WO2023245534A1 - 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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WO2023245534A1
WO2023245534A1 PCT/CN2022/100662 CN2022100662W WO2023245534A1 WO 2023245534 A1 WO2023245534 A1 WO 2023245534A1 CN 2022100662 W CN2022100662 W CN 2022100662W WO 2023245534 A1 WO2023245534 A1 WO 2023245534A1
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hard carbon
value
negative electrode
electrochemical device
lithium
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PCT/CN2022/100662
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English (en)
French (fr)
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易政
郑子桂
谢远森
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宁德新能源科技有限公司
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Priority to PCT/CN2022/100662 priority Critical patent/WO2023245534A1/zh
Priority to CN202280054231.3A priority patent/CN117859216A/zh
Publication of WO2023245534A1 publication Critical patent/WO2023245534A1/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
    • 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
    • H01M4/133—Electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • 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
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • H01M4/587—Carbonaceous material, e.g. graphite-intercalation compounds or CFx for inserting or intercalating light metals

Definitions

  • the present application relates to the technical field of lithium batteries, and in particular to an electrochemical device and electronic equipment.
  • Lithium-ion batteries have the advantages of large volume and mass energy density, environmental friendliness, high operating voltage, small size, light weight, and long cycle life. They are widely used in the field of portable consumer electronics. With the rapid development of electric vehicles and mobile electronic devices in recent years, people have higher and higher demands for battery energy density, safety, cycle performance and other related requirements, and are looking forward to the emergence of new lithium-ion batteries with comprehensively improved comprehensive performance; among them , energy density and cycle performance have become key technical issues that need to be solved urgently. Improving active materials in electrodes is one of the research directions to solve the above problems.
  • Graphite is currently the most widely used anode material. It has the advantages of small polarization and stable charge and discharge platform. However, the performance of current commercial graphite has been developed almost to the extreme. It has high reversible gram capacity and energy density without lithium precipitation. It is difficult to achieve further improvement. Therefore, developing new alternative anode materials is one of the research directions to solve the current low energy density of lithium-ion batteries.
  • Embodiments of the present application provide an electrochemical device and electronic equipment that use hard carbon as an active material.
  • By regulating the H/C value of the hard carbon and the CB value of the electrochemical device it is possible to increase the energy density without lithium precipitation. , that is, both improving lithium evolution and increasing energy density.
  • an electrochemical device including a negative electrode piece.
  • the negative electrode piece includes a negative active material layer.
  • the negative active material in the negative active material layer includes hard carbon.
  • the hard carbon The H/C value ranges from 0.05 to 0.18, and the CB value of the electrochemical device ranges from 0.95 to 1.05; where the H/C value is the molar ratio of the H element to the C element in the hard carbon, and the CB value is the negative electrode capacity per unit area.
  • the ratio to the positive electrode capacity per unit area By controlling the molar ratio of H element to C element in the hard carbon between 0.05 and 0.18, the molar ratio of H element and C element in the negative active material layer is controlled between 0.1 and 0.5.
  • the H element in the negative active material layer The molar ratio to the C element is within a suitable range, which is beneficial to improving the transmission speed of active ions.
  • the CB value of the electrochemical device is controlled to be 0.95 to 1.05. The combination of the two is beneficial to improving the energy density of the electrochemical device, and Improve the lithium evolution of electrochemical devices.
  • the negative electrode piece in the fully charged state (i.e. 100% charge state) has a thermal weight loss peak in the range of 150°C to 220°C, and the peak area is >100J/g; wherein, the thermal weight loss peak is The weight loss peak is the thermal weight loss peak of metalloid lithium in the hard carbon micropores.
  • the size of its peak area is consistent with the energy density trend of the electrochemical device. That is, the larger the peak area, the more metalloid lithium is stored in the same area of the pole piece.
  • the peak area of the thermal weight loss peak is used to characterize the lithium storage characteristics of hard carbon; in the XRD diffraction pattern of the negative electrode plate, the 2 times scattering angle is between 20° and 30° There is a diffraction peak A1 in the range, and its half-peak width is between 3° and 10°.
  • the diffraction peak A1 is a characteristic peak of hard carbon; in the Raman spectrum of the negative electrode plate, it is in the range of 1320cm -1 to 1370cm -1 In the characteristic peak D1, its peak intensity is I D1 .
  • D1 is a disordered peak, which reflects the degree of disorder inside the carbon material.
  • G1 there is a characteristic peak G1 in the range of 1570cm -1 to 1620cm -1 , and its peak intensity is I G1 , G1 is the graphitization peak, reflecting the in-plane stretching vibration of sp 2 hybridization of C atoms, and satisfies 0.5 ⁇ I D1 /I G1 ⁇ 1.5; by controlling the peak intensity ratio of I D1 and I G1 between 0.5 and 1.5, This allows the lithium ions to have a higher transmission speed and the electrochemical device to have a higher energy density; if the peak intensity ratio I D1 /I G1 is less than 0.5, it means that the degree of disorder is low and the hard carbon material has fewer lithium storage sites.
  • the specific surface area BET of the hard carbon is 1.5m 2 /g to 10m 2 /g. If the BET value is too large (for example, greater than 10m 2 /g), it is not conducive to the processing of anode plates in the preparation process of lithium ion batteries. , such as the pulping and coating process.
  • the compaction density P of the negative electrode piece By controlling the compaction density P of the negative electrode piece under a pressure of 5t in an appropriate range, it is beneficial to increase the energy density of the electrochemical device, and at the same time, the ratio of the BET value of the hard carbon to the compaction density P of the negative electrode piece is controlled to be greater than 1.7, to further improve the energy density and dynamic performance of electrochemical devices.
  • the particle size value Dv50 of the particles at 50% of the cumulative volume distribution curve of the hard carbon ranges from 2 ⁇ m to 15 ⁇ m, and the particle size value Dv99 of the particles at 99% of the cumulative volume distribution curve.
  • the range is 8 ⁇ m to 45 ⁇ m, and its gram capacity at 0V to 2.0V is 300mAh/g to 1200mAh/g; by controlling the particle size range of the hard carbon, if the particle size of the hard carbon is too small, it will cause its BET If the value is too large, on the one hand, it is not conducive to the processing of the anode plates during the preparation of lithium-ion batteries.
  • the first Coulombic efficiency of the prepared electrochemical device will also cause the first Coulombic efficiency of the prepared electrochemical device to be low, thus affecting the energy density; and if the hard carbon particles If the diameter is too large, it is not conducive to improving the kinetic performance of the electrochemical device; it can be seen that a suitable particle size distribution is conducive to improving the kinetic performance of the electrochemical device, thereby increasing the energy density.
  • the preparation process of the hard carbon includes the following steps: sequentially subjecting the carbon source to precursor modification treatment, first calcination treatment, classification treatment and second calcination treatment;
  • Precursor modification treatment When the carbon source is biomass corn starch, it is usually placed in an air atmosphere and oxidized at 150°C to 200°C for 5h to 20h; when the carbon source is biomass coconut shell, it is usually Soak it in an alkaline solution and heat it with water at 150°C to 200°C for 5h to 20h; when the carbon source is phenolic resin, the treatment method is the same as biomass corn starch; when the carbon source is asphalt, it needs to be Soak it in an organic solution for 5h to 10h, and then oxidize it at different temperatures for 5h to 20h to complete the precursor modification process of the carbon source; the purpose of the precursor modification process is to fix the precursor modification process.
  • the pore characteristics of the sexual process are expected to be retained in the subsequent carbonization process;
  • the first calcination treatment the product after the precursor modification is placed in an inert atmosphere and calcined at 500°C to 600°C for 2h to 3h.
  • Preliminary carbonization precursor fixing the basic structure of the carbon material;
  • classification treatment crushing and classifying the product after the first calcination treatment to screen out the required particle size;
  • second calcination treatment classifying the product The product is placed under an inert atmosphere and kept at ultra-high temperature for 2 to 3 hours to eliminate and reduce functional groups in the carbon material, shrink the surface structure, reduce the specific surface area, and reduce irreversible components.
  • the temperature of the second calcination treatment is usually not higher than 1000°C.
  • the temperature of the second calcination treatment is higher than 1000°C
  • after the second calcination treatment Surface modification coating treatment and third calcining treatment; Surface modification coating is performed by placing the product after the second calcining treatment in 10% CH 4 /Ar mixed gas for CVD coating.
  • the surface modification coating The sexual coating is carried out simultaneously with the third calcining treatment, that is, the product after the second calcining treatment is placed in a 10% CH 4 /Ar mixed gas at a temperature lower than 1000°C (the third calcining treatment).
  • the pyrolysis temperature of the coating layer formed through the surface modification coating treatment is 700°C to 1000°C.
  • the surface of carbon is covered with a coating layer to eliminate and reduce irreversible functional groups and open pore components in the carbon material.
  • the pyrolysis temperature of the coating layer is controlled to 700°C to 1000°C to allow methane to deposit and retain a certain amount of The H/C value ratio finally obtains hard carbon with an H/C value of 0.05 to 0.18.
  • embodiments of the present application provide an electronic device, including any of the above electrochemical devices.
  • the invention provides an electrochemical device, including a negative electrode piece, the negative electrode piece includes a negative active material layer, the negative active material in the negative active material layer includes hard carbon, and the H/C value of the hard carbon is 0.05 to 0.18, and the CB value of the electrochemical device is 0.95 to 1.05.
  • the molar ratio of H element to C element in the hard carbon between 0.05 and 0.18
  • the molar ratio of H element and C element in the negative active material layer is controlled between 0.1 and 0.5.
  • the H element in the negative active material layer The molar ratio to the C element is within a suitable range, which is beneficial to increasing the transmission speed of active ions.
  • regulating the CB value of the electrochemical device to 0.95 to 1.05 is beneficial to increasing the energy density of the electrochemical device and improving the performance of the electrochemical device. Lithium precipitation situation.
  • Figure 1 is the thermal analysis spectrum of the negative electrode piece in Example 2 of the present application.
  • Figure 2 is a particle size distribution diagram of hard carbon particles in Example 2 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.
  • Hard carbon is one of the potential anode materials that can replace graphite. Its reversible gram capacity can be 1 to 2 times that of graphite anode. Therefore, when using hard carbon as a substitute for graphite as an anode material for lithium-ion batteries, , the energy density of the entire lithium-ion battery is expected to be improved to a certain extent. At the same time, hard carbon has different physical and chemical properties from graphite. For example, hard carbon has richer pores, which makes it less susceptible to lithium precipitation than graphite when used as an anode material for lithium ion batteries.
  • hard carbon As a new anode material, hard carbon has Richer pore structure, and relative lithium potential ⁇ 0V, so compared to graphite, hard carbon with low CB value is less likely to precipitate lithium; if the hard carbon is designed according to the graphite system, the energy of the electrochemical device obtained The density ED is low. Therefore, studying hard carbon systems with different H/C values and CB values will help increase the energy density of electrochemical devices and improve the lithium evolution of electrochemical devices.
  • this application proposes an electrochemical device, including a negative electrode piece, a separator, a positive electrode piece and an electrolyte.
  • the negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer disposed on at least one surface of the negative electrode current collector; the negative electrode active material in the negative electrode active material layer includes hard carbon, and the H/C value of the hard carbon
  • the value range is 0.05 to 0.18, and the selection range of the CB value of the electrochemical device is 0.95 to 1.05; wherein, the H/C value is the molar ratio of the H element to the C element in the hard carbon, and the CB value is the negative electrode per unit area. The ratio of capacity to positive electrode capacity per unit area.
  • the H/C value of the hard carbon is a range consisting of 0.05, 0.08, 0.10, 0.12, 0.14, 0.16, 0.18 or any two of the above values.
  • the CB value of the electrochemical device is a range consisting of 0.95, 0.97, 0.99, 1.01, 1.03, 1.05 or any two of the above values.
  • the hard carbon has an H/C value of 0.05 to 0.15.
  • the H/C value of the hard carbon is a range consisting of 0.05, 0.06, 0.07, 0.09, 0.11, 0.13, 0.15 or any two of the above values.
  • the H/C value of the hard carbon is 0.08 to 0.15.
  • the H/C value of the hard carbon is a range consisting of 0.08, 0.10, 0.11, 0.13, 0.15 or any two of the above values.
  • the electrochemical device has a CB value of 0.96 to 1.00.
  • the CB value of the electrochemical device is a range consisting of 0.96, 0.97, 0.98, 0.99, 1.00 or any two of the above values.
  • the CB value of the electrochemical device is 0.98 to 1.00.
  • the CB value of the electrochemical device is a range consisting of 0.98, 0.99, 1.00 or any two of the above values.
  • the electrochemical device satisfies at least one of the following conditions:
  • the negative electrode piece in the fully charged state has a thermal weight loss peak in the range of 150°C to 220°C, and the peak area is >100J/g; preferably, the peak area is >110J/g .
  • the half-peak width of the diffraction peak A1 is a range consisting of 3°, 5°, 8°, 10° or any two of the above values.
  • the peak intensity ratio I D1 /I G1 of the characteristic peak D1 and the characteristic peak G1 is a range consisting of 0.5, 0.8, 1.0, 1.2, 1.5 or any two of the above values.
  • the electrochemical device satisfies at least one of the following conditions:
  • the specific surface area BET of the hard carbon is 1.5m 2 /g to 10m 2 /g;
  • the specific surface area BET of the hard carbon is 1.5m 2 /g, 2m 2 /g, 4m 2 /g, 6m 2 /g, 8m 2 /g, 10m 2 /g or any two of the above values. range.
  • the compacted density P of the negative electrode sheet tested under 5t pressure is 0.85g/cm 3 , 0.88g/cm 3 , 0.98g/cm 3 , 1.1g/cm 3 or any two of the above values. scope.
  • the electrochemical device satisfies at least one of the following conditions:
  • the hard carbon has a specific surface area BET of 2m 2 /g to 8m 2 /g;
  • the specific surface area BET of the hard carbon is 2m 2 /g, 3m 2 /g, 5m 2 /g, 6m 2 /g, 8m 2 /g or a range consisting of any two of the above values.
  • the compacted density P of the negative electrode sheet tested under 5t pressure is 0.98g/cm 3 , 1.0g/cm 3 , 1.01g/cm 3 , 1.03g/cm 3 , 1.05g/cm 3 or A range consisting of any two values above.
  • the ratio M of the specific surface area BET of the hard carbon to the compacted density P of the negative electrode piece is 2, 3, 5, 7, 9 or a range consisting of any two of the above values.
  • the volume v of the negative active material layer may be the product of the area S of the negative active material layer and the thickness h of the negative active material layer.
  • the specific surface area of the negative electrode material can be measured by the BET test method (Brunauer-Emmett-Teller, BET); first use the Tri Star II specific surface analyzer, use a sample tube to fill 3g-6g of the sample, and then put the sample into the degassing In the station, the sample is heated and evacuated, and then the heating and vacuum are turned off to reduce the sample temperature to room temperature. The sample and sample tube are unloaded and measured, and then loaded into the analysis station for analysis, and data processing and calculations are performed.
  • BET test method Brunauer-Emmett-Teller, BET
  • the electrochemical device satisfies at least one of the following conditions:
  • the particle size value Dv50 of the hard carbon particles at 50% of the cumulative volume distribution curve ranges from 2 ⁇ m to 15 ⁇ m;
  • the particle size value Dv50 of the hard carbon particles at 50% of the cumulative volume distribution curve is 2 ⁇ m, 4 ⁇ m, 6 ⁇ m, 8 ⁇ m, 10 ⁇ m, 12 ⁇ m, 15 ⁇ m, or a range consisting of any two of the above values.
  • the particle diameter value Dv99 of the hard carbon particles at 99% of the cumulative volume distribution curve is 8 ⁇ m, 10 ⁇ m, 20 ⁇ m, 30 ⁇ m, 40 ⁇ m, 45 ⁇ m, or a range consisting of any two of the above values.
  • the electrochemical device satisfies at least one of the following conditions:
  • the particle diameter value Dv50 of the hard carbon particles at 50% of the cumulative volume distribution curve is 5 ⁇ m, 5.5 ⁇ m, 6 ⁇ m, 6.5 ⁇ m, 7 ⁇ m, or a range consisting of any two of the above values.
  • the particle size value Dv99 of the hard carbon particles at 99% of the cumulative volume distribution curve is 25 ⁇ m, 30 ⁇ m, 35 ⁇ m, 40 ⁇ m, or a range consisting of any two of the above values.
  • This application also discloses a preparation process of the hard carbon, which includes the following steps:
  • the carbon source is sequentially subjected to precursor modification treatment, first calcination treatment, classification treatment, and second calcination treatment.
  • the precursor modification treatment when the carbon source is biomass corn starch, it is usually placed in an air atmosphere and oxidized at 150°C to 180°C for 5h to 10h; when the carbon source is biomass coconut shell, It is usually soaked in sodium hydroxide solution and heated with water at 150°C to 180°C for 5h to 10h; when the carbon source is phenolic resin, the treatment method is the same as biomass corn starch; when the carbon source is asphalt When needed, it needs to be soaked in quinoline solution for 5h to 8h, and then oxidized at 150°C, 200°C, 250°C, and 300°C for 5h to 10h to complete the precursor modification of the carbon source. deal with;
  • the first calcination treatment place the product modified by the precursor in an argon or nitrogen atmosphere and calcine it at 500°C to 550°C for 2 hours;
  • the second calcining treatment place the graded product in an argon atmosphere and calcine at 700°C to 1000°C for 2 hours; when the temperature of the second calcining treatment is higher than 1000°C, After the secondary calcination treatment, it also includes: surface modification coating treatment and a third calcination treatment; the temperature of the third calcination treatment is 700°C to 900°C.
  • the pyrolysis temperature of the coating layer formed by the surface modification coating treatment is 700°C to 1000°C.
  • the pyrolysis temperature of the coating layer is a range consisting of 700°C, 800°C, 900°C, 1000°C or any two of the above values.
  • the third calcination temperature is a range consisting of 850°C, 900°C, 920°C, 950°C or any two of the above values.
  • step (3) The negative electrode current collector coated with the negative electrode active material layer in step (2) is dried, cold pressed, and cut to obtain a negative electrode piece.
  • the positive electrode sheet includes a positive current collector and a positive active material layer disposed on at least one surface of the positive current collector.
  • the positive active material in the positive active material layer can be selected from the group consisting of lithium cobalt oxide, lithium nickel oxide, and lithium manganese oxide.
  • the positive electrode current collector may use a metal foil or a porous metal plate, such as a foil or a porous plate made of metals such as aluminum, copper, nickel, titanium, iron, or their alloys, such as Al (aluminum) foil.
  • a metal foil or a porous metal plate such as a foil or a porous plate made of metals such as aluminum, copper, nickel, titanium, iron, or their alloys, such as Al (aluminum) foil.
  • the positive electrode sheet can be prepared according to conventional methods in the art.
  • the isolation film may be a polyethylene film, a polypropylene film, a polyvinylidene fluoride film and a multi-layer composite film thereof, but is not limited to these materials.
  • 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 sulfonate cyclic quaternary ammonium salt, tris(trimethylsilane)phosphate (TMSP) or tris(trimethylsilane)borate (TMSB).
  • the above electrolyte solution can be prepared according to conventional methods in the art.
  • 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.
  • Hard carbon (H/C value between 0.05 and 0.18) powder is made from resin, biomass materials such as coconut shell or asphalt, and is completed through processes such as precursor modification, first calcination, classification, and second calcination.
  • Biomass corn starch is used as raw material, oxidized at 180°C for 5 hours in an air atmosphere (precursor modification), and then calcined in a tube furnace at 500°C for 2 hours in an argon atmosphere (first calcination). After cooling, it is crushed and classified (large particles below 400 mesh are removed), and then calcined for the second time. The temperature is raised to 1000°C in an argon atmosphere and kept for 2 hours. After cooling, the final product is obtained, recorded as hard carbon 1;
  • Synthesis of hard carbon 2 After crushing the biomass coconut shell to less than 1mm, wash it with clean water, put it into a reactor, soak it in 1M sodium hydroxide solution and hydroheat at 180°C for 5 hours (precursor modification), take it out Then dry and calcine in a tube furnace at 500°C for 2 hours in an argon atmosphere. After cooling, crush and classify (remove large particles below 400 mesh), wash with deionized water until neutral, then dry and calcine for the second time. The temperature is raised to 1100°C in an argon atmosphere, kept for 2 hours, and then cooled down; then CVD coating is performed at 900°C.
  • the coating atmosphere is a 10% CH 4 /Ar mixed gas (that is, the content of CH 4 in the mixed gas is 10wt%).
  • the time is 1 hour (surface modification coating and third calcination), and the obtained product is recorded as hard carbon 2, in which the pyrolysis temperature of the formed coating layer is 750°C;
  • hard carbon 3 The synthesis of hard carbon 3 is similar to that of hard carbon 2, except that the second calcination temperature is changed to 850°C; CVD coating and third calcination treatment are not performed, and the obtained product is recorded as hard carbon 3;
  • hard carbon 4 The synthesis of hard carbon 4 is similar to that of hard carbon 2, except that the second calcination temperature is changed to 700°C; CVD coating and third calcination treatment are not performed, and the obtained product is recorded as hard carbon 4;
  • Synthesis of hard carbon 5 Use phenolic resin as raw material, oxidize it at 180°C for 5 hours in an air atmosphere, and then calcine it in a tube furnace at 500°C for 2 hours in an argon atmosphere. After cooling, crush and classify (remove large particles below 400 mesh). Then perform the second calcination, raise the temperature to 1200°C in an argon atmosphere, keep it for 2 hours, and then lower the temperature; then conduct CVD coating at 900°C, the coating atmosphere is 10% CH 4 /Ar mixed gas (that is, CH 4 accounts for the mixture The gas content is 10wt%), the time is 1h, the product obtained is recorded as hard carbon 5, and the pyrolysis temperature of the coating layer formed is 750°C;
  • hard carbon 6 The synthesis of hard carbon 6 is similar to that of hard carbon 5, except that the second calcination temperature is changed to 900°C; CVD coating and third calcination treatment are not performed, and the obtained product is recorded as hard carbon 6;
  • hard carbon 7 The synthesis of hard carbon 7 is similar to that of hard carbon 5, except that the second calcination temperature is changed to 700°C; CVD coating and third calcination treatment are not performed, and the obtained product is recorded as hard carbon 7;
  • Synthesis of hard carbon 8 Using petroleum asphalt as raw material, soak the asphalt particles with a Dv50 of 15um in quinoline for 5 hours, filter and dry them, and then heat them at 150°C, 200°C, 250°C, and 300°C in a flowing air atmosphere. Each step was oxidized for 5 hours (precursor modification), and then calcined in a tube furnace at 500°C for 2 hours in an argon atmosphere. After cooling, it was crushed and classified (large particles below 400 mesh were removed), and then calcined for the second time in argon.
  • the temperature is raised to 1100°C in an air atmosphere, kept for 2 hours, and then cooled down; then CVD coating is performed at 900°C, the coating atmosphere is 10% CH 4 /Ar mixed gas (that is, the content of CH 4 in the mixed gas is 10wt%), time is 1h, and the product obtained is recorded as hard carbon 8;
  • hard carbon 9 The synthesis of hard carbon 9 is similar to that of hard carbon 8, except that the second calcination temperature is changed to 900°C; CVD coating and third calcination treatment are not performed, and the obtained product is recorded as hard carbon 9;
  • hard carbon 10 The synthesis of hard carbon 10 is similar to that of hard carbon 8, except that the second calcination temperature is changed to 700°C; CVD coating and third calcination treatment are not performed, and the obtained product is recorded as hard carbon 10;
  • Synthesis of hard carbon 11 After crushing the biomass coconut shell to less than 1mm, wash it with clean water, put it into a reaction kettle, soak it in 1M sodium hydroxide solution and hydroheat at 180°C for 5 hours (precursor modification). After taking it out, it is dried and calcined in a tube furnace at 500°C for 2 hours in an argon atmosphere. After cooling, it is crushed and classified (to remove large particles below 400 mesh), and washed with deionized water until neutral, then dried and calcined for the second time. Raise the temperature to 1200°C in an argon atmosphere, keep it warm for 2 hours, and then cool down;
  • Synthesis of hard carbon 12 The synthesis of hard carbon 12 is similar to that of hard carbon 2, except that the second calcination temperature is changed to 600°C; CVD coating and third calcination treatment are not performed, and the obtained product is recorded as hard carbon 12;
  • Synthesis of hard carbon 13 After crushing the biomass coconut shell to less than 1mm, wash it with clean water, put it into a reactor, soak it in 1M sodium hydroxide solution and hydroheat at 180°C for 5 hours (precursor modification). After taking it out, it is dried and calcined in a tube furnace at 500°C for 2 hours in an argon atmosphere. After cooling, it is crushed and classified (to remove large particles below 400 mesh), and washed with deionized water until neutral, then dried and calcined for the second time. Raise the temperature to 1000°C in an argon atmosphere, keep it warm for 2 hours, and then cool down;
  • Graphite is commercially available artificial graphite
  • Biomass corn starch, biomass coconut shell, phenolic resin and petroleum asphalt are all purchased through commercial channels.
  • the manufacturer of biomass corn starch is Aladdin Reagent
  • the manufacturer of petroleum asphalt is Liaoning Hongyu Carbon Graphite Materials Co., Ltd. .
  • the hard carbon material prepared above was used as the negative active material, and was thoroughly stirred and mixed with styrene-butadiene rubber (SBR) and sodium carboxymethylcellulose (CMC) in an appropriate amount of deionized water at a weight ratio of 97:2:1.
  • SBR styrene-butadiene rubber
  • CMC sodium carboxymethylcellulose
  • a uniform negative electrode slurry is formed, wherein the solid content of the negative electrode slurry is 40 wt%. This slurry is applied to the negative electrode current collector (copper foil), dried at 85°C, then cold pressed, cut into pieces, slit, and dried under vacuum conditions at 120°C for 12 hours to obtain the negative electrode.
  • a 7 ⁇ m thick polyethylene (PE) porous polymer film was used as the isolation membrane.
  • the positive electrode, isolation film and negative electrode in order so that the isolation film acts as an isolation between the positive electrode and the negative electrode, then wind it up, weld it behind the tab, place it in the outer packaging foil aluminum plastic film, and inject the electrolyte. After vacuum packaging, standing, formation, shaping, capacity testing and other processes, the soft-packed lithium-ion battery is obtained.
  • the first reversible gram capacity of the negative active material at 0V to 2.0V can be obtained by the following test method: take a single-sided coated negative electrode piece, cut it into a certain area and use it as a working electrode, and then use a lithium piece (or Sodium flakes, etc.) are used as counter electrodes, and porous polyethylene films are used as separators. After injecting electrolyte, a button battery is assembled; the button battery is first discharged to 0V with a three-stage small current of 0.05C/50 ⁇ A/20 ⁇ A, and then the button battery is recorded. First discharge capacity; then charge to 2.0V with a constant current of 0.1C, and record the first charge capacity of the button battery.
  • the specific composition of the electrolyte is not specifically limited.
  • the electrolyte can use a LiPF 6 solution with a concentration of 1 mol/L, and the solvent can be composed of ethylene carbonate (EC) and diethyl carbonate (DEC) according to the mass. Mixed at a ratio of 1:1.
  • Judgment of the degree of lithium evolution based on the state of the fully charged and disassembled negative electrode.
  • the entire negative electrode is black and the gray area is ⁇ 2%, it is judged that lithium is not evolving; when the negative electrode is mostly black, but there are some areas Gray can be observed, and the gray area is between 2% and 20%, then it is judged as slight lithium precipitation; when the negative electrode part is gray, but some black can still be observed, and the gray area is between 20% and 60%, it is judged as lithium precipitation.
  • Lithium when most of the negative electrode appears gray and the gray area is >60%, it is judged to be severe lithium precipitation.
  • H/C value the molar ratio of H element to C element in hard carbon; H element and C element are measured by an elemental analyzer.
  • the testing instrument is a UNICUBE elemental analyzer.
  • the hard carbon is measured after full combustion in a high-purity oxygen environment. The molar content of H 2 O and CO 2 , thus obtaining the molar ratio of the H/C value.
  • the conventional CB value setting of graphite is generally 1.05-1.08.
  • the graphite in Comparative Example 1 is prone to lithium precipitation when the CB value is too small.
  • the CB value can be significantly reduced without lithium precipitation.
  • the H/C value and the CB value cooperate with each other.
  • the negative electrode can be achieved without lithium precipitation, and the lithium-ion battery has a relatively high performance. High energy density.
  • Hard carbon has potential advantages in weight energy density and fast charge and discharge performance, and can be used in power batteries, power tools, drones and other fields.
  • Example 12-13 The preparation method of hard carbon in Examples 12-13 is similar to the preparation method of hard carbon 2, but the particles are specially classified. In Example 12, the small particles are taken from the classification, and in Example 13, the larger particles are taken from the classification. As for the particles, Example 2 is the particle distribution of Example 12 and Example 13 mixed at a mass ratio of 1:1. The specific particle distribution is shown in Table 2. Examples 14-16 are preparation methods for hard carbon 5. Example 16 is the particle distribution of Example 14 and Example 15 mixed according to a mass ratio of 1:1. The relevant parameters are as follows:
  • the value in the DSC column represents the thermal weight loss peak area of the negative electrode piece between 150°C and 220°C.
  • the particle size distribution of the samples is different, which affects the specific surface area of the hard carbon and the compaction density of the negative electrode piece, thereby affecting its energy density.
  • the hard carbon material is matched with small and large particles, it is most beneficial to increase the compaction density of the pole piece and increase the energy density, and the lithium ion embedding and migration distance is appropriate, so that the lithium ion battery can obtain better dynamic performance and improve the pole piece analysis. Lithium situation.
  • the thermal weight loss peak area between 150°C and 220°C in DSC represents the thermal weight loss peak of metalloid lithium in the hard carbon micropores in the negative electrode sheet, indicating that a reasonable combination of hard carbon particles makes the metalloid lithium stored in the same area of the negative electrode sheet more This also reflects the improvement in the energy density of lithium-ion batteries. It can be seen that choosing hard carbon materials with a combination of large and small particles can improve the lithium evolution of the negative electrode of lithium-ion batteries and increase the energy density of lithium-ion batteries. When BET/P is not less than 1.7, it is to avoid excessive accumulation of large particles that may lead to low compaction density and low BET of the pole piece, which may affect the energy density and dynamics of the lithium-ion battery.

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Abstract

电化学装置及包括电化学装置的电子设备，电化学装置包括负极极片，负极极片包括负极活性材料层，负极活性材料层中的负极活性物质包括硬碳，硬碳的H/C值为0.05至0.18，电化学装置的CB值为0.95至1.05。利用硬碳作为负极活性物质，通过调控硬碳的H/C值和电化学装置的CB值，可以实现不析锂的情况下，提高能量密度，即兼顾改善析锂和提高能量密度。

Description

电化学装置及电子设备 技术领域
本申请涉及锂电池技术领域，尤其涉及一种电化学装置及电子设备。
背景技术
锂离子电池具有体积和质量能量密度大、环境友好、工作电压高、体积小、重量轻、循环寿命长等优点，在便携式消费电子领域具有广泛的应用。随着近年来电动汽车和可移动电子设备的高速发展，人们对电池的能量密度、安全性、循环性能等相关需求越来越高，期待着综合性能全面提升的新型锂离子电池的出现；其中，能量密度、循环性能已成为亟待解决的关键技术问题，改进电极中的活性材料是解决上述问题的研究方向之一。
石墨是目前最广泛的负极材料，它具有极化小，充放电平台稳定等优势，然而，目前的商业石墨的性能几乎开发到了极致，在不析锂的前提下，其可逆克容量和能量密度难以得到进一步的提升。因此，开发新的可选择的负极材料是解决目前锂离子电池能量密度低的研究方向之一。
发明内容
本申请实施例提供一种电化学装置及电子设备，利用硬碳作为活性物质，通过调控硬碳的H/C值和电化学装置的CB值，可以实现不析锂的情况下，提高能量密度，即兼顾改善析锂和提高能量密度。
首先，本申请实施例提供了一种电化学装置，包括负极极片，所述负极极片包括负极活性材料层，所述负极活性材料层中的负极活性物质包括硬碳，所述硬碳的H/C值范围为0.05至0.18，所述电化学装置的CB值范围为0.95至1.05；其中，H/C值为硬碳中H元素与C元素的摩尔比，CB值为单位面积负极容量与单位面积正极容量的比值。通过控制硬碳中H元素与C元素的摩尔比在0.05至0.18之间，用以调控负极活性材料层中的H元素与C元素的 摩尔比介于0.1至0.5，负极活性材料层中H元素与C元素的摩尔比在合适的范围内，利于提升活性离子的传输速度，同时，调控所述电化学装置的CB值为0.95至1.05，二者配合，利于提高电化学装置的能量密度，以及改善电化学装置的析锂情况。
通过热分析法测试时，满充状态下(即100％电荷状态)的所述负极极片在150℃至220℃范围内存在热失重峰，且峰面积>100J/g；其中，所述热失重峰为硬碳微孔中类金属锂的热失重峰，其峰面积的大小与电化学装置能量密度的高低趋势一致，即峰面积越大说明极片相同面积储存的类金属锂越多，因此锂离子电池的能量密度越大，通过热失重峰的峰面积用以表征硬碳的储锂特征；在所述负极极片的XRD衍射图谱中，在2倍散射角位于20°至30°范围内存在衍射峰A1，其半峰宽介于3°至10°，衍射峰A1为硬碳的特征峰；所述负极极片的拉曼光谱中，在1320cm -1至1370cm -1范围内存在特征峰D1，其峰强度为I D1，D1为无序化峰，反映碳材料内部的无序化程度，在1570cm -1至1620cm -1范围内存在特征峰G1，其峰强度为I G1，G1为石墨化峰，反映C原子sp 2杂化的面内伸缩振动，且满足0.5≤I D1/I G1≤1.5；通过控制I D1和I G1的峰强比在0.5至1.5之间，使得锂离子具有较高的传输速度，使电化学装置具有较高的能量密度；若峰强比I D1/I G1小于0.5，则说明无序化程度低，硬碳材料储锂位点较少，可逆容量低，影响锂离子电池的倍率性能，若峰强比I D1/I G1大于1.5，则说明无序化程度过高，不利于锂离子的传输，易引起析锂。
此外，所述硬碳的比表面积BET为1.5m 2/g至10m 2/g，若BET值过大(例如大于10m 2/g)则不利于锂离子电池制备过程中阳极极片的加工过程，例如制浆和涂布过程，同时，过大的BET值还会导致锂离子电池首次效率偏低，进而影响能量密度的发挥；而若BET值过小(例如小于1.5m 2/g)还会影响锂离子电池的动力学性能，导致轻微析锂；以及，所述负极极片在5t压力下测试的压实密度为P，且满足：0.85g/cm 3≤P≤1.1g/cm 3；所述硬碳的比表面积BET与压实密度P的比值为M(即BET/P＝M)，满足：M＞1.7。通过控制所述负极极片在5t压力下的压实密度P在合适的范围，利于提升电化学装置的能量密度，同时调控所述硬碳的BET值与负极极片压实密度P的比值大于1.7，用以进一步提升电化学装置的能量密度以及动力学性能的发挥。
所述硬碳在累积体积分布曲线中的50％处颗粒的粒径值Dv50的取值范围为2μm至15 μm，其在累积体积分布曲线中的99％处颗粒的粒径值Dv99的取值范围为8μm至45μm，且其在0V至2.0V克容量为300mAh/g至1200mAh/g；通过控制所述硬碳的粒径范围，若所述硬碳的粒径过小则会导致其BET值过大，一方面不利于锂离子电池制备过程中阳极极片的加工过程，另一方面还会导致制备得到的电化学装置的首次库伦效率低，进而影响能量密度；而若硬碳的粒径过大则不利于提升电化学装置的动力学性能；可见，合适的粒径分布利于改善电化学装置的动力学性能，进而提升能量密度。
其次，所述硬碳的制备过程包括以下步骤：将碳源依次经过前驱体改性处理、第一次煅烧处理、分级处理以及第二次煅烧处理；
前驱体改性处理：当碳源为生物质玉米淀粉时，通常是将其置于空气气氛中于150℃至200℃条件下氧化5h至20h；当碳源为生物质椰壳时，通常是将其置于碱性溶液中浸泡并在150℃至200℃条件下水热5h至20h；当碳源为酚醛树脂时，其与生物质玉米淀粉的处理方法相同；当碳源为沥青时，需将其置于有机溶液中浸泡5h至10h，再分别置于不同的温度下氧化5h至20h，用以完成所述碳源的前驱体改性处理；前驱体改性处理的目的是固定前驱改性过程的孔隙特征，以期在后续碳化过程中得以保留孔隙；第一次煅烧处理：将通过前驱体改性处理后的产物置于惰性气氛中于500℃至600℃煅烧2h至3h，用以初步碳化前驱体，固定碳材料的基本结构；分级处理：将经过第一次煅烧处理后的产物进行破碎分级，用以筛分出所需的颗粒尺寸；第二次煅烧处理：将分级处理后的产物置于惰性气氛下经超高温保温2至3小时，用以消除降低碳材料中的官能团，收缩表面结构，降低比表面积，降低不可逆成分。
当然，需要说明的是，所述第二次煅烧处理的温度通常不高于1000℃，当所述第二次煅烧处理的温度高于1000℃时，在所述第二次煅烧处理后还包括：表面改性包覆处理和第三次煅烧处理；表面改性包覆是通过将第二次煅烧处理后的产物置于10％CH 4/Ar混合气中进行CVD包覆，所述表面改性包覆与所述第三次煅烧处理是同步进行的，即将第二次煅烧处理后的产物置于10％CH 4/Ar混合气中在低于1000℃(第三次煅烧处理)的条件中保温1至3h，用以在碳材料颗粒表面包覆一层碳层；经过所述表面改性包覆处理形成的包覆层的热解温度为700℃至1000℃，通过在所述硬碳的表面覆盖包覆层，用以消除降低碳材料中的不可逆官 能团及开孔成分，同时，控制所述包覆层的热解温度为700℃至1000℃，用以让甲烷沉积并保留一定的H/C值比例，最终得到H/C值为0.05至0.18的硬碳。
最后，本申请实施例提供了一种电子设备，包括上述任意一种电化学装置。
本申请一些实施例提供的技术方案带来的有益效果至少包括：
本发明提供了一种电化学装置，包括负极极片，所述负极极片包括负极活性材料层，所述负极活性材料层中的负极活性物质包括硬碳，所述硬碳的H/C值为0.05至0.18，所述电化学装置的CB值为0.95至1.05。通过控制硬碳中H元素与C元素的摩尔比在0.05至0.18之间，用以调控负极活性材料层中的H元素与C元素的摩尔比介于0.1至0.5，负极活性材料层中H元素与C元素的摩尔比在合适的范围内，利于提升活性离子的传输速度，同时，调控所述电化学装置的CB值为0.95至1.05，利于提高电化学装置的能量密度以及改善电化学装置的析锂情况。
附图说明
为了更清楚地说明本申请实施例或现有技术中的技术方案，下面将对实施例或现有技术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，在不付出创造性劳动的前提下，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2中负极极片的热分析图谱；
图2为本申请实施例2中硬碳颗粒的粒径分布图。
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，并不用于限定本申请。
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。
石墨是目前最广泛的负极材料，它具有极化小，充放电平台稳定等优势，然而，目前的商业石墨为了避免负极析锂的情况发生，一般阳极的容量会大于阴极的容量。这里我们定义单位面积的阳极容量与阴极容量的比例为CB值，CB值＝单位面积阳极的容量/阴极的容量，石墨的CB值一般介于1.04-1.08之间。然而，较高的CB值会导致电池的能量密度较低，因此，现有技术中石墨负极不能很好地兼顾析锂和能量密度等多种性能。
硬碳是一种潜在的可替代石墨的负极材料之一，它的可逆克容量可达石墨负极的1至2倍，因此，当使用硬碳作为石墨的替代品作为锂离子电池的负极材料时，整个锂离子电池的能量密度有望得到一定程度的提升。同时，硬碳具有不同于石墨的物化性能，例如，硬碳的孔隙更丰富，使得其用于锂离子电池负极材料时，相对于石墨更不易析锂；而硬碳作为新的负极材料，具有更丰富的孔隙结构，且相对锂的电位≤0V，因此相比于石墨，低CB值的硬碳更不易析锂；若将所述硬碳按石墨体系进行设计，得到的电化学装置的能量密度ED较低，因此，研究具有不同H/C值和CB值的硬碳体系，利于提高电化学装置的能量密度以及改善电化学装置的析锂情况。
电化学装置
为了解决上述技术问题，本申请提出一种电化学装置，包括负极极片、隔离膜、正极极片和电解液。
负极极片
负极极片包括负极集流体以及设置于所述负极集流体的至少一个表面上的负极活性材料层；所述负极活性材料层中的负极活性物质包括硬碳，所述硬碳的H/C值的取值范围为0.05至0.18，所述电化学装置的CB值的选择范围为0.95至1.05；其中，H/C值为硬碳中H元素与C元素的摩尔比，CB值为单位面积负极容量与单位面积正极容量的比值。
示例性地，所述硬碳的H/C值为0.05、0.08、0.10、0.12、0.14、0.16、0.18或上述任意两个值组成的范围。
示例性地，所述电化学装置的CB值为0.95、0.97、0.99、1.01、1.03、1.05或上述任意两个值组成的范围。
优选地，所述硬碳的H/C值为0.05至0.15。示例性地，所述硬碳的H/C值为0.05、0.06、0.07、0.09、0.11、0.13、0.15或上述任意两个值组成的范围。
进一步优选地，所述硬碳的H/C值为0.08至0.15。示例性地，所述硬碳的H/C值为0.08、0.10、0.11、0.13、0.15或上述任意两个值组成的范围。
优选地，所述电化学装置的CB值为0.96至1.00。示例性地，所述电化学装置的CB值为0.96、0.97、0.98、0.99、1.00或上述任意两个值组成的范围。
进一步优选地，所述电化学装置的CB值为0.98至1.00。示例性地，所述电化学装置的CB值为0.98、0.99、1.00或上述任意两个值组成的范围。
在一些实施方式中，所述电化学装置满足以下条件中的至少一者：
(1)通过热分析法测试时，满充状态下的所述负极极片在150℃至220℃范围内存在热失重峰，且峰面积>100J/g；优选地，峰面积>110J/g。
(2)所述负极极片的XRD衍射图谱中，在20°至30°范围内存在衍射峰A1，其半峰宽介于3°至10°；
示例性地，所述衍射峰A1的半峰宽为3°、5°、8°、10°或上述任意两个值组成的范围。
(4)所述负极极片的拉曼光谱中，在1320cm -1至1370cm -1范围内存在特征峰D1，在1570cm -1至1620cm -1范围内存在特征峰G1，所述特征峰D1的峰强度为I D1，所述特征峰G1的峰强度为I G1，满足0.5≤I D1/I G1≤1.5；
示例性地，所述特征峰D1和所述特征峰G1的峰强比I D1/I G1为0.5、0.8、1.0、1.2、1.5或上述任意两个值组成的范围。
在一些实施方式中，所述电化学装置满足以下条件中的至少一者：
(Ⅰ)所述硬碳的比表面积BET为1.5m 2/g至10m 2/g；
示例性地，所述硬碳的比表面积BET为1.5m 2/g、2m 2/g、4m 2/g、6m 2/g、8m 2/g、10m 2/g或上述任意两个值组成的范围。
(Ⅱ)所述负极极片在5t压力下测试的压实密度为P，满足：0.85g/cm 3≤P≤1.1g/cm 3；
示例性地，所述负极极片在5t压力下测试的压实密度P为0.85g/cm 3、0.88g/cm 30.98g/cm 3、1.1g/cm 3或上述任意两个值组成的范围。
(Ⅲ)所述硬碳的比表面积BET与所述负极极片的压实密度P的比值为M，满足：M＞1.7。
优选地，所述电化学装置满足以下条件中的至少一者：
(Ⅰ′)所述硬碳的比表面积BET为2m 2/g至8m 2/g；
示例性地，所述硬碳的比表面积BET为2m 2/g、3m 2/g、5m 2/g、6m 2/g、8m 2/g或上述任意两个值组成的范围。
(Ⅱ′)所述负极极片在5t压力下测试的压实密度为P，满足：0.98g/cm 3≤P≤1.05g/cm 3；
示例性地，所述负极极片在5t压力下测试的压实密度P为0.98g/cm 3、1.0g/cm 3、1.01g/cm 3、1.03g/cm 3、1.05g/cm 3或上述任意两个值组成的范围。
(Ⅲ′)所述硬碳的比表面积BET与所述负极极片的压实密度P的比值为M，满足：2≤M≤9。
示例性地，所述硬碳的比表面积BET与所述负极极片的压实密度P的比值M为2、3、5、7、9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为负极活性材料层的重量，单位为g；v为负极活性材料层的体积，单位为cm 3。其中负极活性材料层的体积v可以是负极活性材料层的面积S与负极活性材料层的厚度h之积。
负极材料的比表面积可以采取BET测试法(Brunauer-Emmett-Teller，BET)进行测量；首先采用Tri Star Ⅱ比表面分析仪，用样品管装样品3克-6克,再将样品放入脱气站中，对样品进行加热，抽真空，之后关加热及抽真空，使样品温度降至室温，卸下并衡量样品和样品管的质量，再装入分析站分析，进行数据处理及计算。
在一些实施方式中，所述电化学装置满足以下条件中的至少一者：
(a)所述硬碳在累积体积分布曲线中的50％处颗粒的粒径值Dv50的取值范围为2μm至15μm；
示例性地，所述硬碳在累积体积分布曲线中的50％处颗粒的粒径值Dv50为2μm、4μm、6μm、8μm、10μm、12μm、15μm或上述任意两个值组成的范围。
(b)所述硬碳在累积体积分布曲线中的99％处颗粒的粒径值Dv99的取值范围为8μm至45μm；
示例性地，所述硬碳在累积体积分布曲线中的99％处颗粒的粒径值Dv99为8μm、10μm、20μm、30μm、40μm、45μm或上述任意两个值组成的范围。
优选地，所述电化学装置满足以下条件中的至少一者：
(a′)所述硬碳在累积体积分布曲线中的50％处颗粒的粒径值Dv50的取值范围为5μm至7μm；
示例性地，所述硬碳在累积体积分布曲线中的50％处颗粒的粒径值Dv50为5μm、5.5μm、6μm、6.5μm、7μm或上述任意两个值组成的范围。
(b′)所述硬碳在累积体积分布曲线中的99％处颗粒的粒径值Dv99的取值范围为25μm至40μm；
示例性地，所述硬碳在累积体积分布曲线中的99％处颗粒的粒径值Dv99为25μm、30μm、35μm、40μm或上述任意两个值组成的范围。
本申请还公开了所述硬碳的制备过程，包括以下步骤：
将碳源依次经过前驱体改性处理、第一次煅烧处理、分级处理、第二次煅烧处理。
所述前驱体改性处理：当碳源为生物质玉米淀粉时，通常是将其置于空气气氛中于150℃至180℃条件下氧化5h至10h；当碳源为生物质椰壳时，通常是将其置于氢氧化钠溶液中浸 泡并在150℃至180℃条件下水热5h至10h；当碳源为酚醛树脂时，其与生物质玉米淀粉的处理方法相同；当碳源为沥青时，需将其置于喹啉溶液中浸泡5h至8h，再分别置于150℃、200℃、250℃、300℃下氧化5h至10h，用以完成对所述碳源的前驱体改性处理；
所述第一次煅烧处理：将通过前驱体改性处理后的产物置于氩气或氮气气氛中于500℃至550℃煅烧2h；
所述第二次煅烧处理：将分级处理后的产物置于氩气气氛下于700℃至1000℃煅烧2h；当所述第二次煅烧处理的温度高于1000℃时，在所述第二次煅烧处理后还包括：表面改性包覆处理和第三次煅烧处理；所述第三次煅烧处理的温度为700℃至900℃。
在一些实施方式中，所述表面改性包覆处理形成的包覆层的热解温度为700℃至1000℃。
示例性地，所述包覆层的热解温度为700℃、800℃、900℃、1000℃或上述任意两个值组成的范围。
示例性地，所述第三次煅烧温度为850℃、900℃、920℃、950℃或上述任意两个值组成的范围。
负极极片的示例性制备方法：
(1)将硬碳、粘结剂和分散剂按一定重量比溶于溶剂中，形成负极浆料；
(2)将所述负极浆料涂覆于负极集流体上，形成负极活性材料层；
(3)将步骤(2)中涂覆有负极活性材料层的负极集流体，经过干燥、冷压、裁切得到负极极片。
其他
正极极片包括正极集流体及设置于正极集流体至少一个表面上的正极活性材料层，所述正极活性材料层中的正极活性材料可选自锂钴氧化物、锂镍氧化物、锂锰氧化物、锂镍锰氧化物、锂镍钴锰氧化物、锂镍钴铝氧化物、磷酸铁锂以及上述化合物添加其他过渡金属或非过渡金属得到的化合物中的一种或几种。
示例性地，正极集流体可以使用金属箔材或多孔金属板等材料，例如使用铝、铜、镍、钛或铁等金属或它们的合金的箔材或多孔板，如Al(铝)箔。
正极极片可以按照本领域常规方法制备。
对上述隔离膜的种类没有具体的限制，可根据实际需求进行选择。例如，所述隔离膜可以是聚乙烯膜、聚丙烯膜、聚偏氟乙烯膜以及它们的多层复合膜，但不仅限于这些材料。
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)、磺酸酯环状季铵盐、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。
上述电解液可以按照本领域常规的方法制备。
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。
示例部分
1、硬碳材料合成：
硬碳(H/C值介于0.05至0.18)粉末以树脂、生物质材料如椰壳或沥青经过前驱体改性、第一次煅烧、分级、第二次煅烧等工序完成。
硬碳1合成：将生物质玉米淀粉为原料，在空气气氛下180℃氧化5小时(前驱体改性)，然后用管式炉于氩气气氛中500℃煅烧2h(第一次煅烧)，降温后破碎分级(去除400目以下的大颗粒)，然后进行第二次煅烧，于氩气气氛中升温至1000℃，保温2h，降温后获得最终产物，记作硬碳1；
下述实施例中，相同的步骤作用相同，不在赘述。
硬碳2合成：将生物质椰壳破碎至1mm以下后，用清水洗净，装入反应釜中用1M的氢氧化钠溶液浸泡并在180℃水热5小时(前驱体改性)，取出后烘干并用管式炉于氩气气 氛中500℃煅烧2h，降温后破碎分级(去除400目以下的大颗粒)，并用去离子水洗至中性，然后烘干并进行第二次煅烧，于氩气气氛中升温至1100℃，保温2h，后降温；然后在900℃进行CVD包覆，包覆气氛为10％CH 4/Ar混合气(即CH 4占混合气的含量为10wt％)，时间为1h(表面改性包覆及第三次煅烧)，得到的产物记作硬碳2，其中形成的包覆层的热解温度为750℃；
硬碳3的合成与硬碳2类似，仅将第二次煅烧温度改为850℃；不进行CVD包覆和第三次煅烧处理，得到的产物记作硬碳3；
硬碳4的合成与硬碳2类似，仅将第二次煅烧温度改为700℃；不进行CVD包覆和第三次煅烧处理，得到的产物记作硬碳4；
硬碳5合成：以酚醛树脂为原料，在空气气氛下180℃氧化5小时，然后用管式炉于氩气气氛中500℃煅烧2h，降温后破碎分级(去除400目以下的大颗粒)，然后进行第二次煅烧，于氩气气氛中升温至1200℃，保温2h，后降温；然后在900℃进行CVD包覆，包覆气氛为10％CH 4/Ar混合气(即CH 4占混合气的含量为10wt％)，时间为1h，得到的产物记作硬碳5，其中形成的包覆层的热解温度为750℃；
硬碳6的合成与硬碳5类似，仅将第二次煅烧温度改为900℃；不进行CVD包覆和第三次煅烧处理，得到的产物记作硬碳6；
硬碳7的合成与硬碳5类似，仅将第二次煅烧温度改为700℃；不进行CVD包覆和第三次煅烧处理，得到的产物记作硬碳7；
硬碳8合成：以石油沥青为原料，将Dv50为15um的沥青颗粒用喹啉浸泡5小时，抽滤烘干，然后在流动空气气氛下，分别于150℃，200℃，250℃，300℃下各氧化5小时(前驱体改性)，然后用管式炉于氩气气氛中500℃煅烧2h，降温后破碎分级(去除400目以下的大颗粒)，然后进行第二次煅烧，于氩气气氛中升温至1100℃，保温2h，后降温；然后在900℃进行CVD包覆，包覆气氛为10％CH 4/Ar混合气(即CH 4占混合气的含量为10wt％)，时间为1h，得到的产物记作硬碳8；
硬碳9的合成与硬碳8类似，仅将第二次煅烧温度改为900℃；不进行CVD包覆和第三次煅烧处理，得到的产物记作硬碳9；
硬碳10的合成与硬碳8类似，仅将第二次煅烧温度改为700℃；不进行CVD包覆和第三次煅烧处理，得到的产物记作硬碳10；
硬碳11的合成：将生物质椰壳破碎至1mm以下后，用清水洗净，装入反应釜中用1M的氢氧化钠溶液浸泡并在180℃水热5小时(前驱体改性)，取出后烘干并用管式炉于氩气气氛中500℃煅烧2h，降温后破碎分级(去除400目以下的大颗粒)，并用去离子水洗至中性，然后烘干并进行第二次煅烧，于氩气气氛中升温至1200℃，保温2h，后降温；
硬碳12的合成：硬碳12的合成与硬碳2类似，仅将第二次煅烧温度改为600℃；不进行CVD包覆和第三次煅烧处理，得到的产物记作硬碳12；
硬碳13的合成：将生物质椰壳破碎至1mm以下后，用清水洗净，装入反应釜中用1M的氢氧化钠溶液浸泡并在180℃水热5小时(前驱体改性)，取出后烘干并用管式炉于氩气气氛中500℃煅烧2h，降温后破碎分级(去除400目以下的大颗粒)，并用去离子水洗至中性，然后烘干并进行第二次煅烧，于氩气气氛中升温至1000℃，保温2h，后降温；
硬碳14的合成：与硬碳13相同；
石墨为市售人造石墨；
生物质玉米淀粉、生物质椰壳、酚醛树脂和石油沥青均通过商业途径购买获得，如生物质玉米淀粉的购买厂家为阿拉丁试剂、石油沥青的购买厂家为辽宁鸿宇碳素石墨材料有限公司。
2、负极的制备
将上述制备得到的硬碳材料作为负极活性物质、与丁苯橡胶(SBR)和羧甲基纤维素钠(CMC)按照重量比97:2:1在适量的去离子水中充分搅拌混合，使其形成均匀的负极浆料，其中负极浆料的固含量为40wt％。将此浆料涂覆于负极集流体(铜箔)上，在85℃下烘干，然后经过冷压、裁片、分切后，在120℃的真空条件下干燥12小时，得到负极。
3、正极的制备
将正极活性物质钴酸锂(LiCoO 2)、导电剂Super P和粘结剂聚偏二氟乙烯(PVDF)按重量比97:1.4:1.6在适量的N-甲基吡咯烷酮(NMP)溶剂中充分搅拌混合，使其形成均匀的正极浆料，其中正极浆料的固含量为72wt％。将此浆料涂覆于正极集流体铝箔上，在85℃ 下烘干，然后经过冷压、裁片、分切后，在85℃的真空条件下干燥4小时，得到正极。
4、电解液的制备
在干燥的氩气气氛手套箱中，将碳酸乙烯酯(EC)、碳酸甲乙酯(EMC)、碳酸二乙酯(DEC)按照质量比为EC:EMC:DEC＝30:50:20进行混合均匀，加入锂盐LiPF 6，混合均匀后获得电解液，基于电解液的质量，LiPF 6的质量百分含量为12.5％。
5、隔离膜的制备
以7μm厚的聚乙烯(PE)多孔聚合物薄膜作为隔离膜。
6、锂离子电池的制备
将正极、隔离膜、负极按顺序叠好，使隔离膜处于正极和负极之间起到隔离的作用，然后卷绕、焊接极耳后、置于外包装箔铝塑膜中，注入电解液，经过真空封装、静置、化成、整形、容量测试等工序，获得软包锂离子电池。
7、锂离子电池的首次效率的测试方法
所述负极活性材料在0V至2.0V的首次可逆克容量可通过如下测试方法得到：取单面涂覆的负极极片，将其裁切成一定面积后作为工作电极，之后以锂片(或钠片等)作为对电极，以多孔聚乙烯膜作为隔膜，注入电解液后组装得到纽扣电池；将纽扣电池先分别以0.05C/50μA/20μA三阶段小电流放电至0V后，记录纽扣电池的首次放电容量；再以0.1C恒流充电至2.0V，记录纽扣电池的首次充电容量。首次效率＝首次充电容量/首次放电容量*100％；所述负极活性材料在0V至2.0V的首次可逆克容量＝纽扣电池的首次充电容量/负极活性材料的质量。所述电解液的具体组成不受具体的限制，例如，所述电解液可以采用浓度为1mol/L的LiPF 6溶液，溶剂可以由碳酸乙烯酯(EC)和碳酸二乙酯(DEC)按照质量比1:1混合得到。
8、负极析锂情况测试方法
取被测锂离子电池在0℃测试温度下，静置5分钟，以0.8C的电流恒流充电至4.45V，再以4.45V的电压恒压充电至0.05C；静置5分钟，再以0.5C的电流恒流放电至2V，静置5分钟。重复上述充放电流程10次后，将电池满充，于干燥房内拆解，拍照记录负极的状态。
析锂程度判定：根据满充拆解负极的状态来判定，当负极整体显示为黑色且显示为灰色的面积<2％，则判定为不析锂；当负极大部分为黑色，但有部分位置可观察到灰色，灰色 面积在2％至20％之间，则判定为轻微析锂；当负极部分为灰色，但仍可观察到部分黑色，灰色面积在20％至60％，则判定为析锂；当负极大部分显示为灰色，灰色面积＞60％时，则判定为严重析锂。
9、负极材料H/C值比例的定义
H/C值的定义:硬碳中H元素与C元素的摩尔比；H元素与C元素由元素分析仪测定，测试仪器为UNICUBE元素分析仪，将硬碳在高纯氧环境充分燃烧后测定H 2O与CO 2的摩尔含量，从而得出H/C值的摩尔比例。
10、差示扫描量热法(DSC)分析
将满充状态下的锂离子电池，拆解取出负极极片，采用差示扫描量热法，收集负极极片在0-500℃范围内的热失重峰。
表1
Figure PCTCN2022100662-appb-000001
从表1可以看出，一般来说，为了避免析锂，石墨的常规CB值设定一般为1.05-1.08。对比例1中的石墨当CB值过小时容易析锂。而硬碳作为负极材料时，CB值可显著降低而仍不析锂，当H含量低时，如H/C值＝0.05时，CB值最低可到0.96而负极不析锂，且锂离子电池具有较高能量密度。
此外，通过对比例2和对比例3与实施例1-10相比，可以看出，合适的H/C值(0.05 至0.18)可以避免负极析锂，且锂离子电池具有较高的能量密度。
通过对比例4和对比例5与实施例1-10相比，可以看出，，合适的CB值(0.95至1.05)可以避免负极析锂，且锂离子电池具有较高的能量密度。
且从实验数据可以看出，H/C值与CB值二者相互配合，当H/C值与CB值均满足特定的范围值时，才能实现负极不析锂的同时，锂离子电池具有较高的能量密度。
硬碳在重量能量密度及快速充放电性能具有潜在优势，可在动力电池，电动工具，无人机等领域具有潜在用途。
实施例12-13中的硬碳的制备方法与硬碳2的制备方法类似，但对其颗粒进行了特殊分级，其中实施例12为分级中取小颗粒部分，实施例13为分级中取大颗粒部分，实施例2是实施例12与实施例13的按照质量比1：1混合的颗粒分布，具体颗粒分布如表2所示。实施例14-16为硬碳5制备的制备方法，实施例16是实施例14与实施例15的按照质量比1：1混合的颗粒分布，相关参数如下表；
表2
Figure PCTCN2022100662-appb-000002
DSC列的值表示负极极片在150℃至220℃之间的热失重峰面积。
由表2可以看出，样品的颗粒尺寸的分布不同，影响硬碳的比表面积和负极极片的压 实密度，进而影响其能量密度。当硬碳材料采用大小颗粒搭配时，最有利于极片压实密度的提升和能量密度的提高，且锂离子嵌入迁移距离合适，使锂离子电池获得较好的动力学性能，改善极片析锂情况。DSC中150℃至220℃之间的热失重峰面积代表负极极片内硬碳微孔中类金属锂的热失重峰，说明合理的硬碳颗粒搭配使得负极片相同面积储存的类金属锂更多，也反映出锂离子电池能量密度的提升。可见，选择大小颗粒搭配的硬碳材料可改善锂离子电池负极的析锂情况以及提高锂离子电池的能量密度。BET/P不小于1.7时，即避免过多的大颗粒堆积导致的极片压实密度和BET偏低而影响锂离子电池能量密度及动力学的发挥。
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 (9)

  1. 一种电化学装置，其特征在于，包括负极极片，所述负极极片包括负极活性材料层，所述负极活性材料层中的负极活性物质包括硬碳，所述硬碳的H/C值为0.05至0.18，所述电化学装置的CB值为0.95至1.05；
    其中，H/C值为硬碳中H元素与C元素的摩尔比，CB值为单位面积负极容量与单位面积正极容量的比值。
  2. 根据权利要求1所述的电化学装置，其特征在于，所述电化学装置满足以下条件中的至少一者：
    1)所述H/C值为0.05至0.15，优选地，所述H/C值为0.08至0.15；
    2)所述CB值为0.96至1.00，优选地，所述CB值为0.98至1.00。
  3. 根据权利要求1所述的电化学装置，其特征在于，所述电化学装置满足以下条件中的至少一者：
    (1)通过热分析法测试，满充状态下的所述负极极片在150℃至220℃范围内存在热失重峰，且峰面积>100J/g；
    (2)所述负极极片的XRD衍射图谱中，在20°至30°范围内存在衍射峰A1，其半峰宽介于3°至10°；
    (3)所述负极极片的拉曼光谱中，在1320cm -1至1370cm -1范围内存在特征峰D1，在1570cm -1至1620cm -1范围内存在特征峰G1，所述特征峰D1的峰强度为I D1，所述特征峰G1的峰强度为I G1，满足0.5≤I D1/I G1≤1.5。
  4. 根据权利要求1所述的电化学装置，其特征在于，所述电化学装置满足以下条件中的至少一者：
    (Ⅰ)所述硬碳的比表面积BET为1.5m 2/g至10m 2/g；
    (Ⅱ)所述负极极片在5t压力下测试的压实密度为P，满足：0.85g/cm 3≤P≤1.1g/cm 3；
    (Ⅲ)所述硬碳的比表面积BET与所述压实密度P的比值为M，满足：M＞1.7。
  5. 根据权利要求1所述的电化学装置，其特征在于，所述电化学装置满足以下条件中的至少一者：
    (a)所述硬碳在累积体积分布曲线中的50％处颗粒的粒径值Dv50的取值范围为2μm至15μm；
    (b)所述硬碳在累积体积分布曲线中的99％处颗粒的粒径值Dv99的取值范围为8μm至45μm；
  6. 根据权利要求1至5中任一项所述的电化学装置，其特征在于，所述电化学装置满足以下条件中的至少一者：
    (ⅰ)所述硬碳的比表面积BET为2m 2/g至8m 2/g；
    (ⅱ)所述负极极片在5t压力下测试的压实密度为P，满足：0.98g/cm 3≤P≤1.05g/cm 3；
    (ⅲ)所述硬碳的比表面积BET与所述压实密度P的比值为M，满足：2≤M≤9。
    (ⅳ)所述硬碳在累积体积分布曲线中的50％处颗粒的粒径值Dv50的取值范围为5μm至7μm；
    (ⅴ)所述硬碳在累积体积分布曲线中的99％处颗粒的粒径值Dv99的取值范围为25μm至40μm。
  7. 根据权利要求1所述的电化学装置，其特征在于，所述硬碳的制备过程包括以下步骤：
    将碳源依次经过前驱体改性处理、第一次煅烧处理、分级处理、第二次煅烧处理；
    所述碳源包括树脂、生物质碳材料、沥青中任一种；
    优选地，当所述第二次煅烧处理的温度高于1000℃时，在所述第二次煅烧处理后还包括：表面改性包覆处理和第三次煅烧处理。
  8. 根据权利要求7所述的电化学装置，其特征在于，所述表面改性包覆处理形成包覆层；
    所述包覆层的热解温度为700℃至1000℃，所述第三次煅烧处理的温度为700℃至900℃。
  9. 一种电子设备，包括权利要求1至8中任一项所述的电化学装置。
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* Cited by examiner, † Cited by third party
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JPH06187974A (ja) * 1992-12-16 1994-07-08 Osaka Gas Co Ltd 負極材とその製造方法およびリチウム二次電池
CN104094458A (zh) * 2012-02-06 2014-10-08 株式会社吴羽 非水电解质二次电池用碳质材料
CN104412425A (zh) * 2012-09-06 2015-03-11 株式会社吴羽 非水电解质二次电池负极用碳质材料及其制造方法
CN105514350A (zh) * 2014-09-25 2016-04-20 东莞新能源科技有限公司 锂离子电池
CN109449446A (zh) * 2018-10-17 2019-03-08 宁德时代新能源科技股份有限公司 二次电池

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH06187974A (ja) * 1992-12-16 1994-07-08 Osaka Gas Co Ltd 負極材とその製造方法およびリチウム二次電池
CN104094458A (zh) * 2012-02-06 2014-10-08 株式会社吴羽 非水电解质二次电池用碳质材料
CN104412425A (zh) * 2012-09-06 2015-03-11 株式会社吴羽 非水电解质二次电池负极用碳质材料及其制造方法
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CN109449446A (zh) * 2018-10-17 2019-03-08 宁德时代新能源科技股份有限公司 二次电池

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