CN116072863A

CN116072863A - Composite negative electrode material, negative electrode plate, secondary battery and electronic equipment

Info

Publication number: CN116072863A
Application number: CN202111277979.3A
Authority: CN
Inventors: 兰丹妮; 洪响
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2021-10-30
Filing date: 2021-10-30
Publication date: 2023-05-05

Abstract

The embodiment of the application provides a composite anode material, which comprises a black phosphorus material, a stabilizer and a carbon material, wherein at least part of the stabilizer is distributed on the surface of the black phosphorus material, the stabilizer is a material which can react with the black phosphorus material to form a chemical bond with bond energy larger than P-C bond energy, the band gap of the stabilizer is smaller than 3eV, and the lithium ion diffusion coefficient is larger than 10 ^‑12 cm ² And/s. By introducing the stabilizer which has good electron conductivity and ion conductivity and can form a strong chemical bond with the black phosphorus, the problems of easy collapse of a conductive network and the like caused by the expansion of the black phosphorus material can be effectively reduced, the side reaction failure phenomenon of a charge and discharge product of the black phosphorus can be slowed down, and the circulation stability of the black phosphorus material can be obviously improved. The application also providesA negative electrode tab, a secondary battery, and an electronic device are provided.

Description

Composite negative electrode material, negative electrode plate, secondary battery and electronic equipment

Technical Field

The embodiment of the application relates to the technical field of secondary batteries, in particular to a composite negative electrode material, a negative electrode plate, a secondary battery and electronic equipment.

Background

The continuous development of electronic devices such as mobile phones, tablet computers, electric automobiles and the like puts higher demands on the energy density and power density of secondary batteries, while the energy density of lithium ion batteries based on traditional graphite cathodes is close to ceilings, and the ever-increasing standby and cruising demands of people cannot be met. Black phosphorus is considered as a battery negative electrode material that is highly likely to achieve both high energy density and fast charge performance due to its high theoretical specific capacity (approximately 7 times that of graphite), extremely low lithium ion diffusion energy barrier (about 0.05 eV), and relatively high electron conductivity (300S/m).

However, black phosphorus expands in volume during charge and discharge, and has poor cycle stability, and its charge and discharge intermediate products (such as lithium phosphide) are unstable in the electrolyte (such as easy dissolution failure, occurrence of side reaction, etc.), resulting in rapid decay of battery capacity. At present, the proposal for improving the problems is to compound black phosphorus and carbon materials to prepare a phosphorus-carbon composite material, but the combination between phosphorus and carbon is weaker, the volume expansion of the black phosphorus in the charge-discharge process can cause the unstable conductive network structure of the phosphorus-carbon composite material, the improvement of the circulation stability is limited, and the side reaction problem of a black phosphorus charge-discharge intermediate product and electrolyte is not solved effectively.

Disclosure of Invention

In view of this, the embodiment of the present application provides a black phosphorus-based composite anode material, by introducing a stabilizer that has good electron conductivity and ion conductivity and can form a strong chemical bond with black phosphorus, so as to effectively solve both the negative problem caused by expansion of black phosphorus and the problem of unstable charge and discharge products.

The first aspect of the present embodiment provides a composite anode material, which includes a black phosphorus material, a stabilizer and a carbon material, at least a part of the stabilizer is distributed on the surface of the black phosphorus material, the stabilizer is a material capable of forming a chemical bond with a bond energy greater than a P-C bond energy with the black phosphorus material, the band gap of the stabilizer is less than 3eV, and the lithium ion diffusion coefficient is greater than 10 ^-12 cm ² /s。

According to the composite anode material provided by the embodiment of the application, the stabilizer is introduced on the basis of the black phosphorus and the carbon material, the stabilizer has good electronic conductivity and ion conduction capacity, and at least part of the stabilizer is distributed on the surface of the black phosphorus material, so that the stabilizer is connected with the black phosphorus material through stronger chemical bonds, the carbon material can also be connected with the black phosphorus material through chemical bonds, the black phosphorus material can stably penetrate into a composite conductive network formed by the carbon material and the stabilizer, the effective transmission of electrons and ions in the composite anode material is better ensured by introducing the stabilizer, and the defects of insufficient conductivity and poor ion conductivity when the carbon material is simply introduced are overcome. And based on the strong binding force between the stabilizer and the black phosphorus, even if the black phosphorus swells to cause the rupture of chemical bonds between the black phosphorus and carbon, electrons/ions can still be transmitted to each black phosphorus material through the stabilizer, so that the normal exertion of the black phosphorus multiplying power performance is ensured. In addition, the strong binding force of the stabilizer and the black phosphorus also enables the acting force of the charge and discharge products of the black phosphorus and the stabilizer to be strong, so that the cohesion of the charge and discharge products of the composite anode material is stronger than the interaction between the charge and discharge products and the electrolyte solvent, the charge and discharge products are difficult to dissolve/react by the solvent, and irreversible attenuation of the battery capacity is avoided. Therefore, the composite anode material can fully exert the high specific capacity and quick charge characteristic of black phosphorus, and can also give consideration to durable cycle stability and the like.

In this embodiment, the stabilizer includes one or more of aluminum, tin, bismuth, antimony, germanium, alloys thereof, tin selenide, and doped lithium titanate, lithium thiophosphate, aluminum oxide, tin oxide, transition metal oxide.

In some embodiments of the present application, the doping element contained in the lithium titanate includes one or more of Li, ti, N, P, C, F, cl, br, al, mg, ca, sr, ba, ag, cu, sn, ni, mo, co, cr, zr, V, ta, la, sm; the doping elements contained in the lithium thiophosphate comprise one or more of Al, mg, ca, sr, ba, sc, ga, in, nb, ta and V; the doping elements contained in the aluminum oxide, the tin oxide and the transition metal oxide comprise one or more of metal elements, transition metal elements and nonmetal elements.

In some embodiments of the present application, the stabilizer comprises one or more of aluminum, tin, bismuth, antimony, germanium, selenium-antimony alloy, selenium-germanium alloy, tin selenide, and doped element-containing lithium titanate, lithium thiophosphate, titanium-niobium oxide, vanadium oxide, titanium oxide. These stabilizer materials can form chemical bonds with large bond energy with black phosphorus, and have better conductivity and ion conductivity.

In the embodiment of the application, the mass ratio of the black phosphorus material in the composite anode material is 50% -90%. The black phosphorus material with high theoretical specific capacity has high quality, and can ensure that the composite anode material can better exert the characteristic of high specific capacity.

In the embodiment of the application, the mass ratio of the carbon material in the composite anode material is 2% -48%. Proper amount of carbon material can ensure good dispersibility of the black phosphorus material and the stabilizer and ensure structural stability of the composite anode material.

In the embodiment of the application, the mass ratio of the stabilizer in the composite anode material is 2% -48%. The mass ratio can ensure that enough stabilizer forms bonds with the black phosphorus material and the ionic and electronic conductivity of the composite anode material is higher.

In order to better ensure that more stabilizer can contact the surface of the black phosphorus material and ensure the high capacity performance of the whole composite anode material, in some embodiments of the application, the mass of the stabilizer is 4% -53% of the mass of the black phosphorus material.

In some embodiments of the present application, the carbon material encapsulates the black phosphorus material and the stabilizer. The carbon material can also block the reaction between the charge and discharge products of the black phosphorus material and the electrolyte, inhibit the volume expansion of the black phosphorus material, and facilitate the formation of a composite conductive network with the stabilizer.

In the embodiment of the application, the thickness of the carbon material layer wrapping the black phosphorus material and the stabilizer is 1nm-1000nm.

In this embodiment, the stabilizer is distributed in the black phosphorus material, and/or the surface of the black phosphorus material particles is coated with the stabilizer.

In the embodiment of the application, the stabilizer forms a stabilizer coating layer with the thickness of 1nm-1000nm on the surface of the black phosphorus material particles.

In this embodiment, the carbon material includes one or more of artificial graphite, natural graphite, graphene, carbon nanotubes, carbon fibers, mesophase carbon microspheres, carbon black, pyrolytic carbon, and activated carbon.

A second aspect of the embodiments provides a negative electrode tab, which includes a negative electrode current collector and a negative electrode material layer disposed on the negative electrode current collector, where the negative electrode material layer includes the composite negative electrode material and the binder according to the first aspect of the embodiments.

In some embodiments of the present application, the anode material layer further includes other anode active components, where the other anode active components include one or more of lithium titanate, carbon-based materials, silicon-based materials, tin-based materials, germanium-based materials, antimony-based materials, and bismuth-based materials.

The third aspect of the embodiment of the application also provides a secondary battery, which comprises the negative electrode plate of the second aspect of the embodiment of the application. The secondary battery may be a lithium secondary battery.

The composite anode material is used as an anode active material of a secondary battery, so that the cycle stability, specific capacity and quick charge performance of the secondary battery can be improved, and the requirements of consumer electronic equipment on long cycle life, high energy density and short charging time of the secondary battery can be better met.

A fourth aspect of the embodiments of the present application provides an electronic device, which includes the secondary battery according to the third aspect of the present application. This electronic equipment through adopting the secondary cell power supply that this application embodiment provided, can promote the use experience and the market competition of product.

Drawings

Fig. 1a and 1b are schematic structural diagrams of several exemplary composite anode materials according to embodiments of the present application.

Fig. 1c is a schematic structural diagram of a secondary particle formed by the primary particles of fig. 1a according to an embodiment of the present application.

Fig. 2 is a composite structure formed by the composite anode material and other anode active materials according to the embodiment of the present application.

Fig. 3 is a schematic structural view of a lithium secondary battery provided in an embodiment of the present application.

Fig. 4 is a schematic structural diagram of an electronic device according to an embodiment of the present application.

Fig. 5 is a schematic structural diagram of another electronic device according to an embodiment of the present application.

Detailed Description

The embodiments of the present application will be described in detail below with reference to the accompanying drawings in the embodiments of the present application.

Referring to fig. 1a and fig. 1b, schematic structural diagrams of a composite anode material 100 according to some embodiments of the present application are shown. The composite anode material 100 comprises a black phosphorus material 10, a stabilizer 20 and a carbon material 30, wherein at least a part of the stabilizer 20 is distributed on the surface of the black phosphorus material 10, the stabilizer 20 is a material capable of forming a chemical bond with the black phosphorus material 10 with bond energy larger than P-C bond energy, the band gap of the stabilizer 20 is smaller than 3eV, and the lithium ion diffusion coefficient is larger than 1 x 10 ^-12 cm ² /s。

The stabilizer 20 with good electron conductivity (band gap is less than 3 eV) and good ion conduction capability is introduced into the composite anode material 100, and can form a composite conductive network together with the carbon material 30, so that effective transmission of electrons and ions in the composite anode material 100 is ensured, the defects of insufficient conductivity and poor ion conductivity caused by simply introducing the carbon material into the black phosphorus material are overcome, the black phosphorus material 10 can be loaded in the composite conductive network, the composite conductive network has a certain binding effect on black phosphorus, and the composite conductive network also has the effect of slowing down the expansion stress of the black phosphorus in the battery cycle process.

In addition, since at least a portion of the stabilizer 20 is distributed on the surface of the black phosphorus material 10, and the stabilizer 20 has the capability of forming a stronger bond with the black phosphorus material 10, so that the black phosphorus material 10 is connected with the stabilizer 20 through a chemical bond, and of course, the stabilizer can also be connected with the carbon material 30 through a chemical bond, so that the adhesion of the black phosphorus material on the composite conductive network is further enhanced, and even if the volume expansion of the black phosphorus occurs during the charge and discharge of the battery to cause the rupture of the chemical bond (such as P-C bond) between the black phosphorus and carbon, the stabilizer 20 is still connected with the black phosphorus material 10, and electrons/ions can still be transmitted to other black phosphorus materials 10 through the stabilizer 20, so that the play of the multiplying power performance of the black phosphorus material is not affected. More importantly, the strong binding force between the stabilizer 20 and the black phosphorus material 10 also makes the effect of the charge and discharge products of the black phosphorus in the composite anode material 100 and the stabilizer 20 stronger (or, the cohesive force of the charge and discharge products of the composite anode material 100) than the acting force between the charge and discharge products and the electrolyte, so that the charge and discharge products are difficult to react by the electrolyte solvent, the stability of the composite anode material 100 is ensured, and the irreversible attenuation of the battery capacity is avoided.

In the present embodiment, the carbon material 30 may encapsulate the black phosphorus material 10 and the stabilizer 20 (see fig. 1a and 1 b). The encapsulation of the carbon material 30 can play a role in preventing the charge and discharge products of the black phosphorus material 10 from being dissolved/reacted by the electrolyte solution therefrom, and can also suppress the volume expansion effect of the black phosphorus material, increasing the stability of the overall composite anode material 100. In addition, the encapsulation of the carbon material 30 also facilitates its formation of a composite conductive network with the stabilizer 20.

In the present embodiment, the thickness of the carbon material layer coating the black phosphorus material 10 and the stabilizer 20 may be 1nm to 1000nm. The thickness of the carbon material layer can be adjusted according to the sizes of the black phosphorus material and the stabilizer, and the proper thickness of the carbon material layer can ensure that the composite anode material 100 builds a carbon-stabilizer composite conductive network with complete structure, and can avoid the influence of excessive thickness on the timely release of active lithium, increase the impedance of a battery and the like. Specifically, the thickness of the carbon material layer may be specifically 10nm, 20nm, 30nm, 40nm, 50nm, 60nm, 80nm, 120nm, 200nm, 500nm, 800nm, 900nm, or the like. In some embodiments, the coating thickness of the carbon material layer is 5nm to 100nm. At this time, the thickness of the carbon material layer can better ensure the structural integrity of the carbon-stabilizer composite conductive network and avoid affecting the timely release of active lithium.

In this application, the structure of the composite anode material 100 may include at least one of those shown in fig. 1a to 1 b. In the present embodiment, the surface of the black phosphorus material 10 is distributed with the stabilizer 20 in contact therewith (see fig. 1a and 1 b). In some embodiments, the stabilizer 20 may be distributed around the black phosphorus material without contacting the black phosphorus material (see fig. 1 a), and the situation shown in fig. 1a may be summarized as that the stabilizer 20 is distributed in the black phosphorus material 10, and the stabilizer 20 may be understood as being distributed in the carbon material layer. At this time, the stabilizer 20 may be scattered and attached to the surface of the black phosphorus material 10, and no coating layer is formed. In other embodiments, referring to fig. 1b, the particle surfaces of the black phosphorus material 10 may also be coated with a stabilizer 20. When the stabilizer 20 coats the black phosphorus material 10, it may coat the entire surface of the black phosphorus material particles as shown in fig. 1b, or may coat only a part of the surface of the black phosphorus material particles, and may be continuous coating or discontinuous coating. Of course, in other embodiments of the present application, the stabilizer may also be doped into a bulk phase (not shown) of the black phosphorus material, and the electron conductivity of the black phosphorus material is improved after the stabilizer is doped therein. It should be noted that, the composite anode material 100 shown in fig. 1a or fig. 1b is a primary particle, and a plurality of primary particles shown in fig. 1a or fig. 1b may also form secondary particles, for example, a plurality of primary particles shown in fig. 1a may form secondary particles as shown in fig. 1 c.

In some embodiments of the present application, the stabilizer 20 forms a stabilizer coating layer of a certain thickness on the particle surfaces of the black phosphorus material 10 (see fig. 1 b). In this case, the stabilizer in contact with the black phosphorus material may be up to 100%, which is more advantageous for bonding the stabilizer 20 with the black phosphorus material 10 and for establishing a good composite conductive network between the stabilizer 20 and the carbon material 30. Wherein the thickness of the stabilizer coating layer may be 1nm to 1000nm. The stabilizer coating layer with proper thickness can effectively inhibit side reaction between the lithium intercalation product of the black phosphorus material and the electrolyte, and meanwhile, the specific capacity of the composite anode material can not be reduced due to the overlarge thickness of the coating layer, and the energy density of the battery is reduced. In some embodiments, the stabilizer coating layer has a thickness of 5nm to 100nm. Specifically, the thickness of the stabilizer coating layer may be specifically 10nm, 20nm, 30nm, 40nm, 50nm, 60nm, 80nm, 90nm, or the like.

In the present embodiment, the stabilizer 20 may include aluminum Al, tin Sn, bismuth Bi, antimony Sb, germanium Ge and alloys thereof (such as SnSb, snGe, etc.), tin selenide SnSe, doped lithium titanate (Li ₄ Ti ₅ O ₁₂ ) Lithium thiophosphate (Li) ₃ PS ₄ ) Aluminum oxide (Al) ₂ O ₃ ) Tin oxides (e.g. SnO) ₂ 、Sn ₂ O ₃ 、Sn ₃ O ₄ ) One or more of transition metal oxides. In the present application, when the expression "plurality" is referred to, the expression "plurality" means two or more. Wherein the transition metal oxide containing doping element includes but is not limited to titanium niobium oxide (TiNb) ₂ O ₇ ) Niobium oxide, vanadium oxide, titanium oxide, iron oxide, manganese oxide, and the like.

Wherein Al, sn, bi, sb, ge, snSb, snGe, snSe and the like can satisfy the above band gap of less than 3eV and lithium ion diffusion coefficient of more than 10 ^-12 cm ² Requirements of/s. The introduction of doping elements in lithium titanate, lithium thiophosphate, aluminum oxide, tin oxide, transition metal oxide, etc. is also required to enable the resulting doping type material to meet the above requirements.

The doping element contained in the lithium titanate may include one or more of lithium Li, titanium Ti, nitrogen N, phosphorus P, carbon C, fluorine F, chlorine Cl, bromine Br, aluminum Al, magnesium Mg, calcium Ca, strontium Sr, barium Ba, silver Ag, copper Cu, tin Sn, nickel Ni, molybdenum Mo, cobalt Co, chromium Cr, zirconium Zr, vanadium V, tantalum Ta, lanthanum La, samarium Sm, and the like. That is, non-metal anions such as nitrogen N, phosphorus P, carbon C, fluorine F, bromine Br and the like can be adopted for doping, metal or transition metal cations can be selected for doping, and anion-cation co-doping can be adopted. Specifically, the doped lithium titanate may be N-doped, ca-doped, ag-doped, sn-doped, mg+f-doped, or cu+br-doped lithium titanate. The doping element can be used according to the above-mentioned "band gap is less than 3eV, lithium ion diffusion coefficient is greater than 10 ^-12 cm ² The requirements of/s' are adjusted.

Among them, the doping element contained In lithium thiophosphate is usually a metal element and/or a transition metal element, such as one or more of aluminum Al, magnesium Mg, calcium Ca, strontium Sr, barium Ba, scandium Sc, gallium Ga, indium In, niobium Nb, tantalum Ta, vanadium V, and the like. Specifically, the doped lithium thiophosphate may be Al-mono-doped, nb-mono-doped, or mg+in co-doped lithium thiophosphate.

The doping element contained in the aluminum oxide, tin oxide, or transition metal oxide includes one or more of a metal element (i.e., a main group metal element), a transition metal element (lanthanoid element is also included in the transition metal element range), and a nonmetal element. The doping element contained in the vanadium oxide is typically a metal element, and may include one or more of iron Fe, silver Ag, copper Cu, chromium Cr, tungsten W, molybdenum Mo, niobium Nb, lanthanum La, cerium Ce, praseodymium Pr, nd neodymium, and the like, for example. In particular, the doped vanadium oxide may be Fe, ag, cu or Nb doped V ₂ O ₅ 、V ₆ O ₁₃ Etc.

Among them, the doping elements contained in the titanium niobium oxide may include, but are not limited to, one or more of chromium Cr, nickel Ni, manganese Mn, zinc Zn, and the like. For example, the doped element-containing titanium niobium oxide may be Cr ³⁺ Doped TiNb ₂ O ₇ . The doping elements contained in the niobium oxide may include, but are not limited to, one or more of lithium Li, gold Au, titanium Ti, iron Fe, zinc Zn, hafnium Hf, cu, gadolinium Gd, erbium Er, yttrium Y, manganese Mn, carbon C, nitrogen N, and boron B. In some embodiments, the doping element contained in the niobium oxide includes one or more of Au, ti, C, N.

The doping element contained In the titanium oxide may include one or more of a metal element, a transition metal element, and a non-metal element, including, for example, but not limited to, one or more of potassium K, aluminum Al, bismuth Bi, tin Sn, indium In, sb, niobium Nb, gold Au, silver Ag, cobalt Co, lanthanum La, vanadium V, iron Fe, copper Cu, nickel Ni, zinc Zn, manganese Mn, germanium Ge, boron B, carbon C, nitrogen N, phosphorus P, sulfur S, selenium Se, and iodine I. In particular, the doped titanium oxide may be N-doped TiO ₂ Nb-doped TiO ₂ 。

In some embodiments of the present application, the stabilizer comprises one or more of aluminum Al, tin Sn, bismuth Bi, antimony Sb, germanium Ge, snSb alloy, snGe alloy, snSe tin selenide, and doped element-containing lithium titanate, lithium thiophosphate, titanium niobium oxide, vanadium oxide, titanium oxide.

In some embodiments of the present application, the particle size of the stabilizer 20 may be 1nm to 1000nm. The stabilizer with proper particle size can ensure enough and effective binding sites with the black phosphorus material, and can ensure the convenience of the preparation of the stabilizer, for example, the synthesis of the stabilizer with too small particle size requires more complicated and harsh experimental conditions. By way of example, the particle size of the stabilizer 20 may be 5nm, 10nm, 20nm, 30nm, 50nm, 70nm, 90nm, 100nm, 300nm, 500nm, 800nm, 900nm, etc. In some embodiments, the particle size of the stabilizer 20 is 1nm to 100nm. The stabilizing agent with the particle size in the range has stronger chemical bonding capability with the black phosphorus material, and is beneficial to improving the structural stability and the cycle stability of the composite anode material.

In the embodiment of the application, the composite anode material 100 comprises the following components in percentage by mass: 50% -90% of black phosphorus material 10,2-48% of carbon material 30 and 2-48% of stabilizer 20. Wherein, the mass ratio of the black phosphorus material 10 is more than or equal to 50 percent, and the high capacity characteristic of the whole composite anode material 100 can be ensured. The appropriate amount of carbon material 30 can ensure good dispersibility of the black phosphorus material 10 and the stabilizer 20, and structural stability of the overall composite anode material 100. The stabilizer 20 in an appropriate amount can ensure sufficient bonding ability with the black phosphorus material 10 and an improvement in ion and electron conductivity of the overall composite anode material 100.

To better ensure that more stabilizer 20 can contact the surface of the black phosphorus material 10, and at the same time ensure that the high capacity characteristics of the overall composite anode material 100 are exhibited, in some embodiments of the present application, the mass of the stabilizer 20 is 4% -53% of the mass of the black phosphorus material 10. Specifically, the mass of the stabilizer 20 may be 8%, 10%, 15%, 20%, 25%, 30%, 35% or the like of the mass of the black phosphorus material 10. In some embodiments of the present application, the mass of the stabilizer 20 is preferably 12% -30% of the mass of the black phosphorus material 10.

Further, the mass of the stabilizer 20 in direct contact with the black phosphorus material 10 may account for 10-100% of the total mass of the stabilizer. At this time, more stabilizers 20 are in direct contact with the black phosphorus material 10 (the proportion of the stabilizers in contact with the black phosphorus material in fig. 1b can reach 100%), and more stabilizers can form chemical bonds with the black phosphorus material 10 correspondingly, so that the close combination of the stabilizers 20 and the black phosphorus material 10 can be better ensured, the problem that the black phosphorus charge and discharge products are reacted by the electrolyte can be better relieved, and the negative problems such as collapse of the conductive network caused by volume expansion of the black phosphorus can be reduced.

In the present embodiment, the black phosphor material 10 is a two-dimensional layered black phosphor, such as a black phosphor nano-sheet, a black phosphor micro-sheet, a black phosphor quantum dot, and the like. From a crystalline or non-crystalline perspective, the black phosphorus material 10 may be black phosphorus crystals and/or amorphous black phosphorus. The carbon material 30 may include, but is not limited to, one or more of artificial graphite, natural graphite, graphene, carbon nanotubes, carbon fibers, soft carbon such as mesophase carbon microspheres, hard carbon such as carbon black, pyrolytic carbon, and activated carbon.

The composite anode material can be prepared by a direct mixing method or an in-situ reaction method. The direct mixing method herein refers to taking a prepared or commercially available black phosphorus material and compounding it with a stabilizer and a carbon material. As will be described in detail below. The in-situ reaction method mainly means that the black phosphorus material is prepared by in-situ reaction after the synthetic raw material is mixed with the stabilizer and the carbon material. Namely, the black phosphorus synthesis raw material is mixed with the stabilizer and the carbon material, and after the reaction, the composite anode material containing the black phosphorus material, the stabilizer and the carbon material is obtained. The in-situ reaction method can be obtained by a gas phase conversion method, a red phosphorus high-energy ball milling method, a liquid phase stripping method (such as an ultrasonic stripping method), a solvothermal method or a gas phase deposition method (such as a plasma sputtering method) and the like.

In some embodiments, the in situ reaction process is an in situ gas phase conversion process. At this time, the preparation method of the composite anode material may specifically include:

mixing red phosphorus, a gas phase transfer catalyst, a stabilizer and a carbon material, sealing (for example, placing in a quartz bottle), heating to 400-1500 ℃ in heating equipment (for example, a tube furnace), slowly cooling to 300-650 ℃, preserving heat for a certain time to convert the red phosphorus into black phosphorus, cooling to room temperature, and collecting to obtain the composite anode material.

Wherein the vapor phase transfer catalyst may include Sn and SnI ₄ They can be subsequently separated from the target product by refluxing with a solvent such as toluene. The time for the heat preservation can be 2-10 h.

In some embodiments, the direct mixing method for preparing the composite anode material may specifically include:

and mixing the black phosphorus material with a stabilizer and a carbon material raw material to obtain the composite anode material.

The carbon material raw material can be directly selected from the required carbon materials, can also be selected from carbon sources required for synthesizing the carbon materials, and can be solid or gas. The mixing mode can be one or more of a mechanical stirring method, a high-energy ball milling method, a mechanical fusion method, a coating method, a vapor deposition method, a solid phase sintering method, a thermal decomposition method and the like. The coating mode can specifically comprise one or a combination of a plurality of modes of dripping, brushing, spraying, dipping, scraping and spin coating. The vapor deposition method includes physical vapor deposition (such as vapor deposition, magnetron sputtering, vacuum thermal deposition, etc.), chemical vapor deposition, atomic layer deposition, etc. Wherein, when adopting a mechanical stirring method, a high-energy ball milling method, a mechanical fusion method, a solid phase sintering method and the like, the required carbon materials can be directly selected for mixing. When preparing the carbon material by chemical vapor deposition or thermal decomposition, the raw material to be selected for forming the carbon material may be an organic carbon source. When the coating method is adopted, the coating liquid can contain carbon materials, can also contain organic carbon sources required by synthesizing the carbon materials, and can be subsequently converted into the carbon materials through high-temperature sintering.

In some embodiments, the above mixing is by one or more of mechanical stirring, high energy ball milling, mechanical fusion, preferably high energy ball milling or mechanical fusion. These mixing modes can be carried out in the presence or absence of a solvent. In some embodiments, the mixing is performed by a high energy ball milling process, wherein the rotational speed of the high energy ball milling process may be 300r/min to 1200r/min and the milling time may be 2h to 48h. In a specific embodiment, the rotation speed of the high-energy ball milling can be 400-700r/min, and the ball milling time can be 5-24 h, and further can be 10-24 h.

In some embodiments, the mixing may be by mixing the black phosphorus material and the stabilizer (e.g., high energy ball milling) and then mixing the resulting mixture with the carbon material feedstock. The step-by-step mixing is more beneficial to obtaining the composite anode material with the three-layer core-shell structure shown in the figure 1 b. At this time, the preparation method of the composite anode material may specifically include:

s01, taking a black phosphorus material, and mixing the black phosphorus material with a stabilizer to obtain a core material;

s02, constructing a carbon material layer for wrapping the core material, and obtaining the composite anode material.

In step S01, the mixing method may be one or more of a mechanical stirring method, a high-energy ball milling method, a mechanical fusion method, and the like. In step S02, the method of constructing the carbon material layer may include at least one of a ball milling method, a mechanical fusion method, a coating method, a vapor deposition method, a solid phase sintering method, and a thermal decomposition method. Specific coating methods, vapor deposition methods, and the like may be as described herein before, and the manner of constructing the carbon material layer may be selected according to the specific carbon material raw material. In some embodiments, the mixing manner in step S01 and the method for constructing the carbon material layer in step S02 are ball milling. At the moment, the preparation process of the composite anode material is simple, easy to operate and suitable for mass production.

The embodiment of the application also provides a negative electrode plate for a battery, which comprises the composite negative electrode material 100. In one embodiment, the negative electrode tab includes a negative electrode current collector and a negative electrode material layer disposed on the negative electrode current collector, where the negative electrode material layer includes a negative electrode active material and a binder, and the negative electrode active material includes the composite negative electrode material 100 described above in the embodiments of the present application. In some embodiments, the mass ratio of the composite anode material 100 in the anode material layer may be greater than or equal to 70wt%, for example, 80% -90%. The higher mass fraction composite anode material 100 can result in a higher specific capacity of the anode tab. In some embodiments, a conductive agent may be further included in the anode material layer.

The negative electrode current collector includes, but is not limited to, a metal foil or alloy foil, the surface of which may be etched or roughened to form a secondary structure that facilitates effective contact with the negative electrode material layer. Exemplary metal foil may be copper foil or carbon coated copper foil, and exemplary alloy foil may be stainless steel foil, carbon coated stainless steel foil or copper alloy foil. The binder may specifically include, but is not limited to, one or more of Polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), sodium carboxymethyl cellulose (CMC), polyacrylic acid (PAA), polyacrylate, polyacrylamide (PAM), polyimide (PI), and the like. The conductive agent may specifically include, but is not limited to, one or more of acetylene black, ketjen black, provider P conductive carbon black, graphite, graphene, carbon nanotubes, carbon fibers, and the like.

In some embodiments, the anode active material may also include other anode active components including, but not limited to, one or more of lithium titanate, carbon-based materials, silicon-based materials, tin-based materials, germanium-based materials, antimony-based materials, bismuth-based materials. Wherein, the carbon-based material can comprise graphite (such as natural graphite, artificial graphite), non-graphitized carbon (soft carbon, hard carbon, etc.); the silicon-based material may include one or more of elemental silicon, silicon-based alloys, silicon oxides, silicon-carbon composites, and the like; the tin-based material may include one or more of elemental tin, tin alloys, tin oxides, and the like; the germanium-based material may include one or more of elemental germanium, germanium alloys, germanium carbon composites, germanium oxides, and the like; the antimony-based material comprises one or more of an antimony simple substance, an antimony alloy and the like; the bismuth-based material includes one or more of bismuth simple substance, bismuth alloy, etc.

Other negative active components may be dispersed in the negative material layer together with the above-mentioned composite negative material 100, and may exist independently, or may exist in a composite form, where the two composite forms may be in a form that particles of two types of material particles contact, for example, the surface of the composite negative material 100 is distributed with other negative active components 101 (as shown in fig. 2), or the two forms a coating relationship. The composite material may be constructed by, but not limited to, ball milling, stirring, mechanical fusion, solid phase sintering, vapor deposition, solvothermal, etc. as described herein before. In some embodiments, the method of forming the composite material includes stirring and high temperature solid phase sintering in sequence. For example, the stirring rate may be 10 to 2000 rpm, the stirring time may be 0.1 to 12 hours, and the high temperature solid phase sintering temperature may be 100 to 800 ℃, for example 300 to 700 ℃.

The preparation method of the negative electrode plate can comprise the following steps: mixing a negative electrode active material, a binder and an optional conductive agent with a solvent to prepare a negative electrode slurry; and coating the negative electrode slurry on a negative electrode current collector, drying and rolling to obtain a negative electrode plate. The solvent in the negative electrode slurry may be one or more of water, an alcoholic solvent (such as ethanol, etc.), N-methylpyrrolidone (NMP), dimethylformamide (DMF), etc. The mixing can be achieved by mechanical stirring at a speed of 10-3000 rpm, and the stirring time can be 0.5-10 h. The drying may be performed at a temperature of 45-120 ℃. The specific mixing process parameters and drying process can be adjusted according to the cathode slurry. In addition, if the negative electrode material layer contains the composite negative electrode material 100 and other negative electrode active components, the two may be mixed with the binder and the conductive agent at the same time, or may be mixed to form a composite material, and then mixed with the binder and the conductive agent.

Referring to fig. 3, an embodiment of the present application further provides a secondary battery 200 including the above-described negative electrode tab. The secondary battery 200 may be specifically a lithium secondary battery including a positive electrode 201, a negative electrode 202, an electrolyte 203 provided between the positive electrode 201 and the negative electrode 202, a separator 204, and corresponding communication auxiliaries and circuits. The negative electrode 202 includes the negative electrode tab described in the embodiments of the present application. Positive electrode 201 may include a positive electrode current collector including, but not limited to, a metal foil or alloy foil, such as aluminum foil, and a positive electrode material layer disposed on the positive electrode current collector. The positive electrode material layer includes a positive electrode active material including, but not limited to, one or more of lithium iron phosphate, lithium manganese iron phosphate, lithium vanadium phosphate, lithium cobalt oxide, lithium manganate, lithium nickel manganate, nickel Cobalt Manganese (NCM), nickel Cobalt Aluminum (NCA), and the like. The electrolyte includes a lithium salt and an organic solvent, which may include, but is not limited to, one or more of carbonate solvents, carboxylate solvents, ether solvents. The separator may be a polymer separator, a nonwoven fabric, etc., including but not limited to, a single layer PP (polypropylene) film, a single layer PE (polyethylene) film, a double layer PP/PE, a double layer PP/PP, and a triple layer PP/PE/PP, etc.

When the lithium secondary battery is charged, lithium ions are separated from the positive electrode 201 and migrate to the negative electrode 202 through the internal electrolyte, meanwhile, electrons flow from the positive electrode to the negative electrode through the external circuit, the open-circuit voltage of the battery is increased, and electric energy is stored; during discharge, lithium ions are separated from the negative electrode 202 and returned to the positive electrode 201 through the electrolyte, corresponding electrons migrate from the negative electrode to the positive electrode from the external circuit, the voltage is reduced, and electric energy is released. When the positive electrodes of the batteries are the same, the capacity and the multiplying power of the negative electrodes are important to the improvement of the energy density and the quick charge performance of the whole battery core. The negative electrode of the lithium secondary battery contains the composite negative electrode material 100, wherein the high specific capacity characteristic of the black phosphorus can be fully exerted, and the carbon material and the stabilizer in the composite negative electrode material can effectively solve the negative problems of collapse of a conductive network and the like caused by volume expansion of the black phosphorus in the charging and discharging process, and the problem that the charging and discharging products of the black phosphorus are easy to react by an electrolyte is controlled, so that the lithium secondary battery also has better cycle stability and rate capability.

The shape of the lithium secondary battery according to the embodiment of the present application is not particularly limited, and may be a cylinder type, a button type (coin type), a flat type, a square type, or the like. The lithium secondary battery provided by the embodiment of the application can be used for terminal consumer products such as mobile phones, tablet computers, mobile power supplies, portable computers, notebook computers, digital cameras, other wearable or movable electronic equipment, unmanned aerial vehicles, automobiles and other products, so that the product performance is improved.

The embodiment of the application also provides electronic equipment with the secondary battery. The electronic device may be any consumer electronic product including a mobile phone, tablet, portable power source, portable device, notebook, and other wearable or removable electronic device, television, video disc player, video recorder, camcorder, radio recorder, audio set, record carrier, compact disc player, laser player, home office equipment, home electronic health care equipment, and may also be any electronic product such as an automobile, energy storage device, etc.

In some embodiments, referring to fig. 4, an electronic device 300 is provided in the present embodiment, which includes a housing 301, and electronic components (not shown in the drawings) and a battery 302 that are accommodated in the housing 301, where the battery 302 supplies power to the electronic device 300, and the battery 302 includes the lithium secondary battery described in the present embodiment. In some embodiments, the housing 301 may include a front cover assembled at the front side of the terminal and a rear case assembled at the rear side, and the battery 302 may be fixed inside the rear case. The electronic device 300 shown in fig. 4 is typically a small portable electronic device, such as a cell phone.

In other embodiments, referring to fig. 5, an example of an electronic device 400 is provided, which may be various mobile devices for loading, transporting, assembling, disassembling, security, etc., and may be various forms of vehicles. Specifically, the electronic device 400 may include a vehicle body 401, a moving assembly 402, and a driving assembly including a motor 403 and a battery system 404, the battery system 404 including the above-described secondary battery 200 provided in the embodiments of the present application. Wherein the moving assembly 402 may be a wheel; the secondary battery 200 may be accommodated in a battery pack (i.e., the battery system 404 is a battery pack) at the bottom of the vehicle body, and the battery system 404 is electrically connected to the motor 403, which may supply power to the motor 403, and the motor 403 provides power to drive the moving component 402 of the electronic device 400 to move.

The negative electrode active material of the battery in the electronic equipment comprises the composite negative electrode material, so that the cycle performance, the multiplying power performance, the energy density, the power performance and the like of the battery are improved, the requirements of the electronic equipment on long cycle life, high energy density and the like of the battery can be better met, and the use experience and the market competitiveness of the electronic equipment are improved.

The embodiments of the present application are further described below in terms of a number of examples.

Example 1

A preparation method of the composite anode material comprises the following steps:

in an argon-filled environment, according to black phosphorus: stabilizers (specifically nitrogen doped lithium titanate): and (3) weighing the raw materials according to the mass ratio of graphite=7:1:2, putting the raw materials into a ball milling tank, mixing the raw materials uniformly, and performing high-energy ball milling for 10-12 hours at the rotating speed of 400 rpm to obtain the black phosphorus-nitrogen doped lithium titanate-graphite composite anode material. In the composite anode material, at least part of stabilizer is distributed on the surface of the black phosphorus material, wherein the band gap of nitrogen doped lithium titanate is less than 3eV, and the number level of the lithium ion diffusion coefficient reaches 10 ^-11 cm ² /s。

Preparation of lithium secondary battery

Mixing the composite anode material serving as an anode active material with Super P carbon black conductive agent and binder CMC in a solvent NMP according to a mass ratio of 8:1:1, and uniformly stirring to obtain anode slurry; coating the negative electrode slurry on copper foil, vacuum drying for 12h at 110 ℃, rolling to obtain a negative electrode plate, taking a metal lithium plate as a counter electrode, and using a commercial PE diaphragm and 1mol/L LiPF ₆ And (2) electrolyte (EC+DEC) (volume ratio 1:1), and assembling the electrolyte into the 2032 type button cell in a glove box protected by argon.

Example 2

A preparation method of the composite anode material comprises the following steps: 500mg of red phosphorus, a vapor phase transfer catalyst (specifically 20mg of Sn and 10mg of SnI) are added into a quartz tube ₄ ) The preparation method comprises the steps of mixing and grinding germanium powder and porous carbon powder in advance, adding the mixture into a tubular furnace after vacuumizing and sealing, heating to 950 ℃ firstly, then slowly cooling in 5 h) to 550 ℃ and preserving heat for 2h, cooling to room temperature, and taking out a sample to obtain the black phosphorus-germanium-carbon composite anode material.

The composite anode material and a graphite anode material (the graphite content is 10 wt%) are placed in a fusion machine, and are stirred and mixed for 2 hours at a high speed at a temperature of 120 ℃ under 1000r/min to obtain a (black phosphorus-germanium-carbon) -graphite composite material which is used as an anode active material.

The composite negative electrode material was used as a negative electrode active material, and a 2032 type coin cell was assembled in the same manner as in example 1.

Example 3

A preparation method of the composite anode material comprises the following steps: in an argon-filled environment, according to black phosphorus: stabilizer (specifically tin powder): weighing all raw materials according to the mass ratio of Super P carbon black=55:15:30, putting the raw materials into a ball milling tank, uniformly mixing, and performing high-energy ball milling for 8 hours at the rotating speed of 300 rpm to obtain the black phosphorus-tin-carbon composite anode material. In the composite anode material, at least part of the stabilizer is distributed on the surface of the black phosphorus material.

Example 4

A preparation method of the composite anode material comprises the following steps: 500mg of red phosphorus, a vapor phase transfer catalyst (specifically 20mg of Sn and 10mg of SnI) are added into a quartz tube ₄ ) The preparation method comprises the steps of (1) mixing a stabilizer (specifically 20mg of selenium tin) and 100mg of ketjen black (wherein the selenium tin and the ketjen black can be mixed and ground in advance and then added), vacuumizing and sealing, placing into a tube furnace, heating to 1100 ℃, then slowly cooling in 5 hours) to 500 ℃, preserving heat for 1 hour, cooling to room temperature, and taking out a sample to obtain the black phosphorus-selenium tin-carbon composite anode material.

Example 5

A preparation method of the composite anode material comprises the following steps: in an argon-filled environment, according to black phosphorus: stabilizers (specifically tin doped lithium thiophosphate): weighing all raw materials according to the mass ratio of Super P carbon black=65:5:30, putting the raw materials into a ball milling tank, mixing the raw materials uniformly, and performing high-energy ball milling for 8 hours at the rotating speed of 400 rpm to obtain the black phosphorus-tin doped lithium thiophosphate-carbon composite anode material. In the composite anode material, at least part of the stabilizer is distributed on the surface of the black phosphorus material.

Example 6

A preparation method of the composite anode material comprises the following steps: in an argon-filled environment, according to black phosphorus: stabilizer (specifically niobium doped vanadium oxide): weighing all raw materials according to the mass ratio of Super P carbon black=70:5:25, putting the raw materials into a ball milling tank, mixing the raw materials uniformly, and performing high-energy ball milling for 6 hours at the rotating speed of 500 revolutions per minute to obtain the black phosphorus-niobium doped vanadium oxide-carbon composite anode material. In the composite anode material, at least part of the stabilizer is distributed on the surface of the black phosphorus material.

To highlight the beneficial effects of the examples of the present application, the following comparative example 1 is specifically provided.

Comparative example 1

A phosphorus-carbon composite material is obtained by performing high-energy ball milling on black phosphorus and graphite in a mass ratio of 7:3, and a specific ball milling process is the same as that in example 1 of the application.

The phosphorus-carbon composite material provided in comparative example 1 was used as a negative electrode active material, and a 2032 type coin cell was assembled in the same manner as in example 1.

In order to strongly support the beneficial effects of the embodiment of the application, the following battery performance tests are provided: each button cell was subjected to a charge-discharge capacity test and a first coulombic efficiency test according to a charge-discharge regime of 0.05C/0.05C, a voltage range of 0.1V-2V, a rate charge test according to 1C/0.2C, and a cycle performance test according to 0.2C/0.2C, and the test results are shown in Table 1 below.

The average coulombic efficiency is a value obtained by dividing the sum of the coulombic efficiencies of each turn by the total number of turns in the cycle test. The 1C/0.2C rate refers to the ratio of the discharge capacity of the button cell measured at a current density of 1C to the discharge capacity obtained at a current density of 0.2C, and the ratio can measure the rate performance of the cell.

TABLE 1 electrochemical performance results

As can be seen from table 1, the first discharge specific capacity, the first coulombic efficiency, the average coulombic efficiency, the capacity retention rate after 100 weeks of cycle and the rate capability of the button cell prepared by using the composite anode material provided in the embodiment of the present application are all better, and under the same conditions, the above performances of the battery in the embodiment 1 of the present application are all significantly higher than those of the battery in the comparative example 1.

Claims

1. A composite anode material is characterized by comprising a black phosphorus material, a stabilizer and a carbon material, wherein at least part of the stabilizer is distributed on the surface of the black phosphorus material, the stabilizer is a material capable of forming a chemical bond with bond energy larger than P-C bond energy with the black phosphorus material, the band gap of the stabilizer is smaller than 3eV, and the lithium ion diffusion coefficient is larger than 10 ^-12 cm ² /s。

2. The composite anode material of claim 1, wherein the stabilizer comprises one or more of aluminum, tin, bismuth, antimony, germanium, alloys thereof, tin selenide, and doped lithium titanate, lithium thiophosphate, aluminum oxide, tin oxide, transition metal oxide.

3. The composite anode material according to claim 2, wherein the doping element contained in the lithium titanate includes one or more of Li, ti, N, P, C, F, cl, br, al, mg, ca, sr, ba, ag, cu, sn, ni, mo, co, cr, zr, V, ta, la, sm;

the doping elements contained in the lithium thiophosphate comprise one or more of Al, mg, ca, sr, ba, sc, ga, in, nb, ta and V;

the doping elements contained in the aluminum oxide, the tin oxide and the transition metal oxide comprise one or more of metal elements, transition metal elements and nonmetal elements.

4. The composite anode material according to any one of claims 1 to 3, wherein the black phosphorus material accounts for 50 to 90% by mass of the composite anode material.

5. The composite anode material according to any one of claims 1 to 4, wherein the carbon material is present in the composite anode material in an amount of 2 to 48% by mass.

6. The composite anode material according to any one of claims 1 to 5, wherein the mass ratio of the stabilizer in the composite anode material is 2% to 48%.

7. The composite anode material according to any one of claims 1 to 6, wherein the mass of the stabilizer is 4% to 53% of the mass of the black phosphorus material.

8. The composite anode material according to any one of claims 1 to 7, wherein the mass of the stabilizer in direct contact with the black phosphorus material is 10% to 100% of the total mass of the stabilizer.

9. The composite anode material according to any one of claims 1 to 8, wherein the carbon material encapsulates the black phosphorus material and the stabilizer.

10. The composite anode material of claim 9, wherein the carbon material layer surrounding the black phosphorus material and the stabilizer has a thickness of 1nm to 1000nm.

11. The composite anode material according to claim 9, wherein a stabilizer is distributed in the black phosphorus material, and/or the surface of the black phosphorus material particles is coated with the stabilizer.

12. The composite anode material according to claim 11, wherein the stabilizer forms a stabilizer coating layer having a thickness of 1nm to 1000nm on the surface of the black phosphorus material particles.

13. The composite anode material of any one of claims 1-12, wherein the carbon material comprises one or more of artificial graphite, natural graphite, graphene, carbon nanotubes, carbon fibers, mesophase carbon microspheres, carbon black, pyrolytic carbon, activated carbon.

14. A negative electrode tab comprising a negative electrode current collector and a negative electrode material layer disposed on the negative electrode current collector, the negative electrode material layer comprising the composite negative electrode material of any one of claims 1-13 and a binder.

15. The composite anode material of claim 14, wherein the anode material layer further comprises other anode active components comprising one or more of lithium titanate, carbon-based materials, silicon-based materials, tin-based materials, germanium-based materials, antimony-based materials, bismuth-based materials.

16. A secondary battery comprising the negative electrode tab of claim 14 or 15.

17. An electronic device comprising the secondary battery according to claim 16.