It is a kind of can low temperature charging lithium-ion capacitor and preparation method thereofTechnical field
The invention belongs to electrochemical energy storing device technical fields, and in particular to it is a kind of can low temperature charging lithium-ion capacitorAnd preparation method thereof.
Background technique
Recently for over ten years, the enhancing with using energy source to small-sized discrete and removableization direction development trend, it is variousEnergy storage device (including lead-acid battery, nickel-metal hydride battery, lithium ion battery etc.) obtains great development.And as electric car is answeredWith the rapid expansion in market, other than the energy density to energy storage device there are certain requirements, the requirement to power density is increasinglyHeight, some have been over the standard designed capacity of current secondary cell, and traditional electrostatic condenser is also because energy density is too lowIt cannot meet the requirements, lithium-ion capacitor is considered as the effective solution for meeting people's energy requirement in industry and lifeOne of.
Lithium-ion capacitor uses the principle of double layer capacitor in design, constructively uses lithium ion batteryNegative electrode material and the positive electrode of double layer capacitor combine, if cathode is using carbonaceous material, it is necessary to negativeExtremely addition lithium ion, the lithium-ion capacitor energy density of this system perhaps can improve in advance, but since its carbon material used as anode is embeddingLithium current potential is less than or equal to 0.2V vs Li close to the deposition potential of lithium metal+, cause this system lithium-ion capacitor can not beLow temperature environment less than zero degrees celsius charges, and otherwise may cause cathode analysis lithium short circuit.
Using carbon, such as graphite, hard carbon and soft carbon etc., as cathode, the insertion of lithium and abjection cathode energy under low temperature environmentPower decline, the especially decline of insertion ability, so charge ratio electric discharge is more difficult under low temperature, this influences whether filling for lithium-ion capacitorDischarge current.When charging current is excessive, lithium ion insertion cathode rate decline causes it to be deposited on battery in the form of atomic stateSurface, this may cause capacitor and security risk occurs.
In the prior art, G.G..Amatucci et al. reports one kind with active carbon as anode, lithium titanate Li4Ti5O12ForThe hybrid super capacitor of cathode.Cathode Li4Ti5O12Intercalation potential is in 1.5V (vs Li+) left and right, cause its operating voltage section1.7~2.8V, electrolyte are the LiPF of 1.5mol/L6Acetonitrile solution, the capacity retention ratio under 10C charge-discharge magnification reach90%, the capacitance loss after recycling for 5000 weeks is 10~15%.
Although low temperature charging theoretically may be implemented in the above-mentioned lithium-ion capacitor using carbonic acid cathode of lithium, merelyFor lithium carbonate/charcoal system lithium-ion capacitor under the use state of low temperature environment, positive effective use section is narrow, utilizesRate is lower than 50%, limits Li4Ti5O12The raising of/AC system lithium-ion capacitor capacity and energy density, to limit itApplication at low ambient temperatures.
Summary of the invention
The object of the present invention is to provide it is a kind of can low temperature charging lithium-ion capacitor, while realizing low temperature charging,With wider operating voltage section and higher energy density.
A second object of the present invention is to provide it is a kind of it is above-mentioned can low temperature charging lithium-ion capacitor preparation method.
In order to achieve the goal above, the technical scheme adopted by the invention is that:
It is a kind of can low temperature charging lithium-ion capacitor, including positive plate, negative electrode tab, diaphragm and electrolyte；
The positive plate includes plus plate current-collecting body and the positive electrode active material layer that plus plate current-collecting body one or both sides are arranged in,Positive active material in positive electrode active material layer is active carbon, charcoal-aero gel, activated carbon fibre, any one in grapheneOr combination；The positive electrode active material layer surface is additionally provided with metallic lithium layer；
The negative electrode tab includes negative current collector and the negative electrode active material layer that negative current collector one or both sides are arranged in,Negative electrode active material in negative electrode active material layer is lithium titanate.
The positive electrode active material layer includes positive active material, conductive agent and binder, positive active material, conductive agentMass ratio with binder is 85:(7~9): (6~8)；The negative electrode active material layer includes negative electrode active material, conductive agentAnd binder, the mass ratio of negative electrode active material, conductive agent and binder are (92~93): (3.5~4.5): (3~3.5).
The conductive agent is acetylene black, Super P, any one or combination in carbon nanotube；The binder is poly-Tetrafluoroethene (PTFE), Kynoar (PVDF), butadiene-styrene rubber, any one or combination in carboxymethyl cellulose.AnodeIn active material layer and negative electrode active material layer, conductive agent used be it is independent, can be the same or different；It is usedBonding agent be also it is independent, can be the same or different.
The surface density of the positive electrode active material layer is 58~60g/cm2, compacted density is 0.6~0.65g/cm3。
The metallic lithium layer is to be compounded in what positive electrode active material layer surface was formed in such a way that lithium metal is by roll-in；The lithium metal is inertia lithium powder, lithium net, any one in lithium band.
The quality of the metallic lithium layer is the 0.3%~1% of positive active material quality.
The plus plate current-collecting body is aluminium foil；The negative current collector is copper foil.
The diaphragm is polyethylene porous membrane or polypropylene porous film；Diaphragm is arranged between positive plate and negative electrode tab.
The electrolyte includes organic solvent and the lithium salts for being dissolved in organic solvent；The lithium salts is lithium hexafluoro phosphate.InstituteStating the concentration of lithium hexafluoro phosphate in the electrolytic solution is 1.0~1.2mol/L.
Organic solvent used in electrolyte is ethylene carbonate, propene carbonate and dimethyl carbonate or diethyl carbonateMixture.Preferably, the volume ratio of ethylene carbonate, propene carbonate and dimethyl carbonate or diethyl carbonate be (3~3.5): (0.5~1): 4.
It is a kind of it is above-mentioned can low temperature charging lithium-ion capacitor preparation method, including the following steps:
1) take positive active material, conductive agent and binder that anode sizing agent is made, side coated in plus plate current-collecting body orTwo sides, drying, roll-in form positive electrode active material layer；Lithium metal is laid on positive electrode active material layer surface, roll-in forms lithiumMetal layer obtains positive plate；
Take negative electrode active material, conductive agent and binder that negative electrode slurry is made, the side coated in negative current collector or twoSide, drying, roll-in form negative electrode active material layer, obtain negative electrode tab；
2) by positive plate obtained by step 1), negative electrode tab and diaphragm, electrolyte assembling to get the lithium-ion capacitor.
In step 1), the positive plate without lithium metal layer with a thickness of 150~250 μm.
In step 1), when forming lithium metal layer, the pressure of the roll-in is 50~150kg/cm2。
In step 1), the temperature of the drying is 100~180 DEG C.
In step 1), during preparing negative electrode tab, the coating layer thickness after drying is 220~260 μm, negative after roll-inPole piece with a thickness of 100~120 μm.
It is of the invention can the lithium-ion capacitor of low temperature charging use lithium titanate for negative electrode active material.Lithium titanate lithium fromVolume change is small during son insertion, abjection, almost nil, and has very stable discharge platform, is higher than absolutely mostlyThe reduction potential of number electrolyte solvent, does not form SEI film, and coulombic efficiency is high；Lithium titanate anode charges at -30 DEG CThe Li dendrite for leading to short circuit or deteriorating cathode occurs, this is that graphite cathode can not be accomplished, can be fast under extensive environmentSpeed is charged and discharged.
The electrochemical window that positive carbon activity material is capable of steady operation in the organic electrolyte containing lithium ion is about1.3~4.5V (vs Li+), to system carry out it is pre- mend lithium when, Carbon Materials to the take-off potential of lithium in 3V or so, with lithium current potentialThe voltage difference that the lithium titanate anode of 1.5V or so is combined is in 1.5V or so, with Li4Ti5O12/ AC (active carbon) system lithiumFor ionistor, 1.5V is exactly theoretic minimum operating voltage, guarantees the cycle life of product on Practical ProjectEtc. performances minimum voltage is set to 1.7V.Only about 3~4.5V, utilization rate are lower than in anode effective use section under this state50%, limit Li4Ti5O12The raising of/AC system lithium-ion capacitor capacity and energy density.
It is of the invention can the negative electrode active material of lithium-ion capacitor of low temperature charging be active carbon, charcoal-aero gel, activityAny one in Carbon fibe, graphene or combination.The supplement that lithium source is carried out to lithium titanate/charcoal system, since lithium titanate hasVery stable discharge platform, it is difficult to embedding lithium degree be judged by potential change, so the benefit lithium of monitoring system is imitated for convenienceFruit carries out pre- embedding lithium to positive carbon material, and positive Electrostatic Absorption amount of lithium ions can be intuitively reflected in voltage change, and gram volume is embeddingThe quality of lithium amount and positive plate active material layer is 0.3%-1% than range.For example, with surface density 60g/m2, 84F/g activityFor charcoal pole piece, if mending lithium amount is designed as 0.4%, Li after fluid injection4Ti5O12The voltage of/AC system lithium-ion capacitor is answeredIt should be in 0.5~0.6V.
It is of the invention can low temperature charging lithium-ion capacitor, positive active material is with Electrostatic Absorption ion characteristicActive material (active carbon, charcoal-aero gel, activated carbon fibre, any one or combination in graphene), negative electrode active material isCan it is embedding desorption lithium ion lithium titanate, by positive electrode active material layer surface be arranged metallic lithium layer carry out anode mend lithium, open upWide lithium titanate/charcoal system lithium-ion capacitor operating voltage section, also improves energy density while realizing low temperature charging.Li of the invention4Ti5O12/ AC system lithium-ion capacitor 0.5~2.8V of operating voltage, -40 DEG C of charging capacity conservation rates of low temperature70% or more, there is preferable multiplying power discharging capacity retention ratio, circulation volume conservation rate and low temperature charging conservation rate, have preferableChemical property；While realizing low temperature charging, there is wider operating voltage section and higher energy density.
It is of the invention can low temperature charging lithium-ion capacitor preparation method, the preparation of positive plate is (lazy using lithium metalProperty lithium powder, lithium net or lithium band) be compounded in positive electrode active material layer surface by way of roll-in and form metallic lithium layer；The preparation sideMethod simple process, it is easy to operate, it is easy to automation control, is suitble to large-scale industrial production.When preparing lithium metal layer, roll-inPressure control in 50~150kg/cm2, the contact area of lithium metal and positive plate is increased, lithium metal ionization speed is acceleratedDegree, improves production efficiency.
Specific embodiment
The present invention is further illustrated With reference to embodiment.
Embodiment 1
The present embodiment can low temperature charging lithium-ion capacitor, including positive plate, negative electrode tab, diaphragm and electrolyte；
The positive plate includes plus plate current-collecting body aluminium foil and the positive electrode active material layer that plus plate current-collecting body two sides are arranged in, instituteStating positive electrode active material layer includes positive electrode active material activated carbon, conductive agent acetylene black, polyfluortetraethylene of binding element (PTFE), is livedProperty charcoal, acetylene black, polytetrafluoroethylene (PTFE) mass ratio be 85:7:8, the surface density of the positive electrode active material layer is 58g/cm2, pressureReal density is 0.6g/cm3；
The positive electrode active material layer surface is equipped with metallic lithium layer, and the metallic lithium layer is to pass through roller using inertia lithium powderThe mode of pressure is compounded in the formation of positive electrode active material layer surface, and the quality of metallic lithium layer is positive active material quality0.7%；
The negative electrode tab includes negative current collector copper foil and the negative electrode active material layer that negative current collector two sides are arranged in, instituteStating negative electrode active material layer includes negative electrode active material lithium titanate, conductive agent Super P, binder Kynoar (PVDF),Lithium titanate, Super P, Kynoar mass ratio be 93:4:3.
The present embodiment can low temperature charging lithium-ion capacitor preparation method, including the following steps:
1) it takes positive electrode active material activated carbon, conductive agent acetylene black and polyfluortetraethylene of binding element uniformly to mix, is made justPole slurry, the both side surface using coater in plus plate current-collecting body aluminium foil, 120 DEG C of drying, roll-in form positive electrode active materialMatter layer (overall thickness of collector and positive electrode active material layer is 200 μm), slitting；Inertia lithium powder is uniformly laid on positive-activeSubstance layer surface, in 150kg/cm2Pressure lower roll swaging at lithium metal layer, (roll-in makes lithium powder surface inertness damage layer exposedLithium metal), obtain positive plate；
It takes negative electrode active material lithium titanate, Super P, binder Kynoar uniformly to mix, negative electrode slurry is made, adoptsWith coater in the both side surface of negative current collector copper foil, after 120 DEG C of drying, coating layer thickness is 260 μm, and roll-in forms negativePole active material layer obtains the negative electrode tab with a thickness of 120 μm, and trimming, cut-parts, slitting is wound, spare；
2) diaphragm and electrolyte are taken, diaphragm is microporous polypropylene membrane；Lithium salts used in electrolyte is lithium hexafluoro phosphate, hexafluoro phosphorusThe concentration of sour lithium in the electrolytic solution is 1.0mol/L, and organic solvent used is ethylene carbonate, propene carbonate, dimethyl carbonateThe mixed solvent mixed according to volume ratio 3:1:4；
Takeup type battery core is made in gained positive plate, diaphragm, negative electrode tab, enters shell, injects electrolyte, standing (records quiet for 24 hoursPostpone voltage value, after standing voltage value be 0.5~0.6V), 0.5V constant-current charge to 2.8V is melted into, exhaust molding to getThe lithium-ion capacitor.
Embodiment 2
The present embodiment can low temperature charging lithium-ion capacitor, including positive plate, negative electrode tab, diaphragm and electrolyte；
The positive plate includes plus plate current-collecting body aluminium foil and the positive electrode active material layer that plus plate current-collecting body two sides are arranged in, instituteStating positive electrode active material layer includes positive electrode active material activated carbon, conductive agent Super P, polyfluortetraethylene of binding element (PTFE),Active carbon, Super P, polytetrafluoroethylene (PTFE) mass ratio be 85:8:7, the surface density of the positive electrode active material layer is 60g/cm2, compacted density 0.63g/cm3；
The positive electrode active material layer surface is equipped with metallic lithium layer, and the metallic lithium layer crosses roll-in using lithium NetcomMode is compounded in the formation of positive electrode active material layer surface, and the quality of metallic lithium layer is the 0.5% of positive active material quality；
The negative electrode tab includes negative current collector copper foil and the negative electrode active material layer that negative current collector two sides are arranged in, instituteStating negative electrode active material layer includes negative electrode active material lithium titanate, conductive agent carbon nanotube, binder Kynoar (PVDF),Lithium titanate, carbon nanotube, Kynoar mass ratio be 93.5:3.5:3.
The present embodiment can low temperature charging lithium-ion capacitor preparation method, including the following steps:
1) it takes positive electrode active material activated carbon, conductive agent Super P and polyfluortetraethylene of binding element uniformly to mix, is made justPole slurry, the both side surface using coater in plus plate current-collecting body aluminium foil, 120 DEG C of drying, roll-in form positive electrode active materialMatter layer (overall thickness of collector and positive electrode active material layer is 150 μm), slitting；Lithium net is stacked and is laid on positive active materialLayer surface (area of lithium net is identical as positive electrode active material layer area), in 100kg/cm2Pressure lower roll swaging at lithium metalLayer, obtains positive plate；
It takes negative electrode active material lithium titanate, carbon nanotube, binder Kynoar uniformly to mix, negative electrode slurry is made,Using coater in the both side surface of negative current collector copper foil, after 120 DEG C of drying, coating layer thickness is 260 μm, and roll-in is formedNegative electrode active material layer obtains the negative electrode tab with a thickness of 120 μm, and trimming, cut-parts, slitting is wound, spare；
2) diaphragm and electrolyte are taken, diaphragm is polyethene microporous membrane；Lithium salts used in electrolyte is lithium hexafluoro phosphate, hexafluoro phosphorusThe concentration of sour lithium in the electrolytic solution is 1.0mol/L, and organic solvent used is ethylene carbonate, propene carbonate, diethyl carbonateThe mixed solvent mixed according to volume ratio 3.5:0.5:4；
Takeup type battery core is made in gained positive plate, diaphragm, negative electrode tab, enters shell, injects electrolyte, standing (records quiet for 24 hoursPostpone voltage value, after standing voltage value be 0.5~0.6V), 0.5V constant-current charge to 2.8V is melted into, exhaust molding to getThe lithium-ion capacitor.
Embodiment 3
The present embodiment can low temperature charging lithium-ion capacitor, including positive plate, negative electrode tab, diaphragm and electrolyte；
The positive plate includes plus plate current-collecting body aluminium foil and the positive electrode active material layer that plus plate current-collecting body two sides are arranged in, instituteStating positive electrode active material layer includes positive electrode active material activated carbon, conductive agent Super P, binder butadiene-styrene rubber (SBR) and carboxylicMethylcellulose (CMC), active carbon, Super P, butadiene-styrene rubber, carboxymethyl cellulose mass ratio be 85:9:4:2, it is described justThe surface density of pole active material layer is 60g/cm2, compacted density 0.63g/cm3；
The positive electrode active material layer surface is equipped with metallic lithium layer, and the metallic lithium layer passes through roll-in using lithium bandMode is compounded in the formation of positive electrode active material layer surface, and the quality of metallic lithium layer is the 0.3% of positive active material quality；
The negative electrode tab includes negative current collector copper foil and the negative electrode active material layer that negative current collector two sides are arranged in, instituteStating negative electrode active material layer includes negative electrode active material lithium titanate, conductive agent acetylene black, binder Kynoar (PVDF), titaniumSour lithium, acetylene black, Kynoar mass ratio be 92:4.5:3.5.
The present embodiment can low temperature charging lithium-ion capacitor preparation method, including the following steps:
1) take positive electrode active material activated carbon, conductive agent Super P and binder butadiene-styrene rubber, carboxymethyl cellulose uniformMixing, is made anode sizing agent, the both side surface using coater in plus plate current-collecting body aluminium foil, 120 DEG C of drying, and roll-in is formedPositive electrode active material layer (overall thickness of collector and positive electrode active material layer is 250 μm), slitting；Lithium band is stacked and is laid on justPole active material layer surface, in 50kg/cm2Pressure lower roll swaging at lithium metal layer, obtain positive plate；
It takes negative electrode active material lithium titanate, acetylene black, binder Kynoar uniformly to mix, negative electrode slurry is made, adoptsWith coater in the both side surface of negative current collector copper foil, after 120 DEG C of drying, coating layer thickness is 220 μm, and roll-in forms negativePole active material layer obtains the negative electrode tab with a thickness of 100 μm, and trimming, cut-parts, slitting is wound, spare；
2) diaphragm and electrolyte are taken, diaphragm is microporous polypropylene membrane；Lithium salts used in electrolyte is lithium hexafluoro phosphate, hexafluoro phosphorusThe concentration of sour lithium in the electrolytic solution is 1.2mol/L, and organic solvent used is ethylene carbonate, propene carbonate, dimethyl carbonateThe mixed solvent mixed according to volume ratio 3:1:4；
Takeup type battery core is made in gained positive plate, diaphragm, negative electrode tab, enters shell, injects electrolyte, standing (records quiet for 24 hoursPostpone voltage value, after standing voltage value be 0.5~0.6V), 0.5V constant-current charge to 2.8V is melted into, exhaust molding to getThe lithium-ion capacitor.
Embodiment 4-7 can low temperature charging lithium-ion capacitor in, positive active material type, metallic lithium layer (inertiaLithium powder) it is as shown in table 1 with the mass ratio relationship of positive active material, remaining is the same as embodiment 1.
The mass ratio of positive active material type in 1 embodiment 4-7 of table, metallic lithium layer and positive active material
| Project | Embodiment 4 | Embodiment 5 | Embodiment 6 | Embodiment 7 (mass ratio) |
| Positive active material | Charcoal-aero gel | Activated carbon fibre | Graphene | Active carbon: graphene=1:1 mixing material |
| Li/Na | 0.4% | 0.8% | 1.0% | 0.6% |
Note: Li/NaQuality for metallic lithium layer (inertia lithium powder) is the percentage of positive active material quality.
Embodiment 8-11 can low temperature charging lithium-ion capacitor in, positive active material type, metallic lithium layer (lithiumNet) it is as shown in table 2 with the mass ratio relationship of positive active material, remaining is the same as embodiment 2.
The mass ratio of positive active material type in 2 embodiment 8-11 of table, metallic lithium layer and positive active material
| Project | Embodiment 8 | Embodiment 9 | Embodiment 10 | Embodiment 11 (mass ratio) |
| Positive active material | Charcoal-aero gel | Activated carbon fibre | Graphene | Active carbon: graphene=1:1 mixing material |
| Li/Na | 0.3% | 0.7% | 0.9% | 0.5% |
Note: Li/NaQuality for metallic lithium layer (lithium net) is the percentage of positive active material quality.
Embodiment 12-15 can low temperature charging lithium-ion capacitor in, positive active material type, metallic lithium layer (lithiumBand) it is as shown in table 3 with the mass ratio relationship of positive active material, remaining is the same as embodiment 3.
The mass ratio of positive active material, metallic lithium layer and positive active material in 3 embodiment 12-15 of table
| Project | Embodiment 12 | Embodiment 13 | Embodiment 14 | Embodiment 15 (mass ratio) |
| Positive active material | Charcoal-aero gel | Activated carbon fibre | Graphene | Active carbon: graphene=1:1 mixing material |
| Li/Na | 0.3% | 0.7% | 0.9% | 0.5% |
Note: Li/NaQuality for metallic lithium layer (lithium band) is the percentage of positive active material quality.
Experimental example
This experimental example tests the performance of lithium-ion capacitor obtained by embodiment 1-15 as follows.
(1) static capacity is tested
At 20~30 DEG C, 2.8V is charged to 10A, shelves 15s, 10A is discharged to 0.5V, recycles 5 weeks, is averaged.
(2) forthright test again.
At 20~30 DEG C, in 0.5~2.8V, with 50C multiplying power constant current discharge, and calculates discharge capacity and put relative to 1CThe conservation rate of capacitance.
(3) cycle life is tested.
At 20~30 DEG C, in 0.5~2.8V, 15A constant current charge-discharge is recycled 100,000 times, and is calculated last time and putConservation rate of the capacitance relative to discharge capacity for the first time.
(4) low temperature charging measurement.
At -40 DEG C, in 0.5~2.8V, the test of 15A constant current charge.
Test result is as shown in table 4.
The performance of lithium ion battery test result of 4 embodiment 1-15 of table
Note: Li/NaQuality for metallic lithium layer is the percentage of positive active material quality.
From table 4, it can be seen that when the 50C multiplying power discharging capacity retention ratio of lithium-ion capacitor obtained by embodiment 1-15 is 1C93%~96%, 10 Wan Cihou capacity retention ratios of circulation still reach 84%~89%, -40 DEG C of charging conservation rates 73%~78%.Test result shows that there is lithium ion battery of the invention preferable multiplying power discharging capacity retention ratio, circulation volume to keepRate and low temperature charging conservation rate, have preferable chemical property；While realizing low temperature charging, there is wider work electricityBetween pressure area and higher energy density.