Electrochemical and electronic equipment

Abstract

The present invention provides an electrochemical apparatus and an electronic apparatus. The electrochemical apparatus comprises a positive electrode piece, a negative electrode piece, and an electrolyte, the electrolyte comprising additive A, which comprises at least one of the compounds represented by structural formula I and structural formula II, the positive electrode piece comprising a positive electrode material layer, the positive electrode material layer comprising manganese and iron elements, and the cycle performance and high-temperature storage performance of the electrochemical apparatus are improved by simultaneously applying the electrolyte containing additive A and the positive electrode piece containing manganese and iron elements to the electrochemical apparatus. [Formula 1] JPEG2026524579000025.jpg53170

Description

[Technical Field]

[0001] This invention claims priority to a Chinese patent application filed with the Chinese National Intellectual Property Office on June 21, 2024, with application number 202410813568.9, titled "Electrochemical and Electronic Apparatuses," the entirety of which is incorporated into this application by reference.

[0002] This invention relates to the field of electrochemistry, and more particularly to electrochemical apparatus and electronic apparatus. [Background technology]

[0003] Lithium-ion batteries have attracted widespread attention and are widely used in the energy storage field due to their characteristics such as high energy density, low maintenance costs, relatively low self-discharge, long cycle life, no memory effect, stable operating voltage, and environmental friendliness. With the increasing need for longer battery cycle life and long-term high-temperature storage in the energy storage market, there is an urgent need to develop lithium-ion energy storage batteries and electronic equipment with long cycle times and high stability. [Overview of the project]

[0004] The present invention aims to provide electrochemical and electronic devices to improve the cycle performance and high-temperature storage performance of electrochemical devices. Specific technical proposals are as follows:

[0005] In this invention, a lithium-ion battery is used as an example of an electrochemical apparatus, but the electrochemical apparatus of this invention is not limited to a lithium-ion battery.

[0006] A first aspect of the present invention provides an electrochemical apparatus comprising a positive electrode piece, a negative electrode piece, and an electrolyte. Here, the electrolyte contains additive A, which comprises at least one of a compound represented by formula I and a compound represented by formula II, and the mass percentage a of additive A is 0.05% to 4.0% of the total mass of the electrolyte.

Chem.

[0007] Here, R1 to R9 are each independently selected from a hydrogen atom, a fluorine atom, an unsubstituted or fluorine-substituted C1-C5 alkyl group, an unsubstituted or fluorine-substituted C2-C5 alkenyl group, or an unsubstituted or fluorine-substituted C2-C5 alkynyl group, and the fluorine substitution may be a full substitution or a partial substitution. The positive electrode sheet includes a positive electrode material layer, the positive electrode material layer contains a manganese element and an iron element, and with respect to the total mass of the positive electrode material layer, the mass percentage of the manganese element is W Mn When it is set as Mn and a, 0.43 ≦ 100a / W Mn ≦ 170.94 is satisfied, and preferably 0.86 ≦ 100a / W Mn ≦ 34.21 is satisfied. By adjusting the ratio 100a / W Mn of the mass percentage a of the additive A to the mass percentage W Mn of the manganese element within the scope of the present invention, it is advantageous for the synergistic effect of the additive A and the manganese element in the positive electrode material layer to be exerted, and the uneven deposition of Mn 3+ in the negative electrode can be effectively alleviated. Thereby, the kinetic performance of the electrochemical device can be improved, and the cycle performance and high-temperature storage performance of the electrochemical device can be improved.

[0008] In one embodiment of the present invention, the electrolytic solution contains an additive B, the additive B contains at least one of a compound represented by formula III, a compound represented by formula IV, a compound represented by formula V, and a compound represented by formula VI, and with respect to the total mass of the electrolytic solution, the mass percentage b of the additive B is 0.05% to 4.0%.

Chem.

[0009] Here, R 11 , R 12 , R 16 , R 19Each of these is independently selected from a hydrogen atom, a fluorine atom, an unsubstituted or fluorine-substituted C1-C5 alkyl group, an unsubstituted or fluorine-substituted C2-C5 alkenyl group, or an unsubstituted or fluorine-substituted C2-C5 alkynyl group, R 10 , R 15 , R 18 Each of these is independently selected from an oxygen atom, a methylene group, an ethylene group, a methyleneoxy group, and an ethyleneoxy group, and R 13 , R 14 Each is independently selected from unsubstituted or fluorine-substituted C1-C5 alkylene groups, R 17 , R 20 Each of these groups is independently selected from an unsubstituted or fluorine-substituted C1-C8 alkylene group, an unsubstituted or fluorine-substituted C2-C8 alkenylene group, or an unsubstituted or fluorine-substituted C2-C8 alkylylene group, and the fluorine substitution may be total substitution or partial substitution.

[0010] In one embodiment of the present invention, the mass percentage of iron element is set to W with respect to the total mass of the positive electrode material layer. Fe In that case, W Mn , W Fe And b is 0.13 ≤ 100b / (W Fe +W Mn ) ≤ 11.41, preferably 0.14 ≤ 100b / (W Fe +W Mn ) ≤ 5.49 satisfies. 100b / (W Fe +W Mn By adjusting the value of ) within the above range, it is advantageous for constructing a stable CEI film, improving kinetic performance and reducing electrolyte side reactions, thereby improving the cycle performance and high-temperature storage performance of lithium-ion batteries.

[0011] In one embodiment of the present invention, the compound represented by formula I or the compound represented by formula II includes at least one of the compounds represented by the following formulas I-1 to II-7. [ka]

[0012] In one embodiment of the present invention, the compound represented by formula III, the compound represented by formula IV, the compound represented by formula V, or the compound represented by formula VI includes at least one of the compounds represented by the following formulas III-1 to VI-7. [ka] [ka] [ka] [ka]

[0013] In one embodiment of the present invention, the ratio of the mass percentages of additive A to additive B, a / b, satisfies 0.1 ≤ a / b ≤ 10. By adjusting the ratio of the mass percentages of additive A to additive B, a / b, to within the above range, the volume expansion of the lithium-ion battery during the cycle process can be reduced, the consumption of active lithium can be reduced, and the cycle performance of the lithium-ion battery can be improved.

[0014] In one embodiment of the present invention, the positive electrode material layer comprises a first positive electrode material and a second positive electrode material, wherein the first positive electrode material is LiFePO4 and the second positive electrode material is a lithium manganese composite oxide, and the chemical formula of the lithium manganese composite oxide is Li 1+r Mn 1-p T p O 2-s M swhere, in the formula, -0.1 < r < 0.2, 0 ≤ p < 0.2, 0 ≤ s < 0.2, T contains at least one of Co, Ni, Ti, Zn, Mg, Al, V, Cr and Zr, and M contains at least one of S, N, F, Cl and Br. The introduction of the first positive electrode material is advantageous for stably releasing and occluding lithium ions during the charging and discharging cycles of the lithium ion battery, and the introduction of the second positive electrode material plays a role in lithium replenishment to the positive electrode and can improve the cycle performance of the lithium ion battery.

[0015] In one embodiment of the present invention, with respect to the total mass of the positive electrode material layer, the mass percentage W Mn of the manganese element is 2.34% to 11.69%, and the mass percentage W Fe of the iron element is 27.05% to (32.71%, and the ratio W Mn / W Fe of the mass percentages of the manganese element and the iron element is 0.072 to 0.432. By adjusting the ratio W Mn / W Fe within the above range, the kinetic performance can be improved, the resistance of the battery can be reduced, and the cycle performance and high-temperature storage performance of the lithium ion battery can be improved.

[0016] In one embodiment of the present invention, the positive electrode material layer has a first diffraction peak within the range of 18° to 19° and a second diffraction peak within the range of 15° to 16° in the XRD diffraction pattern (Cu target, Kα line) at 3.6V. Having the first diffraction peak and the second diffraction peak is beneficial for relatively high stability of the positive electrode active material positive electrode material layer and for improving the cycle performance of the lithium ion battery.

[0017] In one embodiment of the present invention, the electrolyte contains additive C, which comprises at least one of lithium difluorophosphate (LiPO2F2), lithium difluoro(oxalato)borate (LiDFOB), lithium tetrafluoroborate (LiBF4), and lithium bis(oxalato)borate (LiBOB), and the mass percentage c of additive C is 0.01% to 2% of the mass of the electrolyte. By adjusting the mass percentage c of additive C to the above range, the interfacial resistance is reduced, the ionic conductivity of the positive electrode CEI is improved, and the rate performance and cycle performance of the lithium-ion battery are improved.

[0018] A second aspect of the present invention provides an electronic apparatus including an electrochemical apparatus provided in the first aspect of the present invention. Beneficial effects of the present invention:

[0019] The present invention provides an electrochemical apparatus and an electronic apparatus. The electrochemical apparatus comprises a positive electrode piece, a negative electrode piece, and an electrolyte. The electrolyte contains additive A, which is a nitrogen-containing heterocyclic compound. The positive electrode piece comprises a positive electrode material layer, and the positive electrode material layer contains manganese. The mass percentage of additive A is a, and the mass percentage of manganese is W. Mn and 100a / W Mn By adjusting this within the scope of the present invention, it is advantageous for the synergistic effect between additive A and the manganese element in the positive electrode material layer, and Mn in the negative electrode. 3+ By effectively reducing the uneven deposition of material, the dynamic performance of the electrochemical apparatus can be improved, as can the cycle performance and high-temperature storage performance of the electrochemical apparatus.

[0020] Of course, implementing any of the products or methods of the present invention does not necessarily mean achieving all of the advantages described above simultaneously. [Modes for carrying out the invention]

[0021] The following describes the technical concepts in the embodiments of the present invention clearly and completely. Clearly, the embodiments described herein represent only a portion of the embodiments of the present invention and do not encompass all embodiments. All other embodiments that those skilled in the art can obtain based on the present invention are within the scope of protection of the present invention.

[0022] In the specific embodiments of the present invention, a lithium-ion battery is used as an example of an electrochemical apparatus, but the electrochemical apparatus of the present invention is not limited to a lithium-ion battery.

[0023] By combining different positive electrode materials and utilizing the charge-discharge curve characteristics of each material, the number of active lithium atoms can be increased, thereby improving the battery's lifespan. However, using a combination of different materials places a higher demand on compatibility with the electrolyte. To stabilize high-value transition metals and reduce oxidative decomposition of the electrolyte on the positive electrode side and the breakdown of transition metals against the negative electrode during full charge, the present invention improves the lifespan of lithium-ion batteries by introducing a new positive electrode mixed material into lithium-ion batteries. Furthermore, by introducing a new additive into the electrolyte of lithium-ion batteries and adjusting the type and amount of the additive according to different transition metals, the invention achieves the goals of reduced resistance and a longer cycle life of lithium-ion batteries, while also significantly improving the high-temperature storage performance of the batteries.

[0024] A first aspect of the present invention provides an electrochemical apparatus comprising a positive electrode piece, a negative electrode piece, and an electrolyte. Here, the electrolyte contains additive A, which is selected from nitrogen-containing heterocyclic compounds, and additive A comprises at least one of a compound represented by formula I and a compound represented by formula II, and the mass percentage a of additive A is 0.05% to 4.0% of the total mass of the electrolyte. [ka]

[0025] Here, R1 to R9 are each independently selected from a hydrogen atom, a fluorine atom, an unsubstituted or fluorine-substituted C1 to C5 alkyl group, an unsubstituted or fluorine-substituted C2 to C5 alkenyl group, or an unsubstituted or fluorine-substituted C2 to C5 alkynyl group. Fluorine substitution may be total substitution or partial substitution. The positive electrode piece includes a positive electrode material layer, the positive electrode material layer includes manganese and iron elements, and the mass percentage of the manganese element relative to the total mass of the positive electrode material layer is W Mn In that case, W Mn And a is 0.43 ≤ 100a / W Mn The value satisfies ≤170.94, and preferably 0.86 ≤ 100 a / W. Mn It satisfies ≤ 34.21.

[0026] For example, the mass percentage a of additive A may be in the range of 0.05%, 0.1%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, or any two of these values. By adjusting the mass percentage a of additive A to within the above range, the amount of Mn at the negative electrode can be increased. 3+ This can reduce uneven deposition, improve kinetic performance, and enhance the cycle performance of lithium-ion batteries.

[0027] For example, the ratio of the mass percentage a of additive A to the mass percentage of manganese element is 100 a / W. Mn The range may be 0.43, 1, 10, 20, 30, 50, 70, 90, 110, 130, 150, 170.94, or any two of these numbers. Ratio 100 a / w Mn If the ratio is too high, for example, exceeding the upper limit of the present invention, a relatively large amount of additive A increases the interfacial resistance on one side of the negative electrode, increasing the side reactions of the additive itself in the electrolyte, thereby reducing the kinetic performance, high-temperature storage performance, and cycle performance of the electrochemical apparatus. Ratio 100 a / W Mn If it is too small, for example, below the lower limit of the present invention, relatively small amounts of additive A, Mn 3+The non-uniform deposition of additive A cannot be effectively reduced, and the structure of graphite in the negative electrode fragment is destroyed, leading to a decrease in the kinetic performance, high-temperature storage, and cycle performance of the electrochemical apparatus. (A mass percentage a of additive A and W mass percentage of manganese element) Mn The ratio is 100A / W. Mn By adjusting this within the scope of the present invention, it is advantageous for the synergistic effect between additive A and the manganese element in the positive electrode material layer, and Mn in the negative electrode. 3+ This effectively reduces uneven deposition, thereby improving the dynamic performance of the electrochemical apparatus and enhancing its cycle performance and high-temperature storage performance.

[0028] In one embodiment of the present invention, the electrolyte contains additive B, which is selected from sulfonic acid ester compounds or sulfate ester compounds, and additive B contains at least one of the compounds represented by formula III, formula IV, formula V, and formula VI, and the mass percentage b of additive B is 0.05% to 4.0% of the total mass of the electrolyte. [ka]

[0029] Here, R 11 , R 12 , R 16 , R 19 Each of these is independently selected from a hydrogen atom, a fluorine atom, an unsubstituted or fluorine-substituted C1-C5 alkyl group, an unsubstituted or fluorine-substituted C2-C5 alkenyl group, or an unsubstituted or fluorine-substituted C2-C5 alkynyl group, R 10 , R 15 , R 18 Each of these is independently selected from an oxygen atom, a methylene group, an ethylene group, a methyleneoxy group, or an ethyleneoxy group, and R 13 , R 14 Each is independently selected from unsubstituted or fluorine-substituted C1-C5 alkylene groups, R 17 , R 20Each of these groups is independently selected from an unsubstituted or fluorine-substituted C1-C8 alkylene group, an unsubstituted or fluorine-substituted C2-C8 alkenylene group, or an unsubstituted or fluorine-substituted C2-C8 alkylylene group, and the fluorine substitution may be total substitution or partial substitution.

[0030] For example, the mass percentage b of additive B may be in the range of 0.05%, 0.1%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, or any two of these values. By adjusting the mass percentage b of additive B to within the above range, CEI stability can be improved, and Fe 3+ and Mn 3+ This reduces gas generation due to oxidation, improves kinetic performance, and enhances the cycle performance and high-temperature storage performance of lithium-ion batteries.

[0031] In one embodiment of the present invention, the mass percentage of iron element is set to W with respect to the total mass of the positive electrode material layer. Fe In that case, W Mn , W Fe And b is 0.13 ≤ 100b / (W Fe +W Mn ) ≤ 11.41, preferably 0.14 ≤ 100b / (W Fe +W Mn ) ≤ 5.49 is satisfied. For example, 100b / (W Fe +W Mn The value of ) may be 0.13, 1, 3, 5, 7, 9, 11.41, or any two of these numbers. 100b / (W Fe +W Mn By adjusting the value of ) within the above range, it is advantageous for the cooperation between the additive and the cathode, and advantageous for the construction of a stable CEI film, Fe 3+ and Mn 3+ This reduces gas generation due to oxidation, improves kinetic performance, and reduces side reactions in the electrolyte, thereby improving the cycle performance and high-temperature storage performance of lithium-ion batteries.

[0032] In one embodiment of the present invention, the compound represented by formula I or the compound represented by formula II includes at least one of the compounds represented by the following formulas I-1 to II-7. [ka]

[0033] In one embodiment of the present invention, the compound represented by formula III, the compound represented by formula IV, the compound represented by formula V, or the compound represented by formula VI includes at least one of the compounds represented by the following formulas III-1 to VI-7. [ka] [ka] [ka] [ka]

[0034] In one embodiment of the present invention, the mass percentage ratio a / b of additive A to additive B satisfies 0.1 ≤ a / b ≤ 10. For example, the mass percentage ratio a / b of additive A to additive B may be in the range of 0.1, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, or any two of these values. By adjusting the mass percentage ratio a / b of additive A to additive B within the above range, a uniform and appropriate ratio of organic to inorganic components can be obtained for SEI / CEI, thereby reducing the volume expansion of the lithium-ion battery during the cycle, reducing the consumption of active lithium, and improving the cycle performance of the lithium-ion battery.

[0035] In one embodiment of the present invention, the positive electrode material layer comprises a first positive electrode material and a second positive electrode material, wherein the first positive electrode material is LiFePO4 and the second positive electrode material is a lithium manganese composite oxide, and the chemical formula of the lithium manganese composite oxide is Li 1+rMn 1-p T p O 2-s is Ms. In the formula, -0.1 < r < 0.2, 0 ≤ p < 0.2, 0 ≤ s < 0.2, T contains at least one of Co, Ni, Ti, Zn, Mg, Al, V, Cr, and Zr, and M contains at least one of S, N, F, Cl, and Br. The introduction of the first positive electrode material is advantageous for stably discharging and occluding lithium ions during the charging and discharging cycles of the lithium-ion battery, and the introduction of the second positive electrode material can exert the effect of lithium replenishment to the positive electrode and improve the cycle performance of the lithium-ion battery.

[0036] In one embodiment of the present invention, with respect to the total mass of the positive electrode material layer, the mass percentage W Mn of the manganese element is 2.34% to 11.69%, and the mass percentage W Fe of the iron element is 27.05% to 32.71%. The ratio W Mn / W Fe of the mass percentages of the manganese element and the iron element is 0.072 to 0.432. For example, the mass percentage W Mn of the manganese element may be 2.34%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 11.69% or a range consisting of any two of these numerical values. The mass percentage W Fe of the iron element may be 27.05%, 28%, 29%, 30%, 31%, 32%, 32.71% or a range consisting of any two of these numerical values. The ratio W Mn / W Fe of the mass percentages of the manganese element and the iron element may be 0.072, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.432 or a range consisting of any two of these numerical values. Without being limited to any theory, the inventor of the present invention adjusts the ratio W Mn / W Fe within the above range, thereby significantly improving the kinetic performance, improving the cycle performance and the generation of gas due to high-temperature storage, and Mn 3+We found that this can reduce the leaching and deposition of certain substances, lower the battery's resistance, and improve the cycle performance and high-temperature storage performance of lithium-ion batteries.

[0037] In one embodiment of the present invention, the positive electrode material layer has a first diffraction peak in the range of 18° to 19° and a second diffraction peak in the range of 15° to 16° in the XRD diffraction pattern (Cu target, Kα line) at 3.6V. The first and second diffraction peaks correspond to the diffraction peaks of the (111) and (010) crystal planes, respectively. The lithium ion diffusion coefficients of the corresponding (111) and (010) crystal planes are larger, resulting in relatively higher stability of the positive electrode active material layer, which is advantageous for improving the cycle performance of the lithium-ion battery.

[0038] In one embodiment of the present invention, the electrolyte contains additive C, which comprises at least one of lithium difluorophosphate (LiPO2F2), lithium difluoro(oxalato)borate (LiDFOB), lithium tetrafluoroborate (LiBF4), and lithium bis(oxalato)borate (LiBOB), and the mass percentage c of additive C is 0.01% to 2% of the mass of the electrolyte. For example, the mass percentage c of additive C may be in the range of 0.01%, 0.1%, 0.3%, 0.5%, 0.6%, 0.7%, 0.9%, 1.1%, 1.3%, 1.5%, 1.7%, 1.9%, 2%, or any two of these values. Without regard to any theory, the inventors of the present invention have found that adjusting the mass percentage c of additive C within the above range is advantageous for forming a large amount of phosphides and borides on the positive electrode side, thereby reducing interfacial resistance, improving the ionic conductivity of the positive electrode CEI, and improving the rate performance and cycle performance of the lithium-ion battery.

[0039] In the present invention, the electrolyte further comprises a lithium salt, and the present invention is not particularly limited to the lithium salt, and any lithium salt known in the art may be used as long as the object of the present invention is achieved. For example, the lithium salt may be selected from at least one of LiPF6, LiBF4, LiAsF6, LiClO4, LiB(C6H5)4, LiCH3SO3, LiCF3SO3, LiN(SO2CF3)2, LiC(SO2CF3)3, and LiPO2F2. The mass percentage of the lithium salt relative to the mass of the electrolyte may be 8% to 15%, and for example, the mass percentage of the lithium salt may be in the range of 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, or any two of these values. The present invention is not particularly limited to the non-aqueous solvent, and for example, the non-aqueous solvent may include, but is not limited to, at least one of carbonate compounds, carboxylic acid ester compounds, ether compounds, and other organic solvents.

[0040] The above-mentioned carbonate compound may include, but is not limited to, at least one of a linear carbonate compound, a cyclic carbonate compound, and a fluorocarbonate compound. The above-mentioned linear carbonate compound may include, but is not limited to, at least one of dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methylpropyl carbonate (MPC), ethylpropyl carbonate (EPC), and methyl ethyl carbonate (MEC). The above-mentioned cyclic carbonate may include, but is not limited to, at least one of ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), and vinylethylene carbonate (VEC). The fluorocarbonate compound may include, but is not limited to, at least one of fluoroethylene carbonate (FEC), 1,2-difluoroethylene carbonate, 1,1-difluoroethylene carbonate, 1,1,2-trifluoroethylene carbonate, 1,1,2,2-tetrafluoroethylene carbonate, 1-fluoro-2-methylethylene carbonate, 1-fluoro-1-methylethylene carbonate, 1,2-difluoro-1-methylethylene carbonate, 1,1,2-trifluoro-2-methylethylene carbonate, and trifluoromethylethylene carbonate. The carboxylic acid ester compound may include, but is not limited to, at least one of methyl formate, methyl acetate, ethyl acetate, n-propyl acetate, t-butyl acetate, methyl propionate, ethyl propionate, propyl propionate, γ-butyrolactone, decanolactone, valerolactone, and caprolactone. The above ether compounds may include, but are not limited to, at least one of dibutyl ether, tetraethylene glycol dimethyl ether, diethylene glycol dimethyl ether, 1,2-dimethoxyethane, 1,2-diethoxyethane, 1-ethoxy-1-methoxyethane, 2-methyltetrahydrofuran, and tetrahydrofuran.The other organic solvents listed above may include, but are not limited to, at least one of dimethyl sulfoxide, 1,2-dioxolane, sulfolane, methylsulfolane, 1,3-dimethyl-2-imidazolidinone, N-methyl-2-pyrrolidone, dimethylformamide, acetonitrile, trimethyl phosphate, triethyl phosphate, and trioctyl phosphate.

[0041] The present invention does not have any particular limitations on the content of the non-aqueous solvent in the electrolyte, as long as the objective of the present invention is achieved. For example, the mass percentage of the non-aqueous solvent relative to the mass of the electrolyte is 75% to 91.95%, and for example, the mass percentage of the non-aqueous solvent may be in the range of 75%, 80%, 85%, 90%, 91.95%, or any two of these values.

[0042] In one embodiment of the present invention, the electrolyte may contain additive A, a lithium salt, and a non-aqueous solvent, wherein the mass percentages of additive A and the lithium salt are as described above, and the mass percentage of the non-aqueous solvent is 81% to 91.95%. A lithium-ion battery containing the above electrolyte has good cycle performance and high-temperature storage performance.

[0043] In one embodiment of the present invention, the electrolyte may contain additive A, additive B, a lithium salt, and a non-aqueous solvent, wherein the mass percentages of additive A, additive B, and lithium salt are as described above, and the mass percentage of the non-aqueous solvent is 77% to 91.9%. A lithium-ion battery containing the above electrolyte has good cycle performance and high-temperature storage performance.

[0044] In one embodiment of the present invention, the electrolyte may contain additive A, additive C, a lithium salt, and a non-aqueous solvent, wherein the mass percentages of additive A, additive C, and lithium salt are as described above, and the mass percentage of the non-aqueous solvent is 79% to 91.94%. A lithium-ion battery containing the above electrolyte has good cycle performance and high-temperature storage performance.

[0045] In one embodiment of the present invention, the electrolyte may contain additive A, additive B, additive C, a lithium salt, and a non-aqueous solvent, wherein the mass percentages of additive A, additive B, additive C, and lithium salt are as described above, and the mass percentage of the non-aqueous solvent is 75% to 91.8%. A lithium-ion battery containing the above electrolyte has good cycle performance and high-temperature storage performance.

[0046] In the present invention, the positive electrode piece includes a positive electrode current collector and a positive electrode material layer installed on at least one surface of the positive electrode current collector. The "positive electrode material layer installed on at least one surface of the positive electrode current collector" means that the positive electrode material layer may be installed on one surface of the positive electrode current collector in its thickness direction, or on both surfaces of the positive electrode current collector in its thickness direction. Here, "surface" may refer to the entire surface of the positive electrode current collector, or to a part of the surface of the positive electrode current collector, and the present invention is not particularly limited as long as the objective of the present invention is achieved.

[0047] In the present invention, the positive electrode current collector is not particularly limited and only needs to be able to achieve the objectives of the present invention. For example, it may include aluminum foil, aluminum alloy foil, or composite current collectors (e.g., aluminum-carbon composite current collectors).

[0048] In the present invention, the positive electrode material layer may further contain a conductive agent and a binder, and the present invention is not particularly limited in terms of the type of conductive agent and binder, as long as the object of the present invention is achieved. The present invention is not particularly limited in terms of the mass ratio of the positive electrode active material, conductive agent and binder in the positive electrode material layer, and those skilled in the art can select them as needed, as long as the present invention is achieved.

[0049] The present invention is not particularly limited to the binder, as long as it can achieve the objectives of the present invention. For example, the binder may include, but is not limited to, an adhesive polymer. The adhesive polymer includes, for example, at least one of polyvinylidene fluoride, polytetrafluoroethylene, polyolefins, sodium carboxymethylcellulose, lithium carboxymethylcellulose, modified polyvinylidene fluoride, modified SBR rubber, and polyurethane. Here, the polyolefin as a binder includes at least one of polyethylene, polypropylene, polyalkenyl ester, polyalkenyl alcohol, and polyacrylic acid.

[0050] The present invention is not particularly limited to conductive agents, and only those that can achieve the objectives of the present invention are acceptable. For example, the conductive agent may include, but is not limited to, carbon-based materials, metallic materials, conductive polymers, or mixtures thereof. Carbon-based materials include natural graphite, artificial graphite, carbon black, acetylene black, Ketchemb black, or carbon fiber. Examples of metallic materials include metal powders or metal fibers such as copper, nickel, aluminum, and silver. Conductive polymers include polyphenylene derivatives. The present invention does not have any particular limitations on the thickness of the positive electrode current collector and the positive electrode material layer, as long as the objective of the present invention can be achieved. For example, the thickness of the positive electrode current collector is 5 μm to 20 μm, and the thickness of the positive electrode material layer on one side is 30 μm to 120 μm.

[0051] Optionally, the positive electrode piece may further include a conductive layer located between the positive electrode current collector and the positive electrode material layer. The composition of the conductive layer is not particularly limited and may be a conductive layer commonly used in the art. The conductive layer includes a conductive agent and a binder. In the present invention, the conductive agent and binder in the conductive layer are not particularly limited and may be, for example, at least one of the above-mentioned conductive agent and binder.

[0052] In the present invention, the electrochemical apparatus further includes a separator. The present invention is not particularly limited to the separator, as long as it can achieve the objectives of the present invention. For example, the material of the separator may include, but is not limited to, at least one of polyethylene (PE), polyolefin (PO) mainly composed of polypropylene (PP), polyester (e.g., polyethylene terephthalate (PET) film), cellulose, polyimide (PI), polyamide (PA), spandex, and aramid. The type of separator may include at least one of woven film, nonwoven film, microporous film, composite film, compressed film, and spun film.

[0053] In some embodiments of the present invention, the separator may include a base layer and a surface treatment layer. The base layer may be a nonwoven fabric, film, or composite film having a porous structure, and the material of the base layer may include at least one of polyethylene, polypropylene, polyethylene terephthalate, and polyimide. Optionally, a polypropylene porous film, a polyethylene porous film, a polypropylene nonwoven fabric, a polyethylene nonwoven fabric, or a polypropylene-polyethylene-polypropylene porous composite film may be used.

[0054] Optionally, a surface treatment layer is provided on at least one surface of the substrate 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.

[0055] In some embodiments of the present invention, the inorganic layer comprises inorganic particles and a binder. The present invention is not particularly limited to the inorganic particles, and for example, the inorganic particles may comprise at least one of aluminum oxide, silicon oxide, magnesium oxide, titanium oxide, hafnium dioxide, tin oxide, cerium dioxide, nickel oxide, zinc oxide, calcium oxide, zirconium oxide, yttrium oxide, silicon carbide, boehmite, aluminum hydroxide, magnesium hydroxide, calcium hydroxide, and barium sulfate. The present invention is not particularly limited to the binder, and for example, the binder may comprise at least one of the above binders. In some embodiments of the present invention, the polymer layer comprises a polymer, the polymer material comprising at least one of polyamide, polyacrylonitrile, acrylate polymer, polyacrylic acid, polyacrylate, polyvinylpyrrolidone, polyvinyl ether, and polyvinylidene fluoride, and poly(vinylidene fluoride-hexafluoropropylene).

[0056] In some embodiments of the present invention, the inorganic layer may further contain a thickening agent and a wetting agent, and the present invention is not particularly limited to the type of thickening agent and wetting agent, as long as the object of the present invention is achieved. For example, the thickening agent may contain, but is not limited to, at least one of sodium carboxymethylcellulose and lithium carboxymethylcellulose. The wetting agent may contain, but is not limited to, at least one of dimethylsiloxane, sodium dodecyl sulfate, trialkyl phosphate, methyl decanoate, and dodecyl acetate.

[0057] In the present invention, the thickness of the separator is not particularly limited and only needs to be such that the objective of the present invention can be achieved. For example, the thickness of the separator may be 4 μm to 30 μm.

[0058] In the present invention, the electrochemical device further includes a negative electrode sheet, and the negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer disposed on at least one surface of the negative electrode current collector. The above-mentioned "negative electrode active material layer disposed on at least one surface of the negative electrode current collector" means that the negative electrode active material layer may be disposed on one surface in the thickness direction of the negative electrode current collector, or may be disposed on both surfaces in the thickness direction of the negative electrode current collector. Here, the "surface" may be the entire area of the surface of the negative electrode current collector, or may be a partial area of the surface of the negative electrode current collector. The present invention is not particularly limited as long as the object of the present invention can be achieved.

[0059] In the present invention, the negative electrode current collector is not particularly limited as long as the object of the present invention can be achieved. For example, it may include a copper foil, a copper alloy foil, a nickel foil, a stainless steel foil, a titanium foil, a foamed nickel, a foamed copper, or a composite current collector. Exemplarily, the composite current collector may be a lithium copper composite current collector, a carbon copper composite current collector, a nickel copper composite current collector, a titanium copper composite current collector, etc.

[0060] The negative electrode active material layer of the present invention contains a negative electrode active material. The present invention is not particularly limited with respect to the type of the negative electrode active material as long as the object of the present invention can be achieved. For example, the negative electrode active material may include at least one of natural graphite, artificial graphite, mesocarbon microbeads (MCMB), hard carbon, soft carbon, silicon, a silicon-carbon composite, SiO x (0 < x < 2), a Li-Sn alloy, a Li-Sn-O alloy, Sn, SnO, SnO2, Li4Ti5O which is lithium titanate having a spinel structure 12 , a Li-Al alloy, and metallic lithium.

[0061] The present invention is not particularly limited with respect to the thickness of the negative electrode current collector and the negative electrode active material layer as long as the object of the present invention can be achieved. For example, the thickness of the negative electrode current collector is 4 μm to 12 μm, and the thickness of the negative electrode active material layer is 30 μm to 130 μm.

[0062] In some embodiments of the present invention, the negative electrode active material layer may further contain a conductive agent and a binder, and the present invention is not particularly limited to the type of conductive agent and binder, as long as the object of the present invention is achieved. For example, the binder may include, but is not limited to, polyvinyl alcohol, hydroxypropyl cellulose, diacetylcellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene oxide-containing polymers, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, acrylic acid (esterified) styrene-butadiene rubber, epoxy resins, and nylon. The conductive agent may include, but is not limited to, carbon-based materials, metallic materials, conductive polymers, and mixtures thereof. Carbon-based materials are selected from natural graphite, artificial graphite, carbon black, acetylene black, Ketchemba black, carbon fiber, and any combination thereof; metallic materials are selected from metal powders, metal fibers, copper, nickel, aluminum, and silver; and conductive polymers are polyphenylene derivatives. The present invention does not particularly limit the mass ratio of the negative electrode material, conductive agent, and binder in the negative electrode active material layer, and those skilled in the art can select them as needed, as long as the present invention can be achieved.

[0063] The electrochemical apparatus further includes a case for housing a positive electrode, a separator, a negative electrode, and an electrolyte, as well as other components known in the field of electrochemical apparatus, and the present invention does not limit the above-mentioned other components. The present invention is not particularly limited to the case, and any case known in the art may be used as long as it achieves the purpose of the present invention. For example, the case may be a rigid case or a flexible case. The material of the rigid case may be metal, and the present invention does not limit the type of metal, and any metal rigid case known in the art may be used as long as it achieves the purpose of the present invention. The flexible case may be a metal laminate film such as an aluminum laminate film or a steel laminate film.

[0064] The preparation process for the electrochemical apparatus of the present invention is well known to those skilled in the art, and the present invention is not particularly limited. For example, the preparation process for the electrochemical apparatus may include, but is not limited to, the steps of stacking a positive electrode piece, a separator, and a negative electrode piece in this order, performing operations such as winding and folding as necessary to obtain a wound electrode assembly, placing the electrode assembly in a case, injecting electrolyte into the case and sealing it, and obtaining the electrochemical apparatus. Alternatively, the process may include, but is not limited to, stacking a positive electrode piece, a separator, and a negative electrode piece in this order, fixing the four corners of the entire stacked structure with adhesive tape to obtain a stacked electrode assembly, placing the electrode assembly in a case, injecting electrolyte into the case and sealing it, and obtaining the electrochemical apparatus. Furthermore, in order to prevent pressure rise inside the electrochemical apparatus and overcharging / discharging, an overcurrent prevention element, lead plates, etc., may be provided in the case as necessary.

[0065] A second aspect of the present invention provides an electronic apparatus including an electrochemical apparatus provided in the first aspect of the present invention.

[0066] The electronic devices of the present invention are not limited to those described herein and may be any electronic devices known in the prior art. In some embodiments, the electronic devices may include, but are not limited to, laptop computers, pen-input computers, mobile computers, e-book players, mobile phones, mobile fax machines, portable copiers, mobile printers, headphone stereos, video recorders, LCD televisions, handheld vacuum cleaners, portable CD players, MiniDiscs, 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. Examples

[0067] The embodiments of the present invention will be described in more detail below with reference to examples and comparative examples. Each measurement and evaluation is performed as follows. Unless otherwise specified, "parts" and "%" are based on mass. Measurement method and apparatus Measurement of Mn and Fe element content

[0068] A lithium-ion battery was discharged to 2.5V at 0.5C, then disassembled to remove the positive electrode piece. The positive electrode piece was cut into 10 small discs with a diameter of 16mm, and the positive electrode material layer was scraped off from the positive electrode current collector of one of the small discs with a knife to obtain a powder. 0.2 g of powder was weighed, decomposed in 10 mL of aqua regia, diluted to 100 mL with deionized water in a volumetric flask to a fixed volume, and then measured using an inductively coupled plasma analyzer (ICP, model: AVIO-200) with a radio frequency generator (RF) frequency of 40.68 MHz, argon gas secondary pressure of 0.6 MPa, radio frequency output of 1400 W, and pump speed of 1.0 mL / min. Qualitative analysis was then performed based on the spectral line wavelengths of the sample, and quantitative calculations were performed using the proportional relationship between spectral line intensity and concentration to determine the content of each element. The average value of the content of each element obtained from the 10 small discs was calculated and used as the mass percentage of iron and manganese in the positive electrode material layer. Measurement of electrolyte components

[0069] A lithium-ion battery was discharged to 2.5V at 0.5C, then disassembled to remove the positive and negative electrode pieces. The positive and negative electrode pieces were placed in a centrifuge tube and centrifuged to obtain the electrolyte. The centrifuged electrolyte was then collected, and the percentage content of additives A and B was detected using a gas chromatograph-mass spectrometer (GC-MS). XRD measurement

[0070] 1.0 g of each binder sample prepared in each example and comparative example was weighed, poured into the groove of a glass sample rack, and flattened by compressing with a glass plate. Then, it was measured using an X-ray diffractometer (model: Bruker, D8) according to JJS K 0131-1996 "General Rules for X-ray Diffraction Analysis," with a measurement voltage of 3.6 V, a current of 30 mA, a scanning angle range of 10° to 90°, a scanning step width of 0.0167°, and a time set for each step width of 0.24 s to obtain the XRD diffraction pattern of the positive electrode material layer. Measurement of cycle performance

[0071] Under conditions of 45°C, a lithium-ion battery is charged to 3.6V at 1C, then charged at a constant voltage of 0.05C at 3.6V, and then discharged to 2.5V at a current of 1C. This cycle is repeated 3000 times. If the discharge capacity after one cycle is defined as the initial discharge capacity C0 and the discharge capacity after 3000 cycles is defined as C1, then the cycle capacity retention rate (%) = C1 / C0 × 100%. Measurement of high-temperature storage performance

[0072] A lithium-ion battery was charged at 25°C with a constant current of 0.5C to 3.6V, then charged at a constant voltage of 0.05C. The thickness of the lithium-ion battery was measured and defined as d0. The battery was then left in a 60°C oven for 180 days, and the thickness at this time was recorded and defined as d. The thickness expansion rate (%) of the lithium-ion battery after high-temperature storage at 60°C is (d-d0) / d0 × 100%. Measurement of resistance at 50% charge

[0073] At a temperature of 25°C, the lithium-ion battery was discharged at a current of 0.5C until 2.5V, rested for 5 minutes, then charged at a current of 0.5C until 3.6V, and charged at a constant voltage of 3.6V until 0.025C. After resting for 5 minutes, it was discharged at a current of 0.1C until 2.5V, and the discharge capacity at this time was designated as C1. It was charged until 3.6V with a capacity of 0.5C1, charged at a constant voltage of 3.6V until 0.025C1, rested for 5 minutes, discharged at a current of 0.1C1 for 5 hours, and the voltage of the battery at this time was designated as V1. Then, it was discharged at a current of 1C for 1 second, and the voltage at the end of discharge was designated as V2. The calculation formula for the resistance at 50% charge state is: Resistance at 50% charge state (mΩ) = (V1 - V2) / (1C - 0.1C Measurement of rate performance

[0074] [[ID=I5]] Under the condition of 25°C, the lithium-ion battery was charged at 0.3C until 3.6V, charged at a constant voltage of 3.6V until 0.05C, rested for 5 minutes, then discharged at a current of 0.3C until 2.5V, and the discharge capacity C (放電レート) Recorded, the discharge rates in the above process were sequentially adjusted to 0.5C, 1.0C, and 2.0C, each repeated once, and the rate discharge capacity retention rate was calculated. Rate discharge capacity retention rate (%) = C (2.0C) (0.3C) / C (0.3C) × 100%. Example 1-1 <Preparation of positive electrode sheet>

[0075] LiFePO4, the first positive electrode material, LiMnO2, the second positive electrode material, conductive carbon black, and PVDF, the binder, were mixed according to a mass ratio of 86.5:10:2.0:1.5, N-methylpyrrolidone (NMP) was added, and stirred to mix uniformly to obtain a positive electrode slurry with a solid content of 70wt%. The positive electrode slurry was uniformly coated on one surface of an aluminum foil, which was a positive electrode current collector with a thickness of 12μm, and dried at 120°C to obtain a positive electrode sheet with a positive electrode material layer with a thickness of 100μm coated on one side. By repeating the above steps on the other surface of the aluminum foil, a positive electrode sheet with a positive electrode material layer coated on both sides was obtained. After drying under vacuum conditions at 120°C, through cold rolling, cutting, and slitting, a positive electrode sheet with a size of 74mm × 867mm was obtained. With respect to the total mass of the positive electrode material layer, the mass percentage W of manganese elementMn This is 5.85%, the mass percentage of iron element W Fe The figure was 30.59%. <Preparation of negative electrode piece>

[0076] Artificial graphite, the negative electrode active material, styrene-butadiene rubber, the binder, and acetylene black, the conductive agent, were mixed in a mass ratio of 97.4:1.4:1.2. Deionized water was added as the solvent to prepare a slurry with a solid content of 45 wt%, which was then uniformly stirred with a vacuum stirrer to obtain the negative electrode slurry. The negative electrode slurry was uniformly coated onto one surface of a 6 μm thick copper foil negative electrode current collector, dried at 120°C, and a negative electrode piece was obtained with the negative electrode material layer coated on one side. The coating weight of the negative electrode material layer was 142 mg / 1540 mm². 2 Subsequently, the above steps were repeated on the other surface of the copper foil to obtain a negative electrode piece with negative electrode material layers coated on both sides. After drying at 120°C, it was cold-rolled, then cut and tabs were welded to obtain a negative electrode piece with dimensions of 78 mm × 875 mm. The thickness of the negative electrode material layer on one side after cold rolling was 54.5 μm. <Preparation of Electrolyte>

[0077] In a glove box under an argon atmosphere with a water content of <10 ppm, ethylene carbonate (EC), propylene carbonate (PC), and diethyl carbonate (DEC) were mixed in a mass ratio of 1:1:1 to obtain a base solvent. The compound represented by formula I-1 and the lithium salt LiPF6 were added, dissolved, and homogeneously mixed to obtain an electrolyte. The mass percentage of the lithium salt LiPF6 relative to the total mass of the electrolyte was 12.5%, the mass percentage of the compound represented by formula I-1 was 0.05%, and the remainder was the base solvent. <Separator>

[0078] As a separator, a single-layer porous PE polymer film was used, with a thickness of 16 μm, a porosity of 39%, an inorganic coating layer of Al2O3, and organic particles of polyvinylidene fluoride. <Preparation of Lithium-ion Batteries>

[0079] The positive electrode piece, separator, and negative electrode piece prepared as described above were stacked in this order, with the separator positioned between the positive and negative electrode pieces to act as an separator. After that, they were wound together to obtain a bare battery. The bare battery was placed in an outer foil, the electrolyte prepared as described above was injected into the dried battery, and after processes such as vacuum sealing, standing, chemical formation, and shaping, the preparation of the lithium-ion battery was completed. In the chemical formation process, at 45±5℃, the battery was first charged with a constant current at a rate of 0.1C for 10 minutes, then charged with a constant current at a rate of 0.5C until a predetermined voltage Q=4.5V was reached, then charged with a constant voltage until the current was 0.05C or less, and then discharged with a constant current at a rate of 0.5C until 2.5V was reached. Examples 1-2 to 1-9

[0080] In the preparation of the positive electrode piece, the mass percentages of the first and second positive electrode materials were adjusted according to Table 1, and the mass percentages of conductive carbon black and the binder PVDF were not changed. In the preparation of the electrolyte, the mass percentage of additive A was adjusted according to Table 1, the mass percentage of the base solvent was changed accordingly, the mass ratio of each component in the base solvent was not changed, and the mass percentage of the lithium salt LiPF6 was not changed. Otherwise, the procedure was the same as in Example 1-1. Examples 2-1 to 2-26

[0081] In the preparation of the positive electrode piece, the mass percentage of the first positive electrode material, the type and mass percentage of the second positive electrode material were adjusted according to Table 2, and the mass percentages of conductive carbon black and the binder PVDF were not changed. In the preparation of the electrolyte, additive B was added, the type and mass percentage of additive A and the type and mass percentage of additive B were adjusted according to Table 2, the mass percentage of the base solvent was changed accordingly, the mass ratio of each component in the base solvent was not changed, and the mass percentage of the lithium salt LiPF6 was not changed. Otherwise, it was the same as in Example 1-1. Examples 3-1 to 3-16

[0082] In the preparation of the positive electrode piece, the type of the second positive electrode material was adjusted according to Table 3. In the preparation of the electrolyte, additive C was added, and the type and mass percentage of additive A, additive B, and additive C were adjusted according to Table 4. The mass percentage of the base solvent was changed accordingly, but the mass ratio of each component in the base solvent was not changed, and the mass percentage of the lithium salt LiPF6 was not changed. Otherwise, the procedure was the same as in Example 2-1. Comparative Example 1

[0083] In the preparation of the electrolyte, the procedure was the same as in Example 1-1, except that additive A was not added, the mass percentage of the base solvent was changed accordingly, the mass ratio of each component in the base solvent was not changed, and the mass percentage of the lithium salt LiPF6 was not changed. Comparative Example 2

[0084] In the preparation of the positive electrode piece, the mass percentages of the first and second positive electrode materials were adjusted according to Table 1, and the mass percentages of conductive carbon black and the binder PVDF were not changed. In the preparation of the electrolyte, the mass percentage of additive A was adjusted according to Table 1, the mass percentage of the base solvent was changed accordingly, the mass ratio of each component in the base solvent was not changed, and the mass percentage of the lithium salt LiPF6 was not changed. Otherwise, the procedure was the same as in Example 1-1. Comparative Example 3

[0085] In the preparation of the positive electrode pieces, the process was the same as in Example 1-1, except that the mass percentages of the first and second positive electrode materials were adjusted according to Table 1, and the mass percentages of conductive carbon black and PVDF (a binder) were not changed. Comparative Example 4

[0086] In the preparation of the positive electrode piece, the procedure was the same as in Example 1-1, except that the second positive electrode material was not added, only the first positive electrode material was added, and the mass percentages of conductive carbon black and PVDF (a binder) were not changed. The preparation parameters and performance parameters for each example and comparative example are shown in Tables 1 to 3.

[0087] [Table 1]

[0088] [Table 2]

[0089] [Table 3]

[0090] As can be seen from Examples 1-1 to 1-9 and Comparative Examples 1 to 3, the electrolyte containing additive A and the positive electrode piece of the second positive electrode material were combined and applied to a lithium-ion battery, with the mass percentage a of additive A and 100 a / W. Mn When the value is within the range of the present invention, the lithium-ion battery has a relatively low resistance at 50% charge, a relatively high cycle capacity retention rate, a relatively low thickness expansion rate at 60°C storage, and a good rate discharge capacity retention rate. This indicates that the cycle performance and high-temperature storage performance of the lithium-ion battery have improved. Mass percentage and / or 100 a / W of additive A in Comparative Examples 1 to 3 Mn Because the value is outside the scope of the present invention, the resulting lithium-ion battery has a relatively high resistance at 50% charge, a relatively low cycle capacity retention rate, and a relatively high thickness expansion rate when stored at 60°C. This indicates that the lithium-ion battery has relatively poor cycle performance and high-temperature storage performance. In Comparative Example 4, the positive electrode material layer does not contain manganese, and the resulting lithium-ion battery has a relatively high resistance at 50% charge and a relatively low cycle capacity retention rate. This indicates that the lithium-ion battery has relatively low cycle performance.

[0091] The mass percentage b of additive B typically affects the cycle performance and high-temperature storage performance of lithium-ion batteries. As can be seen from Examples 2-1 to 2-7, when the mass percentage b of additive B is within the range of the present invention, the lithium-ion battery has lower resistance at 50% charge, a higher cycle capacity retention rate, a lower thickness expansion rate at 60°C storage, and a good rate discharge capacity retention rate. This indicates that the cycle performance and high-temperature storage performance of the lithium-ion battery have improved.

[0092] Mass percentage W of the element iron Fe , the mass percentage of manganese element W Mn , 100b / (W Fe +W Mn ) and a / b typically affect the cycle performance and high-temperature storage performance of lithium-ion batteries. As can be seen from Examples 2-8 to 2-15, the mass percentage of iron W Fe , the mass percentage of manganese element W Mn , 100b / (W Fe +W Mn If (a) and (b) are within the scope of the present invention, the lithium-ion battery has a relatively low resistance at 50% charge, a relatively high cycle capacity retention rate, a reduced thickness expansion rate at 60°C storage, and a good rate discharge capacity retention rate. This indicates that the cycle performance and high-temperature storage performance of the lithium-ion battery have improved.

[0093] The type of additive A typically affects the cycle performance and high-temperature storage performance of lithium-ion batteries. As can be seen from Examples 2-1 and 2-16 to 2-18, when the type of additive A is within the scope of the present invention, the lithium-ion battery exhibits relatively low resistance at 50% charge and relatively low thickness expansion rate at 60°C storage, and a relatively high cycle capacity retention rate. As a result, the lithium-ion battery in the present invention has good cycle performance and high-temperature storage performance.

[0094] The type of additive B typically affects the cycle performance and high-temperature storage performance of lithium-ion batteries. As can be seen from Examples 2-1 and 2-19 to 2-21, when the type of additive B is within the scope of the present invention, the lithium-ion battery exhibits relatively low resistance at 50% charge and relatively low thickness expansion rate at 60°C storage, and a relatively high cycle capacity retention rate. As a result, the lithium-ion battery in the present invention has good cycle performance and high-temperature storage performance.

[0095] The a / b value typically affects the cycle performance and high-temperature storage performance of lithium-ion batteries. As can be seen from Examples 2-10 to 2-15 and Example 2-22, when the additive a / b value is within the range of the present invention, the lithium-ion battery exhibits relatively low resistance at 50% charge and thickness expansion rate at 60°C storage, and a relatively high cycle capacity retention rate. In Example 2-22, since the a / b value is outside the range of the present invention, the lithium-ion battery exhibits relatively high resistance at 50% charge and thickness expansion rate at 60°C storage, and a relatively low cycle capacity retention rate, thus the lithium-ion battery in the present invention has good cycle performance and high-temperature storage performance.

[0096] The type of second cathode material typically affects the cycle performance and high-temperature storage performance of lithium-ion batteries. As can be seen from Examples 2-1 and 2-23 to 2-26, when the type of second cathode material is within the scope of the present invention, and the cathode material layer has a first diffraction peak and a second diffraction peak in the XRD diffraction pattern (Cu target, Kα line) at 3.6V, the lithium-ion battery exhibits relatively low resistance at 50% charge and thickness expansion rate at 60°C storage, and a relatively high cycle capacity retention rate.

[0097] The type of additive C typically affects the cycle performance, high-temperature storage performance, and rate performance of a lithium-ion battery. As can be seen from Examples 3-1 to 3-13, when an electrolyte containing additive C is applied to a lithium-ion battery, and the mass percentage c of additive C is within the range of the present invention, the lithium-ion battery exhibits further reduced resistance at 50% charge, further improved cycle capacity retention, relatively low thickness expansion rate at 60°C storage, and further improved rate performance. Thus, the lithium-ion battery in the present invention has good cycle performance, high-temperature storage performance, and rate performance.

[0098] Different types of electrolytes and second cathode materials typically affect the cycle performance and high-temperature storage performance of lithium-ion batteries. As can be seen from Examples 3-14 to 3-16, when a combination of electrolytes and second cathode materials within the scope of the present invention is used, lithium-ion batteries exhibit further improved cycle capacity retention and further reduced resistance at 50% charge and thickness expansion rate at 60°C storage. This demonstrates that lithium-ion batteries have good cycle performance, high-temperature storage performance, and rate performance.

[0099] The terms “include,” “equip,” or any other variations thereof are intended to cover non-exclusive inclusion. Thus, a process, method, or article that includes a set of elements includes not only those elements but also any other unspecified elements or elements specific to that process, method, or article.

[0100] Each embodiment in this specification will be described using the relevant method, and any identical or similar parts between embodiments may be referenced to one another. Each embodiment will focus on describing the differences from other embodiments.

[0101] The above are merely preferred embodiments of the present invention and are not intended to limit it. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention are all within the scope of protection of the present invention.

Claims

1. An electrochemical apparatus comprising a positive electrode piece, a negative electrode piece, and an electrolyte, The electrolyte contains additive A, The additive A comprises at least one of the compounds represented by formula I and the compound represented by formula II. With respect to the total mass of the electrolyte, the mass percentage a of additive A is 0.05% to 4.0%. 【Chemistry 1】 Here, R １ ~R ９ These are, independently, a hydrogen atom, a fluorine atom, and an unsubstituted or fluorine-substituted C atom. １ ~C ５ alkyl groups, unsubstituted or fluorine-substituted C ２ ~C ５ The alkenyl group, or unsubstituted or fluorine-substituted C ２ ~C ５ Selected from the alkynyl groups, The positive electrode piece includes a positive electrode material layer, The positive electrode material layer contains manganese and iron elements. When the mass percentage of the manganese element is W with respect to the total mass of the positive electrode material layer Ｍｎ in this case W Ｍｎ And a is 0.43 ≤ 100a / W Ｍｎ An electrochemical apparatus that satisfies ≤ 170.

94.

2. W Ｍｎ And a is 0.86 ≤ 100 a / W Ｍｎ The electrochemical apparatus according to claim 1, satisfying ≤ 34.

21.

3. The electrolyte contains additive B, The additive B comprises at least one of the compounds represented by formula III, formula IV, formula V, and formula VI. With respect to the total mass of the electrolyte, the mass percentage b of additive B is 0.05% to 4.0%. 【Chemistry 2】 Here, R １１ , R １２ , R １６ , R １９ These are, independently, a hydrogen atom, a fluorine atom, and an unsubstituted or fluorine-substituted C atom. １ ~C ５ alkyl groups, unsubstituted or fluorine-substituted C ２ ~C ５ The alkenyl group, or unsubstituted or fluorine-substituted C ２ ~C ５ Selected from the alkynyl groups, R １０ , R １５ , R １８ Each of these is independently selected from an oxygen atom, a methylene group, an ethylene group, a methyleneoxy group, or an ethyleneoxy group. R １３ , R １４ These are, independently, unsubstituted or fluorine-substituted C １ ~C ５ Selected from the alkylene groups, R １７ , R ２０ These are, independently, unsubstituted or fluorine-substituted C １ ~C ８ Alkylene group, unsubstituted or fluorine-substituted C ２ ~C ８ The alkenylene group, or unsubstituted or fluorine-substituted C ２ ~C ８ The electrochemical apparatus according to claim 1, selected from the alkynylene groups.

4. W is the mass percentage of the iron element relative to the total mass of the positive electrode material layer. Ｆｅ In that case, W Ｍｎ , W Ｆｅ And b is 0.13 ≤ 100b / (W Ｆｅ +W Ｍｎ The electrochemical apparatus according to claim 3, satisfying ) ≤ 11.

41.

5. W Ｍｎ , W Ｆｅ And b is 0.14 ≤ 100b / (W Ｆｅ +W Ｍｎ The electrochemical apparatus according to claim 4, satisfying ) ≤ 5.

49.

6. The electrochemical apparatus according to claim 1, wherein the compound represented by formula I or the compound represented by formula II includes at least one of the compounds represented by the following formulas I-1 to II-7. 【Transformation 3】

7. The electrochemical apparatus according to claim 3, wherein the compound represented by formula III, the compound represented by formula IV, the compound represented by formula V, or the compound represented by formula VI includes at least one of the following compounds represented by formulas III-1 to VI-7. 【Chemistry 4】 【Transformation 5】 【Transformation 6】

8. The electrochemical apparatus according to claim 3, wherein the ratio a / b of the mass percentages of additive A to additive B satisfies 0.1 ≤ a / b ≤ 10.

9. The positive electrode material layer includes a first positive electrode material and a second positive electrode material. The first cathode material is LiFePO ４ And, The second cathode material is a lithium manganese composite oxide, The chemical formula of the lithium manganese composite oxide is Li １＋ｒ Mn １－ｐ T ｐ O ２－ｓ M ｓ In the formula, -0.1 < r < 0.2, 0 ≤ p < 0.2, 0 ≤ s < 0.2, T contains at least one of Co, Ni, Ti, Zn, Mg, Al, V, Cr, and Zr, and M contains at least one of S, N, F, Cl, and Br. The electrochemical apparatus according to claim 4.

10. The mass percentage W of the manganese element relative to the total mass of the positive electrode material layer Ｍｎ The amount is 2.34% to 11.69%, and the mass percentage W of the iron element. Ｆｅ The percentages ranged from 27.05% to 32.71%. The ratio W of the mass percentages of the manganese element and the iron element. Ｍｎ / W Ｆｅ The range is 0.072 to 0.

432. The electrochemical apparatus according to claim 4.

11. The electrochemical apparatus according to claim 1, wherein the positive electrode material layer has a first diffraction peak in the range of 18° to 19° and a second diffraction peak in the range of 15° to 16° in the XRD diffraction pattern at 3.6 V.

12. The electrolyte contains additive C, The additive C comprises at least one of lithium difluorophosphate, lithium difluoro(oxalato)borate, lithium tetrafluoroborate, and lithium bis(oxalato)borate. The electrochemical apparatus according to claim 1, wherein the mass percentage c of the additive C is 0.01% to 2% of the mass of the electrolyte.

13. An electronic apparatus comprising an electrochemical apparatus as described in any one of claims 1 to 12.

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