Electrochemical apparatus and electronic apparatus including the same

Abstract

An electrochemical device capable of improving high-temperature cycle characteristics and high-temperature interval cycle characteristics, and an electronic device including the same are provided. [Solution] The electrochemical device of the present invention includes a positive electrode and an electrolyte solution, the electrolyte solution including ethylene carbonate (EC), propylene carbonate (PC), and succinonitrile (SN). The positive electrode includes a positive electrode active material, the positive electrode active material including metal element A including at least one of Mg, Zr, and Al. When the mass content of SN is a%, the mass content of EC is b%, and the mass content of PC is c%, relative to the mass of the electrolyte solution, and k is k=b / c, a and k satisfy 1.25≦k≦6 and a / k≧0.2. When the mass content of metal element A is x%, relative to the mass of the positive electrode active material, x satisfies 0.01≦x≦1.

Description

[Technical Field]

[0001] This invention relates to the field of energy storage, and more specifically to electrochemical devices and electronic devices including the same. [Background technology]

[0002] Rechargeable electrochemical devices are considered one of the most attractive energy storage systems due to their advantages such as high energy density, relatively simple reaction mechanisms, high operating voltage, long lifespan, and environmental friendliness. Currently, electrochemical devices such as lithium-ion batteries are widely used in various fields, including wearable devices, smartphones, drones, and laptop computers. [Overview of the project] [Problems that the invention aims to solve]

[0003] With the expansion of applications for electrochemical devices, the market demand for the cycle characteristics of electrochemical devices such as lithium-ion batteries, particularly high-temperature cycle characteristics and high-temperature interval cycle characteristics, is increasing. For example, laptop computers, which are commonly used for work, are always in a charged state while in use, but heat is often generated during both the charging and usage processes. In this process, the laptop computer is first charged to a full charge, maintained at a full charge for several hours, and finally disconnected from the charger and discharged. In this process, the electrochemical device of the laptop computer is required to have not only high-temperature cycle characteristics (i.e., to repeat "charge-discharge" multiple times at high temperatures), but also high-temperature interval cycle characteristics (i.e., to repeat "charge-maintain full charge for several hours-discharge" multiple times at high temperatures). In view of this, the present invention aims to obtain an electrochemical device having excellent high-temperature cycle characteristics and high-temperature interval cycle characteristics in order to meet the above demands.

[0004] In view of the above circumstances, the objective is to provide an electrochemical apparatus and an electronic apparatus including the same that can improve high-temperature cycle characteristics and high-temperature interval cycle characteristics.

[0005] According to one aspect of the present invention, the present invention provides an electrochemical apparatus. The electrochemical apparatus includes a positive electrode and an electrolyte, the electrolyte comprising ethylene carbonate (EC), propylene carbonate (PC), and succinonitrile (SN), the positive electrode comprising a positive electrode active material, the positive electrode active material comprising a metal element A, the metal element A comprising at least one of Mg, Zr, and Al, where a% is the mass content of SN, b% is the mass content of EC, c% is the mass content of PC, and k = b / c, a and k satisfy 1.25 ≤ k ≤ 6 and a / k ≥ 0.2, and where x% is the mass content of metal element A relative to the mass of the positive electrode active material, x satisfies 0.01 ≤ x ≤ 1.

[0006] According to embodiments of the present invention, x and k satisfy x / k ≤ 0.4.

[0007] According to embodiments of the present invention, x and a satisfy 0.001 ≤ x / a ≤ 1.

[0008] According to embodiments of the present invention, the positive electrode active material includes lithium cobalt oxide.

[0009] According to embodiments of the present invention, the positive electrode active material contains lithium nickel cobalt manganese oxide.

[0010] According to an embodiment of the present invention, the positive electrode active material comprises lithium cobalt oxide and lithium nickel cobalt manganese oxide, and when the ratio of the mass of lithium cobalt oxide to the mass of lithium nickel cobalt manganese oxide is g, g satisfies 1 ≤ g ≤ 9.

[0011] According to embodiments of the present invention, the positive electrode active material contains lithium cobalt oxide, and when the median diameter Dv50 of lithium cobalt oxide is given by mμm, m satisfies 8 ≤ m ≤ 20.

[0012] According to an embodiment of the present invention, when the median diameter Dv50 of the positive electrode active material is y μm, y satisfies 2 ≤ y ≤ 25.

[0013] According to an embodiment of the present invention, x and y satisfy 10 ≤ y / x ≤ 900.

[0014] According to the embodiment of the present invention, y and a satisfy 1 ≤ y / a ≤ 36.

[0015] According to embodiments of the present invention, the electrolyte further contains lithium difluorophosphate (LiPO2F2), and when the mass content of LiPO2F2 is d% relative to the mass of the electrolyte, d satisfies the condition 0.01 ≤ d ≤ 0.5.

[0016] According to embodiments of the present invention, x and d satisfy 0.05 ≤ d / x ≤ 25.

[0017] According to embodiments of the present invention, k and d satisfy 0.001 ≤ d / k ≤ 0.4.

[0018] According to another aspect of the present invention, the present invention further provides an electronic apparatus, including an electrochemical apparatus described in the embodiments of the present invention. [Modes for carrying out the invention]

[0019] The embodiments of the present invention will be described in detail below. The embodiments of the present invention should not be construed as limiting the present invention.

[0020] As used in this invention, the terms “include,” “encompass,” and “contain” are used in their open and non-restrictive sense.

[0021] In addition, in this specification, amounts, ratios, and other numerical values may be presented in a range format. It should be understood that such a range format is used for convenience and brevity. This range format should be flexibly understood to include not only the numerical values explicitly specified as range limitations, but also each and every numerical value or sub-range included in the above range as if each numerical value and sub-range were explicitly specified.

[0022] In the embodiments for carrying out the invention and the claims, a list of items connected by terms such as "one or more of", "one or more of", "at least one kind of", or other similar terms means any combination of the listed items. For example, when items A and item B are listed, the short phrase "at least one kind of A and B" means only A, only B, or A and B. In other examples, when items A, item B, and item C are listed, the short phrase "at least one kind of A, B, and C" means only A, 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 include a single element or a plurality of elements. Item B may include a single element or a plurality of elements. Item C may include a single element or a plurality of elements.

[0023] As an important component of an electrochemical device, an electrolyte is used to transport lithium ions between the positive electrode and the negative electrode and to achieve continuous insertion and extraction of lithium ions in the materials of the positive electrode and the negative electrode to perform the charge-discharge function. Therefore, the electrolyte is important for the electrochemical device to obtain excellent high-temperature characteristics.

[0024] As one of the main features of the electrolytic solution described in the present invention, the electrolytic solution simultaneously contains ethylene carbonate (EC), propylene carbonate (PC), and succinonitrile (SN). With respect to the mass of the electrolytic solution, the mass content of succinonitrile is set as a%, the mass content of ethylene carbonate is set as b%, the mass content of propylene carbonate is set as c%, and when k = b / c, a and k satisfy 1.25 ≤ k ≤ 6 and a / k ≥ 0.2.

[0025] The reason why the present invention proposes the above electrolytic solution is based on the finding that by adding a certain content of ethylene carbonate to the electrolytic solution, the high-voltage withstand characteristics and high-temperature stability of the electrolytic solution itself can be improved. However, if the content of ethylene carbonate in the electrolytic solution is too high, gas generation becomes serious, which is disadvantageous to the high-temperature interval cycle characteristics. In contrast, propylene carbonate has excellent high-temperature stability, and its addition can compensate for the defects of ethylene carbonate. Therefore, by adding both ethylene carbonate and propylene carbonate to the electrolytic solution, the high-temperature stability of the electrolytic solution itself can be improved, thereby improving the high-temperature interval cycle characteristics and high-temperature cycle characteristics of the electrochemical device. In addition, by adding a nitrile compound to the electrolytic solution, the transition metal in the positive electrode active material (for example, metal cobalt in lithium cobaltate) can be effectively stabilized, the elution of the transition metal can be reduced, and the structure of the positive electrode active material can be stabilized, thereby further improving the cycle stability and high-temperature characteristics of the electrochemical device. Here, compared with other nitrile compounds, the effect of adding succinonitrile (SN) to the electrolytic solution is particularly prominent. This is because the cyano group in the structure of succinonitrile coordinates with the metal ions in the positive electrode active material to form a complex, which can reduce the side reaction between the positive electrode active material and the electrolytic solution and reduce the generation of gas inside the electrochemical device, and the cyano group reacts with water or hydrogen fluoride in the electrolytic solution, which can enhance the cycle stability of the electrolytic solution and further improve the high-temperature cycle characteristics of the electrochemical device.

[0026] However, the present invention has found that although propylene carbonate has excellent high-temperature stability, it is prone to reductive decomposition on the surface of the negative electrode graphite at lithium storage potential, destroying the graphite structure, affecting the release of active ions, and further affecting the cycle stability of the electrochemical apparatus. Furthermore, while succinonitrile can effectively stabilize the transition metal in the positive electrode active material, if added in large amounts, it causes an increase in the impedance of the electrochemical apparatus and leads to large polarization. Therefore, the present invention adjusts the mass content of ethylene carbonate, propylene carbonate, and succinonitrile in the electrolyte and their blending ratios so that a and k satisfy 1.25 ≤ k ≤ 6 and a / k ≥ 0.2, thereby promoting the synergistic effect of the three and further improving the high-temperature cycle characteristics and high-temperature interval cycle characteristics of the electrochemical apparatus. In some examples, k is 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, or 6, or may be in the range of any two of the above values, but is not limited to these. In some embodiments, a / k may be 0.2, 0.5, 1, 1.5, or 2, or within the range of any two of the above values, but is not limited to these.

[0027] The positive electrode, as a crucial component of an electrochemical apparatus, significantly influences the performance of its electrochemical properties. The positive electrode comprises a positive electrode current collector and a positive electrode active material layer located on at least one surface of the positive electrode current collector. The positive electrode active material layer contains a positive electrode active material, such as lithium ions, which can reversibly intercept and release active ions. The positive electrode active material layer may be a single layer or multiple layers, and each layer of the multiple positive electrode active material may contain the same or different positive electrode active materials. The positive electrode active material layer further comprises a binder and / or a conductive agent.

[0028] One of the main features of the positive electrode described in the present invention is that the positive electrode active material is doped with metal element A, and metal element A includes at least one of Mg, Zr, and Al, and when the mass content of metal element A is x% of the mass of the positive electrode active material, x satisfies 0.01 ≤ x ≤ 1.

[0029] The present invention proposes the above-mentioned positive electrode because it has been found that doping the positive electrode active material with at least one of Mg, Zr, and Al, compared to other metal elements, can further stabilize the structure of the positive electrode active material. For example, when the positive electrode active material contains the active metal cobalt element (Co), element A occupies the lattice gaps, and the AO bond formed after the positive electrode releases lithium is stronger than the Co-O bond. This delays the release of oxygen, prevents the dissolution of Co, and achieves the objective of stabilizing the structure of the positive electrode active material. Furthermore, by controlling the mass content of metal element A in the positive electrode active material to within the range of 0.01% to 1%, the release of active ions such as lithium ions in the positive electrode active material can be promoted, polarization can be reduced, and the high-temperature cycle characteristics and high-temperature interval cycle characteristics can be further improved. In some embodiments, x may be 0.02, 0.05, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, or 1, or within the range of any two of the above values, but is not limited to these.

[0030] Furthermore, it is believed that the high-temperature cycle characteristics and high-temperature interval cycle characteristics of the electrochemical apparatus can be further improved by using an electrolyte and positive electrode having the above-mentioned characteristics in combination because the electrolyte and positive electrode have a good matching relationship and can mutually promote the volatilization of each other's effects.

[0031] Furthermore, by adjusting the matching of several components in the electrolyte with the positive electrode active material, the high-temperature cycle characteristics and high-temperature interval cycle characteristics of the electrochemical apparatus can be further improved.

[0032] In some embodiments, further improvements in the high-temperature characteristics can be achieved by adjusting the relationship between the x% content of doped element A in the positive electrode active material and the mixing ratio k of ethylene carbonate and propylene carbonate in the electrolyte. The reason is as follows: Propylene carbonate has excellent high-temperature stability, but it easily decomposes at the negative electrode and destroys the negative electrode structure. In contrast, ethylene carbonate can decompose at the surface of the negative electrode to form a stable SEI film, and can weaken the effect of propylene carbonate on decomposing the negative electrode interface and destroying the negative electrode. By using both together, the high-voltage withstand voltage characteristics and high-temperature stability of the electrolyte itself can be improved. On the other hand, doped element A can stabilize the structure of the positive electrode active material, and by adjusting the relationship between the content of doped element A and the mixing ratio k of ethylene carbonate and propylene carbonate, the high-voltage withstand voltage characteristics and high-temperature stability of the electrolyte can be improved, as well as the structural stability of the positive electrode, further improving the high-temperature cycle characteristics and high-temperature interval cycle characteristics of the electrochemical apparatus. In some embodiments, x and k satisfy x / k ≤ 0.4. In some embodiments, x and k satisfy x / k ≤ 0.3, x / k ≤ 0.2, or x / k ≤ 0.1.

[0033] In some embodiments, further improvements in high-temperature characteristics can be achieved by adjusting the relationship between the content of doped element A (x%) in the positive electrode active material and the content of succinonitrile (a%) in the electrolyte. This is because the cyano groups in the structure of succinonitrile coordinate with metal ions in the positive electrode active material to form complexes, thereby stabilizing the structure of the positive electrode active material. By adjusting the relationship between the content of the two, the structure of the positive electrode active material can be stabilized well, and the electrolyte has a relatively low impedance. In some embodiments, x and a satisfy 0.001 ≤ x / a ≤ 1. In some embodiments, x / a is 0.01, 0.05, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, or 1, or may be within the range of any two of the above values, but is not limited to these.

[0034] If the positive electrode active material particles are primary particles, the median diameter Dv50 of the positive electrode active material refers to the primary particle diameter of the positive electrode active material particles. If the primary particles of the positive electrode active material aggregate to form secondary particles, the median diameter Dv50 of the positive electrode active material refers to the secondary particle diameter of the positive electrode active material particles.

[0035] In some embodiments, when the median diameter Dv50 of the positive electrode active material is y μm, y satisfies 2 ≤ y ≤ 25. In some embodiments, the median diameter Dv50 of the positive electrode active material is 2 μm, 3 μm, 5 μm, 8 μm, 10 μm, 13 μm, 15 μm, 18 μm, 20 μm, 23 μm, or 25 μm, or may be within the range of any two of the above values, but is not limited to these. When the median diameter Dv50 of the positive electrode active material is within the above range, it is possible to ensure good contact between the positive electrode active material particles, as well as to ensure that the contact area between the positive electrode active material and the electrolyte is within an appropriate range. This reduces the occurrence of side reactions, avoids excessive consumption of the electrolyte during the electrochemical cycle, and also reduces the risk of the positive electrode active material particles cracking due to cold pressing during the electrode preparation process.

[0036] In some examples, the positive electrode active material includes one or more of the following: lithium cobalt oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminate, lithium manganese oxide, lithium iron manganese phosphate, lithium vanadium phosphate, lithium vanadyl phosphate, lithium iron phosphate, lithium titanate, and lithium-containing manganese-based materials.

[0037] In some examples, the chemical formula of lithium cobalt oxide may be LiCoO2, but is not limited thereto.

[0038] In some examples, the chemical formula for lithium nickel-cobalt manganese oxide is LiNi 0.6 Co 0.2 Mn 0.2O2 may also be used, but is not limited to it.

[0039] In some embodiments, the positive electrode active material comprises at least one of lithium cobalt oxide and lithium nickel cobalt manganese oxide. When the positive electrode active material comprises both lithium cobalt oxide and lithium nickel cobalt manganese oxide, g is the ratio of the mass of lithium cobalt oxide to the mass of lithium nickel cobalt manganese oxide relative to the mass of the positive electrode active material, where g satisfies 1 ≤ g ≤ 9. In some embodiments, g may be 1, 2, 3, 4, 5, 6, 7, 8, or 9, or within the range of any two of the above values, but is not limited to these.

[0040] In some embodiments, the positive electrode active material contains lithium cobalt oxide, and when the median diameter Dv50 of lithium cobalt oxide is given by mμm, m satisfies 8 ≤ m ≤ 20. By controlling the median diameter of lithium cobalt oxide within the above range, it is possible not only to enhance the electrolyte penetration effect on the positive electrode active material but also to improve the rate of intercalation and release of metal ions such as lithium ions in the positive electrode active material, thereby further improving the electrochemical properties of the electrochemical apparatus.

[0041] In some embodiments, the median diameter Dv50 (y μm) of the positive electrode active material and the content of metal element A in the positive electrode active material (x%) satisfy 10 ≤ y / x ≤ 900. When y / x is within the above range, the structural stability and thermal stability at high temperatures of the positive electrode active material can be simultaneously improved, thereby further enhancing the high-temperature cycle characteristics and high-temperature interval cycle characteristics of the electrochemical apparatus. In some embodiments, y and x satisfy 20 ≤ y / x ≤ 800, 20 ≤ y / x ≤ 600, or 50 ≤ y / x ≤ 500.

[0042] In some examples, the median diameter Dv50 (y μm) of the positive electrode active material and the mass content a% of succinonitrile in the electrolyte satisfy 1 ≤ y / a ≤ 36. When y / a is within the above range, the complex formation between succinonitrile and the transition metal in the positive electrode active material is further promoted, and the elution of the transition metal is reduced, thereby improving the structural stability and thermal stability at high temperatures of the positive electrode active material. This further improves the high-temperature cycle characteristics and high-temperature interval cycle characteristics of the electrochemical apparatus. In some examples, y and a satisfy 2 ≤ y / a ≤ 30, 5 ≤ y / a ≤ 20, or 5 ≤ y / a ≤ 15.

[0043] In some embodiments, the electrolyte further contains lithium difluorophosphate (LiPO2F2). The addition of lithium difluorophosphate allows for the formation of a structurally stable SEI film on the surface of the negative electrode through decomposition and reduction, thereby further improving the high-temperature cycle characteristics and high-temperature interval cycle characteristics of the electrochemical apparatus. Specifically, this is reflected in the fact that the addition of lithium difluorophosphate increases the LiF component in the SEI film, thereby enhancing the stability of the SEI film and further reducing the occurrence of side reactions.

[0044] In some embodiments, when the mass content of LiPO2F2 is d% relative to the mass of the electrolyte, d satisfies the condition 0.01 ≤ d ≤ 0.5. When the mass content of LiPO2F2 is within the above range, LiPO2F2 can dissolve sufficiently in the electrolyte, thereby significantly improving the high-temperature characteristics of the electrochemical apparatus, ensuring the formation of an SEI film with appropriate impedance, and reducing polarization. In some embodiments, d may be 0.01, 0.1, 0.2, 0.3, 0.4, or 0.5, or in the range between any two of the above values, but is not limited to these.

[0045] In some embodiments, the mass content d% of LiPO2F2 and the content x% of metal element A in the positive electrode active material satisfy 0.05 ≤ d / x ≤ 25. When d / x is within the above range, LiPO2F2 has better solubility in the electrolyte, forms a SEI film with low impedance at the negative electrode, and the metal element in the positive electrode active material further stabilizes the structure of the positive electrode active material, promotes the release of active ions such as lithium ions in the positive electrode active material, and achieves simultaneous improvement of the cycle stability of the positive and negative electrodes, thereby further improving the high-temperature cycle characteristics and high-temperature interval cycle characteristics of the electrochemical apparatus. In some embodiments, d / x is 0.05, 0.1, 0.5, 1, 3, 5, 7, 9, 12, 15, 20, or 25, or may be in the range between any two of the above values, but is not limited to these.

[0046] In some embodiments, the mass content d% of LiPO2F2 and the mixing ratio k of ethylene carbonate and propylene carbonate in the electrolyte satisfy the condition 0.001 ≤ d / k ≤ 0.4. When d / k is within the above range, the electrolyte has lower impedance and better high-temperature resistance, and an SEI film with lower impedance can be formed at the negative electrode interface, thereby further improving the high-temperature cycle characteristics and high-temperature interval cycle characteristics of the electrochemical apparatus. In some embodiments, d / k may be 0.001, 0.05, 0.1, 0.2, 0.3, or 0.4, or in the range between any two of the above values, but is not limited to these.

[0047] The surface of the positive electrode active material may have substances with a different composition attached to it. Examples of surface-attached substances include, but are not limited to, at least one of alumina, silica, titanium dioxide, zirconia, 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; at least one of lithium carbonate, calcium carbonate, and magnesium carbonate; and carbon. By attaching substances 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 increasing the service life of the electrochemical apparatus.

[0048] In this invention, a positive electrode active material having a substance with a different composition attached to its surface is also referred to as a "positive electrode active material."

[0049] In some embodiments, the shape of the positive electrode active material particles includes, but is not limited to, block-shaped, polyhedral, spherical, ellipsoidal, plate-shaped, needle-shaped, and columnar. In some embodiments, the positive electrode active material particles include primary particles, secondary particles, or a combination thereof. In some embodiments, primary particles may aggregate to form secondary particles.

[0050] In some examples, the binder in the positive electrode active material layer includes, but is not limited to, polyvinyl alcohol, hydroxypropyl cellulose, polyvinylidene fluoride, diacetylcellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene oxy-containing polymer, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, acrylated (esterified) styrene-butadiene rubber, epoxy resin, or nylon.

[0051] In some examples, the conductive agent in the positive electrode active material layer includes, but is not limited to, carbon-based materials, metallic materials, conductive polymers, and mixtures thereof. In some examples, the carbon-based material is selected from natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fibers, and any combination thereof. In some examples, the metallic material is selected from metal powders, metal fibers, copper, nickel, aluminum, and silver. In some examples, the conductive polymer includes polyphenylene derivatives.

[0052] In the present invention, the type of positive electrode current collector is not particularly limited and may be any known material suitable for use as a positive electrode current collector. Examples of positive electrode current collectors include, but are not limited to, metallic materials such as aluminum, stainless steel, nickel plating, titanium, and tantalum; and carbon materials such as carbon cloth and carbon paper. In some embodiments, the positive electrode current collector is a metallic material. In some embodiments, the positive electrode current collector is aluminum. To reduce the electronic contact resistance between the positive electrode current collector and the positive electrode active material layer, the surface of the positive electrode current collector may contain a conductive additive. Examples of conductive additives include, but are not limited to, carbon and precious metals such as gold, platinum, and silver.

[0053] A positive electrode can be manufactured by forming a positive electrode active material layer containing a positive electrode active material, a binder, or a conductive agent on a current collector. The manufacture of a positive electrode using a positive electrode active material can be carried out by conventional methods. Specifically, the positive electrode active material, binder, and optionally a conductive agent and a thickener are dry-mixed to form a sheet, and the resulting sheet is pressed onto the positive electrode current collector; or, these materials are dissolved or dispersed in a liquid medium to form a slurry, and this slurry is applied to the positive electrode current collector and dried to form a positive electrode active material layer on the current collector. This allows a positive electrode to be obtained. In some embodiments, the liquid medium may contain, but is not limited to, N-methylpyrrolidone.

[0054] In some embodiments, the electrolyte further comprises any non-aqueous solvent that can be used as a solvent for electrolytes known in the prior art.

[0055] In some examples, the non-aqueous solvent includes, but is not limited to, one or more of the following: cyclic carbonate esters, linear carbonate esters, cyclic carboxylic acid esters, linear carboxylic acid esters, cyclic ethers, linear ethers, and aromatic fluorine-containing solvents.

[0056] In some examples, the cyclic carbonate ester may include, but is not limited to, but but also includes butylene carbonate.

[0057] In some examples, the chain-like carbonate ester may include, but is not limited to, one or more of dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate (DEC), methyl-n-propyl carbonate, ethyl-n-propyl carbonate, and di-n-propyl carbonate.

[0058] In some examples, the cyclic carboxylic acid ester may include, but is not limited to, one or more of γ-butyrolactone and γ-valerolactone. In some examples, some of the hydrogen atoms of the cyclic carboxylic acid ester may be substituted with fluorine.

[0059] In some examples, the linear carboxylic acid ester may include, but is 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 examples, some of the hydrogen atoms of the linear carboxylic acid ester may be substituted with fluorine. In some examples, the fluorine-substituted linear carboxylic acid ester may include, but is not limited to, methyl trifluoroacetate, ethyl trifluoroacetate, propyl trifluoroacetate, butyl trifluoroacetate, and 2,2,2-trifluoroethyl trifluoroacetate.

[0060] In some examples, the cyclic ether may include, but is not limited to, one or more of tetrahydrofuran, 2-methyltetrahydrofuran, 1,3-dioxolane, 2-methyl-1,3-dioxolane, 4-methyl-1,3-dioxolane, 1,3-dioxane, 1,4-dioxane, and dimethoxypropane.

[0061] In some examples, the examples of the linear 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.

[0062] In some examples, the aromatic fluorine-containing solvent includes, but is not limited to, one or more of the following: fluorobenzene, difluorobenzene, trifluorobenzene, tetrafluorobenzene, pentafluorobenzene, hexafluorobenzene, and trifluoromethylbenzene.

[0063] In some embodiments, the electrolyte is not particularly limited, and any known electrolyte can be used as is.Examples of electrolytes include 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 FSO3Li, CH3SO3Li, CH2FSO3Li, CHF2SO3Li, CF3SO3Li, and CF3CF2SO3 Li, lithium sulfonate salts such as CF3CF2CF2SO3Li, CF3CF2CF2CF2SO3Li; LiN(FCO)2, LiN(FCO)(FSO2), LiN(FSO2)2, LiN(FSO2)(CF3SO2), LiN(CF3SO2)2, LiN(C2F5SO2)2, lithium imide lithium salts such as lithium cyclic 1,2-perfluoroethanedisulfonylimide, lithium cyclic 1,3-perfluoropropanedisulfonylimide, LiN(CF3SO2)(C4F9SO2); LiC(FSO2)3, LiC(CF3SO2)3, Li Methylated lithium salts such as C(C2F5SO2)3; lithium (malonato) borate salts such as lithium bis(malonato)borate and lithium difluoro(malonato)borate; lithium (malonato) phosphate salts such as lithium tris(malonato)phosphate, lithium difluorobis(malonato)phosphate, and lithium tetrafluoro(malonato)phosphate; and LiPF4(CF3)2, LiPF4(C2F5)2, LiPF4(CF3SO2)2, LiPF4(C2F5SO2)2, LiBF3CF3, LiBF3C2F5, L This may include, but is not limited to, fluorine-containing organolithium salts such as iBF3C3F7, LiBF2(CF3)2, LiBF2(C2F5)2, LiBF2(CF3SO2)2, and LiBF2(C2F5SO2)2; lithium oxalatoborate salts such as lithium difluoro(oxalato)borate and lithium bis(oxalate)borate; and lithium oxalatophosphate salts such as lithium tetrafluoro(oxalato)phosphate, lithium difluorobis(oxalato)phosphate, and lithium tris(oxalato)phosphate.

[0064] In some embodiments, the electrolyte comprises at least one of LiPF6, LiBF4, LiSbF6, F3SO3Li, CF3SO3Li, LiN(FSO2)2, LiN(FSO2)(CF3SO2), and LiN(CF3SO2)2. In the present invention, the electrolyte content is not particularly limited as long as it does not impair the effects of the present invention. In some embodiments, the mass content of the electrolyte is 10% to 15% of the mass of the electrolyte. When the mass content of the electrolyte is within the above range, the viscosity of the electrolyte can be set to an appropriate range, making it easier to ensure good electrical conductivity.

[0065] In the present invention, 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, and the negative electrode active material layer includes a negative electrode active material. The negative electrode active material layer may be a single layer or multiple layers, and each layer of the multiple negative electrode active material may contain the same or different negative electrode active material. The negative electrode active material is any material that can reversibly intercept and release active ions such as lithium ions. Examples of negative electrode active materials include lithium metal, structured lithium metal, natural graphite, artificial graphite, mesocarbon microbeads (MCMB), hard carbon, soft carbon, silicon, silicon-carbon composite, Li-Sn alloy, Li-Sn-O alloy, Sn, SnO, SnO2, and spinel-structured lithium TiO2-Li4Ti5O 12 , or may contain Li-Al, but is not limited to these.

[0066] In the present invention, there are no particular limitations on the type of negative electrode current collector, and any known current collector can be used. Examples of negative electrode current collectors include, but are not limited to, aluminum foil, copper foil, nickel foil, stainless steel foil, or nickel-plated steel foil. In some embodiments, the negative electrode current collector is copper foil.

[0067] The negative electrode active material layer may further contain a negative electrode binder, a conductive agent, or a thickener. The negative electrode binder can improve the bonding between negative electrode active material particles and the bonding between the negative electrode active material and the current collector. The type of negative electrode binder is not particularly limited and can be any material that is stable to the electrolyte or solvent used in the manufacture of the electrode. In some examples, the negative electrode binder includes, but is not limited to, polyvinyl alcohol, carboxymethylcellulose, hydroxypropylcellulose, diacetylcellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene oxy-containing polymer, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, acrylated (esterified) styrene-butadiene rubber, epoxy resin, or nylon.

[0068] In some examples, the conductive agent includes, but is not limited to, at least one of carbon-based materials, metallic materials, and conductive polymers. In some examples, the carbon-based material includes at least one of natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, and carbon fibers. In some examples, the metallic material includes at least one of metal powder, metal fibers, copper, nickel, aluminum, and silver. In some examples, the conductive polymer includes a polyphenylene derivative. In some examples, the thickener includes sodium carboxymethylcellulose.

[0069] The negative electrode can be prepared by known preparation methods in the art. For example, a negative electrode can be obtained by applying a negative electrode active material layer slurry containing a negative electrode active material, a binder, or a conductive agent to a negative electrode current collector, and then applying the slurry to both sides of the negative electrode current collector to form a negative electrode active material layer. In some examples, the solvent may include water or the like, but is not limited thereto.

[0070] In some embodiments, the electrochemical apparatus of the present invention is provided with a separator between the positive and negative electrodes to prevent short circuits. In the present invention, the material and shape of the separator are not particularly limited and may be any technology disclosed in the prior art, as long as they do not impair the effects of the present invention.

[0071] For example, the separator may include a base layer and a surface treatment layer. The base layer may include a porous sheet or a nonwoven fabric-like material with excellent liquid retention properties. Examples of materials for the resin or glass fiber separator may include, but are not limited to, polyolefins, aromatic polyamides, polytetrafluoroethylenes, and polyethersulfones. In some examples, the polyolefin is polyethylene or polypropylene. In some examples, the polyolefin is polypropylene. The above separator materials may be used individually or in any combination. The base layer may be a material formed by laminating the above materials, and examples include, but are not limited to, a three-layer separator formed by laminating polypropylene, polyethylene, and polypropylene in that order.

[0072] A surface treatment layer is provided on at least one surface of the base layer, and the surface treatment layer may be a polymer layer or an inorganic layer, or a layer formed by mixing a polymer and an inorganic material. Examples of inorganic materials may include, but are not limited to, oxides such as alumina and silica, nitrides such as aluminum nitride and silicon nitride, and sulfates (e.g., barium sulfate, calcium sulfate, etc.). The form of the inorganic material may include, but is not limited to, particulate or fibrous forms. The polymer layer contains a polymer, and the polymer material includes at least one of polyamide, polyacrylonitrile, acrylic acid ester polymer, polyacrylic acid, polyacrylate, polyvinylidene fluoride, and poly(vinylidene fluoride-hexafluoropropylene).

[0073] The electrochemical apparatus assembly includes an electrode group, a current collection structure, a case, and protective elements.

[0074] The electrode group may be either a stacked structure in which a positive electrode and a negative electrode are stacked with a separator in between, or a structure in which a positive electrode and a negative electrode are wound together with a separator in between.

[0075] The current collection structure is designed to reduce the resistance of the wiring and connection parts. When the electrode group has the above-described laminated structure, a structure formed by bundling the metal core portions of each electrode layer and welding them to the terminal is preferably used. When the electrode group has the above-described wound structure, the internal resistance can be reduced by providing two or more lead structures for both the positive and negative electrodes and bundling them to the terminal.

[0076] The material of the case is not particularly limited and can be any substance that is stable with respect to the electrolyte used. The case may be made of metals such as nickel-plated steel, stainless steel, aluminum or aluminum alloy, magnesium alloy, or laminated film of resin and aluminum foil, but is not limited to these. In some embodiments, the outer case is made of aluminum or aluminum alloy metal or laminated film. The shape of the case is also arbitrary and may be any one of the following, for example, cylindrical, rectangular, laminated, or button-shaped.

[0077] As protective elements, a positive temperature coefficient that increases resistance when abnormal heat generation or excessive current flows, thermal fuses, thermistors, and current interruption valves are used. The above protective elements can be selected to be non-functional during normal use at high currents, but it is also possible to design the system in such a way that abnormal heat generation or thermal runaway does not occur even without protective elements.

[0078] The electrochemical apparatus of the present invention includes, but is not limited to, any apparatus in which an electrochemical reaction occurs, and may include a lithium-ion battery. In some embodiments, the electrochemical apparatus of the present invention comprises a positive electrode containing a positive electrode active material capable of intercepting and releasing active ions, a negative electrode containing a negative electrode active material capable of intercepting and releasing active ions, and an electrolyte as described in the above embodiments.

[0079] The present invention further provides an electronic apparatus including the electrochemical apparatus described in the present invention.

[0080] The applications of the electrochemical apparatus of the present invention are not particularly limited and can be used in any electronic device known in the prior art. In some embodiments, the electrochemical apparatus of the present invention can be used in, but is not limited to, laptop computers, pen-input computers, mobile computers, e-book players, mobile phones, portable facsimile machines, portable copiers, portable printers, stereo headsets, video recorders, LCD televisions, portable cleaners, portable CD players, mini CDs, transceivers, electronic notebooks, calculators, memory cards, portable tape recorders, radios, backup power supplies, motors, automobiles, motorcycles, electric assist bicycles, bicycles, lighting fixtures, toys, game consoles, clocks, power tools, strobes, cameras, large household storage batteries, and lithium-ion capacitors.

[0081] The present invention will be further explained below with reference to specific examples, using lithium-ion batteries as an example. Those skilled in the art should understand that the preparation methods described in the present invention are merely illustrative, and that any other suitable preparation methods are within the scope of the present invention.

[0082] 1. Preparation of lithium-ion batteries 1. Preparation of the negative electrode Artificial graphite as the negative electrode active material, styrene-butadiene rubber (SBR) as a binder, and sodium carboxymethylcellulose (CMC) as a thickener were thoroughly mixed with an appropriate amount of deionized water in a weight ratio of 97.4:1.2:1.4 to form a uniform negative electrode slurry. This slurry was applied to copper foil, which was the negative electrode current collector, dried, and cold-pressed to obtain the negative electrode.

[0083] 2. Preparation of the positive electrode A homogeneous positive electrode slurry was formed by thoroughly stirring and mixing lithium cobaltate or lithium nickel-cobalt-manganate doped with Mg, Zr, or Al, acetylene black as a conductive agent, and polyvinylidene fluoride (PVDF) as a binder in a weight ratio of 96:2:2 with an appropriate amount of N-methylpyrrolidone (NMP) solvent. This slurry was applied to aluminum foil, which served as the positive electrode current collector, dried, and cold-pressed to obtain the positive electrode.

[0084] 3. Preparation of the electrolyte In a glove box under an argon gas atmosphere with a water content of <10 ppm, a fixed mass of ethylene carbonate (EC), propylene carbonate (PC), and diethyl carbonate (DEC) were uniformly mixed. Furthermore, a thoroughly dried lithium salt, LiPF6, was dissolved in the above non-aqueous solvent to form a base electrolyte. A fixed mass of additives (for example, nitrile compound additives SN and LiPO2F2) were added to the obtained base electrolyte and uniformly mixed to obtain the electrolyte. Here, the mass content of LiPF6 relative to the mass of the electrolyte was 12.5%, the mass content of EC, PC, SN, and LiPO2F2 are shown in the table of examples, and the remainder was the mass content of DEC in the electrolyte.

[0085] 4. Preparation of the separator A porous polyethylene (PE) polymer film was used as the separator.

[0086] 5. Preparation of lithium-ion batteries The positive electrode, separator, and negative electrode were stacked in order, with the separator interposed between them to act as an isolation element. The stack was then wound up to obtain a cell. The cell was placed in an outer foil, the prepared electrolyte was injected into the dried cell, and the lithium-ion battery was completed through processes such as vacuum sealing, standing, formation, and shaping. Lithium-ion batteries of the examples and comparative examples were prepared using the above preparation method, and the following measurements were performed on the lithium-ion batteries, positive electrode active material, and electrolyte.

[0087] 2.Measurement method 1. Measurement of high-temperature cycles The battery was placed in a 45°C incubator and charged to 4.4V with a constant current of 1.5C, then charged at a constant voltage of 0.05C at 4.4V, and finally discharged to 3.0V with a constant current of 1.0C. This constituted one charge-discharge cycle, and the initial discharge capacity was denoted as C1. After performing 500 charge-discharge cycles as described above, the discharge capacity after the 500th cycle was defined as C1. 500 The following formula was used to calculate the cycle capacity retention rate of the lithium-ion battery at 45°C.

[0088]

number

[0089] 2. Measurement of high-temperature interval cycles The battery was placed in a 45°C incubator and charged to 4.4V with a constant current of 0.5C, then charged at 4.4V to 0.05C at a constant voltage, maintained for 19.5 hours, and then discharged to 3.0V with a constant current of 0.5C. This constituted one charge-discharge cycle, and the initial discharge capacity was recorded as A1, and the thickness of the battery in a fully charged state during the first cycle was recorded as T1. This charge-discharge cycle was performed 23 times. Subsequently, the battery was charged to 4.35V with a constant current of 0.5C, then charged at 4.35V to 0.05C at a constant voltage, maintained for 19.5 hours, and then discharged to 3.0V with a constant current of 0.5C. This charge-discharge cycle was performed 113 more times, and the discharge capacity after the end of the final cycle was recorded as A 136And the thickness of the battery in its fully charged state during the last cycle is T 136 The following formula was used to calculate the interval cycle capacity retention rate and thickness increase rate of the lithium-ion battery at 45°C.

[0090]

number

[0091]

number

[0092] 3. Measurement of median diameter Dv50 of positive electrode active material particles The particle size of the positive electrode active material particles was measured using a Malvern particle size analyzer. The positive electrode material was dispersed in ethanol, a dispersant, and subjected to ultrasound for 30 minutes. After that, the sample was placed in the Malvern particle size analyzer and measurement was started. In the volume-based particle size distribution of the above positive electrode material, the particle size at which the cumulative volume from the smallest diameter side reaches 50% was defined as Dv50 of the above positive electrode material.

[0093] 4. Measurement of the content of Mg, Zr, or Al elements in the positive electrode active material. After discharging the lithium-ion battery, it was disassembled, and two positions in the positive electrode active material layer (labeled Position 1 and Position 2) were randomly selected and measured as follows. 1) The positive electrode active material in the positive electrode active material layer at position 1 was obtained, and inductively coupled plasma (ICP) measurements were performed to determine the content of Mg, Zr, or Al elements in the positive electrode active material. 2) Energy-dispersive X-ray spectroscopy (EDS) was performed on the positive electrode active material layer at position 2. The measurement area was expanded 3000 times, and EDS measurements were performed on the entire area to obtain the content of Mg, Zr, or Al elements in the positive electrode active material. The maximum value of the two measurement results described above was taken as the content of Mg, Zr, or Al elements in the positive electrode active material.

[0094] 5. Measurement of the content of each component in the electrolyte. After discharging the lithium-ion battery, it was disassembled and centrifuged. Gas chromatography-mass spectrometry (GC-MS) and ion chromatography (IC) measurements were performed on the liquid obtained after centrifugation to measure each component and its content in the electrolyte.

[0095] III. Measurement Results Table 1 shows the effects of the positive electrode active material and the electrolyte on the high-temperature cycle characteristics and high-temperature interval cycle characteristics of the lithium-ion battery. Here, the median diameter Dv50 of the positive electrode active material in the examples of Table 1 is all 15 μm. The positive electrode active materials in Examples 1-2 to 1-7 are lithium cobaltate (LiCoO2) and lithium nickel 0.6 Co 0.2 Mn 0.2 O2), where the ratio of the mass of lithium cobaltate to the mass of lithium nickel cobalt manganese oxide is 3. The positive electrode active materials in other examples and Comparative Examples 1-1 to 1-10 are lithium cobaltate (LiCoO2).

[0096] As can be seen from the data in Table 1, compared with the comparative examples, the electrolyte in the examples contains EC, PC, and SN simultaneously, and their contents satisfy 1.25 ≦ k ≦ 6 and a / k ≧ 0.2. Moreover, in the positive electrode active materials in the examples, Mg, Zr, or Al elements are all doped, and their contents satisfy 0.01 ≦ x ≦ 1. In this case, the electrochemical device in the examples has a high capacity retention rate in both the cycle process and the interval cycle process at 45 °C, and has a low thickness increase rate in the interval cycle process at 45 °C.

[0097] Also, as can be seen from the comparison between Comparative Examples 1-6 and 1-7 and Example 1-1, better high-temperature characteristics can be obtained by adding SN to the electrolyte. And as can be seen from the comparison between Comparative Examples 1-8 and 1-9 and the examples, when the contents of EC, PC, and SN in the electrolyte simultaneously satisfy 1.25 ≦ k ≦ 6 and a / k ≧ 0.2, better high-temperature characteristics can be obtained.

[0098] As can be seen from the comparison between Comparative Example 1-10 and Example 1, better high-temperature characteristics can be obtained by doping the positive electrode active material with Mg compared to doping the positive electrode active material with other metal elements (e.g., Zn). Furthermore, as can be seen from Examples 1-24 and 1-25, an electrochemical apparatus with similarly excellent high-temperature characteristics can be obtained by doping the positive electrode active material with Al or Zr.

[0099] Furthermore, as can be seen from the comparison between Examples 1-30 and 1-31 and Example 1-11, if the electrochemical apparatus further satisfies 0.001 ≤ x / a ≤ 1, the high-temperature cycle characteristics and high-temperature interval cycle characteristics of the electrochemical apparatus can be further improved. As can be seen from the comparison between Example 1-32 and Examples 1-22, 1-26, and 1-27, if the electrochemical apparatus further satisfies x / k ≤ 0.4, the high-temperature cycle characteristics and high-temperature interval cycle characteristics of the electrochemical apparatus can be further improved.

[0100] [Table 1-1] [Table 1-2] [Table 1-3] Tables 2 and 3 show the effect of the median diameter Dv50 of the positive electrode active material on the high-temperature cycle characteristics and high-temperature interval cycle characteristics of lithium-ion batteries. Here, the examples in Tables 2 and 3 are all improvements based on Examples 1-10, and the only difference from Examples 1-10 is the parameters shown in Tables 2 and 3.

[0101] [Table 2] As can be seen from Table 2 above, if the electrochemical apparatus also satisfies 2 ≤ y ≤ 25 and 10 ≤ y / x ≤ 900, the high-temperature cycle characteristics and high-temperature interval cycle characteristics of the electrochemical apparatus can be further improved.

[0102] [Table 3] As can be seen from Table 3 above, if the electrochemical apparatus further satisfies 1 ≤ y / a ≤ 36, the high-temperature cycle characteristics and high-temperature interval cycle characteristics of the electrochemical apparatus can be further improved. Examples 4-1 to 4-7 in Tables 4 and 5 are improvements based on Example 1-10, Examples 4-8 and 4-9 in Table 4 are improvements based on Example 1-22, and Examples 5-1 and 5-2 in Table 5 are improvements based on Example 1-1. The specific improvement is the addition of a certain amount of LiPO2F2 to the electrolyte.

[0103] [Table 4] As can be seen from the comparison between Examples 4-1 to 4-7 and Example 1-10, both the high-temperature cycle characteristics and high-temperature interval cycle characteristics of the resulting electrochemical apparatus were improved after adding LiPO2F2 to the electrolyte. Furthermore, as can be seen from Table 4, the improvement effect on the electrochemical apparatus becomes more pronounced when the LiPO2F2 content d% satisfies 0.01 ≤ d ≤ 0.5 and 0.05 ≤ d / x ≤ 25.

[0104] [Table 5] As can be seen from the data in Table 5, if the electrochemical apparatus further satisfies the condition 0.001 ≤ d / k ≤ 0.4, the high-temperature cycle characteristics and high-temperature interval cycle characteristics of the electrochemical apparatus can be further improved.

[0105] Throughout this specification, any reference by “Example,” “Part of an Example,” “One Example,” “Another Example,” “Example,” “Specific Example,” or “Part of an Example” means that at least one example of the present invention includes the specific features, structures, materials, or properties described in that example. Therefore, any reference by “In some examples,” “In an example,” “In one example,” “In another example,” “In one example,” “In a particular example,” or “Example” found anywhere in this specification does not necessarily refer to the same example of the present invention. Furthermore, the specific features, structures, materials, or properties described herein can be combined in any preferred manner in one or more examples.

[0106] While exemplary embodiments have been described and explained, those skilled in the art should understand that the embodiments described above are not intended to limit the present invention, and that modifications, substitutions, and changes to the embodiments are permitted as long as they do not depart from the spirit, principles, and scope of the invention.

Claims

1. An electrochemical apparatus, It includes a positive electrode and an electrolyte, The electrolyte comprises ethylene carbonate, propylene carbonate, and succinonitrile. The positive electrode includes a positive electrode active material. The positive electrode active material contains metal element A, The aforementioned metal element A includes at least one of Mg, Zr, and Al. When the mass content of succinonitrile is a%, the mass content of ethylene carbonate is b%, and the mass content of propylene carbonate is c%, and k is set to k = b / c, then a and k satisfy 1.25 ≤ k ≤ 6 and a / k ≥ 0.2, and When the mass content of the metal element A is x% relative to the mass of the positive electrode active material, x satisfies 0.01 ≤ x ≤ 1. The electrochemical apparatus wherein the electrolyte further contains lithium difluorophosphate, and when the mass content of lithium difluorophosphate is d% of the mass of the electrolyte, d satisfies 0.01 ≤ d ≤ 0.5, and x and d satisfy 0.05 ≤ d / x ≤ 25.

2. The electrochemical apparatus according to claim 1, wherein x and k satisfy x / k ≤ 0.

4.

3. The electrochemical apparatus according to claim 1, wherein x and a satisfy 0.001 ≤ x / a ≤ 1.

4. The electrochemical apparatus according to claim 1, wherein the positive electrode active material contains lithium cobalt oxide.

5. The electrochemical apparatus according to claim 1, wherein the positive electrode active material comprises lithium nickel cobalt manganese oxide.

6. The positive electrode active material comprises lithium cobalt oxide and lithium nickel cobalt manganese oxide. The electrochemical apparatus according to claim 1, wherein when the ratio of the mass of lithium cobalt oxide to the mass of lithium nickel cobalt manganese oxide is g, g satisfies 1 ≤ g ≤ 9 with respect to the mass of the positive electrode active material, g satisfies 1 ≤ g ≤ 9.

7. The electrochemical apparatus according to claim 1, wherein when the median diameter Dv50 of the positive electrode active material is y μm, y satisfies 2 ≤ y ≤ 25.

8. The electrochemical apparatus according to claim 7, wherein x and y satisfy 10 ≤ y / x ≤ 900.

9. The electrochemical apparatus according to claim 7, wherein y and a satisfy 1 ≤ y / a ≤ 36.

10. The electrochemical apparatus according to claim 1, wherein k and d satisfy 0.006 ≤ d / k ≤ 0.

4.

11. An electronic apparatus comprising an electrochemical apparatus as described in any one of claims 1 to 10.

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