discs with a diameter of 9 mm with a pistol and attached to one side of the solid electrolyte sheet; at the same time, step (3) is: lithium cobalt oxide (LiCoO2, abbreviated as LCO) positive electrode material powder is evenly mixed with a PTFE binder accounting for 1% by mass and repeatedly rolled to obtain an LCO positive electrode membrane, and then the LCO positive electrode membrane is cut into discs with a diameter of 9 mm with a pistol and attached to the other side of the solid electrolyte sheet (N / P ratio is 1.1), and a pressure of 370 MPa is applied and maintained for 3 minutes to finally obtain an all-solid-state lithium battery containing a phosphorus-based negative electrode.

[0146] The structure of the all-solid-state battery prepared in Example 6 is P / SP-Sb-LPSC 1.5 film|LPSC 1.5 |LCO film, tested at 60℃ and 40MPa, such as Figure 9 As shown, the first charge capacity of the battery at C / 2 rate is 177 mAh g -1, the first-cycle Coulombic efficiency is 86%; Figure 10 It shows that it can be stably cycled for 500 cycles at a 5C rate with a capacity retention rate of about 80%. This shows that the phosphorus-based negative electrode prepared by the dry film formation process also has good cycle stability.

[0147] Example 7

[0148] The preparation method of the phosphorus-based negative electrode material provided in this embodiment is basically the same as that in Example 1, except that: in step (3), the functional additive (metal Sb) is replaced by metal bismuth and metal tin in a mass ratio of 1:3 (the mass ratio of the phosphorus / carbon composite material to the functional additive remains unchanged).

[0149] An all-solid-state lithium battery was prepared using the phosphorus-based negative electrode material prepared in this example and according to the preparation method of the all-solid-state lithium battery in Example 1.

[0150] Example 8

[0151] The preparation method of the phosphorus-based negative electrode material provided in this embodiment is basically the same as that in Example 1, except that: step (1) is: placing red phosphorus in a vacuum ball mill and ball milling it at a speed of 400 r / min for 20 h (i.e., the first ball milling) to obtain modified phosphorus with a particle size distribution of 6 to 10 μm.

[0152] An all-solid-state lithium battery was prepared using the phosphorus-based negative electrode material prepared in this example and according to the preparation method of the all-solid-state lithium battery in Example 1.

[0153] Example 9

[0154] The preparation method of the phosphorus-based negative electrode material provided in this embodiment includes the following steps: (1) placing red phosphorus in a vacuum ball mill and ball milling at a speed of 500 r / min for 24 hours (i.e., the first ball milling) to obtain modified phosphorus with a particle size distribution of 2 to 5 μm. (2) mixing the modified phosphorus with carbon nanotubes (carbon material) at a mass ratio of 2:1 and ball milling at a speed of 500 r / min for 15 hours in a vacuum ball mill (i.e., the second ball milling) to obtain a phosphorus / carbon composite material. (3) using an agate mortar, mixing the phosphorus / carbon composite material at a mass ratio of 4:1 and a functional additive (metal antimony and metal indium at a mass ratio of 1:2) and manually grinding for 30 minutes under an argon protective atmosphere to obtain a phosphorus / carbon / additive composite material (i.e., in the phosphorus / carbon / additive composite material, the mass fraction of the functional additive is 20% and the mass fraction of the carbon material is 26.7%).

[0155] An all-solid-state lithium battery was prepared using the phosphorus / carbon / additive composite material prepared in this example and according to the preparation method of the all-solid-state lithium battery in Example 1.

[0156] Example 10

[0157] The preparation method of the phosphorus-based negative electrode material provided in this embodiment is basically the same as that in Example 9, except that in step (2), the carbon nanotubes are replaced with an equal mass of Ketjen black.

[0158] An all-solid-state lithium battery was prepared using the phosphorus / carbon / additive composite material prepared in this example and according to the preparation method of the all-solid-state lithium battery in Example 1.

[0159] Example 11

[0160] The preparation method of the phosphorus-based negative electrode material provided in this embodiment is basically the same as that in Example 9, except that the mass ratio of modified phosphorus to carbon nanotubes in step (2) is changed to 5:4, and the mass ratio of phosphorus / carbon composite material to functional additive in step (3) is replaced to 9:1 (i.e., in the phosphorus / carbon / additive composite material, the mass fraction of the functional additive is 10%, and the mass fraction of the carbon material is 40%).

[0161] An all-solid-state lithium battery was prepared using the phosphorus / carbon / additive composite material prepared in this example and according to the preparation method of the all-solid-state lithium battery in Example 1.

[0162] Example 12

[0163] The preparation method of the phosphorus-based negative electrode material provided in this embodiment includes the following steps: (1) placing red phosphorus in a vacuum ball mill and ball milling at a speed of 530r / min for 20h (i.e., the first ball milling) to obtain modified phosphorus with a particle size distribution of 2 to 5μm. (2) heating the modified phosphorus to 500℃ at a heating rate of 8℃ / min in an acetylene atmosphere of a gaseous organic carbon source, keeping the temperature for 8h and then cooling to obtain a phosphorus / carbon composite material. (3) using an agate mortar, mixing the phosphorus / carbon composite material and metal Ga (functional additive) in a mass ratio of 1:1, and then manually grinding for 20min under an argon protective atmosphere to obtain a phosphorus / carbon / additive composite material. In the phosphorus / carbon / additive composite material prepared in this embodiment, the mass fraction of carbon material is 5%, and the mass fraction of functional additive is 50%.

[0164] An all-solid-state lithium battery was prepared using the phosphorus-based negative electrode material prepared in this example and according to the preparation method of the all-solid-state lithium battery in Example 1.

[0165] Example 13

[0166] The phosphorus-based negative electrode material provided in this embodiment is the phosphorus / carbon composite material prepared in step (2) of Example 1.

[0167] An all-solid-state lithium battery was prepared using the phosphorus-based negative electrode material prepared in this example and according to the preparation method of the all-solid-state lithium battery in Example 1.

[0168] The structure of the all-solid-state battery prepared in Example 13 is LiIn|LPSC 1.5 |P / SP-LPSC 1.5 The test conditions are the same as in Example 1, see Figure 11 At C / 5 rate, the first discharge capacity is 2379 mAh·g -1 , the first cycle coulombic efficiency is only 83%. The first cycle coulombic efficiency of the all-solid-state battery prepared in this embodiment is lower than that of Example 1, which may be due to the decrease in charge transfer efficiency leading to a decrease in the reversibility of the active material; and, see Figure 12 The all-solid-state battery prepared in this embodiment was cycled 200 times at a rate of 1C, and the capacity retention rate was 55%, indicating that the lack of functional additives will affect the cycle stability of phosphorus-based negative electrode materials.

[0169] Example 14

[0170] The phosphorus-based negative electrode material provided in this embodiment is the phosphorus / carbon composite material prepared in step (2) of Example 4.

[0171] An all-solid-state lithium battery was prepared using the phosphorus-based negative electrode material prepared in this example and according to the preparation method of the all-solid-state lithium battery in Example 4.

[0172] The structure of the all-solid-state battery prepared in Example 14 is P / SP-LPSC 1.5 |LPSC 1.5 |LCO. Test conditions are 25℃, 40MPa, see Figure 13 , with a loading of 7.6 mAh·cm -2 Under the C / 2 rate, the first cycle discharge capacity is 3.92mAh·cm -2 , after 100 cycles, the capacity retention rate was only 51%, which further verified that the lack of functional additives has a significant insufficiency in cycle stability.

[0173] Comparative Example 1

[0174] The phosphorus-based negative electrode material provided in this comparative example is unmilled red phosphorus, and its particle size distribution is 10 to 30 μm.

[0175] An all-solid-state lithium battery was prepared by using the phosphorus-based negative electrode material of this comparative example and following the preparation method of the all-solid-state lithium battery of Example 1.

[0176] Comparative Example 2

[0177] The phosphorus-based negative electrode material prepared in Example 1 was used to prepare a liquid lithium-ion battery according to the following method: the phosphorus-based negative electrode material prepared in Example 1 and polyvinylidene fluoride were mixed in a mass ratio of 95:5, and an appropriate amount of N-methylpyrrolidone was added to prepare a slurry. The slurry was coated on copper foil, dried, and cut to obtain a negative electrode.-1 A liquid lithium-ion battery was assembled using a solution of LiPF6 ethylene carbonate and dimethyl carbonate in a volume ratio of 1:1 as the electrolyte, a PE film as the battery separator, and lithium metal as the counter electrode.

[0178] The electrochemical performance test results of the batteries of Examples 7 to 13 and Comparative Examples 1 and 2 are shown in Table 1.

[0179] Table 1 Electrochemical detection results of Examples 7 to 13 and Comparative Examples 1 to 2

[0180]

[0181] In summary, the present invention has significant advantages in using modified phosphorus and / or composite materials containing modified phosphorus as the negative electrode of all-solid-state lithium batteries. Phosphorus has a high theoretical specific capacity and a moderate lithiation potential, which not only helps to achieve the high energy density of all-solid-state batteries, but also effectively inhibits the growth of lithium dendrites, thereby fully realizing its potential for fast charging. In addition, phosphorus resources are abundant, its chemical and electrochemical properties are stable, and it has good sustainability. It solves the problems of dissolution decay and slow kinetics faced by liquid phosphorus negative electrodes.

[0182] Furthermore, compared with pure phosphorus negative electrodes (i.e., negative electrodes made of modified phosphorus), phosphorus-based composite negative electrodes (i.e., negative electrodes made of phosphorus / carbon / additive composite materials) have significantly enhanced kinetic performance and excellent chemical-mechanical stability. During the lithiation process, functional additives can be pre-lithiated to form a mixed ion / electron conductor network, converting the three-phase reaction interface of the phosphorus active material into a more efficient two-phase interface, significantly improving the charge transfer efficiency and reaction rate. During the delithiation process, the presence of the mixed conductor ensures the full delithiation of the lithium-phosphorus alloy, thereby improving the coulombic efficiency. In addition, the functional additives have excellent mechanical properties and low volume expansion characteristics, which can effectively inhibit the pulverization and cracking of the phosphorus active material during the cycle, improve the interface stability, and thus significantly extend the cycle life of the negative electrode.

[0183] Although the present invention has been illustrated and described using specific embodiments, it should be appreciated that the above embodiments are merely intended to illustrate the technical solutions of the present invention rather than to limit them. Those skilled in the art should understand that the technical solutions described in the above embodiments may be modified, or some or all of the technical features thereof may be replaced by equivalents, without departing from the spirit and scope of the present invention. However, these modifications or replacements do not deviate from the essence of the corresponding technical solutions within the scope of the technical solutions of the embodiments of the present invention. Therefore, this means that all such replacements and modifications within the scope of the present invention are included in the appended claims.

Claims

1. Application of phosphorus-based negative electrode materials in all-solid-state lithium batteries, characterized in that: The phosphorus-based negative electrode material includes modified phosphorus and / or a composite material containing the modified phosphorus.

2. The use of the phosphorus-based negative electrode material in an all-solid-state lithium battery according to claim 1, characterized in that: The modified phosphorus is mainly prepared by ball milling red phosphorus; Preferably, the particle size distribution of the modified phosphorus is 1 to 10 μm, more preferably 2 to 5 μm.

3. The use of the phosphorus-based negative electrode material in an all-solid-state lithium battery according to claim 1, characterized in that: The composite material includes, in addition to the modified phosphorus, at least one of a carbon material and a functional additive; Preferably, the carbon material comprises at least one of natural graphite, Super P, carbon nanotubes, Ketjen black and hard carbon; Preferably, the functional additive includes at least one of metal bismuth, metal antimony, metal germanium, metal indium, metal tin and metal gallium; Preferably, the mass fraction of the carbon material in the composite material is 3% to 50%; Preferably, the mass fraction of the functional additive in the composite material is 10% to 70%.

4. A phosphorus-based negative electrode material for an all-solid-state lithium battery, characterized in that: The phosphorus-based negative electrode material includes modified phosphorus and / or a composite material containing the modified phosphorus; wherein the modified phosphorus is mainly prepared by ball milling red phosphorus.

5. The phosphorus-based negative electrode material for an all-solid-state lithium battery according to claim 4, characterized in that: The composite material includes, in addition to the modified phosphorus, at least one of a carbon material and a functional additive; Preferably, the carbon material comprises at least one of natural graphite, Super P, carbon nanotubes, Ketjen black and hard carbon; Preferably, the functional additive includes at least one of metal bismuth, metal antimony, metal germanium, metal indium, metal tin and metal gallium; Preferably, the mass fraction of the carbon material in the composite material is 3% to 50%; Preferably, the mass fraction of the functional additive in the composite material is 10% to 70%.

6. The method for preparing a phosphorus-based negative electrode material for an all-solid-state lithium battery according to any one of claims 4 to 5, characterized in that: The steps include: performing a first ball milling on red phosphorus to obtain the modified phosphorus; Optionally, the modified phosphorus is mixed with a carbon material and then subjected to a second ball milling to obtain a phosphorus / carbon composite material; or, the modified phosphorus is heat-treated in a gaseous organic carbon source atmosphere to obtain a phosphorus / carbon composite material; Optionally, the modified phosphorus is mixed with a functional additive and then ground to obtain a phosphorus / additive composite material; Alternatively, the phosphorus / carbon composite material is mixed with a functional additive and then ground to obtain a phosphorus / carbon / additive composite material.

7. The method for preparing a phosphorus-based negative electrode material for an all-solid-state lithium battery according to claim 6, wherein: At least one of the following conditions is met: (1) The rotation speed of the first ball mill is 400 to 600 r / min, and the time of the first ball mill is 5 to 40 hours; (2) The rotation speed of the second ball mill is 250 to 550 r / min, and the time of the second ball mill is 5 to 30 hours; (3) The gaseous organic carbon source includes at least one of methane, ethylene and acetylene; (4) The heat treatment comprises: heating to 400-550°C at a heating rate of 5-10°C / min and keeping the temperature for 2-10 hours; (5) The grinding time is 20 to 30 minutes.

8. A phosphorus-based negative electrode, characterized in that The invention comprises the phosphorus-based negative electrode material for an all-solid-state lithium battery as claimed in any one of claims 4 to 5.

9. The phosphorus-based negative electrode according to claim 8, characterized in that The mass fraction of the phosphorus-based negative electrode material in the phosphorus-based negative electrode is 35% to 80%; Preferably, the phosphorus-based negative electrode further includes at least one of a binder, a conductor and an electrolyte.

10. An all-solid-state lithium battery, characterized in that: Comprising the phosphorus-based negative electrode as claimed in claim 9.

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