Preparation method of negative plate, battery and vehicle

Abstract

The invention discloses a preparation method of a negative plate, a battery and a vehicle, and relates to the technical field of batteries, lithium metal, a lithium-loving nano material and a carbon material are mixed to form a mixture, and the mixture is heated to a preset temperature for alloying; meanwhile, stirring the mixture in the heating process, obtaining a reacted material after the reaction is completed, and tabletting and cutting the reacted material to obtain the negative electrode plate. The negative electrode plate with a three-dimensional space structure is constructed through the lithium metal, the lithium-loving nanometer material and the carbon material, the problem of volume expansion in the lithium ion deintercalation process can be inhibited, the carbon material is fully connected with the alloy in the reaction process, so that the interior of the negative electrode material structure has better electronic conductivity, and the lithium ion battery performance is improved. And the lithium ion diffusion kinetics in the pole piece can be improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of batteries, and in particular to a preparation method of a negative electrode sheet, a battery and a vehicle. BACKGROUND

[0002] Lithium metal or lithium alloy is usually used as a negative electrode material in a lithium ion battery. During charging, lithium ions and electrons are released from the positive electrode, lithium ions are embedded in the negative electrode to form neutral lithium atoms, and are stored there. During discharging, lithium ions and electrons are released from the negative electrode and move back to the positive electrode to provide power to external devices.

[0003] In some related technologies, in a liquid lithium battery, due to uneven current distribution at the electrolyte or lithium metal interface, lithium metal is unevenly deposited and peeled off, lithium dendrites are easily formed at the interface, leading to internal short circuit of the battery; and for a lithium battery using a solid electrolyte, for example, a sulfide solid electrolyte is used in the lithium battery, when the lithium metal matches the sulfide solid electrolyte, there are problems such as lithium dendrite growth and interface side reaction, leading to volume expansion problem of the battery in the cycle process, and poor long cycle stability of the battery. SUMMARY

[0004] To solve at least one problem mentioned in the background, the present application provides a preparation method of a negative electrode sheet, a battery and a vehicle. The lithium source can be ensured to be sufficient in the cycle process by using the negative electrode sheet, and the loss of irreversible lithium is supplemented, and the negative electrode sheet is stable to the electrolyte. By introducing a certain proportion of carbon fibers, a continuous electron conduction path can be formed in the structure, which is beneficial to improve the lithium ion diffusion dynamics in the electrode sheet. The stable three-dimensional structure formed by the combination of the negative electrode sheet and the carbon material can effectively alleviate the volume expansion problem of the battery in the cycle process, and ensure the long cycle stability of the battery.

[0005] The specific technical solutions provided by the embodiments of the present application are as follows:

[0006] In a first aspect, a preparation method of a negative electrode sheet is provided, and the method comprises:

[0007] Mixing lithium metal, lithiumophilic nanomaterial and carbon material to form a mixture, and heating the mixture to a preset temperature for alloying;

[0008] Stirring the mixture during the heating process, and obtaining a reacted material after the reaction is completed.

[0009] Tableting and cutting the reacted material.

[0010] In a specific embodiment, the mass percentage of the carbon material in the mixture is 3wt%-5wt%.

[0011] In one specific embodiment, the particle size of the lithiophilic nanomaterial is 10 nm to 100 nm.

[0012] In one specific embodiment, the lithiophilic nanomaterial includes one or more of tin, aluminum, silicon, and silver;

[0013] And / or, the carbon material includes one or more of vapor-grown carbon fibers, SP conductive carbon black, or Ketjen black.

[0014] In one specific embodiment, the amounts of lithium metal and the lithiophilic nanomaterial satisfy the following condition:

[0015] When the lithiophilic nanomaterial includes tin, the lithium metal and the tin are alloyed in an atomic ratio of (22:5) to (22:7) of lithium atoms to tin atoms;

[0016] And / or, when the lithium-loving nanomaterial includes aluminum, the lithium metal and the aluminum foil including the aluminum are alloyed in an atomic ratio of lithium atoms to aluminum atoms of (9:4) to (9:6);

[0017] And / or, when the lithium-loving nanomaterial includes silver, the lithium metal and the silver are alloyed in an atomic ratio of lithium atoms to silver atoms of (1:1) to (1:2);

[0018] And / or, when the lithium-loving nanomaterial includes silicon, the lithium metal and the silicon are alloyed in an atomic ratio of lithium atoms to silicon atoms of (1:1) to (1:2).

[0019] In one specific embodiment, the preset temperature satisfies the following condition:

[0020] When the lithiophilic nanomaterial is tin, the preset temperature is set to 300℃~800℃;

[0021] And / or, when the lithiophilic nanomaterial is aluminum and / or silver, the preset temperature is set to 200℃~700℃;

[0022] And / or, when the lithium-loving nanomaterial is silicon, the preset temperature is set to 300℃~600℃.

[0023] In one specific embodiment, the mixture is mechanically stirred during the heating process, the stirring speed is 500 rpm to 1000 rpm, and the stirring time is 0.5 h to 2 h.

[0024] In one specific embodiment, the thickness of the reacted material after tableting is 90µm to 110µm, the tableting pressure is 2T to 4T, and the tableting holding time is 1min to 2min.

[0025] Secondly, a battery is provided, the battery including a negative electrode sheet, the negative electrode sheet being prepared using the above-described method for preparing a negative electrode sheet.

[0026] Thirdly, a vehicle is provided, the vehicle including the aforementioned battery.

[0027] The embodiments of this application have the following beneficial effects:

[0028] 1. The solution provided in this application combines lithium metal, lithium-loving nanomaterials, and carbon materials to construct a three-dimensional negative electrode sheet. When the negative electrode material is matched with the sulfide solid electrolyte, the interface is stable and the volume expansion problem during the lithium-ion drag-in process can be suppressed. The alloying process adopts a heating and melting reaction method, and stirring is carried out at the same time to make the alloying reaction proceed uniformly, increase the contact area between the various materials, improve the reaction rate, and enable the various materials to react fully, thus ensuring the long-term cycle stability of the battery made from the negative electrode sheet.

[0029] 2. In the three-dimensional spatial structure of the negative electrode sheet constructed in this application, the carbon material used includes a vapor-grown carbon fiber structure. The carbon fiber is in the shape of a strip and can be connected with the alloy during the reaction process, thereby ensuring better electronic conductivity inside the structure, which is beneficial to improving the lithium ion diffusion kinetics in the electrode sheet. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 A schematic diagram illustrating the preparation method of the negative electrode sheet according to this application is shown;

[0032] Figure 2 A schematic diagram of the process for preparing a battery using a negative electrode sheet according to this application is shown. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0034] The "range" disclosed herein is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of the particular range. Ranges defined in this way can include or exclude endpoints and can be combined arbitrarily; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is expected that ranges of 60-110 and 80-120 are also expected. Furthermore, if minimum range values ​​1 and 2 are listed, and if maximum range values ​​3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this disclosure, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0035] Unless otherwise specified, all embodiments and preferred embodiments mentioned herein can be combined to form new technical solutions.

[0036] Unless otherwise specified in this disclosure, all technical features and preferred features mentioned herein can be combined to form new technical solutions.

[0037] In this disclosure, unless otherwise specified, all steps mentioned herein may be performed sequentially or randomly, but are preferably performed sequentially. For example, if the method includes steps (a) and (b), it means that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, if the method may also include step (c), it means that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0038] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the specification of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0039] Example 1

[0040] A method for preparing a negative electrode, such as Figure 1 As shown, the method includes the following steps:

[0041] Step 101: Mix lithium metal, lithium-loving nanomaterials and carbon materials to form a mixture, and heat the mixture to a preset temperature for alloying.

[0042] Lithium metal, lithium-affinity nanomaterials, and carbon materials are added to a crucible in predetermined amounts and mixed to form a mixture. The crucible is placed on a workbench and heated under an inert protective atmosphere, specifically argon or nitrogen. After heating to a predetermined temperature and holding at that temperature for a predetermined time, the components are alloyed.

[0043] Among them, the lithiophilic nanomaterials include one or more of tin, aluminum, silicon, and silver, and the amounts of lithium metal and lithiophilic nanomaterials used meet the following conditions:

[0044] (1) When the lithiophilic nanomaterial includes tin, lithium metal and tin are alloyed according to the atomic ratio of lithium atoms to tin atoms of (22:5) to (22:7);

[0045] Specifically, the atomic ratio of lithium atoms to tin atoms is configured as 22:5, 22:5.5, 22:6, 22:6.5, 22:7, or any range of two of the above values. With the above settings, when lithium metal and tin are added to the crucible in the corresponding amounts according to the above different atomic ratios, an alloying reaction can be achieved.

[0046] (2) Alternatively, when the lithium-loving nanomaterial includes aluminum, lithium metal and aluminum foil containing aluminum are alloyed in an atomic ratio of lithium atoms to aluminum atoms of (9:4) to (9:6);

[0047] Specifically, when the lithium-loving nanomaterial includes aluminum, the aluminum nanoparticles have a large specific surface area and a high content of aluminum oxide on the surface, making it difficult for the aluminum nanoparticles to react with lithium metal. In this case, aluminum foil is required. Specifically, the atomic ratio of lithium metal to aluminum foil is configured to be 9:4, 9:4.5, 9:5, 9:5.5, 9:6, or any combination of two of the above values. With the above settings, when lithium metal and aluminum foil are added to the crucible in the corresponding amounts according to the above different atomic ratios, an alloying reaction can be achieved.

[0048] (3) Alternatively, when the lithium-loving nanomaterial includes silver, lithium metal and silver are alloyed in an atomic ratio of (1:1) to (1:2) between lithium atoms and silver atoms.

[0049] Specifically, when the lithiophilic nanomaterial includes silver, the atomic ratio of lithium atoms to silver atoms is configured as 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4, 1:1.5, 1:1.6, 1:1.7, 1:1.8, 1:1.9, 1:2, or any range of two of the above values. With the above settings, when lithium metal and silver are added to the crucible in the corresponding amounts according to the above different atomic ratios, an alloying reaction can be achieved.

[0050] (4) Alternatively, when the lithium-loving nanomaterial includes silicon, lithium metal and silicon are alloyed in an atomic ratio of (1:1) to (1:2) between lithium atoms and silicon atoms.

[0051] Specifically, when the lithium-loving nanomaterial includes silicon, the atomic ratio of lithium atoms to silicon atoms is configured as 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4, 1:1.5, 1:1.6, 1:1.7, 1:1.8, 1:1.9, 1:2, or any range of two of the above values. With the above settings, when lithium metal and silicon are added to the crucible in the corresponding amounts according to the above different atomic ratios, an alloying reaction can be achieved.

[0052] (5) Alternatively, when the lithiophilic nanomaterial includes one of tin and aluminum, tin and silver, tin and silicon, aluminum and silver, aluminum and silicon, silver and silicon, tin, aluminum and silver, tin, aluminum and silicon, aluminum, silver and silicon, or a combination of tin, aluminum, silver and silicon, the specific raw materials associated with each element, tin, aluminum foil, silver and silicon, are respectively configured according to the corresponding atomic ratio. Through the above settings, when the lithiophilic nanomaterial includes one or more of tin, aluminum, silver and silicon, the alloying reaction is achieved by configuring the amount of lithium metal and each raw material.

[0053] In this embodiment, the particle size of the lithiophilic nanomaterial is configured to be 10 nm to 100 nm.

[0054] Specifically, the particle size configuration of the lithiophilic nanomaterials is 10nm, 20nm, 30nm, 40nm, 50nm, 60nm, 70nm, 80nm, 90nm, 100nm, or any combination of two of the above values. Through this configuration, alloying reactions can be achieved when the lithiophilic nanomaterials are configured with different particle sizes, allowing the lithiophilic nanomaterials to melt with lithium metal and carbon materials to form an alloy phase and a stable three-dimensional structure.

[0055] In one specific embodiment, the carbon material accounts for 3 wt% to 5 wt% of the mixture by mass.

[0056] Specifically, the mass percentage of carbon material in the mixture can be set to 3 wt%, 3.1 wt%, 3.2 wt%, 3.3 wt%, 3.4 wt%, 3.5 wt%, 3.6 wt%, 3.7 wt%, 3.8 wt%, 3.9 wt%, 4 wt%, 4.1 wt%, 4.2 wt%, 4.3 wt%, 4.4 wt%, 4.5 wt%, 4.6 wt%, 4.7 wt%, 4.8 wt%, 4.9 wt%, 5 wt%, or a range of any two of the above values. By setting it as described above, alloying reactions can be achieved regardless of the mass percentage of carbon material in the mixture.

[0057] Furthermore, the carbon material includes one or more of vapor-grown carbon fibers, SP conductive carbon black, and Ketjen black. Moreover, when the carbon material is configured as vapor-grown carbon fibers, these fibers are elongated and can be fully bonded to the alloy during the reaction process, thereby ensuring better electronic conductivity within the structure and improving lithium-ion diffusion kinetics in the electrode.

[0058] In this embodiment, the temperature during the alloying process depends specifically on the composition of the lithium metal and the lithiophilic nanomaterials. Specifically, the preset temperature satisfies the following conditions:

[0059] (1) When the lithiophilic nanomaterial includes tin, the preset temperature is set to 300℃~800℃; specifically, when the lithiophilic nanomaterial includes tin, the preset temperature during the heating process is set to 300℃, 320℃, 340℃, 350℃, 360℃, 380℃, 400℃, 420℃, 440℃, 450℃, 460℃, 480℃, 500℃, 520℃, 540℃, 550℃, 560℃, 580℃, 600℃, 620℃, 640℃, 650℃, 660℃, 680℃, 700℃, 720℃, 740℃, 750℃, 760℃, 780℃, 800℃ or a range of any two of the above values, in conjunction with the melting temperature of tin.

[0060] (2) Alternatively, when the lithiophilic nanomaterial includes aluminum and / or silver, the preset temperature is set to 200℃~700℃. Specifically, when the lithiophilic nanomaterial includes aluminum and / or silver, the preset temperature during the heating process is set to 200℃, 220℃, 240℃, 250℃, 260℃, 280℃, 300℃, 320℃, 340℃, 350℃, 360℃, 380℃, 400℃, 420℃, 440℃, 450℃, 460℃, 480℃, 500℃, 520℃, 540℃, 550℃, 560℃, 580℃, 600℃, 620℃, 640℃, 650℃, 660℃, 680℃, 700℃, or a range consisting of any two of the above values, in conjunction with the melting temperatures of the aluminum foil and silver.

[0061] (3) Alternatively, when the lithiophilic nanomaterial includes silicon, the preset temperature is set to 300℃~600℃; specifically, when the lithiophilic nanomaterial includes silicon, the preset temperature during the heating process is set to 300℃, 320℃, 340℃, 350℃, 360℃, 380℃, 400℃, 420℃, 440℃, 450℃, 460℃, 480℃, 500℃, 520℃, 540℃, 550℃, 560℃, 580℃, 600℃ or a range of any two of the above values, in conjunction with the melting temperature of silicon.

[0062] (4) Alternatively, when the lithiophilic nanomaterial includes one of the following: tin and aluminum, tin and silver, tin and silicon, aluminum and silver, aluminum and silicon, silver and silicon, tin, aluminum and silver, tin, aluminum and silicon, aluminum, silver and silicon, or a combination of tin, aluminum, silver and silicon, the preset temperature is set to a value that simultaneously satisfies the temperature range corresponding to each atom. For example, when the lithiophilic nanomaterial includes tin and aluminum, the preset temperature is set to 300℃~700℃; when the lithiophilic nanomaterial includes tin, aluminum and silicon, the preset temperature is set to 300℃~600℃.

[0063] It should be noted that after heating to the corresponding preset temperature, a preset holding time is set to ensure that the substances react fully. The preset holding time is set to 0.5h to 2h; specifically, the preset holding time is set to 0.5h, 0.6h, 0.7h, 0.8h, 0.9h, 1h, 1.1h, 1.2h, 1.3h, 1.4h, 1.5h, 1.6h, 1.7h, 1.8h, 1.9h, 2h, or any range of two of the above values.

[0064] The above settings ensure that when the lithiophilic nanomaterials undergo an alloying reaction, the temperature during the heating process is first controlled to the melting point of lithium metal, i.e., above 220°C. Then, the final preset temperature is determined based on the specific configuration of the lithiophilic nanomaterials. The melting reaction temperature during the heating process is configured based on the specific type of metal and its melting temperature, thereby ensuring that the various substances react fully.

[0065] Step 102: Stir the mixture during the heating process. After the reaction is complete, the reacted material is formed.

[0066] In one specific embodiment, the mixture is mechanically stirred during the heating process, wherein the stirring speed is 500 rpm to 1000 rpm and the stirring time is 0.5 h to 2 h.

[0067] Specifically, the mechanical stirring speed is set to 500 rpm, 520 rpm, 540 rpm, 550 rpm, 560 rpm, 580 rpm, 600 rpm, 620 rpm, 640 rpm, 650 rpm, 680 rpm, 700 rpm, 720 rpm, 740 rpm, 750 rpm, 760 rpm, 780 rpm, 800 rpm, 820 rpm, 840 rpm, 850 rpm, 860 rpm, 880 rpm, 900 rpm, 920 rpm, 940 rpm, 950 rpm, 960 rpm, 980 rpm, 1000 rpm, or a range of any two of the above values. The mechanical stirring time is set to 0.5h, 0.6h, 0.7h, 0.8h, 0.9h, 1h, 1.1h, 1.2h, 1.3h, 1.4h, 1.5h, 1.6h, 1.7h, 1.8h, 1.9h, 2h, or a range of any two of the above values.

[0068] With the above settings, the speed and stirring time of the mechanical stirring during the heating process can achieve a full reaction between the substances.

[0069] Step 103: Compress and cut the reacted material into tablets.

[0070] In this embodiment, the reacted material is placed on a tablet press and tableted by folding and pressing twice. The thickness of the reacted material after tableting is 90um to 110um, the tableting pressure is 2T to 4T, and the tableting holding time is 1min to 2min.

[0071] Specifically, the thickness of the tablet is set to 90um, 91um, 92um, 93um, 94um, 95um, 96um, 97um, 98um, 99um, 100um, 101um, 102um, 103um, 104um, 105um, 106um, 107um, 108um, 109um, 110um, or a range of any two of the above values.

[0072] The tablet compression pressure is set to 2T, 2.1T, 2.2T, 2.3T, 2.4T, 2.5T, 2.6T, 2.7T, 2.8T, 2.9T, 3T, 3.1T, 3.2T, 3.3T, 3.4T, 3.5T, 3.6T, 3.7T, 3.8T, 3.9T, 4T, or a range of any two of the above values.

[0073] The tablet holding time is set to 1 min, 1.1 min, 1.2 min, 1.3 min, 1.4 min, 1.5 min, 1.6 min, 1.7 min, 1.8 min, 1.9 min, 2 min, or a range of any two of the above values.

[0074] With the above settings, the reaction material can be tableted and the required negative electrode sheet can be prepared when different tableting pressures, tableting thicknesses, and holding times are used.

[0075] Furthermore, the post-reaction material after compression is cut using a cutting machine. Specifically, the maximum side length of the compressed negative electrode sheet can be cut to 12mm, 16mm, 18mm, 20mm, or any combination of two of the above values. When the negative electrode sheet is circular, the diameter of the cut negative electrode sheet is 2mm, 16mm, 18mm, 20mm, or any combination of two of the above values. Through the above settings, the post-reaction material after compression is cut into negative electrode sheets of the aforementioned different sizes.

[0076] It should be noted that the negative electrode sheet prepared in this embodiment can be matched with high-voltage positive electrode systems such as ternary, lithium iron manganese, and lithium cobalt oxide to prepare corresponding batteries. Furthermore, the negative electrode sheet prepared in this embodiment can be used as the negative electrode interface layer of sulfide all-solid-state lithium metal batteries. The three-dimensional alloy structure of the prepared negative electrode sheet can be used as the negative electrode material of sulfide all-solid-state lithium batteries and can exhibit stable interface performance when matched with sulfide electrolytes.

[0077] The scheme in this embodiment ensures sufficient lithium source during cycling by using the prepared negative electrode sheet, replenishing irreversible lithium loss, while the negative electrode sheet is stable for the electrolyte. By introducing a certain proportion of carbon fiber, a continuous electronic conductivity path can be formed in the structure, which is beneficial to improving the lithium ion diffusion kinetics in the electrode sheet. The stable three-dimensional structure formed by the combination of the negative electrode sheet and carbon materials can effectively alleviate the volume expansion problem of the battery during cycling and ensure the long-term cycle stability of the battery.

[0078] Corresponding to the above embodiments, this application provides a battery, which includes a negative electrode sheet prepared by the above-described method for preparing a negative electrode sheet.

[0079] Corresponding to the above embodiments, this application provides a vehicle that includes the aforementioned battery.

[0080] Example 1

[0081] Corresponding to the above embodiments, this embodiment provides a method for preparing a negative electrode sheet, the method including the following steps:

[0082] S1. Lithium metal and aluminum foil are added to a crucible at an atomic ratio of lithium atoms to aluminum atoms of 9:4, and then vapor-grown carbon fibers are added. The mass percentage of vapor-grown carbon fibers in the mixture is 5 wt%.

[0083] S2: Place the crucible containing the above mixture on a heating platform and heat it under an inert protective atmosphere, specifically nitrogen, to 500°C and hold it at that temperature for 1 hour.

[0084] S3: The mixture is mechanically stirred during the heating process at 1000 rpm for 1 hour. After the reaction is complete, the post-reaction material is formed.

[0085] S4: Place the reacted material into a tablet press and press it by folding it twice. Set the pressure of the tablet press to 4T and the holding time to 1min.

[0086] S5: The reacted material after compression is cut into pieces with a maximum side length of 12mm using a cutting machine to obtain a complete negative electrode sheet.

[0087] Example 2

[0088] Corresponding to the above embodiments, this embodiment provides a method for preparing a negative electrode sheet, the method including the following steps:

[0089] S1. Lithium metal and silver are added to a crucible in an atomic ratio of 1:1 between lithium atoms and silver atoms, and then vapor-grown carbon fibers are added. The mass percentage of vapor-grown carbon fibers in the mixture is 3 wt%.

[0090] S2: Place the crucible containing the above mixture on a heating platform and heat it under an inert protective atmosphere, specifically nitrogen, to 500°C and hold it at that temperature for 1 hour.

[0091] S3: The mixture is mechanically stirred during the heating process at a speed of 1000 rpm for 1 hour. After the reaction is completed, the reaction material is formed.

[0092] S4: Place the reacted material into a tablet press and press it by folding it twice. Set the pressure of the tablet press to 4T and the holding time to 1min.

[0093] S5: The reacted material after compression is cut into pieces with a maximum side length of 14mm using a cutting machine to obtain a complete negative electrode sheet.

[0094] Example 3

[0095] Corresponding to the above embodiments, this embodiment provides a method for preparing a negative electrode sheet, the method including the following steps:

[0096] S1. Lithium metal and tin are added to a crucible at an atomic ratio of 22:5 between lithium atoms and tin atoms, and then vapor-grown carbon fibers are added. The mass percentage of vapor-grown carbon fibers in the mixture is 3 wt%.

[0097] S2: Place the crucible containing the above mixture on a heating platform and heat it under an inert protective atmosphere, specifically nitrogen, to 700°C and hold for 1 hour.

[0098] S3: The mixture is mechanically stirred during the heating process at a speed of 1000 rpm for 1 hour. After the reaction is completed, the reaction material is formed.

[0099] S4: Place the reacted material into a tablet press and press it by folding it twice. Set the pressure of the tablet press to 4T and the holding time to 1min.

[0100] S5: The reacted material after compression is cut into pieces with a maximum side length of 16mm using a cutting machine to obtain a complete negative electrode sheet.

[0101] Comparative Example 1

[0102] Corresponding to the above embodiments, this embodiment provides a lithium anode, wherein the lithium anode is metallic lithium, and its battery performance is investigated.

[0103] Comparative Example 2

[0104] Corresponding to the above embodiments, this embodiment provides a lithium anode. The difference between this embodiment and embodiment 1 is that no lithiophilic nanomaterials are added in this embodiment. The rest of the preparation process is the same as in embodiment 1. The corresponding lithium anode is prepared in this embodiment, and its battery performance is investigated.

[0105] Comparative Example 3

[0106] Corresponding to the above embodiments, this embodiment provides a lithium anode. The difference between this embodiment and embodiment 1 is that the lithiophilic nanomaterial in this embodiment is a common lithiophilic metal. The rest of the preparation process is the same as in embodiment 1. This embodiment prepares the corresponding lithium anode and explores its battery performance.

[0107] like Figure 2 As shown, the negative electrode sheets prepared in Examples 1 to 3 were combined with NCM positive electrodes and LPSCl electrolytes to prepare mold batteries. Similarly, the negative electrodes prepared in Comparative Examples 1 to 3 were combined with NCM positive electrodes and LPSCl electrolytes to prepare corresponding mold batteries. The mold batteries were subjected to charge-discharge tests under the same environment and test conditions. The test conditions were as follows: the mold batteries were charged at a constant current of 0.1C to 4.2V, charged at a constant voltage to 0.05C, and discharged at a constant current of 0.1C to 2.8V. The battery charging capacity, discharging capacity, and impedance test results of the mold batteries were obtained. The specific test results are shown in Table 1.

[0108] Table 1. Test results of charging capacity, discharging capacity, and impedance of the mold battery.

[0109]

[0110] Based on the test results in Table 1, it can be concluded that the batteries prepared using the negative electrode sheets prepared by the preparation method in this application all achieved a first-cycle charging capacity of over 196 mAh / g, which is a significant improvement in performance compared to the batteries prepared using lithium negative electrodes in Comparative Examples 1 to 3. The first-cycle discharging capacity of the batteries corresponding to Examples 1 to 3 in this application all achieved a first-cycle discharging capacity of over 182 mAh / g, which is also a significant improvement in performance compared to the batteries prepared using lithium negative electrodes in Comparative Examples 1 to 3. This indicates that the carbon material used in the three-dimensional negative electrode sheet constructed in this application includes a vapor-grown carbon fiber structure. This carbon fiber is long and can be connected to the alloy during the reaction process, thereby ensuring better electronic conductivity within the structure and improving the lithium-ion diffusion kinetics in the electrode sheet.

[0111] Furthermore, by testing the pre-cycle impedance and post-50-cycle impedance of the batteries prepared in each embodiment, it can be concluded that the pre-cycle impedance of the batteries prepared by the method in this application is almost the same. However, after 50 cycles, the impedance of the battery corresponding to the negative electrode sheet prepared by the preparation method in this application is 95Ω, while the impedance of the battery corresponding to the lithium negative electrode prepared without the preparation method in this embodiment rises to more than 187Ω. This further verifies that by combining lithium metal, lithium-loving nanomaterials and carbon materials to construct a three-dimensional negative electrode sheet, the interface of the negative electrode material is stable when matched with the sulfide solid electrolyte, thereby ensuring the long-term cycle stability of the battery.

[0112] Furthermore, the test data in Table 1 also show that the negative electrode sheet prepared in this embodiment can be matched with high-voltage positive electrode systems such as ternary, lithium iron manganese, and lithium cobalt oxide to prepare corresponding batteries. Moreover, the negative electrode sheet prepared in this embodiment can be used as the negative electrode interface layer of sulfide all-solid-state lithium metal batteries. The three-dimensional alloy structure of the prepared negative electrode sheet can be used as the negative electrode material of sulfide all-solid-state lithium batteries and can exhibit stable interface performance when matched with sulfide electrolytes.

[0113] Although preferred embodiments have been described in this application, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of the embodiments of this application.

[0114] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the spirit and scope of this application. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include such modifications and variations.

Claims

1. A method for preparing a negative electrode, characterized in that, The method includes: Lithium metal, lithium-loving nanomaterials, and carbon materials are mixed to form a mixture, and the mixture is heated to a preset temperature for alloying. The mixture is stirred during the heating process, and after the reaction is complete, the reacted material is obtained. The reacted material is then compressed into tablets and cut.

2. The method for preparing the negative electrode sheet according to claim 1, characterized in that, The mass percentage of the carbon material in the mixture is 3 wt% to 5 wt%.

3. The method for preparing the negative electrode sheet according to claim 1 or 2, characterized in that, The particle size of the lithiophilic nanomaterial is 10 nm to 100 nm.

4. The method for preparing the negative electrode sheet according to claim 1 or 2, characterized in that, The lithiophilic nanomaterials include one or more of tin, aluminum, silver, and silicon; And / or, the carbon material includes one or more of vapor-grown carbon fibers, SP conductive carbon black, and Ketjen black.

5. The method for preparing the negative electrode sheet according to claim 4, characterized in that, The amounts of lithium metal and the lithiophilic nanomaterial satisfy the following conditions: When the lithiophilic nanomaterial includes the tin, the lithium metal and the tin are alloyed in an atomic ratio of (22:5) to (22:7) of lithium atoms to tin atoms; And / or, when the lithium-loving nanomaterial includes the aluminum, the aluminum is aluminum foil, and the lithium metal and the aluminum foil are alloyed in an atomic ratio of lithium atoms to aluminum atoms of (9:4) to (9:6); And / or, when the lithium-loving nanomaterial includes the silver, the lithium metal and the silver are alloyed in an atomic ratio of lithium atoms to silver atoms of (1:1) to (1:2); And / or, when the lithium-loving nanomaterial includes the silicon, the lithium metal and the silicon are alloyed in an atomic ratio of (1:1) to (1:2) of lithium atoms to silicon atoms.

6. The method for preparing the negative electrode sheet according to claim 4, characterized in that, The preset temperature satisfies the following conditions: When the lithiophilic nanomaterial includes tin, the preset temperature is set to 300℃~800℃; And / or, when the lithiophilic nanomaterial includes the aluminum and / or the silver, the preset temperature is set to 200℃~700℃; And / or, when the lithium-loving nanomaterial includes silicon, the preset temperature is set to 300℃~600℃.

7. The method for preparing the negative electrode sheet according to claim 1 or 2, characterized in that, The method further includes: During the heating process, the mixture is mechanically stirred at a speed of 500 rpm to 1000 rpm for a duration of 0.5 h to 2 h.

8. The method for preparing the negative electrode sheet according to claim 1 or 2, characterized in that, The method further includes: The thickness of the reacted material after tableting is 90µm to 110µm, the tableting pressure is 2T to 4T, and the tableting holding time is 1min to 2min.

9. A battery, characterized in that, The battery includes a negative electrode sheet, which is prepared by the method for preparing a negative electrode sheet according to any one of claims 1 to 8.

10. A vehicle, characterized in that, The vehicle includes the battery as described in claim 9.

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