Electrochemical apparatus and electronic apparatus including the same

Abstract

To provide an electrochemical device and an electronic device including the same with improved cycle characteristics.SOLUTION: An electrochemical device includes a negative electrode and an electrolyte, the negative electrode includes a negative electrode current collector and a negative electrode active material layer provided on at least one surface of the negative electrode current collector, the negative electrode active material layer includes a first region and a second region, a thickness D1 of the first region at an arbitrary position is smaller than an average thickness D2 of the second region, and the electrolyte includes a salt having a P-O bond, the content of which is 0.05 g or less based on the first region per 1 cm2, the first region is located at an edge of the negative electrode active material layer, and the width of the first region is 15 μm or less.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to the field of energy storage technology, and more particularly to electrochemical apparatus and electronic apparatus including the same. Regarding the location, in particular, regarding lithium-ion batteries. [Background technology]

[0002] Electrochemical devices (e.g., lithium-ion batteries) have high energy density and high operating voltage. Features include lightweight design, low self-discharge rate, long cycle life, no memory effect, and environmental friendliness. Due to its advantages, smart products (electronic products such as mobile phones, laptops, and cameras), electricity In fields such as automobiles, power tools, drones, smart robots, and large-scale energy storage, and production It is widely applied in various industries. However, the rapid advancements in information and communication technology and the diversification of market needs are changing. With advancements in technology, for example, materials become thinner, lighter, have more diverse shapes, and have higher volumetric energy. For power supplies in electronic products, including density and mass energy density, higher safety and higher output. The demands and challenges in response are increasing.

[0003] In the preparation process of electrochemical equipment, an active material layer is typically formed on the surface of the current collector by a coating method. It can be done. However, due to limitations in the production process, this coating method results in a thinner edge thickness. The issue is unavoidable, and it negatively affects the characteristics of the electrochemical apparatus, especially its cyclic properties.

[0004] In view of this, an electrochemical apparatus and an electronic apparatus including the same, having improved cycle characteristics. It is necessary to provide this. [Overview of the project]

[0005] The embodiments of the present invention provide an electrochemical apparatus and an electronic apparatus including the same, thereby reducing the number of To solve at least one problem in the related art to some extent.

[0006] In one embodiment, the present invention provides an electrochemical device, the electrochemical device including a negative electrode and an electrolytic solution, the negative electrode including a negative electrode current collector and a negative electrode active material layer provided on at least one surface of the negative electrode current collector, the negative electrode active material layer including a first region and a second region, where the thickness D1 of the first region is smaller than the average thickness D2 of the second region, and the electrolytic solution includes a salt having a P—O bond, and based on the first region per 1 cm , the content of the salt having a P—O bond is 0.05 g or less. , Based on the first region per 1 cm, the content of the salt having a P—O bond is 0.05 g or less. Based on the first region per 1 cm, the content of the salt having a P—O bond is 0.05 g or less.

[0007] According to an embodiment of the present invention, D1 and D2 satisfy 0 < D1 ≦ D2 × 97%.

[0008] According to an embodiment of the present invention, the salt having a P—O bond is at least one of LiPO2F2, NaPO₂F₂, KPO₂F₂, CsPO₂F₂, lithium difluoro(bis(oxalato))phosphate (LiDFOP), and lithium tetrafluorooxalatophosphate (LiTFOP). F2, KPO2F2, CsPO2F2, lithium difluoro(bis(oxalato))phosphate ( LiDFOP), and lithium tetrafluorooxalatophosphate (LiTFOP). At least one of them is included.

[0009] According to an embodiment of the present invention, the electrolytic solution further includes a first additive, the first additive being at least one of 1,3 - propanesultone, fluoroethylene carbonate, vinylene carbonate, succinic anhydride, and maleic anhydride.

[0010] According to an embodiment of the present invention, based on the first region per 1 cm<00,00002>, the content of the first additive is 0.001 g to 0.2 g.

[0011] According to an embodiment of the present invention, the electrolyte further comprises a second additive, and the second additive is , lithium tetrafluoroborate (LiBF4), lithium bis(fluorosulfonyl) LiFSI (Lithium Bis(Trifluoromethanesulfonyl)imide (LiTFS) I) Lithium 4,5-dicyano-2-(trifluoromethyl)imidazole (LiTD I) Lithium difluoro(oxalato)borate (LiDFOB), Lithium bis(oxalato) Salate, borate (LiBOB), adiponitrile (AND), succinonitrile (S N), 1,3,6-Hexanetricarbonitric (HTCN), 1,2,3-Tris(2-S) Anoxy)propane, 1,4-dicyano-2-butene, glutaronitrile, and Tris It comprises at least one (2-cyanoethyl)phosphine, and based on the weight of the electrolyte The content of the second additive is 0.1 wt% to 10 wt%.

[0012] According to an embodiment of the present invention, the first region is located at the edge of the negative electrode active material layer, The width of the first region is 15 μm or less.

[0013] According to an embodiment of the present invention, the area of ​​the first region is 20% of the total area of ​​the negative electrode active material layer. The following applies:

[0014] According to an embodiment of the present invention, the negative electrode active material layer comprises a negative electrode active material, and the negative electrode active material The median diameter is 5 μm to 20 μm.

[0015] According to an embodiment of the present invention, the compressed density of the negative electrode is 1.3 g / cm³. 3 ~1.8g / cm 3 in be.

[0016] In other embodiments, the present invention provides an electronic device, the electronic device being an electronic device as described above. Includes vapor chemistry equipment.

[0017] Other aspects and advantages of embodiments of the present invention are partially described, shown, or otherwise described in the following description. This is to be interpreted as an embodiment of the invention being practiced. [Brief explanation of the drawing]

[0018] In the following sections, examples of the present invention or prior art will be described in order to illustrate embodiments of the present invention. The necessary drawings for this purpose are outlined below. The drawings described below clearly illustrate the practical aspects of the present invention. This is only a part of the examples. For those skilled in the art, without requiring any creative effort, this still applies. Drawings of other embodiments can be obtained from the structures illustrated in these drawings. [Figure 1] Figure 1 is a schematic diagram showing the thinning region of the negative electrode active material layer. [Figure 2] Figure 2 is a schematic diagram showing the location of the thinned region of the negative electrode active material layer. [Figure 3] Figure 3 is a schematic diagram showing the location of the thinning regions of other negative electrode active material layers. [Figure 4] Figure 4 is a schematic diagram showing the locations of further thinning regions of the negative electrode active material layer. [Modes for carrying out the invention]

[0019] The embodiments of the present invention will be described in detail below. Throughout the specification of the present invention, the same or similar embodiments will be described. Components and components having the same or similar functions are indicated by similar reference numerals. The drawings and associated embodiments are illustrative and schematic and are used to provide a general understanding of the present invention. The embodiments of the present invention should not be construed as limiting the present invention.

[0020] Unless otherwise specified, the following terms used herein have the meanings set forth below. .

[0021] The term "approximately" is used to describe and explain small changes. Example Or, when used in combination with a situation, the aforementioned terms mean that the case or situation exactly occurred. An example can refer to a case or situation in which very similar circumstances occurred. When used in combination with a numerical value, the term refers to a range of change of ±10% or less of the numerical value. For example, ±5% or less, ±4% or less, ±3% or less, ±2% or less, ±1% or less, ±0.5% The following can refer to ±0.1% or less, or ±0.05% or less. In some cases, quantities, ratios, and other numerical values ​​may be expressed in the form of a range. The format is intended for convenience and conciseness and should be interpreted flexibly. This format is a range. In addition to including the numerical values ​​explicitly specified in the range limits, each of the following is included in the range: This includes numerical values ​​or subranges, where each numerical value or subrange is clearly specified. It corresponds to this.

[0022] In the modes and claims for carrying out the invention, the term "at least one" Therefore, the list of connected terms can represent any combination of the listed terms. For example, if items A and B are listed, the phrase "at least one of A and B" can be used. " means A only, B only, or A and B. In other examples, term A, term B, and If item C is listed, then "at least one of A, B, and C" means A only, B only , C only, A and B (excluding C), A and C (excluding B), B and C (excluding A), or A, This refers to all of B and C. Term A may contain a single element or multiple elements. Term B This may include a single element or multiple elements. Item C may include a single element or multiple elements It may include.

[0023] When preparing electrochemical equipment (for example, lithium-ion batteries), the active material depends on the coating method. The slurry is applied to the current collector to form an active material layer, and then the electrodes are prepared. However, the coating The active material slurry has a certain fluidity, and there are limitations to conventional production processes, and the active material on the current collector In a material layer, the phenomenon where the thickness of the edge region is smaller than the thickness of the central region is unavoidable. i. As shown in Figure 1, the active material layer on the current collector has a first region in which the thickness gradually decreases (i.e., It includes a thin-layer region and a second region with nearly uniform thickness. The presence of the thin-layer region is an indication of the electrochemical apparatus. This adversely affects the properties. For example, in the thinned region of the negative electrode, the electrolyte and the negative electrode come into contact. The interface deteriorates, stress becomes non-uniform, leading to increased polarization and lithium at the negative electrode. There is insufficient space for absorption, and there is a difference in current distribution in the negative electrode active material layer during the initial charging process. This delays film formation in the thin-layer region. These factors affect the cycle process of the electrochemical apparatus. This leads to an increase in side reactions, making lithium deposition more likely and resulting in poor cycle characteristics. Yes.

[0024] To solve the above problems, the present invention provides a salt having a PO bond in a specific content. By using an electrolyte, the adverse effects caused by the thinning of the negative electrode active material layer are compensated for, and the electrochemical process The cycle characteristics of the electrode were improved. Specifically, the present invention relates to the positive electrode, negative electrode, and electrolyte described below. The present invention provides an electrochemical apparatus that includes [something]. In some embodiments, the electrochemical apparatus is [something]. Further, it includes a separator provided between the positive electrode and the negative electrode.

[0025] Negative electrode The negative electrode used in the electrochemical device of the present invention includes a negative electrode current collector and at least one negative electrode active material layer provided on one surface thereof, and the negative electrode active material layer includes a first region and a second region, and the thickness D1 at any position in the first region is smaller than the average thickness D 2 of the second region.

[0026] In some embodiments, D1 and D2 satisfy 0 < D1 ≤ D2 × 97%.

[0027] In some embodiments, the first region is located at the edge of the negative electrode active material layer, and the width of the first region is 15 μm or less. In some embodiments, the width of the first region is 12 μm or less. In some embodiments, the width of the first region is 10 μm or less . In some embodiments, the width of the first region is 8 μm or less. In some embodiments the width of the first region is 5 μm or less. The "width of the first region" is the distance from the boundary position between the negative electrode current collector without the negative electrode active material coated thereon and the negative electrode current collector with the negative electrode active material coated thereon to the position where the thickness of the negative electrode active material layer becomes 97% of the thickness of the central region of the negative electrode active material layer. The "width of the first region" may also be the distance from the edge position of the negative electrode active material layer to the position where the thickness of the negative electrode active material layer becomes 97% of the thickness of the central region of the negative electrode active material layer. When the width of the first region is within the above range, the thinning region of the negative electrode active material layer is small, which contributes to improving the cycle characteristics of the electrochemical device. When the width of the first region is within the above range, the thinning region of the negative electrode active material layer is small, which contributes to improving the cycle characteristics of the electrochemical device.

[0028] In some embodiments, the area of the first region is 20% of the total area of the negative electrode active material layer. ​​​​​​​​​The following applies: In some embodiments, the area of ​​the first region is the total surface of the negative electrode active material layer. It is 18% or less of the product. In some embodiments, the area of ​​the first region is the negative electrode active material It is 15% or less of the total area of ​​the layer. In some embodiments, the area of ​​the first region is The area of ​​the negative electrode active material layer is 12% or less of the total area. In some examples, the first region The area of ​​the negative electrode active material layer is 10% or less of the total area of ​​the negative electrode active material layer. In some embodiments, the The area of ​​the first region is 8% or less of the total area of ​​the negative electrode active material layer. In some embodiments... Furthermore, the area of ​​the first region is 5% or less of the total area of ​​the negative electrode active material layer. The smaller the product, the higher the requirements for the process and the higher the process cost. (Negative electrode active material layer) If the area of ​​the first region in relation to the total area is within the above range, then the thinning region of the negative electrode active material layer This effectively reduces the adverse effects and does not significantly increase the cost of additional processes, The cycle characteristics of the device can be improved.

[0029] In some embodiments, the negative electrode active material layer includes a negative electrode active material. In the example, the negative electrode active material electrochemically absorbs and releases metal ions such as lithium ions. It is any possible material. In some embodiments, the negative electrode active material is a carbonaceous material , silicon-carbon materials, alloy materials, and lithium-containing metal composite oxide materials, one or more types Includes.

[0030] In some embodiments, the median diameter of the negative electrode active material is 5 μm to 20 μm. In some examples, the median diameter of the negative electrode active material is 8 μm to 18 μm. In several embodiments, the median diameter of the negative electrode active material is 10 μm to 15 μm. In several embodiments, the median diameter of the negative electrode active material was 5 μm, 8 μm, 10 μm, 1 The values ​​are 2 μm, 15 μm, 18 μm, or 20 μm, or any two of the above values. It is within the range. "Median diameter" refers to the particle size distribution of the negative electrode active material based on volume. This refers to the particle size at which the cumulative volume from the smallest particle size side becomes 50%, i.e., smaller than the particle size in question. The volume of the negative electrode active material accounts for 50% of the total volume of the negative electrode active material. The median diameter of the negative electrode active material is If the results fall within the above range, the cycle characteristics of the electrochemical apparatus can be further improved.

[0031] In some embodiments, the negative electrode active material layer further includes a negative electrode binder. In several embodiments, the negative electrode binder is styrene-butadiene rubber, fluorine-based rubber, etc. It contains one or more types of ethylenepropylene diene.

[0032] In some embodiments, the negative electrode active material layer further comprises a negative electrode conductive agent. In that embodiment, the negative electrode conductive agent is a conductive metal material and a conductive polymer. Includes one or more types. In some examples, the negative electrode conductive agent is a type of carbon material. or includes multiple types. In some embodiments, the carbon material is graphite, carbon bra This includes, but is not limited to, black, acetylene black, and Ketjenblack.

[0033] In some embodiments, the compressed density of the negative electrode is 1.3 g / cm³. 3 ~1.8g / cm 3 In some embodiments, the compressed density of the negative electrode is 1.4 g / cm³. 3 ~1.6g / cm 3 In some embodiments, the compressed density of the negative electrode is 1.5 g / cm³.3 is .

[0034] In some embodiments, the negative electrode current collector includes a negative electrode conductive material. In some embodiments the negative electrode current collector includes, but is not limited to, copper, nickel, and stainless steel. In some embodiments, the surface of the negative electrode current collector is roughened, and the roughened surface can improve the adhesion of the negative electrode active material. In some embodiments, the roughened negative electrode current collector includes, but is not limited to, electrolytic copper foil.

[0035] In some embodiments, a negative electrode active material layer is provided on one surface of the negative electrode current collector. In some embodiments, negative electrode active material layers are provided on both surfaces of the negative electrode current collector. In some embodiments, there is a region where no negative electrode active material layer is provided on at least one surface of the negative electrode current collector, which is also called an empty foil region.

[0036] Electrolyte The electrolyte used in the electrochemical device of the present invention contains a salt having a P—O bond, and based on the first region per 1 cm 2 the content of the salt having a P—O bond is 0.05 g or less.

[0037] In some embodiments, the salt having a P—O bond is an inorganic salt having a P—O bond.

[0038] In some embodiments, the salt having a P—O bond includes at least one of LiPO2F2, NaPO 2F2, KPO2F2, CsPO2F2, lithium difluorobis(oxalato)phosphate , and lithium difluorodioxalatophosphate (LIDODFP).

[0039] In some examples, 1 cm 2 Based on the first region per unit, the PO connection The salt content containing the compound is 0.04 g or less. In some examples, 1 cm 2 Current Based on the first region of the above, the content of the salt having the PO bond is 0.03 g or less. Yes. In some examples, 1 cm 2 Based on the first region per unit, the P- The salt content containing oxygen bonds is 0.02 g or less. In some examples, 1 cm 2 Based on the first region per unit, the content of the salt having the PO bond is 0.01 g or less. Below. In some examples, 1 cm 2 Based on the first region per unit, The content of salts having PO bonds is 0.005 g or less. In some examples, 1cm 2 Based on the first region per unit, the content of the salt having the PO bond is 0.0 g is 0.1 or less. In some examples, 1 cm 2 Based on the aforementioned first region The content of the salt having the PO bond is 0.0005 g or less.

[0040] When an electrochemical apparatus is initially charged, salts containing PO bonds preferentially accumulate on the negative electrode surface. In addition to contributing to the deposition of the second region of the negative electrode active material layer, more importantly, the negative electrode active material layer It also contributes to the formation of the first region, thereby improving the stability of the formed film and the negative electrode active material Reduce the occurrence of side reactions in the first region of the layer and reduce thickness changes due to by-products in the first region. Furthermore, the use of salts containing PO bonds enhances the cycle stability of electrochemical equipment. To reduce the adverse effects caused by the difference in current distribution between the first and second regions of the negative electrode active material layer. This contributes to ensuring the effectiveness of film formation in the first region of the negative electrode active material layer. The electrolyte contains the above content. Including a salt having a PO bond reduces the adverse effects caused by the thinning of the negative electrode active material layer. This significantly improves the cycle characteristics of electrochemical equipment.

[0041] In some embodiments, the electrolyte further comprises the first additive, and the first additive The reduction potential is 2.5V or less. If the reduction potential of the first additive is 2.5V or less, This allows for the formation of a protective layer on the polar surface, thereby reducing the adverse effects caused by the thinning of the negative electrode active material layer. This significantly improves the cycle characteristics of electrochemical equipment.

[0042] In some embodiments, the first additive is 1,3-propanesultone (PS), Fluoroethylene carbonate (FEC), vinylene carbonate (VC), anhydrous succinate It contains an acid and at least one of maleic anhydride.

[0043] In some embodiments, the first additive is 1,3-propanesultone (PS) and Contains fluoroethylene carbonate (FEC).

[0044] In some embodiments, the weight of 1,3-propanesultone in the electrolyte The fraction is greater than the weight fraction of the fluoroethylene carbonate in the electrolyte. In some embodiments, the weight of 1,3-propanesultone in the electrolyte The ratio of the rate to the weight fraction of the fluoroethylene carbonate in the electrolyte is 1.5 or less. Below. When the ratio of weight fractions is within this range, the cycle characteristics of the electrochemical apparatus can be improved. This also reduces the amount of gas generated by the electrochemical apparatus.

[0045] In some embodiments, the first additive is 1,3-propanesultone (PS) and It contains fluoroethylene carbonate (FEC) and vinylene carbonate (VC). .

[0046] In some examples, 1 cm 2 Based on the first region per unit, the first addition The amount of the agent is 0.001g to 0.2g. In some examples, 1cm 2 Winner Based on the aforementioned first region, the content of the first additive is 0.005g to 0.2g. In several examples, 1 cm 2 Based on the first region per unit, the first additive The content is 0.01g to 0.15g. In some examples, 1cm 2 Of course Based on the first region, the content of the first additive is 0.05g to 0.13g. In that embodiment, 1 cm 2 Based on the first region per unit, the content of the first additive The amount is 0.08g to 0.1g. In some examples, 1cm 2 The first hit Based on the region, the content of the first additive is 0.001g, 0.005g, 0.01g, and 0. 0.3g, 0.05g, 0.07g, 0.1g, 0.15g, or 0.2g, or The content of the first additive in the electrolyte is within the range of any two of the above values. When placed within an enclosure, it contributes to further improving the cycle characteristics of the electrochemical apparatus.

[0047] In some embodiments, the electrolyte further comprises a second additive, and the second additive These are lithium tetrafluoroborate (LiBF4) and lithium bisfluorosulfonylurea. LiFSI (Lithium Bis(Trifluorosulfonyl)imide (LiTFSI), 4,5-Dicyano-2-trifluoromethylimidazole lithium (LiTDI), Lithium Um difluoro(oxalato)borate (LiDFOB), lithium bis(oxalate) Borate, adiponitrile (ADN), succinonitrile, 1,3,6-hexanetrical Bonitrile (HTCN), 1,2,3-Tris(2-cyanoxy)propane, 1,4-Disyl A small amount of ano-2-butene, glutaronitrile, and tris(2-cyanoethyl)phosphine It contains at least one type. In some examples, the second additive is LiBF4 and Li It includes DFOB. In some examples, the second additive is HTCN and LiDF It includes OB. In some examples, the second additive is LiBF4 and LiDF It contains OB and LiTFSI. In some examples, the second additive is HTC It includes N, LiDFOB, and LiTFSI.

[0048] The second additive forms a protective layer on the positive electrode surface, reducing the occurrence of side reactions at the positive electrode, and further It can reduce the elution of metal ions from the positive electrode. It protects the negative electrode during the cyclic process of an electrochemical apparatus. The stability of the film is affected by the products of side reactions at the positive electrode. Therefore, the second additive is It protects both the positive and negative electrodes, and plays a role in the cycle characteristics of the electrochemical apparatus. It contributes to improvement.

[0049] In some embodiments, the content of the second additive is determined based on the weight of the electrolyte. The content of the second additive is 0.1 wt% to 10 wt% based on the weight of the electrolyte. The amount is 0.2 wt% to 5 wt%. In some examples, based on the weight of the electrolyte Therefore, the content of the second additive is 0.5 wt% to 3 wt%. In some examples... Based on the weight of the electrolyte, the content of the second additive is 1 wt% to 2 wt%. In some examples, the content of the second additive is determined based on the weight of the electrolyte. The amounts are 0.1 wt%, 0.5 wt%, 1 wt%, 2 wt%, 3 wt%, 4 wt%, and 5 wt%. 6wt%, 7wt%, 8wt%, 9wt%, or 10wt%, or any of the above. It is within the range of the two values. When the content of the second additive in the electrolyte is within the above range. This contributes to further improving the cycle characteristics of electrochemical equipment.

[0050] The electrolyte used in the present invention contains LiPF6. In some examples, LiPF The concentration of 6 is in the range of 0.8 mol / L to 3 mol / L, and 0.8 mol / L to 2.5 m It is within the range of ol / L, within the range of 0.8 mol / L to 2 mol / L, or 1 mo The concentration is in the range of l / L to 2 mol / L. In some examples, the concentration of the lithium salt is , about 1mol / L, about 1.15mol / L, about 1.2mol / L, about 1.5mol / L, about It is 2 mol / L, or approximately 2.5 mol / L.

[0051] The solvent used in the electrolyte in the embodiments of the present invention is a cyclic carbonate, a chain carbonate Ether, cyclic carboxylic acid ester, linear carboxylic acid ester, cyclic ether, linear ether This includes phosphorus-containing organic solvents, sulfur-containing organic solvents, and aromatic fluorine-containing solvents, but these include Not limited.

[0052] In some examples, the cyclic carbonate is ethylene carbonate (EC), p This includes, but is not limited to, polypropylene carbonate (PC) and butylene carbonate. No. In some examples, the cyclic carbonate has 3 to 6 carbon atoms.

[0053] In some examples, the linear carbonate is dimethyl carbonate, ethylmeth Carbonate, diethyl carbonate (DEC), methyl-n-propyl carbonate, Chain-like carbonates such as ethyl-n-propyl carbonate and di-n-propyl carbonate , as a fluorine-substituted chain carbonate, for example, bis(fluoromethyl)carbon nate, bis(difluoromethyl)carbonate, bis(trifluoromethyl)carbonate Bis(2-fluoroethyl) carbonate, bis(2,2-difluoroethyl) carbonate Carbonate, bis(2,2,2-trifluoroethyl) carbonate, 2-fluoroethyl Tyl carbonate, 2,2-difluoroethylmethyl carbonate, and 2,2,2-tri This includes, but is not limited to, fluoroethyl methyl carbonate.

[0054] In some examples, the cyclic carboxylic acid ester is γ-butyrolactone, and γ- This includes, but is not limited to, valerolactones. In some examples, cyclic calcium carbonate Some of the hydrogen atoms in the von acid ester may be substituted with fluorine.

[0055] In some examples, the linear carboxylic acid ester is methyl acetate, ethyl acetate, vinegar Propyl acetate, isopropyl acetate, butyl acetate, sec-butyl acetate, isobutyl acetate, vinegar t-butyl acid, methyl propionate, ethyl propionate, propyl propionate, pro Isopropyl pionate, methyl butyrate, ethyl butyrate, propyl butyrate, methyl isobutyrate, iso Contains ethyl butyrate, methyl valerate, ethyl valerate, methyl pivalate, and ethyl pivalate. However, it is not limited to these. In some examples, the hydrogen of the chain carboxylic acid ester A portion of the chain may be substituted with fluorine. In some examples, the fluorine-substituted chain Examples of carboxylic acid esters include methyl trifluoroacetate, ethyl trifluoroacetate, and trifluoroacetate. Propyl oroacetate, butyl trifluoroacetate, and 2,2,2-trifluoroacetate This includes, but is not limited to, ruoroethyl.

[0056] In some examples, the cyclic ether is tetrahydrofuran, 2-methyltetra Hydrofuran, 1,3-dioxolane, 2-methyl-1,3-dioxolane, 4-methyl- 1,3-Dioxolane, 1,3-Dioxane, 1,4-Dioxane, and dimethoxypro This includes, but is not limited to, bread.

[0057] In some examples, the linear ether is dimethoxymethane, 1,1-dimethoxy Ethane, 1,2-dimethoxyethane, diethoxymethane, 1,1-diethoxyethane, 1 ,2-diethoxyethane, ethoxymethoxymethane, 1,1-ethoxymethoxyethane, This includes, but is not limited to, 1,2-ethoxymethoxyethane.

[0058] In some examples, the phosphorus-containing organic solvent was trimethyl phosphate, triethyl phosphate. methyl ethyl phosphate, methyl diethyl phosphate, ethylene methyl phosphate, ethyl phosphate Lenthyl, triphenyl phosphate, trimethyl phosphate, triethyl phosphate, phosphorous acid Triphenyl, tris(2,2,2-trifluoroethyl) phosphate, and tris( This includes, but is not limited to, 2,2,3,3,3-pentafluoropropyl.

[0059] In some examples, the sulfur-containing organic solvents were sulfolane and 2-methylsulfolane. 3-methylsulfolane, dimethyl sulfone, diethylsulfone, ethylmethylsulfone Methylpropyl sulfone, dimethyl sulfoxide, methyl methanesulfonate, methanesulfonate Ethyl sulfonate, methyl ethanesulfonate, ethyl ethanesulfonate, dimethyl sulfate, sulfur This includes, but is not limited to, diethyl acid and dibutyl sulfate. In some examples... Furthermore, some of the hydrogen atoms in the sulfur-containing organic solvent may be replaced with fluorine.

[0060] In some examples, the aromatic fluorine-containing solvent is fluorobenzene, difluoro Benzene, trifluorobenzene, tetrafluorobenzene, pentafluorobenzene, This includes, but is not limited to, hexafluorobenzene and trifluoromethylbenzene. do not have.

[0061] In some embodiments, the solvent used in the electrolyte of the present invention is one or more of the above-mentioned solvents. It contains a variety of solvents. In some examples, the solvent used in the electrolyte of the present invention is cyclic. Carbonates, linear carbonates, cyclic carboxylic acid esters, linear carboxylic acid esters, and combinations thereof. In some embodiments, the electrolyte used in the present invention The solvents are ethylene carbonate, propylene carbonate, diethyl carbonate, pro Ethyl pionate, propyl propionate, n-propyl acetate, ethyl acetate, and the same The present invention contains an organic solvent selected from the group consisting of combinations. The solvents used in the electrolyte are ethylene carbonate, propylene carbonate, and dieth Carbonate, ethyl propionate, propyl propionate, γ-butyrolactone, and This includes combinations of those.

[0062] positive electrode The positive electrode includes a positive electrode current collector and a positive electrode active material provided on the positive electrode current collector. There are no specific limitations on the types of quality; you can choose as needed.

[0063] In some embodiments, the positive electrode active material is capable of intercalating and deintercalating lithium (Li). Includes positive electrode material. An example of a positive electrode material capable of intercalating and releasing lithium (Li) is cobalt. Lithium oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminate Lithium manganese, lithium iron manganese phosphate, lithium vanadium phosphate, phosphorus Lithium vanadyl phosphate, lithium iron phosphate, lithium titanate, and lithium-rich manganese It may contain ion-based materials.

[0064] Specifically, the chemical formula for lithium cobaltate may also be chemical formula 1. Li x Co a M1 b O 2-c chemical formula 1

[0065] M1 consists of nickel (Ni), manganese (Mn), magnesium (Mg), and aluminum. (Al), Boron (B), Titanium (Ti), Vanadium (V), Chromium (Cr), Iron (F) e) Copper (Cu), zinc (Zn), molybdenum (Mo), tin (Sn), calcium (C) a) Strontium (Sr), tungsten (W), yttrium (Y), lanthanum ( Selected from La, zirconium (Zr), silicon (Si), fluorine (F), and sulfur (S). It represents at least one element, and the values ​​of x, a, b, and c are, respectively, 0.8 ≤ x ≤ It is within the range of 1.2, 0.8 ≤ a ≤ 1, 0 ≤ b ≤ 0.2, and -0.1 ≤ c ≤ 0.2.

[0066] Lithium nickel-cobalt manganese or lithium nickel-cobalt aluminate The formula may also be chemical formula 2. Li y Ni d M2 e O 2-f chemical formula 2

[0067] M2 consists of cobalt (Co), manganese (Mn), magnesium (Mg), and aluminum. (Al), Boron (B), Titanium (Ti), Vanadium (V), Chromium (Cr), Iron (F) e) Copper (Cu), zinc (Zn), molybdenum (Mo), tin (Sn), calcium (C) a) Strontium (Sr), tungsten (W), zirconium (Zr), silicon ( It represents at least one element selected from Si (silicon), fluorine (F), and sulfur (S), and y, The values ​​of d, e, and f are 0.8 ≤ y ≤ 1.2, 0.3 ≤ d ≤ 0.98, and 0.02, respectively. The values ​​are within the ranges ≤e ≤ 0.7 and -0.1 ≤ f ≤ 0.2.

[0068] The chemical formula for lithium manganate may also be chemical formula 3. Li z Mn 2-g M3 g O 4-h chemical formula 3

[0069] M3 is composed of cobalt (Co), nickel (Ni), magnesium (Mg), and aluminum. (Al), Boron (B), Titanium (Ti), Vanadium (V), Chromium (Cr), Iron (F) e) Copper (Cu), zinc (Zn), molybdenum (Mo), tin (Sn), calcium (C) a) Strontium (Sr), niobium (Nb), tantalum (Ta), and tungsten (W) represents at least one element selected from (W), where the values ​​of z, g, and h are 0, respectively. The values ​​are within the ranges 8≦z≦1.2, 0≦g<1.0, and -0.2≦h≦0.2.

[0070] In some embodiments, the positive electrode active material layer may have a coating on its surface, or It may be mixed with another compound having a coating. The coating is applied Oxides of coated elements, hydroxides of coated elements, oxyhydroxides of coated elements The oxycarbonate of the applied element, and the coated element At least one selected from hydroxycarbonates The coating may contain a compound of one of the coated elements. The compound used for the coating is Amo It may be rufus or crystalline. The coated elements contained in the coating are Mg, Al, Co, K, Na, Ca, Si, Ti, V, Sn, Ge, Ga, B, As, Z It may contain r, F, and mixtures thereof, as long as it does not adversely affect the properties of the positive electrode active material. The coating may be formed by any method. For example, the method may involve spraying, dip, etc. This may include any application method known to those skilled in the art, such as topping.

[0071] In some embodiments, the positive electrode active material layer further comprises a binder and, optionally It further includes a positive electrode conductive material.

[0072] The binder enhances the bonding between positive electrode active material particles and also enhances the bonding between the positive electrode active material and the current collector. It can be used. Non-limiting examples of binders include polyvinyl alcohol and hydroxypropyl alcohol. Dipropylcellulose, diacetylcellulose, polyvinyl chloride, carboxylated Polyvinyl chloride, polyvinyl fluoride, polyvinylpyrrolidone, polyurethane, Tetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, s Tylene butadiene rubber, acrylic (ester) styrene butadiene rubber, epoxy resin , including nylon, etc.

[0073] The positive electrode active material layer contains a positive electrode conductive material to impart conductivity to the electrode. The positive electrode conductive material is Any conductive material may be included, as long as it does not cause a chemical reaction. As an example, carbon-based materials (e.g., natural graphite, artificial graphite, carbon black, acetylene) (e.g., black, Ketjenblack, carbon fiber), metallic materials (e.g., copper, nickel) Metal powders containing aluminum, silver, etc., metal fibers, etc., conductive polymers (for example, This includes polyphenylene derivatives and mixtures thereof.

[0074] The positive electrode current collector used in the electrochemical apparatus according to the present invention is made of aluminum (Al). That's fine, but it's not limited to that.

[0075] Separator In some embodiments, the electrochemical apparatus of the present invention has a separator between the positive electrode and the negative electrode. By providing this, a short circuit of current due to contact between the two pole pieces is prevented, and lithium io It can pass through.

[0076] The material and shape of the separator used in the electrochemical apparatus of the present invention are not particularly limited, and prior art It may be any of those disclosed in the technology. In some embodiments, the separator is , a polymer (e.g., synthetic resin) formed from a material that is stable to the electrolyte of the present invention. or inorganic materials (e.g., ceramics), etc. In some embodiments, the separator The material includes a porous membrane made of the polymer or the inorganic material. In some examples, The separator includes a laminated film formed by stacking two or more types of porous films. Several implementations In the example, the polymer is polytetrafluoroethylene, polypropylene, and polyethylene. This includes, but is not limited to, ethylene.

[0077] In some embodiments, the separator comprises the porous film (substrate material layer) and the base It includes a polymer compound layer provided on one or two surfaces of a plate material layer, thereby The separator improves adhesion between the positive and negative electrodes, and reduces strain when winding the electrode pieces. By suppressing the growth of electrolyte, the decomposition reaction of the electrolyte is suppressed, preventing leakage of the electrolyte that impregnates the substrate material layer. This can be suppressed. By using this separator, the charging / discharging cycle can be controlled. Even in combination, the expansion of the electrochemical apparatus is suppressed without a significant increase in the resistance of the electrochemical apparatus. It is possible.

[0078] In some examples, the polymer compound layer contains polyvinylidene fluoride, This is not limited to polyvinylidene fluoride, which has excellent physical strength and electrochemical stability. The polymer compound layer is formed after preparing a solution in which the polymer material is dissolved. By coating the substrate material layer with a liquid, or by immersing the substrate material layer in a solution, and finally drying it, It is acceptable for it to be formed.

[0079] use The electrochemical apparatus of the present invention includes any apparatus in which an electrochemical reaction occurs, and a specific example thereof is This includes all types of primary and secondary batteries. In particular, this electrochemical device uses lithium Metal secondary batteries, lithium-ion secondary batteries, lithium polymer secondary batteries, and lithium ion This is a lithium secondary battery, including polymer secondary batteries.

[0080] The use of the electrochemical apparatus of the present invention is not particularly limited and can be used with any electronic apparatus known in the prior art. It can be used. In one embodiment, the electrochemical apparatus of the present invention is a laptop computer. Pen-input computers, mobile computers, e-book players, portable computers Talk, portable fax machine, portable copier, portable printer, stereo headset, Video recorder, LCD TV, portable cleaner, portable CD player, mini-C D, transceiver, electronic notebook, calculator, memory card, portable tape recorder Orderer, radio, backup power supply, motor, automobile, motorcycle, electric assist bicycle, Bicycles, lighting fixtures, toys, game consoles, clocks, power tools, flashlights, cameras, large household items It may be used in storage batteries and lithium-ion capacitors, but It is not limited to them.

[0081] Examples The following describes the characterization of examples and comparative examples of lithium-ion batteries according to the present invention. To do so.

[0082] 1. Preparation of lithium-ion batteries Comparative Example 1 (1) Preparation of the negative electrode The negative electrode active material is artificial graphite (median diameter 12.0 μm), the conductive agent is SuperP, and the carbamide is carbamide. Sodium xymethylcellulose (CMC), with styrene-butadiene rubber as a binder. Mix (SBR) in a weight ratio of 96.4:1.5:0.5:1.6, add deionized water, and mix until uniform. The mixture was stirred to obtain a negative electrode slurry with a solid content of 54 wt%. The negative electrode slurry was then placed on a copper foil. The material is applied uniformly, dried at 85°C, and then cold-rolled, die-cut, slit, and wound. Afterward, it was dried under vacuum conditions at 120°C for 12 hours, and the length was 1544.0 ± 5.0 mm. A negative electrode with a width of 66.5 ± 1.0 mm was obtained, and the total area of ​​the negative electrode active material layer on one side (based on one side) ) is 1544.0 × 66.5 = 102676 (mm 2 ) and approximately 1027cm 2 and The compressed density of the negative electrode is 1.6 g / cm³. 3 That was the case.

[0083] The viscosity of the negative electrode slurry was adjusted according to the settings of the following comparative examples and examples, and different application specifications were achieved. Using a die, the distance from the coating die to the coating roll and the speed of the substrate on the conveyor belt are measured. The width and area of ​​the first region of the negative electrode active material layer were adjusted and controlled by means of control.

[0084] In Table 1, the width of the first region corresponding to the area of ​​the first region in each comparative example and example is shown in the table below. [Table A]

[0085] (2) Preparation of the positive electrode Li(Ni) is the positive electrode active material. 0.8 Co 0.08 Mn 0.07 )Al 0.05O2, conductive agent Super-P and polyvinylidene fluoride are mixed in a mass ratio of 97:1.4:1.6 with N-methyl Mix with lupyrolidone (NMP), stir uniformly, and obtain a positive result with a solid content of 72 wt%. An electrode slurry was obtained. This positive electrode slurry was applied to aluminum foil and dried at 85°C, and then After cold rolling, die cutting, slitting, and tab welding, the material is subjected to a vacuum at 85°C for 4 hours. The electrode was dried and the positive electrode was obtained.

[0086] (3) Preparation of electrolyte In a dry argon gas atmosphere, ethylene carbonate (EC), propylene carbonate Polymethyl carbonate (PC), Ethyl methyl carbonate (EMC), Diethyl carbonate (DEC) The mixture was combined in a mass ratio of EC:PC:DEC:EMC = 15:25:50:10 and compared with the example. Following the example setup, add the additive, dissolve it, and stir thoroughly, then add the lithium salt LiPF6. The mixture was then homogeneously mixed to obtain a base electrolyte with a LiPF6 concentration of 1.2 mol / L. .

[0087] According to the following comparative examples and examples, a salt having a PO bond was added to the base electrolyte. The agent and / or a second additive were added to obtain the electrolyte.

[0088] (4) Preparation of separators A polyethylene (PE) film with a thickness of 7 μm is used, and on top of it, a coating with a thickness of 3 μm is applied. As shown, the ratio of PVDF slurry to inorganic particles (sheet-like boehmite and Al2O3 is 70%) A slurry (30%) was applied and dried to obtain a separator.

[0089] (5) Preparation of lithium-ion batteries The obtained positive electrode, separator, and negative electrode are wound up in sequence to form a bare cell, and the bare cell is Placed on the outer foil, leaving an opening for the liquid injection. The electrolyte was poured into the opening, and the package and formation... (Charges up to 3.3V with a constant current of 0.02C, then charges up to 3.6V with a constant current of 0.1C) After going through processes such as capacity testing, the lithium-ion battery (with a thickness of approximately 9.1 mm and a width of approximately 49 mm) is produced. A value of approximately 74 mm in length was obtained.

[0090] 2.Measurement method (1) Method for measuring the cycle capacity retention rate and cycle thickness expansion rate of lithium-ion batteries Place the lithium-ion battery in a 25°C incubator and leave it undisturbed for 30 minutes. The temperature stabilized. The initial thickness H0 of the lithium-ion battery was measured. Charge the battery with a constant current of 1.0C until the voltage reaches 4.2V, and then set the constant voltage to 4.2V. Discharge it until the current drops to 0.05C, then charge it with a constant current of 4C until the voltage reaches 2.8V. The charging process is considered one charge-discharge cycle, and the capacity C0 of the first discharge is recorded. The system performs 600 charge-discharge cycles on a lithium-ion battery, then stops the measurement. The discharge capacity C1 and the thickness H1 of the lithium-ion battery after each cycle were recorded.

[0091] The cycle capacity retention rate and cycle thickness expansion rate of a lithium-ion battery are calculated using the following formula. I calculated it. Cycle capacity maintenance rate = C1 / C0 × 100% Cycle thickness expansion coefficient = (H1 - H0) / H0 × 100%

[0092] (2) Method for measuring the thickness of the first and second regions of the negative electrode active material layer When the negative electrode active material layer has the structure shown in Figure 2, the length axis is the cross-section, and the width direction is the center. Next, select a cross section with a length of 1 cm and use a digital microscope system (VHX-9 The thickness of the negative electrode active material layer is measured using 50F), and 10 points are arbitrarily selected to measure the total thickness of the negative electrode piece. Calculate the average value E0 and the average value of the current collector thickness E1, and then use the formula: D2 = (E0 - E1) / 2 The thickness D2 of the second region of the negative electrode active material layer was calculated.

[0093] With the central axis of length as the cross-section, at intervals of 0.1 mm from the edge region of the negative electrode active material layer, 1 The point is measured, and for any one side of the negative electrode active material layer, from the surface away from the current collector, this negative electrode active The thickness from the material layer to the surface of the current collector in contact with it is measured and defined as D1, and the thickness at five points is measured. If all three of those points satisfy D1 > D2 × 97%, then the efflation of the negative electrode active material layer The distance from the point closest to the edge to the negative electrode active material layer is defined as the width of the first region of the negative electrode active material layer. The thickness measurement unit above was set to an accuracy of 0.01 mm. During the measurement process, the cross-section The selection must include the first and second regions of the negative electrode active material layer.

[0094] When the negative electrode active material layer has the structure shown in Figure 3, in addition to using the central axis of the width as the cross-section, the above and The measurements were taken using almost the same method.

[0095] When the negative electrode active material layer has the structure shown in Figure 4, the central axis of length and the central axis of width are respectively In addition to determining the cross-section, measurements were taken using a method almost identical to that described above.

[0096] (3) Method for measuring the content of salts containing PO bonds in the electrolyte Discharge the lithium-ion battery at a rate of 0.2C until the voltage reaches 2.8V. The weight of the ON battery is measured and designated as M0, the tab and casing are cut off to obtain a bare cell, and the bare cell By centrifuging the solution, an electrolyte is obtained, and ion chromatography IC (model: thermo The anion content in the electrolyte was measured by Fischer (AQUION), and the electrolyte was then... The relative content Q of the salt having a PO bond was obtained. The centrifuged bare cell was dimethylated. Soaked in galvanic acid (DMC) for 72 hours and dried. Dry bare cells, tabs, and outer packaging. The total mass of the equipment was measured and designated as M1. The formula (M0-M1)×Q is used to determine the P in the bare cell. The mass of the salt containing an O bond was calculated. The mass of the salt containing a PO bond was calculated for the negative electrode active material layer. Divide by the total area of ​​one region, and the quality of the salt having PO bonds per unit area corresponding to the first region. A quantity was obtained.

[0097] The types of the first and second additives are ion chromatography IC (model: thermof Fisher, AQUION) or gas chromatograph GC (model: Agilent 78 Measured by 90A-5975C).

[0098] 3, Measurement results Table 1 shows the electrolyte composition and the first region in the negative electrode active material layer for each comparative example and example. This shows the effect on the cycle characteristics of lithium-ion batteries. Salts containing PO bonds or The amount of one additive per unit area is 1 cm 2 Based on the first region per unit, P- This is the weight of the salt or first additive having an oxygen bond. In each example and comparative example shown in Table 1, The total surface area of ​​the negative electrode active material layer on one side is 1027 cm². 2 That is the case.

[0099] [Table 1]

[0100] As shown in Comparative Examples 1 to 9, reducing the area of ​​the first region of the negative electrode active material layer is possible with lithium While it can improve the cycle capacity retention rate of ion batteries and reduce their thickness expansion rate, lithium Ion batteries have a low cycle capacity retention rate and a high thickness expansion rate, making it difficult to meet user needs. It is difficult.

[0101] As shown in Examples 1-13, the electrolyte was 0.05 g / cm³. 2 It has the following PO bond: When containing salts, it significantly improves the cycle capacity retention rate of lithium-ion batteries, and its thickness The expansion rate can be significantly reduced. As shown in Examples 34-37, different types of PO bonds can be used. The salts present, or combinations thereof, produce nearly identical effects.

[0102] As shown in Examples 14-20, the electrolyte was 0.001-0.2 g / cm³. 2 First additive If further including, it further improves the cycle capacity retention rate of lithium-ion batteries and its thickness This can reduce the rate of expansion.

[0103] As shown in Examples 21-27, the electrolyte contains 0.1 wt% to 10 wt% of a second additive. Furthermore, if included, it further improves the cycle capacity retention rate of lithium-ion batteries and their thickness The expansion rate can be reduced. As shown in Examples 28-33, the first additive and / or the second additive When using multiple agents in combination, the cycle capacity maintenance rate of lithium-ion batteries can be further improved. This allows for an increase in thickness, thereby reducing the rate of expansion.

[0104] Furthermore, if the area of ​​the first region is 20% or less of the total area of ​​the negative electrode active material layer, lithium io This further improves the battery's cycle capacity retention rate and reduces its thickness expansion rate.

[0105] Table 2 shows the effect of the median diameter of the negative electrode active material on the cycle characteristics of lithium-ion batteries. The preparation methods for Examples 38-41 and Example 3 are almost the same, but the parameters shown in Table 2 are different. The "ta" was different.

[0106] [Table 2]

[0107] As shown in Table 2, the median diameter of the negative electrode active material in the negative electrode active material layer is 5 μm to 20 μm. If so, it further improves the cycle capacity retention rate of lithium-ion batteries and their thickness expansion rate. It can be reduced.

[0108] Throughout the specification, the terms "several examples," "some examples," "one example," and "another example" are used. A reference by "example," "example," "specific example," or "partial example" of the present invention is at least one example of the present invention. One example or instance may have specific features, structures, materials or It means that the characteristics are included. Therefore, as stated in each place throughout the specification, for example, " In several examples, in an example, in one example, in another example In this case, "in one example," "in a particular example," or "example" does not necessarily mean this This specification does not refer to the same embodiments or examples of the invention. Furthermore, it does not refer to the specific features or structures described herein. The materials or properties may be any preferred method in one or more embodiments or examples. They can be combined.

[0109] While exemplary embodiments have been disclosed and described, those skilled in the art will see that the above embodiments do not limit the present invention. It shall not be interpreted as such, and shall not deviate from the technical concept, principles, and scope of the present invention. It should be understood that modifications, substitutions, and alterations to the examples are possible.

Claims

1. An electrochemical apparatus, It includes a negative electrode and an electrolyte, The negative electrode includes a negative electrode current collector and a negative electrode active material layer provided on at least one surface of the negative electrode current collector, the negative electrode active material layer includes a first region and a second region, the thickness D1 at any position in the first region is smaller than the average thickness D2 of the second region, and The electrolyte is 1 cm ２ It contains a salt having a P-O bond, with a content of 0.05 g or less per unit based on the first region, The salt having the P-O bond includes at least one of LiPO₂F₂, NaPO₂F₂, KPO₂F₂, CsPO₂F₂, lithium difluorobis(oxalato)phosphate, and lithium tetrafluorooxalatophosphate. The first region is located at the edge of the negative electrode active material layer, and the width of the first region is 15 μm or less. Electrochemical apparatus.

2. D1 and D2 satisfy the condition D1 ≤ D2 × 97%. The electrochemical apparatus according to claim 1.

3. The electrolyte further comprises a first additive, the first additive comprising at least one of 1,3-propanesultone, fluoroethylene carbonate, vinylene carbonate, succinic anhydride, and maleic anhydride. The electrochemical apparatus according to claim 1.

4. 1 cm ２ Based on the first region per unit area, the content of the first additive is 0.001 g to 0.2 g. The electrochemical apparatus according to claim 3.

5. The electrolyte further comprises a second additive, the second additive comprising at least one of lithium tetrafluoroborate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, 4,5-dicyano-2-trifluoromethylimidazole lithium, lithium difluoro(oxalato)borate, lithium bis(oxalate)borate, adiponitrile, succinonitrile, 1,3,6-hexanetricarbonitride, 1,2,3-tris(2-cyanoxy)propane, 1,4-dicyano-2-butene, glutalonitrile, and tris(2-cyanoethyl)phosphine, and the content of the second additive is 0.1 wt% to 10 wt% based on the weight of the electrolyte. The electrochemical apparatus according to claim 1.

6. The area of ​​the first region is 20% or less of the total area of ​​the negative electrode active material layer. The electrochemical apparatus according to claim 1.

7. The negative electrode active material layer contains a negative electrode active material, and the median diameter of the negative electrode active material is 5 μm to 20 μm. The electrochemical apparatus according to any one of claims 1 to 6.

8. The electrochemical apparatus includes the one described in any one of claims 1 to 7. electronic equipment.

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