CN114743803B - High-voltage hybrid lithium ion supercapacitor and preparation method thereof - Google Patents

High-voltage hybrid lithium ion supercapacitor and preparation method thereof Download PDF

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CN114743803B
CN114743803B CN202210344177.8A CN202210344177A CN114743803B CN 114743803 B CN114743803 B CN 114743803B CN 202210344177 A CN202210344177 A CN 202210344177A CN 114743803 B CN114743803 B CN 114743803B
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CN114743803A (en
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卢文
杨晓萍
成方
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Kunming Yunda New Energy Co ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
    • H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
    • H01G11/22—Electrodes
    • H01G11/24—Electrodes characterised by structural features of the materials making up or comprised in the electrodes, e.g. form, surface area or porosity; characterised by the structural features of powders or particles used therefor
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
    • H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
    • H01G11/22—Electrodes
    • H01G11/30—Electrodes characterised by their material
    • H01G11/32—Carbon-based
    • H01G11/36—Nanostructures, e.g. nanofibres, nanotubes or fullerenes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
    • H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
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    • H01G11/58—Liquid electrolytes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
    • H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
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    • H01G11/58—Liquid electrolytes
    • H01G11/62—Liquid electrolytes characterised by the solute, e.g. salts, anions or cations therein
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
    • H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
    • H01G11/54—Electrolytes
    • H01G11/58—Liquid electrolytes
    • H01G11/64—Liquid electrolytes characterised by additives
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
    • H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
    • H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
    • H01G11/84—Processes for the manufacture of hybrid or EDL capacitors, or components thereof
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
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    • Y02E60/13—Energy storage using capacitors

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Abstract

The invention discloses a high-voltage hybrid lithium ion supercapacitor and a preparation method thereof. The high-voltage hybrid lithium ion supercapacitor comprises a positive plate, a negative plate, a diaphragm between the positive plate and the negative plate, electrolyte filled in gaps between the positive plate and the negative plate and a diaphragm, and a shell, wherein the positive plate and/or the negative plate consists of a current collector and electrode materials coated on the surface of the current collector and comprising nano carbon materials, and the electrolyte is a high-voltage electrolyte formed by mixing an organic solvent, lithium salt and an additive. The preparation method of the high-voltage hybrid lithium ion supercapacitor comprises the steps of high-voltage electrolyte preparation, positive plate preparation, negative plate preparation and packaging. According to the invention, the nano carbon material is introduced to carry out composite modification on the 5V positive electrode material and the porous carbon material, and the capacitor has higher working voltage, energy density, power density, safety and cycle service life by optimizing electrolyte and optimizing the capacity ratio of the positive electrode to the negative electrode of the capacitor.

Description

High-voltage hybrid lithium ion supercapacitor and preparation method thereof
Technical Field
The invention belongs to the technical field of electrochemical energy storage, and particularly relates to a high-voltage hybrid lithium ion supercapacitor with higher working voltage, energy density, power density, safety and cycle service life and a preparation method thereof.
Background
Since the 20 th century, economy has rapidly developed, resources are exhausted, pollution is becoming serious, and it is urgent to find new renewable energy sources capable of replacing fossil fuels such as petroleum, coal, natural gas and the like. Meanwhile, the rapid development of new energy technologies brings about urgent demands for new energy storage technologies.
Super-capacitors (also called electrochemical capacitors) are new energy storage elements between conventional capacitors and chemical batteries, which have been developed recently in recent decades at home and abroad. Due to its higher power density (10 3 ~10 4 Wkg -1 ) Super capacitors have been widely used in the fields of transportation, renewable energy sources, industry, consumer electronics, etc., with unique properties such as ultra-long cycle life (up to hundreds of thousands times) and a wide operating temperature range (-40-70 ℃).
Currently, commercial supercapacitors are mainly organic electric double layer capacitors composed of two symmetrical Activated Carbon (AC) electrodes and an organic electrolyte, which store electric energy by using an electric double layer at the interface between the AC electrodes and the electrolyte, as in patent Z199208460.1 and CN1229517a. The working voltage of the super capacitor is only 2.7V, and the energy density is relatively low <10Whkg -1 ) Limiting its further application and development.
According to the energy formula e=0.5 CV of the supercapacitor 2 And power formula p=v 2 It is clear that the energy density and the power density can be improved in terms of both the specific capacity C and the operating voltage V. Wherein, the capacitor specific capacity C can be improved by improving the performance (such as specific surface area, aperture and aperture distribution, granularity and granularity distribution, etc.) of the electrode material or adopting an asymmetric mixed structure to package the capacitor; further, the asymmetric hybrid structure results in a higher operating voltage for the capacitor, thereby increasing the energy density and power density of the resulting capacitor.
Lithium ion batteries have higher operating voltages and energy densities than electric double layer capacitors. Positive electrode material of lithium ion batteryThe material is combined with an active carbon electrode of an electric double layer capacitor to form a hybrid lithium ion supercapacitor, and is an important direction for researching and developing the supercapacitor with high energy density in recent years. The device generally adopts the positive electrode of a lithium ion battery to replace the active carbon positive electrode of the double-layer capacitor, and forms a hybrid lithium ion supercapacitor with the active carbon negative electrode. The charge and discharge of the lithium ion battery material mainly relates to reversible intercalation/deintercalation of lithium ions, and the charge and discharge of the activated carbon material still belongs to an electric double layer mechanism of ion adsorption/desorption, so that the constructed hybrid lithium ion supercapacitor has the characteristics of a lithium ion battery and an electric double layer capacitor, and has higher power density and higher working voltage and energy density than the lithium ion battery. Common lithium ion battery cathode materials, such as lithium cobalt oxide (LiCoO) 2 ) Lithium manganate (LiMn) 2 O 4 ) Lithium iron phosphate (LiFePO) 4 ) Ternary materials (NCM) have been used for research and development of hybrid lithium ion supercapacitors. However, this type of positive electrode material is limited by its limited lithium intercalation potential (about 4Vvs.Li/Li + ) The working voltage (2.0-3.0V), energy density and power density of the obtained hybrid lithium ion super capacitor are required to be further improved.
In the research of novel positive electrode materials of lithium ion batteries, a charging and discharging platform is generally set at 4.5V #vs.Li/Li + ) The above materials are referred to as high potential positive electrode materials, or 5V positive electrode materials. According to the current research results, the high-potential positive electrode material mainly comprises spinel material LiM x Mn 2-x O 4 (x is more than 0 and less than 1, M is transition metal elements such as iron, copper, cobalt, nickel, chromium and the like), olivine material LiMPO 4 (M is transition metal element such as Mn, co, ni, cr, etc.), and lithium-rich Mn-based material xLi having layered structure 2 MnO 3 •（1-x）LiMO 2 (x is more than 0 and less than 1, M is transition metal elements such as manganese, cobalt, nickel and the like). Along with the development and utilization of the 5V novel high-potential lithium ion battery anode materials, the application research of the 5V novel high-potential lithium ion battery anode materials in the aspect of the hybrid lithium ion super capacitor is also greatly concerned. Because the material has higher potential The working voltage, energy density and power density of the super capacitor can be greatly improved. Wherein, spinel LiNi 0.5 Mn 1.5 O 4 The (LNMO) positive electrode material is prepared by the method of preparing a lithium ion battery by the method of preparing a 2 O 4 On the basis of the development of (a) it has a relatively high potential (4.7Vvs.Li/Li + ) Higher theoretical capacity (147 mAhg) -1 ) The lithium ion battery positive electrode material has the characteristics of good safety, low cost, abundant resources, no toxicity and the like, is considered as one of the lithium ion battery positive electrode materials with the highest potential of the next generation, and has been used for application research of the hybrid lithium ion super capacitor. For example, in 2005, li et al combined LNMO positive electrode with activated carbon negative electrode and conventional carbonate electrolyte to prepare a hybrid lithium ion capacitor with an operating voltage of 2.8V (H.Li, L.Cheng, andY.Xia, A Hybrid Electrochemical Supercapacitor Basedona V Li-Ion Battery Cathodeand ActiveCarbon,Electrochem.Solid-StateLett.8, a433 (2005)); in 2014, adrian brandt et al packaged hybrid capacitors with the same electrode materials and electrolyte and increased their operating voltage to 3.3V (A.Brandt, A.Balducci, U.Rodehorst, S.Menne, M.Winter, andA.Bhaskar, investigations aboutthe Useandthe Degradation Mechanism of LiNi 0.5 Mn 1.5 O 4 ina HighPower LIC，J.Electrochem.Soc.161, a1139 (2014)). However, the power performance of the resulting capacitor is poor due to the poor rate capability of the conventional LNMO and activated carbon materials used in these studies. On the other hand, the conventional carbonate electrolyte is easy to be decomposed electrochemically when the voltage is higher than 4.4V, and the electrolyte lacks a proper protective agent for protecting LNMO to work normally under high voltage, so that the working voltage, energy density and power density of the obtained capacitor are still lower, the cycle life is short, and the practical application of the LNMO-based hybrid lithium ion supercapacitor is limited.
Disclosure of Invention
Aiming at the problems and the defects existing in the prior art, the invention provides a high-voltage hybrid lithium ion supercapacitor with higher working voltage, energy density, power density, safety and cycle service life, and also provides a preparation method of the high-voltage hybrid lithium ion supercapacitor, which has the advantages of simple preparation process, environmental protection and low cost.
The high-voltage hybrid lithium ion supercapacitor is realized by the following steps: the lithium ion battery comprises a positive plate, a negative plate, a diaphragm between the positive plate and the negative plate, electrolyte filled in gaps between the positive plate and the negative plate and a diaphragm, and a shell, wherein the positive plate and/or the negative plate consists of a current collector and electrode materials coated on the surface of the current collector and comprising nano carbon materials, and the electrolyte is a high-voltage electrolyte formed by mixing an organic solvent, lithium salt and an additive.
The preparation method of the high-voltage hybrid lithium ion supercapacitor is realized by the following steps: the method comprises the steps of high-voltage electrolyte preparation, positive electrode plate preparation, negative electrode plate preparation and packaging, and specifically comprises the following steps:
A. preparing a high-voltage electrolyte: under the condition of controlling inert gas atmosphere with oxygen of less than 1ppm and water of less than 1ppm, uniformly mixing the selected organic solvent, lithium salt and additive according to a certain mass ratio to prepare high-voltage electrolyte;
B. Preparing a positive plate: adding a 5V positive electrode material, a nano carbon material, a conductive agent and a binder into N-methyl pyrrolidone according to a certain mass ratio, stirring at a high speed in vacuum to form positive electrode slurry, uniformly coating the positive electrode slurry on the surface of a current collector, and drying, rolling and cutting to obtain a positive electrode plate;
C. preparing a negative electrode sheet: adding a porous carbon material, a nano carbon material, a conductive agent and a binder into deionized water according to a certain mass ratio, stirring at a high speed in vacuum to form negative electrode slurry, uniformly coating the negative electrode slurry on the surface of a current collector, and drying, rolling and cutting to obtain a negative electrode plate;
D. and (3) packaging: and under the condition of controlling the inert gas atmosphere of oxygen less than 1ppm and moisture less than 1ppm, packaging the high-voltage electrolyte, the positive plate, the negative plate and the diaphragm to obtain the high-voltage hybrid lithium ion supercapacitor.
Compared with the prior art, the invention has the following beneficial effects:
1. according to the invention, the nano carbon material is introduced to respectively carry out composite modification on the 5V positive electrode material and the porous carbon material to prepare the nano composite positive electrode material and the nano composite negative electrode material, so that the conductivity and the multiplying power performance of the 5V positive electrode material and the porous carbon material are improved, and the power characteristic, the safety and the cycle service life of the capacitor are improved.
2. According to the invention, the prepared high-voltage electrolyte is suitable for the high-voltage mixed lithium ion super capacitor by selecting the organic solvent suitable for the high-voltage electrolyte, the lithium salt electrolyte suitable for the high-voltage electrolyte and the electrolyte additive capable of stabilizing the high-voltage positive electrode material.
3. According to the invention, the nano carbon material composite modified 5V positive electrode, the porous carbon material negative electrode and the high-voltage electrolyte are packaged into the capacitor, and the capacity ratio of the positive electrode to the negative electrode is optimized, so that the charge and discharge processes of the positive electrode and the negative electrode can be better matched, the working voltage of the capacitor is improved and stabilized (reaching more than 3.4V), and the requirement of the high-energy density/high-power density supercapacitor is further met.
Therefore, the high-voltage hybrid lithium ion supercapacitor disclosed by the invention has higher working voltage, energy density, power density, safety and cycle service life, and the preparation method of the high-voltage hybrid lithium ion supercapacitor disclosed by the invention is simple in process, short in flow, environment-friendly, low in cost and suitable for industrial production.
Drawings
FIG. 1 is a cyclic voltammogram of the high voltage electrolyte prepared from example 1;
FIG. 2 is a high power scanning electron microscope image of the LNMO/SP/KS/PVDF (80/5/5/10) positive plate of the high voltage hybrid lithium ion supercapacitor prepared by example 2;
FIG. 3 is a high power scanning electron microscope image of the LNMO/CNT/SP/KS/PVDF (80/0.3/4.85/4.85/10) positive plate of the high voltage hybrid lithium ion supercapacitor prepared by example 2;
FIG. 4 is a high power scanning electron microscope image of the LNMO/CNT/SP/KS/PVDF (80/5/2.5/2.5/10) positive plate of the high voltage hybrid lithium ion supercapacitor prepared by example 2;
FIG. 5 is a cyclic voltammogram of a positive half cell of LNMO/CNT/SP/KS/PVDF (80/0.3/4.85/4.85/10) prepared in example 2;
fig. 6 is a magnification test curve of the positive half cell prepared from example 2;
FIG. 7 is a high power scanning electron microscope image of an AC/SP/SBR/CMC (90/5/3/2) negative plate of the high voltage hybrid lithium ion supercapacitor prepared by example 3;
FIG. 8 is a high power scanning electron microscope image of the AC/CNT/SP/SBR/CMC (90/0.625/4.375/3/2) negative plate of the high voltage hybrid lithium ion supercapacitor prepared by example 3;
FIG. 9 is a high power scanning electron microscope image of an AC/CNT/CMC (90/5/3/2) negative plate of the high voltage hybrid lithium ion supercapacitor prepared by example 3;
FIG. 10 is a cyclic voltammogram of an AC/CNT/SP/SBR/CMC (90/0.625/4.375/3/2) negative half cell prepared from example 3;
fig. 11 is a magnification test curve of the negative half cell prepared from example 3;
FIG. 12 is a cyclic voltammogram of the high voltage hybrid lithium ion supercapacitor packaged in example 4 over a voltage range of 0-3.5V;
FIG. 13 is a graph of the cycle life of the high voltage hybrid lithium ion supercapacitor packaged in example 4 over a voltage range of 0-3.45V;
FIG. 14 is a high power scanning electron microscope image of an electrode pad of a conventional symmetrical electric double layer supercapacitor prepared from comparative example 1;
FIG. 15 is a cyclic voltammogram of a conventional symmetric double layer supercapacitor encapsulated by comparative example 1 over a voltage range of 0-2.7V;
FIG. 16 is a graph showing a cycle life test of a conventional symmetrical double electric layer supercapacitor packaged in comparative example 1 in a voltage range of 0 to 2.7V;
fig. 17 is a graph showing energy density versus power density for the high voltage hybrid lithium ion supercapacitor packaged in example 4 and the conventional symmetric electric double layer supercapacitor packaged in comparative example 1.
Detailed Description
The invention is further illustrated in the following figures and examples, which are not intended to be limiting in any way, and any alterations or modifications based on the teachings of the invention are within the scope of the invention.
The invention relates to a high-voltage hybrid lithium ion supercapacitor, which comprises a positive plate, a negative plate, a diaphragm between the positive plate and the negative plate, electrolyte filled in gaps between the positive plate and the negative plate and the diaphragm, and a shell, wherein the positive plate and/or the negative plate consists of a current collector and electrode materials coated on the surface of the current collector and comprising nano carbon materials, and the electrolyte is a high-voltage electrolyte formed by mixing an organic solvent, lithium salt and an additive.
The electrode material of the positive plate consists of a 5V positive electrode material, a nano carbon material, a conductive agent and a binder, the electrode material of the negative plate consists of a porous carbon material, a nano carbon material, a conductive agent and a binder, and the nano carbon material is at least one of a carbon nano tube, a carbon nano fiber and graphene.
The kind of the carbon nanotube is not limited, and may be a single-walled carbon nanotube (SWCNT) and/or a multi-walled carbon nanotube (MWCNT); the kind of the carbon nanofibers is not limited; the type of the graphene is not limited, and may be single-layer graphene and/or multi-layer graphene.
The conductive agent is at least one of conductive graphite, conductive carbon black and conductive carbon fiber.
The binder is at least one of polytetrafluoroethylene, polyvinylidene fluoride, carboxymethyl cellulose, polyvinyl alcohol, styrene-butadiene rubber and acrylic resin.
The current collector is one or an alloy of at least any two of sheet, mesh or foam Cu, al, ni, ag.
The current collector is a corrosion aluminum foil, a porous aluminum foil, a carbon-coated aluminum foil or a polished aluminum foil.
The diaphragm is at least one of polypropylene porous film, polyethylene porous film, polypropylene/polyethylene composite porous film, cellulose acetate porous diaphragm, glass fiber porous film, nylon and asbestos paper.
The 5V positive electrode material is spinel material LiM x Mn 2-x O 4 Olivine-type material LiNPO 4 Layered lithium-rich manganese-based material xLi 2 MnO 3 •（1-x）Li Y O 2 At least one of (a) and (b), wherein: 0 < x < 1, m= Fe, cu, co, ni, cr, n= Mn, co, ni, cr, y=mn, co, ni.
The electrode material of the positive plate comprises the following substances in percentage by mass: 50-97.99% of 5V positive electrode material, 0.01-10% of nano carbon material, 1-50% of conductive agent and 1-50% of binder.
The porous carbon material is at least one of active carbon powder, active carbon cloth, active carbon fiber, nano carbon material, carbon aerogel, porous graphite and porous hard carbon, and the electrode material of the negative electrode plate comprises the following substances in percentage by mass: 50-97.99% of porous carbon material, 0.01-10% of nano carbon material, 1-50% of conductive agent and 1-50% of binder.
The capacity ratio of the positive electrode to the negative electrode of the high-voltage hybrid lithium ion supercapacitor is 1:1-10:1.
The concentration of lithium salt in the high-voltage electrolyte is 0.1-10 mol L -1 The lithium salt is lithium perchlorate (LiClO) 4 ) Lithium hexafluorophosphate (LiPF) 6 ) Lithium bisoxalato borate (LiBOB), liBF 4 Lithium tetrafluoroborate, lithium difluorooxalato borate (LiODFB), lithium bis (trifluoromethylsulfonyl) imide (LiTFSI), lithium bis (fluorosulfonyl) imide (LiFSI), lithium difluorophosphate (LiPO) 2 F 2 ) At least one of lithium difluorooxalate phosphate (LiODFP).
The high-voltage electrolyte comprises 0.01-10% of additive by mass percent, wherein the additive is triphenyl phosphite (TPPi), lithium oxalate borate (LiBOB), lithium difluoroborate (LiODFB), lithium fluoride bis (malonate) borate (LiBMB), lithium difluorosulfate borate (LiBSO) 4 F 2 ) At least one of trifluoromethyl phenyl sulfide (PTS) and trimethyl borate (TMB).
The organic solvent in the high-voltage electrolyte is at least one of Ethylene Carbonate (EC), dimethyl carbonate (DMC), diethyl carbonate (DEC), methyl ethyl carbonate (EMC), propylene Carbonate (PC), fluoroethylene carbonate (FEC), fluoropropylene carbonate (TFPC), gamma Butyrolactone (GBL), gamma Valerolactone (GVL), N-Dimethylformamide (DMF), acetonitrile (AN) and Fluoroacetonitrile (FAN).
The high-voltage hybrid lithium ion supercapacitor is any one of button-shaped, cylindrical, square and special-shaped packaging, and is any one of steel shell, plastic shell, aluminum shell and aluminum plastic film packaging.
The preparation method of the high-voltage hybrid lithium ion supercapacitor comprises the steps of preparing a high-voltage electrolyte, preparing a positive plate, preparing a negative plate and packaging, and specifically comprises the following steps of:
A. preparing a high-voltage electrolyte: under the condition of controlling inert gas atmosphere with oxygen of less than 1ppm and water of less than 1ppm, uniformly mixing the selected organic solvent, lithium salt and additive according to a certain mass ratio to prepare high-voltage electrolyte;
B. preparing a positive plate: adding a 5V positive electrode material, a nano carbon material, a conductive agent and a binder into N-methyl pyrrolidone according to a certain mass ratio, stirring at a high speed in vacuum to form positive electrode slurry, uniformly coating the positive electrode slurry on the surface of a current collector, and drying, rolling and cutting to obtain a positive electrode plate;
C. preparing a negative electrode sheet: adding a porous carbon material, a nano carbon material, a conductive agent and a binder into deionized water according to a certain mass ratio, stirring at a high speed in vacuum to form negative electrode slurry, uniformly coating the negative electrode slurry on the surface of a current collector, and drying, rolling and cutting to obtain a negative electrode plate;
D. And (3) packaging: and under the condition of controlling the inert gas atmosphere of oxygen less than 1ppm and moisture less than 1ppm, packaging the high-voltage electrolyte, the positive plate, the negative plate and the diaphragm to obtain the high-voltage hybrid lithium ion supercapacitor.
The step A is preparedThe concentration of lithium salt in the high-voltage electrolyte is 0.1-10 mol L -1 And/or the content of the additive is 0.01-10% by mass percent.
The organic solvent in the step A is at least one of Ethylene Carbonate (EC), dimethyl carbonate (DMC), diethyl carbonate (DEC), methyl ethyl carbonate (EMC), propylene Carbonate (PC), fluoroethylene carbonate (FEC), fluoropropylene carbonate (TFPC), gamma Butyrolactone (GBL), gamma Valerolactone (GVL), N-Dimethylformamide (DMF), acetonitrile (AN) and Fluoroacetonitrile (FAN).
The lithium salt in the step A is lithium perchlorate (LiClO) 4 ) Lithium hexafluorophosphate (LiPF) 6 ) Lithium bisoxalato borate (LiBOB), liBF 4 Lithium tetrafluoroborate, lithium difluorooxalato borate (LiODFB), lithium bis (trifluoromethylsulfonyl) imide (LiTFSI), lithium bis (fluorosulfonyl) imide (LiFSI), lithium difluorophosphate (LiPO) 2 F 2 ) At least one of lithium difluorooxalate phosphate (LiODFP).
The additive in the step A is triphenyl phosphite (TPPi), lithium oxalate borate (LiBOB), lithium difluoroborate (LiODFB), lithium bis (malonate) borate fluoride (LiBMB), lithium difluorosulfate borate (LiBSO) 4 F 2 ) At least one of trifluoromethyl phenyl sulfide (PTS) and trimethyl borate (TMB).
The 5V positive electrode material in the step B is spinel material LiM x Mn 2-x O 4 Olivine-type material LiNPO 4 Layered lithium-rich manganese-based material xLi 2 MnO 3 •（1-x）Li Y O 2 At least one of (a) and (b), wherein: 0 < x < 1, m= Fe, cu, co, ni, cr, n= Mn, co, ni, cr, y=mn, co, ni.
The content of each substance in the step B is as follows by mass percent: 50-97.99% of 5V positive electrode material, 0.01-10% of nano carbon material, 1-50% of conductive agent and 1-50% of binder.
The content of each substance in the step C is as follows in percentage by mass: 50-97.99% of porous carbon material, 0.01-10% of nano carbon material, 1-50% of conductive agent and 1-50% of binder.
The porous carbon material in the step C is at least one of activated carbon powder, activated carbon cloth, activated carbon fiber, nano carbon material, carbon aerogel, porous graphite and porous hard carbon.
And the conductive agent in the step B and/or the step C is at least one of conductive graphite, conductive carbon black and conductive carbon fiber.
And the adhesive in the step B and/or the step C is at least one of polytetrafluoroethylene, polyvinylidene fluoride, carboxymethyl cellulose, polyvinyl alcohol, styrene-butadiene rubber and acrylic resin.
And (3) the nano carbon material in the step B and/or the step C is at least one of carbon nano tubes, carbon nano fibers and graphene.
The current collector in the step B and/or the step C is one or an alloy of at least any two of sheet-shaped, net-shaped or foam-shaped Cu, al, ni, ag.
And D, the capacity ratio of the positive electrode to the negative electrode of the high-voltage hybrid lithium ion supercapacitor is 1:1-10:1.
Example 1
The invention relates to preparation and test of a high-voltage electrolyte of a high-voltage hybrid lithium ion supercapacitor.
(1) Containing 1mol L -1 LiPF 6 And preparation of 0.2% TPPi EC DMC EMC (1:1:1) high voltage electrolyte
In the control of oxygen<1 ppm) and moisture%<1 ppm), uniformly mixing and stirring selected organic solvents of Ethylene Carbonate (EC), dimethyl carbonate (DMC) and methyl ethyl carbonate (EMC) according to the volume ratio of 1:1:1 to obtain a required mixed solvent; accurately weighing a certain mass of lithium salt lithium hexafluorophosphate (LiPF) 6 ) Adding triphenyl phosphite (TPPi) as additive into the mixed solvent, dissolving, stirring, adding a certain amount of molecular sieve, standing for 24 hr to obtain a solution containing 1mol -1 LiPF 6 And 0.2% tppi of a high voltage electrolyte.
(2) Testing of electrolyte
The glassy carbon electrode is used as a working electrode, the lithium sheet is used as a reference electrode,platinum mesh is used as counter electrode, and 5mVs is used as counter electrode -1 Performing cyclic voltammetry (as shown in figure 1) on the high voltage electrolyte; the test results show that: oxidative decomposition of the solvent in the electrolyte occurs at a higher potential (6.6Vvs.Li/Li + ) That is, the electrolyte has a wide safety electrochemical window; the oxidation peak, which starts to appear at 4.2V, corresponds to the oxidation of additive TPPi, indicating that it is able to oxidize and form an effective protective film on the electrode surface before the solvolysis of the electrolyte.
Example 2
The invention relates to preparation and test of a positive plate of a high-voltage hybrid lithium ion supercapacitor.
1. Preparation of high-voltage hybrid lithium ion supercapacitor positive plate
(1) Preparation of LNMO/SP/KS/PVDF (80/5/5/10) pole piece
Step one: accurately weighing polyvinylidene fluoride (PVDF) powder with certain mass, adding the polyvinylidene fluoride (PVDF) powder into a vacuum stirring tank, then adding N-methylpyrrolidone (NMP) with certain mass (the mass ratio of PVDF to NMP is 1:20), setting the rotating speed of a vacuum stirrer to be 500r/min, and stirring for 60min at room temperature to prepare a mixed solution of PVDF and NMP; adding 5V positive electrode material LiNi with certain mass 0.5 Mn 1.5 O 4 (LNMO) and stirring for 90min to obtain LNMO, PVDF, NMP mixed slurry; respectively adding conductive carbon black (SP) and conductive graphite (KS) with certain mass, stirring for 60min, and preparing the anode material electrode slurry with the LNMO/SP/KS/PVDF mass ratio of 80:5:5:10, wherein the LNMO/SP/KS/PVDF mass ratio is uniformly dispersed.
Step two: vacuumizing the positive electrode material electrode slurry, standing for 10min, filtering by a 120-mesh filter screen, and coating the positive electrode material electrode slurry on an aluminum foil current collector according to a certain thickness to obtain a pole piece; vacuum drying the obtained pole piece for 3-6 hours at 80 ℃, and then rolling according to a rolling ratio of 36%; and then slicing the rolled pole piece by using a slicer to obtain a round pole piece with the diameter of 12mm, and then vacuum drying at 120 ℃ for 10-12 h to obtain the positive pole piece electrode of the high-voltage hybrid lithium ion supercapacitor.
(2) Preparation of LNMO/CNT/SP/KS/PVDF (80/0.3/4.85/4.85/10) pole piece
Step one: accurately weighing polyvinylidene fluoride (PVDF) powder with certain mass, adding the polyvinylidene fluoride (PVDF) powder into a vacuum stirring tank, then adding N-methylpyrrolidone (NMP) with certain mass (the mass ratio of PVDF to NMP is 1:20), setting the rotating speed of a vacuum stirrer to be 500r/min, and stirring for 60min at room temperature to prepare a mixed solution of PVDF and NMP; adding Carbon Nano Tube (CNT) with certain mass, stirring for 60min to obtain a CNT, PVDF, NMP mixed solution; adding 5V positive electrode material LiNi with certain mass 0.5 Mn 1.5 O 4 (LNMO) and stirring for 90min to obtain LNMO, CNT, PVDF, NMP mixed slurry; respectively adding conductive carbon black (SP) and conductive graphite (KS) with certain mass, stirring for 60min, and preparing the anode material electrode slurry with the mass part ratio of LNMO/CNT/SP/KS/PVDF of 80:0.3:4.85:4.85:10, wherein the LNMO/CNT/SP/KS/PVDF is uniformly dispersed.
Step two: and (3) preparing a pole piece by the electrode slurry of the positive electrode material according to the method of the step (1) in the embodiment 2, so as to prepare the positive electrode piece electrode of the high-voltage hybrid lithium ion supercapacitor.
(3) Preparation of LNMO/CNT/SP/KS/PVDF (80/5/2.5/2.5/10) pole piece
Step one: accurately weighing polyvinylidene fluoride (PVDF) powder with certain mass, adding the polyvinylidene fluoride (PVDF) powder into a vacuum stirring tank, then adding N-methylpyrrolidone (NMP) with certain mass (the mass ratio of PVDF to NMP is 1:20), setting the rotating speed of a vacuum stirrer to be 500r/min, and stirring for 60min at room temperature to prepare a mixed solution of PVDF and NMP; adding Carbon Nano Tube (CNT) with certain mass, stirring for 60min to obtain a CNT, PVDF, NMP mixed solution; adding 5V positive electrode material LiNi with certain mass 0.5 Mn 1.5 O 4 (LNMO) and stirring for 90min to obtain LNMO, CNT, PVDF, NMP mixed slurry; respectively adding conductive carbon black (SP) and conductive graphite (KS) with certain mass, stirring for 60min, and preparing the anode material electrode slurry with the mass part ratio of LNMO/CNT/SP/KS/PVDF of 80:5:2.5:2.5:10, wherein the LNMO/CNT/SP/KS/PVDF is uniformly dispersed.
Step two: and (3) preparing a pole piece by the electrode slurry of the positive electrode material according to the method of the step (1) in the embodiment 2, so as to prepare the positive electrode piece electrode of the high-voltage hybrid lithium ion supercapacitor.
2. Testing of positive plate of high-voltage hybrid lithium ion supercapacitor
(1) High power Scanning Electron Microscope (SEM) testing
Characterization tests of the morphology of the LNMO/SP/KS/PVDF (80/5/5/10), LNMO/CNT/SP/KS/PVDF (80/0.3/4.85/4.85/10) and LNMO/CNT/SP/KS/PVDF (80/5/2.5/2.5/10) positive plate electrodes were performed by using a high-power Scanning Electron Microscope (SEM) (shown in figures 2, 3 and 4, respectively); the test results show that: the conductive network in the CNT-free electrode is formed entirely by agglomeration of the SP particles of the conductive agent, and the contact between the SP particle agglomerates and the LNMO particles is poor (fig. 2); the proper amount of CNT added into the composite electrode can be uniformly wound on the surface of LNMO particles and is connected with the conductive agent SP and the conductive graphite KS to form a good conductive network (figure 3); when the CNT is added in excess in the composite electrode, the CNT is tightly coated on the surface of the LNMO particle (fig. 4), which hinders the exertion of electrochemical activity.
(2) Packaging and testing of button half-cells
Step one: packaging
The high-voltage electrolyte prepared in example 1, the positive electrode sheet electrode, the lithium sheet, the polypropylene/polyethylene composite porous film, and the LIR2025 battery case were packaged into a button half cell in a glove box in which oxygen (< 1 ppm) and moisture (< 1 ppm) were controlled.
Step two: testing
a. Cyclic voltammetry test: the half cell of the LNMO/CNT/SP/KS/PVDF (80/0.3/4.85/4.85/10) positive plate packaged in the step one is in the voltage range of 2.80-4.95V, and 0.1mVs -1 Cyclic voltammetry testing (as shown in figure 5) was performed at the scan rate of (c); the test results show that: three pairs of redox peaks appear at 4.07V, 4.77V, 4.83V, corresponding to Mn of LNMO, respectively 3+ /Mn 4+ 、Ni 2+ /Ni 3+ 、Ni 3+ /Ni 4+ Indicating that LNMO has excellent electrochemistry in the high voltage electrolytePerformance.
b. Multiplying power test: and (3) performing constant current charge and discharge test on the half battery packaged in the step one within a voltage range of 3.5-4.95V, wherein the test steps are as follows: 0.5C charging, 0.5C, 1C, 3C, 5C, 8C, 10C, 15C, 20C discharging (as shown in FIG. 6); the test results show that: compared with the positive plate containing 0% CNT and 5% CNT, the positive plate containing 0.3% CNT has higher first 0.5C discharge capacity (0% CNT:117 mAhg) -1 ；0.3%CNT：125mAhg -1 ；5%CNT：93mAhg -1 ) And has a high 20C capacity retention (0% cnt:12.4%;0.3% cnt:75%;5% cnt:1.3 percent) shows that the good conductive network (shown in the figure 3) formed by carrying out composite modification on a certain amount of CNTs and the LNMO material can greatly improve the multiplying power performance of the LNMO.
Example 3
The invention relates to preparation and test of a negative plate of a high-voltage hybrid lithium ion supercapacitor.
1. Preparation of high-voltage hybrid lithium ion supercapacitor negative plate
(1) Preparation of AC/SP/SBR/CMC (90/5/3/2) pole piece
Step one: accurately weighing sodium carboxymethylcellulose (CMC) powder with certain mass, adding ultrapure water with certain mass, putting a magnet with the length of 2cm, sealing the mouth of the beaker by using a plastic film and a rubber ring, placing the beaker on a magnetic stirrer, setting the rotating speed to be 100r/min, and stirring for 12 hours at room temperature to obtain CMC aqueous solution with the mass fraction of 1%; accurately weighing 1% CMC aqueous solution with certain mass, adding into a vacuum stirring tank, then adding 50% Styrene Butadiene Rubber (SBR) aqueous solution with certain mass, setting the rotation speed of a vacuum stirrer to be 500r/min, and stirring for 30min at room temperature to obtain a mixed solution of CMC and SBR; adding Active Carbon (AC) powder with certain mass, and stirring for 90min to obtain AC, CMC, SBR mixed slurry; adding a certain mass of conductive carbon black (SP), and stirring for 60min to obtain the anode material electrode slurry with the mass part ratio of AC/SP/SBR/CMC of 90:5:3:2, wherein the anode material electrode slurry is uniformly dispersed.
Step two: vacuumizing the electrode slurry of the negative electrode material, standing for 10min, filtering by a 100-mesh filter screen, and coating the electrode slurry on an aluminum foil current collector according to a certain thickness; and (3) vacuum drying the obtained pole piece at 60 ℃ for 3-6 hours, rolling according to a rolling ratio of 20%, slicing the rolled pole piece by using a slicer to obtain a round pole piece with the diameter of 12mm, and vacuum drying at 60 ℃ for 10-12 hours to obtain the negative pole piece electrode of the high-voltage hybrid lithium ion supercapacitor.
(2) Preparation of AC/CNT/SP/SBR/CMC (90/0.625/4.375/3/2) pole pieces
Step one: accurately weighing sodium carboxymethylcellulose (CMC) powder with certain mass, adding ultrapure water with certain mass, putting a magnet with the length of 2cm, sealing the mouth of the beaker by using a plastic film and a rubber ring, placing the beaker on a magnetic stirrer, setting the rotating speed to be 100r/min, and stirring for 12 hours at room temperature to obtain CMC aqueous solution with the mass fraction of 1%; accurately weighing 1% CMC aqueous solution with certain mass, adding into a vacuum stirring tank, then adding 50% Styrene Butadiene Rubber (SBR) aqueous solution with certain mass, setting the rotation speed of a vacuum stirrer to be 500r/min, and stirring for 30min at room temperature to obtain a mixed solution of CMC and SBR; adding Carbon Nano Tube (CNT) with certain mass, stirring for 30min to obtain a CNT, CMC, SBR mixed solution; adding Active Carbon (AC) powder with certain mass, and stirring for 90min to obtain AC, CNT, CMC, SBR mixed slurry; adding a certain mass of conductive carbon black (SP), and stirring for 60min to obtain the anode material electrode slurry with the mass part ratio of the AC/CNT/SP/SBR/CMC of 90:0.625:4.375:3:2, wherein the anode material electrode slurry is uniformly dispersed.
Step two: and (3) preparing a pole piece by the electrode slurry of the negative electrode material according to the method of the step (1) in the embodiment 3, so as to prepare the negative electrode piece of the high-voltage hybrid lithium ion supercapacitor.
(3) Preparation of AC/CNT/SBR/CMC (90/5/3/2) pole piece
Step one: accurately weighing sodium carboxymethylcellulose (CMC) powder with certain mass, adding ultrapure water with certain mass, putting a magnet with the length of 2cm, sealing the mouth of the beaker by using a plastic film and a rubber ring, placing the beaker on a magnetic stirrer, setting the rotating speed to be 100r/min, and stirring for 12 hours at room temperature to obtain CMC aqueous solution with the mass fraction of 1%; accurately weighing 1% CMC aqueous solution with certain mass, adding into a vacuum stirring tank, then adding 50% Styrene Butadiene Rubber (SBR) aqueous solution with certain mass, setting the rotation speed of a vacuum stirrer to be 500r/min, and stirring for 30min at room temperature to obtain a mixed solution of CMC and SBR; adding Carbon Nano Tube (CNT) with certain mass, stirring for 30min to obtain a CNT, CMC, SBR mixed solution; adding Active Carbon (AC) powder with certain mass, stirring for 90min, and obtaining the anode material electrode slurry with the mass part ratio of the AC/CNT/SBR/CMC being 90:5:3:2.
Step two: and (3) preparing a pole piece by the electrode slurry of the negative electrode material according to the method of the step (1) in the embodiment 3, so as to prepare the negative electrode piece of the high-voltage hybrid lithium ion supercapacitor.
2. Testing of high-voltage hybrid lithium ion supercapacitor negative plate
(1) High power Scanning Electron Microscope (SEM) testing
Characterization tests of the morphology of the AC/SP/SBR/CMC (90/5/3/2), AC/CNT/SP/SBR/CMC (90/0.625/4.375/3/2) and AC/CNT/SBR/CMC (90/5/3/2) negative plate electrodes were performed by using a high-power Scanning Electron Microscope (SEM) (shown in figures 7, 8 and 9, respectively); the test results show that: the conductive network in the CNT-free electrode is formed entirely by agglomeration of the SP particles of the conductive agent, and the contact between the SP particle agglomerates and the AC particles is poor (fig. 7); the CNT added in the composite electrode can be uniformly wound on the surface of the AC particles and connected with the conductive agent SP to form a good conductive network (fig. 8); when the CNT is added in excess in the composite electrode, the CNT is tightly coated on the surface of the AC particle (fig. 9), which hinders the exertion of electrochemical activity.
(2) Packaging and testing of button half-cells
Step one: packaging
The high-voltage electrolyte prepared in example 1, the negative electrode sheet electrode, the lithium sheet, the polypropylene/polyethylene composite porous film, and the LIR2025 battery case were packaged into a button half cell in a glove box in which oxygen (< 1 ppm) and moisture (< 1 ppm) were controlled.
Step two: testing
a. Cyclic voltammetry test: the half cell of the negative plate of the step one packaged AC/CNT/SP/SBR/CMC (90/0.625/4.375/3/2) is in the voltage range of 1.3-3.6V, and 5mVs is used -1 Cyclic voltammetry testing (as shown in fig. 10) was performed at the scan rate of (a); the test results show that: the AC shows an obvious rectangular cyclic voltammetry curve within a voltage range of 1.3-3.6V, which shows that the AC has excellent electric double layer capacitance characteristics within a wider voltage range of the high-voltage electrolyte.
b. Multiplying power test: and (3) performing constant current charge and discharge test on the half battery packaged in the step one within a voltage range of 1.5-3.0V, wherein the current densities are respectively set as follows: 0.015Ag -1 、0.03Ag -1 、0.06Ag -1 、0.12Ag -1 、0.24Ag -1 、0.48Ag -1 、0.96Ag -1 、1.92Ag -1 (as shown in FIG. 11); the test results show that: the negative electrode sheet containing 0.625% CNT has higher 1.92Ag than the negative electrode sheet containing 0% CNT and 5% CNT -1 The capacity retention (0% CNT:28.4%, 0.625% CNT:38.6%, 5% CNT: 21.9%) indicates that the good conductive network (shown in figure 8) formed by compounding and modifying a certain amount of CNT with the AC material can greatly improve the rate capability of the AC.
Example 4
The invention relates to a packaging and testing method of a high-voltage hybrid lithium ion supercapacitor.
Step one: packaging
In a glove box with oxygen (< 1 ppm) and moisture (< 1 ppm) control, the high voltage electrolyte prepared in example 1, the LNMO/CNT/SP/KS/PVDF (80/0.3/4.85/4.85/10) positive plate electrode prepared in example 2, the AC/CNT/SP/SBR/CMC (90/0.625/4.375/3/2) negative plate electrode prepared in example 3, and the polypropylene/polyethylene composite porous film, LIR2025 battery case were packaged into a button capacitor. Wherein the capacity ratio of the positive electrode to the negative electrode is 3.5:1.
Step two: testing
a. Cyclic voltammetry test: the buckle capacitor packaged in the step one is set at a voltage of 0-3.5VWithin a range of 1mVs -1 Cyclic voltammetric testing (as shown in fig. 12) was performed at the scan rate of (a); the test results show that: the mixed lithium ion supercapacitor prepared by packaging the high-voltage electrolyte, the nano-carbon composite modified LNMO anode and the nano-carbon composite modified AC cathode has higher working voltage (reaching 3.5V), and the cyclic voltammetry characteristic (figure 12) is a combination of the cyclic voltammetry characteristics of the anode (figure 5) and the cathode (figure 10) of the capacitor; the obtained hybrid lithium ion super capacitor well maintains the oxidation-reduction electrochemical performance of the anode of the battery and the electric double layer capacitance characteristic of the cathode of the capacitor, so that the hybrid lithium ion super capacitor has higher power density and higher energy density than the lithium ion battery.
b. Multiplying power test: carrying out constant current charge and discharge test on the packaged button capacitor in the step one within the voltage range of 0-3.45V, and setting the current densities as follows: 0.015Ag -1 、0.03Ag -1 、0.06Ag -1 、0.12Ag -1 、0.24Ag -1 、0.48Ag -1 、0.96Ag -1 、1.92Ag -1 、2Ag -1 、4Ag -1 、6Ag -1 、8Ag -1 、10Ag -1 、12Ag -1 、15Ag -1 、20Ag -1 、22Ag -1 、24Ag -1 、26Ag -1 、28Ag -1 (as shown in FIG. 17); the test results show that: the hybrid lithium ion supercapacitor has higher maximum energy density (56 Whkg -1 ) And maximum power density (21 kWkg) -1 ）。
c. Cycle life test: carrying out constant current charge and discharge cycle test on the packaged button capacitor in the step one within the voltage range of 0-3.45V, wherein the current density is set to be 5C (shown in figure 13); the test results show that: in the charge-discharge cycle process, the hybrid lithium ion supercapacitor has higher coulomb efficiency (100%); after 4500 cycles, a higher capacity retention (98%) is maintained.
LNMO/CNT/SP/KS/PVDF (80/0.3/4.85/4.85/10) positive plate electrodes with different thicknesses prepared in example 2 and AC/CNT/SP/SBR/CMC (90/0.625/4.375/3/2) negative plate electrodes with different thicknesses prepared in example 3 are selected according to different positive electrode-to-negative electrode capacity ratios, and the button type hybrid lithium ion supercapacitor is packaged and tested according to the method. The results are shown in Table 1.
Table 1 Performance of high voltage hybrid lithium ion super capacitor tested in the 0-3.45V voltage range
Comparative example 1
Preparation and testing of electrodes (positive/negative plates) and capacitors of conventional symmetrical double layer super capacitors.
(1) Preparation of AC/SP/SBR/CMC (90/5/3/2) pole piece
Step one: accurately weighing sodium carboxymethylcellulose (CMC) powder with certain mass, adding ultrapure water with certain mass, putting a magnet with the length of 2cm, sealing the mouth of the beaker by using a plastic film and a rubber ring, placing the beaker on a magnetic stirrer, setting the rotating speed to be 100r/min, and stirring for 12 hours at room temperature to obtain CMC aqueous solution with the mass fraction of 1%; accurately weighing 1% CMC aqueous solution with certain mass, adding the solution into a vacuum stirring tank, then adding 50% SBR aqueous solution with certain mass, setting the rotating speed of a vacuum stirrer to be 500r/min, and stirring for 30min at room temperature to obtain a mixed solution of CMC and SBR; adding Active Carbon (AC) powder with certain mass, and stirring for 90min to obtain AC, CMC, SBR mixed slurry; adding a certain mass of conductive carbon black (SP), and stirring for 60min to obtain the uniformly dispersed electrode slurry with the mass part ratio of AC/SP/SBR/CMC of 90:5:3:2.
Step two: vacuumizing the electrode slurry, standing for 10min, filtering by a 100-mesh filter screen, and coating the electrode slurry on an aluminum foil current collector according to a certain thickness; and (3) vacuum drying the obtained pole piece at 60 ℃ for 3-6 hours, rolling according to a rolling ratio of 20%, slicing the rolled pole piece by using a slicer to obtain a round pole piece with the diameter of 12mm, and vacuum drying at 60 ℃ for 10-12 hours to obtain the electrode (positive pole piece/negative pole piece) of the conventional symmetrical double-layer supercapacitor.
Step three: carrying out characterization test of morphological characteristics on the electrode slice by using a high-power Scanning Electron Microscope (SEM) (shown in figure 14); the test results show that: the conductive network in the resulting electrode is formed entirely by the agglomeration of the SP particles of the conductive agent, and the contact between the SP particle agglomerates and the AC particles is poor.
(2) Encapsulation and testing of conventional symmetrical double-layer supercapacitor
Step one: packaging
In the control of oxygen<1 ppm) and moisture%<1 ppm) of the above electrode (positive electrode sheet/negative electrode sheet), and 1mol L -1 [TEA][BF 4 ]ACN electrolyte, cellulose acetate diaphragm, LIR2025 battery case, encapsulate into button capacitor; wherein the capacity ratio of the positive electrode to the negative electrode is 1:1.
Step two: testing
a. Cyclic voltammetry test: the buckle capacitor packaged in the step one is in the voltage range of 0-2.7V, and 5mVs is adopted -1 Cyclic voltammetry testing (as shown in fig. 15) was performed at the scanning speed of (a); the test results show that: the capacitor exhibits a pronounced rectangular cyclic voltammogram, indicating its typical electric double layer capacitance characteristics.
b. Multiplying power test: and (3) performing constant current charge and discharge test on the packaged button capacitor in the step one within a voltage range of 0-2.7V, wherein the current density is set as follows: 0.5Ag -1 、1Ag -1 、2Ag -1 、4Ag -1 、8Ag -1 、10Ag -1 、15Ag -1 、20Ag -1 、30Ag -1 (as shown in FIG. 17); the test results show that: the maximum energy density and the maximum power density of the conventional symmetrical double-layer super capacitor are respectively 25Whkg -1 And 32kWkg -1 。
c. Cycle life test: carrying out constant current charge and discharge cyclic test on the packaged button capacitor in the step one within the voltage range of 0-2.7V, and setting the current density to 10Ag -1 (as shown in fig. 16); the test results show that: after 4500 cycles, the conventional pairThe double-layer supercapacitor is said to have reasonable coulombic efficiency (94%) and capacity retention (91%).
Comparative analysis
According to the invention, the nano carbon material is introduced to respectively carry out composite modification on the 5V anode material and the porous carbon material. In the obtained nano composite electrode material, the nano carbon material is uniformly wound (coated) on the surface of the 5V positive electrode material or the porous carbon material particles, and is connected with the conductive agent particles to form a good conductive network (figure 3 and figure 8). Compared with the conventional electrode materials (figure 2 and figure 7) which are not compounded by the nano carbon materials, the nano carbon material compound modification technology can improve the conductivity and the multiplying power performance (figure 6 and figure 11) of the 5V positive electrode material and the porous carbon negative electrode material, thereby improving the power characteristic, the safety and the cycle service life of the obtained mixed lithium ion super capacitor.
According to the invention, the nano carbon material composite modified 5V positive electrode material positive electrode and the porous carbon material negative electrode are combined, so that the prepared mixed lithium ion supercapacitor well maintains the redox electrochemical performance of the battery positive electrode (shown in figure 5) and the electric double layer capacitance characteristic of the capacitor negative electrode (shown in figure 10), and therefore has higher power density and higher energy density than those of a lithium ion battery. The capacity ratio of the positive electrode to the negative electrode is optimized, so that the charge and discharge processes can be better matched, the working voltage (shown in figure 12) of the obtained hybrid lithium ion supercapacitor is obviously improved compared with that of a conventional symmetrical double-layer supercapacitor (shown in figure 15), and the energy density and the power density (shown in figure 17) of the hybrid lithium ion supercapacitor are obviously improved.
According to the invention, the organic solvent suitable for the high-voltage electrolyte, the lithium salt electrolyte suitable for the high-voltage electrolyte and the electrolyte additive capable of stabilizing the high-voltage positive electrode material are selected, so that the obtained high-voltage electrolyte has a wider safe electrochemical window, and the additive can be oxidized on the surface of an electrode to form an effective protective film (figure 1), so that the obtained hybrid lithium ion supercapacitor has higher working voltage, better safety and longer cycle service life (figure 13).
In conclusion, the high-voltage hybrid lithium ion supercapacitor disclosed by the invention has higher working voltage, energy density, power density, safety and cycle service life.

Claims (1)

1. The high-voltage hybrid lithium ion supercapacitor comprises a positive plate, a negative plate, a diaphragm between the positive plate and the negative plate, electrolyte filled in gaps between the positive plate and the negative plate and a diaphragm, and a shell, wherein the positive plate and/or the negative plate consists of a current collector and an electrode material coated on the surface of the current collector and comprising a nano carbon material, the electrode material of the positive plate consists of a 5V positive electrode material, a nano carbon material, a conductive agent and a binder, and the electrode material of the negative plate consists of a porous carbon material, a nano carbon material, a conductive agent and a binder, and is characterized in that the high-voltage hybrid lithium ion supercapacitor is prepared by the following steps:
(1) Containing 1mol L -1 LiPF 6 Preparation of 0.2% TPPi EC DMC EMC high voltage electrolyte
In controlling oxygen<1ppm and moisture<In a glove box with the concentration of 1ppm, uniformly mixing and stirring selected organic solvents of Ethylene Carbonate (EC), dimethyl carbonate (DMC) and methyl ethyl carbonate (EMC) according to the volume ratio of 1:1:1 to obtain a required mixed solvent; accurately weighing a certain mass of lithium salt lithium hexafluorophosphate (LiPF) 6 ) Adding triphenyl phosphite (TPPi) as additive into the mixed solvent, dissolving, stirring, adding a certain amount of molecular sieve, standing for 24 hr to obtain a solution containing 1mol - 1 LiPF 6 And 0.2% tppi of a high voltage electrolyte;
(2) Preparation of LNMO/CNT/SP/KS/PVDF positive plate
Step one: accurately weighing a certain mass of polyvinylidene fluoride (PVDF) powder, adding the polyvinylidene fluoride (PVDF) powder into a vacuum stirring tank, and then adding a certain mass of N-methylpyrrolidone (NMP), wherein PVDF is obtained: the mass ratio of NMP is 1:20, setting the rotating speed of a vacuum stirrer to 500r/min, stirring for 60min at room temperature, and obtaining the PVDF and NMP mixtureMixing the solutions; adding Carbon Nano Tube (CNT) with certain mass, stirring for 60min to obtain a CNT, PVDF, NMP mixed solution; adding 5V positive electrode material LiNi with certain mass 0.5 Mn 1.5 O 4 (LNMO) and stirring for 90min to obtain LNMO, CNT, PVDF, NMP mixed slurry; respectively adding conductive carbon black (SP) and conductive graphite (KS) with certain mass, stirring for 60min, and preparing anode material electrode slurry with the mass part ratio of LNMO/CNT/SP/KS/PVDF of 80:0.3:4.85:4.85:10, wherein the LNMO/CNT/SP/KS/PVDF is uniformly dispersed;
step two: vacuumizing the positive electrode material electrode slurry, standing for 10min, filtering by a 120-mesh filter screen, and coating the positive electrode material electrode slurry on an aluminum foil current collector according to a certain thickness to obtain a pole piece; vacuum drying the obtained pole piece for 3-6 hours at 80 ℃, and then rolling according to a rolling ratio of 36%; then slicing the rolled pole piece by using a slicer to obtain a round pole piece with the diameter of 12mm, and then vacuum drying at 120 ℃ for 10-12 h to obtain the positive pole piece electrode of the high-voltage hybrid lithium ion supercapacitor;
(3) Preparation of AC/CNT/SP/SBR/CMC negative plate
Step one: accurately weighing sodium carboxymethylcellulose (CMC) powder with certain mass, adding ultrapure water with certain mass, putting a magnet with the length of 2cm, sealing the mouth of the beaker by using a plastic film and a rubber ring, placing the beaker on a magnetic stirrer, setting the rotating speed to be 100r/min, and stirring for 12 hours at room temperature to obtain CMC aqueous solution with the mass fraction of 1%; accurately weighing 1% CMC aqueous solution with certain mass, adding into a vacuum stirring tank, then adding 50% Styrene Butadiene Rubber (SBR) aqueous solution with certain mass, setting the rotation speed of a vacuum stirrer to be 500r/min, and stirring for 30min at room temperature to obtain a mixed solution of CMC and SBR; adding Carbon Nano Tube (CNT) with certain mass, stirring for 30min to obtain a CNT, CMC, SBR mixed solution; adding Active Carbon (AC) powder with certain mass, and stirring for 90min to obtain AC, CNT, CMC, SBR mixed slurry; adding conductive carbon black (SP) with certain mass, stirring for 60min to obtain anode material electrode slurry with the mass part ratio of AC/CNT/SP/SBR/CMC of 90:0.625:4.375:3:2, wherein the anode material electrode slurry is uniformly dispersed;
step two: vacuumizing the electrode slurry of the negative electrode material, standing for 10min, filtering by a 100-mesh filter screen, and coating the electrode slurry on an aluminum foil current collector according to a certain thickness; vacuum drying the obtained pole piece for 3-6 h at 60 ℃, rolling according to a rolling ratio of 20%, slicing the rolled pole piece by using a slicing machine to obtain a round pole piece with the diameter of 12mm, and vacuum drying at 60 ℃ for 10-12 h to obtain a negative pole piece electrode of the high-voltage hybrid lithium ion supercapacitor;
(4) Packaging of high-voltage hybrid lithium ion supercapacitor
In a glove box for controlling oxygen to be less than 1ppm and moisture to be less than 1ppm, packaging the high-voltage electrolyte prepared in the step (1), the LNMO/CNT/SP/KS/PVDF positive plate electrode prepared in the step (2), the AC/CNT/SP/SBR/CMC negative plate electrode prepared in the step (3), a polypropylene/polyethylene composite porous film and a LIR2025 battery shell into a button capacitor;
according to different anode-to-cathode capacity ratios, LNMO/CNT/SP/KS/PVDF anode plate electrodes with different thicknesses and AC/CNT/SP/SBR/CMC anode plate electrodes with different thicknesses are selected, and the button type hybrid lithium ion super capacitor prepared by the method shows the performances shown in the following table,
。
CN202210344177.8A 2018-10-15 2018-10-15 High-voltage hybrid lithium ion supercapacitor and preparation method thereof Active CN114743803B (en)

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