WO2024036469A1 - 改性负极材料及其制备方法、负极片、二次电池及用电装置 - Google Patents

改性负极材料及其制备方法、负极片、二次电池及用电装置 Download PDF

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WO2024036469A1
WO2024036469A1 PCT/CN2022/112711 CN2022112711W WO2024036469A1 WO 2024036469 A1 WO2024036469 A1 WO 2024036469A1 CN 2022112711 W CN2022112711 W CN 2022112711W WO 2024036469 A1 WO2024036469 A1 WO 2024036469A1
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negative electrode
electrode material
modified
silicate
secondary battery
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PCT/CN2022/112711
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English (en)
French (fr)
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徐宁波
陈培培
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宁德时代新能源科技股份有限公司
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Priority to PCT/CN2022/112711 priority Critical patent/WO2024036469A1/zh
Publication of WO2024036469A1 publication Critical patent/WO2024036469A1/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
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • 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
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers

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  • the present application relates to the field of batteries, and specifically relates to a modified negative electrode material and a preparation method thereof, a negative electrode sheet, a secondary battery and an electrical device.
  • Secondary batteries are increasingly widely used because of their clean and renewable characteristics. They have the advantages of high energy density, small self-discharge, and superior cycle performance.
  • Secondary batteries mainly rely on the movement of active ions between the positive and negative electrodes to generate electrical energy.
  • active ions are deintercalated from the positive electrode and embedded in the negative electrode through the electrolyte. The opposite is true during discharge.
  • active ions such as lithium ions will cause the expansion and contraction of the negative electrode sheet, causing damage to the structure of the negative electrode material.
  • this application provides a modified negative electrode material and a preparation method thereof, a negative electrode sheet, a secondary battery and a power device, aiming to improve the cycle performance of the secondary battery.
  • the modified negative electrode material includes a negative electrode active base material and a silicate group connected to the negative electrode active base material through oxygen atoms, so The structure of the silicate group is shown in formula (1):
  • each R 1 is independently selected from a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, or a substituted or unsubstituted alkenyl group having 1 to 10 carbon atoms;
  • silicate groups are connected through oxygen atoms on the surface of the negative active substrate.
  • the structure of this silicate is similar to that of orthosilicic acid. It can decompose to form silicic acid during the charge and discharge process. It then reacts with the cations in the electrolyte to form silicate.
  • silicate is alkaline and can remove acidic substances produced in the electrolyte and inhibit damage to the interface structure by HF.
  • silicate has certain The viscosity can be loaded on the surface of the negative electrode sheet to play a stabilizing effect and improve the interface stability of the negative electrode sheet, thereby reducing the resistance of the secondary battery and improving the cycle performance of the secondary battery.
  • each R 1 is independently selected from a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms.
  • each R 1 is independently selected from substituted or unsubstituted alkyl groups having 1 to 4 carbon atoms.
  • the cycle performance of the secondary battery can be further improved.
  • each R 1 is independently selected from an unsubstituted alkyl group having 1 to 4 carbon atoms or an alkyl group having 1 to 4 carbon atoms substituted by halogen.
  • each R 1 is independently selected from any one of methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl and their halides.
  • the silicate group satisfies at least one of the following conditions (a) to (b):
  • the thickness of the coating layer is 1 nm to 20 nm.
  • the negative active substrate includes at least one of a carbon substrate and a silicon substrate.
  • a second aspect of this application provides a method for preparing a modified negative electrode material, including the following steps:
  • the surface of the negative active substrate contains hydroxyl groups; R 1 in formula (2) is the same as R 1 in the first aspect.
  • the above-mentioned modified negative electrode material is obtained by performing a transesterification reaction between the compound of formula (2) and the hydroxyl group on the negative electrode active substrate.
  • the temperature of the transesterification reaction is 50°C to 80°C, and the time is 6h to 24h.
  • the mass ratio of the compound of formula (2) to the negative active substrate is (0.05-1):10.
  • the transesterification reaction is carried out under the action of a transesterification catalyst, and the transesterification catalyst satisfies at least one of the following conditions (c) to (d):
  • the transesterification catalyst includes at least one of a basic catalyst, an acidic catalyst and an organosilane;
  • the transesterification catalyst includes at least one of an inorganic base, an organic base, an inorganic acid, an organic acid and an organochlorosilane;
  • the transesterification catalyst includes at least one of sodium hydroxide, potassium hydroxide, hydrochloric acid, sulfuric acid, ammonia water and dimethyldichlorosilane;
  • the transesterification reaction is carried out in an organic solvent, and the organic solvent satisfies at least one of the following conditions (e) to (f):
  • the organic solvent includes at least one of carbonate solvents, carboxylate solvents, alcohol solvents and ether solvents;
  • the organic solvent includes at least one of dimethyl carbonate, ethyl methyl carbonate, ethanol and ethylene glycol dimethyl ether;
  • a third aspect of the present application provides a negative electrode sheet, which includes a current collector and a negative active layer disposed on the surface of the current collector.
  • the components of the negative active layer include the modified negative electrode of the first aspect. material or the modified negative electrode material prepared by the preparation method of the modified negative electrode material of the second aspect.
  • the mass proportion of the modified negative electrode material in the negative electrode active layer is 70% to 99.5%.
  • a fourth aspect of the present application provides a secondary battery, which includes the negative electrode sheet of the third aspect of the present application.
  • the surface of the negative active layer in the negative electrode sheet is loaded with silicate, and the silicic acid group in the silicate is derived from the decomposition of the silicate ester group.
  • a fifth aspect of the present application provides an electrical device, which includes the secondary battery of the fourth aspect of the present application.
  • FIG. 1 is a schematic diagram of an embodiment of a secondary battery.
  • FIG. 2 is an exploded view of FIG. 1 .
  • Figure 3 is a schematic diagram of an embodiment of a battery pack.
  • FIG. 4 is an exploded view of FIG. 3 .
  • FIG. 5 is a schematic diagram of an embodiment of a power consumption device in which a secondary battery is used as a power source.
  • an embodiment means that a particular feature, structure or characteristic described in connection with the embodiment can be included in at least one embodiment of the present application.
  • the appearances of this phrase in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. Those skilled in the art understand, both explicitly and implicitly, that the embodiments described herein may be combined with other embodiments.
  • multiple refers to more than two (including two).
  • multiple groups refers to two or more groups (including two groups), and “multiple pieces” refers to It is more than two pieces (including two pieces).
  • the instability of the negative electrode sheet interface limits the improvement of the cycle performance of the secondary battery.
  • functional agents are often added to the electrolyte to form a coating film on the negative electrode interface in situ during the charge and discharge process to improve the interface stability, or the negative electrode material is directly surface-coated to improve the stability of the interface. Interface stability.
  • the technicians of this application found during the actual production process that in the method of forming a coating film in situ by adding functional agents to the electrolyte, the inorganic components of the formed interface inner layer are mostly oxides or crystalline structures. Salt, this inorganic layer is easily broken during the volume change process of removing/inserting lithium, resulting in direct contact between the active component and the electrolyte, causing excessive consumption of the electrolyte and active lithium, which will instead worsen the performance of the cell; and directly affect the performance of the battery cell.
  • the negative electrode material is surface-coated, the bonding between the interface formed and the negative electrode is unstable. Especially there are still big problems with the stability under high SOC conditions, which cannot meet people's increasing demand for secondary battery cycle performance. .
  • the modified negative electrode material includes a negative electrode active base material and a silicate group connected to the negative electrode active base material through oxygen atoms.
  • the structure of the silicate ester group As shown in formula (1):
  • each R 1 is independently selected from a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, or a substituted or unsubstituted alkenyl group having 1 to 10 carbon atoms;
  • silicate groups are connected through oxygen atoms on the surface of the negative active substrate.
  • the structure of this silicate is similar to that of orthosilicic acid. It can decompose during the charge and discharge process to generate silicon.
  • silicate is alkaline and can remove acidic substances produced in the electrolyte and inhibit damage to the interface structure by HF.
  • silicate has a certain viscosity and can be loaded on the negative electrode sheet. The surface plays a stabilizing role and can improve the interface stability of the negative electrode sheet, thereby reducing the resistance of the secondary battery and improving the cycle performance of the secondary battery.
  • the structure of the above modified negative electrode material is as follows:
  • M represents the negative active substrate.
  • the value of the number of carbon atoms includes the minimum value and maximum value of the range, as well as every integer value between the minimum value and the maximum value. Specific examples include but are not limited to implementation The point values in the example are: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10.
  • each R 1 is independently selected from an unsubstituted alkyl group having 1 to 10 carbon atoms or an alkyl group having 1 to 10 carbon atoms substituted by halogen.
  • the number of halogen atoms in the alkyl group having 1 to 10 carbon atoms substituted by halogen is not particularly limited.
  • the alkyl group having 1 to 10 carbon atoms substituted by halogen contains at least one halogen atom.
  • the alkyl group having 1 to 10 carbon atoms substituted by halogen contains at least two halogen atoms.
  • the alkyl group having 1 to 10 carbon atoms substituted by halogen contains at least three halogen atoms.
  • halogen includes at least one of fluorine, chlorine, bromine, and iodine.
  • each R 1 is independently selected from an unsubstituted alkyl group having 1 to 10 carbon atoms or an alkyl group having 1 to 10 carbon atoms substituted by halogen.
  • each R 1 is independently selected from a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms.
  • each R 1 is independently selected from a substituted or unsubstituted alkyl group having 1 to 4 carbon atoms.
  • the cycle performance of the secondary battery can be further improved.
  • each R 1 is independently selected from an unsubstituted alkyl group having 1 to 4 carbon atoms or an alkyl group having 1 to 4 carbon atoms substituted by halogen.
  • each R 1 is independently selected from an unsubstituted linear alkyl group having 1 to 4 carbon atoms or a halogen-substituted linear alkyl group having 1 to 4 carbon atoms.
  • each R 1 is independently selected from any one of methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl and their halides.
  • each R1 is independently selected from methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, chloromethyl, dichloromethyl, chloroethyl, dichloroethyl any one of the bases.
  • the proportion of the above-mentioned silicate groups in the modified negative electrode material is 0.005wt% to 5wt%.
  • the above-mentioned silicate group is supported on the surface of the negative electrode active substrate to form a coating layer.
  • silicate groups are supported on the surface of the negative electrode active substrate, they aggregate to form a coating layer to coat the negative electrode active substrate.
  • the thickness of the above-mentioned coating layer is 1 nm to 20 nm.
  • the above-mentioned negative electrode active substrate includes at least one of a carbon substrate and a silicon substrate.
  • the above-mentioned negative active substrate may be selected from, but is not limited to: graphite, soft carbon, hard carbon, mesocarbon microspheres, carbon fiber, carbon nanotubes, elemental silicon, silicon oxide compounds, silicon carbon composites, or these.
  • the material is one or more compounds obtained by adding transition metals or non-transition metals.
  • the above-mentioned negative electrode active substrate is selected from at least one of graphite, elemental silicon, silicon oxide compounds, and silicon carbon composites.
  • One embodiment of the present invention provides a method for preparing a modified negative electrode material, including the following step S10.
  • Step S10 perform a transesterification reaction between the negative electrode active base material and the compound of formula (2) to prepare a modified negative electrode material
  • the surface of the negative electrode active substrate contains hydroxyl groups; R 1 in formula (2) is the same as R 1 in the first aspect.
  • the above-mentioned modified negative electrode material is obtained by performing a transesterification reaction between the compound of formula (2) and the hydroxyl group on the negative electrode active substrate.
  • M represents the negative electrode active substrate.
  • the selection of the negative electrode active substrate is the same as above and will not be described again here.
  • the above-mentioned negative electrode active substrate can be a conventional negative electrode active substrate that has not been activated in the art, or can be a negative electrode active substrate that has been activated to form hydroxyl groups on the surface. It can be understood that the commonly used negative active substrates in this field include silicon-based negative active materials and carbon-based negative active materials, which have abundant hydroxyl groups distributed on their surfaces.
  • the compound of formula (2) is different from the hydroxyl groups on conventional negative active substrates.
  • the above-mentioned modified negative electrode material can be obtained by carrying out transesterification reaction, or the conventional negative electrode active substrate can be modified by activation treatment to further form more abundant hydroxyl groups on the surface, and then react with the compound of formula (2).
  • the temperature of the above-mentioned transesterification reaction is 50°C to 80°C, and the time is 6h to 24h.
  • the mass ratio of the compound of formula (2) to the negative active base material is (0.05-1):10.
  • the hydroxyl groups on the surface of the negative electrode active substrate can react with the compound of formula (2) as much as possible.
  • the above-mentioned transesterification reaction is carried out under the action of a transesterification catalyst.
  • the above-mentioned transesterification catalyst includes at least one of a basic catalyst, an acidic catalyst and an organosilane.
  • the above-mentioned transesterification catalyst includes at least one of inorganic base, organic base, inorganic acid, organic acid and organochlorosilane;
  • the above-mentioned transesterification catalyst includes at least one of sodium hydroxide, potassium hydroxide, hydrochloric acid, sulfuric acid, ammonia water and dimethyldichlorosilane.
  • the mass ratio of the above-mentioned transesterification catalyst to the above-mentioned negative electrode active base material is (0.01-0.5):10.
  • the above-mentioned transesterification reaction is carried out in an organic solvent.
  • the above-mentioned organic solvent includes at least one of carbonate solvents, carboxylate solvents, alcohol solvents and ether solvents.
  • the above-mentioned organic solvent includes at least one of dimethyl carbonate, methyl ethyl carbonate, ethanol and ethylene glycol dimethyl ether.
  • the mass ratio of the above-mentioned organic solvent to the above-mentioned negative electrode active base material is (10-300):10.
  • the compound of formula (2) is selected from at least one of tetramethyl silicate, tetrabutyl silicate, tetraethyl silicate, tetrapropyl silicate and tetrahexyl silicate.
  • One embodiment of the present application also provides a negative electrode sheet, which includes a current collector and a negative active layer disposed on the surface of the current collector.
  • the components of the negative active layer include the above-mentioned modified negative electrode material or the preparation method of the above-mentioned modified negative electrode material.
  • the prepared modified negative electrode material is the above-mentioned modified negative electrode material or the preparation method of the above-mentioned modified negative electrode material.
  • the pole piece has low impedance and can maintain a stable interface during charging and discharging, thereby improving the cycle performance of the secondary battery.
  • the mass proportion of the modified negative electrode material in the negative electrode active layer is 70% to 99.5%.
  • the components of the above-mentioned negative electrode active layer further include a negative electrode conductive agent and a negative electrode binder.
  • the above-mentioned negative conductive agent can use conductive materials commonly used in the art, including but not limited to: at least one of graphite, carbon nanotubes, nanofibers, carbon black, and graphene. Specifically, it can be selected from at least one of SP, KS-6, acetylene black, Ketjen black ECP with branched chain structure, SFG-6, vapor-grown carbon fiber VGCF, carbon nanotube CNTs, graphene and its composite conductive agent. kind.
  • the weight ratio of the negative electrode conductive agent in the negative electrode active layer is 0 to 20 wt%.
  • the above-mentioned negative electrode binder can be a binder commonly used in this field, which can be selected from styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA) ), at least one of sodium alginate (SA), polymethacrylic acid (PMAA) and carboxymethyl chitosan (CMCS).
  • SBR styrene-butadiene rubber
  • PAA polyacrylic acid
  • PAAS sodium polyacrylate
  • PAM polyacrylamide
  • PVA polyvinyl alcohol
  • SA sodium alginate
  • PMAA polymethacrylic acid
  • CMCS carboxymethyl chitosan
  • the weight ratio of the negative electrode binder in the negative electrode active layer is 0 to 30 wt%.
  • the negative active layer may optionally include other auxiliaries, such as thickeners, such as sodium carboxymethylcellulose (CMC-Na), and the like. Based on the total weight of the negative electrode active layer, the weight ratio of other additives in the negative electrode active layer is 0 to 15 wt%.
  • auxiliaries such as thickeners, such as sodium carboxymethylcellulose (CMC-Na), and the like. Based on the total weight of the negative electrode active layer, the weight ratio of other additives in the negative electrode active layer is 0 to 15 wt%.
  • the current collector in the negative electrode sheet can be a metal foil or a composite current collector.
  • the metal foil copper foil can be used.
  • the composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base layer.
  • the composite current collector can be formed by forming metal materials (aluminum, aluminum alloys, nickel, nickel alloys, titanium, titanium alloys, silver and silver alloys, etc.) on polymer material substrates (such as polypropylene (PP), polyterephthalate It is formed on substrates such as ethylene glycol ester (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).
  • PP polypropylene
  • PBT polybutylene terephthalate
  • PS polystyrene
  • PE polyethylene
  • the negative electrode sheet can be prepared in the following manner: the above-mentioned components for preparing the negative electrode sheet, such as modified negative electrode active materials, conductive agents, binders and any other components are dispersed in a solvent (such as deionized water) to form a negative electrode slurry; the negative electrode slurry is coated on the negative electrode current collector, and after drying, cold pressing and other processes, the negative electrode sheet can be obtained.
  • a solvent such as deionized water
  • the solid content of the negative electrode slurry is 30wt% ⁇ 70wt%, and the viscosity at room temperature is adjusted to 2000mPa ⁇ s ⁇ 10000mPa ⁇ s; the obtained negative electrode slurry is coated on the negative electrode current collector, and after a drying process, cold pressing For example, rolls can be used to obtain negative electrode sheets.
  • the negative electrode powder coating unit area density is 75mg/m 2 ⁇ 220mg/m 2
  • the negative electrode sheet compacted density is 1.2g/m 3 ⁇ 2.0g/m 3 .
  • An embodiment of the present application provides a secondary battery including the above-mentioned negative electrode sheet.
  • This secondary battery has excellent cycle performance.
  • the above-mentioned secondary battery may be a sodium-ion battery, a lithium-ion battery, or a potassium-ion battery.
  • the above-mentioned secondary battery further includes a positive electrode sheet, an electrolyte and a separator.
  • positive electrode sheets and electrolyte isolation membranes are given below, but are not limited to the following ranges.
  • the positive electrode sheet includes a current collector and a positive electrode active layer disposed on the surface of the current collector.
  • the components of the positive electrode active layer include positive electrode active materials.
  • the current collector in the positive electrode sheet has two surfaces opposite in its own thickness direction, and the positive active material layer is disposed on any one or both of the two opposite surfaces of the positive electrode current collector.
  • the current collector in the positive electrode sheet can be a metal foil or a composite current collector.
  • the metal foil aluminum foil can be used.
  • the composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base layer.
  • the composite current collector can be formed by forming metal materials (aluminum, aluminum alloys, nickel, nickel alloys, titanium, titanium alloys, silver and silver alloys, etc.) on polymer material substrates (such as polypropylene (PP), polyterephthalate It is formed on substrates such as ethylene glycol ester (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).
  • PP polypropylene
  • PBT polybutylene terephthalate
  • PS polystyrene
  • PE polyethylene
  • the above-mentioned positive electrode active material can be a commonly used positive electrode active material in this application, such as a lithium ion positive electrode active material or a sodium ion positive electrode active material.
  • the lithium ion active material may include at least one of the following materials: olivine-structured lithium-containing phosphates, lithium transition metal oxides, and their respective modified compounds.
  • the present application is not limited to these materials, and other traditional materials that can be used as positive electrode active materials of batteries can also be used. Only one type of these positive electrode active materials may be used alone, or two or more types may be used in combination.
  • lithium transition metal oxides may include, but are not limited to, lithium cobalt oxides (such as LiCoO 2 ), lithium nickel oxides (such as LiNiO 2 ), lithium manganese oxides (such as LiMnO 2 , LiMn 2 O 4 ), lithium Nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (such as LiNi 1/3 Co 1/3 Mn 1/3 O 2 (also referred to as NCM333), LiNi 0.5 Co 0.2 Mn 0.3 O 2 (can also be abbreviated to NCM523), LiNi 0.5 Co 0.25 Mn 0.25 O 2 (can also be abbreviated to NCM211), LiNi 0.6 Co 0.2 Mn 0.2 O 2 (can also be abbreviated to NCM622), LiNi 0.8 Co 0.1 Mn 0.1 O 2 (also referred to as NCM811), at least one of lithium nickel cobalt aluminum oxide (such as LiNi 0.85 Co 0.15),
  • lithium-containing phosphates with an olivine structure may include but is not limited to at least one of lithium iron phosphate (such as LiFePO 4 (also referred to as LFP)), lithium manganese phosphate (such as LiMnPO 4 ), and lithium iron manganese phosphate.
  • lithium iron phosphate such as LiFePO 4 (also referred to as LFP)
  • lithium manganese phosphate such as LiMnPO 4
  • lithium iron manganese phosphate lithium iron manganese phosphate.
  • the molecular formula of the lithium ion active material is: LiFex Mn (1-x) PO 4 , and x is any number from 0 to 1.
  • LiFe x Mn (1-x) PO 4 is LiMnPO 4 lithium manganese phosphate
  • LiFePO 4 is LiFePO 4 lithium iron phosphate (LFP).
  • the sodium ion active material may include at least one of the following materials: at least one of sodium transition metal oxides, polyanionic compounds, and Prussian blue compounds.
  • the present application is not limited to these materials, and other conventionally known materials that can be used as positive electrode active materials of sodium ion batteries can also be used.
  • the transition metal in the sodium transition metal oxide, includes at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr and Ce.
  • the sodium transition metal oxide is, for example, Na x MO 2 , where M includes at least one or more of Ti, V, Mn, Co, Ni, Fe, Cr and Cu, 0 ⁇ x ⁇ 1.
  • the polyanionic compound may be a type of compound having sodium ions, transition metal ions and tetrahedral (YO 4 ) n- anion units.
  • Transition metals include at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr and Ce;
  • Y includes at least one of P, S and Si;
  • n represents (YO 4 ) n -valency.
  • Polyanionic compounds may also be compounds having sodium ions, transition metal ions, tetrahedral (YO 4 ) n- anion units and halogen anions.
  • Transition metals include at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr and Ce;
  • Y includes at least one of P, S and Si, n represents (YO 4 )
  • the valence state of n- ; the halogen can be at least one of F, Cl and Br.
  • Polyanionic compounds may also be a class of compounds having sodium ions, tetrahedral (YO 4 ) n- anion units, polyhedral units (ZO y ) m+ , and optionally halogen anions.
  • Y includes at least one of P, S and Si
  • n represents the valence state of (YO 4 ) n-
  • Z represents a transition metal, including at least Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V , Zr and Ce
  • m represents the valence state of (ZO y ) m+
  • the halogen can be at least one of F, Cl and Br.
  • polyanionic compounds are NaFePO 4 , Na 3 V 2 (PO 4 ) 3 (sodium vanadium phosphate, NVP for short), Na 4 Fe 3 (PO 4 ) 2 (P 2 O 7 ), NaM'PO 4 F(M ' is one or more of V, Fe, Mn and Ni) and at least one of Na 3 (VO y ) 2 (PO 4 ) 2 F 3-2y (0 ⁇ y ⁇ 1).
  • Prussian blue compounds can be compounds containing sodium ions, transition metal ions and cyanide ions (CN - ).
  • the transition metal includes at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr and Ce.
  • Prussian blue compounds are, for example, Na a Me b Me' c (CN) 6 , wherein Me and Me' each independently include at least one of Ni, Cu, Fe, Mn, Co and Zn, 0 ⁇ a ⁇ 2 , 0 ⁇ b ⁇ 1, 0 ⁇ c ⁇ 1.
  • the weight ratio of the cathode active material in the cathode active layer is 80 wt% to 100 wt%.
  • the components of the positive electrode active layer further include a positive electrode conductive agent and a positive electrode binder.
  • the above-mentioned positive electrode conductive agent can use conductive agents commonly used in the art, including but not limited to: at least one of graphite, carbon nanotubes, nanofibers, carbon black and graphene. Specifically, it can be selected from at least one of SP, KS-6, acetylene black, Ketjen black ECP with branched structure, SFG-6, vapor-grown carbon fiber VGCF, carbon nanotube CNTs, graphene and its composite conductive agent. kind.
  • the weight ratio of the positive electrode conductive agent in the positive electrode active layer is 0 to 20 wt%.
  • the binder of the above-mentioned positive electrode binder may be polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, Ethylene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, hydrogenated nitrile rubber, styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), At least one of polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), carboxymethyl chitosan (CMCS) and fluorine-containing acrylate resin.
  • PVDF polyvinylidene fluoride
  • PTFE polytetrafluoroethylene
  • PTFE vinyl
  • the weight ratio of the positive electrode binder in the positive electrode active layer is 0 to 30 wt%.
  • the positive electrode sheet can be prepared in the following manner: dispersing the above-mentioned components for preparing the positive electrode sheet in a solvent (such as N-methylpyrrolidone) to form a positive electrode slurry; coating the positive electrode slurry Covered on the current collector, after drying, cold pressing and other processes, the positive electrode sheet can be obtained.
  • a solvent such as N-methylpyrrolidone
  • the solid content of the positive electrode slurry is 40wt% ⁇ 80wt%, and the viscosity at room temperature is adjusted to 5000mPa ⁇ s ⁇ 25000mPa ⁇ s.
  • the positive electrode slurry is coated on the surface of the positive electrode current collector, dried and cold pressed by a cold rolling mill to form Positive electrode piece; the positive electrode powder coating unit area density is 150 ⁇ 350 mg/m 2 , the positive electrode piece compacted density is 3.0 ⁇ 3.6g/cm 3 , optional 3.3 ⁇ 3.5g/cm 3 .
  • the formula for calculating compacted density is:
  • Compaction density coating surface density / (thickness of electrode piece after extrusion - thickness of current collector).
  • Electrolyte includes electrolyte salt and solvent
  • the electrolyte salt may be selected from electrolyte salts commonly used in the art, including lithium ion electrolyte salts and sodium ion electrolyte salts.
  • the lithium ion electrolyte salt is selected from: lithium hexafluorophosphate (LiPF 6 ), lithium tetrafluoroborate (LiBF 4 ), lithium perchlorate (LiClO 4 ), lithium hexafluoroarsenate (LiAsF 6 ), bisfluorosulfonimide Lithium (LiFSI), lithium bistrifluoromethanesulfonyl imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluoromethanesulfonate borate (LiDFOB), lithium difluoromethanesulfonylborate (LiBOB), lithium difluorophosphate ( One or more of LiPO 2 F 2 ), lithium difluorodioxalate phosphate (LiDFOP), Li(FSO 2 ) 2 N, LiCF 3 SO 3 and lithium tetrafluorooxalate phosphate (LiPF
  • the surface of the negative electrode active layer in the above-mentioned negative electrode sheet is loaded with silicate, and the silicic acid group in the silicate is derived from the decomposition of the silicate ester group.
  • silicate groups connected to the surface of the negative active substrate can decompose, thereby generating silicate.
  • silicate is alkaline, and some lithium silicate salts and acidic substances The combination can remove the acidic substances produced in the electrolyte and inhibit the damage to the interface structure caused by HF.
  • silicate has a certain viscosity, and some silicates can be loaded on the surface of the negative electrode sheet to play a stabilizing role. Improving the interface stability of the negative electrode sheet can reduce the resistance of the secondary battery and improve the cycle performance of the secondary battery.
  • the cationic groups in the above-mentioned silicate are derived from the components of the electrolyte, and further, are derived from the cations in the electrolyte salt.
  • the electrolyte salt is a sodium ion electrolyte salt
  • sodium silicate is formed
  • the electrolyte salt is potassium.
  • the electrolyte salt is an ionic electrolyte salt
  • potassium silicate is formed
  • the electrolyte salt is a lithium ion electrolyte salt
  • lithium silicate is formed.
  • the above-mentioned silicate can be the above-mentioned lithium silicate, or it can be sodium silicate or potassium silicate.
  • Lithium silicate, sodium silicate or potassium silicate all have properties similar to "water glass”. ” properties, with a certain viscosity, such as sodium silicate, Li 4 SiO 4 , Li 2 SiO 3 and Li 2 SiO 5 , etc.
  • the solvent may be selected from fluoroethylene carbonate (FEC), ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methylpropyl carbonate (MPC), ethylpropyl carbonate (EPC), butylene carbonate (BC), methyl formate (MF), Methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate ( One of MB), ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), methyl ethyl sulfone (EMS) and diethyl s
  • FEC fluoro
  • the concentration of the electrolyte salt is usually 0.5 mol/L to 15 mol/L.
  • the electrolyte solution optionally further includes additives.
  • additives may include negative electrode film-forming additives, positive electrode film-forming additives, and may also include additives that can improve certain properties of the battery, such as additives that improve battery overcharge performance, additives that improve battery high-temperature or low-temperature performance, etc.
  • the isolation film is located between the positive electrode sheet and the negative electrode sheet.
  • isolation membrane there is no particular restriction on the type of isolation membrane in this application. Any well-known porous structure isolation membrane with good chemical stability and mechanical stability can be used.
  • the material of the isolation membrane can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride.
  • the isolation film can be a single-layer film or a multi-layer composite film, with no special restrictions. When the isolation film is a multi-layer composite film, the materials of each layer can be the same or different, and there is no particular limitation.
  • the above-mentioned secondary battery also includes a casing for packaging the positive electrode sheet, the negative electrode sheet, the isolation film and the electrolyte.
  • the above-mentioned shell may be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc. It can also be a soft bag, such as a bag-type soft bag.
  • the material of the soft bag may be plastic, and examples of the plastic include polypropylene, polybutylene terephthalate, polybutylene succinate, and the like.
  • FIG. 1 shows a square-structured secondary battery 4 as an example.
  • the housing may include a housing 41 and a cover 43 .
  • the housing 41 may include a bottom plate and side plates connected to the bottom plate, and the bottom plate and the side plates enclose a receiving cavity.
  • the housing 41 has an opening communicating with the accommodation cavity, and the cover plate 43 can cover the opening to close the accommodation cavity.
  • the positive electrode sheet, the negative electrode sheet and the separator film can be formed into the electrode assembly 42 through a winding process or a lamination process.
  • the electrode assembly 42 is packaged in the containing cavity.
  • the electrolyte soaks into the electrode assembly 42 .
  • the number of electrode assemblies 42 contained in the battery 4 can be one or more, and can be adjusted according to requirements.
  • This application also provides an electrical device, which includes the above-mentioned secondary battery.
  • the secondary battery may exist in the form of a battery cell or may be further assembled into a battery pack.
  • the battery pack 1 includes a battery box and one or more secondary batteries 4 provided in the battery box.
  • the battery box includes an upper box 2 and a lower box 3 .
  • the upper box 2 can be covered with the lower box 3 and form a closed space for the secondary battery 4 .
  • the plurality of secondary batteries 4 can be arranged in the battery box in any manner.
  • the above-mentioned secondary battery or the battery pack assembled therefrom can be used as a power source for an electrical device, or as an energy storage unit for an electrical device.
  • the above-mentioned electric devices may be, but are not limited to, mobile devices (such as mobile phones, laptops, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc.
  • mobile devices such as mobile phones, laptops, etc.
  • electric vehicles such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf golf carts, electric trucks, etc.
  • electric trains ships and satellites, energy storage systems, etc.
  • FIG. 5 shows an electrical device 5 as an example.
  • the electric device 5 is a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, or the like.
  • a battery pack may be used.
  • the power-consuming device may be a mobile phone, a tablet computer, a laptop computer, etc.
  • the device is usually required to be thin and light, and a battery can be used as a power source.
  • Modified negative electrode material C1 Disperse 10g of artificial graphite (C0) in 50g of ethyl methyl carbonate, stir for 1 hour, add 0.05g of dimethyldichlorosilane and stir for 0.5 hours, add 0.2g of tetraethyl silicate The ester was stirred for 16 hours, washed with ethyl methyl carbonate, filtered, and dried under vacuum at 60°C for 12 hours.
  • Infrared testing was conducted on the raw graphite and the modified negative electrode material. Comparison found that the modified negative electrode material showed Si-O bond signals at 1100 ⁇ 1000 -1 or 800cm -1 , and at 1290 ⁇ 1270cm -1 , 1280 ⁇ 1210cm -1 , or 1265cm -1 , or 829cm -1 , or 1250 ⁇ 1110cm -1 , or 1240cm -1 ⁇ 1160cm -1 , or 1130 ⁇ 1000cm -1 , or 1125 ⁇ 1110cm -1 , or 1050 ⁇ 1000cm
  • the signal of CO appears at -1
  • the signal of CH appears at 2890cm -1 or 1340cm -1 .
  • Modified negative electrode material C2 Disperse 10g of artificial graphite in 50g of ethylene glycol dimethyl ether, stir for 1 hour, add 0.05g of dimethyldichlorosilane and stir for 0.5 hours, add 0.2g of tetraethyl silicate , stir for 16 hours, wash with ethylene glycol dimethyl ether, filter, and dry under vacuum at 60°C for 12 hours.
  • Modified negative electrode material C3 Disperse 10g of artificial graphite in 50g of ethyl acetate, stir for 1 hour, add 0.05g of dimethyldichlorosilane and stir for 0.5 hours, add 0.2g of tetraethyl silicate, and stir for 16 After washing and filtering with ethyl acetate, the mixture was dried under vacuum at 60°C for 12 hours.
  • Modified negative electrode material C4 Disperse 10g of artificial graphite in 50g of ethanol, stir for 1 hour, add 0.05g of ammonia water and stir for 0.5 hours, add 0.2g of tetraethyl silicate, stir for 16 hours, wash with ethanol and filter. Dry under vacuum at 60°C for 12 hours.
  • Modified negative electrode material C5 Disperse 10g of artificial graphite in 50g of ethanol, stir for 1 hour, add 0.05g of hydrochloric acid and stir for 0.5 hours, add 0.2g of tetraethyl silicate, stir for 16 hours, wash with ethanol and filter. Dry under vacuum at 60°C for 12 hours.
  • Modified negative electrode material C6 Disperse 10g of artificial graphite in 50g of ethyl methyl carbonate and stir for 1 hour. Add 0.05g of dimethyldichlorosilane and stir for 0.5 hours. Add 0.2g of tetrapropyl silicate and stir. After washing and filtering with ethyl methyl carbonate for 16 hours, it was vacuum dried at 60°C for 12 hours.
  • Modified negative electrode material C7 Disperse 10g of artificial graphite (C0) in 50g of ethyl methyl carbonate, stir for 1 hour, add 0.05g of dimethyldichlorosilane and stir for 0.5 hours, add 0.2g of tetrahexyl silicate alkane, stirred for 16 hours, washed with ethyl methyl carbonate, filtered, and dried under vacuum at 60°C for 12 hours.
  • Modified negative electrode material C8 Disperse 10g of artificial graphite in 50g of ethyl methyl carbonate, stir for 1 hour, add 0.05g of dimethyldichlorosilane and stir for 0.5 hours, add 0.2g of tetraethyl carbonate, and stir for 16 hours, washed with ethyl methyl carbonate, filtered, and dried under vacuum at 60°C for 12 hours.
  • Modified negative electrode material C9 Disperse 10g of artificial graphite in 50g of ethyl methyl carbonate and stir for 1 hour. Add 0.05g of dimethyldichlorosilane and stir for 0.5 hours. Add 0.2g of tetraethyl pyrophosphate and stir. After washing and filtering with ethyl methyl carbonate for 16 hours, it was vacuum dried at 60°C for 12 hours.
  • Modified negative electrode material Si/C1 Disperse 10g of silicon carbon composite material (Betteri New Materials Group Co., Ltd. S500Si0) in 50g of ethyl methyl carbonate, stir for 1 hour, and add 0.01g of dimethyldichloride Stir the silane for 0.5 hours, add 0.2g of tetraethyl silicate, stir for 16 hours, wash with ethyl methyl carbonate, filter, and dry under vacuum at 60°C for 12 hours.
  • Modified negative electrode material Si/C2 Disperse 10g of silicon carbon composite material (Betteri New Materials Group Co., Ltd. S500) in 50g of ethyl methyl carbonate, stir for 1 hour, and add 0.05g of dimethyl dichloride Stir the silane for 0.5 hours, add 0.2g of tetraethyl silicate, stir for 16 hours, wash with ethyl methyl carbonate, filter, and dry under vacuum at 60°C for 12 hours.
  • Modified negative electrode material Si/C3 Disperse 10g of silicon carbon composite material (Betteri New Materials Group Co., Ltd. S500) in 50g of ethyl methyl carbonate, stir for 1 hour, and add 0.1g of dimethyl dichloride Stir the silane for 0.5 hours, add 0.2g of tetraethyl silicate, stir for 16 hours, wash with ethyl methyl carbonate, filter, and dry under vacuum at 60°C for 12 hours.
  • Modified negative electrode material Si/C4 Disperse 10g of silicon carbon composite material (Betteri New Materials Group Co., Ltd. S500) in 50g of ethyl methyl carbonate, stir for 1 hour, and add 0.5g of dimethyl dichloride Stir the silane for 0.5 hours, add 0.2g of tetraethyl silicate, stir for 16 hours, wash with ethyl methyl carbonate, filter, and dry under vacuum at 60°C for 12 hours.
  • Modified negative electrode material Si/C5 Disperse 10g of silicon carbon composite material (Betteri New Materials Group Co., Ltd. S500) in 50g of ethyl methyl carbonate, stir for 1 hour, and add 0.1g of dimethyl dichloride Stir the silane for 0.5 hours, add 0.05g of tetraethyl silicate, stir for 16 hours, wash with ethyl methyl carbonate, filter, and dry under vacuum at 60°C for 12 hours.
  • Modified negative electrode material Si6/C6 Disperse 10g of silicon carbon composite material (Betteri New Materials Group Co., Ltd. S500) in 50g of ethyl methyl carbonate, stir for 1 hour, and add 0.1g of dimethyl dichloride Stir the silane for 0.5 hours, add 0.1g of tetraethyl silicate, stir for 16 hours, wash with ethyl methyl carbonate, filter, and dry under vacuum at 60°C for 12 hours.
  • Modified negative electrode material Si/C7 Disperse 10g of silicon carbon composite material (Betteri New Materials Group Co., Ltd. S500) in 50g of ethyl methyl carbonate, stir for 1 hour, and add 0.1g of dimethyl dichloride Stir the silane for 0.5 hours, add 0.5g of tetraethyl silicate, stir for 16 hours, wash with ethyl methyl carbonate, filter, and dry under vacuum at 60°C for 12 hours.
  • Modified negative electrode material Si/C8 Disperse 10g of silicon carbon composite material (Betteri New Materials Group Co., Ltd. S500) in 50g of ethyl methyl carbonate, stir for 1 hour, and add 0.1g of dimethyl dichloride Stir the silane for 0.5 hours, add 1g of tetraethyl silicate, stir for 16 hours, wash with ethyl methyl carbonate, filter, and dry under vacuum at 60°C for 12 hours.
  • C1-C7 negative electrode sheet Combine the modified negative electrode material, conductive agent acetylene black, binder styrene-butadiene rubber (SBR), and thickener sodium carboxymethylcellulose (CMC) in a weight ratio of 90:4:4:2 Dissolve in solvent deionized water, mix evenly and prepare negative electrode slurry; then apply the negative electrode slurry evenly on the negative electrode current collector copper foil, dry it to obtain the negative electrode diaphragm, and then cold press and cut it to obtain the negative electrode electrode. piece.
  • SBR binder styrene-butadiene rubber
  • CMC thickener sodium carboxymethylcellulose
  • the modified negative electrode materials are respectively the above-mentioned modified negative electrode materials C1 to C7, and the prepared negative electrode sheets are correspondingly marked as C1 to C7.
  • LFP positive electrode Dissolve the positive active material lithium iron phosphate, the conductive agent acetylene black, and the binder polyvinylidene fluoride (PVDF) in the solvent N-methylpyrrolidone (NMP) at a weight ratio of 90:5:5. Stir and mix evenly to obtain the positive electrode slurry; then, the positive electrode slurry is evenly coated on the positive electrode current collector, and then dried, cold pressed, and cut to obtain the positive electrode sheet.
  • NMP N-methylpyrrolidone
  • EL0 electrolyte In an argon atmosphere glove box (H 2 O ⁇ 0.1ppm, O 2 ⁇ 0.1ppm), mix the organic solvent EC/EMC evenly according to the volume ratio of 3/7, and add 12.5wt% LiPF 6 lithium salt to dissolve In the organic solvent, add 1wt% PS, 0.5wt% DTD, 0.5wt% VC, and 2wt% FEC as additives, stir evenly, and obtain the corresponding electrolyte.
  • the negative electrode sheets C1 to C7 are respectively used as the above-mentioned negative electrode sheets, and the prepared lithium ion batteries are marked as C1 to C7 respectively.
  • Capacity retention rate (%) of a lithium-ion battery after 1000 cycles at 45°C C1000 (discharge capacity of the 1000th cycle/discharge capacity of the first cycle) ⁇ 100%.
  • Capacity retention rate (%) of lithium-ion batteries after storage at 60° C. for 300 days T300 (discharge capacity after storage for 300 days/discharge capacity at the first cycle) ⁇ 100%.
  • Embodiment 3 is basically the same as Embodiment 2, except that in the preparation of the negative electrode sheet in step (1), the modified negative electrode materials C1 to C7 are respectively replaced with Si/C1 to Si/C8, and the prepared negative electrode sheets correspond to The ground is recorded as Si/C1 ⁇ Si/C8.
  • the preparation of the positive electrode sheet is as follows: Dissolve the positive electrode active material LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM811), the conductive agent acetylene black, and the binder polyvinylidene fluoride (PVDF) in the solvent in a weight ratio of 90:5:5 N-methylpyrrolidone (NMP), stir thoroughly and mix evenly to obtain a positive electrode slurry; then the positive electrode slurry is evenly coated on the positive electrode current collector, and then dried, cold pressed, and cut to obtain positive electrode sheets.
  • NMP N-methylpyrrolidone
  • Example 2 The remaining steps are the same as in Example 2, and the prepared lithium-ion batteries are correspondingly marked as Si/C1 to Si/C8. Please see Table 2 for specific parameters and test results.
  • Examples 4 to 7 are basically the same as Example 3.
  • the negative active materials are Si/C1, Si/C2, Si/C3, and Si/C4 respectively;
  • the electrolytes are respectively EL1 electrolyte and EL2 electrolyte.
  • EL3 electrolyte, EL4 electrolyte the specific preparation process of the electrolyte is as follows:
  • EL1 electrolyte In an argon atmosphere glove box (H2O ⁇ 0.1ppm, O2 ⁇ 0.1ppm), mix the organic solvent EC/EMC evenly according to the volume ratio of 3/7, add 12.5wt% LiPF6 lithium salt and dissolve it in the organic solvent , add 1wt% PS, 0.5wt% DTD, 0.5wt% VC, 2wt% FEC, 1% tetraethyl silicate as additives, stir evenly, and obtain the corresponding electrolyte.
  • H2O ⁇ 0.1ppm, O2 ⁇ 0.1ppm In an argon atmosphere glove box (H2O ⁇ 0.1ppm, O2 ⁇ 0.1ppm), mix the organic solvent EC/EMC evenly according to the volume ratio of 3/7, add 12.5wt% LiPF6 lithium salt and dissolve it in the organic solvent , add 1wt% PS, 0.5wt% DTD, 0.5wt% VC, 2wt% FEC, 1% tetraethyl silicate as additives,
  • EL2 electrolyte In an argon atmosphere glove box (H 2 O ⁇ 0.1ppm, O 2 ⁇ 0.1ppm), mix the organic solvent EC/EMC evenly according to the volume ratio of 3/7, add 12.5wt% LiPF6 lithium salt and dissolve in In the organic solvent, add 1wt% PS, 0.5wt% DTD, 0.5wt% VC, 2wt% FEC, and 1% tetrapropyl silicate as additives, stir evenly, and obtain the corresponding electrolyte.
  • H 2 O ⁇ 0.1ppm, O 2 ⁇ 0.1ppm In an argon atmosphere glove box (H 2 O ⁇ 0.1ppm), mix the organic solvent EC/EMC evenly according to the volume ratio of 3/7, add 12.5wt% LiPF6 lithium salt and dissolve in In the organic solvent, add 1wt% PS, 0.5wt% DTD, 0.5wt% VC, 2wt% FEC, and 1% tetrapropyl silicate as additives, stir evenly, and
  • EL3 electrolyte In an argon atmosphere glove box (H 2 O ⁇ 0.1ppm, O 2 ⁇ 0.1ppm), mix the organic solvent EC/EMC evenly according to the volume ratio of 3/7, add 12.5wt% LiPF6 lithium salt and dissolve in In the organic solvent, add 1wt% PS, 0.5wt% DTD, 0.5wt% VC, 2wt% FEC, and 1% tetraethyl carbonate as additives, stir evenly, and obtain the corresponding electrolyte.
  • EL4 electrolyte In an argon atmosphere glove box (H 2 O ⁇ 0.1ppm, O 2 ⁇ 0.1ppm), mix the organic solvent EC/EMC evenly according to the volume ratio of 3/7, add 12.5wt% LiPF6 lithium salt and dissolve in In the organic solvent, add 1wt% PS (propanesulfolactone), 0.5wt% DTD (ethylene sulfate), 0.5wt% VC (vinylene carbonate), 2wt% FEC (chloroethylene carbonate), 1 % tetraethyl pyrophosphate as an additive, stir evenly to obtain the corresponding electrolyte.
  • PS propanesulfolactone
  • DTD ethylene sulfate
  • VC vinyl carbonate
  • FEC chloroethylene carbonate
  • 1 % tetraethyl pyrophosphate 1 % tetraethyl pyrophosphate
  • Comparative Example 1 is basically the same as Example 2, and the only difference is that in Comparative Example 1, the negative active material in the negative electrode sheet directly uses C0 (graphite).
  • Comparative Example 2 is basically the same as Example 2, except that in the preparation of the negative electrode sheet in Comparative Example 2, the modified negative electrode material C8 was used.
  • Comparative Example 3 is basically the same as Example 2, except that in the preparation of the negative electrode sheet in Comparative Example 2, the modified negative electrode material C9 was used.
  • Comparative Examples 4 to 7 are basically the same as Comparative Example 1, except that the electrolytes are EL1 electrolyte, EL2 electrolyte, EL3 electrolyte, and EL4 electrolyte respectively.
  • the specific preparation process of electrolytes EL1 to EL4 is the same as in the embodiment. 4 ⁇ 7.
  • Comparative Example 8 is basically the same as Example 3, except that the negative active material in the negative electrode sheet in Comparative Example 8 directly uses silicon-carbon composite material Si0 (ie, S500).
  • RO (m ⁇ ), R1000 (m ⁇ ), C1000 (%), and T300% respectively represent the initial internal resistance of the battery core, the internal resistance of the battery core after 1,000 cycles, and the capacity retention of the battery core after 1,000 cycles at 45°C. rate and capacity retention rate of batteries stored at 60°C for 300 days.
  • the internal resistance of the battery can be reduced and the cycle performance of the battery can be improved by using the modified negative electrode material of the present application.
  • the graphite negative electrode in Example 2 has been modified by silicate, which is beneficial to reducing impedance deterioration during cycling, improving interface stability, and thereby improving
  • the cycle capacity retention rate shows that the negative electrode material treated with silicate can improve the cycle stability of the battery core.
  • the graphite negative electrodes in Comparative Examples 2 and 3 were treated with non-silicate esters. From the cell performance feedback, it can be seen that there is almost no improvement in cell performance, while the experiments of Comparative Examples 4 to 7 proved that directly The introduction of silicate or silicate-like additives into the electrolyte has little improvement in the cycle performance of the battery.
  • the carbon-silicon negative electrode material modified by silicate in Example 3 has an improved effect on the cycle stability and capacity of the battery core. .

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Abstract

本申请提出一种改性负极材料及其制备方法、负极片、二次电池及用电装置。该改性负极材料包括负极活性基材及与所述负极活性基材通过氧原子连接的硅酸酯基，所述硅酸酯基的结构如式(1)所示，其中，各R1分别独立地选自取代或未取代的碳原子数为1～10的烷基、或取代或未取代的碳原子数为1～10的烯烃基；*代表连接位点。

Description

改性负极材料及其制备方法、负极片、二次电池及用电装置 技术领域
本申请涉及电池领域，具体涉及一种改性负极材料及其制备方法、负极片、二次电池及用电装置。
背景技术
二次电池因其清洁和可再生的特点得到日益广泛的应用，具有能量密度高、自放电小、循环性能优越等优点。
二次电池主要依靠活性离子在正极和负极之间移动来产生电能，充电时，活性离子从正极脱嵌，经过电解液嵌入负极，放电时则相反。然而，二次电池在充放电过程中，锂离子等活性离子的嵌入和脱出会引起负极片的膨胀和收缩，对负极材料结构造成破坏，且在循环充放电过程中，电解液溶剂的共嵌、有机溶剂的还原以及大电流下的产气，均致使负极活性材料剥落，导致其界面不稳定性增加，造成负极活性物质损失及破坏固体电解质界面(SEI)膜，从而降低了二次电池的循环寿命。
随着需求的提升，传统的二次电池的循环性能越来越难以满足人们的需求，有待进一步改进。
发明内容
鉴于上述问题，本申请提供一种改性负极材料及其制备方法、负极片、二次电池及用电装置，旨在提高二次电池的循环性能。
为了实现上述目的，本申请的第一方面提供了一种改性负极材料，所述改性负极材料包括负极活性基材及与所述负极活性基材通过氧原子连接的硅酸酯基，所述硅酸酯基的结构如式(1)所示：
Figure PCTCN2022112711-appb-000001
其中，各R 1分别独立地选自取代或未取代的碳原子数为1～10的烷基、或取代或未取代的碳原子数为1～10的烯基；
*代表连接位点。
上述改性负极材料中，采用在负极活性基材表面通过氧原子连接硅酸酯基，这种硅酸酯的结构和原硅酸的结构类似，在充放电过程中可以发生分解形成硅酸，进而与电解液中的阳离子生成硅酸盐，一方面，硅酸盐具有碱性，可以清除电解液中产生的酸性物质，抑制HF等对界面结构的破坏，另一方面，硅酸盐具有一定的粘性，其可以负载在负极片表面，起到稳定作用，可以提高负极片的界面稳定性，由此，可以降低二次电池的电阻，提高二次电池的循环性能。
在本申请任意实施方式中，各R 1分别独立地选自取代或未取代的碳原子数为1～6的烷基。
可选地，各R 1分别独立地选自取代或未取代的碳原子数为1～4的烷基。
通过调节R 1的碳原子数，从而进一步降低R 1的位阻，可以进一步提高二次电池的循环性能。
在本申请任意实施方式中，各R 1分别独立地选自未取代的碳原子数为1～4的链烷基或被卤素取代的碳原子数为1～4的链烷基。
在本申请任意实施方式中，各R 1分别独立地选自甲基、乙基、正丙基、异丙基、正丁基、异丁基及其卤代物中的任意一种。
在本申请任意实施方式中，所述硅酸酯基满足如下(a)～(b)中至少一个条件：
(a)所述硅酸酯基在所述改性负极材料中的占比为0.005wt％～5wt％；
(b)所述硅酸酯基负载在所述负极活性基材表面形成包覆层。
在本申请任意实施方式中，所述包覆层的厚度为1nm～20nm。
在本申请任意实施方式中，所述负极活性基材包括碳基材和硅基材中的至少一种。
本申请的第二方面，提供了一种改性负极材料的制备方法，包括如下步骤：
将负极活性基材与式(2)化合物进行酯交换反应，制备所述改性负极材料；
Figure PCTCN2022112711-appb-000002
其中，所述负极活性基材的表面含有羟基；式(2)中R 1与第一方面中R 1相同。
通过将式(2)化合物与负极活性基材上的羟基进行酯交换反应，获得上述改性负极材料。
在本申请任意实施方式中，所述酯交换反应的温度为50℃～80℃，时间为6h～24h。
在本申请任意实施方式中，所述式(2)化合物与所述负极活性基材的质量比为(0.05～1)：10。
在本申请任意实施方式中，所述酯交换反应在酯交换催化剂的作用下进行，所述酯交换催化剂满足如下(c)～(d)中至少一个条件：
(c)所述酯交换催化剂包括碱性催化剂、酸性催化剂及有机硅烷中的至少一种；
可选地，所述酯交换催化剂包括无机碱、有机碱、无机酸、有机酸及有机氯硅烷中的至少一种；
可选地，所述酯交换催化剂包括氢氧化钠、氢氧化钾、盐酸、硫酸、氨水及二甲基二氯硅烷中的至少一种；
(d)所述酯交换催化剂与所述负极活性基材的质量比为(0.01～0.5)：10。
在本申请任意实施方式中，所述酯交换反应在有机溶剂中进行，所述有机溶剂满足如下(e)～(f)中至少一个条件：
(e)所述有机溶剂包括碳酸酯类溶剂、羧酸酯类溶剂、醇类溶剂和醚类溶剂中的至少一种；
可选地，所述有机溶剂包括碳酸二甲酯、碳酸甲乙酯、乙醇和乙二醇二甲醚中的至少一种；
(f)所述有机溶剂与所述负极活性基材的质量比为(10～300)：10。
本申请的第三方面，提供了一种负极片，所述负极片包括集流体及设于所述集流体表面的负极活性层，所述负极活性层的组分包括第一方面的 改性负极材料或第二方面的改性负极材料的制备方法制备得到的改性负极材料。
在本申请任意实施方式中，所述改性负极材料在所述负极活性层中的质量占比为70％～99.5％。
本申请的第四方面提供了一种二次电池，所述二次电池包含本申请第三方面的负极片。
在本申请任意实施方式中，所述负极片中的所述负极活性层表面负载有硅酸盐，所述硅酸盐中的硅酸基团源自于所述硅酸酯基的分解。
本申请的第五方面提供一种用电装置，所述用电装置包括本申请第四方面的二次电池。
上述说明仅是本申请技术方案的概述，为了能够更清楚了解本申请的技术手段，而可依照说明书的内容予以实施，并且为了让本申请的上述和其它目的、特征和优点能够更明显易懂，以下特举本申请的具体实施方式。
附图说明
通过阅读对下文优选实施方式的详细描述，各种其他的优点和益处对于本领域普通技术人员将变得清楚明了。附图仅用于示出优选实施方式的目的，而并不认为是对本申请的限制。而且在全部附图中，用相同的附图标号表示相同的部件。在附图中：
图1是二次电池的一实施方式的示意图。
图2是图1的分解图。
图3是电池包的一实施方式的示意图。
图4是图3的分解图。
图5是二次电池用作电源的用电装置的一实施方式的示意图。
附图标记说明：
1、电池包；2、上箱体；3、下箱体；4、二次电池；41、壳体；42、电极组件；43、盖板；5、用电装置。
具体实施方式
下面将结合附图对本申请技术方案的实施例进行详细的描述。以下实 施例仅用于更加清楚地说明本申请的技术方案，因此只作为示例，而不能以此来限制本申请的保护范围。
除非另有定义，本文所使用的所有的技术和科学术语与属于本申请的技术领域的技术人员通常理解的含义相同；本文中所使用的术语只是为了描述具体的实施例的目的，不是旨在于限制本申请；本申请的说明书和权利要求书及上述附图说明中的术语“包括”和“具有”以及它们的任何变形，意图在于覆盖不排他的包含。
在本申请实施例的描述中，技术术语“第一”“第二”等仅用于区别不同对象，而不能理解为指示或暗示相对重要性或者隐含指明所指示的技术特征的数量、特定顺序或主次关系。在本申请实施例的描述中，“多个”的含义是两个以上，除非另有明确具体的限定。
在本文中提及“实施例”意味着，结合实施例描述的特定特征、结构或特性可以包含在本申请的至少一个实施例中。在说明书中的各个位置出现该短语并不一定均是指相同的实施例，也不是与其它实施例互斥的独立的或备选的实施例。本领域技术人员显式地和隐式地理解的是，本文所描述的实施例可以与其它实施例相结合。
在本申请实施例的描述中，术语“和/或”仅仅是一种描述关联对象的关联关系，表示可以存在三种关系，例如A和/或B，可以表示：单独存在A，同时存在A和B，单独存在B这三种情况。另外，本文中字符“/”，一般表示前后关联对象是一种“或”的关系。
在本申请实施例的描述中，术语“多个”指的是两个以上(包括两个)，同理，“多组”指的是两组以上(包括两组)，“多片”指的是两片以上(包括两片)。
在本申请实施例的描述中，技术术语“中心”“纵向”“横向”“长度”“宽度”“厚度”“上”“下”“前”“后”“左”“右”“竖直”“水平”“顶”“底”“内”“外”“顺时针”“逆时针”“轴向”“径向”“周向”等指示的方位或位置关系为基于附图所示的方位或位置关系，仅是为了便于描述本申请实施例和简化描述，而不是指示或暗示所指的装置或元件必须具有特定的方位、以特定的方位构造和操作，因此不能理解为对本申请实施例的限制。
在本申请实施例的描述中，除非另有明确的规定和限定，技术术语“安 装”“相连”“连接”“固定”等术语应做广义理解，例如，可以是固定连接，也可以是可拆卸连接，或成一体；也可以是机械连接，也可以是电连接；可以是直接相连，也可以通过中间媒介间接相连，可以是两个元件内部的连通或两个元件的相互作用关系。对于本领域的普通技术人员而言，可以根据具体情况理解上述术语在本申请实施例中的具体含义。
综上背景技术所述，负极片界面的不稳定性，限制了二次电池的循环性能的提升。传统技术中，常通过在电解液添加功能剂，使其在充放电过程中在负极界面原位形成包覆膜，以提高界面稳定性，或是直接对负极材料进行表面包覆处理，以提高界面稳定性。
然而，本申请的技术人员在实际生产过程中研究发现：通过在电解液添加功能剂原位形成包覆膜的方法中，形成的界面内层的无机组分中多是晶体结构的氧化物或盐，这种无机层在脱/嵌锂的体积变化过程中很容易破裂，导致活性组分和电解液直接接触，引起电解液和活性锂的过度消耗，反而会恶化电芯性能；而直接对负极材料进行表面包覆处理时，形成的界面与负极的结合不稳定，尤其是在高SOC状态下的稳定性仍存在很大问题，无法满足人们对二次电池的循环性能越来高的需求。
基于此，本申请的技术人员在经过大量实验探究之后，创造性地提出对负极材料进行化学改性，通过化学键与功能基团连接，并选择特定的功能基团，使其能在充放电过程中分解形成具有粘性的物质，负载在负极界面上，以提高界面稳定性，进而提高二次电池的循环性能。
本申请一实施方式，提供了一种改性负极材料，该改性负极材料包括负极活性基材及与所述负极活性基材通过氧原子连接的硅酸酯基，所硅酸酯基的结构如式(1)所示：
Figure PCTCN2022112711-appb-000003
其中，各R 1分别独立地选自取代或未取代的碳原子数为1～10的烷基、或取代或未取代的碳原子数为1～10的烯基；
*代表连接位点。
上述改性负极材料中，采用在负极活性基材表面通过氧原子连接硅酸酯基，这种硅酸酯的结构和原硅酸的结构类似，在充放电过程中可以发生分解，进而生成硅酸盐，一方面，硅酸盐具有碱性，可以清除电解液中产生的酸性物质，抑制HF等对界面结构的破坏，另一方面，硅酸盐具有一定的粘性，其可以负载在负极片表面，起到稳定作用，可以提高负极片的界面稳定性，由此，可以降低二次电池的电阻，提高二次电池的循环性能。
上述改性负极材料的结构示意如下：
(R 1O) 3-Si-O-M
M代表负极活性基材。
上述“碳原子数为1～10”中，碳原子数取值包括该范围的最小值及最大值，以及这种最小值与最大值之间的每一个整数值，具体示例包括但不限于实施例中的点值以及：1、2、3、4、5、6、7、8、9、10。
在本申请任意实施方式中，各R 1分别独立地选自未取代的碳原子数为1～10的烷基或被卤素取代的碳原子数为1～10的烷基。
上述被卤素取代的碳原子数为1～10的烷基中是卤素原子的个数没有特别的限定。
可选地，被卤素取代的碳原子数为1～10的烷基中至少含有一个卤素原子。
可选地，被卤素取代的碳原子数为1～10的烷基中至少含有两个卤素原子。
可选地，被卤素取代的碳原子数为1～10的烷基中至少含有三个卤素原子。
可选地，卤素包括氟、氯、溴、碘中的至少一种。
在本申请任意实施方式中，各R 1分别独立地选自未取代的碳原子数为1～10的链烷基或被卤素取代的碳原子数为1～10的链烷基。
在本申请任意实施方式中，各R 1分别独立地选自取代或未取代的碳原子数为1～6的烷基。
在本申请任意实施方式中，各R 1分别独立地选自取代或未取代的碳原子数为1～4的烷基。
通过调节R 1的碳原子数，从而进一步降低R 1的位阻，可以进一步提高二次电池的循环性能。
在本申请任意实施方式中，各R 1分别独立地选自未取代的碳原子数为1～4的链烷基或被卤素取代的碳原子数为1～4的链烷基。
在本申请任意实施方式中，各R 1分别独立地选自未取代的碳原子数为1～4的直链烷基或被卤素取代的碳原子数为1～4的直链烷基。
在本申请任意实施方式中，各R 1分别独立地选自甲基、乙基、正丙基、异丙基、正丁基、异丁基及其卤代物中的任意一种。
可选地，各R 1分别独立地选自甲基、乙基、正丙基、异丙基、正丁基、异丁基、氯甲基、二氯甲基、氯乙基、二氯乙基中的任意一种。
在本申请任意实施方式中，上述硅酸酯基在所述改性负极材料中的占比为0.005wt％～5wt％。
在本申请任意实施方式中，上述硅酸酯基负载在负极活性基材表面形成包覆层。
上述硅酸酯基负载在负极活性基材表面后，聚集形成包覆层包覆负极活性基材。
在本申请任意实施方式中，上述包覆层的厚度为1nm～20nm。
在本申请任意实施方式中，上述负极活性基材包括碳基材和硅基材中的至少一种。
可选地，上述负极活性基材可选自但不限于：石墨、软碳、硬碳、中间相碳微球、碳纤维、碳纳米管、单质硅、硅氧化合物、硅碳复合物、或这些材料添加过渡金属或非过渡金属得到的复合物中的一种或几种。
可选地，上述负极活性基材选自石墨、单质硅、硅氧化合物、硅碳复合物中的至少一种。
本发明一实施方式，提供了一种改性负极材料的制备方法，包括如下步骤S10。
步骤S10、将负极活性基材与式(2)化合物进行酯交换反应，制备改性负极材料；
Figure PCTCN2022112711-appb-000004
其中，负极活性基材的表面含有羟基；式(2)中R 1与第一方面中R 1相同。
通过将式(2)化合物与负极活性基材上的羟基进行酯交换反应，获得上述改性负极材料。
具体的反应路线如下：
(R 1O) 3-Si-OR 1+M-OH→(R 1O) 3-Si-O-M+R 1OH
其中，M代表负极活性基材，负极活性基材的选择同上所述，在此不再赘述。
上述负极活性基材可采用本领域常规的未活化处理的负极活性基材，也可以是经过活化处理在表面形成羟基的负极活性基材。可理解：本领域常用的负极活性基材，包括硅基负极活性材料、碳基负极活性材料，其表面本身就分布有丰富的羟基，式(2)化合物与常规的负极活性基材上的羟基进行酯交换反应，就可获得上述改性负极材料，也可将常规负极活性基材作活化处理改性，进一步在表面形成更丰富的羟基，再与式(2)化合物反应。
在本申请任意实施方式中，上述酯交换反应的温度为50℃～80℃，时间为6h～24h。
在本申请任意实施方式中，上述式(2)化合物与上述负极活性基材的质量比为(0.05～1)：10。
通过调控酯交换反应的反应条件极其原料配比，以尽可能使负极活性基材表面的羟基均与式(2)化合物反应。
在本申请任意实施方式中，上述酯交换反应在酯交换催化剂的作用下进行。
可选地，上述酯交换催化剂包括碱性催化剂、酸性催化剂及有机硅烷中的至少一种。
可选地，上述酯交换催化剂包括无机碱、有机碱、无机酸、有机酸及有机氯硅烷中的至少一种；
可选地，上述酯交换催化剂包括氢氧化钠、氢氧化钾、盐酸、硫酸、氨水及二甲基二氯硅烷中的至少一种。
在本申请任意实施方式中，上述酯交换催化剂与上述负极活性基材的质量比为(0.01～0.5)：10。
在本申请任意实施方式中，上述酯交换反应在有机溶剂中进行。
可选地，上述有机溶剂包括碳酸酯类溶剂、羧酸酯类溶剂、醇类溶剂和醚类溶剂中的至少一种。
可选地，上述有机溶剂包括碳酸二甲酯、碳酸甲乙酯、乙醇和乙二醇二甲醚中的至少一种。
在本申请任意实施方式中，上述有机溶剂与在本申请任意实施方式中，上述负极活性基材的质量比为(10～300)：10。
式(2)中R 1的选择同上，在此不再赘述。
可选地，式(2)化合物选自硅酸四甲酯，硅酸四丁酯、硅酸四乙酯，硅酸四丙酯、硅酸四己酯中的至少一种。
[负极片]
本申请一实施方式还提供一种负极片，该负极片包括集流体及设于集流体表面的负极活性层，负极活性层的组分包括上述改性负极材料或上述改性负极材料的制备方法制备得到的改性负极材料。
该极片的阻抗低，在充放电过程中能保持稳定的界面，进而能提高二次电池的循环性能。
在本申请任意实施方式中，上述改性负极材料在负极活性层中的质量占比为70％～99.5％。
在本申请任意实施方式中，上述负极活性层的组分还包括负极导电剂及负极粘结剂。
在本申请任意实施方式中，上述负极导电剂可以采用本领域常用的导电材料，包括但不限于：石墨、碳纳米管、纳米纤维、炭黑和石墨烯中的至少一种。具体地，可选自SP、KS-6，乙炔黑、有支链结构的科琴黑ECP，SFG-6，气相生长碳纤维VGCF，碳纳米管CNTs和石墨烯及其复合导电剂中的至少一种。
基于负极活性层的总重量计，负极导电剂在负极活性层中的重量比为0～20wt％。
上述负极粘结剂可采用本领域常用的粘结剂，可选自丁苯橡胶(SBR)、聚丙烯酸(PAA)、聚丙烯酸钠(PAAS)、聚丙烯酰胺(PAM)、聚乙烯醇(PVA)、海藻酸钠(SA)、聚甲基丙烯酸(PMAA)及羧甲基壳聚 糖(CMCS)中的至少一种。
基于负极活性层的总重量计，负极粘结剂在负极活性层中的重量比为0～30wt％。
在本申请任意实施方式中，负极活性层还可选地包括其他助剂，例如增稠剂，如羧甲基纤维素钠(CMC-Na)等。基于负极活性层的总重量计，其他助剂在负极活性层中的重量比为0～15wt％。
在本申请任意实施方式中，负极片中的集流体可采用金属箔片或复合集流体。例如，作为金属箔片，可采用铜箔。复合集流体可包括高分子材料基层和形成于高分子材料基层至少一个表面上的金属层。复合集流体可通过将金属材料(铝、铝合金、镍、镍合金、钛、钛合金、银及银合金等)形成在高分子材料基材(如聚丙烯(PP)、聚对苯二甲酸乙二醇酯(PET)、聚对苯二甲酸丁二醇酯(PBT)、聚苯乙烯(PS)、聚乙烯(PE)等的基材)上而形成。
在本申请任意实施方式中，可以通过以下方式制备负极片：将上述用于制备负极片的组分，例如改性负极活性材料、导电剂、粘结剂和任意其他组分分散于溶剂(例如去离子水)中，形成负极浆料；将负极浆料涂覆在负极集流体上，经烘干、冷压等工序后，即可得到负极片。其中所述负极浆料固含量为30wt％～70wt％，室温下的粘度调整到2000mPa·s～10000mPa·s；将所得到的负极浆料涂覆在负极集流体上，经过干燥工序，冷压例如对辊，得到负极片。负极粉末涂布单位面密度为75mg/m 2～220mg/m 2，负极片压实密度1.2g/m 3～2.0g/m 3。
本申请一实施方式提供了一种二次电池，包含上述负极片。
该二次电池的循环性能优异。
可选地，上述二次电池可以是钠离子电池、锂离子电池、钾离子电池。
在本申请任意实施方式中，上述二次电池还包括正极片、电解液及隔离膜。
下面对正极片、电解液隔离膜进行举例说明，但不限于如下范围。
[正极片]
正极片包括集流体及设于集流体表面的正极活性层，正极活性层的组分包括正极活性材料。
作为示例，正极片中的集流体具有在其自身厚度方向相对的两个表面，正极活性材料层设置在正极集流体相对的两个表面的其中任意一者或两者上。
在本申请任意实施方式中，正极片中的集流体可采用金属箔片或复合集流体。例如，作为金属箔片，可采用铝箔。复合集流体可包括高分子材料基层和形成于高分子材料基层至少一个表面上的金属层。复合集流体可通过将金属材料(铝、铝合金、镍、镍合金、钛、钛合金、银及银合金等)形成在高分子材料基材(如聚丙烯(PP)、聚对苯二甲酸乙二醇酯(PET)、聚对苯二甲酸丁二醇酯(PBT)、聚苯乙烯(PS)、聚乙烯(PE)等的基材)上而形成。
上述正极活性材料可采用本申请中的常用的正极活性材料，例如锂离子正极活性材料或钠离子正极活性材料。
进一步地，作为示例，锂离子活性材料可包括以下材料中的至少一种：橄榄石结构的含锂磷酸盐、锂过渡金属氧化物及其各自的改性化合物。但本申请并不限定于这些材料，还可以使用其他可被用作电池正极活性材料的传统材料。这些正极活性材料可以仅单独使用一种，也可以将两种以上组合使用。其中，锂过渡金属氧化物的示例可包括但不限于锂钴氧化物(如LiCoO 2)、锂镍氧化物(如LiNiO 2)、锂锰氧化物(如LiMnO 2、LiMn 2O 4)、锂镍钴氧化物、锂锰钴氧化物、锂镍锰氧化物、锂镍钴锰氧化物(如LiNi 1/3Co 1/3Mn 1/3O 2(也可以简称为NCM333)、LiNi 0.5Co 0.2Mn 0.3O 2(也可以简称为NCM523)、LiNi 0.5Co 0.25Mn 0.25O 2(也可以简称为NCM211)、LiNi 0.6Co 0.2Mn 0.2O 2(也可以简称为NCM622)、LiNi 0.8Co 0.1Mn 0.1O 2(也可以简称为NCM811)、锂镍钴铝氧化物(如LiNi 0.85Co 0.15Al 0.05O 2)及其改性化合物等中的至少一种。橄榄石结构的含锂磷酸盐的示例可包括但不限于磷酸铁锂(如LiFePO 4(也可以简称为LFP))磷酸锰锂(如LiMnPO 4)、磷酸锰铁锂中的至少一种。
在本申请任意实施方式中，锂离子活性材料的分子式为：LiFe xMn (1-x)PO 4，x取0～1任一数。
可理解，当x取0时，LiFe xMn (1-x)PO 4即为LiMnPO 4磷酸锰锂，当x取1时，LiFePO 4即为LiFePO 4磷酸铁锂(LFP)。
作为示例，钠离子活性材料可包括以下材料中的至少一种：钠过渡金属氧化物、聚阴离子型化合物和普鲁士蓝类化合物中的至少一种。但本申请并不限定于这些材料，还可以使用其他可被用作钠离子电池正极活性材料的传统公知的材料。
作为本申请可选的技术方案，钠过渡金属氧化物中，过渡金属至少包括Mn、Fe、Ni、Co、Cr、Cu、Ti、Zn、V、Zr及Ce中的至少一种。钠过渡金属氧化物例如为Na xMO 2，其中M至少包括Ti、V、Mn、Co、Ni、Fe、Cr及Cu中的一种或几种，0＜x≤1。
作为本申请可选的技术方案，聚阴离子型化合物可以是具有钠离子、过渡金属离子及四面体型(YO 4) n-阴离子单元的一类化合物。过渡金属至少包括Mn、Fe、Ni、Co、Cr、Cu、Ti、Zn、V、Zr及Ce中的至少一种；Y至少包括P、S及Si中的至少一种；n表示(YO 4) n-的价态。
聚阴离子型化合物还可以是具有钠离子、过渡金属离子、四面体型(YO 4) n-阴离子单元及卤素阴离子的一类化合物。过渡金属至少包括Mn、Fe、Ni、Co、Cr、Cu、Ti、Zn、V、Zr及Ce中的至少一种；Y至少包括P、S及Si中的至少一种，n表示(YO 4) n-的价态；卤素可以是F、Cl及Br中的至少一种。
聚阴离子型化合物还可以是具有钠离子、四面体型(YO 4) n-阴离子单元、多面体单元(ZO y) m+及可选的卤素阴离子的一类化合物。Y至少包括P、S及Si中的至少一种，n表示(YO 4) n-的价态；Z表示过渡金属，至少包括Mn、Fe、Ni、Co、Cr、Cu、Ti、Zn、V、Zr及Ce中的至少一种，m表示(ZO y) m+的价态；卤素可以是F、Cl及Br中的至少一种。
聚阴离子型化合物例如是NaFePO 4、Na 3V 2(PO 4) 3(磷酸钒钠，简称NVP)、Na 4Fe 3(PO 4) 2(P 2O 7)、NaM’PO 4F(M’为V、Fe、Mn及Ni中的一种或几种)及Na 3(VO y) 2(PO 4) 2F 3-2y(0≤y≤1)中的至少一种。
普鲁士蓝类化合物可以是具有钠离子、过渡金属离子及氰根离子(CN -) 的一类化合物。过渡金属至少包括Mn、Fe、Ni、Co、Cr、Cu、Ti、Zn、V、Zr及Ce中的至少一种。普鲁士蓝类化合物例如为Na aMe bMe’ c(CN) 6，其中Me及Me’各自独立地至少包括Ni、Cu、Fe、Mn、Co及Zn中的至少一种，0＜a≤2，0＜b＜1，0＜c＜1。
基于正极活性层的总重量计，正极活性材料在正极活性层中的重量比为80wt％～100wt％。
在本申请任意实施方式中，正极活性层的组分还包括正极导电剂和正极粘结剂。
上述正极导电剂可以采用本领域常用的导电剂，包括但不限于：石墨、碳纳米管、纳米纤维、炭黑和石墨烯中的至少一种。具体地，可选自SP、KS-6，乙炔黑、有支链结构的科琴黑ECP，SFG-6，气相生长碳纤维VGCF，碳纳米管CNTs和石墨烯及其复合导电剂中的至少一种。
基于正极活性层的总重量计，正极导电剂在正极活性层中的重量比为0～20wt％。
在本申请任意实施方式中，上述正极粘结剂的粘结剂可以是聚偏氟乙烯(PVDF)、聚四氟乙烯(PTFE)、偏氟乙烯-四氟乙烯-丙烯三元共聚物、偏氟乙烯-六氟丙烯-四氟乙烯三元共聚物、四氟乙烯-六氟丙烯共聚物、氢化丁腈橡胶、丁苯橡胶(SBR)、聚丙烯酸(PAA)、聚丙烯酸钠(PAAS)、聚丙烯酰胺(PAM)、聚乙烯醇(PVA)、海藻酸钠(SA)、聚甲基丙烯酸(PMAA)及羧甲基壳聚糖(CMCS)及含氟丙烯酸酯树脂中的至少一种。
基于正极活性层的总重量计，正极粘结剂在正极活性层中的重量比为0～30wt％。
在本申请任意实施方式中，可以通过以下方式制备正极极片：将上述用于制备正极片的组分分散于溶剂(例如N-甲基吡咯烷酮)中，形成正极浆料；将正极浆料涂覆在集流体上，经烘干、冷压等工序后，即可得到正极片。正极浆料固含量为40wt％～80wt％，室温下的粘度调整到5000mPa·s～25000mPa·s，将正极浆料涂覆在正极集流体的表面，烘干后经过冷轧机 冷压后形成正极极片；正极粉末涂布单位面密度为150～350mg/m 2，正极极片压实密度为3.0～3.6g/cm 3，可选为3.3～3.5g/cm 3。压实密度的计算公式为：
压实密度＝涂布面密度/(挤压后极片厚度-集流体厚度)。
[电解液]
电解液包括电解质盐及溶剂
在一些实施方式中，电解质盐可选自本领域常用的电解质盐，包括锂离子电解质盐和钠离子电解质盐。
作为示例，锂离子电解质盐选自：六氟磷酸锂(LiPF 6)、四氟硼酸锂(LiBF 4)、高氯酸锂(LiClO 4)、六氟砷酸锂(LiAsF 6)、双氟磺酰亚胺锂(LiFSI)、双三氟甲磺酰亚胺锂(LiTFSI)、三氟甲磺酸锂(LiTFS)、二氟草酸硼酸锂(LiDFOB)、二草酸硼酸锂(LiBOB)、二氟磷酸锂(LiPO 2F 2)、二氟二草酸磷酸锂(LiDFOP)、Li(FSO 2) 2N、LiCF 3SO 3及四氟草酸磷酸锂(LiTFOP)中的一种或几种。
在本申请任意实施例中，上述负极片中的负极活性层表面负载有硅酸盐，硅酸盐中的硅酸基团源自于硅酸酯基的分解。
在二次电池的充方电过程中，负极活性基材表面连接的硅酸酯基可以发生分解，进而生成硅酸盐，一方面，硅酸盐具有碱性，部分硅酸锂盐与酸性物质结合，可以清除电解液中产生的酸性物质，抑制HF等对界面结构的破坏，另一方面，硅酸盐具有一定的粘性，部分硅酸盐可以负载在负极片表面，起到稳定作用，可以提高负极片的界面稳定性，由此，可以降低二次电池的电阻，提高二次电池的循环性能。
上述硅酸盐中的阳离子基团源自于电解液的组分，进一步地，源自于电解质盐中的阳离子，例如电解质盐为钠离子电解质盐时，形成钠硅酸盐，电解质盐为钾离子电解质盐时，形成钾硅酸盐，电解质盐为锂离子电解质盐时，形成锂硅酸盐。
可选地，上述硅酸盐可以是上述锂硅酸盐、也可以是钠硅酸盐或钾硅酸盐，锂硅酸盐、钠硅酸盐或钾硅酸盐均有类似于“水玻璃”的性质，具有一定的粘性，例如硅酸钠、Li 4SiO 4、Li 2SiO 3和Li 2SiO 5等。
在本申请任意实施方式中，溶剂可选自氟代碳酸乙烯酯(FEC)、碳酸 亚乙酯(EC)、碳酸亚丙基酯(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)、碳酸亚丁酯(BC)、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)及二乙砜(ESE)中的一种或几种。
在本申请任意实施方式中，电解质盐的浓度通常为0.5mol/L～15mol/L。
在本申请任意实施方式中，所述电解液还可选地包括添加剂。例如添加剂可以包括负极成膜添加剂、正极成膜添加剂，还可以包括能够改善电池某些性能的添加剂，例如改善电池过充性能的添加剂、改善电池高温或低温性能的添加剂等。
[隔离膜]
隔离膜设于正极片和负极片之间。
本申请对隔离膜的种类没有特别的限制，可以选用任意公知的具有良好的化学稳定性和机械稳定性的多孔结构隔离膜。
在其中一些实施方式中，隔离膜的材质可选自玻璃纤维、无纺布、聚乙烯、聚丙烯及聚偏二氟乙烯中的至少一种。隔离膜可以是单层薄膜，也可以是多层复合薄膜，没有特别限制。在隔离膜为多层复合薄膜时，各层的材料可以相同或不同，没有特别限制。
上述二次电池还包括外壳，用于包装正极片、负极片、隔离膜及电解液。
在其中一些实施方式中，上述外壳的可以是硬壳，例如硬塑料壳、铝壳、钢壳等。也可以是软包，例如袋式软包。软包的材质可以是塑料，作为塑料，可列举出聚丙烯、聚对苯二甲酸丁二醇酯以及聚丁二酸丁二醇酯等。
本申请对二次电池的形状没有特别的限制，其可以是圆柱形、方形或其他任意的形状。例如，图1是作为一个示例的方形结构的二次电池4。
在一些实施例中，参照图2，外壳可包括壳体41和盖板43。其中，壳体41可包括底板和连接于底板上的侧板，底板和侧板围合形成容纳腔。壳体41具有与容纳腔连通的开口，盖板43能够盖设于所述开口，以封闭所述容纳腔。
正极片、负极片和隔离膜可经卷绕工艺或叠片工艺形成电极组件42。电极组件42封装于容纳腔。电解液浸润于电极组件42中。电池4所含电极组件42的数量可以为一个或多个，可根据需求来调节。
本申请还提供一种用电装置，该用电装置包括上述的二次电池。
进一步地，在上述用电装置中，二次电池可以电池单体的形式存在，也可以进一步组装成电池包的形式存在。
图3和图4是作为一个示例的电池包1。在电池包1中包括电池箱和设置于电池箱中的一个或多个二次电池4。电池箱包括上箱体2和下箱体3，上箱体2能够盖设于下箱体3，并形成用于二次电池4的封闭空间。
多个二次电池4可以按照任意的方式排布于电池箱中。
上述二次电池或其组装成的电池包可以用作用电装置的电源，也可以作为用电装置的能量存储单元。
上述用电装置可以但不限于是移动设备(例如手机、笔记本电脑等)、电动车辆(例如纯电动车、混合动力电动车、插电式混合动力电动车、电动自行车、电动踏板车、电动高尔夫球车、电动卡车等)、电气列车、船舶及卫星、储能系统等。
图5是作为一个示例的用电装置5。该用电装置5为纯电动车、混合动力电动车、或插电式混合动力电动车等。为了满足该用电装置5对二次电池的高功率和高能量密度的需求，可以采用电池包形式。
作为另一个示例的用电装置可以是手机、平板电脑、笔记本电脑等。该装置通常要求轻薄化，可以采用电池作为电源。
下面将结合具体的实施例对本发明进行了说明，但本发明并不局限于下述实施例，应当理解，所附权利要求概括了本发明的范围，在本发明构思的引导下本领域的技术人员应意识到，对本发明的各实施例所进行的一 定的改变，都将被本发明的权利要求书的精神和范围所覆盖。
以下为具体实施例。
具体实施例
实施例1
(1)改性负极材料的制备：制备各类改性负极材料，具体步骤如下：
改性负极材料C1：取10g的人造石墨(C0)分散在50g的碳酸甲乙酯中，搅拌1小时，加入0.05g的二甲基二氯硅烷搅拌0.5小时，加入0.2g的硅酸四乙酯，搅拌16小时用碳酸甲乙酯洗涤过滤后，在60℃的真空干燥12小时。
对原料石墨及制得的改性负极材料进行红外测试，对比发现：改性后的负极材料在1100～1000 -1或800cm -1处出现Si-O键的信号，在1290～1270cm -1、1280～1210cm -1、或1265cm -1、或829cm -1、或1250～1110cm -1、或1240cm -1～1160cm -1、或1130～1000cm -1、或1125～1110cm -1、或1050～1000cm -1出现C-O的信号、在2890cm -1或1340cm -1出现C-H的信号。
改性负极材料C2：取10g的人造石墨分散在50g的乙二醇二甲醚中，搅拌1小时，加入0.05g的二甲基二氯硅烷搅拌0.5小时，加入0.2g的硅酸四乙酯，搅拌16小时用乙二醇二甲醚洗涤过滤后，在60℃的真空干燥12小时。
改性负极材料C3：取10g的人造石墨分散在50g的乙酸乙酯中，搅拌1小时，加入0.05g的二甲基二氯硅烷搅拌0.5小时，加入0.2g的硅酸四乙酯，搅拌16小时用乙酸乙酯洗涤过滤后，在60℃的真空干燥12小时。
改性负极材料C4：取10g的人造石墨分散在50g的乙醇中，搅拌1小时，加入0.05g的氨水搅拌0.5小时，加入0.2g的硅酸四乙酯，搅拌16小时用乙醇洗涤过滤后，在60℃的真空干燥12小时。
改性负极材料C5：取10g的人造石墨分散在50g的乙醇中，搅拌1小时，加入0.05g的盐酸搅拌0.5小时，加入0.2g的硅酸四乙酯，搅拌16小时用乙醇洗涤过滤后，在60℃的真空干燥12小时。
改性负极材料C6：取10g的人造石墨分散在50g的碳酸甲乙酯中，搅拌1小时，加入0.05g的二甲基二氯硅烷搅拌0.5小时，加入0.2g的硅酸四丙酯，搅拌16小时用碳酸甲乙酯洗涤过滤后，在60℃的真空干燥12小时。
改性负极材料C7：取10g的人造石墨(C0)分散在50g的碳酸甲乙酯中， 搅拌1小时，加入0.05g的二甲基二氯硅烷搅拌0.5小时，加入0.2g的硅酸四己烷，搅拌16小时用碳酸甲乙酯洗涤过滤后，在60℃的真空干燥12小时。
改性负极材料C8：取10g的人造石墨分散在50g的碳酸甲乙酯中，搅拌1小时，加入0.05g的二甲基二氯硅烷搅拌0.5小时，加入0.2g的碳酸四乙酯，搅拌16小时用碳酸甲乙酯洗涤过滤后，在60℃的真空干燥12小时。
改性负极材料C9：取10g的人造石墨分散在50g的碳酸甲乙酯中，搅拌1小时，加入0.05g的二甲基二氯硅烷搅拌0.5小时，加入0.2g的焦磷酸四乙酯，搅拌16小时用碳酸甲乙酯洗涤过滤后，在60℃的真空干燥12小时。
改性负极材料Si/C1：取10g的硅碳复合材料(贝特瑞新材料集团股份有限公司S500Si0)分散在50g的碳酸甲乙酯中，搅拌1小时，加入0.01g的二甲基二氯硅烷搅拌0.5小时，加入0.2g的硅酸四乙酯，搅拌16小时用碳酸甲乙酯洗涤过滤后，在60℃的真空干燥12小时。
改性负极材料Si/C2：取10g的硅碳复合材料(贝特瑞新材料集团股份有限公司S500)分散在50g的碳酸甲乙酯中，搅拌1小时，加入0.05g的二甲基二氯硅烷搅拌0.5小时，加入0.2g的硅酸四乙酯，搅拌16小时用碳酸甲乙酯洗涤过滤后，在60℃的真空干燥12小时。
改性负极材料Si/C3：取10g的硅碳复合材料(贝特瑞新材料集团股份有限公司S500)分散在50g的碳酸甲乙酯中，搅拌1小时，加入0.1g的二甲基二氯硅烷搅拌0.5小时，加入0.2g的硅酸四乙酯，搅拌16小时用碳酸甲乙酯洗涤过滤后，在60℃的真空干燥12小时。
改性负极材料Si/C4：取10g的硅碳复合材料(贝特瑞新材料集团股份有限公司S500)分散在50g的碳酸甲乙酯中，搅拌1小时，加入0.5g的二甲基二氯硅烷搅拌0.5小时，加入0.2g的硅酸四乙酯，搅拌16小时用碳酸甲乙酯洗涤过滤后，在60℃的真空干燥12小时。
改性负极材料Si/C5：取10g的硅碳复合材料(贝特瑞新材料集团股份有限公司S500)分散在50g的碳酸甲乙酯中，搅拌1小时，加入0.1g的二甲基二氯硅烷搅拌0.5小时，加入0.05g的硅酸四乙酯，搅拌16小时用碳酸甲乙酯洗涤过滤后，在60℃的真空干燥12小时。
改性负极材料Si6/C6：取10g的硅碳复合材料(贝特瑞新材料集团股份有限公司S500)分散在50g的碳酸甲乙酯中，搅拌1小时，加入0.1g的二甲 基二氯硅烷搅拌0.5小时，加入0.1g的硅酸四乙酯，搅拌16小时用碳酸甲乙酯洗涤过滤后，在60℃的真空干燥12小时。
改性负极材料Si/C7：取10g的硅碳复合材料(贝特瑞新材料集团股份有限公司S500)分散在50g的碳酸甲乙酯中，搅拌1小时，加入0.1g的二甲基二氯硅烷搅拌0.5小时，加入0.5g的硅酸四乙酯，搅拌16小时用碳酸甲乙酯洗涤过滤后，在60℃的真空干燥12小时。
改性负极材料Si/C8：取10g的硅碳复合材料(贝特瑞新材料集团股份有限公司S500)分散在50g的碳酸甲乙酯中，搅拌1小时，加入0.1g的二甲基二氯硅烷搅拌0.5小时，加入1g的硅酸四乙酯，搅拌16小时用碳酸甲乙酯洗涤过滤后，在60℃的真空干燥12小时。
上述各类改性负极材料的制备条件如表1所示。
表1
Figure PCTCN2022112711-appb-000005
Figure PCTCN2022112711-appb-000006
其中，“/”代表不进行改性处理。
实施例2
(1)负极片的制备：
C1-C7负极片：将改性负极材料、导电剂乙炔黑、粘结剂丁苯橡胶(SBR)、增稠剂羧甲基纤维素钠(CMC)按照重量比为90:4:4:2溶于溶剂去离子水中，均匀混合后制备成负极浆料；然后将负极浆料均匀涂覆在负极集流体铜箔上，烘干后得到负极膜片，再经过冷压、分切得到负极极片。
其中，改性负极材料分别采用上述改性负极材料C1～C7，制得的负极片相应地记为C1～C7。
(2)正极片的制备
LFP正极：将正极活性材料磷酸铁锂，导电剂乙炔黑、粘结剂聚偏二氟乙烯(PVDF)按重量比为90:5:5溶于溶剂N-甲基吡咯烷酮(NMP)中，充分搅拌混合均匀后得到正极浆料；之后将正极浆料均匀涂覆于正极集流体上，再经过烘干、冷压、分切，得到正极片。
(3)隔离膜的制备：以聚丙烯膜作为隔离膜。
(4)电解液的制备：
EL0电解液：在氩气气氛手套箱中(H 2O<0.1ppm，O 2<0.1ppm)，将有机溶剂EC/EMC按照体积比3/7混合均匀，加入12.5wt％LiPF 6锂盐溶解于有机溶剂中，加入1wt％PS，0.5wt％DTD，0.5wt％VC，2wt％FEC作为添加剂，搅拌均匀，得到相应的电解液。
(5)锂离子电池的制备
将正极片、隔离膜、负极片按顺序叠好，使隔离膜处于正、负极片之间起到隔离的作用，然后卷绕得到电极组件；将电极组件置于电池壳体中，干燥后注入电解液，再经过化成、静置等工艺制得锂离子电池。
其中，负极片分别采用上述负极片C1～C7，制得的锂离子电池分别记 为C1～C7。
(6)锂离子电池的性能测试：
1、电芯内阻(mΩ)
在25℃下，将出货的锂离子电池和45℃循环1000圈的锂离子电池以1C恒流充电至4.3V，然后以4.3V恒压充电至电流小于0.05C，然后再以1C放电30min，即将电芯的电量调整到50％SOC。然后将TH2523A交流内阻测试仪的正负表笔分别接触电池的正负极，通过内阻测试仪读取电池的内阻值，分别记录初始电芯内阻和循环1000圈后电芯内阻，分别记为RO和R1000。
2、45℃循环1000次容量保持率
在45℃下，将锂离子电池以1C恒流充电至4.3V，然后以4.3V恒压充电至电流小于0.05C，然后将锂离子电池以1C恒流放电至3.0V，此为一个充放电过程。如此反复进行充电和放电，计算锂离子电池循环1000次后的容量保持率。
锂离子电池45℃循环1000次后的容量保持率(％)C1000＝(第1000次循环的放电容量/首次循环的放电容量)×100％。
3、60℃存储300天容量保持率
在25℃下，以1C恒流充电至电压为4.3V，然后以4.3V恒压充电至电流为0.05C，然后将锂离子电池以1C恒流放电至3.0V，此为一个充放电过程此时测试锂。然后将满充的锂离子电池放入60℃恒温箱中，测试存储300天后的容量。
锂离子电池60℃存储300天后的容量保持率(％)T300＝(存储300天后的放电容量/首次循环的放电容量)×100％。
具体测试结果请见表2。
实施例3
实施例3与实施例2基本相同，不同之处在于：步骤(1)负极片的制备中将改性负极材料C1～C7分别替换成Si/C1～Si/C8，制得的负极片分别对应地记为Si/C1～Si/C8。
正极片的制备如下：将正极活性材料LiNi 0.8Co 0.1Mn 0.1O 2(NCM811)， 导电剂乙炔黑、粘结剂聚偏二氟乙烯(PVDF)按重量比为90:5:5溶于溶剂N-甲基吡咯烷酮(NMP)中，充分搅拌混合均匀后得到正极浆料；之后将正极浆料均匀涂覆于正极集流体上，再经过烘干、冷压、分切，得到正极片。
其余步骤与实施例2相同，制得的锂离子电池对应地记为Si/C1～Si/C8。具体参数及测试结果请见表2。
实施例4～7
实施例4～7与实施例3基本相同，实施例4～7中负极活性材料分别采用Si/C1、Si/C2、Si/C3、Si/C4；电解液分别采用EL1电解液、EL2电解液、EL3电解液、EL4电解液，电解液的具体制备过程如下：
EL1电解液：在氩气气氛手套箱中(H2O<0.1ppm，O2<0.1ppm)，将有机溶剂EC/EMC按照体积比3/7混合均匀，加入12.5wt％LiPF6锂盐溶解于有机溶剂中，加入1wt％PS，0.5wt％DTD，0.5wt％VC，2wt％FEC，1％硅酸四乙酯作为添加剂，搅拌均匀，得到相应的电解液。
EL2电解液：在氩气气氛手套箱中(H 2O<0.1ppm，O 2<0.1ppm)，将有机溶剂EC/EMC按照体积比3/7混合均匀，加入12.5wt％LiPF6锂盐溶解于有机溶剂中，加入1wt％PS，0.5wt％DTD，0.5wt％VC，2wt％FEC，1％硅酸四丙酯作为添加剂，搅拌均匀，得到相应的电解液。
EL3电解液：在氩气气氛手套箱中(H 2O<0.1ppm，O 2<0.1ppm)，将有机溶剂EC/EMC按照体积比3/7混合均匀，加入12.5wt％LiPF6锂盐溶解于有机溶剂中，加入1wt％PS，0.5wt％DTD，0.5wt％VC，2wt％FEC，1％碳酸四乙酯作为添加剂，搅拌均匀，得到相应的电解液。
EL4电解液：在氩气气氛手套箱中(H 2O<0.1ppm，O 2<0.1ppm)，将有机溶剂EC/EMC按照体积比3/7混合均匀，加入12.5wt％LiPF6锂盐溶解于有机溶剂中，加入1wt％PS(丙磺酸内脂)，0.5wt％DTD(硫酸亚乙酯)，0.5wt％VC(碳酸亚乙烯酯)，2wt％FEC(氯代碳酸乙烯酯)，1％焦磷酸四乙酯作为添加剂，搅拌均匀，得到相应的电解液。
其余步骤与实施例3相同，具体参数及测试结果请见表2。
对比例1
对比例1与实施例2基本相同，不同之处仅在于：对比例1中负极片中的负极活性材料直接采用C0(石墨)。
其余步骤与实施例2相同，具体参数及测试结果请见表2。
对比例2
对比例2与实施例2基本相同，不同之处在于：对比例2中负极片的制备中，改性负极材料采用改性负极材料C8。
其余步骤与实施例2相同，具体参数及测试结果请见表2。
对比例3
对比例3与实施例2基本相同，不同之处在于：对比例2中负极片的制备中，改性负极材料采用改性负极材料C9。
其余步骤与实施例2相同，具体参数及测试结果请见表2。
对比例4～7
对比例4～7分别与对比例1基本相同，不同之处在于：电解液分别采用EL1电解液、EL2电解液、EL3电解液、EL4电解液，电解液EL1～EL4的具体制备过程同实施例4～7。
其余步骤与对比例1相同，具体参数及测试结果请见表2。
对比例8
对比例8与实施例3基本相同，不同之处仅在于：对比例8中负极片中的负极活性材料直接采用硅碳复合材料Si0(即S500)。
其余步骤与实施例2相同，具体参数及测试结果请见表2。
表3中，RO(mΩ)、R1000(mΩ)、C1000(％)、T300％分别代表电芯初始内阻、电芯循环1000圈后的内阻、电芯在45℃循环1000次的容量保持率、电芯在60℃存储300天的容量保持率。
表2
Figure PCTCN2022112711-appb-000007
由表2数据可知：采用本申请的改性负极材料，可以降低电池的内阻、提高电池的循环性能。例如，与对比例1中没有经过改性的石墨负极相比，实施例2中石墨负极经过了硅酸酯的改性处理，有利于降低循环过程中的阻抗恶化，提高界面稳定性，进而提高循环容量保持率，说明经过硅酸酯处理的负极材料能改善电芯的循环稳定性。进一步地，对比例2和对比例3中的石墨负极使用非硅酸酯处理，从电芯性能反馈可以看出，电芯性能几乎没有任何改善，而对比例4～7的实验证明，直接在电解液中引入硅酸酯或类硅酸酯添加剂，对电池的循环性能也几乎没有改善作用。
同时，与对比例2中没有经过改性的碳硅复合负极S500相比，实施例3中经过硅酸酯改性处理的碳硅负极材料，对于电芯的循环稳定性和容量发挥具有改善作用。
最后应说明的是：以上各实施例仅用以说明本申请的技术方案，而非对其限制；尽管参照前述各实施例对本申请进行了详细的说明，本领域的普通技术人员应当理解：其依然可以对前述各实施例所记载的技术方案进行修改，或者对其中部分或者全部技术特征进行等同替换；而这些修改或者替换，并不使相应技术方案的本质脱离本申请各实施例技术方案的范围，其均应涵盖在本申请的权利要求和说明书的范围当中。尤其是，只要不存在结构冲突，各个实施例中所提到的各项技术特征均可以任意方式组合起来。本申请并不局限于文中公开的特定实施例，而是包括落入权利要求的范围内的所有技术方案。

Claims (17)

  1. 一种改性负极材料，其特征在于，所述改性负极材料包括负极活性基材及与所述负极活性基材通过氧原子连接的硅酸酯基，所述硅酸酯基的结构如式(1)所示：
    Figure PCTCN2022112711-appb-100001
    其中，各R 1分别独立地选自取代或未取代的碳原子数为1～10的烷基、或取代或未取代的碳原子数为1～10的烯基；
    *代表连接位点。
  2. 如权利要求1所述的改性负极材料，其特征在于，各R 1分别独立地选自取代或未取代的碳原子数为1～6的烷基；
    可选地，各R 1分别独立地选自取代或未取代的碳原子数为1～4的烷基。
  3. 如权利要求1～2任一项所述的改性负极材料，其特征在于，各R 1分别独立地选自未取代的碳原子数为1～4的链烷基或被卤素取代的碳原子数为1～4的链烷基。
  4. 如权利要求1～3任一项所述的改性负极材料，其特征在于，各R 1分别独立地选自甲基、乙基、正丙基、异丙基、正丁基、异丁基及其卤代物中的任意一种。
  5. 如权利要求1～4任一项所述改性负极材料，其特征在于，所述硅酸酯基满足如下(a)～(b)中至少一个条件：
    (a)所述硅酸酯基在所述改性负极材料中的占比为0.005wt％～5％；
    (b)所述硅酸酯基负载在所述负极活性基材表面形成包覆层。
  6. 如权利要求5所述的改性负极材料，其特征在于，所述包覆层的厚度为1nm～20nm。
  7. 如权利要求1～6任一项所述的改性负极材料，其特征在于，所述负极活性基材包括碳基材和硅基材中的至少一种。
  8. 一种改性负极材料的制备方法，其特征在于，包括如下步骤：
    将负极活性基材与式(2)化合物进行酯交换反应，制备改性负极材料；
    Figure PCTCN2022112711-appb-100002
    其中，所述负极活性基材的表面含有羟基；式(2)中R 1与权利要求1中R 1相同。
  9. 如权利要求8所述的改性负极材料的制备方法，其特征在于，所述酯交换反应的温度为50℃～80℃，时间为6h～24h。
  10. 如权利要求8～9任一项所述的改性负极材料的制备方法，其特征在于，所述式(2)化合物与所述负极活性基材的质量比为(0.05～1)：10。
  11. 如权利要求8～10任一项所述的改性负极材料的制备方法，其特征在于，所述酯交换反应在酯交换催化剂的作用下进行，所述酯交换催化剂满足如下(c)～(d)中至少一个条件：
    (c)所述酯交换催化剂包括碱性催化剂、酸性催化剂及有机硅烷中的至少一种；
    可选地，所述酯交换催化剂包括无机碱、有机碱、无机酸、有机酸及有机氯硅烷中的至少一种；
    可选地，所述酯交换催化剂包括氢氧化钠、氢氧化钾、盐酸、硫酸、氨水及二甲基二氯硅烷中的至少一种；
    (d)所述酯交换催化剂与所述负极活性基材的质量比为(0.01～0.5)：10。
  12. 如权利要求8～11任一项所述的改性负极材料的制备方法，其特征在于，所述酯交换反应在有机溶剂中进行，所述有机溶剂满足如下(e)～(f)中至少一个条件：
    (e)所述有机溶剂包括碳酸酯类溶剂、羧酸酯类溶剂、醇类溶剂和醚类溶剂中的至少一种；
    可选地，所述有机溶剂包括碳酸二甲酯、碳酸甲乙酯、乙醇和乙二醇二甲醚中的至少一种；
    (f)所述有机溶剂与所述负极活性基材的质量比为(10～300)：10。
  13. 一种负极片，其特征在于，所述负极片包括集流体及设于所述集流体表面的负极活性层，所述负极活性层的组分包括如权利要求1～7任一项 所述的改性负极材料或如权利要求8～12任一项改性负极材料的制备方法制备得到的改性负极材料。
  14. 如权利要求13所述的负极片，其特征在于，所述改性负极材料在所述负极活性层中的质量占比为70％～99.5％。
  15. 一种二次电池，其特征在于，所述二次电池包含如权利要求13～14任一项所述的负极片。
  16. 如权利要求15所述的二次电池，其特征在于，所述负极片中的所述负极活性层表面负载有硅酸盐，所述硅酸盐中的硅酸基团源自于所述硅酸酯基的分解。
  17. 一种用电装置，其特征在于，所述用电装置包括如权利要求15～16任一项所述的二次电池。
PCT/CN2022/112711 2022-08-16 2022-08-16 改性负极材料及其制备方法、负极片、二次电池及用电装置 WO2024036469A1 (zh)

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6723432B2 (en) * 2001-03-27 2004-04-20 Shin-Etsu Chemical Co., Ltd. Electrode-forming compositions and electrode members
CN102007627A (zh) * 2008-04-18 2011-04-06 株式会社丰田自动织机 锂离子二次电池用负极及其制造方法
CN105390678A (zh) * 2015-11-03 2016-03-09 宁德新能源科技有限公司 负极材料以及包括该负极材料的锂离子电池
CN106169558A (zh) * 2016-07-28 2016-11-30 惠州市豪鹏科技有限公司 一种电池负极片及其制备方法和应用
CN108232129A (zh) * 2016-12-21 2018-06-29 深圳市比克动力电池有限公司 锂离子电池负极材料、负极片和锂离子电池

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6723432B2 (en) * 2001-03-27 2004-04-20 Shin-Etsu Chemical Co., Ltd. Electrode-forming compositions and electrode members
CN102007627A (zh) * 2008-04-18 2011-04-06 株式会社丰田自动织机 锂离子二次电池用负极及其制造方法
CN105390678A (zh) * 2015-11-03 2016-03-09 宁德新能源科技有限公司 负极材料以及包括该负极材料的锂离子电池
CN106169558A (zh) * 2016-07-28 2016-11-30 惠州市豪鹏科技有限公司 一种电池负极片及其制备方法和应用
CN108232129A (zh) * 2016-12-21 2018-06-29 深圳市比克动力电池有限公司 锂离子电池负极材料、负极片和锂离子电池

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