Electrochemical device and electronic device comprising the same

Abstract

The invention relates to an electrochemical device and an electronic device comprising the same. The electrochemical device comprises a positive electrode, a negative electrode and an electrolyte, wherein the positive electrode comprises a positive electrode current collector, and a positive electrode active material region, an insulation region and an interaction region which are positioned on the positive electrode current collector; the interaction region is positioned between the positive active material region and the insulation region and is connected with the positive active material region and the insulation region; the positive active material region comprises a positive active material; the insulating region comprises an inorganic filler; the interaction region comprises the positive active material and the inorganic filler; and the electrolyte includes at least one of a compound having a cyano group or a compound having a sulfur-oxygen double bond. The electrochemical device provided by the invention has improved intermittent cycle performance and safety performance under high temperature and high pressure.

Description

[0001] This application is a divisional application of Chinese patent application filed on September 30, 2021, with application number 202180012300.X and entitled "Electrochemical Device and Electronic Device Including the Thereof". Technical Field

[0002] This application relates to the field of energy storage, specifically to an electrochemical device and an electronic device comprising the same, particularly a lithium-ion battery. Background Technology

[0003] Lithium-ion batteries are widely used in electric vehicles and consumer electronics due to their advantages such as high energy density, high output power, long cycle life, and low environmental pollution. However, lithium-ion batteries are prone to catching fire and exploding under abnormal conditions such as compression, impact, or puncture, causing serious hazards. Therefore, the safety issues of lithium-ion batteries greatly limit their application and widespread use.

[0004] When an internal short circuit occurs in a battery due to abnormal conditions such as collision, compression, or puncture, the battery temperature will rise. Existing technologies include adding a low-melting-point alloy to the metal current collector material. As the battery temperature rises, the low-melting-point alloy in the current collector melts, causing an open circuit at the electrode and thus cutting off the current, thereby improving battery safety. Alternatively, a multi-layer current collector with a resin layer and metal layers on both sides can be used. As the battery temperature rises, when the melting point of the resin layer material is reached, the resin layer of the current collector melts, causing the electrode to break, thereby cutting off the current and improving battery safety.

[0005] However, existing methods cannot effectively prevent internal short circuits in lithium-ion batteries, nor can they guarantee that the battery will continue to operate after abnormal conditions occur. Therefore, it is necessary to provide a battery design that can effectively prevent fires, explosions, and other accidents caused by internal short circuits after abnormal conditions such as collisions, compressions, and punctures, without affecting the normal operation of the battery. Summary of the Invention

[0006] This application provides an electrochemical device and electronic device that can improve the intermittent cycle performance of electrochemical devices under high temperature and high pressure, and effectively improve the safety performance under high voltage, thereby solving to some extent the problems existing in the prior art.

[0007] In one embodiment, this application provides an electrochemical device comprising: a positive electrode, a negative electrode, and an electrolyte. The positive electrode includes a positive electrode current collector and a positive electrode active material region, an insulating region, and an interaction region located on the positive electrode current collector. The interaction region is located between and in contact with the positive electrode active material region and the insulating region. The positive electrode active material region includes a positive electrode active material. The insulating region includes an inorganic filler. The interaction region includes the positive electrode active material and the inorganic filler. The electrolyte includes at least one of a compound having a cyano group or a compound having a sulfur-oxygen double bond.

[0008] In some embodiments, the electrolyte comprises a compound having a cyano group and a compound having a sulfur-oxygen double bond, wherein, based on the mass of the electrolyte, the mass percentage of the compound having the cyano group is a%, and the mass percentage of the compound having the sulfur-oxygen double bond is b%, wherein a and b satisfy: 0.1 ≤ a + b ≤ 15; and 0.5 ≤ a / b ≤ 20.

[0009] In some embodiments, the mass of the positive electrode active material region is A1 mg / 1540.25 mm. 2 The mass of the insulating region is A2 mg / 1540.25mm. 2 A1 and A2 satisfy: A1 / A2>1.2.

[0010] In some embodiments, the mass of the positive electrode active material region is A1 mg / 1540.25 mm. 2 The value of A1 ranges from 100 to 400.

[0011] In some embodiments, based on the mass of the insulating region, the mass percentage of inorganic filler in the insulating region is M1%, and the mass of the insulating region is A2 g / 1540.25mm. 2 M1 and A2 satisfy: 0.3≤M1 / A2≤1.5.

[0012] In some embodiments, the mass of the positive electrode active material region is A1 mg / 1540.25 mm. 2 The mass percentage of the compound with cyano groups is a% based on the mass of the electrolyte, wherein A1 and a satisfy: A1 / a > 8.

[0013] In some embodiments, the inorganic filler includes at least one of silicon dioxide, alumina, hydrated alumina, titanium dioxide, magnesium oxide, magnesium hydroxide, alumina-doped silicon dioxide, or boehmite.

[0014] In some embodiments, the cyano-containing compound includes at least one of the following compounds: succinate, glutaronitrile, adiponitrile, 1,5-dicyanopentane, 1,6-dicyanohexane, tetramethylsuccinate, 2-methylglutaronitrile, 2,4-dimethylglutaronitrile, 2,2,4,4-tetramethylglutaronitrile, 1,4-dicyanopentane, 1,2-dicyanobenzene, 1,3-dicyanobenzene, 1,4-dicyanobenzene, ethylene glycol bis(propionitrile) ether, and 3,5-dioxa-heptadionitrile. 1,4-Di(cyanoethoxy)butane, diethylene glycol di(2-cyanoethyl) ether, triethylene glycol di(2-cyanoethyl) ether, tetraethylene glycol di(2-cyanoethyl) ether, 1,3-Di(2-cyanoethoxy)propane, 1,4-Di(2-cyanoethoxy)butane, 1,5-Di(2-cyanoethoxy)pentane, ethylene glycol di(4-cyanobutyl) ether, 1,4-dicyano-2-butene, 1,4-dicyano-2-methyl-2-butene, 1,4-dicyano-2-butene, 1,4-Dicyano-2,3-dimethyl-2-butene, 1,4-dicyano-2,3-diethyl-2-butene, 1,6-dicyano-3-hexene, 1,6-dicyano-2-methyl-3-hexene, 1,3,5-pentanetricarbonyl, 1,2,3-propanetricarbonyl, 1,3,6-hexanetricarbonyl, 1,2,6-hexanetricarbonyl, 1,2,3-tris(2-cyanoethoxy)propane, 1,2,4-tris(2-cyanoethoxy)propane The electrolyte contains butane, 1,1,1-tris(cyanoethoxymethylene)ethane, 1,1,1-tris(cyanoethoxymethylene)propane, 3-methyl-1,3,5-tris(cyanoethoxy)pentane, 1,2,7-tris(cyanoethoxy)heptane, 1,2,6-tris(cyanoethoxy)hexane, or 1,2,5-tris(cyanoethoxy)pentane; wherein, based on the mass of the electrolyte, the mass percentage of the compound containing the cyano group is a%, and the value of a ranges from 0.1 to 15%.

[0015] In some embodiments, the cyano group-containing compound comprises at least two dinitrile compounds.

[0016] In some embodiments, the cyano group-containing compounds include dinitrile compounds and trinitrile compounds.

[0017] In some embodiments, the cyano compound includes a dinitrile compound having an ether bond or a trinitrile compound having an ether bond.

[0018] In some embodiments, the compound having a sulfur-oxygen double bond includes at least one of the following compounds: bicyclic sulfate, bicyclic sulfonyl lactone, vinyl sulfate, propylene sulfate, 1,3-propanesulfonyl lactone, 1,3-propenesulfonyl lactone, methanedisulfonate, or ethylene methanedisulfonate; wherein the mass percentage of the compound having a sulfur-oxygen double bond is b% based on the mass of the electrolyte, and b ranges from 0.001 to 8.

[0019] In some embodiments, the compound having a sulfur-oxygen double bond includes compounds of formula 1: ;

[0020] in,

[0021] W selected , , or ;

[0022] Each instance of L is independently selected from a single bond or a methylene group; m is 1, 2, 3, or 4;

[0023] n is 0, 1, or 2; and p is 0, 1, 2, 3, 4, 5, or 6.

[0024] In some embodiments, the compound of formula 1 includes at least one of the following compounds: or .

[0025] In some embodiments, the compound of formula 1 includes at least one of the following compounds: , , , or .

[0026] In some embodiments, the bicyclic sulfonyl lactone comprises a compound of formula 2: ;

[0027] Among them, A1, A2, A3, and A4 are each independently selected from substituted or unsubstituted alkylene groups.

[0028] When A1, A2, A3, and A4 are substituted independently, the substituents are selected from halogens, alkyl groups, or halogen-substituted alkyl groups.

[0029] In some embodiments, the compound of formula 2 includes at least one of the following compounds: , , , , , , or .

[0030] In some embodiments, the positive electrode active material region comprises a polyol.

[0031] In some embodiments, the polyol comprises at least one of the following compounds: methyl glycol, ethylene glycol, propylene glycol, isopentyl glycol, 1,3-butanediol, 1,4-butanediol, diethylene glycol, dipropylene glycol, polyethylene glycol, polypropylene glycol, glycerol, diglycerol, or polyglycerol.

[0032] In another embodiment, this application provides an electronic device that includes the electrochemical device described in the embodiments of this application.

[0033] The electrochemical device provided in this application has improved intermittent cycling performance and safety performance under high temperature and high pressure.

[0034] Additional aspects and advantages of the embodiments of this application will be described and shown in part in the following description, or illustrated by practice of the embodiments of this application. Attached Figure Description

[0035] Figure 1 An image of the positive electrode surface in one embodiment of this application is shown.

[0036] Figure 2 A schematic diagram of the structure of the positive electrode surface in a comparative example of this application is shown.

[0037] Figure 3 A schematic diagram of the structure of the positive electrode surface in one embodiment of this application is shown.

[0038] Figure 4 A schematic diagram of the structure of the positive electrode surface in one embodiment of this application is shown. Detailed Implementation

[0039] The embodiments of this application will be described in detail below. These embodiments should not be construed as limiting the scope of this application.

[0040] Additionally, quantities, ratios, and other numerical values ​​are sometimes presented in range format in this document. It should be understood that such range format is for convenience and brevity and should be interpreted flexibly to include not only the numerical values ​​explicitly specified as range limits, but also all individual numerical values ​​or subranges covered within the range, as if each numerical value and subrange were explicitly specified.

[0041] In the detailed description and claims, a list of items connected by the terms "one of," "among," "a kind of," or other similar terms may mean any of the listed items. For example, if items A and B are listed, the phrase "one of A and B" means only A or only B. In another example, if items A, B, and C are listed, the phrase "one of A, B, and C" means only A; only B; or only C. Item A may contain a single element or multiple elements. Item B may contain a single element or multiple elements. Item C may contain a single element or multiple elements.

[0042] In the detailed description and claims, a list of items connected by the terms "at least one of," "at least one of," "at least one of," or other similar terms may mean any combination of the listed items. For example, if items A and B are listed, then the phrase "at least one of A and B" means only A; only B; or A and B. In another example, if items A, B, and C are listed, then the phrase "at least one of A, B, and C" means only A; or only B; only C; A and B (excluding C); A and C (excluding B); B and C (excluding A); or all of A, B, and C. Item A may contain a single element or multiple elements. Item B may contain a single element or multiple elements. Item C may contain a single element or multiple elements.

[0043] I. Electrochemical Device

[0044] In some embodiments, this application provides an electrochemical device, which includes a positive electrode, a negative electrode, and an electrolyte.

[0045] I. Positive electrode

[0046] In some embodiments, the positive electrode includes a positive current collector and a positive active material region located on one or both surfaces of the positive current collector.

[0047] In some embodiments, the positive electrode active material region comprises a positive electrode active material. The positive electrode active material region may be one or more layers, and each layer in a multi-layer positive electrode active material region may contain the same or different positive electrode active materials. The positive electrode active material is any material capable of reversibly inserting and deintercalating metal ions such as lithium ions. In some embodiments, the discharge capacity of the positive electrode active material is less than its rechargeable capacity to prevent unintentional deposition of lithium metal onto the negative electrode during charging.

[0048] In some embodiments, the positive current collector has a current collector exposed portion where no positive active material region is formed. The positive current collector exposed portion is formed such that it extends outward from one end in the winding axis direction of the winding electrode body (i.e., the sheet width direction orthogonal to the aforementioned length direction). The positive current collector exposed portion is engaged with the positive current collector.

[0049] In some embodiments, the positive electrode has an insulating region formed on the positive electrode current collector and an interaction region formed on the positive electrode current collector. In some embodiments, the insulating region is disposed along the end of the positive electrode active material region on the exposed side of the positive electrode current collector, and the insulating region extends along the length direction of the positive electrode. In some embodiments, the insulating region is located between the positive electrode active material region and the exposed positive electrode current collector in the width direction of the positive electrode. In some embodiments, the exposed positive electrode current collector is covered by the insulating region.

[0050] In some embodiments, the interaction region is located at the boundary between the insulating region and the positive electrode active material region, and the interaction region extends along the length direction of the positive electrode. Therefore, the interaction region is located between the positive electrode active material region and the insulating region. Furthermore, the interaction region is in contact with both the positive electrode active material region and the insulating region.

[0051] Figure 1 An image of the positive electrode surface in one embodiment of this application is shown. Figure 1 It can be seen that the interaction region is located between the positive electrode active material region and the insulating region, and extends along the length of the positive electrode.

[0052] Figure 2 A schematic diagram of the positive electrode surface in a comparative example of this application is shown, where 200 is the positive electrode surface, 210 is the positive electrode active material region located on the positive electrode current collector, and 220 is the exposed portion of the positive electrode current collector. In this embodiment, the exposed portion of the positive electrode current collector is not covered.

[0053] Figure 3 A schematic diagram of the positive electrode surface in one embodiment of this application is shown, wherein 300 is the positive electrode surface, 310 is the positive electrode active material region located on the positive electrode current collector, 320 is the interaction region located on the positive electrode current collector, and 330 is the insulating region located on the positive electrode current collector. In this embodiment, the interaction region is located between the positive electrode active material region and the insulating region, and is in contact with both the positive electrode active material region and the insulating region, and the current collector is completely covered.

[0054] Figure 4 A schematic diagram of the positive electrode surface in one embodiment of this application is shown, wherein 400 is the positive electrode surface, 410 is the positive electrode active material region located on the positive electrode current collector, 420 is the interaction region located on the positive electrode current collector, 430 is the insulating region located on the positive electrode current collector, and 440 is the exposed portion of the positive electrode current collector. In this embodiment, the exposed portion of the positive electrode current collector is not completely covered.

[0055] In some embodiments, the mass of the positive electrode active material region is A1 mg / 1540.25 mm. 2The mass of the insulating region is A2mg / 1540.25mm. 2 A1 and A2 satisfy: A1 / A2>1.2.

[0056] In some embodiments, A1 / A2≥2, A1 / A2≥2.5, A1 / A2≥3, A1 / A2≥4, or A1 / A2≥5.

[0057] In some embodiments, the mass of the positive electrode active material region is A1 mg / 1540.25 mm. 2 The value of A1 ranges from 100 to 400. In some embodiments, the value of A1 is 100, 120, 140, 150, 160, 180, 200, 220, 240, 250, 280, 300, 330, 350, 380, 400, or a range of any two of these values.

[0058] In some embodiments, the mass of the insulating region is A2mg / 1540.25mm. 2 The value of A2 is between 60 and 250. In some embodiments, the value of A2 is 60, 70, 80, 100, 120, 140, 150, 160, 180, 200, 220, 230, 240, 250 or a range of any two of these values.

[0059] In some embodiments, based on the mass of the insulating region, the mass percentage of inorganic filler in the insulating region is M1%, and the mass of the insulating region is A2 g / 1540.25mm. 2 M1 and A2 satisfy: 0.3≤M1 / A2≤1.5.

[0060] In some embodiments, 0.6 ≤ M1 / A2 ≤ 1.5. In some embodiments, the value of M1 / A2 is 0.3, 0.5, 0.6, 0.7, 0.9, 1.2, 1.4, 1.5 or a range of any two of these values.

[0061] In some embodiments, the value of M1 ranges from 80 to 95. In some embodiments, the value of M1 ranges from 85 to 95. In some embodiments, the value of M1 is 80, 82, 85, 88, 90, 92, 95, or a range of any two of these values.

[0062] In some embodiments, the insulating region is located on both sides of the positive current collector, or on one side. In some embodiments, the interaction region is located on both sides of the positive current collector, or on one side.

[0063] In some embodiments, the inorganic filler includes at least one of silicon dioxide, alumina, hydrated alumina, titanium dioxide, magnesium oxide, magnesium hydroxide, alumina-doped silicon dioxide, or boehmite.

[0064] In some embodiments, the inorganic filler may be in the form of particles, fibers, plates, flakes, etc. In some embodiments, the average particle size of the inorganic filler is 0.01 μm or more and 10 μm or less, preferably 0.1 μm or more and 5 μm or less, more preferably 0.5 μm or more and 3 μm or less. In some embodiments, the average particle size (median particle size D50) of the inorganic filler may be measured, for example, by laser diffraction scattering.

[0065] In some embodiments, the inorganic filler is an insulating inorganic particle. Examples of the inorganic particles in some embodiments include, but are not limited to, inorganic oxides (e.g., alumina, magnesium oxide, silicon dioxide, titanium dioxide, etc.), nitrides (e.g., aluminum nitride, silicon nitride, etc.), alumina hydrates, metal hydroxides other than alumina hydrates (e.g., potassium hydroxide, magnesium hydroxide, etc.), clay minerals (e.g., mica, talc, zeolite, apatite, kaolin, etc.), glass fibers, etc. They can be used alone or in combination of two or more.

[0066] In some embodiments, the insulating region may contain an adhesive. In some embodiments, the adhesive includes, but is not limited to, acrylic adhesives, styrene-butadiene rubber (SBR), polyolefin adhesives, etc., and fluoropolymers such as polyvinylidene fluoride (PVDF) and polytetrafluoroethylene (PTFE) may also be used.

[0067] In some embodiments, there is no particular limitation on the adhesive content in the insulating region. For example, based on the mass of the insulating region, the adhesive content is 1% or more and 30% or less, preferably 3% or more and 25% or less. In some embodiments, the adhesive content is a range of 1%, 5%, 10%, 15%, 20%, 25%, 30%, or any combination of these values.

[0068] In some embodiments, the interaction region contains at least: the positive electrode active material contained in the positive electrode active material region; and the inorganic filler contained in the insulating region.

[0069] In some embodiments, the interaction region is a layer formed by mixing the aforementioned components of the positive electrode active material region and the aforementioned components of the insulating region. Therefore, the interaction region may contain components of the positive electrode active material region and / or components of the insulating region, other than the aforementioned positive electrode active material and inorganic filler. For example, the interaction region may further contain an adhesive from the positive electrode active material region and / or the insulating region.

[0070] In some embodiments, where the positive electrode active material region contains a positive electrode active material, a conductive material, and an adhesive, and the insulating region contains an inorganic filler and an adhesive, the interaction region contains a positive electrode active material, a conductive material, an adhesive for the positive electrode active material region, an inorganic filler, and an adhesive for the insulating region.

[0071] In some embodiments, the interaction region contains alumina hydrate. In one embodiment where the interaction region contains alumina hydrate, in addition to the aforementioned positive electrode active material and inorganic filler, the interaction region also contains alumina hydrate. In another embodiment where the interaction region contains alumina hydrate, in addition to the aforementioned positive electrode active material and inorganic filler, the inorganic filler is alumina hydrate.

[0072] In some embodiments, the alumina hydrate contains hydroxyl groups. In some embodiments, the alumina hydrate includes, but is not limited to, aluminum hydroxide (AlOOH) as a crystalline alumina monohydrate; aluminum hydroxide (Al(OH)3) as a crystalline alumina trihydrate; and alumina gel as an amorphous alumina hydrate. In some embodiments, the crystalline alumina hydrate (i.e., crystalline alumina monohydrate and crystalline alumina trihydrate) can be either α-type or β-type, preferably α-type. In some embodiments, the alumina hydrate is preferably aluminum hydroxide, such as boehmite, which can further improve safety performance.

[0073] In some embodiments, the average particle size (median particle size D50) of the alumina hydrate is not particularly limited. When the average particle size of the alumina hydrate is too small, it becomes easier for acids (especially HF) to form in the electrolyte, potentially leading to deterioration of the positive electrode active material. Therefore, the average particle size of the alumina hydrate is preferably 0.5 μm or more. On the other hand, when the average particle size of the alumina hydrate is too large, it becomes difficult for acids (especially HF) to form in the electrolyte, affecting intermittent cycling performance. Therefore, the average particle size of the alumina hydrate is preferably 3 μm or less. The average particle size (median particle size D50) of the alumina hydrate can be determined, for example, by laser diffraction scattering.

[0074] In some embodiments, the interaction region can be formed by simultaneously or sequentially applying a paste forming the positive electrode active material region and a paste forming the insulating region onto a positive electrode current collector in an adjacent manner, and then simultaneously drying these pastes. During this process, before drying, the paste forming the positive electrode active material region and the paste forming the insulating region mix at the interface, thus forming an interaction region at the interface between the positive electrode active material region and the insulating region. By selecting alumina hydrate as the inorganic filler in the paste forming the insulating region, the interaction region can contain alumina hydrate; alternatively, the paste forming the positive electrode active material region, the paste forming the insulating region, and the alumina hydrate-containing paste forming the interaction region can be used to form the positive electrode active material region, the insulating region, and the interaction region.

[0075] In some embodiments, the positive electrode active material region further comprises a polyol. In some embodiments, the polyol comprises at least one of the following compounds: methyl glycol, ethylene glycol, propylene glycol, isopentyl glycol, 1,3-butanediol, 1,4-butanediol, diethylene glycol, dipropylene glycol, polyethylene glycol, polypropylene glycol, glycerol, diglycerol, or polyglycerol.

[0076] In some embodiments, the content of the polyol is no more than 0.3% based on the total weight of the positive electrode active material region. In some embodiments, the content of the polyol is 0.01%, 0.05%, 0.1%, 0.12%, 0.15%, 0.18%, 0.2%, 0.25%, 0.28%, 0.3%, or a range of any two of these values, based on the total weight of the positive electrode active material region.

[0077] In some embodiments, the type of positive electrode active material is not particularly limited, as long as it is capable of electrochemically adsorbing and releasing metal ions (e.g., lithium ions). In some embodiments, the positive electrode active material is a substance containing lithium and at least one transition metal. Examples of positive electrode active materials may include, but are not limited to, lithium transition metal composite oxides and lithium transition metal phosphate compounds.

[0078] In some embodiments, the transition metal in the lithium transition metal composite oxide includes V, Ti, Cr, Mn, Fe, Co, Ni, Cu, etc. In some embodiments, the lithium transition metal composite oxide includes lithium cobalt composite oxides such as LiCoO2, lithium nickel composite oxides such as LiNiO2, lithium manganese composite oxides such as LiMnO2, LiMn2O4, and Li2MnO4, and LiNi... 1 / 3 Mn 1 / 3 Co 1 / 3 O2, LiNi 0.5 Mn 0.3 Co 0.2Lithium-nickel-manganese-cobalt composite oxides, such as O2, in which a portion of the transition metal atoms that form the bulk of these lithium transition metal composite oxides are replaced by other elements such as Na, K, B, F, Al, Ti, V, Cr, Mn, Fe, Co, Li, Ni, Cu, Zn, Mg, Ga, Zr, Si, Nb, Mo, Sn, and W. Examples of lithium transition metal composite oxides include, but are not limited to, LiNi. 0.5 Mn 0.5 O2, LiNi 0.85 Co 0.10 Al 0.05 O2, LiNi 0.33 Co 0.33 Mn 0.33 O2, LiNi 0.45 Co 0.10 Al 0.45 O2, LiMn 1.8 Al 0.2 O4 and LiMn 1.5 Ni 0.5 O4, etc. Examples of combinations of lithium transition metal composite oxides include, but are not limited to, combinations of LiCoO2 and LiMn2O4, wherein a portion of the Mn in LiMn2O4 can be replaced by a transition metal (e.g., LiNi). 0.33 Co 0.33 Mn 0.33 In LiCoO2, some of the Co can be replaced by transition metals.

[0079] In some embodiments, the transition metal in the lithium transition metal phosphate compound includes V, Ti, Cr, Mn, Fe, Co, Ni, Cu, etc. In some embodiments, the lithium transition metal phosphate compound includes iron phosphates such as LiFePO4, Li3Fe2(PO4)3, and LiFeP2O7, and cobalt phosphates such as LiCoPO4, wherein a portion of the transition metal atoms that constitute the main body of these lithium transition metal phosphate compounds are replaced by other elements such as Al, Ti, V, Cr, Mn, Fe, Co, Li, Ni, Cu, Zn, Mg, Ga, Zr, Nb, Si, etc.

[0080] In some embodiments, the positive electrode active material includes lithium phosphate, which can improve the continuous charging characteristics of the electrochemical device. The use of lithium phosphate is not limited. In some embodiments, the positive electrode active material and lithium phosphate are used in combination. In some embodiments, the content of lithium phosphate relative to the weight of the positive electrode active material and lithium phosphate is greater than 0.1%, greater than 0.3%, or greater than 0.5%. In some embodiments, the content of lithium phosphate relative to the weight of the positive electrode active material and lithium phosphate is less than 10%, less than 8%, or less than 5%. In some embodiments, the content of lithium phosphate is within the range of any two of the above values.

[0081] In some embodiments, a substance with a different composition may be attached to the surface of the above-mentioned positive electrode active material. Examples of the surface-attached substance may include, but are not limited to: oxides such as aluminum oxide, silicon dioxide, titanium dioxide, zirconium oxide, magnesium oxide, calcium oxide, boron oxide, antimony oxide, and bismuth oxide; sulfates such as lithium sulfate, sodium sulfate, potassium sulfate, magnesium sulfate, calcium sulfate, and aluminum sulfate; carbonates such as lithium carbonate, calcium carbonate, and magnesium carbonate; and carbon, etc.

[0082] In some embodiments, these surface-adhesive substances can be attached to the surface of the positive electrode active material by methods such as: dissolving or suspending the surface-adhesive substance in a solvent and adding it into the positive electrode active material followed by drying; dissolving or suspending a surface-adhesive substance precursor in a solvent, adding it into the positive electrode active material, and then reacting it by heating or the like; and adding it to the positive electrode active material precursor while simultaneously calcining, etc. In the case of carbon attachment, a method of mechanically attaching carbon materials (e.g., activated carbon, etc.) can also be used.

[0083] In some embodiments, the content of surface-attached material, based on the weight of the positive electrode active material region, is greater than 0.1 ppm, greater than 1 ppm, or greater than 10 ppm. In some embodiments, the content of surface-attached material, based on the weight of the positive electrode active material region, is less than 10%, less than 5%, or less than 2%. In some embodiments, the content of surface-attached material, based on the weight of the positive electrode active material region, is within the range of any two of the above values.

[0084] By attaching a substance to the surface of the positive electrode active material, the oxidation reaction of the electrolyte on the surface of the positive electrode active material can be suppressed, thereby improving the lifespan of the electrochemical device. When the amount of surface-attached substance is too small, its effect cannot be fully realized; when the amount of surface-attached substance is too large, it will hinder the entry and exit of lithium ions, thus sometimes increasing the resistance.

[0085] In this application, a positive electrode active material on which a substance with a different composition is attached to the surface of the positive electrode active material is also referred to as a "positive electrode active material".

[0086] In some embodiments, the shape of the positive electrode active material includes, but is not limited to, blocky, polyhedral, spherical, ellipsoidal, plate-like, needle-like, and columnar shapes. In some embodiments, the positive electrode active material particles include primary particles, secondary particles, or combinations thereof. In some embodiments, primary particles may aggregate to form secondary particles.

[0087] In some embodiments, the tap density of the positive electrode active material is greater than 0.5 g / cm³. 3 Greater than 0.8 g / cm 3 or greater than 1.0 g / cm³ 3 When the tap density of the positive electrode active material is within the above-mentioned range, the amount of dispersion medium required for the formation of the positive electrode active material region, as well as the required amounts of conductive material and positive electrode binder, can be suppressed, thereby ensuring the filling rate of the positive electrode active material and the capacity of the electrochemical device. A high-density positive electrode active material region can be formed by using composite oxide powder with high tap density. Generally, a higher tap density is preferred, with no particular upper limit. In some embodiments, the tap density of the positive electrode active material is less than 4.0 g / cm³. 3 Less than 3.7 g / cm 3 or less than 3.5g / cm 3 When the tap density of the positive electrode active material has the upper limit mentioned above, the reduction in load characteristics can be suppressed.

[0088] The tap density of the positive electrode active material can be calculated as follows: Place 5g to 10g of positive electrode active material powder into a 10mL glass graduated cylinder and vibrate it 200 times with a stroke of 20mm to obtain the powder filling density (tap density).

[0089] When the positive electrode active material particles are primary particles, the median particle size (D50) refers to the primary particle size. When the primary particles of the positive electrode active material aggregate to form secondary particles, the median particle size (D50) refers to the secondary particle size.

[0090] In some embodiments, the median particle size (D50) of the positive electrode active material particles is greater than 0.3 μm, greater than 0.5 μm, greater than 0.8 μm, or greater than 1.0 μm. In some embodiments, the median particle size (D50) of the positive electrode active material particles is less than 30 μm, less than 27 μm, less than 25 μm, or less than 22 μm. In some embodiments, the median particle size (D50) of the positive electrode active material particles is within the range of any two of the above values. When the median particle size (D50) of the positive electrode active material particles is within the above range, a positive electrode active material with high tap density can be obtained, which can suppress the degradation of the performance of the electrochemical device. On the other hand, during the preparation process of the positive electrode of the electrochemical device (i.e., when the positive electrode active material, conductive material, and binder are slurried with a solvent and coated in a thin film), problems such as streaking can be prevented. Here, by mixing two or more positive electrode active materials with different median particle sizes, the filling properties during positive electrode preparation can be further improved.

[0091] The median particle size (D50) of the positive electrode active material particles can be determined using a laser diffraction / scattering particle size distribution measuring device: using a HORIBA LA-920 as the particle size distributor, a 0.1% sodium hexametaphosphate aqueous solution is used as the dispersion medium for the measurement. After ultrasonic dispersion for 5 minutes, the refractive index is set to 1.24 for measurement.

[0092] II. Electrolyte

[0093] The electrolyte used in the electrochemical device of this application includes an electrolyte and a solvent for dissolving the electrolyte. In some embodiments, the electrolyte used in the electrochemical device of this application further includes additives.

[0094] In some embodiments, the electrolyte comprises at least one of a compound having a cyano group or a compound having a sulfur-oxygen double bond.

[0095] In some embodiments, the cyano-containing compound includes at least one of the following compounds: succinic anionyl, glutaronitrile, adiponitrile, 1,5-dicyanopentane, 1,6-dicyanohexane, tetramethylsuccinic anionyl, 2-methylglutaronitrile, 2,4-dimethylglutaronitrile, 2,2,4,4-tetramethylglutaronitrile, 1,4-dicyanopentane, 1,2-dicyanobenzene, 1,3-dicyanobenzene, 1,4-dicyanobenzene, and ethylene glycol bis(propionitrile) ether. 3,5-Dioxa-heptadionitrile, 1,4-Di(cyanoethoxy)butane, diethylene glycol di(2-cyanoethyl) ether, triethylene glycol di(2-cyanoethyl) ether, tetraethylene glycol di(2-cyanoethyl) ether, 1,3-Di(2-cyanoethoxy)propane, 1,4-Di(2-cyanoethoxy)butane, 1,5-Di(2-cyanoethoxy)pentane, ethylene glycol di(4-cyanobutyl) ether, 1,4-dicyano-2-butene, 1 4-Dicyano-2-methyl-2-butene, 1,4-dicyano-2-ethyl-2-butene, 1,4-dicyano-2,3-dimethyl-2-butene, 1,4-dicyano-2,3-diethyl-2-butene, 1,6-dicyano-3-hexene, 1,6-dicyano-2-methyl-3-hexene, 1,3,5-pentanetricarbonyl, 1,2,3-propanetricarbonyl, 1,3,6-hexanetricarbonyl, 1,2,6-hexanetricarbonyl 1,2,3-tris(2-cyanoethoxy)propane, 1,2,4-tris(2-cyanoethoxy)butane, 1,1,1-tris(cyanoethoxymethylene)ethane, 1,1,1-tris(cyanoethoxymethylene)propane, 3-methyl-1,3,5-tris(cyanoethoxy)pentane, 1,2,7-tris(cyanoethoxy)heptane, 1,2,6-tris(cyanoethoxy)hexane, or 1,2,5-tris(cyanoethoxy)pentane.

[0096] The aforementioned compounds containing cyano groups can be used alone or in any combination. If the electrolyte contains two or more compounds containing cyano groups, the content of the cyano-containing compounds refers to the total content of the two or more cyano-containing compounds.

[0097] In some embodiments, the mass percentage of the cyano-containing compound is a%, based on the mass of the electrolyte, and the value of a ranges from 0.1 to 15. In some embodiments, the value of a is 0.1, 0.4, 0.8, 1, 1.6, 2.0, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, or a range of any two of these values.

[0098] In some embodiments, the cyano-containing compound comprises at least two dinitrile compounds. In some embodiments, the cyano-containing compound comprises a dinitrile compound and a trinitrile compound. In some embodiments, the cyano-containing compound comprises a dinitrile compound having an ether bond or a trinitrile compound having an ether bond.

[0099] In some embodiments, A1 and a satisfy: A1 / a > 8. In some embodiments, A1 and a satisfy: A1 / a ≥ 10. In some embodiments, A1 and a satisfy: A1 / a ≥ 15. In some embodiments, A1 and a satisfy: A1 / a ≥ 20. In some embodiments, A1 and a satisfy: A1 / a ≥ 30. In some embodiments, A1 and a satisfy: A1 / a ≥ 40. In some embodiments, the value of A1 / a is 8, 10, 12, 15, 18, 20, 22, 25, 28, 30, 32, 35, 38, 40, 42, 45, or a range of any two of these values.

[0100] In some embodiments, the compound having a sulfur-oxygen double bond includes at least one of the following compounds: bicyclic sulfate, bicyclic sulfonyl lactone, vinyl sulfate, propylene sulfate, 1,3-propanesulfonyl lactone, 1,3-propenesulfonyl lactone, methylene disulfonate, or ethylene disulfonate.

[0101] In some embodiments, the compound having a sulfur-oxygen double bond includes compounds of formula 1: ;

[0102] in,

[0103] W selected , , or ;

[0104] Each instance of L is independently selected from a single bond or a methylene group; m is 1, 2, 3, or 4;

[0105] n is 0, 1, or 2; and p is 0, 1, 2, 3, 4, 5, or 6.

[0106] In some embodiments, the compound of formula 1 includes at least one of the following compounds: or .

[0107] In some embodiments, the compound of formula 1 includes at least one of the following compounds: , , , or .

[0108] In some embodiments, the bicyclic sulfonyl lactone comprises a compound of formula 2: ;

[0109] Among them, A1, A2, A3, and A4 are each independently selected from substituted or unsubstituted alkylene groups.

[0110] When A1, A2, A3, and A4 are substituted independently, the substituents are selected from halogens, alkyl groups, or halogen-substituted alkyl groups.

[0111] In some embodiments, the compound of formula 2 includes at least one of the following compounds: , , , , , , or .

[0112] In some embodiments, the mass percentage of the compound having a sulfur-oxygen double bond is b%, based on the mass of the electrolyte, and the value of b ranges from 0.001 to 8. In some embodiments, the value of b is 0.001, 0.1, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, or a range of any two of these values.

[0113] In some embodiments, the electrolyte comprises a compound having a cyano group and a compound having a sulfur-oxygen double bond, satisfying the relationships: 0.1 ≤ a + b ≤ 15; and 0.5 ≤ a / b ≤ 20. In some embodiments, 0.1 < a + b < 15; and 2 < a / b < 12. In some embodiments, a + b takes the value of 0.1, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, or any combination of these values. In some embodiments, a / b takes the value of 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, or any combination of these values.

[0114] In some embodiments, the electrolyte further comprises any non-aqueous solvent known in the art that can be used as a solvent for an electrolyte.

[0115] In some embodiments, the non-aqueous solvent includes, but is not limited to, one or more of the following: cyclic carbonates, chain carbonates, cyclic carboxylic esters, chain carboxylic esters, cyclic ethers, chain ethers, phosphorus-containing organic solvents, sulfur-containing organic solvents, and aromatic fluorine-containing solvents.

[0116] In some embodiments, examples of the cyclic carbonate may include, but are not limited to, one or more of the following: ethylene carbonate (EC), propylene carbonate (PC), and butylene carbonate. In some embodiments, the cyclic carbonate has 3-6 carbon atoms.

[0117] In some embodiments, examples of the chain carbonate may include, but are not limited to, one or more of the following: dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate (DEC), methyl n-propyl carbonate, ethyl n-propyl carbonate, di n-propyl carbonate, etc. Examples of fluorine-substituted chain carbonates may include, but are not limited to, one or more of the following: bis(fluoromethyl) carbonate, bis(difluoromethyl) carbonate, bis(trifluoromethyl) carbonate, bis(2-fluoroethyl) carbonate, bis(2,2-difluoroethyl) carbonate, bis(2,2,2-trifluoroethyl) carbonate, 2-fluoroethylmethyl carbonate, 2,2-difluoroethylmethyl carbonate, and 2,2,2-trifluoroethylmethyl carbonate, etc.

[0118] In some embodiments, examples of the cyclic carboxylic acid ester may include, but are not limited to, one or more of the following: γ-butyrolactone and γ-valerolactone. In some embodiments, some hydrogen atoms of the cyclic carboxylic acid ester may be substituted with fluorine.

[0119] In some embodiments, examples of the chain carboxylic acid ester may include, but are not limited to, one or more of the following: methyl acetate, ethyl acetate, propyl acetate, isopropyl acetate, butyl acetate, sec-butyl acetate, isobutyl acetate, tert-butyl acetate, methyl propionate, ethyl propionate, propyl propionate, isopropyl propionate, methyl butyrate, ethyl butyrate, propyl butyrate, methyl isobutyrate, ethyl isobutyrate, methyl valerate, ethyl valerate, methyl pivalate, and ethyl pivalate. In some embodiments, some hydrogen atoms of the chain carboxylic acid ester may be substituted with fluorine. In some embodiments, examples of fluorinated chain carboxylic acid esters may include, but are not limited to, methyl trifluoroacetate, ethyl trifluoroacetate, propyl trifluoroacetate, butyl trifluoroacetate, and 2,2,2-trifluoroethyl trifluoroacetate.

[0120] In some embodiments, examples of the cyclic ether may include, but are not limited to, one or more of the following: tetrahydrofuran, 2-methyltetrahydrofuran, 1,3-dioxolane, 2-methyl-1,3-dioxolane, 4-methyl-1,3-dioxolane, 1,3-dioxane, 1,4-dioxane, and dimethoxypropane.

[0121] In some embodiments, examples of the chain ether may include, but are not limited to, one or more of the following: dimethoxymethane, 1,1-dimethoxyethane, 1,2-dimethoxyethane, diethoxymethane, 1,1-diethoxyethane, 1,2-diethoxyethane, ethoxymethoxymethane, 1,1-ethoxymethoxyethane, and 1,2-ethoxymethoxyethane, etc.

[0122] In some embodiments, examples of the phosphorus-containing organic solvent may include, but are not limited to, one or more of the following: trimethyl phosphate, triethyl phosphate, dimethyl ethyl phosphate, methyl diethyl phosphate, ethylene phosphate, ethylene phosphate, triphenyl phosphate, trimethyl phosphite, triethyl phosphite, triphenyl phosphite, tri(2,2,2-trifluoroethyl) phosphate, and tri(2,2,3,3,3-pentafluoropropyl) phosphate, etc.

[0123] In some embodiments, examples of the sulfur-containing organic solvent may include, but are not limited to, one or more of the following: sulfolane, 2-methylsulfolane, 3-methylsulfolane, dimethyl sulfone, diethyl sulfone, ethyl methyl sulfone, methylpropyl sulfone, dimethyl sulfoxide, methyl methanesulfonate, ethyl methanesulfonate, methyl ethanesulfonate, ethyl ethanesulfonate, dimethyl sulfate, diethyl sulfate, and dibutyl sulfate. In some embodiments, some hydrogen atoms of the sulfur-containing organic solvent may be substituted with fluorine.

[0124] In some embodiments, the aromatic fluorinated solvent includes, but is not limited to, one or more of the following: fluorobenzene, difluorobenzene, trifluorobenzene, tetrafluorobenzene, pentafluorobenzene, hexafluorobenzene, and trifluoromethylbenzene.

[0125] In some embodiments, the solvent used in the electrolyte of this application includes cyclic carbonates, linear carbonates, cyclic carboxylic acid esters, linear carboxylic acid esters, and combinations thereof. In some embodiments, the solvent used in the electrolyte of this application comprises an organic solvent selected from the group consisting of: ethylene carbonate, propylene carbonate, diethyl carbonate, ethyl propionate, propyl propionate, n-propyl acetate, ethyl acetate, and combinations thereof. In some embodiments, the solvent used in the electrolyte of this application comprises: ethylene carbonate, propylene carbonate, diethyl carbonate, ethyl propionate, propyl propionate, γ-butyrolactone, and combinations thereof.

[0126] In some embodiments, the electrolyte is not particularly limited, and any substance known as an electrolyte can be used. In the case of lithium secondary batteries, lithium salts are typically used. Examples of electrolytes may include, but are not limited to, inorganic lithium salts such as LiPF6, LiBF4, LiClO4, LiAlF4, LiSbF6, and LiWF7; lithium tungstates such as LiWOF5; lithium carboxylate salts such as HCO2Li, CH3CO2Li, CH2FCO2Li, CHF2CO2Li, CF3CO2Li, CF3CH2CO2Li, CF3CF2CO2Li, CF3CF2CF2CO2Li, and CF3CF2CF2CF2CO2Li; and lithium carboxylate salts such as FSO3Li and CH3SO3Li. Lithium sulfonate salts such as CH2FSO3Li, CHF2SO3Li, CF3SO3Li, CF3CF2SO3Li, CF3CF2CF2SO3Li, and CF3CF2CF2CF2SO3Li; lithium sulfonate salts such as LiN(FCO)2, LiN(FCO)(FSO2), LiN(FSO2)2, LiN(FSO2)(CF3SO2), LiN(CF3SO2)2, LiN(C2F5SO2)2, cyclic 1,2-perfluoroethane disulfonylimide lithium, and cyclic 1,3-perfluoropropane disulfonylimide. Lithium, imide lithium salts such as LiN(CF3SO2)(C4F9SO2); methylated lithium salts such as LiC(FSO2)3, LiC(CF3SO2)3, and LiC(C2F5SO2)3; lithium malonate lithium salts such as bis(malonate)borate and difluoro(malonate)borate; lithium tri(malonate)phosphate, lithium difluorobis(malonate)phosphate, and lithium tetrafluoro(malonate)phosphate; and lithium malonate phosphates such as LiPF4(CF3)2 and LiPF4(C2F5)2. Fluorine-containing organic lithium salts such as LiPF4(CF3SO2)2, LiPF4(C2F5SO2)2, LiBF3CF3, LiBF3C2F5, LiBF3C3F7, LiBF2(CF3)2, LiBF2(C2F5)2, LiBF2(CF3SO2)2, and LiBF2(C2F5SO2)2; lithium oxalate borate salts such as lithium difluorooxalate borate and lithium bis(oxalate) borate; and lithium oxalate phosphate salts such as lithium tetrafluorooxalate phosphate, lithium difluorobis(oxalate) phosphate, and lithium tri(oxalate) phosphate.

[0127] In some embodiments, the electrolyte is selected from LiPF6, LiSbF6, FSO3Li, CF3SO3Li, LiN(FSO2)2, LiN(FSO2)(CF3SO2), LiN(CF3SO2)2, LiN(C2F5SO2)2, cyclic 1,2-perfluoroethane disulfonylimide lithium, cyclic 1,3-perfluoropropane disulfonylimide lithium, LiC(FSO2)3, LiC(CF3SO2)3, LiC(C2F5SO2)3, LiBF3CF3, LiBF3C2F5, LiPF3(CF3)3, LiPF3(C2F5)3, lithium difluorooxalate borate, lithium bis(oxalate)borate, or lithium difluorobis(oxalate)phosphate, which helps to improve the output power characteristics, high-rate charge-discharge characteristics, high-temperature storage characteristics, and cycle characteristics of the electrochemical device.

[0128] There are no particular limitations on the content of the electrolyte, as long as it does not impair the effectiveness of this application. In some embodiments, the total molar concentration of lithium in the electrolyte is greater than 0.3 mol / L, greater than 0.4 mol / L, or greater than 0.5 mol / L. In some embodiments, the total molar concentration of lithium in the electrolyte is less than 3 mol / L, less than 2.5 mol / L, or less than 2.0 mol / L. In some embodiments, the total molar concentration of lithium in the electrolyte is within the range of any two of the above values. When the electrolyte concentration is within the above range, the amount of lithium as charged particles will not be too low, and the viscosity can be kept within an appropriate range, thus easily ensuring good conductivity.

[0129] When using two or more electrolytes, the electrolyte comprises at least one salt selected from the group consisting of monofluorophosphate, borate, oxalate, and fluorosulfonate. In some embodiments, the electrolyte comprises a salt selected from the group consisting of monofluorophosphate, oxalate, and fluorosulfonate. In some embodiments, the electrolyte comprises a lithium salt. In some embodiments, the content of a salt selected from the group consisting of monofluorophosphate, borate, oxalate, and fluorosulfonate is greater than 0.01% or greater than 0.1% based on the weight of the electrolyte. In some embodiments, the content of a salt selected from the group consisting of monofluorophosphate, borate, oxalate, and fluorosulfonate is less than 20% or less than 10% based on the weight of the electrolyte. In some embodiments, the content of a salt selected from the group consisting of monofluorophosphate, borate, oxalate, and fluorosulfonate is within the range of any two of the above values.

[0130] In some embodiments, the electrolyte comprises one or more substances selected from the group consisting of monofluorophosphates, borates, oxalates, and fluorosulfonates, and one or more other salts. Examples of other salts include lithium salts exemplified above, and in some embodiments, LiPF6, LiN(FSO2)(CF3SO2), LiN(CF3SO2)2, LiN(C2F5SO2)2, cyclic 1,2-perfluoroethane disulfonylimide lithium, cyclic 1,3-perfluoropropane disulfonylimide lithium, LiC(FSO2)3, LiC(CF3SO2)3, LiC(C2F5SO2)3, LiBF3CF3, LiBF3C2F5, LiPF3(CF3)3, and LiPF3(C2F5)3. In some embodiments, the other salt is LiPF6.

[0131] In some embodiments, the content of other salts, based on the weight of the electrolyte, is greater than 0.01% or greater than 0.1%. In some embodiments, the content of other salts, based on the weight of the electrolyte, is less than 20%, less than 15%, or less than 10%. In some embodiments, the content of other salts is within the range of any two of the above values. The presence of other salts at the above-mentioned levels helps to balance the conductivity and viscosity of the electrolyte.

[0132] III. Negative electrode

[0133] The negative electrode includes a negative electrode current collector and negative electrode active material regions disposed on one or both surfaces of the negative electrode current collector, wherein the negative electrode active material layer contains negative electrode active material. The negative electrode active material layer can be one or more layers, and each layer in a multilayer negative electrode active material layer can contain the same or different negative electrode active materials. The negative electrode active material is any material capable of reversibly inserting and deintercalating metal ions such as lithium ions. In some embodiments, the rechargeable capacity of the negative electrode active material is greater than the discharge capacity of the positive electrode active material to prevent unintentional deposition of lithium metal on the negative electrode during charging.

[0134] As the current collector for retaining the active material of the negative electrode, any known current collector can be used. Examples of negative electrode current collectors include, but are not limited to, metallic materials such as aluminum, copper, nickel, stainless steel, and nickel-plated steel. In some embodiments, the negative electrode current collector is copper.

[0135] When the negative electrode current collector is a metallic material, its form may include, but is not limited to, metal foil, metal cylinder, metal strip roll, metal plate, metal film, metal mesh, stamped metal, foamed metal, etc. In some embodiments, the negative electrode current collector is a metal film. In some embodiments, the negative electrode current collector is copper foil. In some embodiments, the negative electrode current collector is rolled copper foil based on rolling or electrolytic copper foil based on electrolysis.

[0136] In some embodiments, the thickness of the negative electrode current collector is greater than 1 μm or greater than 5 μm. In some embodiments, the thickness of the negative electrode current collector is less than 100 μm or less than 50 μm. In some embodiments, the thickness of the negative electrode current collector is within the range of any two of the above values.

[0137] There are no particular restrictions on the negative electrode active material, as long as it can reversibly absorb and release lithium ions. Examples of negative electrode active materials may include, but are not limited to, carbon materials such as natural graphite and artificial graphite; metals such as silicon (Si) and tin (Sn); or oxides of metal elements such as Si and Sn. Negative electrode active materials can be used alone or in combination.

[0138] The negative electrode active material layer may also include a negative electrode binder. The negative electrode binder improves the bonding between the negative electrode active material particles and the bonding between the negative electrode active material and the current collector. There are no particular limitations on the type of negative electrode binder, as long as it is a material stable to the electrolyte or the solvent used in electrode manufacturing. In some embodiments, the negative electrode binder includes a resin binder. Examples of resin binders include, but are not limited to, fluoropolymers, polyacrylonitrile (PAN), polyimide resins, acrylic resins, polyolefin resins, etc. When a negative electrode slurry is prepared using an aqueous solvent, the negative electrode binder includes, but is not limited to, carboxymethyl cellulose (CMC) or its salts, styrene-butadiene rubber (SBR), polyacrylic acid (PAA) or its salts, polyvinyl alcohol, etc.

[0139] The negative electrode can be prepared by coating a negative electrode slurry containing negative electrode active material, resin binder, etc. onto a negative electrode current collector, drying it, and then calendering it to form a negative electrode active material layer on both sides of the negative electrode current collector, thereby obtaining the negative electrode.

[0140] IV. Separating membrane

[0141] To prevent short circuits, a separator is typically placed between the positive and negative electrodes. In this case, the electrolyte of this application is typically used after penetrating into the separator.

[0142] There are no particular limitations on the material and shape of the separator, as long as it does not significantly impair the effectiveness of this application. The separator may be a resin, glass fiber, inorganic material, or other material formed from a material stable to the electrolyte of this application. In some embodiments, the separator includes a porous sheet or non-woven fabric-like material with excellent liquid retention properties. Examples of materials for resin or glass fiber separators may include, but are not limited to, polyolefins, aromatic polyamides, polytetrafluoroethylene, polyethersulfone, etc. In some embodiments, the polyolefin is polyethylene or polypropylene. In some embodiments, the polyolefin is polypropylene. The above-mentioned separator materials can be used alone or in any combination.

[0143] The separator can also be a material formed by laminating the above-mentioned materials, examples of which include, but are not limited to, a three-layer separator formed by laminating polypropylene, polyethylene, and polypropylene in that order.

[0144] Examples of inorganic materials may include, but are not limited to, oxides such as alumina and silicon dioxide, nitrides such as aluminum nitride and silicon nitride, and sulfates (e.g., barium sulfate, calcium sulfate, etc.). Inorganic materials may be in, but are not limited to, particulate or fibrous forms.

[0145] The separator can be in the form of a thin film, examples of which include, but are not limited to, nonwoven fabrics, woven fabrics, microporous membranes, etc. In the form of a thin film, the pore size of the separator is 0.01 μm to 1 μm, and the thickness is 5 μm to 50 μm. In addition to the above-mentioned independent thin film separator, the following separator can also be used: a separator formed by using a resin-based adhesive to form a composite porous layer containing the above-mentioned inorganic particles on the surface of the positive electrode and / or negative electrode, for example, a separator formed by using fluororesin as an adhesive to form a porous layer of alumina particles with a particle size of less than 1 μm on both sides of the positive electrode.

[0146] The thickness of the separator is arbitrary. In some embodiments, the thickness of the separator is greater than 1 μm, greater than 5 μm, or greater than 8 μm. In some embodiments, the thickness of the separator is less than 50 μm, less than 40 μm, or less than 30 μm. In some embodiments, the thickness of the separator is within the range of any two of the above values. When the thickness of the separator is within the above range, insulation and mechanical strength can be ensured, and the rate capability and energy density of the electrochemical device can be ensured.

[0147] When using porous materials such as porous sheets or nonwoven fabrics as the separator, the porosity of the separator is arbitrary. In some embodiments, the porosity of the separator is greater than 10%, greater than 15%, or greater than 20%. In some embodiments, the porosity of the separator is less than 60%, less than 50%, or less than 45%. In some embodiments, the porosity of the separator is within the range of any two of the above values. When the porosity of the separator is within the above range, insulation and mechanical strength can be ensured, and membrane resistance can be suppressed, giving the electrochemical device good safety characteristics.

[0148] The average pore size of the separator is also arbitrary. In some embodiments, the average pore size of the separator is less than 0.5 μm or less than 0.2 μm. In some embodiments, the average pore size of the separator is greater than 0.05 μm. In some embodiments, the average pore size of the separator is within the range of any two of the above values. If the average pore size of the separator exceeds the above range, a short circuit is likely to occur. When the average pore size of the separator is within the above range, the electrochemical device has good safety characteristics.

[0149] V. Electrochemical Device Components

[0150] Electrochemical device components include electrode arrays, current collectors, housings, and protective elements.

[0151] Electrode group

[0152] The electrode assembly can be either a laminated structure formed by stacking the positive and negative electrodes with the separator membrane in between, or a structure formed by spirally winding the positive and negative electrodes with the separator membrane in between. In some embodiments, the proportion of the electrode assembly's mass in the battery's internal volume (electrode assembly occupancy) is greater than 40% or greater than 50%. In some embodiments, the electrode assembly occupancy is less than 90% or less than 80%. In some embodiments, the electrode assembly occupancy falls within the range of any two of the above values. When the electrode assembly occupancy is within the above range, the capacity of the electrochemical device can be ensured, while suppressing the degradation of characteristics such as repeated charge-discharge performance and high-temperature storage associated with increased internal pressure.

[0153] collector structure

[0154] There are no particular limitations on the current collector structure. In some embodiments, the current collector structure is one that reduces the resistance of the wiring portion and the joint portion. When the electrode group has the above-described laminated structure, it is suitable to use a structure formed by bundling the metal core portions of each electrode layer together and soldering them to the terminals. As the area of ​​an electrode increases, the internal resistance increases; therefore, it is also suitable to provide two or more terminals within the electrode to reduce the resistance. When the electrode group has the above-described wound structure, the internal resistance can be reduced by providing two or more lead structures on the positive and negative electrodes respectively and bundling them together on the terminals.

[0155] outer casing

[0156] There are no particular restrictions on the material of the outer casing, as long as it is a substance stable to the electrolyte used. The outer casing can be, but is not limited to, nickel-plated steel, stainless steel, aluminum or aluminum alloy, magnesium alloy, or a laminated film of resin and aluminum foil. In some embodiments, the outer casing is an aluminum or aluminum alloy metal or a laminated film.

[0157] Metal casings include, but are not limited to, encapsulated and hermetically sealed structures formed by fusing metals together using laser welding, resistance welding, or ultrasonic welding; or riveted structures formed using the aforementioned metals with a resin gasket in between. Casings using the aforementioned laminated films include, but are not limited to, encapsulated and hermetically sealed structures formed by thermally bonding resin layers together. To improve sealing, a resin different from the resin used in the laminated film can be sandwiched between the resin layers. When forming a hermetically sealed structure by thermally bonding resin layers using current collectors, a resin with polar groups or a modified resin with introduced polar groups can be used as the sandwiched resin due to the bonding between the metal and the resin. Furthermore, the shape of the casing is arbitrary, and can be, for example, any of the following: cylindrical, square, laminated, button-shaped, or large.

[0158] Protective components

[0159] Protective components can include positive temperature coefficient (PTC) devices that increase resistance when abnormal heat generation or excessive current flows, temperature fuses, thermistors, and valves (current cut-off valves) that cut off current flowing through the circuit by causing a rapid increase in internal battery pressure or temperature during abnormal heat generation. These protective components can be selected to avoid operation under normal high-current conditions, or they can be designed to prevent abnormal heat generation or thermal runaway even without the protective components.

[0160] VI. Application

[0161] The electrochemical device of this application includes any device in which an electrochemical reaction occurs, and specific examples include all kinds of primary batteries, secondary batteries, fuel cells, solar cells, or capacitors. In particular, the electrochemical device is a lithium secondary battery, including lithium metal secondary batteries or lithium-ion secondary batteries.

[0162] This application also provides an electronic device that includes the electrochemical device described in this application.

[0163] The application of the electrochemical device in this application is not particularly limited, and it can be used in any electronic device known in the prior art. In some embodiments, the electrochemical device of this application can be used in, but is not limited to, laptops, pen input computers, mobile computers, e-book players, portable telephones, portable fax machines, portable copiers, portable printers, stereo headphones, video recorders, LCD TVs, portable cleaners, portable CD players, mini CDs, transceivers, electronic notebooks, calculators, memory cards, portable recorders, radios, backup power supplies, motors, automobiles, motorcycles, electric bicycles, bicycles, lighting fixtures, toys, game consoles, clocks, power tools, flashlights, cameras, household large-capacity batteries, and lithium-ion capacitors, etc.

[0164] The following uses a lithium-ion battery as an example and combines specific embodiments to illustrate the preparation of a lithium-ion battery. Those skilled in the art will understand that the preparation method described in this application is only an example, and any other suitable preparation method is within the scope of this application.

[0165] Example

[0166] I. Preparation of Lithium-ion Batteries

[0167] 1. Preparation of the negative electrode

[0168] Artificial graphite, styrene-butadiene rubber, and sodium carboxymethyl cellulose were mixed with deionized water in a mass ratio of 96%:2%:2% and stirred until homogeneous to obtain a slurry. The slurry was then coated onto a 9μm copper foil. After drying and cold pressing, the foil was cut and tabs were welded to obtain the negative electrode.

[0169] 2. Preparation of the positive electrode

[0170] Lithium cobalt oxide (Hunan Shanshan LC9000E), Super-P, and polyvinylidene fluoride were mixed with N-methylpyrrolidone in a mass ratio of 95%:2%:3% and stirred evenly to obtain the positive electrode active zone slurry. Inorganic filler and polyvinylidene fluoride were mixed with N-methylpyrrolidone in a mass ratio of 90%:10% to obtain the insulating zone slurry. The positive electrode active zone slurry and the insulating zone slurry were simultaneously coated onto a 12μm aluminum foil, dried, cold-pressed, and then cut and welded to obtain the positive electrode. The surface of the positive electrode is as shown in the figure. Figure 3 As shown. The inorganic fillers used and their particle sizes are as follows: boehmite 1.2μm, alumina 1.5μm, silicon dioxide 2μm, titanium dioxide 1.5μm, magnesium oxide 2.5μm, magnesium hydroxide 1.5μm.

[0171] 3. Preparation of electrolyte

[0172] EC, PC, and DEC (weight ratio 1:1:1) were mixed under a dry argon atmosphere, and LiPF6 was added and mixed thoroughly to form a basic electrolyte, wherein the content of LiPF6 was 12%. Electrolytes of different embodiments and comparative proportions were obtained by adding different amounts of additives to the basic electrolyte. The content of each additive in the electrolyte was calculated based on the mass of the electrolyte.

[0173] The abbreviations and names of the components in the electrolyte are shown in the table below:

[0174] 4. Preparation of the separating membrane

[0175] An 8μm polyethylene porous membrane was used as the separator.

[0176] 5. Preparation of lithium-ion batteries

[0177] The obtained positive electrode, separator, and negative electrode are wound in sequence and placed in an outer packaging foil, leaving an injection port. Electrolyte is poured in through the injection port, the battery is sealed, and then processed through formation, capacity testing, and other procedures to produce a lithium-ion battery.

[0178] II. Testing Methods

[0179] 1. Test method for intermittent cycling performance of lithium-ion batteries under high temperature and high pressure

[0180] At 50°C, the lithium-ion battery was charged at a constant current of 0.5C to 4.7V, then charged at a constant voltage with a cutoff current of 0.05C, left to stand for 20 hours, and then discharged at a constant current of 0.5C to 3.0V. The lithium-ion battery was subjected to multiple charge / discharge cycles under these conditions, and the capacity retention rate after 400 cycles was calculated. The capacity retention rate after cycles was calculated using the following formula:

[0181] Capacity retention after cycling = (Discharge capacity after 400 cycles / Discharge capacity after the first cycle) × 100%.

[0182] 2. Test method for overcharge deformation rate of lithium-ion batteries

[0183] At 25°C, the lithium-ion battery was left to stand for 30 minutes, then charged at a constant current rate of 0.5C to 4.7V, and then charged at a constant voltage rate of 4.7V to 0.05C. After standing for 60 minutes, the thickness T1 of the lithium-ion battery was measured. Then, it was charged at a constant current rate of 0.1C for 60 minutes, and then left to stand for 30 minutes. This process was repeated 5 times to bring the lithium-ion battery to 150% state of charge (SOC), and the thickness T2 of the lithium-ion battery was measured.

[0184] Overcharge deformation rate = [(T2-T1) / T1]×100%.

[0185] 3. Test method for high-temperature short-circuit deformation rate of lithium-ion batteries

[0186] At 25°C, the lithium-ion battery was left to stand for 30 minutes, then charged at a constant current rate of 0.5C to 4.7V, and then charged at a constant voltage of 4.7V to 0.05C. After standing for 60 minutes, the thickness T3 of the lithium-ion battery was measured. Then, the battery was short-circuited with 100mΩ for 10 seconds, and the thickness T4 of the lithium-ion battery was measured again.

[0187] Short-circuit deformation rate = [(T4-T3) / T3]×100%.

[0188] III. Test Results

[0189] Table 1 illustrates the effects of the insulating region and electrolyte on the intermittent cycle performance and safety performance of lithium-ion batteries under high temperature and high pressure. The inorganic filler in the insulating region is boehmite. Examples 1-1 to 1-26 in Table 1 show the adjusted content of compounds with cyano groups or compounds with sulfur-oxygen double bonds in the electrolyte. Comparative Example 1-1 has no insulating region at the positive electrode. Comparative Example 1-2 has no insulating region at the positive electrode, and the electrolyte does not contain compounds with cyano groups or compounds with sulfur-oxygen double bonds. The only difference between Examples 1-2 to 1-26 and Example 1-1 is the parameters in Table 1.

[0190] Table 1

[0191] "-" indicates that the substance does not exist.

[0192] As shown in the test results of Examples 1-1 to 1-26, when an insulating region and a positive electrode active material region are provided on the positive electrode, the insulating region contains inorganic fillers, and the electrolyte contains compounds with cyano groups and / or compounds with sulfur-oxygen double bonds, the intermittent cycle performance and safety performance of the lithium-ion battery under high temperature and high pressure are significantly improved. However, as shown in Comparative Examples 1-1 and 1-2, if there is no insulating region in the positive electrode, or if there is neither an insulating region nor compounds with cyano groups and sulfur-oxygen double bonds in the electrolyte, the effect of improving intermittent cycle performance and safety performance under high temperature and high pressure cannot be achieved.

[0193] This may be because the resistance of the interaction region is higher than that of the positive electrode active material region, creating a resistance difference between them. Therefore, during charging and discharging, charge carriers accumulate on the interaction region side instead of utilizing the positive electrode active material contained within it. This results in polarization within the positive electrode, making the interaction region the starting point for overall positive electrode degradation. Compounds with cyano groups or those with sulfur-oxygen double bonds can form a film on the surface of the positive electrode active material, reducing the overall resistance difference between the surface layer of the positive electrode active material region and the interaction region, thus reducing polarization and improving battery performance. Selecting appropriate combinations of cyano-containing compounds, such as two different dinitrile compounds, or a dinitrile compound and a trinitrile compound, can further enhance film formation on the surface of the positive electrode active material and achieve even better results.

[0194] B. Table 2 shows the effects of the insulation zone and electrolyte on the intermittent cycle performance and safety performance of lithium-ion batteries under high temperature and high pressure. In Example 1-1, the inorganic filler was boehmite, and the electrolyte included 4% SN; Examples 2-1 to 2-19 adjusted the composition of the inorganic filler and the electrolyte composition.

[0195] Table 2

[0196] "-" indicates the absence of the substance.

[0197] As shown in Examples 2-1 to 2-19, excellent intermittent cycle performance and safety performance under high temperature and high pressure were also obtained by changing the components of the inorganic filler. Specifically, when the inorganic filler is selected from inorganic substances with weak alkalinity such as boehmite and magnesium hydroxide, the influence on the resistance of the interaction region is smaller, and a further improved effect can be obtained.

[0198] C. Table 3 shows the influence of the relationship between the content (a%) of the compound with a cyano group and the content (b%) of the compound with a sulfur-oxygen double bond on the intermittent cycle performance and safety performance of the lithium-ion battery under high temperature and high pressure. In Example 1-1, the inorganic filler is boehmite, and the electrolyte contains 4% of SN; in Examples 3-1 to 3-15, the inorganic filler is boehmite, and the contents of the compound with a cyano group and the compound with a sulfur-oxygen double bond are adjusted.

[0199] Table 3

[0200] "—" indicates the absence of the substance.

[0201] From the above test results, it can be seen that when the compound with a cyano group and the compound with a sulfur-oxygen double bond are used in combination, the formed film has better stability, and the intermittent cycle performance and safety performance under high temperature and high pressure can also be further improved, especially the improvement of the high-temperature short-circuit safety performance is particularly obvious. More specifically, by controlling the contents of the compound with a cyano group and the compound with a sulfur-oxygen double bond within a suitable range, especially satisfying the relationship: 0.1 ≤ a + b ≤ 15, 0.5 ≤ a / b ≤ 20, the interfacial stability of the positive electrode active material region can be more fully improved, thereby further improving the intermittent cycle performance and safety performance under high temperature and high pressure.

[0202] D. Table 4 shows the influence of the mass per unit area of the positive electrode active material region (A1 mg / 1540.25mm 2 ) and the mass per unit area of the insulating region (A2 mg / 1540.25mm 2 ) on the intermittent cycle performance and safety performance of the lithium-ion battery under high temperature and high pressure. The difference between Examples 4-1 to 4-11 and Example 1-1 is only the parameters listed in Table 4.

[0203] Table 4

[0204] The test results above show that by adjusting the unit area mass of the positive electrode active material region and the unit area mass of the insulating region to satisfy A1 / A2 > 1.2, it is possible to further improve the intermittent cycle performance and safety performance under high temperature and high pressure, especially for high temperature short circuit safety performance. In particular, when A1 / A2 ≥ 2, the performance of the lithium-ion battery is further improved.

[0205] E. Table 5 shows the mass percentage (M1%) of inorganic filler in the insulation zone and the unit area mass (A2 mg / 1540.25 mm²) of the insulation zone. 2 The effects of these methods on the intermittent cycle performance and safety performance of lithium-ion batteries under high temperature and high pressure. Examples 5-1 to 5-9 use the same inorganic fillers and electrolytes as Examples 1-1, differing only in the parameters listed in Table 5.

[0206] Table 5

[0207] The test results above show that by adjusting the unit area mass of the positive electrode active material region and the unit area mass of the insulation region to meet the condition of 0.3≤M1 / A2≤1.5, it is possible to further improve the intermittent cycle performance and safety performance under high temperature and high pressure, especially for the improvement of high temperature short circuit safety performance.

[0208] Table F shows the unit area mass of the positive electrode active material region (A1 mg / 1540.25 mm²). 2 The effects of the content (a%) of compounds with cyano groups on the intermittent cycling and safety performance of lithium-ion batteries under high temperature and high pressure. Examples 6-1 to 6-7 differ from Example 1-1 only in the parameters listed in Table 6.

[0209] Table 6

[0210] The test results above show that by adjusting the unit area mass of the positive electrode active material region and the content of compounds with cyano groups to satisfy A1 / a > 8, it is possible to further improve the intermittent cycling and safety performance under high temperature and high pressure, especially for the improvement of high temperature short circuit safety performance.

[0211] Table 7 shows the effect of positive electrode additive polyols on the intermittent cycle performance and safety performance of lithium-ion batteries under high temperature and high pressure. The only difference between Examples 7-1 to 7-13 and Example 1-1 is the parameters listed in Table 7. The preparation method of the positive electrode in Examples 7-1 to 7-13 is as follows: Lithium cobalt oxide (Hunan Shanshan LC9000E), Super-P, and polyvinylidene fluoride are mixed with N-methylpyrrolidone in a mass ratio of 95%:2%:3%. The additives listed in Table 7 are then added to the slurry, and the mixture is stirred evenly to obtain the positive electrode active area slurry. This positive electrode active area slurry and the insulating area slurry are simultaneously coated onto a 12μm aluminum foil, dried, cold-pressed, and then cut and welded to obtain the positive electrode.

[0212] Table 7

[0213] "-" indicates that the substance does not exist.

[0214] The test results above show that adding 0.1% to 0.5% polyol to the positive electrode slurry also resulted in excellent intermittent cycling performance and safety under high pressure and high temperature. This is likely because the polyol plays a special role in dispersing the coating slurry, greatly reducing polarization and thus suppressing heat-induced side reactions in the battery. Unexpectedly, it also significantly improves the short-circuit deformation rate.

[0215] Throughout this specification, references to "some embodiments," "partial embodiments," "one embodiment," "another example," "example," "specific example," or "partial example" mean that at least one embodiment or example in this application includes a specific feature, structure, material, or characteristic described in that embodiment or example. Therefore, descriptions appearing throughout this specification, such as "in some embodiments," "in an embodiment," "in one embodiment," "in another example," "in an example," "in a specific example," or "example," do not necessarily refer to the same embodiments or examples in this application. Furthermore, specific features, structures, materials, or characteristics described herein can be combined in any suitable manner in one or more embodiments or examples.

[0216] Although illustrative embodiments have been demonstrated and described, those skilled in the art should understand that the above embodiments should not be construed as limiting the present application, and that changes, substitutions and modifications can be made to the embodiments without departing from the spirit, principles and scope of the present application.

Claims

1. An electrochemical device comprising: Positive electrode, negative electrode, and electrolyte. The positive electrode includes a positive electrode current collector and a positive electrode active material region, an insulating region, and an interaction region located on the positive electrode current collector; The interaction region is located between the positive electrode active material region and the insulating region, and is in contact with both the positive electrode active material region and the insulating region; The positive electrode active material region includes a positive electrode active material; The insulating region includes inorganic filler; The interaction region includes the positive electrode active material and the inorganic filler; and The electrolyte satisfies at least one of the following characteristics: (1) The electrolyte includes a compound having a cyano group, wherein the mass percentage of the compound having a cyano group is a% based on the mass of the electrolyte, and the value of a ranges from 0.1 to 15%; (2) The electrolyte includes a compound having a sulfur-oxygen double bond, wherein the mass percentage of the compound having a sulfur-oxygen double bond is b% based on the mass of the electrolyte, and the value of b ranges from 0.001 to 8.

2. The electrochemical device according to claim 1, wherein the electrolyte comprises a compound having a cyano group and a compound having a sulfur-oxygen double bond, wherein a and b satisfy: 0.1 ≤ a + b ≤ 15; and 0.5 ≤ a / b ≤ 20.

3. The electrochemical device according to claim 1, wherein the mass of the positive electrode active material region is A1 mg / 1540.25 mm², and the mass of the insulating region is A2 mg / 1540.25 mm², wherein A1 and A2 satisfy: A1 / A2>1.

2.

4. The electrochemical device according to claim 1, wherein the mass of the positive electrode active material region is Al mg / 1540.25 mm², and the value of Al ranges from 100 to 400.

5. The electrochemical device according to claim 1, wherein the mass percentage of inorganic filler in the insulating region is M1% based on the mass of the insulating region, and the mass of the insulating region is A2g / 1540.25mm², wherein M1 and A2 satisfy: 0.3≤M1 / A2≤1.

5.

6. The electrochemical device according to claim 1, wherein the mass of the positive electrode active material region is A1 mg / 1540.25 mm², wherein A1 and a satisfy: A1 / a>8.

7. The electrochemical device according to claim 1, wherein the inorganic filler comprises at least one of silicon dioxide, alumina, hydrated alumina, titanium dioxide, magnesium oxide, magnesium hydroxide, alumina-doped silicon dioxide, or boehmite.

8. The electrochemical device according to claim 1, wherein the cyano group-containing compound comprises at least one of the following compounds: succinate, glutaronitrile, adiponitrile, 1,5-dicyanopentane, 1,6-dicyanohexane, tetramethylsuccinate, 2-methylglutaronitrile, 2,4-dimethylglutaronitrile, 2,2,4,4-tetramethylglutaronitrile, 1,4-dicyanopentane, 1,2-dicyanobenzene, 1,3-dicyanobenzene, 1,4-dicyanobenzene, Ethylene glycol bis(propionitrile) ether, 3,5-dioxa-heptanenitrile, 1,4-di(cyanoethoxy)butane, diethylene glycol di(2-cyanoethyl) ether, triethylene glycol di(2-cyanoethyl) ether, tetraethylene glycol di(2-cyanoethyl) ether, 1,3-di(2-cyanoethoxy)propane, 1,4-di(2-cyanoethoxy)butane, 1,5-di(2-cyanoethoxy)pentane, ethylene glycol di(4-cyanobutyl) ether, 1,4-dicyano- 2-Butene, 1,4-Dicyano-2-methyl-2-butene, 1,4-Dicyano-2-ethyl-2-butene, 1,4-Dicyano-2,3-dimethyl-2-butene, 1,4-Dicyano-2,3-diethyl-2-butene, 1,6-Dicyano-3-hexene, 1,6-Dicyano-2-methyl-3-hexene, 1,3,5-pentanetricarbonitrile, 1,2,3-propanetricarbonitrile, 1,3,6-hexanetricarbonitrile, 1,2,6-hexanetricarbonitrile Formonitrile, 1,2,3-tris(2-cyanoethoxy)propane, 1,2,4-tris(2-cyanoethoxy)butane, 1,1,1-tris(cyanoethoxymethylene)ethane, 1,1,1-tris(cyanoethoxymethylene)propane, 3-methyl-1,3,5-tris(cyanoethoxy)pentane, 1,2,7-tris(cyanoethoxy)heptane, 1,2,6-tris(cyanoethoxy)hexane, or 1,2,5-tris(cyanoethoxy)pentane; 9. The electrochemical device according to claim 1, wherein the compound having a cyano group comprises at least two dinitrile compounds.

10. The electrochemical device according to claim 1, wherein the compound having a cyano group includes dinitrile compounds and trinitrile compounds.

11. The electrochemical device according to claim 1, wherein the compound having a cyano group comprises a dinitrile compound having an ether bond or a trinitrile compound having an ether bond.

12. The electrochemical device according to claim 1, wherein the compound having a sulfur-oxygen double bond comprises at least one of the following compounds: bicyclic sulfate, bicyclic sulfonyl lactone, vinyl sulfate, propylene sulfate, 1,3-propanesulfonyl lactone, 1,3-propenesulfonyl lactone, methylene disulfonate, or ethylene disulfonate.

13. The electrochemical device according to claim 1, wherein the compound having a sulfur-oxygen double bond comprises a compound of formula 1: ； in, W selected , , or ; Each instance of L is independently selected from a single bond or a methylene group; m can be 1, 2, 3, or 4; n is 0, 1, or 2; and p can be 0, 1, 2, 3, 4, 5, or 6.

14. The electrochemical device according to claim 13, wherein the compound of formula 1 comprises at least one of the following compounds: or .

15. The electrochemical device according to claim 13, wherein the compound of formula 1 comprises at least one of the following compounds: , , , or .

16. The electrochemical device according to claim 12, wherein the bicyclic sulfonyl lactone comprises a compound of formula 2: ； in, A1, A2, A3, and A4 are each independently selected from substituted or unsubstituted alkylene groups. When A1, A2, A3, and A4 are substituted independently, the substituents are selected from halogens, alkyl groups, or halogen-substituted alkyl groups.

17. The electrochemical device according to claim 16, wherein the compound of formula 2 comprises at least one of the following compounds: , , , , , , or .

18. The electrochemical device according to claim 1, wherein the positive electrode active material region comprises a polyol.

19. The electrochemical device according to claim 18, wherein the polyol comprises at least one of the following compounds: methyl glycol, ethylene glycol, propylene glycol, isopentyl glycol, 1,3-butanediol, 1,4-butanediol, diethylene glycol, dipropylene glycol, polyethylene glycol, polypropylene glycol, glycerol, diglycerol, or polyglycerol.

20. An electronic device comprising an electrochemical device according to any one of claims 1-19.

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