Negative electrode active particle and preparation method therefor, and negative electrode sheet, battery and electronic device

Abstract

Provided in the present application are a negative electrode active particle and a preparation method therefor, and a negative electrode sheet, a battery and an electronic device. The negative electrode active particle of the present application comprises: a skeleton, which has a plurality of pores; and silicon particles, which are located in the plurality of pores, wherein there are gaps between the silicon particles and the inner walls of the pores, and the widths of the gaps range from 0.4 nm to 1 nm. The negative electrode active particle has a first X-ray diffraction pattern, and in the first X-ray diffraction pattern, the gaps and the silicon particles satisfy a relational expression 0.6≤Ia / Ib≤0.95, wherein Ia is the minimum value of diffraction intensity in the first X-ray diffraction pattern when 2θ ranges from 8.8° to 22°, Ib is the intensity of a diffraction peak of Si(111) in the first X-ray diffraction pattern when 2θ ranges from 28.2° to 28.5°, and 2θ is a diffraction angle. The negative electrode active particle of the present application has a low expansion rate and a high cyclic capacity retention rate.

Description

Negative electrode active particles and preparation method thereof, negative electrode sheet, battery and electronic equipment Technical Field

[0001] The present application relates to the field of electronics, and specifically to a negative electrode active particle and a preparation method thereof, a negative electrode plate, a battery and an electronic device. Background Art

[0002] Silicon has a high theoretical specific capacity (4200 mAh / g) and is the most promising negative electrode material for next-generation high-energy-density batteries. However, silicon itself undergoes significant expansion during lithium insertion, which can easily break up silicon particles and cause them to repeatedly form new solid electrolyte interphases (SEI) during charge and discharge. This accelerates electrolyte consumption and leads to a rapid decrease in the battery's cycle capacity retention rate. Summary of the Invention

[0003] The embodiments of the present application provide a negative electrode active particle having a lower expansion rate and a higher cycle capacity retention rate.

[0004] The first embodiment of the present application provides a negative electrode active particle, which includes:

[0005] a skeleton having a plurality of pores; and

[0006] Silicon particles, wherein the silicon particles are located in the plurality of pores, and there is a gap between the silicon particles and the inner wall of the pores, and the width of the gap ranges from 0.4 nm to 1 nm;

[0007] The negative electrode active particles have a first X-ray diffraction pattern, in which the gaps and the silicon particles satisfy the relationship 0.6≤Ia / Ib≤0.95, wherein Ia is the minimum value of the diffraction intensity in the range of 8.8° to 22° when 2θ is in the first X-ray diffraction pattern; Ib is the intensity of the diffraction peak of Si(111) in the range of 2θ being 28.2° to 28.5° when 2θ is in the first X-ray diffraction pattern; and 2θ is the diffraction angle.

[0008] A second embodiment of the present application provides a method for preparing negative electrode active particles, which includes:

[0009] providing a framework having a plurality of pores; and

[0010] A silicon source gas is introduced into the skeleton to deposit silicon particles in the multiple pores to obtain negative electrode active particles, wherein there is a gap between the silicon particles and the inner wall of the pore, and the gap ranges from 0.4 nm to 1 nm; the negative electrode active particles have a first X-ray diffraction pattern, and the gap and the silicon particles satisfy the relationship 0.6≤Ia / Ib≤0.95, wherein Ia is the minimum value of the diffraction intensity in the range of 8.8° to 22° when 2θ is in the first X-ray diffraction pattern; Ib is the intensity of the diffraction peak of Si(111) in the first X-ray diffraction pattern when 2θ is 28.2° to 28.5°.

[0011] A third embodiment of the present application provides a negative electrode plate, comprising:

[0012] a negative electrode current collector; and

[0013] A negative electrode active layer is provided on the surface of the negative electrode current collector, and the negative electrode active layer comprises the negative electrode active particles described in the first aspect of the present application or the negative electrode active particles prepared by the preparation method of the negative electrode active particles described in the second aspect of the present application.

[0014] A fourth aspect of the present application provides a battery, comprising:

[0015] electrolyte;

[0016] a positive electrode sheet, wherein the positive electrode sheet is at least partially immersed in the electrolyte;

[0017] a diaphragm, the diaphragm being located on one side of the positive electrode plate and at least partially immersed in the electrolyte, and

[0018] The negative electrode sheet described in the third aspect of the present application is arranged on the side of the separator away from the positive electrode sheet and is at least partially immersed in the electrolyte.

[0019] A fifth embodiment of the present application provides an electronic device, comprising: a device body; and

[0020] The battery described in the fourth aspect of the present application is used to power the device body. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0022] FIG1 is a schematic diagram of the structure of negative electrode active particles according to an embodiment of the present application.

[0023] FIG2 is an enlarged view of the dotted frame I in FIG1 of the present application.

[0024] FIG3 is a schematic structural diagram of negative electrode active particles according to another embodiment of the present application.

[0025] FIG4 is a schematic flow chart of a method for preparing negative electrode active particles according to an embodiment of the present application.

[0026] FIG5 is a schematic flow chart of a method for preparing negative electrode active particles according to another embodiment of the present application.

[0027] FIG6 is a schematic structural diagram of a negative electrode plate according to an embodiment of the present application.

[0028] FIG7 is a schematic structural diagram of a battery according to an embodiment of the present application.

[0029] FIG8 is a schematic cross-sectional view of a battery according to an embodiment of the present application along the AA direction in FIG7 .

[0030] FIG9 is a schematic structural diagram of a positive electrode plate according to an embodiment of the present application.

[0031] FIG10 is a first X-ray diffraction pattern of the negative electrode active particles of Example 1 of the present application.

[0032] FIG11 is a second X-ray diffraction pattern of the negative electrode active particles of Example 1 of the present application.

[0033] FIG12 is a schematic structural diagram of an electronic device according to an embodiment of the present application.

[0034] FIG13 is a schematic diagram of an exploded structure of an electronic device according to an embodiment of the present application.

[0035] FIG14 is a circuit block diagram of an electronic device according to an embodiment of the present application.

[0036] Explanation of the accompanying drawings: 100-negative electrode active particles, 10-skeleton, 11-pores, 20-silicon particles, 30-gaps, 40-carbon coating layer, 400-negative electrode plate, 410-negative electrode current collector, 420-negative electrode active layer, 500-battery, 510-positive electrode plate, 511-positive electrode current collector, 513-positive electrode active layer, 530-diaphragm, 550-housing, 570-end cover assembly, 600-electronic device, 610-device body, 611-display screen, 613-middle frame, 615-housing, 6151-light-transmitting part, 616-memory, 617-processor, 618-camera module. DETAILED DESCRIPTION

[0037] In order to enable those skilled in the art to better understand the present invention, the following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0038] The terms "first," "second," and the like in the specification and claims of this application and the accompanying drawings are used to distinguish between different objects, not to describe a particular order. Furthermore, the terms "including," "having," and any variations thereof, are intended to cover non-exclusive inclusions. For example, a process, method, system, product, or apparatus comprising a series of steps or elements is not limited to the listed steps or elements but may optionally include steps or elements not listed, or may optionally include other steps or elements inherent to the process, method, product, or apparatus.

[0039] This embodiment provides a negative electrode active particle, including:

[0040] a skeleton having a plurality of pores; and

[0041] Silicon particles, wherein the silicon particles are located in the plurality of pores, and there is a gap between the silicon particles and the inner wall of the pores, and the width of the gap ranges from 0.4 nm to 1 nm;

[0042] The negative electrode active particles have a first X-ray diffraction pattern, in which the gaps and the silicon particles satisfy the relationship 0.6≤Ia / Ib≤0.95, wherein Ia is the minimum value of the diffraction intensity in the range of 8.8° to 22° when 2θ is in the first X-ray diffraction pattern; Ib is the intensity of the diffraction peak of Si(111) in the range of 2θ being 28.2° to 28.5° when 2θ is in the first X-ray diffraction pattern; and 2θ is the diffraction angle.

[0043] Wherein, in the first X-ray diffraction pattern, the gap and the silicon particles satisfy the relationship 0.6≤Ia / Ib≤0.85.

[0044] The average pore size of the pores ranges from 0.8 nm to 4 nm.

[0045] The pore volume V of the skeleton 10 is in the range of 0.2 cm 3 / g to 1.5 cm 3 / g.

[0046] The negative electrode active particles have a second X-ray diffraction pattern after heat treatment. In the second X-ray diffraction pattern, the gap and the silicon particles satisfy the relationship: 0.5≤Ic / Id≤0.95, wherein Ic is the minimum value of the diffraction intensity in the range of 8.8° to 22° when 2θ is in the second X-ray diffraction pattern; Id is the intensity of the diffraction peak of Si(111) with 2θ of 28.2° to 28.5° in the second X-ray diffraction pattern; wherein the heat treatment includes heating to 700°C in an inert atmosphere for 2 hours, and cooling to room temperature.

[0047] Wherein, in the second X-ray diffraction pattern, the gap and the silicon particles satisfy the relationship: 0.5≤Ic / Id≤0.85.

[0048] Wherein, the negative electrode active particles further include a carbon coating layer, and the carbon coating layer is wrapped around the periphery of the skeleton.

[0049] Wherein, the thickness of the carbon coating layer ranges from 1 nm to 1000 nm.

[0050] Wherein, in the negative electrode active particles, the total mass fraction of silicon and carbon is greater than or equal to 90%, and the mass ratio of silicon to carbon is in the range of 1:99 to 95:5.

[0051] Wherein, the skeleton is a porous carbide, and the porous carbide includes at least one element of nitrogen, oxygen, fluorine, chlorine, titanium, zirconium, vanadium, molybdenum, tungsten, aluminum, and iron; in the negative electrode active particles, the mass fraction of silicon element ranges from 1% to 95%, and the total mass fraction of the porous carbide and the carbon coating layer ranges from 5% to 99%.

[0052] The median particle size D50 of the negative electrode active particles is in the range of 300 nm ≤ D50 ≤ 50 μm, the average particle size D1 of the silicon particles is in the range of 0.4 nm ≤ D1 ≤ 2 nm, and the specific surface area S of the negative electrode active particles is in the range of 0.1 m 2 / g≤S≤30m 2 / g.

[0053] The negative electrode active particles further include a doping element, and the doping element includes at least one of a non-metallic element and a metallic element.

[0054] The specific capacity of the negative electrode active particles ranges from 1700 mAh / g to 2000 mAh / g.

[0055] Wherein, the capacity retention rate of the negative electrode active particles after 50 cycles is greater than or equal to 95%.

[0056] This embodiment provides a method for preparing negative electrode active particles, comprising:

[0057] providing a framework having a plurality of pores; and

[0058] A silicon source gas is introduced into the skeleton to deposit silicon particles in the multiple pores to obtain negative electrode active particles, wherein there is a gap between the silicon particles and the inner wall of the pore, and the gap ranges from 0.4 nm to 1 nm; the negative electrode active particles have a first X-ray diffraction pattern, and the gap and the silicon particles satisfy the relationship 0.6≤Ia / Ib≤0.95, wherein Ia is the minimum value of the diffraction intensity in the range of 8.8° to 22° when 2θ is in the first X-ray diffraction pattern; Ib is the intensity of the diffraction peak of Si(111) in the first X-ray diffraction pattern when 2θ is 28.2° to 28.5°.

[0059] The step of introducing a silicon source gas into the skeleton to deposit silicon particles in the plurality of pores to obtain negative electrode active particles comprises:

[0060] At a temperature T1 of 400°C ≤ T1 ≤ 700°C, silicon source gas is introduced to deposit silicon particles in the plurality of pores, and the ratio t / V of the deposition time t of the silicon particles to the pore volume V of the skeleton is controlled to be in the range of 10 gh / cm 3 ≤t / V≤500gh / cm 3 .

[0061] The ratio m / V' of the mass m of the silicon source gas to the total volume V' of the plurality of pores of the skeleton is in the range of 0.05 g / cm 3 ≤m / V'≤1.8g / cm 3 .

[0062] This embodiment provides a negative electrode plate, comprising:

[0063] a negative electrode current collector; and

[0064] A negative electrode active layer is provided on the surface of the negative electrode current collector, and the negative electrode active layer comprises the negative electrode active particles provided in the above embodiment of the present application or the negative electrode active particles prepared by the preparation method of the negative electrode active particles provided in the above embodiment of the present application.

[0065] This embodiment provides a battery, comprising:

[0066] electrolyte;

[0067] a positive electrode sheet, wherein the positive electrode sheet is at least partially immersed in the electrolyte;

[0068] a diaphragm, the diaphragm being located on one side of the positive electrode plate and at least partially immersed in the electrolyte, and

[0069] The negative electrode plate provided in the above embodiment of the present application is arranged on a side of the separator away from the positive electrode plate and is at least partially immersed in the electrolyte.

[0070] This embodiment provides an electronic device, including:

[0071] the device itself; and

[0072] The battery provided in the above embodiment of the present application is used to power the device body.

[0073] The technical solutions in the embodiments of the present application will be described below with reference to the accompanying drawings.

[0074] It should be noted that, for the convenience of explanation, in the embodiments of the present application, the same reference numerals represent the same components, and for the sake of brevity, detailed descriptions of the same components are omitted in different embodiments.

[0075] With the continuous development of lithium-ion battery technology, lithium-ion batteries have advantages over other types of batteries such as lead-acid and nickel-cadmium batteries, such as high specific capacity, no memory effect, high operating voltage, fast charging speed, wide operating temperature range, long cycle life, small size, and light weight. Currently, lithium-ion batteries are widely used in mobile phones, laptops, electric vehicles, energy storage cabinets and other fields, and their application range is becoming increasingly wider.

[0076] Silicon has a high theoretical specific capacity (4200 mAh / g) and is the most promising negative electrode material for next-generation high-energy-density batteries. However, silicon itself undergoes significant expansion during lithium insertion, which can easily break up silicon particles and cause them to repeatedly form new solid electrolyte interphases (SEI) during charge and discharge. This accelerates electrolyte consumption and leads to a rapid decrease in the battery's cycle capacity retention rate.

[0077] Referring to Figures 1 and 2, an embodiment of the present application provides a negative electrode active particle 100, which includes a skeleton 10 and silicon particles 20, wherein the skeleton 10 has a plurality of pores 11; the silicon particles 20 are located in the plurality of pores 11, and there is a gap 30 between the silicon particles 20 and the inner wall of the pore 11, and the width of the gap 30 ranges from 0.4nm to 1nm; the negative electrode active particle 100 has a first X-ray diffraction pattern, in which the gap 30 and the silicon particles 20 satisfy the relationship 0.6≤Ia / Ib≤0.95, wherein Ia is the minimum value of the diffraction intensity in the first X-ray diffraction pattern with 2θ ranging from 8.8° to 22°; Ib is the intensity of the diffraction peak of Si(111) in the first X-ray diffraction pattern with 2θ ranging from 28.2° to 28.5°; 2θ is the diffraction angle.

[0078] The negative electrode active particles 100 of the present application can be used in batteries (such as lithium batteries). Specifically, the negative electrode active particles 100 can be used as active materials in the negative electrode active layer of the negative electrode sheet of the battery.

[0079] In the embodiments of the present application, when a numerical value range from a to b is involved, unless otherwise specified, it means that the numerical value can be any numerical value between a and b, including the endpoint numerical value a and the endpoint numerical value b.

[0080] It should be noted that, during the actual test process, the diffraction angle of the diffraction peak of Si(111) may shift, but is basically within the range of 28.2° to 28.5°.

[0081] It should be noted that Ib is the intensity of the diffraction peak of Si(111) in the first X-ray diffraction pattern.

[0082] It should be noted that the "pores 11" described in this application refer to the pores 11 of the skeleton 10 before the silicon particles 20 are filled. The "gaps 30" refer to the holes in the negative electrode active particles 100. That is, after the pores 11 of the skeleton 10 are filled with silicon particles 20, the holes formed in the portion not filled with silicon particles 20 are called gaps 30.

[0083] It should be noted that the skeleton 10 has a plurality of pores 11. It can be understood that the skeleton 10 is a porous structure. Optionally, the skeleton 10 can be, but is not limited to, at least one of a porous carbon skeleton 10, a porous carbide skeleton 10, and the like.

[0084] It should be noted that there are a plurality of gaps 30 , and the plurality of gaps 30 are dispersed in the negative electrode active particles 100 .

[0085] It can be understood that the negative electrode active particles 100 of the present application are silicon-based negative electrode materials or silicon-carbon composite materials.

[0086] It should be noted that in the first X-ray diffraction pattern, the diffraction intensity at a diffraction angle 2θ of 8.8° is the diffraction intensity of the gap 30 with a width of 0.4 nm in the first X-ray diffraction pattern. The diffraction intensity at a diffraction angle 2θ of 22° is the diffraction intensity of the gap 30 with a width of 1 nm in the first X-ray diffraction pattern. Ia is the minimum diffraction intensity of the gap 30 with a width ranging from 0.4 nm to 1 nm in the first X-ray diffraction pattern.

[0087] Specifically, the width of the gap 30 can be, but is not limited to, 0.4 nm, 0.5 nm, 0.6 nm, 0.7 nm, 0.8 nm, 0.9 nm, 1 nm, etc. If the width of the gap 30 is too small, the content of the gap 30 is too small. When the negative electrode active particles 100 are used in a battery, during the charge and discharge process of the battery, the gap 30 is insufficient to buffer the expansion of the silicon particles 20 during the lithium insertion process, thereby increasing the expansion rate of the negative electrode active particles 100, increasing the rate of electrolyte consumption, and reducing the cycle capacity retention rate of the battery. If the width of the gap 30 is too large, the content of the gap 30 is too large, resulting in a decrease in the energy density of the negative electrode active particles 100.

[0088] Specifically, Ia / Ib may be, but is not limited to, 0.6, 0.62, 0.65, 0.68, 0.7, 0.73, 0.75, 0.78, 0.8, 0.83, 0.85, 0.88, 0.9, 0.92, 0.95, etc. If Ia / Ib is too small, the content of the interstices 30 is too small. When the negative electrode active particles 100 are used in a battery, during the charge and discharge process of the battery, the interstices 30 are insufficient to buffer the expansion of the silicon particles 20 during lithium insertion, thereby increasing the expansion rate of the negative electrode active particles 100, making the negative electrode active particles 100 easily broken, and further, repeatedly forming a new SEI film on the surface of the negative electrode active particles 100, increasing the rate of electrolyte consumption and reducing the cycle capacity retention rate of the battery. If Ia / Ib is too large, the content of the interstices 30 is too large, resulting in a decrease in the energy density of the negative electrode active particles 100.

[0089] Furthermore, in the first X-ray diffraction pattern, the gaps 30 and the silicon particles 20 satisfy the relationship 0.6≤Ia / Ib≤0.85. This allows the negative electrode active particles 100 to have a lower expansion rate during lithium insertion, making them less prone to breakage during lithium insertion, thereby achieving a higher cycle capacity retention rate. Furthermore, the negative electrode active particles 100 also have a higher energy density.

[0090] The negative electrode active particles 100 of the embodiment of the present application include a skeleton 10 and silicon particles 20, the skeleton 10 has a plurality of pores 11, the silicon particles 20 are located in the plurality of pores 11, and there is a gap 30 between the silicon particles 20 and the inner wall of the pore 11, and the width of the gap 30 ranges from 0.4 nm to 1 nm; the negative electrode active particles 100 have a first X-ray diffraction pattern, the gap 30 and the silicon particles 20 satisfy the relationship 0.6≤Ia / Ib≤0.95, wherein Ia is the minimum value of the diffraction intensity in the range of 8.8° to 22° when 2θ is in the first X-ray diffraction pattern; Ib is the intensity of the diffraction peak of Si(111) in the first X-ray diffraction pattern when 2θ is 28.2° to 28.5°, and 2θ is the diffraction angle. When 0.6≤Ia / Ib≤0.95, there are enough gaps 30 of 0.4nm to 1.0nm in the negative electrode active particles 100, which can be used to buffer the expansion of the silicon particles 20 under the load of lithium insertion. The gaps 30 of 0.4nm to 1.0nm can provide sufficient buffer space for the expansion of silicon particles 20 with a diameter less than 2nm, reduce the damage of the expansion of the silicon particles 20 to the negative electrode active particles 100, and reduce the expansion of the negative electrode active particles 100, so that the negative electrode active particles 100 have a lower expansion rate. In addition, the negative electrode active particles 100 have a smaller expansion rate and less damage, which can reduce the repeated formation of SEI film on the surface of the negative electrode active particles 100 during the charge and discharge process, slow down the consumption of the electrolyte, and improve the cycle capacity retention rate of the negative electrode active particles 100.

[0091] Optionally, the average pore size of the pores 11 ranges from 0.8 nm to 4 nm. Specifically, the average pore size of the pores 11 may be, but is not limited to, 0.8 nm, 1.0 nm, 1.2 nm, 1.4 nm, 1.6 nm, 1.8 nm, 2.0 nm, 2.2 nm, 2.4 nm, 2.6 nm, 2.8 nm, 3.0 nm, 3.2 nm, 3.4 nm, 3.6 nm, 3.8 nm, 4 nm, etc.

[0092] Optionally, the pore size of the pores 11 of the skeleton 10 can be tested by nitrogen adsorption-desorption method.

[0093] Optionally, the pore volume V of the skeleton 10 is in the range of 0.2 cm 3 / g to 1.5cm 3 Specifically, the pore volume V of the skeleton 10 may be, but is not limited to, 0.2 cm 3 / g, 0.3cm 3 / g, 0.4cm 3 / g, 0.5cm 3 / g, 0.6cm 3 / g, 0.7cm 3 / g, 0.8cm 3 / g, 0.9cm 3 / g, 1.0cm 3 / g, 1.1cm 3 / g, 1.2cm 3 / g, 1.3cm 3 / g, 1.4cm 3 / g, 1.5cm 3 / g, etc. If the pore volume of the skeleton 10 is too small, it is insufficient to deposit sufficient silicon particles 20, thereby reducing the gram capacity of the negative electrode active particles 100; if the pore volume of the skeleton 10 is too large, there are too many pores, which will also reduce the energy density of the negative electrode active particles 100, and the proportion of the skeleton 10 is small and easy to break, thereby reducing the cycle performance of the negative electrode active particles 100.

[0094] The “pore volume” in this application refers to the total volume of the pores 11 possessed by the skeleton 10 per unit mass.

[0095] In some embodiments, the negative electrode active particles 100 have a second X-ray diffraction pattern after heat treatment, in which the gaps 30 and the silicon particles 20 satisfy the relationship: 0.5≤Ic / Id≤0.95, where Ic is the minimum value of the diffraction intensity in the range of 8.8° to 22° when 2θ is in the second X-ray diffraction pattern; and Id is the intensity of the diffraction peak of Si(111) with 2θ being 28.2° to 28.5° in the second X-ray diffraction pattern; wherein the heat treatment comprises heating to 700°C for 2 hours in an inert atmosphere, and cooling to room temperature.

[0096] Optionally, the inert atmosphere may be, but is not limited to, at least one of a nitrogen atmosphere, an argon atmosphere, and the like.

[0097] Optionally, the heat treatment is performed under vacuum conditions.

[0098] Alternatively, in other embodiments, the heat treatment temperature may be, but is not limited to, 650° C. to 750° C., such as 650° C., 680° C., 700° C., 725° C., 750° C., etc. If the heat treatment temperature is too low, amorphous silicon cannot be transformed into crystalline silicon, and a silicon crystal peak cannot be formed in the second X-ray diffraction pattern. If the temperature is too high, silicon and carbon are likely to react to form silicon carbide.

[0099] Specifically, Ic / Id can be, but is not limited to, 0.5, 0.52, 0.55, 0.58, 0.6, 0.62, 0.65, 0.68, 0.7, 0.73, 0.75, 0.78, 0.8, 0.83, 0.85, 0.88, 0.9, 0.92, 0.95, etc. If Ic / Id is too small, the content of the gap 30 is too small. When the negative electrode active particles 100 are applied to a battery, during the charge and discharge process of the battery, the gap 30 is insufficient to buffer the expansion of the silicon particles 20 during the lithium insertion process, resulting in an excessive expansion rate of the negative electrode active particles 100, an increase in the rate of electrolyte consumption, and a decrease in the cycle capacity retention rate of the battery. In addition, the negative electrode active particles 100 are prone to generate Li during the lithium insertion process. 15 Si4 crystal phase, during the formation of the crystal phase, the negative electrode active particles 100 will cause higher internal stress and produce greater volume changes, which will deteriorate the cycle performance of the negative electrode active particles 100; if Ic / Id is too large, the content of the gap 30 will be too large, which will reduce the energy density of the negative electrode active particles 100.

[0100] In this embodiment, by making 0.6≤Ia / Ib≤0.95, the Li 15 The formation of Si4 crystal phase can reduce the volume change of negative electrode active particles 100 during lithium insertion, and better weaken the Li 15 The formation of the Si4 crystal phase causes the negative electrode active particles 100 to break, so that the negative electrode active particles 100 have a more stable silicon structure, thereby having a higher cycle capacity retention rate; in addition, the negative electrode active particles 100 can also have a higher energy density.

[0101] Furthermore, in the second X-ray diffraction pattern, the gaps 30 and the silicon particles 20 satisfy the relationship: 0.5≤Ic / Id≤0.85. This allows the negative electrode active particles 100 to have a lower expansion rate during lithium insertion, making them less prone to breakage during lithium insertion, thereby achieving a higher cycle capacity retention rate. Furthermore, the negative electrode active particles 100 also have a higher energy density.

[0102] Furthermore, in the second X-ray diffraction pattern, the gaps 30 and the silicon particles 20 satisfy the relationship: 0.5≤Ic / Id≤0.75. This allows the negative electrode active particles 100 to have a lower expansion rate during lithium insertion, making them less prone to breakage during lithium insertion, thereby achieving a higher cycle capacity retention rate. Furthermore, the negative electrode active particles 100 also have a higher energy density.

[0103] Referring to FIG. 3 , in some embodiments, the negative electrode active particle 100 further includes a carbon coating layer 40 , and the carbon coating layer 40 wraps around the outer periphery of the skeleton 10 .

[0104] It can be understood that the carbon coating layer 40 is used to seal the pores 11 of the skeleton 10 to prevent the silicon particles 20 from being exposed on the surface of the negative electrode active particles 100 . The skeleton 10 and the silicon particles 20 are both wrapped in the carbon coating layer 40 .

[0105] When silicon particles 20 are exposed on the surface of the negative electrode active particles 100, they come into direct contact with the electrolyte, causing side reactions that consume active silicon and electrolyte, reducing the specific capacity of the silicon particles 20 and causing the cycle capacity retention of the negative electrode active particles 100 to continuously decrease with increasing cycle number. In this embodiment, the negative electrode active particles 100 have a carbon coating 40. When used in a battery, this prevents direct contact between the silicon particles 20 and the electrolyte, thereby avoiding a large number of side reactions and enabling the negative electrode active particles 100 to have a higher cycle capacity retention, particularly high-temperature cycling performance.

[0106] Optionally, the carbon coating layer 40 has a thickness ranging from 1 nm to 1000 nm. Specifically, the thickness of the carbon coating layer 40 may be, but is not limited to, 1 nm, 3 nm, 5 nm, 8 nm, 10 nm, 15 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 150 nm, 200 nm, 300 nm, 400 nm, 500 nm, 600 nm, 700 nm, 800 nm, 900 nm, 1000 nm, etc. In this embodiment, if the thickness of the carbon coating layer 40 is too thick, the carbon content in the negative electrode active particles 100 is too high, the proportion of silicon decreases, and the specific capacity of the negative electrode active particles 100 is reduced; if the thickness of the carbon coating layer 40 is too thin, the carbon coating layer 40 does not completely cover the skeleton 10, which easily leads to incomplete isolation of the silicon particles 20 from the electrolyte, increased side reactions, and reduced cycle capacity retention rate of the negative electrode active particles 100.

[0107] Furthermore, the thickness of the carbon coating layer 40 is in the range of 2 nm to 900 nm, which can make the negative electrode active particles 100 have a higher specific capacity and a higher cycle capacity retention rate.

[0108] Furthermore, the thickness of the carbon coating layer 40 is in the range of 2 nm to 500 nm, which can make the negative electrode active particles 100 have a higher specific capacity and a higher cycle capacity retention rate.

[0109] Furthermore, the thickness of the carbon coating layer 40 is in the range of 5 nm to 100 nm, which can make the negative electrode active particles 100 have a higher specific capacity and a higher cycle capacity retention rate.

[0110] In some embodiments, in the negative electrode active particles 100 , the total mass fraction of silicon and carbon is greater than or equal to 90%, and the mass ratio of silicon to carbon is in a range of 1:99 to 95:5.

[0111] Specifically, the total mass fraction of silicon and carbon in the negative electrode active particles 100 may be, but is not limited to, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, etc. If the total mass fraction of silicon and carbon in the negative electrode active particles 100 is too high, the energy density of the negative electrode active particles 100 is reduced.

[0112] Specifically, the mass ratio of silicon to carbon in the negative electrode active particles 100 can be, but is not limited to, 1:99, 1:90, 1:80, 1:70, 1:50, 1:30, 1:10, 1:1, 3:1, 5:1, 7:1, 10:1, 13:1, 15:1, 17:1, 95:5, etc. If the mass ratio of silicon to carbon in the negative electrode active particles 100 is too low, the active material in the negative electrode active particles 100 is too low, thereby reducing the specific capacity of the negative electrode active particles 100. If the mass ratio of silicon to carbon in the negative electrode active particles 100 is too high, the skeleton 10 is insufficient to support the expansion of the silicon particles 20 during lithium insertion in the negative electrode active particles 100, causing the negative electrode active particles 100 to easily rupture, thereby affecting the cycle performance of the battery using the negative electrode active particles 100. When the mass ratio of silicon to carbon in the negative electrode active particles 100 is within this range, the negative electrode active particles 100 can have a higher specific capacity and a higher cycle capacity retention rate.

[0113] Furthermore, the mass ratio of silicon to carbon in the negative electrode active particles 100 is in the range of 2:8 to 7:3. When the mass ratio of silicon to carbon in the negative electrode active particles 100 is within this range, the negative electrode active particles 100 can have both a high specific capacity and a high cycle capacity retention rate.

[0114] In some embodiments, the negative electrode active particles 100 further include a doping element, and the doping element includes at least one of a non-metallic element and a metallic element.

[0115] Optionally, the non-metallic element includes at least one of oxygen, sulfur, nitrogen, phosphorus, and hydrogen. Oxygen doping can alleviate the expansion of the silicon particles 20 during the lithium insertion process of the negative electrode active particles 100, thereby reducing the expansion rate of the negative electrode active particles 100 and improving the cycle performance of the battery using the negative electrode active particles 100. Sulfur, nitrogen, and phosphorus doping can improve the conductivity of the negative electrode active particles 100, thereby improving the kinetic performance of the battery using the negative electrode active particles 100. Hydrogen can maintain a certain amorphous state of silicon, which is beneficial to the cycle performance of the battery using the negative electrode active particles 100.

[0116] Optionally, the metal element includes one of lithium, aluminum, magnesium, titanium, sodium, copper, and iron. Lithium doping has a lithium replenishing effect, which is beneficial for improving the initial efficiency of the battery using the negative electrode active particles 100. Aluminum, magnesium, titanium, sodium, copper, and iron can be used as components of the skeleton 10. For example, porous carbides of these metal elements can be used as the skeleton 10 to improve the conductivity of the negative electrode active particles 100, thereby improving the dynamic performance of the battery using the negative electrode active particles 100.

[0117] In other embodiments, the skeleton 10 is a porous carbide, and the porous carbide includes at least one element selected from nitrogen, oxygen, fluorine, chlorine, titanium, zirconium, vanadium, molybdenum, tungsten, aluminum, and iron; in the negative electrode active particles 100, the mass fraction of silicon element ranges from 1% to 95%, and the total mass fraction of the porous carbide and the carbon coating layer 40 ranges from 5% to 99%.

[0118] It is understood that the porous carbide includes carbon and at least one element selected from nitrogen, oxygen, fluorine, chlorine, titanium, zirconium, vanadium, molybdenum, tungsten, aluminum, and iron. The porous carbide has high strength, which can better prevent the negative electrode active particles 100 from breaking during the lithium insertion process, thereby improving the cycle capacity retention rate of the battery using the negative electrode active particles 100. In addition, the porous carbide has high conductivity, which can improve the kinetic performance of the negative electrode active particles 100, thereby improving the kinetic performance of the battery using the negative electrode active particles 100.

[0119] In a specific embodiment, the porous carbide may be, but is not limited to, titanium carbide (TiC).

[0120] Specifically, the mass fraction of silicon in the negative electrode active particles 100 may be, but is not limited to, 1%, 3%, 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 95%, etc.

[0121] Specifically, in the negative electrode active particles 100, the total mass fraction of the porous carbide and the carbon coating layer 40 can be, but is not limited to, 5%, 8%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 95%, 99%, etc.

[0122] In this embodiment, if the mass fraction of silicon is too low and the total mass fraction of the porous carbide and the carbon coating layer 40 is too high, the active material in the negative electrode active particles 100 is too little, thereby reducing the specific capacity of the negative electrode active particles 100; if the mass fraction of silicon is too high and the total mass fraction of the porous carbide and the carbon coating layer 40 is too low, then during the lithium insertion process of the negative electrode active particles 100, the skeleton 10 is insufficient to support the expansion of the silicon particles 20, making the negative electrode active particles 100 easily broken, thereby affecting the cycle performance of the battery using the negative electrode active particles 100.

[0123] Furthermore, the skeleton 10 is a porous carbide containing at least one element selected from nitrogen, oxygen, fluorine, chlorine, titanium, zirconium, vanadium, molybdenum, tungsten, aluminum, and iron. The mass fraction of silicon in the negative electrode active particles 100 ranges from 20% to 70%, and the total mass fraction of the porous carbide and the carbon coating layer 40 ranges from 30% to 80%. This allows the negative electrode active particles 100 to have both a high specific capacity and a high cycle capacity retention rate.

[0124] In some embodiments, the median particle size D50 of the negative electrode active particles 100 is in the range of 300 nm ≤ D50 ≤ 50 μm.

[0125] Specifically, the median particle size D50 of the negative electrode active particles 100 may be, but is not limited to, 300 nm, 400 nm, 500 nm, 600 nm, 700 nm, 800 nm, 1 μm, 3 μm, 5 μm, 7 μm, 10 μm, 13 μm, 15 μm, 18 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, etc.

[0126] In this embodiment, if the median particle size D50 of the negative electrode active particles 100 is too large, when the negative electrode active particles 100 are used in a lithium battery, the lithium ion transmission path within the negative electrode active particles 100 increases, increasing the lithium ion transmission impedance and resulting in poor kinetics. If the median particle size D50 of the negative electrode active particles 100 is too small, the specific surface area of ​​the negative electrode active particles 100 increases, the contact area between the negative electrode active particles 100 and the electrolyte increases, and the SEI film increases. During the battery's charge and discharge cycles, the repeated destruction and growth of the SEI film consumes more electrolyte, which can easily reduce the battery's cycle capacity retention rate. When the median particle size D50 of the negative electrode active particles 100 is within the range of 300nm≤D50≤50μm, the negative electrode active particles 100 can have good kinetic performance and a high cycle capacity retention rate.

[0127] Furthermore, the median particle size D50 of the negative electrode active particles 100 is in the range of 1 μm ≤ D50 ≤ 20 μm. When the median particle size of the negative electrode active particles 100 is within this range, the negative electrode active particles 100 can have good kinetic performance and high cycle capacity retention.

[0128] Furthermore, the median particle size D50 of the negative electrode active particles 100 is in the range of 3 μm ≤ D50 ≤ 15 μm. When the median particle size of the negative electrode active particles 100 is within this range, the negative electrode active particles 100 can have good kinetic performance and high cycle capacity retention.

[0129] Furthermore, the median particle size D50 of the negative electrode active particles 100 is in the range of 5 μm ≤ D50 ≤ 12 μm. When the median particle size of the negative electrode active particles 100 is within this range, the negative electrode active particles 100 can have good kinetic performance and high cycle capacity retention.

[0130] Optionally, the range of the average particle size D1 of the silicon particles 20 is: 0.4nm≤D1≤2nm. Specifically, the average particle size D1 of the silicon particles 20 can be, but is not limited to, 0.4nm, 0.5nm, 0.6nm, 0.7nm, 0.8nm, 0.9nm, 1.0nm, 1.1nm, 1.2nm, 1.3nm, 1.4nm, 1.5nm, 1.6nm, 1.7nm, 1.8nm, 1.9nm, 2.0nm, etc. If the average particle size of the silicon particles 20 is too small, silicon is in an atomic state and cannot form a silicon phase, which reduces the embedding of lithium ions and further reduces the specific capacity of the negative electrode active particles 100; if the average particle size of the silicon particles 20 is too large, it is easy to generate Li during the process of lithium embedding of the negative electrode active particles 100. 15The Si4 crystal phase and phase transition cause higher internal stress and greater volume change in the negative electrode active particles 100, making the negative electrode active particles 100 more susceptible to breakage and reducing the cycle capacity retention of the negative electrode active particles 100. When the average particle size D1 of the silicon particles 20 is 0.4nm≤D1≤2nm, the silicon particles 20 are sufficiently small to minimize the pressure on them during lithium insertion and removal, reducing the breakage of the negative electrode active particles 100 and ensuring the stability of the silicon structure, thereby further improving the cycle performance of the negative electrode active particles 100.

[0131] Furthermore, the average particle size D1 of the silicon particles 20 is in the range of 0.5 nm ≤ D1 ≤ 1.8 nm. When the average particle size of the silicon particles 20 is in this range, it is less likely to generate Li during the lithium insertion process of the negative electrode active particles 100. 15 The Si4 crystal phase can better improve the structural stability of the negative electrode active particles 100, so that the negative electrode active particles 100 have a higher cycle capacity retention rate.

[0132] Furthermore, the average particle size D1 of the silicon particles 20 is in the range of 0.7 nm ≤ D1 ≤ 1.8 nm. When the average particle size of the silicon particles 20 is in this range, it is less likely to generate Li during the lithium insertion process of the negative electrode active particles 100. 15 The Si4 crystal phase can better improve the structural stability of the negative electrode active particles 100, so that the negative electrode active particles 100 have a higher cycle capacity retention rate.

[0133] Optionally, the average particle size of the silicon particles 20 can be measured in the following manner: the negative electrode active particles 100 are heated to 700 degrees in an inert atmosphere (such as nitrogen or argon) for 2 hours, and then cooled to room temperature, and a second X-ray diffraction pattern of the heat-treated negative electrode active particles 100 is obtained. The half-width of the diffraction peak of Si (111) near 2θ = 28.4° in the second X-ray diffraction pattern is used to calculate the average particle size of the silicon particles 20 by the Scherrer method.

[0134] Optionally, the specific surface area S of the negative electrode active particles 100 is in the range of 0.1 m 2 / g≤S≤30m 2 Specifically, the specific surface area S of the negative electrode active particles 100 may be, but is not limited to, 0.1 m 2 / g, 0.3m 2 / g, 0.5m 2 / g, 0.8m 2 / g、1m 2 / g、3m 2 / g、5m 2 / g、8m2 / g、10m 2 / g、12m 2 / g、14m 2 / g、16m 2 / g、18m 2 / g, 20m 2 / g、22m 2 / g、24m 2 / g、26m 2 / g、28m 2 / g、30m 2 / g, etc. When the specific surface area of ​​the negative electrode active particles 100 is small, the contact area between the negative electrode active particles 100 and the electrolyte can be better reduced, thereby avoiding excessive consumption of electrolyte during the cycle and reducing the cycle capacity retention rate of the negative electrode particles; however, when the specific surface area of ​​the negative electrode active particles 100 is too small, the size of the negative electrode active particles 100 is large. The larger size increases the transmission path of lithium ions inside the negative electrode active particles 100, increases the impedance of lithium ion transmission, and deteriorates the kinetic performance of the negative electrode active particles 100; if the specific surface area of ​​the negative electrode active particles 100 is too large, when applied to a battery, the contact area between the negative electrode active particles 100 and the electrolyte increases, and the SEI film increases. During the charge and discharge cycle of the battery, the repeated destruction and growth of the SEI film consumes more electrolyte, which easily reduces the cycle capacity retention rate of the battery.

[0135] It should be noted that, unless otherwise specified, the "specific surface area" in this application refers to the BET specific surface area, which is the total surface area per unit mass of a material. "BET" is the initials of three scientists: Brunauer, Emmett, and Teller.

[0136] Furthermore, the specific surface area S of the negative electrode active particles 100 is in the range of: 1m 2 / g≤S≤20m 2 This can make the negative electrode active particles 100 have a higher cycle capacity retention rate.

[0137] Furthermore, the specific surface area S of the negative electrode active particles 100 is in the range of: 1m 2 / g≤S≤10m 2 This can make the negative electrode active particles 100 have a higher cycle capacity retention rate.

[0138] In some embodiments, the specific capacity of the negative electrode active particles 100 ranges from 1700 mAh / g to 2000 mAh / g. Specifically, the specific capacity of the negative electrode active particles 100 may be, but is not limited to, 1700 mAh / g, 1750 mAh / g, 1800 mAh / g, 1850 mAh / g, 1900 mAh / g, 1950 mAh / g, 2000 mAh / g, etc.

[0139] In some embodiments, the capacity retention rate of the negative electrode active particles 100 after 50 cycles is greater than or equal to 95%. Furthermore, the capacity retention rate of the negative electrode active particles 100 after 50 cycles is greater than or equal to 96%. Still further, the capacity retention rate of the negative electrode active particles 100 after 50 cycles is greater than or equal to 97%. Specifically, the capacity retention rate of the negative electrode active particles 100 after 50 cycles can be, but is not limited to, 95%, 95.5%, 96%, 96.5%, 97%, 97.5%, 98.5%, 99%, etc.

[0140] The negative electrode active particles 100 of the embodiments of the present application can be prepared by the methods described in the following embodiments of the present application. In addition, they can also be prepared by other methods. The preparation methods of the embodiments of the present application are merely one or more preparation methods of the negative electrode active particles 100 of the present application and should not be understood as limiting the negative electrode active particles 100 provided in the embodiments of the present application.

[0141] Referring to FIG. 4 , the present embodiment further provides a method for preparing negative electrode active particles 100 , which includes:

[0142] S201, providing a skeleton 10, wherein the skeleton 10 has a plurality of pores 11; and

[0143] For detailed discussion of the skeleton 10 and the pores 11 , please refer to the description of the relevant parts of the above embodiment, which will not be repeated here.

[0144] S202, introducing a silicon source gas into the skeleton 10 to deposit silicon particles 20 in the plurality of pores 11 to obtain negative electrode active particles 100, wherein a gap 30 is provided between the silicon particles 20 and the inner wall of the pore 11, and the range of the gap 30 is 0.4 nm to 1 nm; the negative electrode active particles 100 have a first X-ray diffraction pattern, and the gap 30 and the silicon particles 20 satisfy the relationship 0.6≤Ia / Ib≤0.95, wherein Ia is the minimum value of the diffraction intensity in the range of 8.8° to 22° when 2θ is in the first X-ray diffraction pattern; and Ib is the intensity of the diffraction peak of Si(111) in the first X-ray diffraction pattern when 2θ is 28.2° to 28.5°.

[0145] Optionally, the silicon source gas may be, but is not limited to, at least one of monosilane, disilane, dichlorosilane, trichlorosilane, and the like.

[0146] Optionally, for descriptions of other features of the negative electrode active particles 100 , silicon particles 20 , etc., please refer to the descriptions of the corresponding parts of the above embodiments, which will not be repeated here.

[0147] The negative electrode active particles 100 prepared by the preparation method of the negative electrode active particles 100 of the embodiment of the present application include a skeleton 10 and silicon particles 20, the skeleton 10 has a plurality of pores 11, the silicon particles 20 are located in the plurality of pores 11, and there is a gap 30 between the silicon particles 20 and the inner wall of the pore 11, and the width of the gap 30 ranges from 0.4nm to 1nm; the negative electrode active particles 100 have a first X-ray diffraction pattern, and the gap 30 and the silicon particles 20 satisfy the relationship 0.6≤Ia / Ib≤0.95, wherein Ia is the minimum value of the diffraction intensity in the range of 8.8° to 22° when 2θ is in the first X-ray diffraction pattern; Ib is the intensity of the diffraction peak of Si(111) in the first X-ray diffraction pattern when 2θ is 28.2° to 28.5°, and 2θ is the diffraction angle. When 0.6≤Ia / Ib≤0.95, there are enough gaps 30 of 0.4nm to 1.0nm in the negative electrode active particles 100, which can be used to buffer the expansion of the silicon particles 20 under the load of lithium insertion. The gaps 30 of 0.4nm to 1.0nm can provide sufficient buffer space for the expansion of silicon particles 20 with a diameter less than 2nm, reduce the damage of the expansion of the silicon particles 20 to the negative electrode active particles 100, and reduce the expansion of the negative electrode active particles 100, so that the negative electrode active particles 100 have a lower expansion rate. In addition, the negative electrode active particles 100 have a smaller expansion rate and less damage, which can reduce the repeated formation of SEI film on the surface of the negative electrode active particles 100 during the charge and discharge process, slow down the consumption of the electrolyte, and improve the cycle capacity retention rate of the negative electrode active particles 100.

[0148] In some embodiments, the step of introducing a silicon source gas into the skeleton 10 to deposit silicon particles 20 in the plurality of pores 11 to obtain negative electrode active particles 100 includes:

[0149] At a temperature T1 of 400°C ≤ T1 ≤ 700°C, silicon source gas is introduced to deposit silicon particles 20 in the plurality of pores 11, and the ratio t / V of the deposition time t of the silicon particles 20 to the pore volume V of the skeleton 10 is controlled to be in the range of 10 gh / cm 3 ≤t / V≤500gh / cm 3 .

[0150] Optionally, the silicon source gas may be mixed with a carrier gas before being introduced into the skeleton 10 to deposit the silicon particles 20 .

[0151] Optionally, the carrier gas may be, but is not limited to, at least one of nitrogen and argon.

[0152] Specifically, the temperature T1 at which the silicon particles 20 are deposited can be, but is not limited to, 400°C, 430°C, 450°C, 480°C, 500°C, 530°C, 550°C, 580°C, 600°C, 630°C, 650°C, 680°C, 700°C, etc. If the temperature T1 at which the silicon particles 20 are deposited is too high, the reaction rate of the silicon source gas will be too fast, and the silicon source gas will not have time to enter the pores 11 of the skeleton 10 before it begins to deposit. The deposition of silicon on the surface of the skeleton 10 will cause the negative electrode active particles 100 to intercalate lithium. When silicon expands, it will not be restricted by the space of the skeleton 10, which will increase the expansion rate of the entire negative electrode active particles 100 and deteriorate the cycle performance of the battery using the negative electrode active particles 100. In addition, when silicon is deposited on the surface, the size of the silicon will not be restricted by the size of the pores 11 in the skeleton 10 and will continue to grow. Excessive silicon size will result in the generation of Li+ when intercalating lithium. 15 The Si4 phase further deteriorates the cycle performance of the battery using the negative electrode active particles 100; if the temperature T1 at which the silicon particles 20 are deposited is too low, the silicon source gas is difficult to decompose into silicon and deposit, and silicon particles 20 cannot be formed in the pores 11 of the skeleton 10.

[0153] Specifically, the ratio t / V of the deposition time t of the silicon particles 20 to the pore volume V of the skeleton 10 may be, but is not limited to, 10 gh / cm 3 、15gh / cm 3 、20gh / cm 3 、25gh / cm 3 、30gh / cm 3 、40gh / cm 3 、50gh / cm 3 、80gh / cm 3 、100gh / cm 3 、120gh / cm 3 、140gh / cm 3 、160gh / cm 3 、180gh / cm 3 、200gh / cm 3 、220gh / cm 3 、240gh / cm 3 、260gh / cm 3 、280gh / cm 3 、300gh / cm 3 、320gh / cm 3 、340gh / cm 3 、360gh / cm 3、380gh / cm 3 、400gh / cm 3 、420gh / cm 3 、440gh / cm 3 、460gh / cm 3 、480gh / cm 3 、500gh / cm 3 Etc. If the ratio t / V of the deposition time t of the silicon particles 20 to the pore volume V of the skeleton 10 is too small, the deposition of the silicon particles 20 may be uneven, and the silicon particles 20 may not be deposited in some pores 11 of the skeleton 10, thereby increasing the expansion rate of the negative electrode active particles 100 during the lithium insertion process, which is not conducive to the cycle performance of the negative electrode active particles 100; if the ratio t / V of the deposition time t of the silicon particles 20 to the pore volume V of the skeleton 10 is too large, the preparation cost of the negative electrode active particles 100 may be increased. When the ratio t / V of the deposition time t of the silicon particles 20 to the pore volume V of the skeleton 10 is 10gh / cm 3 ≤t / V≤500gh / cm 3 When the silicon particles 20 are deposited in the pores 11 of the skeleton 10, the silicon particles 20 can be deposited more uniformly, allowing the silicon particles 20 to be deposited in each pore 11 as much as possible, thereby better reducing the expansion rate of the negative electrode active particles 100 during the lithium insertion process. In addition, the negative electrode active particles 100 can have a lower preparation cost.

[0154] Furthermore, the ratio t / V of the deposition time t of the silicon particles 20 to the pore volume V of the skeleton 10 is in the range of 10 gh / cm 3 ≤t / V≤400gh / cm 3 This allows the silicon particles 20 to be deposited more evenly within the pores 11 of the skeleton 10 , allowing the silicon particles 20 to be deposited in each pore 11 as much as possible, thereby better reducing the expansion rate of the negative electrode active particles 100 during the lithium insertion process. In addition, it can also reduce the preparation cost of the negative electrode active particles 100.

[0155] Furthermore, the ratio t / V of the deposition time t of the silicon particles 20 to the pore volume V of the skeleton 10 is in the range of 10 gh / cm 3 ≤t / V≤300gh / cm 3 This allows the silicon particles 20 to be deposited more evenly within the pores 11 of the skeleton 10 , allowing the silicon particles 20 to be deposited in each pore 11 as much as possible, thereby better reducing the expansion rate of the negative electrode active particles 100 during the lithium insertion process. In addition, it can also reduce the preparation cost of the negative electrode active particles 100.

[0156] Furthermore, the ratio t / V of the deposition time t of the silicon particles 20 to the pore volume V of the skeleton 10 is in the range of 10 gh / cm 3 ≤t / V≤200gh / cm 3 This allows the silicon particles 20 to be deposited more evenly within the pores 11 of the skeleton 10 , allowing the silicon particles 20 to be deposited in each pore 11 as much as possible, thereby better reducing the expansion rate of the negative electrode active particles 100 during the lithium insertion process. In addition, it can also reduce the preparation cost of the negative electrode active particles 100.

[0157] Furthermore, the ratio t / V of the deposition time t of the silicon particles 20 to the pore volume V of the skeleton 10 is in the range of 10 gh / cm 3 ≤t / V≤100gh / cm 3 This allows the silicon particles 20 to be deposited more evenly within the pores 11 of the skeleton 10 , allowing the silicon particles 20 to be deposited in each pore 11 as much as possible, thereby better reducing the expansion rate of the negative electrode active particles 100 during the lithium insertion process. In addition, it can also reduce the preparation cost of the negative electrode active particles 100.

[0158] Optionally, the deposition time t of the silicon particles 20 is in the range of 1h≤t≤100h. Specifically, the deposition time t of the silicon particles 20 may be, but is not limited to, 1h, 3h, 5h, 8h, 10h, 15h, 20h, 25h, 30h, 35h, 40h, 50h, 60h, 70h, 80h, 90h, 100h, etc. If the deposition time t of the silicon particles 20 is too long, it is easy for the silicon particles 20 to grow too large, the formed silicon particles 20 are too large, and the size of the silicon phase in the negative electrode active particles 100 is too large, so that the negative electrode active particles 100 are more likely to generate Li when lithium is inserted. 15 Si4 crystal phase, during the formation of the crystal phase, the negative electrode active particles 100 will cause higher internal stress and produce greater volume changes, which will deteriorate the cycle performance of the negative electrode active particles 100; if the deposition time t of the silicon particles 20 is too short, the silicon content in the negative electrode active particles 100 will be reduced, thereby reducing the specific capacity of the negative electrode active particles 100.

[0159] Optionally, the pore volume V of the skeleton 10 is in the range of 0.2 cm 3 / g to 1.5cm 3 Specifically, the pore volume V of the skeleton 10 may be, but is not limited to, 0.2 cm 3 / g, 0.3cm 3 / g, 0.4cm 3 / g, 0.5cm 3 / g, 0.6cm 3 / g, 0.7cm3 / g, 0.8cm 3 / g, 0.9cm 3 / g, 1.0cm 3 / g, 1.1cm 3 / g, 1.2cm 3 / g, 1.3cm 3 / g, 1.4cm 3 / g, 1.5cm 3 / g, etc. If the pore volume of the skeleton 10 is too small, it is insufficient to deposit sufficient silicon particles 20, thereby reducing the gram capacity of the negative electrode active particles 100; if the pore volume of the skeleton 10 is too large, there will be too many pores 11, which will also reduce the energy density of the negative electrode active particles 100. The proportion of the skeleton 10 is small and it is easy to break, thereby reducing the cycle performance of the negative electrode active particles 100.

[0160] In some embodiments, the ratio m / V' of the mass m of the silicon source gas to the total volume V' of the plurality of pores 11 of the skeleton 10 is in the range of 0.05 g / cm 3 ≤m / V'≤1.8g / cm 3 .

[0161] It should be noted that “the total volume V′ of the plurality of pores 11 of the skeleton 10 ” refers to the sum of the volumes of the pores 11 of all the skeletons 10 in the reaction system.

[0162] For example, the total volume V' of the plurality of pores 11 of the skeleton 10 = the weight m' of the skeleton 10 participating in the reaction x the pore volume V of the skeleton 10. That is, V' = m'V.

[0163] Specifically, the ratio m / V' of the mass m of the silicon source gas to the total volume V' of the plurality of pores 11 of the skeleton 10 may be, but is not limited to, 0.05 g / cm 3 , 0.08g / cm 3 , 0.1g / cm 3 , 0.15g / cm 3 , 0.2g / cm 3 , 0.25g / cm 3 , 0.3g / cm 3 , 0.4g / cm 3 , 0.5g / cm 3 , 0.6g / cm 3 , 0.8g / cm 3 , 1.0g / cm 3 , 1.2g / cm 3 , 1.4 / cm 3 , 1.6g / cm 3 , 1.8g / cm 3Etc. If the ratio m / V' of the mass m of the silicon source gas to the total volume V' of the multiple pores 11 of the skeleton 10 is too small, the energy density of the negative electrode active particles 100 obtained will be too low; if the ratio m / V' of the mass m of the silicon source gas to the total volume V' of the multiple pores 11 of the skeleton 10 is too large, the mass fraction of silicon in the negative electrode active particles 100 obtained will be too high, which will increase the expansion rate of the negative electrode active particles 100. During the lithium insertion process of the negative electrode active particles 100, the skeleton 10 is insufficient to support the expansion of the silicon particles 20, making the negative electrode active particles 100 easy to rupture, affecting the cycle performance of the battery using the negative electrode active particles 100. When the ratio m / V' of the mass m of the silicon source gas to the total volume V' of the multiple pores 11 of the skeleton 10 is 0.05g / cm 3 ≤m / V'≤1.8g / cm 3 When the negative electrode active particles 100 are added, the negative electrode active particles 100 can have a higher energy density and a lower expansion rate, so that the battery using the negative electrode active particles 100 has better cycle performance.

[0164] Furthermore, the ratio m / V' of the mass m of the silicon source gas to the total volume V' of the plurality of pores 11 of the skeleton 10 is in the range of 0.2 g / cm 3 ≤m / V'≤1.8g / cm 3 This allows the negative electrode active particles 100 to have a higher energy density and a lower expansion rate, thereby allowing the battery using the negative electrode active particles 100 to have better cycle performance.

[0165] Furthermore, the ratio m / V' of the mass m of the silicon source gas to the total volume V' of the plurality of pores 11 of the skeleton 10 is in the range of 0.5 g / cm 3 ≤m / V'≤1.8g / cm 3 This allows the negative electrode active particles 100 to have a higher energy density and a lower expansion rate, thereby allowing the battery using the negative electrode active particles 100 to have better cycle performance.

[0166] Referring to FIG. 5 , the present embodiment further provides a method for preparing negative electrode active particles 100 , which includes:

[0167] S301, providing a skeleton 10, wherein the skeleton 10 has a plurality of pores 11;

[0168] S302, introducing a silicon source gas into the skeleton 10 to deposit silicon particles 20 in the plurality of pores 11, thereby obtaining negative electrode active particles 100, wherein a gap 30 is provided between the silicon particles 20 and the inner wall of the pore 11, and the gap 30 is in the range of 0.4 nm to 1 nm; the negative electrode active particles 100 have a first X-ray diffraction pattern, and the gap 30 and the silicon particles 20 satisfy the relationship 0.6≤Ia / Ib≤0.95, wherein Ia is the minimum value of the diffraction intensity in the range of 8.8° to 22° when 2θ is in the first X-ray diffraction pattern; and Ib is the intensity of the diffraction peak of Si(111) in the range of 2θ being 28.2° to 28.5° when 2θ is in the first X-ray diffraction pattern; and

[0169] For a detailed description of S301 and S302 , please refer to the description of the corresponding parts of the above embodiment, which will not be repeated here.

[0170] S303 , forming a carbon coating layer 40 on the surface of the skeleton 10 having the silicon particles 20 .

[0171] Optionally, an organic gas is introduced into the skeleton 10 having the silicon particles 20 , and chemical vapor deposition (ie, carbon deposition) is performed at 500° C. to 900° C. to form a carbon coating layer 40 on the surface of the skeleton 10 having the silicon particles 20 .

[0172] Optionally, the organic gas may be, but is not limited to, at least one of acetylene, methane, and the like.

[0173] Optionally, the deposition temperature may be, but is not limited to, 500° C., 550° C., 600° C., 650° C., 700° C., 750° C., 800° C., 850° C., 900° C., etc. The chemical vapor deposition time may be 1 to 3 hours, such as 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours, etc.

[0174] Please refer to Figure 6. The embodiment of the present application also provides a negative electrode plate 400, which includes a negative electrode current collector 410 and a negative electrode active layer 420. The negative electrode active layer 420 is arranged on the surface of the negative electrode current collector 410. The negative electrode active layer 420 includes the negative electrode active particles 100 described in the embodiment of the present application or the negative electrode active particles 100 prepared by the preparation method of the negative electrode active particles 100 described in the embodiment of the present application.

[0175] Optionally, the negative electrode active layer 420 may be disposed on one surface or multiple surfaces of the negative electrode current collector 410 .

[0176] Optionally, the negative electrode current collector 410 may be, but is not limited to, a copper sheet.

[0177] Optionally, the negative electrode active layer 420 further includes a negative electrode conductive agent and a negative electrode binder. It can be understood that the negative electrode active particles 100, the negative electrode conductive agent and the negative electrode binder are uniformly dispersed.

[0178] Optionally, the negative electrode conductive agent may be, but is not limited to, conductive carbon black (SP for short), acetylene black, carbon nanotubes, carbon fibers, and graphite.

[0179] Optionally, the negative electrode binder may be, but is not limited to, at least one of polyacrylic acid (PAA), polyvinylidene fluoride (PVDF), polyamide (PA), polyacrylonitrile (PAN), polyacrylate, polyvinylether, polymethyl methacrylate (PMMA), polyhexafluoropropylene, and styrene butadiene rubber (SBR).

[0180] Optionally, the mass fraction of the negative electrode binder in the negative electrode active layer 420 ranges from 2 wt% to 4 wt%. Specifically, the mass fraction of the negative electrode binder in the negative electrode active layer 420 may be, but is not limited to, 2 wt%, 2.5 wt%, 3 wt%, 3.5 wt%, 4 wt%, etc. If the mass fraction of the negative electrode binder is too low, the negative electrode active layer 420 may easily pulverize or slag; if the mass fraction of the negative electrode binder is too high, the energy density of the negative electrode sheet 400 may be reduced.

[0181] Referring to Figures 7 and 8, an embodiment of the present application further provides a battery 500, which includes: an electrolyte, a positive electrode plate 510, a diaphragm 530 and a negative electrode plate 400 of an embodiment of the present application, wherein the positive electrode plate 510 is at least partially immersed in the electrolyte; the diaphragm 530 is located on one side of the positive electrode plate 510 and is at least partially immersed in the electrolyte; the negative electrode plate 400 is arranged on a side of the diaphragm 530 away from the positive electrode plate 510 and is at least partially immersed in the electrolyte.

[0182] It can be understood that the positive electrode sheet 510 , the separator 530 and the negative electrode sheet 400 are stacked in sequence.

[0183] The battery 500 of the embodiment of the present application can be, but is not limited to, a lithium-ion secondary battery 500, a lithium-ion primary battery 500, a lithium-sulfur battery 500, a sodium-lithium-ion battery 500, a sodium-ion battery 500, or a magnesium-ion battery 500.

[0184] 9 , optionally, the positive electrode sheet 510 includes a positive electrode current collector 511 and a positive electrode active layer 513 covering the surface of the positive electrode current collector 511. It is understood that the positive electrode active layer 513 may cover one surface or two opposite surfaces of the positive electrode current collector 511.

[0185] The positive electrode current collector 511 may be, but is not limited to, an aluminum sheet.

[0186] Optionally, the positive electrode active layer 513 includes a positive electrode active material, a positive electrode conductor, and a positive electrode binder.

[0187] Optionally, the positive electrode active material may be, but is not limited to, at least one of lithium iron phosphate, lithium cobalt oxide, and the like.

[0188] Optionally, the positive electrode conductive agent may be, but is not limited to, at least one of conductive carbon black, acetylene black, carbon nanotubes, carbon fibers, graphene, and the like.

[0189] Optionally, the positive electrode binder may be, but is not limited to, at least one of polyvinylidene fluoride (PVDF), polyamide (PA), polyacrylonitrile (PAN), polyacrylate, polyvinylether, polymethyl methacrylate (PMMA), polyhexafluoropropylene, and styrene butadiene rubber (SBR).

[0190] Optionally, the mass fraction of the positive electrode binder in the positive electrode active layer 513 ranges from 2 wt% to 4 wt%. Specifically, the mass fraction of the positive electrode binder in the positive electrode active layer 513 may be, but is not limited to, 2 wt%, 2.5 wt%, 3 wt%, 3.5 wt%, 4 wt%, etc. If the mass fraction of the positive electrode binder is too low, the positive electrode active layer 513 may easily pulverize or slag; if the mass fraction of the positive electrode binder is too high, the energy density of the positive electrode sheet 510 may be reduced.

[0191] Optionally, the electrolyte includes an electrolyte salt, an organic solvent and a film-forming additive.

[0192] Optionally, the electrolyte salt is a lithium salt, which may include but is not limited to at least one of lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium bis(oxalatoborate) (LiBOB), LiODFP, lithium difluorooxalatoborate (LiODFB), lithium difluorophosphate (LiPO2F2), lithium trifluoromethanesulfonate (CF3SO3Li), etc.

[0193] Optionally, in the electrolyte, the molar concentration M of the lithium salt is in the range of 0.7 mol / L≤M≤1.4 mol / L. In the electrolyte, the molar concentration M of the lithium salt may be, but is not limited to, 0.7 mol / L, 0.8 mol / L, 0.9 mol / L, 1.0 mol / L, 1.1 mol / L, 1.2 mol / L, 1.3 mol / L, 1.4 mol / L, and the like. In the electrolyte, if the molar concentration M of the lithium salt is too small, the concentration of free ions in the electrolyte is too small, which reduces the conductivity of the electrolyte and thus reduces the kinetic performance of the battery; in the electrolyte, if the molar concentration M of the lithium salt is too large, it is easy for a portion of the electrolyte salt to remain undissociated, and the viscosity of the electrolyte will increase, which in turn reduces the conductivity of the electrolyte and also reduces the kinetic performance of the battery. In the electrolyte, when the molar concentration M of the lithium salt is in the range of 0.7 mol / L≤M≤1.4 mol / L, the electrolyte can have a higher conductivity, thereby enabling the battery to have better kinetic performance.

[0194] Optionally, the organic solvent includes at least one of a cyclic carbonate and a chain carbonate. Cyclic carbonate has a high dielectric constant and high ionic conductivity, and can form a stable SEI film on the surface of the negative electrode plate 400, but its viscosity is relatively high. Chain carbonate has a lower viscosity than cyclic carbonate, better electrochemical stability, and can improve the low-temperature performance of the electrolyte. Therefore, when a mixed solvent of cyclic carbonate and chain carbonate is used, the electrolyte can have a more suitable viscosity and low-temperature stability, and the battery 500 using the electrolyte can also form a better film.

[0195] Optionally, the cyclic carbonate may include but is not limited to at least one of ethylene carbonate (EC), propylene carbonate (PC), etc. The dielectric constant of ethylene carbonate is much greater than that of propylene carbonate, and ethylene carbonate can better promote the formation of SEI film.

[0196] Optionally, the chain carbonate may include but is not limited to at least one of dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), and the like.

[0197] Optionally, the organic solvent includes at least one of a cyclic carbonate and a chain carbonate. Cyclic carbonate has a high dielectric constant and high ionic conductivity, and can form a stable SEI film on the surface of the negative electrode plate 400, but its viscosity is relatively high. Chain carbonate has a lower viscosity than cyclic carbonate, better electrochemical stability, and can improve the low-temperature performance of the electrolyte. Therefore, when a mixed solvent of cyclic carbonate and chain carbonate is used, the electrolyte can have a more suitable viscosity and low-temperature stability, and the battery 500 using the electrolyte can also form a better film.

[0198] Optionally, the cyclic carbonate may include but is not limited to at least one of ethylene carbonate (EC), propylene carbonate (PC), etc. The dielectric constant of ethylene carbonate is much greater than that of propylene carbonate, and ethylene carbonate can better promote the formation of SEI film.

[0199] Optionally, the chain carbonate may include but is not limited to at least one of dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), and the like.

[0200] Optionally, the film-forming additive includes at least one of fluoroethylene carbonate (FEC), vinyl sulfate (PST), vinylene carbonate (VC), vinyl ethylene carbonate (VEC), sulfur tris(trimethylsilyl) phosphate, tris(trimethylsilyl) borate, adiponitrile, succinonitrile, and 1,3,6-hexanetrinitrile.

[0201] Optionally, the mass fraction of the film-forming additive ranges from 1.5% to 3%. Specifically, the mass fraction of the film-forming additive may be, but is not limited to, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2%, 2.1%, 2.2%, 2.3%, 2.4%, 2.5%, 2.6%, 2.7%, 2.8%, 2.9%, 3%, etc. The film-forming additive may be used to promote the formation of an interfacial film on at least one of the positive electrode sheet 510 and the negative electrode sheet 400 and maintain the stability of the interfacial film.

[0202] Optionally, the diaphragm 530 may be, but is not limited to, at least one of a polypropylene film (PP), a polyethylene film (PE), a ceramic film, etc. Optionally, the thickness of the diaphragm 530 is 14 μm to 18 μm. Specifically, the thickness of the diaphragm 530 may be, but is not limited to, 14 μm, 14.5 μm, 15 μm, 15.5 μm, 16 μm, 16.5 μm, 17 μm, 17.5 μm, and 18 μm.

[0203] In some embodiments, the battery 500 further includes a housing 550 and an end cap assembly 570. The housing 550 and the end cap assembly 570 enclose a housing space for accommodating the electrolyte, the positive electrode sheet 510, the separator 530, and the negative electrode sheet 400. The end cap assembly 570 includes a positive electrode post (not shown) and a negative electrode post (not shown). The positive electrode post is electrically connected to the positive electrode sheet 510, and the negative electrode post is electrically connected to the negative electrode sheet 400. The positive electrode post and the negative electrode post are used to electrically connect the battery 500 to an electrical device or other battery 500.

[0204] It can be understood that the battery 500 described in this embodiment is merely a form of the battery 500 used by the negative electrode plate 400, and should not be understood as a limitation on the battery 500 provided in this application, nor should it be understood as a limitation on the negative electrode plate 400 provided in each embodiment of this application.

[0205] After testing, the battery 500 made of the negative active particles 100 of the embodiment of the present application has a cycle capacity retention rate of greater than or equal to 92.2% after 400 cycles at 25°C. Specifically, the battery 500 made of the negative active particles 100 of the embodiment of the present application has a cycle capacity retention rate of greater than or equal to 92.2% after 400 cycles at 25°C, but is not limited to greater than or equal to 92.2%, greater than or equal to 93%, greater than or equal to 94%, greater than or equal to 95%, greater than or equal to 96%, greater than or equal to 97%, greater than or equal to 98%, greater than or equal to 99%, etc.

[0206] After testing, the battery 500 made of the negative active particles 100 of the embodiment of the present application has a thickness expansion rate of less than 5.4% after 400 cycles at 25°C. Specifically, the battery 500 made of the negative active particles 100 of the embodiment of the present application has a thickness expansion rate of less than 5.4% after 400 cycles at 25°C. Specifically, the battery 500 made of the negative active particles 100 of the embodiment of the present application has a thickness expansion rate of but not limited to less than or equal to 5.4%, less than or equal to 5%, less than or equal to 4.5%, less than or equal to 4%, less than or equal to 3.5%, less than or equal to 3%, less than or equal to 2.5%, less than or equal to 2%, etc.

[0207] The negative electrode active particles 100 and the battery 500 of the present application are further described below through specific examples.

[0208] Example 1

[0209] The negative electrode active particles 100 of this embodiment are prepared by the following steps:

[0210] 1) 1000 g of porous carbon (skeleton 10) was placed in a vapor deposition furnace. The average pore size of the pores 11 was 1.8 nm, and the pore volume V of the skeleton 10 was 0.8 cm3 / g;

[0211] 2) nitrogen was introduced and heated to 500°C, followed by introduction of a mixed gas of silane (silicon source gas) and nitrogen (carrier gas) for 20 hours, with a total mass of 1000 g of silane introduced;

[0212] 3) Heating to 650° C. and introducing acetylene gas (organic gas) for 2 hours, and then cooling to obtain the negative electrode active particles 100 .

[0213] Example 2

[0214] The negative electrode active particles 100 of this embodiment are prepared by the following steps:

[0215] 1) 1000 g of porous carbon (skeleton 10) was placed in a vapor deposition furnace. The average pore size of the pores 11 was 1.8 nm, and the pore volume V of the skeleton 10 was 1.0 cm 3 / g;

[0216] 2) nitrogen was introduced and heated to 500°C, followed by introduction of a mixed gas of silane (silicon source gas) and nitrogen (carrier gas), and the reaction was carried out for 30 hours. The total mass of silane introduced was 1000 g;

[0217] 3) Heating to 650° C. and introducing acetylene gas (organic gas) for 3 hours, and then cooling to obtain the negative electrode active particles 100 .

[0218] Example 3

[0219] The negative electrode active particles 100 of this embodiment are prepared by the following steps:

[0220] 1) 1000 g of porous carbon (skeleton 10) was placed in a vapor deposition furnace. The average pore size of the pores 11 was 1.8 nm, and the pore volume V of the skeleton 10 was 0.8 cm 3 / g;

[0221] 2) Nitrogen was introduced and heated to 500°C, followed by introduction of a mixed gas of silane (silicon source gas) and nitrogen (carrier gas) for 20 hours, with a total mass of 800 g of silane introduced;

[0222] 3) Heating to 650° C. and introducing acetylene gas (organic gas) for 3 hours, and then cooling to obtain the negative electrode active particles 100 .

[0223] Example 4

[0224] The negative electrode active particles 100 of this embodiment are prepared by the following steps:

[0225] 1) 1000 g of porous carbon (skeleton 10) was placed in a vapor deposition furnace. The average pore size of the pores 11 was 3.2 nm, and the pore volume V of the skeleton 10 was 1.2 cm 3 / g;

[0226] 2) nitrogen was introduced and heated to 500°C, followed by introduction of a mixed gas of silane (silicon source gas) and nitrogen (carrier gas), and the reaction was carried out for 18 hours. The total mass of silane introduced was 1000 g;

[0227] 3) Heating to 650° C. and introducing acetylene gas (organic gas) for 3 hours, and then cooling to obtain the negative electrode active particles 100 .

[0228] Example 5

[0229] The negative electrode active particles 100 of this embodiment are prepared by the following steps:

[0230] 1) 1000 g of porous TiC (skeleton 10) was placed in a vapor deposition furnace. The average pore size of the pores 11 was 1.6 nm, and the pore volume V of the skeleton 10 was 0.8 cm 3 / g;

[0231] 2) nitrogen was introduced and heated to 500°C, followed by introduction of a mixed gas of silane (silicon source gas) and nitrogen (carrier gas) for 20 hours, with a total mass of 1000 g of silane introduced;

[0232] 3) Heating to 650° C. and introducing acetylene gas (organic gas) for 2 hours, and then cooling to obtain the negative electrode active particles 100 .

[0233] Comparative Example 1

[0234] The negative electrode active particles 100 of this comparative example were prepared by the following steps:

[0235] 1) 1000 g of porous carbon (skeleton 10) was placed in a vapor deposition furnace. The average pore size of the pores 11 was 1.8 nm, and the pore volume V of the skeleton 10 was 0.8 cm 3 / g;

[0236] 2) nitrogen was introduced and heated to 500°C, followed by introduction of a mixed gas of silane (silicon source gas) and nitrogen (carrier gas), and the reaction was carried out for 6 hours. The total mass of silane introduced was 1000 g;

[0237] 3) Heating to 650° C. and introducing acetylene gas (organic gas) for 2 hours, and then cooling to obtain the negative electrode active particles 100 .

[0238] Comparative Example 2

[0239] The negative electrode active particles 100 of this comparative example were prepared by the following steps:

[0240] 1) 1000 g of porous carbon (skeleton 10) was placed in a vapor deposition furnace. The average pore size of the pores 11 was 1.8 nm, and the pore volume V of the skeleton 10 was 0.8 cm 3 / g;

[0241] 2) introducing nitrogen and heating at 1.2 to 500° C., then introducing a mixed gas of silane (silicon source gas) and nitrogen (carrier gas), and reacting for 20 hours. The total mass of silane introduced was 1500 g;

[0242] 3) Heating to 650° C. and introducing acetylene gas (organic gas) for 2 hours, and then cooling to obtain the negative electrode active particles 100 .

[0243] Comparative Example 3

[0244] The negative electrode active particles 100 of this comparative example were prepared by the following steps:

[0245] 1) 1000 g of porous carbon (skeleton 10) was placed in a vapor deposition furnace. The average pore size of the pores 11 was 5 nm, and the pore volume V of the skeleton 10 was 1.3 cm 3 / g;

[0246] 2) nitrogen was introduced and heated to 500°C, followed by introduction of a mixed gas of silane (silicon source gas) and nitrogen (carrier gas), and the reaction was carried out for 20 hours. The total mass of silane introduced was 2000 g;

[0247] 3) Heating to 650° C. and introducing acetylene gas (organic gas) for 2 hours, and then cooling to obtain the negative electrode active particles 100 .

[0248] The following tests were performed on the negative electrode active particles 100 obtained in Examples 1 to 5 and Comparative Examples 1 to 3:

[0249] 1) X-ray powder diffraction (XRD) was performed on the negative electrode active particles 100 in each Example and Comparative Example using CuKα radiation at a wavelength of 0.154 nm. A first X-ray diffraction pattern was obtained for each Example and Comparative Example. Ia and Ib were obtained from the first X-ray diffraction pattern, and Ia / Ib was calculated. The Ia / Ib ratios for each Example and Comparative Example are shown in Table 1 below. The first X-ray diffraction pattern of the negative electrode active particles 100 of Example 1 is shown in Figure 10 .

[0250] 2) The negative electrode active particles 100 in each embodiment and comparative example were heated to 700°C for 2 hours under an inert atmosphere (N2, Ar, vacuum, etc.), then cooled to room temperature and subjected to CuKα ray XRD testing at a wavelength of 0.154 nm. A second X-ray diffraction pattern was obtained for each embodiment and comparative example. Ia and Ib were obtained from the second X-ray diffraction pattern, and Ic / Id was calculated. The Ic / Id for each embodiment and comparative example is shown in Table 1 below. The half-width at half maximum (FWHM) of the diffraction peak of Si(111) near 2θ=28.4° in the second X-ray diffraction pattern was used to determine the average particle size D1 of the silicon particles 20 as 7.852 / (FWHM*cosθ). The Ic / Id and D1 for each embodiment and comparative example are shown in Table 1 below. The second X-ray diffraction pattern of the negative electrode active particles 100 of Example 1 is shown in Figure 11.

[0251] 3) Preparation of button half-cell 500: The negative electrode active particles 100 are mixed with conductive carbon black (SP), carbon nanotubes (CNT), and polyacrylic acid (PAA) in a mass ratio of 80:8:2:10 to form a slurry. The slurry is coated on copper foil (i.e., the negative electrode current collector), vacuum dried, and roller-pressed to obtain a negative electrode sheet. The negative electrode sheet is then assembled into a button half-cell 500, using a lithium sheet as the counter electrode.

[0252] 4) The button half-cell 500 was subjected to capacity division and cycle testing: the cell was discharged at a discharge rate of 0.1C to 5 mV, allowed to stand for 5 minutes, then discharged at a discharge rate of 0.05C to 5 mV, allowed to stand for 5 minutes, then discharged at a discharge rate of 0.02C to 5 mV, allowed to stand for 10 minutes, and charged at 0.1C to 1.5 V. This cycle was repeated 50 times. The cycle capacity retention rate after 50 cycles was calculated. The 50 cycle capacity retention rates of the button half-cell 500 composed of the negative electrode active particles 100 of each embodiment and comparative example are shown in Table 2 below.

[0253] 5) The negative electrode active particles 100 were mixed with graphite, PAA, and CNT in a mass ratio of 10:87:2.8:0.2 to form a slurry, which was then applied to the negative electrode current collector, dried at 100°C, and rolled with a pressure of 5t to obtain a negative electrode sheet. The positive electrode active material lithium cobalt oxide was mixed with conductive carbon black (conductive agent) and PVDF binder in a mass ratio of 98:1:1 to form a slurry, which was then applied to the positive electrode current collector, dried, and rolled to obtain a positive electrode sheet. The negative electrode sheet, positive electrode sheet, and separator were fabricated into a wound battery 500, which was then encapsulated with aluminum-plastic film, dried, injected, formed, re-encapsulated, and capacity divided to obtain the battery 500, which was then subjected to a 25°C cycle test. The cycle capacity retention and thickness expansion rate of the battery 500 formed with the negative electrode active particles 100 of each embodiment and comparative example after 400 cycles are shown in Table 3 below.

[0254] 6) Calculation of the thickness expansion rate of the battery 500: Thickness expansion rate of the battery 500 = (thickness of the battery 500 after n cycles - initial thickness of the battery 500) / initial thickness of the battery 500 × 100%.

[0255] The measurement results of the embodiments and comparative examples are shown in Table 1, Table 2 and Table 3 below.

[0256] Table 1

[0257] Table 2

[0258] Table 3

[0259] From the test data of Examples 1 to 5, it can be seen that the Ia / Ib of the negative electrode active particles 100 of Examples 1 to 5 are all between 0.6 and 0.95, and the button-type half-cells 500 prepared using the negative electrode active particles 100 of each embodiment have a high cycle capacity retention rate, and their cycle capacity retention rates are all above 95.8%. In addition, the negative electrode active particles 100 of each embodiment have a high specific capacity. The first lithium insertion specific capacity of the negative electrode active particles 100 of each embodiment is greater than or equal to 1784mAh / g, and the first lithium removal specific capacity of the negative electrode active particles 100 of each embodiment is greater than or equal to 1620mAh / g. This shows that the negative electrode active particles 100 of the present application have a high lithium insertion specific capacity, and these specific capacities are highly reversible (i.e., have a high lithium removal specific capacity). The test data from Comparative Examples 1 to 3 show that when the Ia / Ib ratio of the negative electrode active particles 100 is less than 0.6, the cycle capacity retention rate of the coin-type half-cell 500 prepared from the negative electrode active particles 100 is significantly reduced. This indicates that when the Ia / Ib ratio of the negative electrode active particles 100 is between 0.6 and 0.95, the negative electrode active particles 100 have a higher cycle capacity retention rate and can maintain a higher specific capacity.

[0260] The test data from Examples 1 to 5 show that the Ic / Id ratios of the negative electrode active particles 100 of Examples 1 to 5 range from 0.5 to 0.95. The coin-type half-cells 500 produced using the negative electrode active particles 100 from each example all exhibit high cycle capacity retention rates, exceeding 95.8%. Furthermore, the negative electrode active particles 100 of each example exhibit high specific capacities, with the initial lithium insertion capacity of the negative electrode active particles 100 of each example being greater than or equal to 1784 mAh / g, and the initial lithium removal capacity of the negative electrode active particles 100 of each example being greater than or equal to 1620 mAh / g. The test data from Comparative Examples 1 to 3 show that when the Ic / Id ratio of the negative electrode active particles 100 is less than 0.5, the cycle capacity retention of the coin-type half-cells 500 produced using the negative electrode active particles 100 is significantly reduced. This indicates that when the Ic / Id of the negative electrode active particles 100 is between 0.5 and 0.95, the negative electrode active particles 100 have a higher cycle capacity retention rate and can maintain a higher specific capacity.

[0261] The test data from Examples 1 to 5 show that when the average particle size D1 of the silicon particles 20 in the negative electrode active particles 100 of Examples 1 to 5 is between 0.4 nm and 2 nm, the coin-type half-cells 500 produced from these negative electrode active particles 100 all exhibit high cycle capacity retention rates, exceeding 95.8%. Furthermore, the negative electrode active particles 100 of each embodiment exhibit high specific capacities, with the initial lithium insertion capacity of each embodiment greater than or equal to 1784 mAh / g, and the initial lithium removal capacity of each embodiment greater than or equal to 1620 mAh / g. The test data from Comparative Examples 1 to 3 show that when the average particle size D1 of the silicon particles 20 in the negative electrode active particles 100 is greater than 2 nm, the cycle capacity retention of the coin-type half-cells 500 produced from these negative electrode active particles 100 is significantly reduced. This indicates that when the average particle size D1 of the silicon particles 20 in the negative electrode active particles 100 is between 0.4 nm and 2 nm, the negative electrode active particles 100 have a higher cycle capacity retention rate and can maintain a higher specific capacity.

[0262] As shown in Table 3, when the Ia / Ib ratio of the negative electrode active particles 100 is between 0.6 and 0.95, the batteries 500 using the negative electrode active particles 100 (i.e., the batteries 500 prepared from the negative electrode active particles 100 of Examples 1 to 5) all have a high cycle capacity retention rate after 400 cycles, and the cycle capacity retention rate is all above 92.2%. Moreover, as Ia / Ib increases, the 400 cycle capacity retention rate of the batteries 500 using the negative electrode active particles 100 gradually increases. When the Ia / Ib ratio of the negative electrode active particles 100 is less than 0.6 (Comparative Examples 1 to 3), the capacity retention rate of the resulting batteries 500 after 400 cycles is significantly reduced.

[0263] As shown in Table 3, when the Ia / Ib ratio of the negative electrode active particles 100 is between 0.6 and 0.95, the thickness expansion rate of the battery 500 using the negative electrode active particles 100 (i.e., the battery 500 prepared from the negative electrode active particles 100 of Examples 1 to 5) after 400 cycles is less than or equal to 5.4%. Furthermore, as the Ia / Ib ratio increases, the thickness expansion rate of the battery 500 using the negative electrode active particles 100 gradually decreases after 400 cycles. When the Ia / Ib ratio of the negative electrode active particles 100 is less than 0.6 (Comparative Examples 1 to 3), the thickness expansion rate of the resulting battery 500 after 400 cycles is significantly increased.

[0264] As shown in Table 3, when the Ic / Id ratio of the negative electrode active particles 100 is between 0.5 and 0.95, the batteries 500 using the negative electrode active particles 100 (i.e., the batteries 500 prepared from the negative electrode active particles 100 of Examples 1 to 5) all have a high cycle capacity retention rate after 400 cycles, and the cycle capacity retention rate is all above 92.2%. Moreover, as the Ic / Id ratio increases, the 400-cycle capacity retention rate of the batteries 500 using the negative electrode active particles 100 gradually increases. When the Ic / Id ratio of the negative electrode active particles 100 is less than 0.5 (Comparative Examples 1 to 3), the capacity retention rate of the resulting batteries 500 after 400 cycles is significantly reduced.

[0265] As shown in Table 3, when the Ic / Id ratio of the negative electrode active particles 100 is between 0.5 and 0.95, the thickness expansion rate of the battery 500 using the negative electrode active particles 100 (i.e., the battery 500 prepared from the negative electrode active particles 100 of Examples 1 to 5) after 400 cycles is less than or equal to 5.4%. As the Ic / Id ratio increases, the thickness expansion rate of the battery 500 using the negative electrode active particles 100 gradually decreases after 400 cycles. When the Ic / Id ratio of the negative electrode active particles 100 is less than 0.5 (Comparative Examples 1 to 3), the thickness expansion rate of the resulting battery 500 after 400 cycles is significantly increased.

[0266] 12 and 13 , an embodiment of the present application further provides an electronic device 600 , which includes a device body 610 and the battery 500 described in the embodiment of the present application, wherein the battery 500 is used to power the device body 610 .

[0267] The electronic device 600 of the embodiment of the present application can be, but is not limited to, a portable electronic device 600 such as a mobile phone, a tablet computer, a laptop computer, a desktop computer, a smart toy, smart glasses, a smart bracelet, a smart watch, an e-reader, a game console, or a toy.

[0268] For a detailed description of the battery 500 , please refer to the description of the corresponding part of the above embodiment, which will not be repeated here.

[0269] It can be understood that the electronic device 600 described in this embodiment is merely a form of electronic device 600 used by the battery 500, and should not be understood as a limitation on the electronic device 600 provided in this application, nor should it be understood as a limitation on the battery 500 provided in each embodiment of this application.

[0270] Optionally, the device body 610 of the embodiment of the present application further includes a display screen 611, a middle frame 613, and a housing 615. The housing 615 is disposed opposite the display screen 611, the middle frame 613 is located between the display screen 611 and the housing 615, and the sidewalls of the middle frame 613 are exposed to the display screen 611 and the housing 615. The middle frame 613 and the housing 615 enclose an accommodating space, which is used to accommodate the battery 500. The display screen 611 is electrically connected to the battery 500, and the battery 500 provides power for the display screen 611.

[0271] Optionally, the display screen 611 may be, but is not limited to, one or more of a liquid crystal display screen, a light emitting diode display screen (LED display screen), a micro light emitting diode display screen (Micro LED display screen), a sub-millimeter light emitting diode display screen (Mini LED display screen), an organic light emitting diode display screen (OLED display screen), etc.

[0272] Please also refer to Figure 14. Optionally, the device body 610 of the present application further includes a processor 617 and a memory 616. The processor 617 and the memory 616 are disposed in the accommodation space. The processor 617 is electrically connected to the battery 500, the display screen 611, and the memory 616, respectively. The processor 617 is configured to control the display screen 611 for display, and the memory 616 is configured to store program codes required for the processor 617 to operate, program codes required to control the display screen 611, and display content of the display screen 611.

[0273] Optionally, the processor 617 includes one or more general-purpose processors, where a general-purpose processor can be any type of device capable of processing electronic instructions, including a central processing unit (CPU), a microprocessor, a microcontroller, a main processor, a controller, and an ASIC. The processor 617 is used to execute various types of digital storage instructions, such as software or firmware programs stored in the memory 616, which enables the computing device to provide a wide variety of services.

[0274] Optionally, the memory 616 may include volatile memory, such as random access memory (RAM); the memory 616 may also include non-volatile memory (NVM), such as read-only memory (ROM), flash memory (FM), hard disk drive (HDD), or solid-state drive (SSD). The memory 616 may also include a combination of the above types of memory 616.

[0275] In some embodiments, the device body 610 of the present embodiment further includes a camera module 618, which is disposed in the accommodation space. The camera module 618 is electrically connected to the processor 617 and the battery 500, respectively, for taking pictures under the control of the processor 617. The battery 500 also provides power to the camera module 618.

[0276] Optionally, the housing 615 has a light-transmitting portion 6151, through which the camera module 618 can capture images. That is, the camera module 618 in this embodiment is a rear-facing camera module 618. It is understood that in other embodiments, the light-transmitting portion 6151 may be disposed on the display screen 611, that is, the camera module 618 is a front-facing camera module 618. In the schematic diagram of this embodiment, the light-transmitting portion 6151 is illustrated as an opening. In other embodiments, the light-transmitting portion 6151 may not be an opening, but may be made of a light-transmitting material, such as plastic or glass.

[0277] Mentioning "embodiments" and "implementation methods" in this application means that the specific features, structures or characteristics described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrases in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described in this application can be combined with other embodiments. In addition, it should be understood that the features, structures or characteristics described in the various embodiments of the present application can be arbitrarily combined to form another embodiment that does not deviate from the spirit and scope of the technical solution of the present application, unless there is a contradiction between them.

[0278] Finally, it should be noted that the above implementation modes are only used to illustrate the technical solutions of the present application and are not limiting. Although the present application has been described in detail with reference to the above preferred implementation modes, ordinary technicians in this field should understand that the technical solutions of the present application can be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present application.

Claims

1. A negative electrode active particle, characterized in that: include: a skeleton having a plurality of pores; and Silicon particles, wherein the silicon particles are located in the plurality of pores, and there is a gap between the silicon particles and the inner wall of the pores, and the width of the gap ranges from 0.4 nm to 1 nm; The negative electrode active particles have a first X-ray diffraction pattern, in which the gaps and the silicon particles satisfy the relationship 0.6≤Ia / Ib≤0.95, wherein Ia is the minimum value of the diffraction intensity in the range of 8.8° to 22° when 2θ is in the first X-ray diffraction pattern; Ib is the intensity of the diffraction peak of Si(111) in the range of 2θ being 28.2° to 28.5° when 2θ is in the first X-ray diffraction pattern; and 2θ is the diffraction angle.

2. The negative electrode active particle according to claim 1, characterized in that In the first X-ray diffraction pattern, the gaps and the silicon particles satisfy the relationship 0.6≤Ia / Ib≤0.

85.

3. The negative electrode active particle according to claim 1, characterized in that The average pore size of the pores ranges from 0.8 nm to 4 nm.

4. The negative electrode active particle according to claim 1, characterized in that The pore volume V of the skeleton 10 ranges from 0.2 cm 3 / g to 1.5 cm 3 / g.

5. The negative electrode active particle according to claim 1, characterized in that The negative electrode active particles have a second X-ray diffraction pattern after heat treatment. In the second X-ray diffraction pattern, the gap and the silicon particles satisfy the relationship: 0.5≤Ic / Id≤0.95, wherein Ic is the minimum value of the diffraction intensity in the range of 8.8° to 22° when 2θ is in the second X-ray diffraction pattern; Id is the intensity of the diffraction peak of Si(111) with 2θ being 28.2° to 28.5° in the second X-ray diffraction pattern; wherein the heat treatment includes heating to 700°C in an inert atmosphere, keeping the temperature for 2 hours, and cooling to room temperature.

6. The negative electrode active particle according to claim 5, characterized in that In the second X-ray diffraction pattern, the gap and the silicon particles satisfy the relationship: 0.5≤Ic / Id≤0.

85.

7. The negative electrode active particle according to claim 1, characterized in that The negative electrode active particles further include a carbon coating layer, which is wrapped around the outer periphery of the skeleton.

8. The negative electrode active particle according to claim 7, characterized in that: The thickness of the carbon coating layer ranges from 1 nm to 1000 nm.

9. The negative electrode active particle according to claim 7, characterized in that: In the negative electrode active particles, the total mass fraction of silicon and carbon is greater than or equal to 90%, and the mass ratio of silicon to carbon is in the range of 1:99 to 95:

5.

10. The negative electrode active particle according to claim 7, characterized in that: The skeleton is a porous carbide, and the porous carbide includes at least one element selected from nitrogen, oxygen, fluorine, chlorine, titanium, zirconium, vanadium, molybdenum, tungsten, aluminum, and iron; in the negative electrode active particles, the mass fraction of silicon element ranges from 1% to 95%, and the total mass fraction of the porous carbide and the carbon coating layer ranges from 5% to 99%.

11. The negative electrode active particle according to claim 7, characterized in that: The median particle size D50 of the negative electrode active particles is in the range of 300 nm ≤ D50 ≤ 50 μm, the average particle size D1 of the silicon particles is in the range of 0.4 nm ≤ D1 ≤ 2 nm; the specific surface area S of the negative electrode active particles is in the range of 0.1 m 2 / g≤S≤30m 2 / g.

12. The negative electrode active particle according to claim 1, characterized in that: The negative electrode active particles further include a doping element, and the doping element includes at least one of a non-metallic element or a metallic element.

13. The negative electrode active particle according to claim 1, characterized in that: The specific capacity of the negative electrode active particles ranges from 1700 mAh / g to 2000 mAh / g.

14. The negative electrode active particle according to claim 1, characterized in that: The capacity retention rate of the negative electrode active particles after 50 cycles is greater than or equal to 95%.

15. A method for preparing negative electrode active particles, characterized in that: include: providing a framework having a plurality of pores; and A silicon source gas is introduced into the skeleton to deposit silicon particles in the multiple pores to obtain negative electrode active particles, wherein there is a gap between the silicon particles and the inner wall of the pore, and the gap ranges from 0.4 nm to 1 nm; the negative electrode active particles have a first X-ray diffraction pattern, and the gap and the silicon particles satisfy the relationship 0.6≤Ia / Ib≤0.95, wherein Ia is the minimum value of the diffraction intensity in the range of 8.8° to 22° when 2θ is in the first X-ray diffraction pattern; Ib is the intensity of the diffraction peak of Si(111) in the first X-ray diffraction pattern when 2θ is 28.2° to 28.5°.

16. The method for preparing negative electrode active particles according to claim 15, characterized in that: The step of introducing a silicon source gas into the skeleton to deposit silicon particles in the plurality of pores to obtain negative electrode active particles comprises: At a temperature T1 of 400°C ≤ T1 ≤ 700°C, silicon source gas is introduced to deposit silicon particles in the plurality of pores, and the ratio t / V of the deposition time t of the silicon particles to the pore volume V of the skeleton is controlled to be in the range of 10 gh / cm 3 ≤t / V≤500gh / cm 3 .

17. The method for preparing negative electrode active particles according to claim 15 or 16, characterized in that: The ratio m / V' of the mass m of the silicon source gas to the total volume V' of the plurality of pores of the skeleton is in the range of 0.05 g / cm 3 ≤m / V'≤1.8g / cm 3 .

18. A negative electrode plate, characterized in that: include: negative electrode current collector; as well as A negative electrode active layer is provided on the surface of the negative electrode current collector, and the negative electrode active layer comprises the negative electrode active particles according to any one of claims 1 to 14 or the negative electrode active particles prepared by the method for preparing the negative electrode active particles according to any one of claims 15 to 17.

19. A battery, characterized in that: include: electrolyte; a positive electrode sheet, wherein the positive electrode sheet is at least partially immersed in the electrolyte; a diaphragm, the diaphragm being located on one side of the positive electrode plate and at least partially immersed in the electrolyte, and The negative electrode plate according to claim 18 is arranged on a side of the diaphragm away from the positive electrode plate and is at least partially immersed in the electrolyte.

20. An electronic device, characterized in that: include: Equipment body; as well as The battery according to claim 19 is used to power the device body.

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