WO2023225857A1 - 电化学装置及电子设备 - Google Patents

电化学装置及电子设备 Download PDF

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WO2023225857A1
WO2023225857A1 PCT/CN2022/094735 CN2022094735W WO2023225857A1 WO 2023225857 A1 WO2023225857 A1 WO 2023225857A1 CN 2022094735 W CN2022094735 W CN 2022094735W WO 2023225857 A1 WO2023225857 A1 WO 2023225857A1
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Prior art keywords
electrochemical device
lithium
positive electrode
molar amount
diffraction peak
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PCT/CN2022/094735
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English (en)
French (fr)
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周墨林
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宁德新能源科技有限公司
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Priority to CN202280010322.7A priority Critical patent/CN116802831A/zh
Priority to PCT/CN2022/094735 priority patent/WO2023225857A1/zh
Publication of WO2023225857A1 publication Critical patent/WO2023225857A1/zh

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/44—Methods for charging or discharging
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/131—Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/139—Processes of manufacture
    • H01M4/1391—Processes of manufacture of electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx

Definitions

  • the present application relates to the field of battery technology, and in particular to an electrochemical device and electronic equipment.
  • Lithium-ion batteries are widely used due to their advantages of high energy density, high power density, high operating voltage, good cycle performance, low self-discharge and good safety.
  • SEI film solid electrolyte interface film
  • the present application provides an electrochemical device and electronic equipment to improve the high-temperature cycle life of the electrochemical device.
  • an electrochemical device including a positive electrode piece, the positive electrode piece including a positive active material layer, the positive active material layer including a first material and a second material; the electrochemical device In the fully charged state, in the XRD diffraction pattern of the positive electrode plate, the diffraction peak A1 of the (003) crystal plane of the second material exists in the range of 18° to 20°, and in the range of 35° to 37° The diffraction peak C1 of the (311) crystal plane of the first material.
  • the diffraction peak A1 is the (003) characteristic peak of lithium manganese composite oxide with a layered crystal structure
  • the diffraction peak C1 is the (311) characteristic peak of the lithium transition metal phosphate compound with an olivine crystal structure.
  • the lithium manganese composite oxide with a layered crystal structure has the characteristics of high first charge specific capacity and low first Coulombic efficiency. When used in conjunction with lithium transition metal phosphate compounds with high first Coulombic efficiency, it can significantly improve the cycle performance of electrochemical devices; On the other hand, when the electrochemical device is first discharged, part of the active lithium is embedded back into the high-voltage range of the lithium-manganese composite oxide with a layered crystal structure.
  • the positive electrode potential decreases.
  • the active lithium embedded back into the high-voltage range of the lithium-manganese composite oxide with a layered crystal structure will be slowly released again.
  • the structural lithium-manganese composite oxide has good structural stability in the fully charged state, and can provide sufficient lithium source for the destruction and regeneration of the SEI film during subsequent cycles, inhibiting the lithium transition metal phosphate compound from being damaged due to high-temperature cycling. Structural damage caused by excessive delithiation, thereby improving the high-temperature cycle life of electrochemical devices.
  • the peak intensity of the diffraction peak A1 is I A1
  • the peak intensity of the diffraction peak C1 is I C1 , satisfying: 3 ⁇ I C1 /I A1 ⁇ 100. In some embodiments, 3 ⁇ I C1 /I A1 ⁇ 55.
  • the diffraction peak B1 is the (104) characteristic peak of the lithium manganese composite oxide with a layered crystal structure, that is, the diffraction peaks A1 and B1 respectively correspond to the (003) crystal plane and the (003) crystal plane of the lithium manganese composite oxide with a layered crystal structure.
  • the first material is a lithium transition metal phosphate compound having an olivine crystal structure
  • the second material is a lithium manganese composite oxide having a layered crystal structure.
  • the second material includes R-3m and C2/m crystal phase structures.
  • the second material includes Mn element, T element, O element, optional Ni element and optional T′ element, the T element includes at least one of Fe or Co;
  • the T' element includes Mg, Al, Ti, V, Cr, Cu, Y, Zr, Nb, Mo, La, Zn, Ga, Ru, Ag, Sn, Au, Ce, Pr, Nd, Sm, Gd or W At least one of; in the second material, the molar amount of the Mn element is n Mn , the molar amount of the T element is n T , the molar amount of the O element is n O , and the molar amount of the Ni element is n O The molar amount is n Ni , the molar amount of the T′ element is n T ′, and the sum of the molar amounts of the Mn element, T element, Ni element and T′ element is n M , satisfying: 0.25 ⁇ n Mn /n M ⁇ 0.85, 0.05 ⁇ n T /n
  • T element Fe and/or Co
  • Adding an appropriate amount of T element (Fe and/or Co) to the second material component makes the structure of the second material more stable after delithiation, and the Mn element in the product after delithiation of the second material has many forms. It is Mn 4+ , so it can effectively suppress the Ginger-Taylor distortion effect of Mn 3+ , reduce the damage to the SEI film caused by the dissolution of Mn elements, and effectively improve the high-temperature cycle life of the electrochemical device.
  • the first material includes Fe element, optional Mn element and optional T′′ element
  • the T′′ element includes Ti, Zr, V, Al, Co, Ni, Cu, Zn, At least one of Mg, Ga, Nb or Cr.
  • the molar amount of the Fe element is m Fe
  • the molar amount of the Mn element is m Mn
  • the molar amount of the T′′ element is m T ′′
  • the sum of the molar amounts of the Fe element, Mn element and T′′ element is m M , satisfying: 0.5 ⁇ m Fe /m M ⁇ 1, 0 ⁇ m Mn /m M ⁇ 0.5, 0 ⁇ m T ′′/m M ⁇ 0.2.
  • the T element includes Fe
  • the molar amount of Fe element is n Fe , which satisfies: 0.05 ⁇ n Fe /n M ⁇ 0.5.
  • the Fe content in the second material is within the above range. Since the ionization energy of Fe 3+ to Fe 4+ is much higher than the ionization energy of Co 3+ to Co 4+ , when cycling under high voltage, the The average valence state is lower than that of Co. On the one hand, it can reduce the oxidation of high-valent metal ions on the electrolyte at the interface. On the other hand, it helps Mn maintain a high valence state, inhibits the Ginger-Taylor distortion effect of Mn, and reduces the risk of Mn dissolution. , at the same time, it can enhance the structural stability of the material and inhibit the migration of transition metals to the lithium layer, thus improving the high-temperature cycle life of the electrochemical device.
  • the average particle diameter of the first material is D 1 and the average particle diameter of the second material is D 2 , satisfying: 3 ⁇ D 2 /D 1 ⁇ 10.
  • the first material has an average particle diameter D 1 of 0.5 ⁇ m to 3 ⁇ m.
  • the second material has an average particle diameter D2 of 4 ⁇ m to 9 ⁇ m.
  • the compacted density of the positive active material layer is P, which satisfies: 1.8g/cm 3 ⁇ P ⁇ 2.7 g/cm 3 .
  • the second material includes any one of the materials represented by Chemical Formula I:
  • T includes Fe or Co At least one of; T' includes Mg, Al, Ti, V, Cr, Cu, Y, Zr, Nb, Mo, La, Zn, Ga, Ru, Ag, Sn, Au, Ce, Pr, Nd, Sm, At least one of Gd or W.
  • the first material includes any one of the materials represented by Chemical Formula II;
  • T′′ includes Ti, Zr, V, Al, Co, Ni, Cu , at least one of Zn, Mg, Ga, Nb or Cr, and A includes at least one of S, N, F, Cl or Br.
  • a second aspect of this application provides an electronic device, including any of the above electrochemical devices.
  • the beneficial effects brought by the technical solution of this application at least include: 1) In this application, by cleverly designing the composition of the positive electrode plate and the cut-off voltage during formation, it has unique XRD diffraction spectrum characteristics, so that the positive electrode plate has unique XRD diffraction spectrum characteristics.
  • the positive electrode plate can have high structural stability during the cycle, especially when an appropriate amount of T element (Fe and/or Co) is added to the second material component, so that the second material can be delithiated during delithiation.
  • the final structure is more stable.
  • the form of Mn element in the product after delithiation of the second material is mostly Mn 4+ .
  • Li 2 NiO 2 materials disclosed in the prior art have high specific capacity, but are expensive and extremely sensitive to air and need to be processed in a drying room.
  • the surface free lithium content of this type of material is extremely high, which can easily cause slurry gel during the slurry mixing process, resulting in poor processing performance.
  • the second material described in this application has low cost and good air stability, and is more compatible with the existing lithium-ion battery production process.
  • Figure 1 is the XRD diffraction pattern of the positive electrode plate in Example 1 of the present application.
  • Figure 2 is an SEM test picture of the second material Li 1.2 Ni 0.133 Fe 0.133 Mn 0.534 O 2 in the positive electrode sheet in Example 1 of the present application.
  • any lower limit can be combined with any upper limit to form an unexpressed range; and any lower limit can be combined with other lower limits to form an unexpressed range, and likewise any upper limit can be combined with any other upper limit to form an unexpressed range.
  • every point or individual value between the endpoints of a range is included in the range.
  • each point or single value may serve as a lower or upper limit on its own in combination with any other point or single value or with other lower or upper limits to form a range not expressly recited.
  • a list of items connected by the term "at least one of,” “at least one of,” “at least one of,” or other similar terms may mean that the listed items any combination of. For example, if items A and B are listed, the phrase “at least one of A and B” means only A; only B; or A and B. In another example, if the items A, B, and C are listed, then the phrase "at least one of A, B, and C” means only A; or only B; only C; A and B (excluding C); A and C (excluding B); B and C (excluding A); or all of A, B and C.
  • the first aspect of the embodiments of the present application provides an electrochemical device, including a positive electrode piece, a negative electrode piece, a separator and an electrolyte.
  • the positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer disposed on the surface of the positive electrode current collector.
  • the positive electrode current collector includes two opposite surfaces in its thickness direction, and the positive electrode active material layer covers the positive electrode current collector. on either or both surfaces.
  • the positive active material layer includes a first material and a second material; when the electrochemical device is fully charged, in the XRD diffraction pattern of the positive electrode piece, the second material is present in the range of 18° to 20°.
  • the diffraction peak A1 of the (003) crystal plane of the material exists in the range of 35° to 37°, and the diffraction peak C1 of the (311) crystal plane of the first material exists.
  • the XRD diffraction pattern of the positive electrode piece was measured after the electrochemical device was disassembled and tested in the designed fully charged state.
  • the diffraction peak A1 is the (003) characteristic peak of the lithium manganese composite oxide with a layered crystal structure
  • the diffraction peak C1 is the olivine crystal structure.
  • the lithium manganese composite oxide with a layered crystal structure has the characteristics of high first charge specific capacity and low first Coulombic efficiency. It is different from the lithium transition with high first Coulombic efficiency.
  • the cycle performance of the electrochemical device can be significantly improved; on the other hand, when the electrochemical device is first discharged, part of the active lithium is back-embedded into the high voltage range of the lithium-manganese composite oxide with a layered crystal structure. , in the subsequent cycle process, as the active lithium continues to be consumed, the positive electrode potential increases simultaneously. At this time, the active lithium embedded back into the high voltage range of the lithium manganese composite oxide with a layered crystal structure will be slowly released again.
  • the lithium-manganese composite oxide with a layered crystal structure has good structural stability in the fully charged state, and can contribute to the destruction and regeneration of the SEI film during subsequent cycles.
  • the peak intensity of the diffraction peak A1 is I A1
  • the peak intensity of the diffraction peak C1 is I C1 , satisfying: 3 ⁇ I C1 /I A1 ⁇ 100.
  • the peak intensity ratio I C1 /I A1 of the diffraction peak C1 and the diffraction peak A1 is 3, 5, 10, 15, 20, 25, 30, 40, 50, 55, 60, 80, 100 Or a range of any two values above. In some embodiments, 3 ⁇ I C1 /I A1 ⁇ 55.
  • diffraction peak B1 of the (104) crystal plane of the second material in the range of 44° to 46°, and the peak intensity of the diffraction peak B1 is I B1 satisfies: 1 ⁇ I A1 /I B1 ⁇ 5.
  • the diffraction peak B1 is The (104) characteristic peak of the lithium manganese composite oxide with a layered crystal structure, that is, the diffraction peaks A1 and B1 respectively correspond to the (003) crystal plane and (104) crystal plane of the lithium manganese composite oxide with a layered crystal structure. Its intensity ratio can reflect the degree of cation mixing in the lithium manganese composite oxide with a layered crystal structure.
  • I A1 /I B1 is within the above range, the degree of cation mixing is low and the structure is more stable, which can further improve electrochemistry. High temperature cycle life of the device.
  • the first material is a lithium transition metal phosphate compound having an olivine crystal structure
  • the second material is a lithium manganese composite oxide having a layered crystal structure.
  • the second material includes R-3m and C2/m crystal phase structures.
  • the second material includes Mn element, T element, O element, optional Ni element and optional T′ element, the T element includes at least one of Fe or Co;
  • the T' element includes Mg, Al, Ti, V, Cr, Cu, Y, Zr, Nb, Mo, La, Zn, Ga, Ru, Ag, Sn, Au, Ce, Pr, Nd, Sm, Gd or W At least one of; in the second material, the molar amount of the Mn element is n Mn , the molar amount of the T element is n T , the molar amount of the O element is n O , and the molar amount of the Ni element is n O The molar amount is n Ni , the molar amount of the T′ element is n T ′, and the sum of the molar amounts of the Mn element, T element, Ni element and T′ element is n M , satisfying: 0.25 ⁇ n Mn /n M ⁇ 0.85, 0.05 ⁇ n T /n
  • T element Fe and/or Co
  • Adding an appropriate amount of T element (Fe and/or Co) to the second material component makes the structure of the second material more stable after delithiation, and the Mn element in the product after delithiation of the second material has many forms. It is Mn 4+ , so it can effectively suppress the Ginger-Taylor distortion effect of Mn 3+ , reduce the damage to the SEI film caused by the dissolution of Mn elements, and effectively improve the high-temperature cycle life of the electrochemical device.
  • the second material includes Mn element, T element and O element; or in another example, the second material includes Mn element, T element, O element and also includes Ni At least one of elements and T′ elements.
  • the molar ratio n Mn /n M of n Mn and n M is a range consisting of 0.25, 0.30, 0.35, 0.4, 0.45, 0.5, 0.6, 0.7, 0.8, 0.85 or any two of the above values.
  • the molar ratio n T /n M between n T and n M is 0.05, 0.06, 0.08, 0.1, 0.2, 0.3, 0.4, 0.5, 0.65 or a range consisting of any two of the above values.
  • the molar ratio n T /n M between n T and n M ranges from 0.05 ⁇ n T /n M ⁇ 0.5.
  • n Ni /n M of n Ni and n M is 0, 0.001, 0.01, 0.05, 0.08, 0.1, 0.2, 0.3, 0.4 or a range consisting of any two of the above values.
  • the molar ratio n T ' /n M between n T' and n M is a range consisting of 0, 0.001, 0.01, 0.02, 0.03, 0.04, 0.05 or any two of the above values.
  • the molar ratio n M /n O of n M and n O is 0.35, 0.40, 0.41, 0.42, 0.43, 0.44, 0.45, 0.475 or a range consisting of any two of the above values.
  • the T element includes Fe
  • the molar amount of Fe element is n Fe , which satisfies: 0.05 ⁇ n Fe /n M ⁇ 0.5.
  • the Fe content in the second material is within the above range. Since the ionization energy of Fe 3+ to Fe 4+ is much higher than the ionization energy of Co 3+ to Co 4+ , when cycling under high voltage, the The average valence state is lower than that of Co. On the one hand, it can reduce the oxidation of high-valent metal ions on the electrolyte at the interface. On the other hand, it helps Mn maintain a high valence state, inhibits the Ginger-Taylor distortion effect of Mn, and reduces the risk of Mn dissolution. , at the same time, it can enhance the structural stability of the material and inhibit the migration of transition metals to the lithium layer, thus improving the high-temperature cycle life of the electrochemical device.
  • the first material includes Fe element, optional Mn element and optional T′′ element
  • the T′′ element includes Ti, Zr, V, Al, Co, Ni, Cu, Zn, At least one of Mg, Ga, Nb or Cr.
  • the molar amount of the Fe element is m Fe
  • the molar amount of the Mn element is m Mn
  • the molar amount of the T′′ element is m T ′′
  • the sum of the molar amounts of the Fe element, the Mn element and the T′′ element is m M , satisfying: 0.5 ⁇ m Fe /m M ⁇ 1, 0 ⁇ m Mn /m M ⁇ 0.5 ,0 ⁇ m T′′ /m M ⁇ 0.2.
  • the first material includes Fe element; or in another example, the first material includes Fe element and also includes at least one of Mn element or T′′ element.
  • the molar ratio m Fe /m M of m Fe and m M is 0.5, 0.6, 0.7, 0.8, 0.9, 1.0 or a range consisting of any two of the above values.
  • the molar ratio m Mn / m M of m Mn and m M is 0, 0.1, 0.2, 0.3, 0.4, 0.5 or a range consisting of any two of the above values.
  • the molar ratio m T ′′/m M between m T′′ and m M is a range consisting of 0, 0.001, 0.01, 0.05, 0.10, 0.15, 0.20 or any two of the above values.
  • the average particle diameter of the first material is D 1 and the average particle diameter of the second material is D 2 , satisfying: 3 ⁇ D 2 /D 1 ⁇ 10.
  • the second material particles can be better surrounded by the first material particles, which can effectively supplement the first material with active lithium while reducing the occurrence of side reactions on its own surface, thus improving the high-temperature cycle life of the electrochemical device.
  • the average particle size is tested using a scanning electron microscope. The specific testing method is to take a sample of the positive active material layer and observe it under a scanning electron microscope (SEM), take SEM photos at a suitable magnification, and use image processing software.
  • SEM scanning electron microscope
  • Average particle size D 2 Average particle size
  • the particle size ratio D 2 /D 1 of D 2 and D 1 is a range consisting of 3, 5, 6, 8, 10 or any two of the above values.
  • the first material has an average particle diameter D 1 of 0.5 ⁇ m to 3 ⁇ m.
  • the average particle diameter D 1 of the first material is a range consisting of 0.5 ⁇ m, 0.8 ⁇ m, 1.0 ⁇ m, 1.5 ⁇ m, 2 ⁇ m, 3 ⁇ m, or any two of the above values.
  • the second material has an average particle diameter D2 of 4 ⁇ m to 9 ⁇ m.
  • the average particle diameter D 2 of the second material is a range consisting of 4 ⁇ m, 5 ⁇ m, 6 ⁇ m, 8 ⁇ m, 9 ⁇ m, or any two of the above values.
  • the compacted density of the cathode active material layer is P, which satisfies: 1.8g/cm 3 ⁇ P ⁇ 2.7 g/cm 3 .
  • the compacted density P of the positive active material layer is 1.8g/cm 3 , 2.0g/cm 3 , 2.2g/cm 3 , 2.5g/cm 3 , 2.7g/cm 3 or any two of the above . A range of values.
  • the volume v of the positive active material layer may be the product of the area S of the positive active material layer and the thickness h of the positive active material layer.
  • the electron and ion transport network between the cathode active material particles in the cathode plate can be further optimized to balance the cycle life and rate performance of the electrochemical device.
  • the second material includes any one of the materials represented by Chemical Formula I:
  • T includes Fe or Co At least one of; T' includes Mg, Al, Ti, V, Cr, Cu, Y, Zr, Nb, Mo, La, Zn, Ga, Ru, Ag, Sn, Au, Ce, Pr, Nd, Sm, At least one of Gd or W.
  • the first material includes any one of the materials represented by Chemical Formula II;
  • T′′ includes Ti, Zr, V, Al, Co, Ni, Cu , at least one of Zn, Mg, Ga, Nb or Cr, and A includes at least one of S, N, F, Cl or Br.
  • the weight ratio of the first material to the second material is 3:1 ⁇ 96:1.
  • the weight percentage of the first material is 75 wt% to 96 wt% based on the total weight of the cathode active material layer.
  • the weight ratio of the first material is 75wt%, 80wt%, 85wt%, 90wt%, 92wt%, 94wt%, 96wt% or a range consisting of any two of the above values.
  • the weight percentage of the second material is 1 wt% to 22 wt% based on the total weight of the cathode active material layer.
  • the weight percentage of the second material is 1wt%, 2wt%, 3wt%, 5wt%, 8wt%, 10wt%, 11wt%, 12wt%, 15wt%, 18wt%, 20wt%, 22wt% Or a range of any two values above.
  • the cathode active material layer further includes a conductive agent and a binder.
  • the weight percentage of the conductive agent is 0.1 wt% to 5 wt% based on the total weight of the cathode active material layer. In some embodiments, the weight percentage of the binder is 0.5 wt% to 5 wt% based on the total weight of the cathode active material layer.
  • the conductive agent includes one or more of graphite, conductive carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene or carbon nanofibers.
  • the binder includes styrene-butadiene rubber (SBR), water-based acrylic resin, carboxymethylcellulose (CMC), polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyvinyl butyral (PVB), ethylene-vinyl acetate copolymer (EVA) or polyvinyl alcohol (PVA).
  • SBR styrene-butadiene rubber
  • CMC carboxymethylcellulose
  • PVDF polyvinylidene fluoride
  • PTFE polytetrafluoroethylene
  • PVB polyvinyl butyral
  • EVA ethylene-vinyl acetate copolymer
  • PVA polyvinyl alcohol
  • the positive electrode current collector includes at least one of a metal foil and a porous metal plate, such as a foil or porous plate using metals such as aluminum, copper, nickel, titanium, silver, or their alloys, such as aluminum foil.
  • the thickness of the positive electrode current collector is 4 ⁇ m to 20 ⁇ m.
  • the positive electrode sheet of the present application can be prepared according to conventional methods in this field.
  • the cathode slurry containing the first material, the second material, the conductive agent and the binder is first coated on at least one surface of the cathode current collector to obtain the cathode active material coating, and is then dried, cold pressed and other processes , that is, the positive electrode piece is obtained.
  • the negative electrode sheet may be a metal lithium sheet, or may include 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 negative active material layer typically includes a negative active material and optionally a conductive agent and a binder.
  • the negative active material includes natural graphite, artificial graphite, mesophase microcarbon beads (MCMB), hard carbon, soft carbon, silicon, silicon-carbon composite, SiO, Li-Sn alloy, Li-Sn-O alloy , one or more of Li-Al alloy or metallic lithium;
  • the conductive agent includes one or more of conductive carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene or carbon nanofibers, or Various; binders include styrene-butadiene rubber (SBR), polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyvinyl butyral (PVB), water-based acrylic resin ) or one or more of carboxymethyl cellulose (CMC).
  • SBR styrene-butadiene rubber
  • PVDF polyvinylidene fluoride
  • PTFE polytetrafluoroethylene
  • PVB polyvinyl butyral
  • the negative electrode current collector may be made of metal foil or porous metal plate, for example, foil or porous plate made of metal such as copper, nickel, titanium or iron or their alloys, such as copper foil.
  • the negative electrode piece can be prepared according to conventional methods in the art.
  • the negative electrode active material and optional conductive agent and binder are dispersed in a solvent, which can be N-methylpyrrolidone (NMP) or deionized water, to form a uniform negative electrode slurry, and the negative electrode slurry is It is coated on the negative electrode current collector, and the negative electrode piece is obtained through processes such as drying and cold pressing.
  • NMP N-methylpyrrolidone
  • deionized water deionized water
  • isolation membrane there is no particular restriction on the above-mentioned isolation membrane. Any well-known porous structure isolation membrane with electrochemical stability and chemical stability can be used, such as glass fiber, non-woven fabric, polyethylene (PE), polypropylene (PP) and polyethylene. Single or multi-layer films of one or more types of vinylidene fluoride (PVDF).
  • PVDF vinylidene fluoride
  • the above-mentioned electrolyte solution includes organic solvent, electrolyte lithium salt and additives.
  • the present invention does not impose specific restrictions on the types, and can be selected according to actual needs.
  • the above-mentioned organic solvents include ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropylene carbonate Ester (DPC), methylpropyl carbonate (MPC), ethylpropyl 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), butyric acid
  • ethyl ester EB
  • 1,4-butyrolactone GBL
  • sulfolane SF
  • MSM dimethyl sulfone
  • EMS methyl ethyl sulfone
  • the above-mentioned electrolyte lithium salt includes LiPF 6 (lithium hexafluorophosphate), LiBF 4 (lithium tetrafluoroborate), LiClO 4 (lithium perchlorate), LiAsF 6 (lithium hexafluoroarsenate), LiFSI (bisfluorosulfonyl Lithium amine), LiTFSI (lithium bistrifluoromethanesulfonyl imide), LiTFS (lithium trifluoromethanesulfonate), LiDFOB (lithium difluoromethanesulfonate), LiBOB (lithium dioxalatoborate), LiPO 2 F 2 (difluoromethanesulfonate)
  • LiDFOP lithium difluorodioxalate phosphate
  • LiTFOP lithium tetrafluorooxalate phosphate
  • the above-mentioned electrolyte may also optionally include other additives, which may be any additives that can be used as lithium-ion secondary batteries.
  • the additives may be vinylene carbonate (VC), ethylene ethylene carbonate (VEC), succinonitrile (SN), adiponitrile (AND), 1,3-propene sultone (PST), One or more of tris(trimethylsilane)phosphate (TMSP) or tris(trimethylsilane)borate (TMSB).
  • the electrochemical device can be prepared according to conventional methods in the art. For example, the above-mentioned positive electrode piece, isolation film and negative electrode piece are stacked in order, so that the isolation film is between the positive electrode piece and the negative electrode piece to play an isolation role, and an electrode assembly is obtained, which can also be wound Finally, the electrode assembly is obtained; the electrode assembly is placed in the packaging shell, the electrolyte is injected and sealed, and the electrochemical device is obtained.
  • the electrochemical device of the present application may include any device that undergoes an electrochemical reaction, and specific examples thereof include all kinds of primary batteries or secondary batteries.
  • the electrochemical device is a lithium secondary battery, including a lithium metal secondary battery, a lithium ion secondary battery, a lithium polymer secondary battery or a lithium ion polymer secondary battery.
  • the electronic device of the present application includes any of the above electrochemical devices of the present application.
  • the electronic device of the present application can be used in, but not limited to, notebook computers, pen input computers, mobile computers, e-book players, portable telephones, portable fax machines, portable copiers, portable printers, stereo headsets, video recorders, LCD TV, portable cleaner, portable CD player, mini CD, transceiver, electronic notepad, calculator, memory card, portable recorder, radio, backup power supply, motor, automobile, motorcycle, power-assisted bicycle, bicycle, lighting equipment , toys, game consoles, clocks, power tools, flashlights, cameras, large household batteries and lithium-ion capacitors, etc.
  • the first material LiFePO 4 , the second material Li 1.2 Ni 0.133 Fe 0.133 Mn 0.534 O 2 , binder (PVDF), and conductive carbon black are mixed, wherein LiFePO 4 , Li 1.2 Ni 0.133 Fe 0.133 Mn 0.534 O 2 , PVDF
  • the weight ratio of conductive carbon black to conductive carbon black is 88.5:8.0:1.5:2.0.
  • EC ethylene carbonate
  • EMC ethyl methyl carbonate
  • DEC diethyl carbonate
  • the positive electrode piece, isolation film, and negative electrode piece are stacked in sequence.
  • the isolation film is a polypropylene (PP) porous film with a thickness of 14 ⁇ m, which plays an isolation role between the positive electrode piece and the negative electrode piece, and is then rolled into Bare battery core: Put the bare battery core into an aluminum-plastic film, inject electrolyte and seal it, and then go through processes such as standing, forming, and shaping to obtain a lithium-ion battery. Among them, the formation process is as follows: perform the first cycle of charge and discharge at 45°C.
  • Example 1 The difference from Example 1 is that the material components in the positive electrode sheet and the relevant parameters in the preparation steps are adjusted, see Table 1 for details.
  • Example 1 The difference from Example 1 is that the material components in the positive electrode sheet and the relevant parameters in the preparation steps are adjusted, see Table 1 for details.
  • the lithium-ion battery After the lithium-ion battery is fully charged, it is disassembled to obtain the positive electrode piece.
  • An X-ray diffraction tester (XPertPro MPD, PANalytical, the Netherlands) is used, and the test conditions are set: Cu K ⁇ radiation
  • the working current is 250mA, continuous scanning is used, the working voltage is 40kV, the scanning range 2 ⁇ is 10° to 70°, the step size is 0.1°, and the scanning speed is 0.2 seconds/step.
  • a Carl Zeiss ZEISS SIGMA-500 field emission scanning electron microscope was used to observe the morphology of the samples and test the average particle size. Take SEM photos at a suitable magnification, use image processing software, randomly count the longest diameters of 50 particles of the first material, and take the average value as the average particle size D 1 of the first material; randomly count 50 particles of the second material The longest diameter, the average value is taken as the average particle diameter D 2 of the second material.
  • Lithium-ion battery 2C rate discharge capacity retention rate (%) 2C rate discharge capacity/0.5C rate discharge capacity ⁇ 100%.
  • the second material containing Fe can further improve the high-temperature cycle life of the lithium-ion battery compared with the second material containing Co. This is because the ionization energy of Fe 3+ to Fe 4+ is much higher than that of Co 3+ to Co 4+ . Therefore, when cycling at high voltage, the average valence state of Fe is higher than the average valence state of Co.
  • Example 22 and Example 23 also contain the first material and the second material
  • the peak intensity ratio I C1 /I A1 of the C1 peak and the A1 peak in their XRD diffraction spectra is also appropriate. within the range, but because the peak intensity ratio I A1 /I B1 of the diffraction peak A1 of the (003) crystal plane and the diffraction peak B1 of the (104) crystal plane of the second material used is not in the range of 1 to 5, The high-temperature cycle performance and rate performance of lithium-ion batteries are both low. This is because the peak intensity ratio I A1 /I B1 can reflect the degree of mixing of cations and the layered crystal structure of lithium-manganese composite oxides with a layered crystal structure.
  • the stability of _ The layered crystal structure of the second material has too high stability, which is not conducive to activation during the first cycle and the extraction of lithium ions during subsequent cycles, which in turn leads to a reduction in the high-temperature cycle performance and rate performance of the lithium-ion battery.

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Abstract

本申请公开了一种电化学装置及电子设备，所述电化学装置包括正极极片，所述正极极片包括正极活性材料层，所述正极活性材料层包括第一材料和第二材料；所述电化学装置在满充状态下，所述正极极片的XRD衍射图谱中，在18°至20°范围内存在所述第二材料(003)晶面的衍射峰A1，在35°至37°范围内存在所述第一材料(311)晶面的衍射峰C1。本申请的电化学装置能够具有改善的高温循环寿命。

Description

电化学装置及电子设备 技术领域
本申请涉及电池技术领域，尤其涉及一种电化学装置及电子设备。
背景技术
锂离子电池因具有能量密度高、功率密度大、工作电压高、循环性能好、自放电低和安全性好等优点而得到广泛的应用。然而，锂离子电池在首次充放电过程中，负极表面形成固态电解质界面膜(SEI膜)会消耗大量的活性锂，造成不可逆容量损失；同时，在后续循环过程中，由于SEI膜的破坏和再生，会进一步消耗活性锂，导致电池循环寿命的衰减。
发明内容
有鉴于此，本申请提供一种电化学装置及电子设备，以改善电化学装置的高温循环寿命。
本申请第一方面，提供了一种电化学装置，包括正极极片，所述正极极片包括正极活性材料层，所述正极活性材料层包括第一材料和第二材料；所述电化学装置在满充状态下，所述正极极片的XRD衍射图谱中，在18°至20°范围内存在所述第二材料(003)晶面的衍射峰A1，在35°至37°范围内存在所述第一材料(311)晶面的衍射峰C1。其中，衍射峰A1为具有层状晶体结构的锂锰复合氧化物的(003)特征峰，衍射峰C1为具有橄榄石型晶体结构的锂过渡金属磷酸化合物的(311)特征峰，一方面，层状晶体结构的锂锰复合氧化物具有首次充电比容量高、首次库伦效率低的特点，其与首次库伦效率高的锂过渡金属磷酸化合物配合使用时，可以显著提升电化学装置的循环性能；另一方面，电化学装置在首次放电时，部分活性锂回嵌至具有层状晶体结构的锂锰复合氧化物的 高电压区间，在后续循环过程中，随着活性锂的持续消耗，正极电位同步升高，此时，回嵌至具有层状晶体结构的锂锰复合氧化物高电压区间的活性锂又会缓释出来，通过正极极片的XRD衍射图谱存在衍射峰A1，具有层状晶体结构的锂锰复合氧化物在满充状态下具有良好的结构稳定性，在后续循环过程中能够为SEI膜的破坏和再生提供充足的锂源，抑制锂过渡金属磷酸化合物在高温循环过程中由于过度脱锂而导致的结构破坏，从而改善电化学装置的高温循环寿命。
在一些实施方式中，所述衍射峰A1的峰强度为I A1，所述衍射峰C1的峰强度为I C1，满足：3≤I C1/I A1≤100。在一些实施方式中，3≤I C1/I A1≤55。
在一些实施方式中，所述正极极片的XRD衍射图谱中，在44°至46°范围内存在所述第二材料(104)晶面的衍射峰B1，所述衍射峰B1的峰强度为I B1，满足：1≤I A1/I B1≤5。其中，衍射峰B1为具有层状晶体结构的锂锰复合氧化物的(104)特征峰，即衍射峰A1和B1分别对应具有层状晶体结构的锂锰复合氧化物的(003)晶面和(104)晶面，其强度比可反映具有层状晶体结构的锂锰复合氧化物中阳离子的混排程度，I A1/I B1在上述范围内，其阳离子混排程度低，结构更稳定，从而能够进一步改善电化学装置的高温循环寿命。
在一些实施方式中，所述第一材料为具有橄榄石型晶体结构的锂过渡金属磷酸化合物；所述第二材料为具有层状晶体结构的锂锰复合氧化物。
在一些实施方式中，所述第二材料包括R-3m和C2/m晶相结构。
在一些实施方式中，所述第二材料包括Mn元素、T元素、O元素、可选的Ni元素以及可选的T′元素，所述T元素包括Fe或Co中的至少一种；所述T′元素包括Mg、Al、Ti、V、Cr、Cu、Y、Zr、Nb、Mo、La、Zn、Ga、Ru、Ag、Sn、Au、Ce、Pr、Nd、Sm、Gd或W中的至少一种；所述第二材料中，所述Mn元素的摩尔量为n Mn，所述T元素的摩尔量为n T，所述O元素的摩尔量为n O，所述Ni元素的摩尔量为n Ni，所述T′元素的摩尔量为n T′，所述Mn元素、T元 素、Ni元素和T′元素的摩尔量之和为n M，满足：0.25≤n Mn/n M≤0.85，0.05≤n T/n M≤0.65，0≤n Ni/n M≤0.4，0≤n T′/n M≤0.05，0.35≤n M/n O≤0.475。在所述第二材料组分中加入适量的T元素(Fe和/或Co)，使得所述第二材料在脱锂后的结构更稳定，第二材料脱锂后产物中Mn元素的形态多为Mn 4+，因此可以有效抑制Mn 3+的姜-泰勒畸变效应，降低了Mn元素的溶出对SEI膜的破坏，能有效提升电化学装置的高温循环寿命。
在一些实施方式中，所述第一材料包括Fe元素、可选的Mn元素以及可选的T″元素，所述T″元素包括Ti、Zr、V、Al、Co、Ni、Cu、Zn、Mg、Ga、Nb或Cr中的至少一种，所述第二材料中，所述Fe元素的摩尔量为m Fe，所述Mn元素的摩尔量为m Mn，所述T″元素的摩尔量为m T″，所述Fe元素、Mn元素和T″元素的摩尔量之和为m M，满足：0.5≤m Fe/m M≤1，0≤m Mn/m M≤0.5，0≤m T″/m M≤0.2。
在一些实施方式中，0.05≤n T/n M≤0.5。
在一些实施方式中，所述T元素包括Fe，所述第二材料中，Fe元素的摩尔量为n Fe，满足：0.05≤n Fe/n M≤0.5。第二材料中的Fe含量在上述范围内，由于Fe 3+到Fe 4+的离子化能远高于Co 3+到Co 4+的离子化能，因此，在高电压下循环时，Fe的平均价态比Co的平均价态低，一方面可降低高价金属离子在界面上对电解液的氧化，另一方面有利于Mn维持高价态，抑制Mn的姜-泰勒畸变效应，降低Mn溶出风险，同时，能够增强材料的结构稳定性，抑制过渡金属向锂层的迁移，从而提升电化学装置的高温循环寿命。
在一些实施方式中，所述第一材料的平均粒径为D 1，所述第二材料的平均粒径为D 2，满足：3≤D 2/D 1≤10。
在一些实施方式中，所述第一材料的平均粒径D 1为0.5μm至3μm。在一些实施方式中，所述第二材料的平均粒径D 2为4μm至9μm。
在一些实施方式中，所述正极活性材料层的压实密度为P，满足：1.8g/cm 3≤P≤2.7g/cm 3。
在一些实施方式中，所述第二材料包括具有化学式Ⅰ所示材料中的任一种：
Li 2-eNi aT bMn cT′ dO 2   化学式Ⅰ
其中，0≤a≤0.35，0<b≤0.6，0.25≤c≤0.65，0≤d≤0.05，0.7≤a+b+c+d≤0.95，0.7≤e≤0.95，T包括Fe或Co中的至少一种；T′包括Mg、Al、Ti、V、Cr、Cu、Y、Zr、Nb、Mo、La、Zn、Ga、Ru、Ag、Sn、Au、Ce、Pr、Nd、Sm、Gd或W中的至少一种。
在一些实施方式中，所述第一材料包括具有化学式Ⅱ所示材料中的任一种；
Li xFe yMn zT″ 1-y-zPO 4-tA t    化学式Ⅱ
其中，0.6≤x≤1.2，0.5≤y≤1，0≤z≤0.5，0.8≤y+z≤1，0≤t≤0.2，T″包括Ti、Zr、V、Al、Co、Ni、Cu、Zn、Mg、Ga、Nb或Cr中的至少一种，A包括S、N、F、Cl或Br中的至少一种。
本申请第二方面，提供了一种电子设备，包括上述任意一种电化学装置。
本申请的技术方案带来的有益效果至少包括：1)在本申请中，通过巧妙设计所述正极极片的组成以及化成时的截止电压，使之具有独特的XRD衍射谱特征，从而使所述正极极片在循环过程中能够具有较高的结构稳定性，尤其是在所述第二材料组分中加入适量的T元素(Fe和/或Co)，使得所述第二材料在脱锂后的结构更稳定，所述第二材料脱锂后产物中Mn元素的形态多为Mn 4+，因此可以有效抑制Mn 3+的姜-泰勒畸变效应，降低了Mn元素的溶出对SEI膜的破坏，能有效提升锂离子电池的高温循环寿命。2)现有技术中公开的Li 2NiO 2类材料，这类材料的比容量高，但其价格昂贵，且对空气极其敏感，需要在干燥房中加工。此外，该类材料的表面游离锂含量极高，在调浆过程极易造成浆料凝胶，加工性能很差。本申请所述的第二材料成本低廉且空气稳定性好，与现有锂离子电池的 生产工艺兼容性更高。
附图说明
为了更清楚地说明本申请实施例中的技术方案，下面将对实施例描述中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图仅仅是本申请的一些实施例，对于本领域技术人员来讲，还可以根据这些附图获得其他的附图。
图1为本申请实施例1的正极极片的XRD衍射图谱；
图2为本申请实施例1的正极极片中第二材料Li 1.2Ni 0.133Fe 0.133Mn 0.534O 2的SEM测试图。
具体实施方式
为了使本申请的目的、技术方案及优点更加清楚明白，以下结合附图及实施例，对本申请进行进一步详细说明。应当理解，此处所描述的具体实施例仅仅用以解释本申请，并不用于限制本申请。
为了简便，本文仅明确地公开了一些数值范围。然而，任意下限可以与任何上限组合形成未明确记载的范围；以及任意下限可以与其它下限组合形成未明确记载的范围，同样任意上限可以与任意其它上限组合形成未明确记载的范围。此外，尽管未明确记载，但是范围端点间的每个点或单个数值都包含在该范围内。因而，每个点或单个数值可以作为自身的下限或上限与任意其它点或单个数值组合或与其它下限或上限组合形成未明确记载的范围。
在具体实施方式及权利要求书中，由术语“中的至少一者”、“中的至少一个”、“中的至少一种”或其他相似术语所连接的项目的列表可意味着所列项目的任何组合。例如，如果列出项目A及B，那么短语“A及B中的至少一者”意味着仅A；仅B；或A及B。在另一实例中，如果列出项目A、B及C，那么 短语“A、B及C中的至少一者”意味着仅A；或仅B；仅C；A及B(排除C)；A及C(排除B)；B及C(排除A)；或A、B及C的全部。
电化学装置
本申请实施例第一方面提供一种电化学装置，包括正极极片、负极极片、隔离膜和电解液。
正极极片
正极极片包括正极集流体以及设置于所述正极集流体表面的正极活性材料层，作为一个示例，正极集流体在自身厚度方向上包括相对的两个表面，正极活性材料层覆盖于正极集流体的两个表面中的任意一者或两者上。
所述正极活性材料层包括第一材料和第二材料；所述电化学装置在满充状态下，所述正极极片的XRD衍射图谱中，在18°至20°范围内存在所述第二材料(003)晶面的衍射峰A1，在35°至37°范围内存在所述第一材料(311)晶面的衍射峰C1。所述正极极片的XRD衍射图谱为所述电化学装置在设计满充状态下，将所述正极极片拆解后进行测试的。
本申请实施例所述的正极极片的XRD衍射图谱中，其中，衍射峰A1为具有层状晶体结构的锂锰复合氧化物的(003)特征峰，衍射峰C1为具有橄榄石型晶体结构的锂过渡金属磷酸化合物的(311)特征峰，一方面，具有层状晶体结构的锂锰复合氧化物具有首次充电比容量高、首次库伦效率低的特点，其与首次库伦效率高的锂过渡金属磷酸化合物配合使用时，可以显著提升电化学装置的循环性能；另一方面，电化学装置在首次放电时，部分活性锂回嵌至具有层状晶体结构的锂锰复合氧化物的高电压区间，在后续循环过程中，随着活性锂的持续消耗，正极电位同步升高，此时，回嵌至具有层状晶体结构的锂锰复合氧化物高电压区间的活性锂又会缓释出来，通过满足正极极片的XRD衍射图谱存在衍射 峰A1，具有层状晶体结构的锂锰复合氧化物在满充状态下具有良好的结构稳定性，在后续循环过程中能够为SEI膜的破坏和再生提供充足的锂源，抑制锂过渡金属磷酸化合物在高温循环过程中由于过度脱锂而导致的结构破坏，从而改善电化学装置的高温循环寿命。
在一些实施例中，所述衍射峰A1的峰强度为I A1，所述衍射峰C1的峰强度为I C1，满足：3≤I C1/I A1≤100。
示例性地，所述衍射峰C1和所述衍射峰A1的峰强比I C1/I A1为3、5、10、15、20、25、30、40、50、55、60、80、100或上述任意两个值组成的范围。在一些实施例中，3≤I C1/I A1≤55。
在一些实施例中，所述正极极片的XRD衍射图谱中，在44°至46°范围内存在所述第二材料(104)晶面的衍射峰B1，所述衍射峰B1的峰强度为I B1，满足：1≤I A1/I B1≤5。
本发明实施例所述的正极极片的XRD衍射图谱中，除了存在上述所述的衍射峰C1和衍射峰A1，在44°至46°范围内还存在衍射峰B1，其中，衍射峰B1为具有层状晶体结构的锂锰复合氧化物的(104)特征峰，即衍射峰A1和B1分别对应具有层状晶体结构的锂锰复合氧化物的(003)晶面和(104)晶面，其强度比可反映具有层状晶体结构的锂锰复合氧化物中阳离子的混排程度，I A1/I B1在上述范围内，其阳离子混排程度低，结构更稳定，从而能够进一步改善电化学装置的高温循环寿命。
在一些实施例中，所述第一材料为具有橄榄石型晶体结构的锂过渡金属磷酸化合物；所述第二材料为具有层状晶体结构的锂锰复合氧化物。
在一些实施例中，所述第二材料包括R-3m和C2/m晶相结构。
在一些实施例中，所述第二材料包括Mn元素、T元素、O元素、可选的Ni元素以及可选的T′元素，所述T元素包括Fe或Co中的至少一种；所述T′元 素包括Mg、Al、Ti、V、Cr、Cu、Y、Zr、Nb、Mo、La、Zn、Ga、Ru、Ag、Sn、Au、Ce、Pr、Nd、Sm、Gd或W中的至少一种；所述第二材料中，所述Mn元素的摩尔量为n Mn，所述T元素的摩尔量为n T，所述O元素的摩尔量为n O，所述Ni元素的摩尔量为n Ni，所述T′元素的摩尔量为n T′，所述Mn元素、T元素、Ni元素和T′元素的摩尔量之和为n M，满足：0.25≤n Mn/n M≤0.85，0.05≤n T/n M≤0.65，0≤n Ni/n M≤0.4，0≤n T′/n M≤0.05，0.35≤n M/n O≤0.475。在所述第二材料组分中加入适量的T元素(Fe和/或Co)，使得所述第二材料在脱锂后的结构更稳定，第二材料脱锂后产物中Mn元素的形态多为Mn 4+，因此可以有效抑制Mn 3+的姜-泰勒畸变效应，降低了Mn元素的溶出对SEI膜的破坏，能有效提升电化学装置的高温循环寿命。
可选地，在一个示例中，所述第二材料包括Mn元素、T元素和O元素；或者在另一个示例中，所述第二材料包括Mn元素、T元素、O元素，并且还包括Ni元素、T′元素中的至少一种。
示例性地，n Mn和n M的摩尔比n Mn/n M为0.25、0.30、0.35、0.4、0.45、0.5、0.6、0.7、0.8、0.85或上述任意两个值组成的范围。
示例性地，n T和n M的摩尔比n T/n M为0.05、0.06、0.08、0.1、0.2、0.3、0.4、0.5、0.65或上述任意两个值组成的范围。在一些实施例中，n T和n M的摩尔比n T/n M的取值范围为0.05≤n T/n M≤0.5。
示例性地，n Ni和n M的摩尔比n Ni/n M为0、0.001、0.01、0.05、0.08、0.1、0.2、0.3、0.4或上述任意两个值组成的范围。
示例性地，n T′和n M的摩尔比n T′/n M为0、0.001、0.01、0.02、0.03、0.04、0.05或上述任意两个值组成的范围。
示例性地，n M和n O的摩尔比n M/n O为0.35、0.40、0.41、0.42、0.43、0.44、0.45、0.475或上述任意两个值组成的范围。
在一些实施例中，所述T元素包括Fe，所述第二材料中，Fe元素的摩尔量为n Fe，满足：0.05≤n Fe/n M≤0.5。第二材料中的Fe含量在上述范围内，由于Fe 3+到Fe 4+的离子化能远高于Co 3+到Co 4+的离子化能，因此，在高电压下循环时，Fe的平均价态比Co的平均价态低，一方面可降低高价金属离子在界面上对电解液的氧化，另一方面有利于Mn维持高价态，抑制Mn的姜-泰勒畸变效应，降低Mn溶出风险，同时，能够增强材料的结构稳定性，抑制过渡金属向锂层的迁移，从而提升电化学装置的高温循环寿命。
在一些实施例中，所述第一材料包括Fe元素、可选的Mn元素以及可选的T″元素，所述T″元素包括Ti、Zr、V、Al、Co、Ni、Cu、Zn、Mg、Ga、Nb或Cr中的至少一种，所述第二材料中，所述Fe元素的摩尔量为m Fe，所述Mn元素的摩尔量为m Mn，所述T″元素的摩尔量为m T″，所述Fe元素、所述Mn元素和所述T″元素的摩尔量之和为m M，满足：0.5≤m Fe/m M≤1，0≤m Mn/m M≤0.5，0≤m T″/m M≤0.2。
可选地，在一个示例中，所述第一材料包括Fe元素；或者在另一个示例中，所述第一材料包括Fe元素，还包括Mn元素或T″元素中的至少一种。
示例性地，m Fe和m M的摩尔比m Fe/m M为0.5、0.6、0.7、0.8、0.9、1.0或上述任意两个值组成的范围。
示例性地，m Mn和m M的摩尔比m Mn/m M为0、0.1、0.2、0.3、0.4、0.5或上述任意两个值组成的范围。
示例性地，m T″和m M的摩尔比m T″/m M为0、0.001、0.01、0.05、0.10、0.15、0.20或上述任意两个值组成的范围。
在一些实施例中，所述第一材料的平均粒径为D 1，所述第二材料的平均粒径为D 2，满足：3≤D 2/D 1≤10。此时，第二材料颗粒能够更好地被第一材料颗粒所包围，在高效为第一材料补充活性锂的同时，能够降低自身表面副反应的发 生，从而提升电化学装置的高温循环寿命。具体地，平均粒径的测试方法采用扫描电子显微镜进行测试，具体测试方法为取正极活性材料层样品在扫描电子显微镜(SEM)下观察，在合适的倍率下拍摄SEM照片，使用图像处理软件，随机统计50个第一材料颗粒的最长直径，取其平均值作为第一材料的平均粒径D 1；随机统计50个第二材料颗粒的最长直径，取其平均值作为第二材料的平均粒径D 2。
示例性地，D 2和D 1的粒径比D 2/D 1为3、5、6、8、10或上述任意两个值组成的范围。
在一些实施例中，所述第一材料的平均粒径D 1为0.5μm至3μm。示例性地，所述第一材料的平均粒径D 1为0.5μm、0.8μm、1.0μm、1.5μm、2μm、3μm或上述任意两个值组成的范围。
在一些实施例中，所述第二材料的平均粒径D 2为4μm至9μm。示例性地，所述第二材料的平均粒径D 2为4μm、5μm、6μm、8μm、9μm或上述任意两个值组成的范围。
在一些实施例中，所述正极活性材料层的压实密度为P，满足：1.8g/cm 3≤P≤2.7g/cm 3。示例性地，所述正极活性材料层的压实密度为P为1.8g/cm 3、2.0g/cm 3、2.2g/cm 3、2.5g/cm 3、2.7g/cm 3或上述任意两个值组成的范围。
压实密度P可以通过公式P＝m/v计算得出，式中m为正极活性材料层的重量，单位为g；v为正极活性材料层的体积，单位为cm 3。其中，正极活性材料层的体积v可以是正极活性材料层的面积S与正极活性材料层的厚度h之积。
通过对正极活性材料层的压实密度P进行约束，能够进一步优化正极极片中正极活性材料颗粒之间的电子和离子传输网络，平衡电化学装置的循环寿命和倍率性能。
在一些实施例中，所述第二材料包括具有化学式Ⅰ所示材料中的任一种：
Li 2-eNi aT bMn cT′ dO 2    化学式Ⅰ
其中，0≤a≤0.35，0<b≤0.6，0.25≤c≤0.65，0≤d≤0.05，0.7≤a+b+c+d≤0.95，0.7≤e≤0.95；T包括Fe或Co中的至少一种；T′包括Mg、Al、Ti、V、Cr、Cu、Y、Zr、Nb、Mo、La、Zn、Ga、Ru、Ag、Sn、Au、Ce、Pr、Nd、Sm、Gd或W中的至少一种。
在一些实施例中，所述第一材料包括具有化学式Ⅱ所示材料中的任一种；
Li xFe yMn zT″ 1-y-zPO 4-tA t   化学式Ⅱ
其中，0.6≤x≤1.2，0.5≤y≤1，0≤z≤0.5，0.8≤y+z≤1，0≤t≤0.2，T″包括Ti、Zr、V、Al、Co、Ni、Cu、Zn、Mg、Ga、Nb或Cr中的至少一种，A包括S、N、F、Cl或Br中的至少一种。
在一些实施例中，所述第一材料和所述第二材料的的重量比为3:1～96:1。通过控制正极极片中所述第一材料含量高于所述第二材料含量，使得正极极片中的大部分为所述第一材料，结构稳定性更高，可减少循环中的容量损失和阻抗增加。
在一些实施例中，基于所述正极活性材料层的总重量，所述第一材料的重量百分比为75wt％～96wt％。示例性地，所述第一材料的重量比为75wt％、80wt％、85wt％、90wt％、92wt％、94wt％、96wt％或上述任意两个值组成的范围。
在一些实施例中，基于所述正极活性材料层的总重量，所述第二材料的重量百分含量为1wt％～22wt％。示例性地，所述第二材料的重量百分含量为1wt％、2wt％、3wt％、5wt％、8wt％、10wt％、11wt％、12wt％、15wt％、18wt％、20wt％、22wt％或上述任意两个值组成的范围。
在一些实施例中，所述正极活性材料层还包括导电剂和粘结剂。
在一些实施例中，基于所述正极活性材料层的总重量，所述导电剂的重量百分比为0.1wt％～5wt％。在一些实施例中，基于所述正极活性材料层的总重量，所述粘结剂的重量百分比为0.5wt％～5wt％。
示例性地，所述导电剂包括石墨、导电碳、乙炔黑、炭黑、科琴黑、碳点、碳纳米管、石墨烯或碳纳米纤维中一种或多种。
示例性地，所述粘结剂包括丁苯橡胶(SBR)、水性丙烯酸树脂(water based acrylic resin)、羧甲基纤维素(CMC)、聚偏二氟乙烯(PVDF)、聚四氟乙烯(PTFE)、聚乙烯醇缩丁醛(PVB)、乙烯-醋酸乙烯酯共聚物(EVA)或聚乙烯醇(PVA)中的一种或多种。
示例性地，所述正极集流体包括金属箔材、多孔金属板中的至少一者，例如使用铝、铜、镍、钛或银等金属或它们的合金的箔材或多孔板，如铝箔。可选地，所述正极集流体的厚度为4μm～20μm。
本申请的正极极片可以按照本领域常规方法制备。例如先将包含第一材料、第二材料、导电剂和粘结剂的正极浆料涂布于正极集流体的至少一个表面上，获得正极活性材料涂层，之后经过烘干、冷压等工序，即得到正极极片。
其他
负极极片可以是金属锂片，也可以是包括负极集流体及设置于负极集流体至少一个表面上的负极活性材料层。
负极活性材料层通常包括负极活性材料以及可选的导电剂和粘结剂。
示例性地，负极活性材料包括天然石墨、人造石墨、中间相微碳球(MCMB)、硬碳、软碳、硅、硅-碳复合物、SiO、Li-Sn合金、Li-Sn-O合金、Li-Al合金或金属锂中的一种或多种；导电剂包括导电碳、乙炔黑、炭黑、科琴黑、碳点、碳纳米管、石墨烯或碳纳米纤维中的一种或多种；粘结剂包括丁苯橡胶(SBR)、聚偏二氟乙烯(PVDF)、聚四氟乙烯(PTFE)、聚乙烯醇缩丁醛(PVB)、水性丙烯酸树脂(water-based acrylic resin)或羧甲基纤维素(CMC)中的一种或多种。但本申请并不限定于这些材料，本申请还可以使用可被用作锂离子电池负 极活性材料、导电剂和粘结剂的其它材料。
示例性地，负极集流体可以使用金属箔材或多孔金属板等材料，例如使用铜、镍、钛或铁等金属或它们的合金的箔材或多孔板，如铜箔。
负极极片可以按照本领域常规方法制备。示例性地，将负极活性材料及可选的导电剂和粘结剂分散于溶剂中，溶剂可以是N-甲基吡咯烷酮(NMP)或去离子水，形成均匀的负极浆料，将负极浆料涂覆在负极集流体上，经烘干、冷压等工序得到负极极片。
对上述隔离膜没有特别的限制，可以选用任意公知的具有电化学稳定性和化学稳定性的多孔结构隔离膜，例如玻璃纤维、无纺布、聚乙烯(PE)、聚丙烯(PP)及聚偏二氟乙烯(PVDF)中的一种或多种的单层或多层薄膜。
上述电解液包括有机溶剂，电解质锂盐和添加剂。本发明对其种类不做具体限制，可以根据实际需求进行选择。
示例性地，上述有机溶剂包括为碳酸乙烯酯(EC)、碳酸丙烯酯(PC)、碳酸甲乙酯(EMC)、碳酸二乙酯(DEC)、碳酸二甲酯(DMC)、碳酸二丙酯(DPC)、碳酸甲丙酯(MPC)、碳酸乙丙酯(EPC)、碳酸丁烯酯(BC)、氟代碳酸乙烯酯(FEC)、甲酸甲酯(MF)、乙酸甲酯(MA)、乙酸乙酯(EA)、乙酸丙酯(PA)、丙酸甲酯(MP)、丙酸乙酯(EP)、丙酸丙酯(PP)、丁酸甲酯(MB)、丁酸乙酯(EB)、1，4-丁内酯(GBL)、环丁砜(SF)、二甲砜(MSM)、甲乙砜(EMS)或二乙砜(ESE)中的一种或多种，优选为两种以上。
示例性地，上述电解质锂盐包括LiPF 6(六氟磷酸锂)、LiBF 4(四氟硼酸锂)、LiClO 4(高氯酸锂)、LiAsF 6(六氟砷酸锂)、LiFSI(双氟磺酰亚胺锂)、LiTFSI(双三氟甲磺酰亚胺锂)、LiTFS(三氟甲磺酸锂)、LiDFOB(二氟草酸硼酸锂)、LiBOB(二草酸硼酸锂)、LiPO 2F 2(二氟磷酸锂)、LiDFOP(二 氟二草酸磷酸锂)或LiTFOP(四氟草酸磷酸锂)中的一种或多种。
上述电解液中还可选地包括其它添加剂，其可以是任意可被用作锂离子二次电池的添加剂，本发明不做具体限制，可以根据实际需求进行选择。作为示例，添加剂可以是碳酸亚乙烯酯(VC)、碳酸乙烯亚乙酯(VEC)、丁二腈(SN)、己二腈(AND)、1，3-丙烯磺酸内酯(PST)、三(三甲基硅烷)磷酸酯(TMSP)或三(三甲基硅烷)硼酸酯(TMSB)中的一种或多种。
电化学装置可以按照本领域常规方法制备。示例性地，将上述正极极片、隔离膜及负极极片按顺序堆叠好，使隔离膜处于正极极片与负极极片之间起到隔离的作用，得到电极组件，也可以是经卷绕后得到电极组件；将电极组件置于包装外壳中，注入电解液并封口，得到电化学装置。
本申请的电化学装置可以包括发生电化学反应的任何装置，它的具体实例包括所有种类的一次电池或二次电池。特别地，该电化学装置是锂二次电池，包括锂金属二次电池、锂离子二次电池、锂聚合物二次电池或锂离子聚合物二次电池。
电子设备
本申请的电子设备包括本申请的上述任意一种电化学装置。本申请的电子设备置可用于，但不限于，笔记本电脑、笔输入型计算机、移动电脑、电子书播放器、便携式电话、便携式传真机、便携式复印机、便携式打印机、头戴式立体声耳机、录像机、液晶电视、手提式清洁器、便携CD机、迷你光盘、收发机、电子记事本、计算器、存储卡、便携式录音机、收音机、备用电源、电机、汽车、摩托车、助力自行车、自行车、照明器具、玩具、游戏机、钟表、电动工具、闪光灯、照相机、家庭用大型蓄电池和锂离子电容器等。
以下，举出实施例及对比例来对本申请的实施方式进行更具体地说明。除非另有声明，以下所列的份、百分比和比值都是基于重量计，所使用的原料都可商购获得或是按照常规方法进行合成获得。
实施例1
正极极片的制备
将第一材料LiFePO 4、第二材料Li 1.2Ni 0.133Fe 0.133Mn 0.534O 2、粘结剂(PVDF)、导电炭黑进行混合，其中LiFePO 4、Li 1.2Ni 0.133Fe 0.133Mn 0.534O 2、PVDF和导电炭黑的重量比为88.5：8.0：1.5：2.0，加入溶剂NMP，在真空搅拌机作用下混合均匀，获得正极浆料；将正极浆料均匀涂覆在正极集流体铝箔的一侧表面上，烘干，得到单面涂覆的正极极片，再在铝箔的另一侧表面重复上述步骤，即得到双面涂覆的正极极片，再经过冷压，分切，得到正极极片。
负极极片的制备
将负极活性材料人造石墨、羧甲基纤维素钠(CMC)、丁苯橡胶(SBR)及导电炭黑按照质量比95.7：1.0：1.8：1.5进行混合，加入去离子水，在真空搅拌机作用下混合均匀，获得负极浆料；将负极浆料均匀涂覆在负极集流体铜箔的一侧表面上，烘干，得到单面涂覆的负极极片，再在铜箔的另一侧表面重复上述步骤，即得到双面涂覆的负极极片，再经过冷压，分切，得到负极极片。
电解液的制备
将碳酸乙烯酯(EC)、碳酸甲乙酯(EMC)及碳酸二乙酯(DEC)按照体积比为1:1:1混合均匀，得到有机溶剂。将LiPF 6溶解于上述有机溶剂中，再加入碳酸亚乙烯酯，混合均匀，得到电解液。其中，基于电解液的总质量，LiPF 6的质量百分含量为12.5％、碳酸亚乙烯酯的质量百分含量为3％。
锂离子电池的制备
将正极极片、隔离膜、负极极片依次层叠设置，隔离膜采用厚度为14μm的聚丙烯(PP)多孔膜，其处于正极极片和负极极片之间起到隔离作用，然后卷绕成裸电芯，将裸电芯装入铝塑膜中，注入电解液并封口，之后经过静置、化成、整形等工序，得到锂离子电池。其中，化成工序如下：在45℃下，进行首圈充放电，流程如下：首先以0.1C倍率恒流充电10min，随后以0.5C倍率恒流充电至指定电压Q＝4.6V，再恒压充电至电流小于等于0.05C，接着以0.5C倍率恒流放电至2.5V。
实施例2～25
与实施例1不同的是，调整正极极片中的材料组分和制备步骤中的相关参数，详见表1。
对比例1～5
与实施例1不同的是，调整正极极片中的材料组分和制备步骤中的相关参数，详见表1。
测试方法
(1)X射线衍射测试：
将锂离子电池满充后拆解，获得正极极片，采用X射线衍射测试仪(荷兰帕纳科，XPertPro MPD)，并设定测试条件：Cu K α辐射
Figure PCTCN2022094735-appb-000001
工作电流250mA，采用连续扫描，工作电压为40kV，扫描范围2θ为10°～70°，步长0.1°，扫描速度0.2秒/步。
(2)SEM测试：
采用卡尔蔡司ZEISS SIGMA-500型场发射扫描电子显微镜对样品进行形貌观察和平均粒径的测试。在合适的倍率下拍摄SEM照片，使用图像处理软件，随机统计50个第一材料颗粒的最长直径，取其平均值作为第一材料的平均粒径 D 1；随机统计50个第二材料颗粒的最长直径，取其平均值作为第二材料的平均粒径D 2。
(3)高温循环性能测试
在60℃下，将锂离子电池以1C倍率恒流充电至4.0V，再4.0V恒压充电至电流为0.05C，再以1C倍率恒流放电至2.5V，此为一个充放电循环，记录锂离子电池第一次循环的放电容量。将锂离子电池按照上述方法进行充放电循环，记录每一次循环的放电容量，直至锂离子电池的放电容量衰减至第一次循环的放电容量的80％，记录充放电循环次数。
(4)倍率性能测试
在25℃下，将锂离子电池以0.5C倍率恒流充电至4.0V，再4.0V恒压充电至电流为0.05C，再以0.5C倍率恒流放电至2.5V，记录0.5C倍率的放电容量。
在25℃下，将锂离子电池以0.5C倍率恒流充电至4.0V，再4.0V恒压充电至电流为0.05C，再以2C倍率恒流放电至2.5V，记录2C倍率的放电容量。
锂离子电池2C倍率放电容量保持率(％)＝2C倍率放电容量/0.5C倍率放电容量×100％。
实施例1～25以及对比例1～5的测试结果见表2。
表1
Figure PCTCN2022094735-appb-000002
Figure PCTCN2022094735-appb-000003
Figure PCTCN2022094735-appb-000004
表2
Figure PCTCN2022094735-appb-000005
Figure PCTCN2022094735-appb-000006
从表1的参数特征和表2的测试数据以及结合图1和图2可以看出，本申请通过将具有橄榄石型晶体结构的第一材料和富锂的具有层状晶体结构的第二材料在正极极片中共同使用，并巧妙设计正极极片的组成以及化成时的截止电压，使锂离子电池满充后，正极极片的XRD衍射谱中，第二材料(003)晶面的衍射峰A1的峰强度I A1与第一材料(311)晶面的衍射峰C1的峰强度I C1之间的峰强比满足：3≤I C1/I A1≤100，能够使所述正极极片在循环过程中具有较高的结构稳定性，从而使得锂离子电池具有显著改善的高温循环寿命。
从实施例1～24与实施例25的比较可以看出，在所述第二材料组分中加入适量的T元素(Fe和/或Co)，0.05≤n T/n M≤0.5时，可进一步提升锂离子电池的高温循环寿命，这是由于，在所述第二材料组分中加入适量的T元素，使得所述第二材料在脱锂后的结构更稳定，第二材料脱锂后产物中Mn元素的形态多为Mn 4+，因此可以有效抑制Mn 3+的姜-泰勒畸变效应，降低了Mn元素的溶出对SEI膜的破坏，从而有效提升电化学装置的高温循环寿命。进一步地，从实施例1与实施例6的比较可以看出，包含Fe的第二材料相比于包含Co的第二材料，能够进一步改善锂离子电池的高温循环寿命。这是由于，Fe 3+到Fe 4+的离子化能远高于Co 3+到Co 4+的离子化能，因此，在高电压下循环时，Fe的平均价态比Co的平均价态低，一方面可降低高价金属离子在界面上对电解液的氧化，另一方面有利于Mn维持高价态，抑制Mn的姜-泰勒畸变效应，降低Mn溶出风险，同时，能够增强材料的结构稳定性，抑制过渡金属向锂层的迁移，从而提升锂离子电池的高温循环寿命。
此外，实施例22和实施例23中虽然也均含有所述第一材料和所述第二材料，且其XRD衍射谱中C1峰和A1峰的峰强比I C1/I A1也在合适的范围内，但由于其所使用的第二材料的(003)晶面的衍射峰A1和(104)晶面的衍射峰B1的 峰强比I A1/I B1均不在1～5的范围内，锂离子电池的高温循环性能和倍率性能均较低，这是由于，峰强比I A1/I B1可反映具有层状晶体结构的锂锰复合氧化物中阳离子的混排程度和层状晶体结构的稳定性，一方面，I A1/I B1过小，第二材料中阳离子混排程度大，结构不稳定，导致高温循环性能和倍率性能降低；另一方面，I A1/I B1过大，第二材料的层状晶体结构稳定性过高，不利于首圈化成时的活化以及后续循环过程中锂离子的脱出，进而导致锂离子电池的高温循环性能和倍率性能降低。
以上所述仅为本申请的较佳实施例而已，并不用以限制本申请，凡在本申请的精神和原则之内所作的任何修改、等同替换和改进等，均应包含在本申请的保护范围之内。

Claims (10)

  1. 一种电化学装置，包括正极极片，所述正极极片包括正极活性材料层，所述正极活性材料层包括第一材料和第二材料；所述电化学装置在满充状态下，所述正极极片的XRD衍射图谱中，在18°至20°范围内存在所述第二材料(003)晶面的衍射峰A1，在35°至37°范围内存在所述第一材料(311)晶面的衍射峰C1。
  2. 根据权利要求1所述的电化学装置，其特征在于，所述衍射峰A1的峰强度为I A1，所述衍射峰C1的峰强度为I C1，满足：3≤I C1/I A1≤100。
  3. 根据权利要求1所述的电化学装置，其特征在于，所述正极极片的XRD衍射图谱中，在44°至46°范围内存在所述第二材料(104)晶面的衍射峰B1，所述衍射峰B1的峰强度为I B1，满足：1≤I A1/I B1≤5。
  4. 根据权利要求2所述的电化学装置，其特征在于，3≤I C1/I A1≤55。
  5. 根据权利要求1所述的电化学装置，其特征在于，满足以下条件中的至少一者：
    (i)所述第一材料为具有橄榄石型晶体结构的锂过渡金属磷酸化合物；所述第二材料为具有层状晶体结构的锂锰复合氧化物；
    (ii)所述第二材料包括R-3m和C2/m晶相结构；
    (iii)所述第二材料包括Mn元素、T元素、O元素、可选的Ni元素以及可选的T′元素，所述T元素包括Fe或Co中的至少一种；所述T′元素包括Mg、Al、Ti、V、Cr、Cu、Y、Zr、Nb、Mo、La、Zn、Ga、Ru、Ag、Sn、Au、Ce、 Pr、Nd、Sm、Gd或W中的至少一种；所述第二材料中，所述Mn元素的摩尔量为n Mn，所述T元素的摩尔量为n T，所述O元素的摩尔量为n O，所述Ni元素的摩尔量为n Ni，所述T′元素的摩尔量为n T′，所述Mn元素、T元素、Ni元素和T′元素的摩尔量之和为n M，满足：0.25≤n Mn/n M≤0.85，0.05≤n T/n M≤0.65，0≤n Ni/n M≤0.4，0≤n T′/n M≤0.05，0.35≤n M/n O≤0.475；
    (iv)所述第一材料包括Fe元素、可选的Mn元素以及可选的T″元素，所述T″元素包括Ti、Zr、V、Al、Co、Ni、Cu、Zn、Mg、Ga、Nb或Cr中的至少一种，所述第二材料中，所述Fe元素的摩尔量为m Fe，所述Mn元素的摩尔量为m Mn，所述T″元素的摩尔量为m T″，所述Fe元素、Mn元素和T″元素的摩尔量之和为m M，满足：0.5≤m Fe/m M≤1，0≤m Mn/m M≤0.5，0≤m T″/m M≤0.2。
  6. 根据权利要求5所述的电化学装置，其特征在于，满足以下条件中的至少一者：
    (a)0.05≤n T/n M≤0.5；
    (b)所述T元素包括Fe，所述第二材料中，Fe元素的摩尔量为n Fe，满足：0.05≤n Fe/n M≤0.5。
  7. 根据权利要求1所述的电化学装置，其特征在于，满足以下条件中的至少一者：
    (1)所述第一材料的平均粒径为D 1，所述第二材料的平均粒径为D 2，满足：3≤D 2/D 1≤10；
    (2)所述第一材料的平均粒径D 1为0.5μm至3μm；
    (3)所述第二材料的平均粒径D 2为4μm至9μm。
  8. 根据权利要求1所述的电化学装置，其特征在于，所述正极活性材料层的压实密度为P，满足：1.8g/cm 3≤P≤2.7g/cm 3。
  9. 根据权利要求1所述的电化学装置，其特征在于，满足以下条件中的至少一者：
    (1)所述第二材料包括具有化学式Ⅰ所示材料中的任一种：
    Li 2-eNi aT bMn cT′ dO 2  化学式Ⅰ
    其中，0≤a≤0.35，0<b≤0.6，0.25≤c≤0.6，0≤d≤0.05，0.7≤a+b+c+d≤0.95，0.7≤e≤0.95；T包括Fe或Co中的至少一种；T′包括Mg、Al、Ti、V、Cr、Cu、Y、Zr、Nb、Mo、La、Zn、Ga、Ru、Ag、Sn、Au、Ce、Pr、Nd、Sm、Gd或W中的至少一种；
    (2)所述第一材料包括具有化学式Ⅱ所示材料中的任一种；
    Li xFe yMn zT″ 1-y-zPO 4-tA t  化学式Ⅱ
    其中，0.6≤x≤1.2，0.5≤y≤1，0≤z≤0.5，0.8≤y+z≤1，0≤t≤0.2，T″包括Ti、Zr、V、Al、Co、Ni、Cu、Zn、Mg、Ga、Nb或Cr中的至少一种，A包括S、N、F、Cl或Br中的至少一种。
  10. 一种电子设备，包括权利要求1-9中任一项所述的电化学装置。
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CN109713229A (zh) * 2019-01-18 2019-05-03 北京中能东道绿驰科技有限公司 一种正极极片的制备方法及包含其的锂离子电池
CN113937255A (zh) * 2020-06-29 2022-01-14 北京卫蓝新能源科技有限公司 一种锂离子电池复合正极材料及其制备方法和应用

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