Negative electrode sheet, battery, and electric device

Abstract

This invention provides a negative electrode sheet, a battery, and an electrical device. The negative electrode sheet includes a negative electrode active layer, the negative electrode active layer includes a negative electrode active material, and the true density ρ of He gas in the negative electrode active material is... He For ρ S -0.15g / cm 3 ~ρ S g / cm 3 True density of electrolyte ρ E For ρ S -0.8g / cm 3 ~ρ S -0.6g / cm 3 , where ρ S The skeletal density of the negative electrode active material is given in g / cm³. 3 The negative electrode sheet provided by this invention limits the relationship between the true density of He gas in the negative electrode active material, the true density of the electrolyte, and the skeleton density, that is, limits the skeleton structure and pore structure of the negative electrode active material. By increasing the closed pores that the electrolyte cannot wet, the theoretical capacity of the negative electrode active material is increased, thereby increasing the energy density of the battery. By increasing the open pore channels of the negative electrode active material, the kinetic performance of the battery is improved.

Description

Technical Field

[0001] This invention belongs to the field of battery technology, and particularly relates to a negative electrode sheet, a battery, and an electrical device. Background Technology

[0002] Rechargeable batteries, also known as secondary batteries, are energy storage devices capable of undergoing multiple charge-discharge cycles through electrochemical reactions. With the increasing global demand for renewable energy, portable electronic devices, and electric vehicles, rechargeable batteries have attracted considerable attention. However, existing battery technologies still face challenges in terms of energy density and kinetic performance. Summary of the Invention

[0003] The main objective of this invention is to provide a negative electrode sheet that can improve the energy density and dynamic performance of a battery.

[0004] The present invention also provides a battery comprising the above-mentioned negative electrode, thereby the battery having high energy density and excellent kinetic performance.

[0005] The present invention also provides an electrical device including the above-mentioned battery, therefore, the battery of the electrical device has superior performance.

[0006] In a first aspect, the present invention provides a negative electrode sheet comprising a negative electrode active layer, wherein the negative electrode active layer comprises a negative electrode active material, and the He gas true density ρ of the negative electrode active material is... He For ρ S -0.15g / cm 3 ~ρ S g / cm 3 True density of electrolyte ρ E For ρ S -0.8g / cm 3 ~ρ S -0.6g / cm 3 , where ρ S The skeletal density of the negative electrode active material is given in g / cm³. 3 .

[0007] As described above, the skeletal density ρ of the negative electrode active material is... S =0.03462 / (d 002 ×d 100 ^2), wherein the interlayer spacing d of the negative electrode active material 002 The interlayer spacing d of the negative electrode active material is 0.36 nm to 0.40 nm. 100 The wavelength range is 0.2059nm to 0.2070nm.

[0008] As described above, the negative electrode active material satisfies (1-ρ) E / ρHe ) / (1-ρ E / ρ S )≥0.87.

[0009] As described above, the interlayer spacing d of the negative electrode active material... 002 The wavelength ranges from 0.375nm to 0.390nm.

[0010] As described above, the interlayer spacing d of the negative electrode active material... 002 The wavelength range is 0.380nm to 0.390nm.

[0011] As described above, the true density ρ of He gas in the negative electrode active material is... He For ρ S -0.1g / cm 3 ~ρ S g / cm 3 .

[0012] As described above, the true density ρ of the electrolyte of the negative electrode active material is... E For ρ S -0.8g / cm 3 ~ρ S -0.75g / cm 3 .

[0013] As described above, the negative electrode active material satisfies (1-ρ) E / ρ He ) / (1-ρ E / ρ S )≥0.91.

[0014] As described above, the negative electrode active material includes hard carbon and / or soft carbon.

[0015] In a second aspect, the present invention provides a battery comprising the negative electrode sheet as described above.

[0016] Thirdly, the present invention provides an electrical device including the battery described above.

[0017] The negative electrode sheet provided by this invention limits the relationship between the true density of He gas in the negative electrode active material, the true density of the electrolyte, and the skeleton density, that is, limits the skeleton structure and pore structure of the negative electrode active material. By increasing the closed pores that the electrolyte cannot wet, the theoretical capacity of the negative electrode active material is increased, thereby increasing the energy density of the battery. By increasing the open pore channels of the negative electrode active material, the dynamic performance of the battery is improved. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0019] Against the backdrop of the current urgent global demand for renewable energy and efficient energy storage systems, sodium-ion batteries, as an emerging energy storage technology, have attracted widespread attention due to their cost advantages and abundant resources. Compared with lithium-ion batteries, sodium-ion batteries have significant advantages in raw material cost and resource availability. However, sodium-ion batteries still face challenges in energy density and kinetic performance, limiting their widespread adoption in high-performance applications. Therefore, developing anode materials with high energy density and excellent kinetic performance has become a key research focus.

[0020] Commonly used anode materials include graphite, artificial graphite, hard carbon, soft carbon, silicon-based materials, and lithium titanate. Among them, hard carbon has become an ideal anode active material for sodium-ion batteries due to its unique structural characteristics. Its abundant microporous structure provides a large number of sodium storage sites, while its good structural stability and long cycle life make it perform excellently in long-term use. The sodium storage mechanisms of hard carbon mainly include surface adsorption sodium storage, interlayer sodium intercalation, and microporous sodium storage. The effective functioning of these mechanisms depends on the surface properties, microcrystalline structure, and pore structure of the material. Therefore, a deep understanding and optimization of the structural characteristics of hard carbon is crucial for improving its electrochemical performance.

[0021] Currently, the characterization of pore structure mainly relies on nitrogen (N2) or carbon dioxide (CO2) adsorption tests. These methods are mainly for detecting surface micropores and are difficult to effectively describe the closed-pore characteristics in hard carbon, thus restricting the optimal design of materials.

[0022] The inventors of this application have discovered through research that by defining the relationship between the true density of He gas and the true density of electrolyte and the framework density of hard carbon, the crystallographic parameters, closed-pore volume and pore channel characteristics of hard carbon can be accurately evaluated, thereby enabling the development of batteries with high capacity and high kinetic performance.

[0023] Based on this, in a first aspect, the present invention provides a negative electrode sheet, comprising a negative electrode active layer, the negative electrode active layer comprising a negative electrode active material, and the He gas true density ρ of the negative electrode active material. He For ρ S -0.15g / cm 3 ~ρ S g / cm 3 True density of electrolyte ρ E For ρ S-0.8g / cm 3 ~ρ S -0.6g / cm 3 , where ρ S The skeleton density of the negative electrode active material, g / cm³ 3 .

[0024] For example, the true density ρ of He gas He It can be ρ S -0.15g / cm 3 ρ S -0.13g / cm 3 ρ S -0.1g / cm 3 ρ S -0.08g / cm 3 ρ S -0.05g / cm 3 ρ S -0.03g / cm 3 ρ S -0.01g / cm 3 ρ S g / cm 3 Or a range consisting of any two of them. Electrolyte true density ρ E It can be ρ S -0.8g / cm 3 ρ S -0.77g / cm 3 ρ S -0.75g / cm 3 ρ S -0.73g / cm 3 ρ S -0.7g / cm 3 ρ S -0.65g / cm 3 ρ S -0.6g / cm 3 or a range consisting of any two of them.

[0025] It is understandable that the framework density of the negative electrode active material represents the density of the solid portion of the negative electrode active material, excluding the volume of any open or closed pores. The true density of helium gas can characterize the closed pores that have not been penetrated by helium gas. The true density of the electrolyte can characterize the closed pores that have not been wetted by the electrolyte.

[0026] This invention improves the energy density and kinetic performance of the battery by defining the relationship between the true density of He gas in the negative electrode active material, the true density of the electrolyte, and the skeleton density. This is because the true density of He gas ρ HeThis often reflects the pore structure of the negative electrode active material. Since the molecular dynamic diameter of He gas is approximately 0.26 nm, it can detect even small pores. If ρ He The closer the value is to the skeleton density of the negative electrode active material, the fewer closed pores and the more interconnected open channels exist in the material. These open channels can accelerate the solid-phase diffusion of ions within the negative electrode active material, thereby improving the battery's kinetic performance, specifically manifested in rate discharge performance and sodium deposition rate. Electrolyte true density ρ E The true density of the electrolyte represents the closed pores that are not wetted by the electrolyte, and these closed pores are often active sodium storage sites. The lower the true density of the electrolyte, the more closed pores are not wetted by the electrolyte, and the more active sodium storage sites there are, which can improve the capacity of the negative electrode active material and increase the energy density of the battery. However, an excessively low true density of the electrolyte can also lead to a decrease in the compaction density of the negative electrode active material, which in turn affects the energy density of the battery.

[0027] Therefore, this invention limits the relationship between the true density of He gas in the negative electrode active material, the true density of the electrolyte, and the skeleton density, that is, limits the skeleton structure and pore structure of the negative electrode active material. By increasing the closed pores that the electrolyte cannot wet, the theoretical capacity of the negative electrode active material is increased, thereby increasing the energy density of the battery. By increasing the open pore channels of the negative electrode active material, the dynamic performance of the battery is improved.

[0028] In some embodiments of the present invention, the skeleton density ρ of the negative electrode active material S =0.03462 / (d 002 ×d 100 ^2), where the interlayer spacing d of the negative electrode active material 002 The interlayer spacing d of the negative electrode active material is 0.36 nm to 0.40 nm, for example, it can be a range of 0.36 nm, 0.37 nm, 0.38 nm, 0.39 nm, 0.40 nm or any combination thereof. 100 The range is 0.2059nm to 0.2070nm, for example, it can be a range of 0.2059nm, 0.206nm, 0.2062nm, 0.2065nm, 0.2068nm, 0.207nm or any combination thereof.

[0029] Because the sodium intercalation process of the negative electrode active material involves interlayer sodium intercalation, the interlayer spacing d 002 A larger interlayer spacing d of the negative electrode active material facilitates ion insertion and extraction, increases ion diffusion rate, and thus allows the negative electrode active material to achieve its full capacity, thereby improving the battery's energy density. Furthermore, the interlayer spacing d of the negative electrode active material... 002The larger the interlayer spacing, the smaller the diffusion barrier of ions between layers, which is beneficial for improving rate performance. However, at the same time, a large interlayer spacing will lead to a lower skeleton density of the negative electrode active material and a lower compaction density of the negative electrode sheet. Therefore, the interlayer spacing of the negative electrode active material should be within a reasonable range.

[0030] d 100 This reflects the lateral dimensions of the negative electrode active material, with a smaller d... 100 This indicates that the low degree of graphitization of the negative electrode active material is beneficial for providing more active sites and a higher specific surface area, thereby improving the capacity of the negative electrode active material and increasing the energy density of the battery.

[0031] In some embodiments of the present invention, the negative electrode active material satisfies (1-ρ) E / ρ He ) / (1-ρ E / ρ S )≥0.87, for example, it can be a range consisting of 0.87, 0.88, 0.89, 0.9, 0.91, 0.92, 0.93, 0.94, 0.95 or any two of them.

[0032] In this invention (1-ρ E / ρ He ) / (1-ρ E / ρ S A value ≥ 0.87 can improve the dynamic performance of the battery.

[0033] I can understand, 1 / ρ He -1 / ρ S This represents the volume of a closed porous structure that helium cannot penetrate. This portion can serve as a sodium storage site, but due to its complete enclosure, sodium diffusion is difficult and the kinetics are poor. 1 / ρ E -1 / ρ S This represents the volume of the pores not wetted by the electrolyte, and is also an active sodium storage site. 1 / ρ E -1 / ρ S With 1 / ρ He -1 / ρ S The difference can be considered as a sodium storage site with high kinetic performance. This difference is related to the volume of the pore not wetted by the electrolyte, i.e., 1 / ρ E -1 / ρ S The ratio of ρ to ρ can represent the kinetic capability of the negative electrode active material, and its formula is (1-ρ) / ρ = 1 / 2. E / ρ He ) / (1-ρ E / ρ S The larger the value, the better the battery's dynamic performance.

[0034] In some embodiments of the present invention, the interlayer spacing d of the negative electrode active material002 The wavelength range is 0.375 nm to 0.390 nm, for example, it can be a range of 0.375 nm, 0.377 nm, 0.380 nm, 0.382 nm, 0.385 nm, 0.387 nm, 0.390 nm, or any combination thereof. Further, the interlayer spacing d of the negative electrode active material... 002 The wavelength range is 0.380nm to 0.390nm.

[0035] As a preferred option, this approach can further enhance the capacity utilization of the negative electrode active material, thereby increasing the energy density of the battery and improving rate performance.

[0036] In some embodiments of the present invention, the He gas true density ρ of the negative electrode active material is... He For ρ S -0.1g / cm 3 ~ρ S g / cm 3 For example, it can be ρ S -0.1g / cm 3 ρ S -0.08g / cm 3 ρ S -0.05g / cm 3 ρ S -0.03g / cm 3 ρ S -0.01g / cm 3 ρ S g / cm 3 or a range consisting of any two of them.

[0037] As a preferred approach, the closed pores can be further reduced, the open channels can be increased, and the solid-phase diffusion of ions within the negative electrode active material can be accelerated, thereby improving the kinetic performance of the battery.

[0038] In some embodiments of the present invention, the true density ρ of the electrolyte of the negative electrode active material is... E For ρ S -0.8g / cm 3 ~ρ S -0.75g / cm 3 For example, it can be ρ S -0.8g / cm 3 ρ S -0.79g / cm 3 ρ S -0.78g / cm 3 ρ S -0.77g / cm 3 ρ S -0.76g / cm3 ρ S -0.75g / cm 3 or a range consisting of any two of them.

[0039] As a preferred option, the number of closed pores not wetted by the electrolyte can be further increased, resulting in more active sodium storage sites, which can further improve the capacity of the negative electrode active material and increase the energy density of the battery.

[0040] In some embodiments of the present invention, the negative electrode active material satisfies (1-ρ) E / ρ He ) / (1-ρ E / ρ S )≥0.91, for example, it can be a range consisting of 0.91, 0.92, 0.93, 0.94, 0.95 or any two of them.

[0041] As a preferred option, the kinetic performance of the battery can be further improved.

[0042] The various parameters of the aforementioned negative polarity active material can be tested by sampling the negative polarity active material from the negative polarity slurry before coating, or by sampling the negative polarity active layer after rolling. The test results from both methods may differ, but within the error range, they are considered to be essentially consistent.

[0043] In some embodiments of the present invention, the negative electrode active material includes hard carbon and / or soft carbon.

[0044] The negative electrode active material in this invention includes hard carbon and / or soft carbon, which can effectively improve the energy density and kinetic performance of the battery.

[0045] The negative electrode sheet of the present invention also includes a negative electrode current collector, and the negative electrode active layer can be disposed on one or both surfaces of the negative electrode current collector.

[0046] Secondly, the present invention provides a battery comprising the negative electrode sheet as described above, which has advantages corresponding to the aforementioned negative electrode sheet, and will not be elaborated further.

[0047] The battery in this invention can be a sodium-ion battery, a lithium-ion battery, or a potassium-ion battery.

[0048] The battery of the present invention, in addition to the negative electrode, also includes a separator, a positive electrode, and an electrolyte. The separator can be a separator conventionally used in the art, and can be at least one of polyethylene, polypropylene, and polyvinylidene fluoride. The electrolyte can include ether-based electrolytes and / or ester-based electrolytes, and there are no particular limitations on electrolyte additives.

[0049] The positive electrode sheet of this invention includes a positive electrode active layer and a positive electrode current collector. The positive electrode active layer can be disposed on one or both surfaces of the positive electrode current collector. The positive electrode active layer includes a positive electrode active material, which may include at least one of transition metal oxides, polyanionic compounds, organic polymers, and Prussian blue-based materials.

[0050] This invention does not impose any special restrictions on the conductive agents, binders, and dispersants used in the battery.

[0051] The battery of the present invention can be prepared using conventional methods in the art. Specifically, the positive electrode, separator and negative electrode can be stacked in sequence, and the cell can be obtained by stacking or winding. Then, the battery can be obtained by baking, liquid injection, formation and packaging.

[0052] The battery of the present invention can be a single cell, a battery pack, a battery stack, or a cylindrical cell formed by connecting single cells. These cells can be electrically connected by conventional methods in the art, such as series connection, parallel connection, or a hybrid connection including these connection methods, etc., without particular limitation.

[0053] Thirdly, the present invention provides an electrical device including the battery as described above, which has advantages corresponding to the negative electrode plate described above, and will not be elaborated further.

[0054] The electrical equipment of the present invention can be conventional electrical equipment in the art, such as power equipment (e.g., electric vehicles), electronic equipment (e.g., computers, mobile phones, digital cameras, printers, fax machines, etc.), wearable devices (e.g., watches, wristbands, VR glasses, etc.), and home appliances (e.g., air conditioners, refrigerators, washing machines, microwave ovens, etc.), etc., and there are no particular limitations.

[0055] The technical solution of the present invention will be further described below with reference to specific embodiments.

[0056] Example 1

[0057] The method for preparing the negative electrode sheet in this embodiment includes the following steps:

[0058] By controlling process parameters such as hard carbon precursor materials, carbonization conditions, particle size, and specific surface area, negative electrode active materials with different microcrystalline structures and pore structures were obtained. The interlayer spacing d of the hard carbon materials was then measured. 002 It is 0.3753nm, d 100 The true density ρ of He gas is 0.2069 nm. He It is 2.037 g / cm³. 3 True density of electrolyte ρ E It is 1.366 g / cm³ 3 The skeleton density ρ was calculated. S =0.03462 / (d002 ×d 100 ^2)=2.1550g / cm 3 , ρ S -ρ He It is 0.118 g / cm³ 3 , ρ S -ρ E It is 0.789 g / cm³ 3 , (1-ρ E / ρ He ) / (1-ρ E / ρ S The value is 0.899.

[0059] The above-mentioned negative electrode active material hard carbon, conductive agent carbon black (CB), thickener carboxymethyl cellulose (CMC), and binder styrene-butadiene rubber (SBR) are mixed evenly with deionized water at a mass ratio of 95:1:2:2 to form a negative electrode slurry. The negative electrode slurry is then coated onto the two surfaces of an aluminum foil using a coating machine to obtain a negative electrode sheet.

[0060] Example 2-13

[0061] The preparation methods of the negative electrode sheets in Examples 2-13 are basically the same as those in Example 1, except that the d of the hard carbon, a negative electrode active material, is changed. 002 d 100 ρ He ρ E ρ S ρ S -ρ He ρ S -ρ E 、(1-ρ E / ρ He ) / (1-ρ E / ρ S One or more of the following.

[0062] Comparative Example 1

[0063] The preparation method of the negative electrode sheet in Comparative Example 1 is basically the same as that in Example 1, except that ρ S -ρ He It is 0.187 g / cm³ 3 .

[0064] Comparative Example 2

[0065] The preparation method of the negative electrode sheet in Comparative Example 2 is basically the same as that in Example 1, except that ρ S -ρ He It is 0.308 g / cm 3 .

[0066] Comparative Example 3

[0067] The preparation method of the negative electrode sheet in Comparative Example 3 is basically the same as that in Example 1, except that ρ S -ρ E It is 0.498 g / cm³ 3 .

[0068] Comparative Example 4

[0069] The preparation method of the negative electrode sheet in Comparative Example 4 is basically the same as that in Example 1, except that ρ S -ρ E It is 0.882 g / cm 3 .

[0070] Comparative Example 5

[0071] The preparation method of the negative electrode sheet in Comparative Example 5 is basically the same as that in Example 1, except that ρ S -ρ He It is 0.173 g / cm³ 3 , ρ S -ρ E It is 0.839 g / cm³ 3 .

[0072] Comparative Example 6

[0073] The preparation method of the negative electrode sheet in Comparative Example 6 is basically the same as that in Example 1, except that ρ S -ρ He 0.200 g / cm 3 , ρ S -ρ E It is 0.557 g / cm³ 3 .

[0074] Experimental example:

[0075] The positive electrode active material sodium iron pyrophosphate (NFPP), conductive agent carbon nanotubes (CNTs), binder polyvinylidene fluoride (PVDF) are mixed with N-methylpyrrolidone (NMP) in a mass ratio of 96:2:2. The mixture is prepared into a positive electrode slurry using a homogenizing device and then uniformly coated on both surfaces of an aluminum foil to obtain a positive electrode sheet.

[0076] 1M NaPF6 was mixed with ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) in a volume ratio of 1:1:1 to prepare a base solution. Then, 5% (by mass) of fluoroethylene carbonate (FEC) was added to prepare an electrolyte.

[0077] 1, d 002 and d 100Testing: First, samples of the battery's negative electrode were taken by scraping. The scraped samples were soaked in water, sonicated for 30 minutes, and then centrifuged to remove the conductive agent and binder, leaving the active material. This process was repeated at least three times to ensure complete removal of the auxiliary materials. The dried residue is the negative electrode active material. The negative electrode active material was then subjected to XRD testing. 002 and d 100 The test method can refer to the interlayer spacing d in GB / T 24533-2019 "Graphite Anode Materials for Lithium-ion Batteries". 002 and d 100 The testing method and the testing instrument were X-ray diffractometers.

[0078] 2. True density of He gas ρ He Test: Same as d 002 and d 100 The test method involves collecting negative electrode active materials for true density testing. A true density meter is used, with He gas as the test gas, and the test is conducted according to the method specified in GB24533-2009 "Graphite Anode Materials for Lithium-ion Batteries".

[0079] 3. True density of electrolyte ρ E Test: Same as d 002 and d 100 The test method involves collecting negative electrode active materials for true density testing. A specific gravity bottle is used, and an electrolyte (which can be a mixture of esters and ethers, or just one of the electrolyte components) is used as the test liquid. The test is conducted based on the method specified in GB / T217-2008 "Determination of True Density of Coal".

[0080] 4. Compacted density test: Select 5 different positions of the negative electrode sheet after rolling and use a thickness measuring instrument to measure the thickness, subtract the foil thickness, take the average value D, and then calculate the compacted density based on the surface density. Compacted density = surface density / D.

[0081] 5. Specific capacity test: Using a glass fiber separator, the negative electrode and metallic sodium are assembled into a coin cell. After standing in a constant temperature environment of 25℃ for 12 hours, it is discharged to 0V at 0.05C. After standing for 10 minutes, it is charged to 2.5V at 0.05C. The charging specific capacity is the specific capacity of the negative electrode.

[0082] 6. Sodium Deposition Rate Test: A 1Ah stacked battery is constructed by sequentially stacking the negative electrode, polypropylene separator, and positive electrode in that order, injecting electrolyte, and then sealing. After completing aging, formation, and capacity testing processes, the battery is charged at a constant current of xC until the upper limit of the cutoff voltage, then charged at a constant voltage until the current reaches 0.05C. After standing for 5 minutes, the battery is disassembled to observe the sodium deposition at the interface. If no sodium deposition occurs on the surface of the negative electrode, the charging rate is increased and the test is repeated until sodium deposition occurs on the surface of the negative electrode. The maximum charging rate x at which no sodium deposition occurs on the surface of the negative electrode is recorded to characterize the battery's kinetic performance.

[0083] 7. Rate Discharge Test: A 1Ah stacked battery is assembled by sequentially stacking the negative electrode, polypropylene separator, and positive electrode in that order, injecting electrolyte, and then sealing. After completing the aging, formation, and capacity testing processes, the battery is charged at a constant current of 0.33C to the charging cutoff voltage and then discharged at a constant current of 0.33C to the discharging cutoff voltage, recording the discharge capacity C1; subsequently, the battery is charged at a constant current of 0.33C to the charging cutoff voltage and then discharged at a constant current of 7C to the discharging cutoff voltage, recording the discharge capacity C2. The rate charging performance is characterized as C2 / C1.

[0084] 8. Energy Density: A 1Ah stacked battery is constructed by sequentially stacking the negative electrode, polypropylene separator, and positive electrode in that order, injecting electrolyte, and then sealing. After completing the aging, formation, and capacity testing processes, the battery is charged to 3.75V at 25℃ with a constant current of 0.2C, then charged with a constant voltage until the current drops to 0.02C. After standing for 5 minutes, the battery is discharged to 2.0V with a constant current of 0.2C. The initial discharge capacity Q_discharge and the initial discharge energy E_discharge are recorded. The mass of the battery is weighed and recorded as W. The mass energy density ED = E_discharge / W is calculated.

[0085] Table 1

[0086]

[0087] As shown in Table 1, compared with the comparative example, the present invention limits the relationship between the true density of He gas in the negative electrode active material and the true density of the electrolyte and the skeleton density, that is, limits the skeleton structure and pore structure of the negative electrode active material. By increasing the closed pores that the electrolyte cannot wet, the theoretical capacity of the negative electrode active material is increased, thereby increasing the energy density of the battery. By increasing the open pore channels of the negative electrode active material, the dynamic performance of the battery is improved.

[0088] Compared with Examples 2-7, 9, 11, and 13, the ρ of Examples 1, 8, 10, and 12 is different. S -ρ E At 0.75 g / cm 3 ~0.8g / cm 3Therefore, its energy density is relatively high.

[0089] Compared with Examples 1, 3, 8, 9, 11, and 13, Examples 2, 4, 6, 7, 10, and 12 have (1-ρ) E / ρ He ) / (1-ρ E / ρ S )≥0.91 and ρ S -ρ He At 0g / cm 3 ~0.1g / cm 3 Therefore, its dynamic performance is superior, that is, its rate discharge and absorption rate performance are superior.

[0090] Finally, it should be noted that other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This invention is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein, and is not limited to the precise structures described above, and various modifications and changes can be made without departing from its scope. The scope of the invention is limited only by the appended claims.

Claims

1. A negative electrode sheet, characterized in that, The negative electrode active layer includes a negative electrode active material, and the true density ρ of He gas in the negative electrode active material is... He For ρ S -0.15g / cm 3 ~ρ S g / cm 3 True density of electrolyte ρ E For ρ S -0.8g / cm 3 ~ρ S -0.6g / cm 3 , where ρ S The skeletal density of the negative electrode active material is given in g / cm³. 3 .

2. The negative electrode sheet according to claim 1, characterized in that, The skeleton density ρ of the negative electrode active material S =0.03462 / (d 002 ×d 100 ^2), wherein the interlayer spacing d of the negative electrode active material 002 The interlayer spacing d of the negative electrode active material is 0.36 nm to 0.40 nm. 100 The wavelength range is 0.2059nm to 0.2070nm.

3. The negative electrode sheet according to claim 1 or 2, characterized in that, The negative electrode active material satisfies (1-ρ) E / ρ He ) / (1-ρ E / ρ S )≥0.

87.

4. The negative electrode sheet according to claim 2, characterized in that, The interlayer spacing d of the negative electrode active material 002 The wavelength ranges from 0.375nm to 0.390nm.

5. The negative electrode sheet according to claim 2 or 4, characterized in that, The interlayer spacing d of the negative electrode active material 002 The wavelength range is 0.380nm to 0.390nm.

6. The negative electrode sheet according to any one of claims 1-5, characterized in that, The true density ρ of He gas in the negative electrode active material He For ρ S -0.1g / cm 3 ~ρ S g / cm 3 .

7. The negative electrode sheet according to any one of claims 1-6, characterized in that, The true density ρ of the electrolyte of the negative electrode active material E For ρ S -0.8g / cm 3 ~ρ S -0.75g / cm 3 .

8. The negative electrode sheet according to claim 3, characterized in that, The negative electrode active material satisfies (1-ρ) E / ρ He ) / (1-ρ E / ρ S )≥0.

91.

9. The negative electrode sheet according to any one of claims 1-8, characterized in that, The negative electrode active material includes hard carbon and / or soft carbon.

10. A battery, characterized in that, Includes the negative electrode sheet as described in any one of claims 1-9.

11. An electrical appliance, characterized in that, Includes the battery as described in claim 10.

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