CN109961959B - Calcium ion mixed super capacitor and preparation method thereof - Google Patents
Calcium ion mixed super capacitor and preparation method thereof Download PDFInfo
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- CN109961959B CN109961959B CN201711440242.2A CN201711440242A CN109961959B CN 109961959 B CN109961959 B CN 109961959B CN 201711440242 A CN201711440242 A CN 201711440242A CN 109961959 B CN109961959 B CN 109961959B
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES OR LIGHT-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
- H01G11/04—Hybrid capacitors
- H01G11/06—Hybrid capacitors with one of the electrodes allowing ions to be reversibly doped thereinto, e.g. lithium ion capacitors [LIC]
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES OR LIGHT-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
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- 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
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/13—Energy storage using capacitors
Abstract
The invention discloses a calcium ion hybrid super capacitor and a preparation method thereof, and relates to the field of electrochemical energy storage devices. The calcium ion mixed super capacitor comprises a negative electrode, a positive electrode, a diaphragm between the positive electrode and the negative electrode and electrolyte; the negative electrode is metal, metal alloy or metal compound capable of alloying with calcium ions; the positive electrode comprises a positive current collector and a positive material; the active substance of the positive electrode material is a carbon material capable of reversibly adsorbing and desorbing anions in the electrolyte; the electrolyte includes a calcium salt and a non-aqueous solvent. According to the invention, calcium ions are used as active carriers, a metal material capable of performing an alloying reaction with calcium is used as a negative electrode active material and a current collector under the system, and a carbon material is used as a positive electrode active material, so that the obtained hybrid supercapacitor combines the advantages of high energy density of a calcium ion battery and high capacity density of the supercapacitor, and the calcium ion hybrid supercapacitor has high energy density and high capacity density.
Description
Technical Field
The invention relates to the technical field of electrochemical energy storage devices, in particular to a calcium ion hybrid supercapacitor and a preparation method thereof.
Background
The hybrid super capacitor is a novel energy storage system combining high energy density of a secondary battery, high power density of a capacitor, long cycle life and excellent quick charging performance of the capacitor, and comprises a capacitor electrode, a secondary battery electrode, organic electrolyte and a diaphragm. Due to the advantages of high specific capacity of the active material of the secondary battery, wide voltage window of the organic electrolyte and the like, compared with the conventional super capacitor, the hybrid super capacitor has higher energy density.
At present, a hybrid supercapacitor is generally based on lithium ions and has two configurations, wherein one configuration adopts a positive electrode material (such as lithium cobaltate, lithium iron phosphate, ternary and the like) of a lithium ion battery and a negative electrode material of a capacitor, such as activated carbon, mesoporous carbon and the like with large specific surface area; the other adopts the lithium ion battery cathode material (such as Li)2TiO3Graphite, etc.), and a capacitor positive electrode material such as activated carbon or mesoporous carbon having a large specific surface area. The super capacitor with the two structures is prepared in the processThe preparation process is complicated, the labor and equipment investment is large, meanwhile, a lithium-containing material is inevitably used, and lithium has the characteristics of low natural abundance and high activity, so that the hybrid super capacitor is high in manufacturing cost and poor in safety performance.
In order to improve the energy density of the capacitor, the lithium ion hybrid super capacitor adopts Li4Ti5O12Graphite materials, metal oxides and the like are used as the negative electrode of the lithium ion hybrid supercapacitor. However, the lithium titanate and the metal oxide are used as the negative electrode active material, and the disadvantages of complex production process, serious environmental pollution and high production cost are encountered. And graphite materials are adopted as the negative electrode materials, although the preparation cost is low and the storage capacity is large, the specific capacity and compaction of graphite are low, and the improvement of the energy density of the hybrid super capacitor is limited. The existing lithium ion-based hybrid super capacitor has limited improvement degrees on the manufacturing cost, safety, energy density, capacity and other performances of the capacitor, and cannot meet the current requirements on the capacitor.
In view of the above, the present invention is particularly proposed.
Disclosure of Invention
One of the purposes of the invention is to provide a calcium ion hybrid supercapacitor, which adopts calcium ions as active carriers, adopts metal materials capable of performing alloying reaction with calcium as negative active materials and current collectors under the system, adopts carbon materials as positive active materials, can provide higher capacity and higher energy density through the alloying reaction of the metal materials and the calcium, combines the advantages of high energy density of a calcium ion battery and high capacity density of a supercapacitor, and has high energy density and high capacity density.
The invention also aims to provide a preparation method of the calcium ion hybrid supercapacitor, the calcium ion hybrid supercapacitor is assembled by utilizing the negative electrode, the electrolyte, the diaphragm and the positive electrode, and the preparation method is simple.
In order to achieve the above purpose of the present invention, the following technical solutions are adopted:
a calcium ion hybrid super capacitor comprises a negative electrode, a positive electrode, a diaphragm between the positive electrode and the negative electrode and electrolyte;
the negative electrode is a metal, a metal alloy or a metal compound capable of alloying with calcium ions;
the positive electrode comprises a positive current collector and a positive material; the active substance of the positive electrode material is a carbon material capable of reversibly adsorbing and desorbing anions in the electrolyte;
the electrolyte includes a calcium salt and a non-aqueous solvent.
Preferably, on the basis of the technical scheme of the invention, the negative electrode is any one metal of tin, aluminum, copper, iron, zinc, nickel, titanium, manganese, magnesium or antimony; or the like, or, alternatively,
the negative electrode is an alloy at least containing any one of tin, aluminum, copper, iron, zinc, nickel, titanium, manganese, magnesium or antimony; or the like, or, alternatively,
the negative electrode is a compound at least containing any one of tin, aluminum, copper, iron, zinc, nickel, titanium, manganese, magnesium or antimony;
preferably, the negative electrode is tin, a tin alloy or a tin-containing composite.
Preferably, on the basis of the technical scheme of the invention, the carbon material is any one of granular activated carbon, powdered activated carbon, graphene, mesocarbon microbeads, three-dimensional ordered mesoporous carbon spheres, activated carbon fibers, activated carbon felt, activated carbon cloth, template skeleton carbon, carbide-derived carbon, carbon nanotubes, carbon aerogel, glassy carbon, nano charcoal or carbon foam; or the like, or, alternatively,
the carbon material is a composite material at least comprising any one of granular activated carbon, powdered activated carbon, graphene, mesocarbon microbeads, three-dimensional ordered mesoporous carbon spheres, activated carbon fibers, activated carbon felts, activated carbon cloth, template skeleton carbon, carbide derived carbon, carbon nanotubes, carbon aerogel, glassy carbon, nano charcoal or carbon foam;
preferably, the carbon material is granular activated carbon.
Preferably, on the basis of the technical scheme of the invention, the positive current collector is a metal selected from any one of aluminum, copper, iron, tin, zinc, nickel, titanium or manganese; or the like, or, alternatively,
the positive current collector is an alloy at least containing any one of aluminum, copper, iron, tin, zinc, nickel, titanium or manganese; or the like, or, alternatively,
the positive electrode current collector is a compound at least containing any one of aluminum, copper, iron, tin, zinc, nickel, titanium or manganese.
Preferably, on the basis of the technical scheme of the invention, the positive electrode material comprises 60-96 wt% of positive electrode material active substance, 1-30 wt% of conductive agent and 3-10 wt% of binder;
preferably, the conductive agent comprises one or at least two of conductive carbon black, conductive carbon spheres, conductive graphite, carbon nanotubes, conductive carbon fibers, graphene or reduced graphene oxide, preferably conductive carbon black;
preferably, the binder comprises one or at least two of polyvinylidene fluoride, polytetrafluoroethylene, polyvinyl alcohol, carboxymethyl cellulose, SBR rubber or polyolefins, preferably polyvinylidene fluoride.
Preferably, on the basis of the technical scheme of the invention, the concentration of the calcium salt in the electrolyte is 0.1-10mol/L, preferably 0.1-2 mol/L;
preferably, the calcium salt comprises one or at least two of calcium hexafluorophosphate, calcium tetrafluoroborate, calcium chloride, calcium carbonate, calcium sulfate, calcium nitrate, calcium fluoride, calcium trifluoromethanesulfonate, calcium bis (trifluoromethylsulfonyl) imide, calcium bis fluorosulfonyl imide or calcium perchlorate, preferably calcium hexafluorophosphate.
Preferably, on the basis of the technical scheme of the invention, the nonaqueous solvent is an organic solvent and/or an ionic liquid;
preferably, the organic solvent comprises one or at least two of ester, sulfone, ether, nitrile or olefin organic solvents; and/or the presence of a gas in the gas,
the ionic liquid comprises one or at least two of imidazole, piperidine, pyrrole, quaternary ammonium or amide ionic liquids;
preferably, the organic solvent includes one or at least two of propylene carbonate, ethylene carbonate, diethyl carbonate, dimethyl carbonate, ethyl methyl carbonate, methyl formate, methyl acetate, N-dimethylacetamide, fluoroethylene carbonate, methyl propionate, ethyl acetate, γ -butyrolactone, tetrahydrofuran, 2-methyltetrahydrofuran, 1, 3-dioxolane, 4-methyl-1, 3-dioxolane, dimethoxymethane, 1, 2-dimethoxypropane, triethylene glycol dimethyl ether, dimethyl sulfone, dimethyl ether, ethylene sulfite, propylene sulfite, dimethyl sulfite, diethyl sulfite, or crown ether, preferably a mixed solvent of ethylene carbonate, propylene carbonate, dimethyl carbonate, and ethyl methyl carbonate;
preferably, the ionic liquid comprises 1-ethyl-3-methylimidazole-hexafluorophosphate, 1-ethyl-3-methylimidazole-tetrafluoroborate, 1-ethyl-3-methylimidazole-bistrifluoromethylsulfonyl imide salt, 1-propyl-3-methylimidazole-hexafluorophosphate, 1-propyl-3-methylimidazole-tetrafluoroborate, 1-propyl-3-methylimidazole-bistrifluoromethylsulfonyl imide salt, 1-butyl-1-methylimidazole-hexafluorophosphate, 1-butyl-1-methylimidazole-tetrafluoroborate, 1-butyl-1-methylimidazole-bistrifluoromethylsulfonyl imide salt, 1-ethyl-3-methylimidazole-tetrafluoroborate, 1-butyl-1-methylimidazole-bistrifluoromethylsulfonyl imide salt, a salt thereof, a salt, One or at least two of N-butyl-N-methylpyrrolidine-bis-trifluoromethylsulfonyl imide salt, 1-butyl-1-methylpyrrolidine-bis-trifluoromethylsulfonyl imide salt, N-methyl-N-propylpyrrolidine-bis-trifluoromethylsulfonyl imide salt, N-methyl, propylpiperidine-bis-trifluoromethylsulfonyl imide salt, or N-methyl, butylpiperidine-bis-trifluoromethylsulfonyl imide salt.
Further, on the basis of the technical scheme of the invention, the electrolyte also comprises an additive;
the mass fraction of the additive in the electrolyte is 0.1-20%, preferably 2-5%;
preferably, the additive comprises one or at least two of ester, sulfone, ether, nitrile or olefin organic additives.
According to the preparation method of the calcium ion mixed super capacitor, the negative electrode, the electrolyte, the diaphragm and the positive electrode are assembled to obtain the calcium ion mixed super capacitor.
Preferably, on the basis of the technical scheme of the invention, the preparation method of the calcium ion mixed supercapacitor comprises the following steps:
a) preparing a negative electrode: treating the surface of the metal, alloy or metal compound with required size to serve as a negative electrode for later use;
b) preparing an electrolyte: dissolving calcium salt in a non-aqueous solvent, and fully mixing to obtain an electrolyte;
c) preparing a diaphragm: cutting a porous polymer film, an inorganic porous film or an organic/inorganic composite membrane into a required size to be used as a membrane;
d) preparing a positive electrode: adding the active substance of the positive electrode material, the conductive agent and the binder into a solvent according to a certain proportion, and fully mixing to form positive electrode material slurry; uniformly coating the positive electrode material slurry on the surface of a positive electrode current collector to form a positive electrode active material layer, drying, pressing and cutting into pieces to obtain a positive electrode with a required size;
assembling the negative electrode obtained in the step a), the electrolyte obtained in the step b), the diaphragm obtained in the step c) and the positive electrode obtained in the step d) to obtain the calcium ion mixed super capacitor.
Compared with the prior art, the invention has the following beneficial effects:
(1) the hybrid super capacitor is a calcium ion hybrid super capacitor, divalent calcium ions are used as active carriers, the capacity of the calcium ion hybrid super capacitor is twice that of lithium ions in each molar calcium ion reaction, the traditional lithium is replaced by calcium, the problem of limited lithium resource storage capacity is solved, and the hybrid super capacitor is environment-friendly and can avoid pollution compared with a lithium ion energy storage device.
(2) The calcium ion mixed super capacitor adopts the carbonaceous material as the active substance of the anode material, has wide material source and low price, does not generate chemical reaction when in work, and has higher power density and longer service life under a calcium ion system. The metal foil capable of performing alloying reaction with calcium is used as a negative active material and a negative current collector simultaneously to play double roles of conducting and reacting, so that two elements of a negative active material and a negative current collector of a conventional super capacitor negative electrode are omitted, compared with the prior art that the negative electrode of a super capacitor usually comprises the current collector with the conducting function and the active material for reacting, the volume and the weight of one part are saved, the device manufacturing process is simplified, the active material occupation ratio is increased, and higher energy density can be obtained. The integrated design of the cathode material and the current collector is beneficial to reducing the calcium ion transmission distance and realizing more effective mass transfer/charge transfer. The obtained hybrid super capacitor combines the advantages of high energy density of the calcium ion battery and high capacity density of the super capacitor, and has high energy density and high capacity density at the same time.
(3) The hybrid super capacitor has a simple structure, avoids the adoption of lithium-containing compounds with relatively few resources, has rich metal reserves of the negative electrode, is low in price and environment-friendly, and effectively reduces the manufacturing cost of the hybrid super capacitor.
(4) The calcium ion mixed super capacitor has rich electrolyte calcium salt reserves and low price, reduces the cost of the mixed super capacitor, does not generate dendrite to pierce a diaphragm in the reaction process, and has better safety performance.
Drawings
FIG. 1 is a schematic structural diagram of a calcium ion hybrid supercapacitor according to one embodiment of the present invention;
FIG. 2 is a graph showing the relationship between the time and the charging and discharging voltage at circles 8, 9 and 10 of the calcium ion hybrid supercapacitor according to the present invention.
Icon: 1-a negative electrode; 2-an electrolyte; 3-a separator; 4-positive electrode; 5-a positive electrode material layer; 6-positive electrode current collector.
Detailed Description
Embodiments of the present invention will be described in detail below with reference to examples, but it will be understood by those skilled in the art that the following examples are only illustrative of the present invention and should not be construed as limiting the scope of the present invention. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.
According to one aspect of the invention, a calcium ion hybrid supercapacitor is provided, which comprises a negative electrode, a positive electrode, a diaphragm between the positive electrode and the negative electrode, and electrolyte;
the negative electrode is a metal, a metal alloy or a metal compound capable of alloying with calcium ions;
the positive electrode comprises a positive current collector and a positive material; the active substance of the positive electrode material is a carbon material capable of reversibly adsorbing and desorbing anions in the electrolyte;
the electrolyte includes a calcium salt and a non-aqueous solvent.
As shown in fig. 1, the calcium-ion hybrid supercapacitor of the present invention structurally includes a negative electrode 1, an electrolyte 2, a separator 3, and a positive electrode 4, and the positive electrode 4 includes a positive electrode current collector 6 and a positive electrode material layer 5 thereon.
The invention relates to a calcium ion hybrid super capacitor, which takes calcium ions as active carriers and combines the advantages of high energy density of a calcium ion battery and high capacity density of the super capacitor.
[ negative electrode ]
The cathode of the calcium ion hybrid supercapacitor is a metal, metal alloy or metal composite capable of alloying with calcium ions.
The cathode of the calcium ion hybrid supercapacitor is made of metal, metal alloy or metal compound capable of being alloyed with calcium ions, and the metal, the metal alloy or the metal compound capable of being alloyed with the calcium ions in the electrolyte is a metal capable of being alloyed with the calcium ions in the electrolyte, an alloy capable of being alloyed with the calcium ions in the electrolyte or a metal compound capable of being alloyed with the calcium ions in the electrolyte.
The metal is not limited as long as it can form an alloy with calcium.
Typical but non-limiting metals are tin, aluminum, copper, iron, zinc, nickel, titanium, manganese, magnesium, or antimony, and the like.
Alloy means an alloy of a metal capable of forming an alloy with calcium and one or more other metals.
Typical but non-limiting alloys are iron-tin alloys, titanium-antimony alloys, titanium-aluminum alloys, titanium-magnesium alloys, or the like.
The metal composite refers to a metal matrix composite formed by combining a metal capable of forming an alloy with calcium and other non-metallic materials. Typical, but non-limiting, metal composites include graphene-metal composites, carbon fiber-metal composites, ceramic-metal composites, and the like.
Typical but non-limiting metal composites are tin/graphene composites, nickel/polyaniline composites, and the like.
The metal, metal alloy or metal composite capable of alloying with calcium ions is preferably made into a foil for use as a negative electrode of a calcium ion hybrid supercapacitor.
During charging, Ca is generated during calcium intercalation2+The electrolyte reaches the surface of the cathode metal material, free electrons are obtained on the cathode, calcium atoms are formed and then deposited on the surface of the cathode, and then the calcium atoms are diffused into the cathode material from the surface of the cathode material to generate alloying reaction; on the contrary, during discharging, at high potential, calcium atoms lose electrons on the surface of the negative electrode due to chemical activity to form Ca2+And then, the calcium atoms enter the electrolyte and migrate to the positive electrode under the action of an electric field, and the calcium atoms inside the negative electrode diffuse to the surface of the negative electrode, so that the negative electrode undergoes dealloying (decomposition of the alloy).
The alloying reaction and dealloying reaction can be described as
Reconstruction of the atomic Structure, CaMxThe phase structure of the alloy phase is different from the parent phase M and the reaction involves a change of phase.
During charging, calcium ions in the electrolyte migrate to the surface of the negative electrode under the action of an electric field, and are subjected to a deposition dissolution process or an alloying reaction with metal or alloy or metal compound of the negative electrode to form a calcium-metal alloy, and anions in the electrolyte migrate to the positive electrode and are adsorbed on the surface of the carbon material; during discharging, a reverse deposition dissolution process is carried out or calcium ions enter into the electrolyte through alloying decalcification of the cathode calcium-alloy, and the negative ion groups adsorbed on the surface of the carbon material are desorbed and returned to the electrolyte again, so that the reversible charging and discharging are realized.
The calcium ion hybrid super capacitor provided by the invention uses calcium ions as active carriers, the reaction main body of the generated electrochemical reaction is the calcium ions, and lithium is replaced by calcium, so that the problem of limited lithium resource reserves is solved, and the traditional lithium ion hybrid super capacitor system is changed.
The calcium ion hybrid supercapacitor adopts metal, alloy or metal compound capable of alloying with calcium ions as a negative current collector and a negative material (serving as a negative active material and a negative current collector) of the hybrid supercapacitor, not only has a conductive function, but also serves as an active material reacting with calcium ions.
[ Positive electrode ]
The calcium ion hybrid supercapacitor positive electrode comprises a positive electrode current collector and a positive electrode material; the active material of the positive electrode material is a carbon material capable of reversibly adsorbing and desorbing anions in the electrolyte.
The carbon material includes, but is not limited to, one or more of activated carbon, carbon nanotubes, porous carbon, graphene, and carbon fibers, as long as the carbon material can reversibly adsorb and desorb anions in the electrolyte, and the kind of the carbon material is not limited in the present invention.
The carbon material is, for example, one or more of granular activated carbon, powdered activated carbon, graphene, mesocarbon microbeads, three-dimensional ordered mesoporous carbon spheres, activated carbon fibers, activated carbon felt, activated carbon cloth, template skeleton carbon, carbide-derived carbon, carbon nanotubes, carbon aerogel, glassy carbon, nano charcoal or carbon foam.
The carbonaceous material is preferably granular activated carbon.
The calcium ion mixed super capacitor takes the positive electrode of the super capacitor as the positive electrode, the positive electrode active substance adopts a carbon material which can reversibly adsorb and desorb anions in electrolyte and has a large specific surface area, the material source is wide, the price is low, the preparation method is simple, and no chemical reaction occurs during working, thereby being beneficial to the calcium ion mixed super capacitor to obtain higher capacity density and longer service life.
It is understood that the positive electrode current collector of the calcium ion hybrid supercapacitor positive electrode is not particularly limited, and a positive electrode current collector commonly used in supercapacitors in the art may be used.
In a preferred embodiment, the positive electrode current collector includes, but is not limited to, one of aluminum, copper, iron, tin, zinc, nickel, titanium, or manganese, or an alloy containing at least any one thereof, such as stainless steel, or a composite containing at least any one of the metals, such as carbon-coated aluminum, carbon-coated copper, and the like.
[ electrolyte ]
The electrolyte of the calcium ion mixed super capacitor comprises calcium salt and a non-aqueous solvent.
The calcium salt is not limited, and a conventional calcium salt may be used.
The nonaqueous solvent refers to a solvent other than water, for example, an organic solvent or the like.
[ separator ]
It is to be understood that the separator is not particularly limited, and may be a common separator existing in the art.
In a preferred embodiment, the separator includes, but is not limited to, an insulating porous polymer film or an inorganic porous film.
In a preferred embodiment, the separator includes, but is not limited to, a porous polypropylene film, a porous polyethylene film, a porous composite polymer film, a non-woven fabric, a glass fiber paper, or a porous ceramic separator.
Preferably, the separator is a fiberglass paper.
The diaphragm of the hybrid super capacitor is positioned between the two electrodes and completely soaked in the electrolyte together with the electrodes, and plays a role in isolation in the repeated discharge process, thereby preventing electron conduction and preventing internal short circuit caused by contact between the two electrodes.
In a preferred embodiment, the calcium ion hybrid supercapacitor further comprises a housing or overwrap for packaging.
Any outer package may be appropriately selected without limitation as long as it is stable to the electrolyte and has sufficient water vapor barrier properties.
In addition, the form of the calcium ion hybrid supercapacitor provided by the present invention is not particularly limited, and may be any form commonly used in the art, such as a button type, a flat plate type, a cylindrical type, and the like.
The hybrid super capacitor comprises a positive electrode, a diaphragm, electrolyte, a negative electrode and other main components. The anode is a carbon-containing material with large specific surface area, the cathode is a metal foil (serving as a cathode active material and a current collector), the diaphragm is a common diaphragm of a battery or a capacitor, the electrolyte is a non-aqueous solution containing calcium ions, and the charge and discharge of the capacitor are realized by utilizing the adsorption/desorption action of the anode on anions and the alloy/dealloying reaction of the metal cathode and the calcium ions. The working mechanism is as follows: calcium ion (Ca) in electrolyte during charging2+) Carrying out alloying reaction with the negative electrode of the metal foil to generate an alloy phase; meanwhile, anions in the electrolyte are adsorbed by the anode material to finish the charging process; and (3) discharging: the negative pole generates dealloying reaction, calcium ions are removed from the negative pole and return to the electrolyte, and meanwhile, anions are desorbed from the positive pole and return to the electrolyte, so that the discharging process is completed.
The invention combines the advantages of high energy density of the calcium ion battery and high capacity density of the super capacitor, and can obtain the energy storage device with high energy density and capacity density. Calcium ions are used as active current carriers, the reaction main body of the generated electrochemical reaction is the calcium ions, and the calcium ions have two charges, so that the capacity of the super capacitor is improved. The integrated design of the negative electrode and the negative electrode current collector in the system is beneficial to increasing the active material proportion of the novel capacitor, simplifying the production process of the capacitor and reducing the manufacturing cost of devices. In addition, the metal negative electrode material capable of being alloyed with calcium ions is adopted, and the metal negative electrode material generally has higher specific capacity, so that the energy density of the novel capacitor is further increased.
According to the invention, through the difference of the whole system of the cathode, the anode and the electrolyte, the obtained calcium ion mixed super capacitor has high specific capacity, large energy density, excellent rate capability and good cycle stability, is a mixed super capacitor with high capacity and high energy density, and has wide application prospect.
In a preferred embodiment, the positive electrode material further includes a conductive agent and a binder.
In a preferred embodiment, the positive electrode material comprises 60-96 wt% of positive electrode material active substance, 1-30 wt% of conductive agent and 3-10 wt% of binder;
typical but non-limiting weight percentages of the positive electrode material active material, based on the positive electrode material, are, for example, 60%, 70%, 75%, 80%, 85%, 88%, 90%, 92%, 94%, or 96%.
Typical but non-limiting weight percentages of the conductive agent are, for example, 1%, 2%, 3%, 5%, 10%, 15%, 20%, 25%, or 30% based on the positive electrode material.
Typical but non-limiting weight percentages of the binder, based on the cathode material, are, for example, 3%, 5%, 6%, 7%, 8%, 9%, or 10%.
The positive electrode material obtained by adopting the positive electrode material active substance, the conductive agent and the binder in specific percentage has good comprehensive performance, and can well play the role of the positive electrode material in the calcium ion mixed super capacitor.
In a preferred embodiment, the conductive agent comprises one or at least two of conductive carbon black (acetylene black, Super P, Super S, 350G or ketjen black), conductive carbon spheres, conductive graphite, carbon nanotubes, conductive carbon fibers, graphene or reduced graphene oxide, preferably conductive carbon black.
The conductive agent is used for ensuring that the electrode has good charge and discharge performance, a certain amount of conductive substances are usually added during the manufacture of the pole piece, and the effect of collecting micro-current is achieved among active substances and between the active substances and a current collector, so that the movement rate of electrons accelerated by the contact resistance of the electrode is reduced, and meanwhile, the migration rate of calcium ions in the electrode material can be effectively improved, and the charge and discharge efficiency of the electrode is improved.
In a preferred embodiment, the binder comprises one or at least two of polyvinylidene fluoride, polytetrafluoroethylene, polyvinyl alcohol, carboxymethyl cellulose, SBR rubber or polyolefins, preferably polyvinylidene fluoride.
The binder has the main functions of binding and maintaining the active substance, enhancing the electronic contact between the electrode material active substance (carbon material) and the conductive agent as well as between the electrode material active substance and the current collector, better stabilizing the structure of the electrode, and playing a certain buffer role in the charge and discharge process of the super capacitor.
In a preferred embodiment, the concentration of the calcium salt in the electrolyte is 0.1-10mol/L, preferably 0.1-2mol/L, such as 0.1mol/L, 0.3mol/L, 0.6mol/L, 0.8mol/L, 1mol/L or 4 mol/L.
The ion concentration affects the ion transmission performance of the electrolyte in the system, the concentration of calcium salt in the electrolyte is too low, and Ca is added2+Too little, poor ion transmission performance, low conductivity, too high concentration of calcium salt in electrolyte, Ca2+Too much, the viscosity of the electrolyte and the degree of ionic association also increase with increasing calcium salt concentration, which in turn reduces conductivity. By adopting the specific calcium salt concentration, the obtained calcium ion mixed super capacitor can obtain higher energy density and specific capacitance.
In a preferred embodiment, the calcium salt comprises one or at least two of calcium hexafluorophosphate, calcium tetrafluoroborate, calcium chloride, calcium carbonate, calcium sulfate, calcium nitrate, calcium fluoride, calcium triflate, calcium bis (trifluoromethylsulfonyl) imide, calcium bis fluorosulfonimide or calcium perchlorate, preferably calcium hexafluorophosphate.
The type of electrolyte has an influence on the energy density and specific capacitance of the calcium ion hybrid supercapacitor, and better effects can be obtained by adopting a specific electrolyte.
In a preferred embodiment, the non-aqueous solvent is an organic solvent and/or an ionic liquid.
Preferably, the organic solvent includes one or at least two of ester, sulfone, ether, nitrile or olefin organic solvents.
Further preferably, the organic solvent includes Propylene Carbonate (PC), Ethylene Carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), Ethyl Methyl Carbonate (EMC), Methyl Formate (MF), Methyl Acetate (MA), N-Dimethylacetamide (DMA), fluoroethylene carbonate (FEC), Methyl Propionate (MP), Ethyl Propionate (EP), Ethyl Acetate (EA), γ -butyrolactone (GBL), Tetrahydrofuran (THF), 2-methyltetrahydrofuran (2MeTHF), 1, 3-Dioxolane (DOL), 4-methyl-1, 3-dioxolane (4MeDOL), Dimethoxymethane (DMM), 1, 2-Dimethoxypropane (DMP), triethylene glycol dimethyl ether (DG), dimethylsulfone (MSM), dimethyl ether (DME), Ethylene Sulfite (ES), ethylene carbonate (ES), and mixtures thereof, One or at least two of Propylene Sulfite (PS), dimethyl sulfite (DMS), diethyl sulfite (DES) or crown ether (12-crown-4), and preferably the organic solvent is a mixed solvent of ethylene carbonate, propylene carbonate, dimethyl carbonate and ethyl methyl carbonate.
Preferably, the ionic liquid comprises one or at least two of imidazole, piperidine, pyrrole, quaternary ammonium or amide ionic liquids.
Further preferably, the ionic liquid comprises 1-ethyl-3-methylimidazole-hexafluorophosphate, 1-ethyl-3-methylimidazole-tetrafluoroborate, 1-ethyl-3-methylimidazole-bistrifluoromethylsulfonyl imide salt, 1-propyl-3-methylimidazole-hexafluorophosphate, 1-propyl-3-methylimidazole-tetrafluoroborate, 1-propyl-3-methylimidazole-bistrifluoromethylsulfonyl imide salt, 1-butyl-1-methylimidazole-hexafluorophosphate, 1-butyl-1-methylimidazole-tetrafluoroborate, 1-butyl-1-methylimidazole-bistrifluoromethylsulfonyl imide salt, 1-ethyl-3-methylimidazole-tetrafluoroborate, 1-propyl-3-methylimidazole-bistrifluoromethylsulfonyl imide salt, 1-methyl-imidazole-tetrafluoroborate, 1-butyl-methyl-imidazole-bis-phosphonium chloride, 1-ethyl-methyl-bis (trifluoromethyl) phosphonium chloride, 1-ethyl-3-methyl imidazole-bis (trifluoromethyl) phosphonium chloride, 1-bis (trifluoromethyl) phosphonium chloride, or a salt, One or at least two of N-butyl-N-methylpyrrolidine-bis-trifluoromethylsulfonyl imide salt, 1-butyl-1-methylpyrrolidine-bis-trifluoromethylsulfonyl imide salt, N-methyl-N-propylpyrrolidine-bis-trifluoromethylsulfonyl imide salt, N-methyl, propylpiperidine-bis-trifluoromethylsulfonyl imide salt, or N-methyl, butylpiperidine-bis-trifluoromethylsulfonyl imide salt.
The ionic liquid has a higher voltage window, and can improve the electrode energy density of the hybrid super capacitor. The ionic liquid has almost no vapor pressure and is non-flammable, which allows the hybrid supercapacitor to maintain a high service life and high safety, and the hybrid supercapacitor can operate at high temperatures.
Different solvents have certain influence on the performance of the hybrid supercapacitor, and the specific solvent can be adopted to better dissociate calcium salt and better transmit Ca2+And the energy density and specific capacitance of the obtained hybrid super capacitor are higher.
In order to prevent the damage of the negative electrode caused by volume change during charging and discharging, keep the structure of the negative electrode stable, and improve the service life and the performance of the negative electrode so as to improve the cycle performance of the hybrid supercapacitor, the electrolyte also comprises an additive; the mass fraction of the additive in the electrolyte is 0.1-20%, preferably 2-5%;
typical but not limiting mass fractions of additives in the electrolyte are 0.1%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 12%, 15%, 18% or 20%.
The electrolyte is added with one or more additives to further improve one or more performances of the hybrid supercapacitor, and the additives are classified according to the action of the additives, and the additives comprise film forming additives (such as carbon dioxide, sulfur dioxide, lithium carbonate, sulfo-organic solvent, halogenated organic film forming additives and the like), overcharge protection additives (having redox couples, ortho-dimethoxy and para-dimethoxy substituted benzene, polymerization for increasing internal resistance and blocking charge, such as biphenyl, cyclohexylbenzene and the like), stabilizers, additives for improving high and low temperature performances, conductive additives or flame retardant additives (organic phosphide, organic fluoro compounds, halogenated alkyl phosphate) and the like.
The additives may be used singly or in combination of two or more kinds.
Preferably, the additive comprises one or at least two of ester, sulfone, ether, nitrile or olefin organic additives;
preferably, the additive comprises fluoroethylene carbonate, vinylene carbonate, ethylene carbonate, 1, 3-propane sultone, 1, 4-butane sultone, vinyl sulfate, propylene sulfate, ethylene sulfate, vinyl sulfite, propylene sulfite, dimethyl sulfite, diethyl sulfite, ethylene sulfite, methyl chloroformate, dimethyl sulfoxide, anisole, acetamide, diazabenzene, m-diazabenzene, crown ether 12-crown-4, crown ether 18-crown-6, 4-fluorophenylmethyl ether, fluoro chain ether, vinyl difluoromethyl carbonate, vinyl trifluoromethylcarbonate, vinyl chlorocarbonate, vinyl bromocarbonate, trifluoroethylphosphonic acid, bromobutyrolactone, fluoroacetoethane, phosphate, phosphite, phosphazene, ethanolamine, methyl acetate, and mixtures thereof, One or at least two of carbonized dimethylamine, cyclobutyl sulfone, 1, 3-dioxolane, acetonitrile, long-chain olefin, sodium carbonate, calcium carbonate, carbon dioxide, sulfur dioxide or lithium carbonate.
The life and performance of the hybrid supercapacitor can be further improved by adding certain amounts of specific additives to the electrolyte.
According to another aspect of the invention, a preparation method of the calcium ion hybrid supercapacitor is provided, wherein a negative electrode, an electrolyte, a diaphragm and a positive electrode are assembled to obtain the calcium ion hybrid supercapacitor.
It is to be understood that the assembly manner of the anode, the electrolyte, the separator, and the cathode is not particularly limited, and may be performed by a conventional assembly manner.
As a preferred embodiment, the preparation method of the calcium ion mixed super capacitor comprises the following steps:
a) preparing a negative electrode: treating the surface of the metal, alloy or metal compound with required size to serve as a negative electrode for later use;
b) preparing an electrolyte: dissolving calcium salt in a non-aqueous solvent, and fully mixing to obtain an electrolyte;
c) preparing a diaphragm: cutting a porous polymer film, an inorganic porous film or an organic/inorganic composite membrane into a required size to be used as a membrane;
d) preparing a positive electrode: adding the active substance of the positive electrode material, the conductive agent and the binder into a solvent according to a certain proportion, and fully mixing to form positive electrode material slurry; uniformly coating the positive electrode material slurry on the surface of a positive electrode current collector to form a positive electrode active material layer, drying, pressing and cutting into pieces to obtain a positive electrode with a required size;
assembling the negative electrode obtained in the step a), the electrolyte obtained in the step b), the diaphragm obtained in the step c) and the positive electrode obtained in the step d) to obtain the calcium ion mixed super capacitor.
When the positive electrode is prepared in the step d), weighing the positive electrode material active substance, the conductive agent and the binder according to a certain proportion, dissolving the positive electrode material active substance, the conductive agent and the binder in a proper solvent, fully grinding the positive electrode material active substance, the conductive agent and the binder into uniform slurry, preparing positive electrode material slurry, then coating the positive electrode material slurry on the surface of a positive electrode current collector, and obtaining the positive electrode with the required size after drying the positive electrode material slurry; or, when the positive electrode is prepared in the step d), weighing the positive electrode material active substance, the conductive agent and the binder according to a certain proportion, dissolving the positive electrode material active substance, the conductive agent and the binder in a proper solvent, fully grinding the mixture, rolling the mixture into a sheet, preparing a positive electrode sheet material, pressing the positive electrode sheet material on the surface of a positive electrode current collector under a certain pressure, and drying the positive electrode sheet material to obtain the positive electrode with the required size.
Preferably, typical solvents in step a) and step d) include water or N-methylpyrrolidone.
Preferably, the assembling specifically comprises: and tightly stacking or winding the prepared cathode, the diaphragm and the anode into a battery core in sequence under an inert gas or anhydrous oxygen-free environment, dripping electrolyte to completely soak the diaphragm, and then packaging into a shell to finish the assembly of the calcium ion mixed supercapacitor.
It should be noted that although the above steps describe the operations of the preparation method of the present invention in the order of a), b), c) and d), this does not require or imply that these operations must be performed in this particular order. The preparation of steps a), b), c) and d) can be carried out simultaneously or in any sequence.
The preparation method of the calcium ion hybrid supercapacitor and the calcium ion hybrid supercapacitor are based on the same inventive concept, and the calcium ion hybrid supercapacitor obtained by the preparation method of the calcium ion hybrid supercapacitor has all the effects of the calcium ion hybrid supercapacitor, and is not described herein again.
The invention is further illustrated by the following specific examples and comparative examples, but it should be understood that these examples are for purposes of illustration only and are not to be construed as limiting the invention in any way.
Example 1
A calcium ion mixed super capacitor comprises a negative electrode, a diaphragm, electrolyte and a positive electrode.
Preparing a capacitor anode: adding 0.8g of Activated Carbon (AC), 0.1g of conductive carbon black and 0.1g of polyvinylidene fluoride into 2mL of N-methylpyrrolidone, and fully grinding to obtain uniform slurry; then the slurry was uniformly coated on the surface of aluminum foil and vacuum dried at 80 ℃ for 12 hours. The dried electrode sheet was cut into a wafer having a diameter of 10mm, compacted by an oil press (10MPa for 10 seconds), and placed in a glove box as a battery positive electrode for standby.
Preparing a capacitor cathode: cutting tin foil with thickness of 100 μm into 12mm round pieces, cleaning with acetone and ethanol, drying, and placing in glove box as negative current collector.
Preparing an electrolyte: in a glove box, 1.32g of calcium hexafluorophosphate was weighed and added to 5mL of a mixed solution of ethylene carbonate, propylene carbonate, dimethyl carbonate and ethyl methyl carbonate (volume ratio v/v/v ═ 2:2:3:3), and the mixture was stirred until the calcium hexafluorophosphate was completely dissolved, and the mixture was used as an electrolyte solution.
Preparing a diaphragm: cutting the glass fiber paper into round pieces with the diameter of 16mm, drying in vacuum at 80 ℃ for 12h, and placing in a glove box to be used as a diaphragm for standby.
Assembling the capacitor: and (3) in a glove box in an argon atmosphere, tightly stacking the prepared positive electrode, the diaphragm and the negative electrode in sequence, dripping electrolyte to completely soak the diaphragm, and packaging the stacked part into a shell to finish the assembly of the calcium ion mixed super capacitor.
Examples 2 to 12
The calcium ion hybrid supercapacitor of examples 2 to 12 and example 1 were prepared by the same procedure and using the same materials except that the metal foil used in the preparation of the negative electrode was different, and the energy storage performance of the hybrid supercapacitor of examples 2 to 12 was tested by a conventional test method and compared with that of example 1, and the energy storage performance of the negative electrode materials and capacitors used in examples 2 to 12 is shown in table 1.
TABLE 1 TABLE OF PERFORMANCE PARAMETERS OF HYBRID SUPERCAPACITORS OF EXAMPLES 2-12
Examples 2 to 12 compared with example 1, the electrochemical performance of the obtained calcium ion hybrid supercapacitor was different due to the different metal materials used for the negative electrode, wherein the calcium ion hybrid supercapacitor obtained by using tin foil as the negative electrode was the best in specific capacitance and energy density performance.
Examples 13 to 24
The calcium ion hybrid supercapacitor of examples 13 to 24 and example 1 were fabricated using the same materials and the same materials except that the materials used for the positive electrode active material were different, and the energy storage performance of the hybrid supercapacitor of examples 13 to 24 was tested and compared with that of example 1, and the energy storage performance of the positive electrode active material and the capacitor used in examples 13 to 24 are shown in table 2.
TABLE 2 TABLE OF PERFORMANCE PARAMETERS OF HYBRID SUPERCAPACITORS OF EXAMPLES 13-24
Examples 13 to 24 have different electrochemical properties of the calcium ion hybrid supercapacitor obtained by using the activated carbon as the positive electrode active material compared to example 1, wherein the specific capacitance and energy density of the calcium ion hybrid supercapacitor obtained by using the activated carbon as the positive electrode active material in example 1 are higher than those of the calcium ion hybrid supercapacitor obtained by using other carbon materials as the positive electrode active material, and the effect is better.
Examples 25 to 28
The calcium ion hybrid supercapacitor of examples 25-28 were prepared according to the same procedure and using the same materials as those used in the calcium ion hybrid supercapacitor of example 1, except that the materials used in the separator were different, and the energy storage performance of the hybrid supercapacitor of examples 25-28 was tested and compared with that of example 1, and the energy storage performance of the separator and capacitor used in examples 25-28 is shown in table 3.
TABLE 3 TABLE of Performance parameters for hybrid ultracapacitors of examples 25-28
| Example numbering | Separator material | Energy Density (Wh/kg) | Specific capacitance (F/g) |
| 25 | Porous ceramic diaphragm | 290 | 146 |
| 26 | Porous polypropylene film | 293 | 146 |
| 27 | Porous polyethylene film | 292 | 146 |
| 28 | Porous composite polymer film | 294 | 146 |
| 1 | Glass fiber paper | 295 | 146 |
Examples 25-28 the supercapacitors used different separators compared to example 1, and the resulting calcium ion hybrid supercapacitors differed in electrochemical performance but not much, with the higher energy density of the calcium ion hybrid supercapacitors obtained using the fiberglass paper separator of example 1.
Examples 29 to 42
The energy storage performance of the hybrid supercapacitors of examples 29-42 was tested and compared to that of example 1, except that the calcium ion hybrid supercapacitor of examples 29-42 was made using the same materials and procedures except that the electrolyte solvent materials and their formulation were varied as in example 1, and the solvents used and the capacitor energy storage performance of examples 29-42 are shown in table 4.
TABLE 4 TABLE of Performance parameters for the hybrid ultracapacitors of examples 29-42
In examples 29 to 42, the electrolyte used different solvents compared with example 1, and the electrochemical performance of the obtained calcium ion hybrid supercapacitor differed particularly in specific capacitance and energy density, and it can be seen that the electrolyte solvent has an important influence on the specific capacitance and energy density of the hybrid supercapacitor. Wherein the energy density and specific capacitance of the calcium ion hybrid supercapacitor obtained by using the solvent (the mixed solvent of ethylene carbonate, propylene carbonate, dimethyl carbonate and ethyl methyl carbonate, wherein the volume ratio of ethylene carbonate to propylene carbonate to dimethyl carbonate to ethyl methyl carbonate is 2:2:3:3) in example 1 are higher.
Examples 43 to 51
The calcium ion hybrid supercapacitor of examples 43-51 and example 1 were prepared using the same materials and the same procedures except that the materials used for the electrolyte were different, and the energy storage performance of the hybrid supercapacitor of examples 43-51 was tested and compared with that of example 1, and the electrolyte materials used in examples 43-51 and the energy storage performance of the capacitor are shown in table 5.
TABLE 5 Table of Performance parameters for hybrid supercapacitors of examples 43-51
Examples 43-51 compared with example 1, the electrolyte used Ca salt, and the obtained calcium ion mixed super capacitor has different energy density and specific capacitance, wherein the electrolyte used Ca (PF)6)2The obtained calcium ion mixed super capacitor has better performance, higher energy density and specific capacitance.
Examples 52 to 56
The calcium ion hybrid supercapacitor of examples 52-56 and example 1 were prepared using the same materials and procedures except that the electrolyte concentration in the electrolyte was varied, and the energy storage performance of the hybrid supercapacitor of examples 52-56 was tested and compared with that of example 1, and the electrolyte concentration and capacitor energy storage performance used in examples 52-56 are shown in table 6.
TABLE 6 TABLE OF PERFORMANCE PARAMETERS FOR HYBRID SUPERCAPACITORS OF EXAMPLES 52-56
| Example numbering | Electrolyte concentration (mol/L) | Energy Density (Wh/kg) | Specific capacitance (F/g) |
| 52 | 0.1M | 140 | 85 |
| 53 | 0.3M | 190 | 98 |
| 54 | 0.6M | 220 | 112 |
| 55 | 1M | 278 | 137 |
| 56 | 4M | 272 | 135 |
| 1 | 0.8M | 295 | 146 |
Examples 52-56 compared to example 1, the capacitors used different electrolyte concentrations, which had a significant effect on the specific capacitance and energy density of the hybrid supercapacitor. Among them, the calcium ion hybrid supercapacitor obtained by using the electrolyte containing 0.8M of electrolyte in example 1 has higher capacity and higher energy density.
Examples 57 to 64
The calcium ion hybrid supercapacitor of examples 57-64 and example 1 were prepared using the same materials and the same additives except that the additives and the amounts thereof in the electrolyte were different, and the energy storage performance of the hybrid supercapacitor of examples 57-64 was tested and compared with the performance of example 1, and the additives and amounts of the electrolyte and the energy storage performance of the capacitor used in examples 57-64 are shown in table 7.
TABLE 7 TABLE of Performance parameters for hybrid supercapacitors of examples 57-64
Examples 57-64 the types of additives used in the supercapacitors differed from example 1, and the resulting calcium ion hybrid supercapacitors differed in performance, with the capacitors of example 1 using no additives achieving higher energy density and specific capacitance.
Examples 65 to 71
The calcium ion hybrid supercapacitor of examples 65 to 71 and example 1 were prepared using the same materials and procedures except that the conductive agent and binder materials contained in the prepared positive electrode were different, and the energy storage performance of the hybrid supercapacitor of examples 65 to 71 was tested and compared with that of example 1, and the conductive agent and binder materials contained in the positive electrode, and the energy storage performance of the capacitor of examples 65 to 71 are shown in table 8.
TABLE 8 TABLE of Performance parameters for the hybrid supercapacitors of examples 65-71
Examples 65-71 compared to example 1, the types and contents of the conductive agent and the binder used in the positive electrode material were different, and the electrochemical performance of the obtained calcium ion hybrid supercapacitor was slightly different, wherein the energy storage performance of the calcium ion hybrid supercapacitor obtained by using 10% of conductive carbon black conductive agent and 10% of polyvinylidene fluoride binder was the best.
Therefore, in a calcium ion system, different types, concentrations, contents and the like of the negative electrode material, the positive electrode active material, the conductive agent, the binder, the electrolyte solute, the solvent can influence the energy storage performance of the capacitor, and in example 1, the calcium ion hybrid supercapacitor obtained by adopting the specific negative electrode material, the positive electrode active material, the conductive agent, the binder and the electrolyte can obtain the optimal energy storage performance.
Comparative example 1
A lithium ion hybrid supercapacitor comprises a negative electrode, a diaphragm, electrolyte and a positive electrode.
Preparing a negative electrode: mixing graphite, conductive carbon black and polyvinylidene fluoride (PVDF) according to a mass ratio of 80:10:10, mixing the mixture into slurry by using N-methyl pyrrolidone (NMP), then coating the slurry on the surface of an aluminum foil, drying the aluminum foil in vacuum, and cutting the dried electrode slice into a circular slice with the diameter of 12mm to be used as a negative electrode for later use.
Preparing a diaphragm: the glass fiber diaphragm is cut into a circular piece with the diameter of 16mm, and the circular piece is dried to be used as the diaphragm for standby.
Preparing an electrolyte: 3g of lithium hexafluorophosphate was weighed into 5mL of ethylene carbonate: stirring the mixture in methyl ethyl carbonate (v/v is 1:1) until lithium hexafluorophosphate is completely dissolved, adding vinylene carbonate with the mass fraction of 5% as an additive, and fully and uniformly stirring the mixture to be used as an electrolyte for later use.
Preparing a positive electrode: adding 0.8g of Activated Carbon (AC), 0.1g of conductive carbon black and 0.1g of polyvinylidene fluoride into 2mL of nitrogen methyl pyrrolidone solvent, and fully grinding to obtain uniform slurry; the slurry was then uniformly coated on the aluminum foil surface and vacuum dried. The dried electrode sheet was cut into a circular piece having a diameter of 12mm, and the circular piece was used as a positive electrode.
Assembling: and assembling the prepared cathode, the diaphragm, the electrolyte and the anode into a hybrid supercapacitor in a glove box protected by inert gas.
After testing, the energy density of the lithium ion hybrid super capacitor is 126Wh/kg, and the specific capacitance is 70F/g.
Comparative example 2
A sodium ion hybrid supercapacitor comprises a negative electrode, a diaphragm, electrolyte and a positive electrode. Wherein the negative electrode includes a negative active material and a current collector, the negative active material being amorphous hard carbon.
Preparing a negative electrode: mixing hard carbon, conductive carbon black and polyvinylidene fluoride (PVDF) according to the mass ratio of 80:10:10, mixing the mixture into slurry by using N-methyl pyrrolidone (NMP), and then coating the surface of an aluminum foil (coating surface capacity: 12 Ah/m)2) And vacuum drying, and cutting the dried electrode plate into a circular piece with the diameter of 12mm as a negative electrode for standby.
Preparing a diaphragm: the glass fiber diaphragm is cut into a circular piece with the diameter of 16mm, and the circular piece is dried to be used as the diaphragm for standby.
Preparing an electrolyte: 0.504g of sodium hexafluorophosphate (NaPF) was weighed out6) To 3mL of Ethylene Carbonate (EC), dimethyl carbonate (DMC) and methyl ethyl carbonate (EMC) (volume ratio)1:1:1) in the solvent, stirring until sodium hexafluorophosphate is completely dissolved, and taking the solution as electrolyte for standby.
Preparing a positive electrode: adding 0.16g of carbon nanobelt, 0.02g of acetylene black and 0.02g of polyvinylidene fluoride into 2mL of N-methylpyrrolidone solution, and fully grinding to obtain uniform slurry; the slurry was then uniformly coated on the aluminum foil surface and vacuum dried. The dried electrode sheet was cut into a wafer having a diameter of 10mm, and the wafer was used as a positive electrode.
Assembling: and assembling the prepared cathode, the diaphragm, the electrolyte and the anode into a hybrid supercapacitor in a glove box protected by inert gas.
After the test, the energy density of the sodium ion hybrid super capacitor is 180Wh/kg, and the specific capacitance is 120F/g.
Comparative example 3
A sodium ion hybrid supercapacitor comprises a negative electrode, a diaphragm, electrolyte and a positive electrode.
Preparing a negative electrode: taking a tin foil with the thickness of 0.2mm, cutting the tin foil into a wafer with the diameter of 12mm, washing the tin foil with ethanol, and drying the tin foil to be used as a negative electrode for later use.
Preparing a diaphragm: the glass fiber diaphragm is cut into a circular piece with the diameter of 16mm, and the circular piece is dried to be used as the diaphragm for standby.
Preparing an electrolyte: 0.504g of sodium hexafluorophosphate (NaPF6) was weighed into 3mL of a solvent of Ethylene Carbonate (EC), dimethyl carbonate (DMC) and methyl ethyl carbonate (EMC) (volume ratio 1:1:1), and stirred until the sodium hexafluorophosphate was completely dissolved, to be used as an electrolyte.
Preparing a positive electrode: adding 0.16g of carbon nanobelt, 0.02g of acetylene black and 0.02g of polyvinylidene fluoride into 2mL of N-methylpyrrolidone solution, and fully grinding to obtain uniform slurry; the slurry was then uniformly coated on the aluminum foil surface and vacuum dried. The dried electrode sheet was cut into a wafer having a diameter of 10mm, and the wafer was used as a positive electrode.
Assembling: and assembling the prepared cathode, the diaphragm, the electrolyte and the anode into a hybrid supercapacitor in a glove box protected by inert gas.
After the test, the energy density of the sodium ion hybrid super capacitor is 228Wh/kg, and the specific capacitance is 135F/g.
The calcium ion hybrid supercapacitor of the invention has long service life, high specific capacitance and high energy density, and compared with example 1, comparative example 1 is a conventional lithium ion hybrid supercapacitor, which has lower energy density, short service life, limited lithium storage, high cost and toxicity, and limits the application of the lithium ion hybrid supercapacitor. Compared with the embodiment 1, the comparative example 2 is a sodium ion hybrid supercapacitor, the cathode active material is amorphous hard carbon, the energy density and the specific capacitance of the device are lower, the comparative example 3 is also the sodium ion hybrid supercapacitor, but the cathode material and the current collector adopt tin foil, the energy density and the specific capacitance of the obtained capacitor are not as good as those of a calcium ion hybrid supercapacitor, so that the capacitor performance difference under different systems is larger, calcium ions are divalent ions under a calcium ion system, higher capacity can be provided, the reduction potential of calcium is lower, the voltage is higher than that of magnesium, the storage capacity of calcium is richer, and the capacitor with better energy storage performance can be obtained by matching with the use of the anode and the cathode under the calcium ion system.
FIG. 2 is a graph showing the relationship between the time and the charging and discharging voltage at circles 8, 9 and 10 of the calcium ion hybrid supercapacitor according to the present invention. It is charged and discharged with constant current, and the current density is 0.1A/g. As can be seen from fig. 2, the calcium ion hybrid supercapacitor of the present invention has a complete charge-discharge curve, a higher discharge voltage and a high coulombic efficiency.
While particular embodiments of the present invention have been illustrated and described, it would be obvious that various other changes and modifications can be made without departing from the spirit and scope of the invention. It is therefore intended to cover in the appended claims all such changes and modifications that are within the scope of this invention.
Claims (4)
1. A calcium ion hybrid supercapacitor is characterized by comprising a negative electrode, a positive electrode, a diaphragm between the positive electrode and the negative electrode and electrolyte;
the negative electrode is tin foil;
the positive electrode comprises a positive current collector and a positive material; the positive electrode material comprises a positive electrode material active substance, a conductive agent and an adhesive, wherein the positive electrode material active substance is granular activated carbon, the conductive agent is conductive carbon black, and the adhesive is polyvinylidene fluoride; wherein the mass ratio of the activated carbon to the conductive carbon black to the polyvinylidene fluoride is 8:1: 1;
the electrolyte comprises a calcium salt and a non-aqueous solvent; the calcium salt is calcium hexafluorophosphate, and the concentration is 0.8 mol/L; the non-aqueous solvent is a mixed solvent of ethylene carbonate, propylene carbonate, dimethyl carbonate and ethyl methyl carbonate, wherein the volume ratio of the ethylene carbonate: propylene carbonate: dimethyl carbonate: ethyl methyl carbonate 2:2:3: 3;
the diaphragm is glass fiber paper.
2. The calcium ion hybrid supercapacitor according to claim 1, further comprising an additive in the electrolyte;
the mass fraction of the additive in the electrolyte is 0.1-20%;
the additive comprises one or at least two of ester, sulfone, ether, nitrile or olefin organic additives.
3. The method for preparing the calcium ion hybrid supercapacitor according to any one of claims 1 to 2, wherein the negative electrode, the electrolyte, the separator and the positive electrode are assembled to obtain the calcium ion hybrid supercapacitor.
4. The method for preparing a calcium ion hybrid supercapacitor according to claim 3, comprising the steps of:
a) preparing a negative electrode: treating the surface of the metal, alloy or metal compound with required size to serve as a negative electrode for later use;
b) preparing an electrolyte: dissolving calcium salt in a non-aqueous solvent, and fully mixing to obtain an electrolyte;
c) preparing a diaphragm: cutting a porous polymer film, an inorganic porous film or an organic/inorganic composite membrane into a required size to be used as a membrane;
d) preparing a positive electrode: adding the active substance of the positive electrode material, the conductive agent and the binder into a solvent according to a certain proportion, and fully mixing to form positive electrode material slurry; uniformly coating the positive electrode material slurry on the surface of a positive electrode current collector to form a positive electrode active material layer, drying, pressing and cutting into pieces to obtain a positive electrode with a required size;
assembling the negative electrode obtained in the step a), the electrolyte obtained in the step b), the diaphragm obtained in the step c) and the positive electrode obtained in the step d) to obtain the calcium ion mixed super capacitor.
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