Electrochemical apparatus and electronic apparatus

Abstract

The present invention relates to an electrochemical device and an electronic device. The electrochemical device includes a positive electrode, a negative electrode, and an electrolytic solution. The positive electrode includes a positive electrode active material layer, the positive electrode active material layer includes a positive electrode active material, and the positive electrode active material includes a first positive electrode active material and a second positive electrode active material. After the electrochemical device is fully discharged, the Raman spectrum of the positive electrode active material layer has a first characteristic peak at a wavelength of 398 cm -1 ~408 cm -1 and a second characteristic peak at a wavelength of 940 cm -1 ~960 cm -1 . The second positive electrode active material contains aluminum element. The electrochemical device simultaneously has both a high energy density and good high-temperature cycle characteristics.

Description

[Technical Field]

[0001] This invention belongs to the field of electrochemical technology, and more specifically relates to electrochemical apparatus and electronic apparatus. [Background technology]

[0002] In recent years, electrochemical devices, such as lithium-ion batteries, have rapidly developed in the fields of portable consumer electronics, new energy vehicles, and large-scale energy storage due to their advantages such as high operating voltage, environmental friendliness, small size, light weight, and long cycle life. Lithium iron phosphate is widely used as a cathode material in electrochemical devices such as lithium-ion batteries due to its excellent cycle characteristics and safety performance. As the adoption rate of new energy vehicles accelerates, the demand for longer driving ranges is further increasing the requirements for battery energy density, cycle characteristics, and other factors. [Overview of the project]

[0003] The present invention aims to provide electrochemical and electronic devices that improve the energy density of electrochemical devices and enhance their high-temperature cycling characteristics.

[0004] A first aspect of the present invention provides an electrochemical apparatus comprising a positive electrode, a negative electrode, and an electrolyte, wherein the positive electrode comprises a positive electrode active material layer, the positive electrode active material layer comprises a positive electrode active material, the positive electrode active material comprises a first positive electrode active material and a second positive electrode active material, and after the electrochemical apparatus is completely discharged, the Raman spectrum of the positive electrode active material layer is wavenumber 398cm -1 ~408cm -1 It has a first characteristic peak, wavenumber 940cm -1 ~960cm -1It has a second characteristic peak, and the second positive electrode active material contains an aluminum element. The first characteristic peak is the characteristic peak of the second positive electrode active material, the second characteristic peak is the characteristic peak of the first positive electrode active material, the second positive electrode active material has a higher capacity per gram, and the aluminum element can enhance the stability of the manganese-oxygen bond in the second positive electrode active material during the cycling process, endow the positive electrode active material layer with relatively excellent structural stability, increase the energy density of the electrochemical device, and improve its high-temperature cycling characteristics.

[0005] In an embodiment of the present invention some after the electrochemical device is fully discharged, the Raman spectrum of the positive electrode active material layer is wavenumber 591 cm -1 ~611 cm -1 has a third characteristic peak, and the full width at half maximum of the third characteristic peak is 15 cm -1 ~60 cm -1 and the third characteristic peak is the characteristic peak of the second positive electrode active material. When the full width at half maximum of the third characteristic peak is within the above range, it is shown that the interior of the second positive electrode active material has a stable crystal structure, can suppress the phase transition of the material structure during the cycling process, improve the structural stability of the material, and improve the cycling characteristics of the electrochemical device.

[0006] In an embodiment of the present invention some the full width at half maximum of the first characteristic peak is 15 cm -1 ~60 cm -1 and the full width at half maximum of the second characteristic peak is 5 cm -1 ~25 cm -1 and the full width at half maximum of the first characteristic peak is larger than that of the second characteristic peak. Since the crystallinity of the second positive electrode active material is lower than that of the first positive electrode active material, its full width at half maximum is relatively large, the full width at half maximum of the first positive electrode active material is relatively small, the crystallinity is good, and the structural change during the charge-discharge process is small. The active ions inside the second positive electrode active material compensate for the loss of active ions on the surface of the negative electrode active material, ensure the transport of active ions, and are beneficial to the improvement of the cycling characteristics of the electrochemical device.

[0007] In an embodiment of the present invention someIn this embodiment, the first positive electrode active material contains iron, and the second positive electrode active material contains manganese. The second positive electrode active material has a higher capacity per gram, which allows the electrochemical apparatus to have a higher discharge ratio capacity. A synergistic effect occurs between the first and second positive electrode active materials, and during the charge-discharge process of the electrochemical apparatus, active ions in the second positive electrode active material are released, effectively compensating for the irreversible loss of active ions on the surface of the negative electrode active material. The remaining active ions can be inserted into the first positive electrode active material, effectively increasing the capacity of the positive electrode active material and improving the cycle characteristics of the electrochemical apparatus.

[0008] This invention some In this embodiment, the positive electrode active material layer contains manganese and aluminum element mass fraction ω Al This is 0.1%≦ω with respect to the mass of manganese element in the positive electrode active material layer. Al The condition ≤5% is satisfied. When the mass fraction of aluminum satisfies the above relationship, the stability of the manganese-oxygen bond in the second positive electrode active material can be enhanced, and the cycle characteristics of the electrochemical apparatus can be further improved.

[0009] This invention some In the embodiment, the mass fraction of manganese element ω Mn and the mass fraction of iron element ω Fe This is 0.01% ≤ ω with respect to the mass of the positive electrode active material layer. Mn / ω Fe ≤30%, preferably 1% ≤ω Mn / ω Fe The condition ≤25% is met. When the mass fractions of manganese and iron are within the above range, the energy density of the electrochemical apparatus can be further increased, and its cycle characteristics can be improved.

[0010] This invention someIn this embodiment, the positive electrode active material layer contains element M, which is at least one selected from the group consisting of Nb, Mg, Ti, W, Ga, Zr, Y, V, Sr, Mo, Cr, Sn, La, and Ce. Adding element M to the second positive electrode active material can increase the stability of the manganese-oxygen bond inside the material, suppress the elution of manganese, further improve the cycle characteristics of the electrochemical apparatus, and increase its energy density.

[0011] This invention some In this embodiment, the mass fraction ω of element M M This is 0.03% < ω with respect to the mass of the positive electrode active material layer. M The value ≤2.5% is satisfied. When the mass fraction of element M is within this range, the cycle characteristics of the electrochemical apparatus can be more effectively improved, and its energy density can be increased.

[0012] This invention some In this embodiment, the electrolyte includes an additive, the additive including a fluorocarbonate and / or an inorganic lithium salt. The fluorocarbonate and / or inorganic lithium salt helps to form a dense and stable interfacial film on the surface of the positive electrode active material, further enhancing protection for the positive electrode active material and improving the cycle characteristics of the electrochemical apparatus.

[0013] This invention some In this embodiment, the mass fraction of the additive is 0.01% to 10% of the mass of the electrolyte. When the mass fraction of the additive in the electrolyte is within an appropriate range, it helps to form an interfacial film of appropriate thickness on the surface of the positive electrode active material, while simultaneously having low impedance and further improving the cycle characteristics of the electrochemical apparatus.

[0014] This invention some In the embodiment, the fluorocarbonate comprises at least one of fluoroethylene carbonate and fluoropropylene carbonate.

[0015] This invention someIn this embodiment, the inorganic lithium salt comprises at least one of lithium difluorophosphate and lithium tetrafluoroborate.

[0016] This invention some In this embodiment, the mass fraction of fluorocarbonate is 0.01% to 8% of the mass of the electrolyte.

[0017] This invention some In this embodiment, the mass fraction of fluorocarbonate is 0.01% to 5% of the mass of the electrolyte.

[0018] This invention some In this embodiment, the mass fraction of the inorganic lithium salt is 0.01% to 3% of the mass of the electrolyte.

[0019] This invention some In this embodiment, the mass fraction of the inorganic lithium salt is 0.01% to 1.5% of the mass of the electrolyte.

[0020] A second aspect of the present invention provides an electronic apparatus including the electrochemical apparatus of the first aspect of the present invention. [Brief explanation of the drawing]

[0021] [Figure 1] Figure 1 is the Raman spectrum diagram of the positive electrode active material layer of Example 1. [Modes for carrying out the invention]

[0022] To further clarify the object, technical proposal, and advantages of the present invention, the technical proposal of the present invention will be described clearly and completely below in conjunction with the examples. Obviously, the examples described are some examples of the present invention, but not all examples. The related examples described herein are illustrative and are used to provide a basic understanding of the present invention. The examples of the present invention should not be construed as limiting the present invention. All other examples obtained by a person skilled in the art without creative effort based on the technical proposal and examples provided herein are within the scope of the protection of the present invention.

[0023] For the sake of brevity, this specification specifically discloses only a few numerical ranges. However, any lower limit may be combined with any upper limit to form an unspecified range, and any lower limit may be combined with any other lower limit to form an unspecified range, and similarly, any upper limit may be combined with any other upper limit to form an unspecified range. Furthermore, each individually disclosed point or single numerical value itself may be combined with any other point or single numerical value, or with any other lower limit or upper limit, to form an unspecified range, as a lower or upper limit.

[0024] In this specification, unless otherwise specified, "above" and "below" include the respective numerical values.

[0025] Unless otherwise specified, the terms used herein have the meanings generally understood by those skilled in the art. Unless otherwise specified, the numerical values ​​of each parameter described in this invention can be measured by various measurement methods commonly used in the art (for example, by the methods shown in the examples of this invention).

[0026] A list of items connected by the terms “at least one of,” “at least one of,” “at least one kind of,” or other similar terms means any combination of the listed items. For example, if items A and B are listed, the phrase “at least one of A and B” means A only, B only, or A and B. In other examples, if items A, B, and C are listed, the phrase “at least one of A, B, and C” means A only, or B only, C only, A and B (excluding C), A and C (excluding B), B and C (excluding A), or all of A, B, and C. Item A may contain a single element or multiple elements. Item B may contain a single element or multiple elements. Item C may contain a single element or multiple elements.

[0027] Electrochemical apparatus A first embodiment of the present invention provides an electrochemical apparatus, which includes any apparatus that causes an electrochemical reaction to convert chemical energy and electrical energy into each other. Specific examples include, but are not limited to, a lithium-ion battery.

[0028] The electrochemical apparatus of the present invention comprises a positive electrode, a negative electrode, and an electrolyte. The positive electrode comprises a positive electrode active material layer, the positive electrode active material layer comprises a positive electrode active material, and the positive electrode active material comprises a first positive electrode active material and a second positive electrode active material. After the electrochemical apparatus is completely discharged, the Raman spectrum of the positive electrode active material layer is obtained. wavenumber 398cm -1 ~408cm -1 It has a first characteristic peak, wavenumber 940cm -1 ~960cm -1 The second characteristic peak is present, and the second positive electrode active material contains aluminum. The Raman spectrum of the positive electrode active material layer is wavenumber 398cm -1 ~408cm -1 It has a first characteristic peak, wavenumber 940cm -1 ~960cm -1The material has a second characteristic peak, where the first characteristic peak corresponds to the second cathode active material, and the second characteristic peak corresponds to the first cathode active material. Since the second cathode active material has a relatively high volume per gram, the cathode active material containing both the second and first cathode active materials also has a relatively high volume per gram, which is advantageous for further improving the energy density of the electrochemical apparatus. The second cathode active material contains aluminum, which improves the variation in the bond length of the manganese-oxygen bond in the second cathode active material during the cycle process, strengthens the stability of the manganese-oxygen bond, and further improves the cycle characteristics of the electrochemical apparatus. At the same time, the synergistic effect of the first and second cathode active materials gives the cathode active material layer relatively excellent structural stability, enabling the electrochemical apparatus to have high energy density and high-temperature cycle characteristics.

[0029] In some embodiments of the present invention, wavenumber 398cm -1 ~408cm -1 The first characteristic peak is a characteristic peak due to the stretching vibration of the Mn-O bond in the second positive electrode active material. wavenumber 940cm -1 ~960cm -1 The second characteristic peak is (PO4) in the first cathode active material. 3- This is a characteristic peak of the internal mode.

[0030] In the present invention, a fully discharged electrochemical device refers to an electrochemical device that has been charged to 3.65V with a constant current of 0.2C, then charged to 0.05C with a constant voltage, left standing for 5 minutes, then discharged to 2.5V with a constant current of 0.2C, and after two cycles following the above charge-discharge process, the resulting electrochemical device is in a fully discharged state.

[0031] In some embodiments of the present invention, the full width at half maximum of the first characteristic peak is 15 cm. -1 ~60cm -1 This may also be the case, and the full width at half maximum of the second feature peak is 5 cm. -1 ~25cm -1It is also possible that the full width at half maximum (FWHM) of the first feature peak is greater than the FWHM of the second feature peak. For example, the FWHM of the first feature peak may be 15 cm. -1 , 25cm -1 , 38cm -1 , 45cm -1 , 52cm -1 , or 60cm -1 It may be or may be within the range of any of the above values. The half-width of the second feature peak is 5 cm. -1 , 8cm -1 , 12cm -1 , 16cm -1 , 22cm -1 , or 25cm -1 The second positive electrode active material has lower crystallinity than the first positive electrode active material, resulting in a relatively large full width at half maximum (FWHM). The first positive electrode active material has a relatively small FWHM and good crystallinity, resulting in minimal structural changes during the charge-discharge process. The active ions inside the second positive electrode active material compensate for the loss of active ions on the surface of the negative electrode active material, and sufficient active ions can be reinserted into the second positive electrode active material, ensuring the transport of active ions and contributing to improved cycle characteristics of the electrochemical apparatus.

[0032] In some embodiments of the present invention, after the electrochemical apparatus has been completely discharged, the Raman spectrum of the positive electrode active material layer is wavenumber 591cm -1 ~611cm -1 It has a third characteristic peak, and the full width at half maximum of the third characteristic peak is 15 cm. -1 ~60cm -1 This is also acceptable. For example, the full width at half maximum of the third feature peak is 15 cm. -1 , 25cm -1 , 40cm -1 , 45cm -1 54cm -1 , or 60cm -1It may be, or within the range of any of the above values. It has been shown that when the full width at half maximum of the third characteristic peak is within the above range, the interior of the second cathode active material has a stable crystal structure, which suppresses phase transitions of the material structure during the cycle process, enhances the structural stability of the material, and improves the cycle characteristics of the electrochemical apparatus.

[0033] In the electrochemical apparatus of the present invention, the third characteristic peak corresponds to the characteristic peak of the second positive electrode active material. As can be seen from Figure 1, the Raman spectrum of the positive electrode active material layer of Example 1 provided in the present invention includes the first characteristic peak, the second characteristic peak, and the third characteristic peak.

[0034] In this invention, the Raman spectrum of the positive electrode active material layer, as well as the full width at half maximum of the first, second, and third characteristic peaks, have meanings known in the art and can be measured using methods known in the art. For example, a lithium-ion battery is charged to 3.65V with a constant current of 0.2C, then charged to 0.05C with a constant voltage, left to stand for 5 minutes, then discharged to 2.5V with a constant current of 0.2C, and this cycle is repeated twice. After completion, the lithium-ion battery is disassembled, the positive electrode piece is removed, the positive electrode piece is immersed in DMC (dimethyl carbonate) for 30 minutes to remove the electrolyte and by-products from the surface of the positive electrode piece, and then dried in a ventilated hood for 4 hours. The dried positive electrode piece is sliced ​​using an ion milling apparatus (JEOL-IB-09010CP), and measured using a Raman spectrometer (model HR Evolution) in the wavenumber range of 150~1200cm². -1 Next, a 2cm*2cm area is selected, the mean value of the spectrum is taken, and a Raman spectrum diagram is obtained. The full width at half maximum refers to the total width of the band when the height of the characteristic peak is half of its maximum height, that is, the width of the peak when it is half of its peak height.

[0035] In some embodiments, the first positive electrode active material contains iron, and the second positive electrode active material contains manganese. The first positive electrode active material contains an olivine structure, which is relatively stable, and during the charge-discharge process of the electrochemical apparatus, the volume change is small, meaning that the insertion and removal of active ions have little effect on the structure of the first positive electrode active material, resulting in good charge-discharge reversibility. The second positive electrode active material has a relatively high capacity per gram, which allows the electrochemical apparatus to have a relatively high discharge ratio capacity. The electrochemical apparatus of the present invention can fully exhibit the synergistic effect between the first positive electrode active material and the second positive electrode active material. During the charge-discharge process of the electrochemical apparatus, active ions in the second positive electrode active material are removed, some of which accumulate on the negative electrode, effectively compensating for the irreversible loss of active ions on the surface of the negative electrode active material due to SEI film repair, while the remaining active ions can be inserted into the first positive electrode active material, improving the cycle characteristics of the electrochemical apparatus.

[0036] In some embodiments, the first positive electrode active material includes, but is not limited to, lithium iron phosphate or a composite material of lithium iron phosphate and carbon.

[0037] In some embodiments, the positive electrode active material layer contains manganese and aluminum mass fraction ω Al This is 0.1%≦ω with respect to the mass of manganese element in the positive electrode active material layer. Al The value ≤5% is satisfied. For example, the mass fraction ω of the element aluminum. Al This is 0.15% ≤ ω with respect to the mass of manganese element in the positive electrode active material layer. Al ≤5%, 0.8%≦ω Al ≤5%, 1.2%≦ω Al ≤5%, 2.6%≦ω Al ≤5%, 3.5%≦ω Al ≤5%, 4%≤ω Al ≤5%, 0.2%≦ω Al ≤4%, 0.9%≦ω Al ≤4%, 1.5%≦ω Al ≤4%, 2.5%≦ω Al ≤4%, 3%≤ω Al ≤4%, 0.3%≦ωAl ≤3%, 1% ≤ ω Al ≤3%, 1.6% ≤ ω Al ≤3%, 0.8% ≤ ω Al ≤2%, or 0.1% ≤ ω Al satisfies ≤1%. Preferably, the mass fraction ω of the aluminum element Al satisfies 0.3% ≤ ω with respect to the mass of the manganese element in the positive electrode active material layer Al ≤3%. The aluminum element is closely related to the peak position of the first characteristic peak of the second positive electrode active material. When the mass fraction of the aluminum element satisfies the above relational expression, the peak position of the first characteristic peak shifts to the right, strengthening the stability of the manganese-oxygen bond in the second positive electrode active material, and further improving the high-temperature cycle characteristics of the electrochemical device. If the doping amount of the aluminum element in the second positive electrode active material is too large, the aluminum element occupies the active positions of the active ions, resulting in a decrease in the capacity per gram of the second positive electrode active material, which is disadvantageous for improving the energy density of the electrochemical device.

[0038] In some embodiments, the mass fraction ω of the manganese element Mn and the mass fraction ω of the iron element Fe satisfies 0.01% ≤ ω with respect to the mass of the positive electrode active material layer Mn / ω Fe ≤30%. The mass fraction ω of the manganese element Mn and the mass fraction ω of the iron element Fe can reflect the mass fractions of the second positive electrode active material and the first positive electrode active material in the positive electrode active material. The mass fraction ω of the manganese element MnThe higher it is, the higher the mass fraction of the second positive electrode active material in the positive electrode active material indicates. Since the second positive electrode active material has a high capacity per gram, at this time, the electrochemical device has a high discharge specific capacity. The active ions of the second positive electrode active material can desorb from it during the cycle process of the electrochemical device and deposit on the negative electrode, compensating for the loss of active ions on the surface of the negative electrode active material. When the mass fraction of the second positive electrode active material in the positive electrode active material is high, more desorbable active ions can be provided, which can not only effectively compensate for the loss of active ions on the surface of the negative electrode active material, but also reinsert sufficient active ions into the second positive electrode active material, ensure the transport of active ions, effectively increase the cycle capacity retention rate of the electrochemical device, increase its energy density, and improve its cycle characteristics. Compared with the first positive electrode active material, the mass fraction of the second positive electrode active material should not be too high. If the mass fraction of the second positive electrode active material is too high, there will be too many desorbable and compensable active ions it can provide, and if the amount is more than the amount of active ions that can be reinserted into the positive electrode active material layer, the internal resistance will increase and the discharge specific capacity of the electrochemical device will decrease. Therefore, the mass fractions of the second positive electrode active material and the first positive electrode active material in the positive electrode active material, that is, the mass fraction ω Mn of manganese element and the mass fraction ω Fe of iron element

[0039] In some embodiments, the mass fraction ω Mn of manganese element and the mass fraction ω Fe of iron element Mn are such that 0.05% ≤ ω Fe / ω Mn ≤ 30%, 0.1% ≤ ω Fe / ω Mn ≤ 30%, 0.5% ≤ ω Fe / ω Mn ≤ 30%, 1% ≤ ω Fe / ω Mn ≤ 30%, 5% ≤ ω Fe / ω<000′′0105>≤ 30%, 10% ≤ ω Fe / ω Mn ≤ 30%, 15% ≤ ω Fe / ω Mn ≤ 30%, 20% ≤ ω Fe / ω Mn ≤ 30%, 25% ≤ ω Fe / ω Mn ≤ 30%, 30% ≤ ω Fe / ω Mn ≤ 30%. By controlling them within the above ranges, the cycle characteristics of the electrochemical device can be effectively improved and its energy density can be increased.

[0039] Mn / h Fe ≦30%,25%≦ω Mn / h Fe ≦30%、0.05%≦ω Mn / h Fe ≦25%、0.1%≦ω Mn / h Fe ≦25%、0.5%≦ω Mn / h Fe ≦25%、1%≦ω Mn / h Fe ≦25%、5%≦ω Mn / h Fe ≦25%、10%≦ω Mn / h Fe ≦25%、15%≦ω Mn / h Fe ≦25%、20%≦ω Mn / h Fe ≦25%、0.05%≦ω Mn / h Fe ≦20%、0.1%≦ω Mn / h Fe ≦20%、0.5%≦ω Mn / h Fe ≦20%、1%≦ω Mn / h Fe ≦20%、5%≦ω Mn / h Fe ≦20%、10%≦ω Mn / h Fe ≦20%、15%≦ω Mn / h Fe ≦20%、0.05%≦ω Mn / h Fe ≦15%、0.1%≦ω Mn / h Fe ≦15%、0.5%≦ω Mn / h Fe ≦15%、1%≦ω Mn / h Fe ≦15%、5%≦ω Mn / h Fe ≦15%、10%≦ω Mn / h Fe ≦15%、0.05%≦ω Mn / h Fe ≦10%、0.1%≦ω Mn / h Fe ≦10%、0.5%≦ω Mn / h Fe ≦10%、1%≦ωMn / ω Fe ≤10%, 5%≤ω Mn / ω Fe ≤10%, 0.05%≦ω Mn / ω Fe ≤5%, 0.1%≦ω Mn / ω Fe ≤5%, 0.5%≦ω Mn / ω Fe ≤5%, 1%≤ω Mn / ω Fe ≤5%, 0.05%≦ω Mn / ω Fe ≤1%, 0.1%≦ω Mn / ω Fe ≤1%, or 0.05% ≤ ω Mn / ω Fe Satisfies ≤0.1%. Preferably, the mass fraction of manganese element ω Mn and the mass fraction of iron element ω Fe is 1%≦ω Mn / ω Fe The condition ≤25% is met, and in this case, the electrochemical apparatus has superior cycle characteristics and a higher energy density.

[0040] In some embodiments, the positive electrode active material layer contains element M, where element M is Nb, Mg, Ti, W, Ga, Zr 、Y , is at least one selected from the group consisting of V, Sr, Mo, Cr, Sn, La, and Ce. For example, element M may be Nb, Ga, Mo, V, W and Y, or La and Ce. Element M may be one or more of the above elements. Adding element M to the second positive electrode active material can increase the stability of the manganese-oxygen bond inside the material, suppress the elution of manganese, and further improve the high-temperature cycle characteristics of the electrochemical apparatus. At the same time, element M can increase the content of desorbable active ions in the second positive electrode active material, allowing sufficient active ions to be desorbed from the second positive electrode active material to compensate for the loss of active ions on the surface of the negative electrode active material, and allowing sufficient active ions to be reinserted into the positive electrode active material layer, further increasing the capacity and energy density of the electrochemical apparatus.

[0041] In some embodiments, the mass fraction ω of element M M This is 0.03% < ω with respect to the mass of the positive electrode active material layer. M The value ≤2.5% is satisfied. For example, the mass fraction ω of element M. M is 0.05%≦ω M ≤1.5%, 0.1%≦ω M ≤1.5%, 0.5%≦ω M ≤1.5%, 1% ≤ ω M ≤1.5%, 0.05% ≤ ω M ≤1%, 0.1% ≤ ω M ≤1% or 0.5% ≤ ω M The mass fraction ω of element M satisfies ≤1%. M 0.03%<ω M Satisfying ≤2.5% is advantageous for further improving the stability of the manganese-oxygen bond and suppressing manganese elution, as well as for setting the content of desorbable lithium in the second positive electrode active material to an appropriate range. This allows the second positive electrode active material to contain enough active ions to compensate for the loss of active ions on the surface of the negative electrode active material, as well as enough active ions to be reinserted into the positive electrode active material layer, thereby further increasing the energy density of the electrochemical apparatus and improving the high-temperature cycle characteristics of the electrochemical apparatus. In some embodiments, the mass fraction ω of element M M This is 0.03% < ω with respect to the mass of the positive electrode active material layer. M The ≤1.5% requirement is met, which is advantageous for improving the energy density of electrochemical devices and the high-temperature cycle characteristics of electrochemical devices.

[0042] In this invention, the types of elements in the positive electrode active material layer can be measured using methods known in the art. For example, a positive electrode piece obtained by disassembling a lithium-ion battery is dried, the dried positive electrode piece is sliced ​​using an ion milling apparatus (JEOL-IB-09010CP), the cross-section of the slice is observed using a scanning electron microscope (SEM), particles in the cross-section are searched for, and the types of elements in the positive electrode active material layer are determined after measurement using an energy-dispersive spectrometer (EDS).

[0043] In the present invention, the content of each element in the positive electrode active material layer can be measured using methods known in the art. For example, a positive electrode piece obtained by disassembling a lithium-ion battery is washed with DMC, the active material layer of the positive electrode piece washed with DMC is scraped off with a doctor blade, and it is dissolved in a mixed solvent (for example, 0.4 g of positive electrode active material layer is mixed with 10 mL of aqua regia (a 1:1 mixture of nitric acid and hydrochloric acid) and 2 mL of HF), the volume is adjusted to 100 mL, and then the mass fraction of elements such as Mn, Fe, Al, and M in the solution is measured using an ICP (Inductively coupled plasma) analyzer.

[0044] In some embodiments, for example, the second positive electrode active material can be prepared using the following method: MnOOH is placed in a corundum crucible and heated to 500°C at a heating rate of 5°C / min under an air atmosphere, and the temperature is maintained constant for 1 hour to obtain anhydrous Mn3O4. Anhydrous Mn3O4 and LiOH are weighed in a Li:Mn molar ratio of 1.05:1, and nanoAl2O3 is added in an Al:Mn elemental mass ratio of 0.0163:1, and nanomagnesium oxide is added in an Mg:Mn elemental mass ratio of 0.008:1. Alternatively, element M may be added in a fixed proportion, and the element M may be, for example, Nb, Ti, W, Ga, Zr 、Y It is at least one of V, Sr, Mo, Cr, Sn, La, and Ce. A mixture precursor can be obtained by uniformly mixing each of the above substances using a sand mill. The precursor is placed in a corundum crucible and 2m 3 Nitrogen gas is passed through at a rate of 1 / h, the temperature is raised to 940°C at a heating rate of 5°C / min, a constant temperature is maintained for 10 hours, and the mixture is allowed to cool naturally to room temperature to obtain the second cathode active material. However, MnO2 may be used instead of Mn3O4, and the mixing ratio with LiOH may be adjusted according to the Mn content.

[0045] In some embodiments, the positive electrode active material layer may optionally contain a conductive agent and a binder. The specific types of conductive agents and binders are not particularly limited and can be selected as needed. For example, the conductive agent includes, but is not limited to, at least one of conductive graphite, superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers. For example, the binder includes, but is not limited to, at least one of styrene-butadiene rubber (SBR), water-based acrylic resin, carboxymethylcellulose (CMC), polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyvinyl butyral (PVB), ethylene-vinyl acetate copolymer (EVA), and polyvinyl alcohol (PVA).

[0046] In the present invention, the positive electrode is a positive electrode piece, the positive electrode piece further comprises a positive electrode current collector, and the positive electrode active material layer is provided on at least one surface of the positive electrode current collector.

[0047] In some embodiments, the positive electrode current collector can be a metal foil or a porous metal plate, such as a foil or porous plate made of a metal or alloy thereof, such as aluminum, copper, nickel, titanium, or silver. For example, the positive electrode current collector is aluminum foil.

[0048] In some embodiments, the positive electrode current collector has two opposing surfaces in the thickness direction of itself, and the positive electrode active material layer is provided on one or both of the two opposing surfaces of the positive electrode current collector. When the positive electrode active material layer is provided on two surfaces of the positive electrode current collector, it is considered to fall within the scope of protection of the present invention if the parameters of the positive electrode active material layer on either surface satisfy the range of parameters of the present invention.

[0049] Positive electrode pieces can be prepared according to conventional methods in the art. Typically, a first positive electrode active material, a second positive electrode active material, and optional conductive agents and binders are dispersed in a solvent to form a uniform positive electrode slurry, the solvent may be N-methylpyrrolidone (NMP). The positive electrode slurry is applied onto a positive electrode current collector, and positive electrode pieces are obtained through processes such as drying and cold pressing.

[0050] The positive electrode piece of the present invention may include other functional layers besides the positive electrode active material layer. For example, in some embodiments, the positive electrode piece of the present invention further includes a conductive undercoat layer (e.g., consisting of a conductive agent and a binder), the conductive undercoat layer sandwiched between the positive electrode current collector and the positive electrode active material layer and provided on the surface of the positive electrode current collector. In other embodiments, the positive electrode piece of the present invention further includes a protective layer covering the surface of the positive electrode active material layer.

[0051] In the present invention, the electrolyte plays a role in conducting active ions between the positive electrode and the negative electrode.

[0052] In some embodiments, the electrolyte includes an additive, which may include a fluorocarbonate and / or an inorganic lithium salt. For example, the additive may include both a fluorocarbonate and an inorganic lithium salt, or either a fluorocarbonate or an inorganic lithium salt.

[0053] In some embodiments, the fluorocarbonate comprises at least one of fluoroethylene carbonate and fluoropropylene carbonate.

[0054] In some embodiments, the inorganic lithium salt comprises at least one of lithium difluorophosphate and lithium tetrafluoroborate.

[0055] The additives contained in the electrolyte of the present invention help to form a dense and stable interfacial film on the surface of the positive electrode active material, further enhancing protection for the positive electrode active material, suppressing side reactions between the electrolyte and the positive electrode active material, reducing interfacial impedance, and improving the high-temperature cycle characteristics of the electrochemical apparatus.

[0056] In some embodiments, the mass fraction of the additive is 0.01% to 10% of the mass of the electrolyte. The mass fractions of the additive are 0.05%, 0.1%, 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7% It is 8%, 10%, or within the range of any of the above numbers.

[0057] In this invention, when the mass fraction of the additive in the electrolyte is within an appropriate range, it helps to form an interfacial film of appropriate thickness on the surface of the positive electrode active material, while simultaneously having low impedance, which is advantageous for improving the cycle characteristics of the electrochemical apparatus. If the mass fraction of the additive is too low, the formation of the interfacial film on the surface of the positive electrode active material will be insufficient, affecting the performance of the electrochemical apparatus. If the mass fraction of the film-forming additive is too high, the impedance of the electrolyte increases, the migration rate of active ions decreases, and the high-temperature cycle characteristics of the electrochemical apparatus will be affected.

[0058] In some examples, the mass fraction of fluorocarbonate may be as low as 0.01% to 8%, which can further improve the high-temperature cycling characteristics of the electrochemical apparatus.

[0059] In some examples, the mass fraction of fluorocarbonate may be as low as 0.01% to 5%, which can further improve the high-temperature cycling characteristics of the electrochemical apparatus.

[0060] In some embodiments, the mass fraction of the inorganic lithium salt may be 0.01% to 3%, which can further improve the high-temperature cycle characteristics of the electrochemical apparatus.

[0061] In some embodiments, the mass fraction of the inorganic lithium salt may be 0.01% to 1.5%, which can further improve the high-temperature cycle characteristics of the electrochemical apparatus.

[0062] In some embodiments, the electrolyte includes an organic solvent and other optional additives. The types of organic solvents and other additives are not particularly limited and can be selected as needed.

[0063] In some embodiments, the organic solvent may include, but is not limited to, at least one of the following: ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butylene carbonate (BC), fluoroethylene carbonate (FEC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), ethyl methyl sulfone (EMS), and diethyl sulfone (ESE). The above organic solvents may be used individually or in combination of two or more. Optionally, two or more of the above organic solvents may be used in combination.

[0064] In some embodiments, the other additives may include additives that can improve certain performance characteristics of the battery, such as additives that improve the overcharge performance of the battery, or additives that improve the high-temperature or low-temperature performance of the battery.

[0065] The electrolyte can be prepared according to conventional methods in the art. For example, an electrolyte can be obtained by uniformly mixing an additive, an organic solvent, and any other additives. The order in which each material is added is not particularly limited, but for example, an electrolyte can be obtained by adding an additive and any other additives to an organic solvent and mixing them uniformly.

[0066] In the present invention, the negative electrode is a negative electrode piece, which may be a metallic lithium piece or an electrode piece comprising a negative electrode current collector and a negative electrode active material layer provided on at least one surface of the negative electrode current collector. The negative electrode active material layer typically comprises a negative electrode active material, as well as optional conductive agents, binders, and thickeners.

[0067] The materials, structure, and manufacturing methods of the negative electrode pieces used in the present invention may include any prior art known techniques.

[0068] The specific type of negative electrode active material is not particularly limited and can be selected as needed. Examples of negative electrode active materials include natural graphite, artificial graphite, mesocarbon microbeads (MCMB), hard carbon, soft carbon, silicon, silicon-carbon composite, SiO, Li-Sn alloy, Li-Sn-O alloy, Sn, SnO, SnO2, and spinel-structured Li4Ti5O 12 This includes, but is not limited to, at least one of the following: a Li-Al alloy.

[0069] The specific type of conductive agent is not particularly limited and can be selected as needed. For example, the conductive agent includes, but is not limited to, at least one of conductive graphite, superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0070] The specific type of binder is not particularly limited and can be selected as needed. For example, the binder includes, but is not limited to, at least one of styrene-butadiene rubber (SBR), polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyvinyl butyral (PVB), water-based acrylic resin, and carboxymethylcellulose.

[0071] The specific type of thickener is not limited and can be selected as needed. For example, a thickener such as sodium carboxymethylcellulose (CMC) is used. -Na This includes, but is not limited to, ) .

[0072] However, the present invention is not limited to the above materials, and the negative electrode piece of the present invention may also use other known materials used as negative electrode active materials, conductive agents, binders, and thickeners.

[0073] In some embodiments, the negative electrode current collector has two opposing surfaces in the thickness direction of itself, Negative electrode active material layer It is provided on either or both of the two opposing surfaces of the negative electrode current collector.

[0074] The negative electrode current collector can be made of metal foil or a porous metal plate, for example, a foil or porous plate made of a metal such as copper, nickel, titanium, or iron, or an alloy thereof. For example, the negative electrode current collector is made of copper foil.

[0075] The negative electrode pieces can be prepared according to conventional methods in the art. Typically, a negative electrode active material, along with any conductive agent, binder, and thickener, is dispersed in a solvent to form a uniform negative electrode slurry, the solvent of which may be N-methylpyrrolidone (NMP) or deionized water. The negative electrode slurry is then applied onto a negative electrode current collector, and negative electrode pieces are obtained through processes such as drying and cold pressing.

[0076] The negative electrode piece of the present invention may include other functional layers besides the negative electrode active material layer. For example, in some embodiments, the negative electrode piece of the present invention further includes a conductive undercoat layer (e.g., consisting of a conductive agent and a binder), the conductive undercoat layer sandwiched between the negative electrode current collector and the negative electrode active material layer and provided on the surface of the negative electrode current collector. In other embodiments, the negative electrode piece of the present invention further includes a protective layer covering the surface of the negative electrode active material layer.

[0077] In the present invention, the electrochemical apparatus further includes a separator. The separator is provided between a positive electrode piece and a negative electrode piece and primarily serves to prevent short circuits between the positive and negative electrodes, while also allowing active ions to pass through. The type of separator in the present invention is not particularly limited, and any known porous separator having good chemical and mechanical stability can be used.

[0078] In some embodiments, the separator material may include, but is not limited to, at least one of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator may be a single-layer film or a multilayer composite film. If the separator is a multilayer composite film, the materials of each layer may be the same or different. In some embodiments, a ceramic coating or a metal oxide coating may be provided on the separator.

[0079] electronic equipment A second embodiment of the present invention provides an electronic device, which includes an electrochemical device according to a first embodiment of the present invention, the electrochemical device being used as a power source in the electronic device.

[0080] The electronic device of the present invention is not particularly limited and may be any known electronic device used in the prior art. In some embodiments, the electronic device may include, but is not limited to, a notebook computer, a pen-input computer, a mobile computer, an e-book player, a mobile phone, a portable facsimile, a portable copier, a portable printer, a stereo headset, a video recorder, an LCD television, a portable cleaner, a portable CD player, a MiniDisc, a transceiver, an electronic organizer, a calculator, a memory card, a portable tape recorder, a radio, a backup power supply, a motor, an automobile, a motorcycle, an electric assist bicycle, a bicycle, lighting fixtures, toys, game consoles, clocks, power tools, flashlights, cameras, large household storage batteries, and lithium-ion capacitors.

[0081] Examples Since various modifications and changes within the scope disclosed in the present invention will be apparent to those skilled in the art, the following examples will more specifically illustrate the contents disclosed in the present invention, and these examples are for illustrative purposes only. Unless otherwise specified, all parts, percentages, and ratios reported in the following examples are by mass. All reagents used in the examples are commercially available or can be synthesized by conventional methods and can be used directly without requiring further processing. The equipment used in the examples is also commercially available.

[0082] Example 1 Preparation of positive electrode pieces The first positive electrode active material, LiFePO4, and the second positive electrode active material were uniformly mixed in a mass ratio of 92:8 and sintered in a nitrogen atmosphere at 300°C for 2 hours to obtain the positive electrode active material. The manufacturing process for the second positive electrode active material was as follows: MnOOH was placed in a corundum crucible and heated to 500°C at a heating rate of 5°C / min in an air atmosphere, and the temperature was maintained at a constant temperature for 1 hour to obtain anhydrous Mn3O4. Anhydrous Mn3O4 and LiOH were weighed in a Li:Mn molar ratio of 1.05:1, nano Al2O3 was added in an elemental mass ratio of Al:Mn of 0.0163:1, and nano magnesium oxide was added in an elemental mass ratio of Mg:Mn of 0.008:1. The above substances were uniformly mixed using a sand mill to obtain a mixture precursor. The precursor was placed in a corundum crucible and sintered for 2 hours. 3 Nitrogen gas was passed through at a rate of 1 / h, the temperature was raised to 940°C at a heating rate of 5°C / min, a constant temperature was maintained for 10 hours, and then it was allowed to cool naturally to room temperature to obtain the second cathode active material.

[0083] The positive electrode active material, the conductive agent Super P, and the binder polyvinylidene fluoride were mixed in a mass ratio of 96:2.4:1.6. N-methylpyrrolidone (NMP) was added, and the mixture was stirred using a vacuum stirrer until the system was homogeneous to obtain a positive electrode slurry. The solid content concentration of the positive electrode slurry was 70 wt%. The positive electrode slurry was uniformly applied to one surface of an aluminum foil positive electrode current collector with a thickness of 10 μm. The aluminum foil was dried at 85°C to obtain a positive electrode piece with a coating layer thickness of 65 μm and a positive electrode active material layer applied to one side. The above procedure was repeated on the other surface of the aluminum foil, i.e., a positive electrode piece with a positive electrode active material layer applied to both sides was obtained. After that, the pieces underwent cold pressing, cutting, and slitting, and were dried for 4 hours under vacuum conditions at 85°C to obtain a positive electrode piece with a standard size of 74 mm × 867 mm.

[0084] Preparation of negative electrode piece The negative electrode active material is artificial graphite, the conductive agent is Super P, and the thickening agent is sodium carboxymethylcellulose (CMC -NaThe material and styrene-butadiene rubber (SBR), which is a binder, were mixed in a mass ratio of 96.4:1.5:0.5:1.6, deionized water was added, and the mixture was stirred under vacuum to obtain a negative electrode slurry. The solid content concentration of the negative electrode slurry was 70 wt%. The negative electrode slurry was uniformly applied to one surface of a copper foil negative electrode current collector with a thickness of 10 μm, and the copper foil was dried at 85°C to obtain a negative electrode piece with a coating layer thickness of 63 μm and a negative electrode active material layer applied to one side. copper foil The above procedure was repeated on the other surface, thus obtaining a negative electrode piece with a negative electrode active material layer coated on both sides. After that, it underwent cold pressing, cutting, and slitting, and was dried for 12 hours under vacuum conditions at 120°C to obtain a negative electrode piece with a standard size of 79 mm × 972 mm.

[0085] Preparation of electrolyte In a glove box under an argon atmosphere with a water content of <10 ppm, linear carbonate DEC, cyclic carbonate EC, and cyclic carbonate PC were mixed in a mass ratio of 1:1:1 to obtain a base solvent. Lithium salt LiPF6 was then added to the base solvent and dissolved, and the mixture was homogeneously mixed. Here, the mass fraction of LiPF6 was 12.5% ​​of the mass of the electrolyte. Alternatively, FEC or lithium difluorophosphate may be further added to the electrolyte.

[0086] Preparation of separators Aqueous polyvinylidene fluoride, aluminum oxide, and polypropylene were mixed in a mass ratio of 1:8:1, added to deionized water, and stirred to obtain a coating layer slurry with a solid content of 50 wt%. The coating layer slurry was uniformly applied to the surface of a 5 μm thick PE film (provided by Celgard), dried at 85°C, and obtained a separator with a 5 μm thick coating layer and a coating layer applied to one side. The above procedure was repeated on the other surface of the separator, i.e., a separator with a coating layer applied to both sides was obtained. Subsequently, the separator was dried and cold-pressed to obtain the final separator.

[0087] Preparation of lithium-ion batteries The positive electrode piece, separator, and negative electrode piece prepared above were stacked in order, with the separator positioned between the positive and negative electrode pieces to act as a separator, and these were wound together to obtain an electrode assembly. The electrode assembly was placed in an aluminum laminate film packaging bag, dried, and then the electrolyte was injected. A lithium-ion battery was obtained by going through processes such as vacuum sealing, standing, chemical conversion, degassing, and edging. The chemical conversion conditions were as follows: Charged to 3.3V with a constant current of 0.02C, then further charged to 3.6V with a constant current of 0.1C. Charged to 4.2V with a constant current of 0.2C, stood for 10 minutes, discharged to 2.5V, stood for 10 minutes, and then further charged to 3.0V with a constant current of 0.2C.

[0088] Examples 2-25 and Comparative Examples 1 The manufacturing method for the lithium-ion battery was the same as in Example 1, except that the relevant parameters in the preparation process of the positive electrode piece and electrolyte were adjusted. Refer to Table 1 for specific parameters, where " / " indicates the absence of the corresponding component.

[0089] Measurement details (1) Measurement of the discharge ratio capacity of lithium-ion batteries A lithium-ion battery was charged to 3.65V with a constant current of 0.2C, then charged again with a constant voltage until the current reached 0.05C, left to stand for 5 minutes, and then discharged to 2.5V with a constant current of 0.2C. This charge-discharge process was repeated twice, and the capacity of the second cycle was recorded as D0. The lithium-ion battery was disassembled, the positive electrode was removed, and the positive electrode was immersed in DMC (dimethyl carbonate) for 30 minutes to remove the electrolyte and by-products from the surface of the positive electrode. After drying in a ventilated hood for 4 hours, the electrode was pulverized in a vacuum at 400°C, and its mass was weighed and recorded as m1.

[0090] The discharge ratio capacity of a lithium-ion battery is D0 / m1.

[0091] (2) Measurement of the cycle characteristics of lithium-ion batteries A lithium-ion battery was charged to 3.65V at 45°C with a constant current of 1C, then charged again with a constant voltage until the current dropped to 0.05C, left to stand for 5 minutes, and then discharged to 2.5V with a constant current of 1C. This constituted one charge-discharge cycle, and the discharge capacity at this time was measured and recorded as D01. The lithium-ion battery was cycled 1000 times according to the above charge-discharge process, and the discharge capacity at the 1000th cycle was measured and recorded as D1.

[0092] The cycle capacity retention rate (%) of a lithium-ion battery is calculated as D1 / D01 × 100%.

[0093] Tables 1 to 3 show Examples 1 to 25 and Comparative Examples. 1 The results of the performance measurement are shown below.

[0094] [Table 1]

[0095] Figure 1 is a Raman spectrum diagram of the positive electrode active material layer of Example 1. As can be seen from Figure 1, the positive electrode active material layer is wavenumber 398cm -1 ~408cm -1 It has a first characteristic peak, wavenumber 940cm -1 ~960cm -1 It has a second characteristic peak, wavenumber 591cm -1 ~611cm -1 It has a third characteristic peak. As can be seen from the measurement results in Table 1, the full width at half maximum of the first characteristic peak of the positive electrode active material layer of Examples 1 to 7 is 20.8 cm². -1 ~29.6cm -1 The full width at half maximum of the second characteristic peak is 10.3 cm. -1Comparative Example 1 does not contain a second positive electrode active material, and therefore its Raman spectrum lacks a first characteristic peak, resulting in low discharge ratio capacity and low high-temperature cycle characteristics. The above measurement results indicate that adding a second positive electrode active material containing aluminum to the positive electrode active material layer can significantly improve the discharge ratio capacity of a lithium-ion battery, and that the synergistic effect of the first and second positive electrode active materials effectively compensates for the loss of active lithium on the surface of the negative electrode active material, effectively increasing the energy density and cycle capacity retention rate of the lithium-ion battery, and improving the high-temperature cycle characteristics of the lithium-ion battery.

[0096] [Table 2]

[0097] As can be seen from the measurement results in Table 2 above, ω Mn / ω Fe As the value increases, the full width at half maximum of the third characteristic peak of the positive electrode active material gradually increases, and within a certain range, ω Mn / ω Fe The larger the value, the stronger the discharge ratio capacity and high-temperature cycle stability of the electrochemical device. However, if the Mn content is too high, when the electrochemical device undergoes charge-discharge cycles at 45°C, Mn will leach out, further affecting the high-temperature cycle characteristics of the electrochemical device.

[0098] [Table 3]

[0099] As can be seen from the measurement results of Examples 1 and 16-25 in Table 3 above, when the electrolyte contains the additive fluorocarbonate and / or inorganic lithium salt, the maintenance rate after 1000 cycles at 45°C is higher than that of Example 1, which does not contain the additive. These results indicate that the additive in the electrolyte can form an interfacial film on the surface of the positive electrode active material, thereby enhancing protection for the positive electrode active material, suppressing side reactions between the electrolyte and the positive electrode active material, reducing interfacial impedance, and further improving the high-temperature cycle characteristics of the electrochemical apparatus.

[0100] As can be seen from the above, the synergistic effect between the first positive electrode active material and the second positive electrode active material containing aluminum significantly increases the capacity per gram of positive electrode active material, thereby increasing the energy density of the electrochemical apparatus and improving its high-temperature cycle characteristics.

[0101] The foregoing describes only specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Within the technical scope disclosed herein, any person skilled in the art can easily conceive of various equivalent modifications or substitutions, and these modifications or substitutions should be included within the scope of protection of the present invention. Accordingly, the scope of protection of the present invention should be the same as the scope of protection of the claims.

Claims

1. An electrochemical apparatus comprising a positive electrode, a negative electrode, and an electrolyte, The positive electrode includes a positive electrode active material layer, the positive electrode active material layer includes a positive electrode active material, and the positive electrode active material includes a first positive electrode active material and a second positive electrode active material. After the electrochemical apparatus has completely discharged, the Raman spectrum of the positive electrode active material layer is measured at wavenumber 398 cm⁻¹. －１ ~408cm －１ It has a first characteristic peak at wavenumber 940 cm⁻¹. －１ ~960cm －１ It has a second characteristic peak, The first positive electrode active material comprises lithium iron phosphate, or a composite material of lithium iron phosphate and carbon. The electrochemical apparatus wherein the second positive electrode active material contains manganese and aluminum elements.

2. After the electrochemical apparatus has completely discharged, the Raman spectrum of the positive electrode active material layer is measured at wavenumber 591 cm⁻¹. －１ ~611cm －１ It has a third characteristic peak, and the full width at half maximum of the said third characteristic peak is 15 cm. －１ ~60cm －１ The electrochemical apparatus according to claim 1.

3. The full width at half maximum of the first characteristic peak is 15 cm －１ to 60 cm －１ and the full width at half maximum of the second characteristic peak is 5 cm －１ to 25 cm －１ and The electrochemical apparatus according to claim 1, wherein the full width at half maximum of the first characteristic peak is greater than the full width at half maximum of the second characteristic peak.

4. The positive electrode active material layer contains manganese, Mass fraction of the element aluminum ω Ａｌ This is 0.1% ≤ ω with respect to the mass of manganese element in the positive electrode active material layer. Ａｌ The electrochemical apparatus according to claim 1, satisfying ≤ 5%.

5. The mass fraction ω of the aforementioned manganese element Ｍｎ and the mass fraction ω of the iron element in the first positive electrode active material Ｆｅ This is 0.01% ≤ ω with respect to the mass of the positive electrode active material layer. Ｍｎ / ω Ｆｅ The electrochemical apparatus according to claim 1, satisfying ≤30%.

6. The positive electrode active material layer contains element M, and element M is at least one selected from the group consisting of Nb, Mg, Ti, W, Ga, Zr, Y, V, Sr, Mo, Cr, Sn, La, and Ce. Mass percentage ω of the element M Ｍ This is 0.03% < ω with respect to the mass of the positive electrode active material layer. Ｍ The electrochemical apparatus according to claim 1, satisfying ≤2.5%.

7. The aforementioned electrolyte contains additives, The aforementioned additive comprises a fluorocarbonate and / or an inorganic lithium salt. The electrochemical apparatus according to claim 1, wherein the mass fraction of the additive is 0.01% to 10% of the mass of the electrolyte.

8. The aforementioned additive is (1) The fluorocarbonate comprises at least one of fluoroethylene carbonate and fluoropropylene carbonate, (2) The inorganic lithium salt comprises at least one of lithium difluorophosphate and lithium tetrafluoroborate, (3) The mass fraction of the fluorocarbonate is 0.01% to 8% of the mass of the electrolyte, (4) The mass fraction of the inorganic lithium salt is 0.01% to 3% of the mass of the electrolyte, The electrochemical apparatus according to claim 7, satisfying at least one of the following conditions.

9. The aforementioned additive is (5) The mass fraction of the fluorocarbonate is 0.01% to 5% of the mass of the electrolyte, (6) The mass fraction of the inorganic lithium salt is 0.01% to 1.5% of the mass of the electrolyte, The electrochemical apparatus according to claim 7, satisfying at least one of the following conditions.

10. The electrochemical apparatus is, (7) The positive electrode active material layer contains manganese and the mass fraction of aluminum ω Ａｌ This is 0.3% ≤ ω with respect to the mass of the manganese element in the positive electrode active material layer. Ａｌ The condition that ≤ 3% is met, (8) The mass fraction of the manganese element ω Ｍｎ and the mass fraction ω of the iron element in the first positive electrode active material Ｆｅ This is 1% ≤ ω with respect to the mass of the positive electrode active material layer. Ｍｎ / ω Ｆｅ The condition that ≤25% is met, (9) The positive electrode active material layer contains element M, and element M is at least one selected from the group consisting of Nb, Mg, Ti, W, Ga, Zr, Y, V, Sr, Mo, Cr, Sn, La and Ce, and the mass fraction of element M is ω Ｍ This is 0.03% < ω with respect to the mass of the positive electrode active material layer. Ｍ The condition must be ≤1.5%, An electrochemical apparatus according to claim 1, satisfying at least one of the following:

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

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