CN109449447A - Secondary battery - Google Patents
Secondary battery Download PDFInfo
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- CN109449447A CN109449447A CN201811209264.2A CN201811209264A CN109449447A CN 109449447 A CN109449447 A CN 109449447A CN 201811209264 A CN201811209264 A CN 201811209264A CN 109449447 A CN109449447 A CN 109449447A
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- Prior art keywords
- battery
- cathode
- secondary cell
- active material
- pole piece
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/64—Carriers or collectors
- H01M4/66—Selection of materials
- H01M4/665—Composites
- H01M4/667—Composites in the form of layers, e.g. coatings
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
- H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/054—Accumulators with insertion or intercalation of metals other than lithium, e.g. with magnesium or aluminium
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/64—Carriers or collectors
- H01M4/70—Carriers or collectors characterised by shape or form
-
- 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
- Y02E60/10—Energy storage using batteries
Abstract
The invention provides a secondary battery, which comprises a positive pole piece, a negative pole piece, a separation film and electrolyte, wherein the negative pole piece comprises a negative pole current collector and a negative pole diaphragm which is arranged on at least one surface of the negative pole current collector and comprises a negative pole active material, the secondary battery also meets the requirements that 2.90- α -5.10-0.08- β -0.55, α -8 XP + 1.2-A, P represents the porosity of the negative pole diaphragm, A represents the battery capacity excess coefficient, β -D50/H, D50 represents the corresponding particle size when the cumulative volume percentage of the negative pole active material reaches 50%, H represents the thickness of the negative pole diaphragm, and the units of D50 and H are both mum.
Description
Technical field
The present invention relates to field of batteries more particularly to a kind of secondary cells.
Background technique
Rechargeable battery has the prominent spies such as light-weight, energy density is high, pollution-free, memory-less effect, long service life
Point is widely used in the fields such as mobile phone, computer, household electrical appliance, electric tool at present.Wherein, the charging time increasingly by
The attention of terminal consumer, and the key factor that limitation rechargeable battery is universal.
For technical principle, the core of quickly charging battery technology is mentioned by chemical system reconciliation and design optimization
Active ion is risen in the movement speed of positive and negative interpolar.It is living in quickly charging battery if the unbearable large current charge of cathode
Property ion can negative terminal surface be reduced directly be precipitated rather than insertion negative electrode active material in, while in quickly charging battery bear
Pole surface can also generate a large amount of by-products, influence the cycle life and safety of battery.
Therefore how to realize and obtain quick charge capability under the premise of not sacrificing battery energy density, be battery design
Key point.
Summary of the invention
In view of the problems in the background art, the purpose of the present invention is to provide a kind of secondary cells, can make secondary
Battery obtains quick charge capability and long circulation life while not sacrifice energy density.
In order to achieve the above object, the present invention provides a kind of secondary cells comprising anode pole piece, cathode pole piece, every
From film and electrolyte, the cathode pole piece include negative current collector and be arranged at least one surface of negative current collector and
Cathode membrane including negative electrode active material.The secondary cell also meets: 2.90≤α≤5.10,0.08≤β≤0.55.Its
In, α=8 × P+1.2 × A, P indicates the porosity of cathode membrane, and A indicates battery capacity excess coefficient；β=D50/H, D50 table
Show that negative electrode active material cumulative volume percentage reaches partial size corresponding when 50%, H indicates the thickness of cathode membrane, D50 and H
Unit be μm.
Compared with the existing technology, the present invention is including at least as described below the utility model has the advantages that the present invention passes through matching negative electrode film
Relationship between the porosity of piece, battery capacity excess coefficient, anode active material particles size and cathode membrane thickness, can
So that secondary cell while not sacrifice energy density, obtains quick charge capability and long circulation life.
Specific embodiment
The following detailed description of secondary cell according to the present invention.
Secondary cell of the invention includes anode pole piece, cathode pole piece, isolation film and electrolyte, the cathode pole piece packet
It includes negative current collector and is arranged at least one surface of negative current collector and the cathode membrane including negative electrode active material.Institute
It states secondary cell also to meet: 2.90≤α≤5.10,0.08≤β≤0.55.Wherein, α=8 × P+1.2 × A, P indicate negative electrode film
The porosity of piece, A indicate battery capacity excess coefficient；β=D50/H, D50 indicate that negative electrode active material cumulative volume percentage reaches
Corresponding partial size when to 50%, H indicate the thickness of cathode membrane, and the unit of D50 and H are μm.
In battery charging process, for cathode pole piece, need by 3 following electrochemical process: (1) from just
The active ion (such as lithium ion, sodium ion etc.) deviate from the active material of pole enters in electrolyte, and as electrolyte enters
In the duct of cathode porous electrode, liquid phase conduction of the active ion inside duct is carried out；(2) active ion and electronics are in cathode
Active material surface carries out charge-exchange；(3) active ion is conducted from negative electrode active material surface solid phase to negative electrode active material
Inside body phase.
Wherein, quickly charging battery ability and cycle performance are related to the porosity P of cathode membrane, cathode membrane
Porosity P will affect liquid phase conducting power of the active ion inside cathode porous electrode duct.In general, the hole of cathode membrane
Rate P is bigger, and cathode porous electrode cellular structure is more flourishing, and the electrolyte wellability of cathode pole piece is better, and active ion is in cathode
Porous electrode duct internal liquid phase conduction of velocity is higher, and in quickly charging battery, active ion is easier to be embedded in negative electrode active
In substance, while active ion can also be avoided directly to restore precipitation in negative terminal surface and grow dendrite, thus battery fills repeatedly
Irreversible capacity loss is smaller in discharge process, and the cycle life of battery can be longer.But as the porosity P of cathode membrane increases
Add, the energy density loss of battery can be increasingly severe.
Quickly charging battery ability is also related to battery capacity excess coefficient A, and A indicates positive and negative diaphragm face of the same area
When, the ratio between the capacitance of the capacitance of cathode membrane and positive diaphragm, the i.e. capacitor of battery capacity excess coefficient A=cathode membrane
Amount/anode diaphragm capacitance.In general, active ion a part of anode abjection can form SEI film in negative terminal surface, it is remaining
Active ion will be embedded in negative electrode active material, and different battery capacity excess coefficients can make battery expire cathode pole piece when filling to be in
Different SOC states.In general, battery capacity excess coefficient A is bigger, when battery completely fills, the SOC state of cathode pole piece is lower, bears
The volume expansion and side reaction of pole pole piece are fewer, more facilitate to promote quickly charging battery ability and cycle life.But meanwhile
Battery capacity excess coefficient A is bigger, it is meant that the capacitance of cathode membrane is bigger or the capacitance of positive diaphragm is smaller, i.e., negative
It there will more than likely be that excessive active material cannot be utilized effectively or the energy density of anode is lower, therefore will cause battery
Energy density lose increase.
Quickly charging battery ability is also closely bound up with the electrolyte wetting velocity of cathode pole piece.Cathode pole piece is come
It says, electrolyte impregnation process is the process by slowly internally carrying out liquid phase conduction outside cathode pole piece, therefore in addition to negative electrode film
Outside the porosity of piece, the arrangement of cathode porous electrode cellular structure and specific pattern also will affect quickly charging battery ability, follow
Ring service life and energy density.
Inventor also found by numerous studies, and the ratio of anode active material particles size and cathode membrane thickness can be with
Reflect the tortuosity of cathode porous electrode cellular structure.Wherein, the tortuosity of cathode porous electrode cellular structure is smaller, electrolyte
The path for internally carrying out liquid phase conduction outside cathode pole piece with active ion is shorter, the electrolyte wetting velocity of cathode pole piece
Faster, the polarization on negative electrode active material surface is smaller during quickly charging battery, and the dynamic performance of cathode pole piece is better,
The promotion of quickly charging battery ability is also more obvious.But the tortuosity of cathode porous electrode cellular structure is small to a certain extent,
Active ion solid phase conduction resistance inside negative electrode active material plastid phase increases, and quickly charging battery ability will decline, while this
The too low tortuosity design of kind also results in battery energy density and is substantially reduced.
Inventor further study show that, when meet 2.90≤α=8 × P+1.2 × A≤5.10,0.08≤β=D50/H
When≤0.55, the electrolyte wellability and electrolyte wetting velocity of cathode pole piece are more excellent, and active ion is in negative electrode active material
Solid phase conduction velocity and active ion are more excellent in cathode porous electrode internal liquid phase conduction velocity inside plastid phase, secondary cell
Quick charge capability and long circulation life can be obtained while not sacrifice energy density.Wherein, β can indicate that cathode is more
Pore electrod cellular structure feature, β value is bigger, indicates that the tortuosity of cathode porous electrode cellular structure is smaller.
When α (i.e. 8 × P+1.2 × A) is greater than 5.10, the porosity of cathode membrane is relatively large, battery capacity is excessively
Number is relatively large, and the electrolyte wellability of cathode pole piece is fine at this time, and active ion is in cathode porous electrode duct internal liquid phase
Also quickly, cathode pole piece can have good dynamic performance to conduction of velocity, and quickly charging battery ability is also fine, but battery
It is difficult to have both high-energy density advantage, not be able to satisfy currently to the use demand in battery long cruise duration.
When α (i.e. 8 × P+1.2 × A) is less than 2.90, the porosity of cathode membrane is relatively small, battery capacity is excessively
Number is relatively small, and the electrolyte wellability of cathode pole piece is poor at this time, and active ion is in cathode porous electrode duct internal liquid phase
Conduction resistance increases, and cathode will be in higher SOC state, the volume expansion and pair of cathode pole piece during quickly charging battery
Reaction increases, and is not able to satisfy the use demand currently to quickly charging battery ability and cycle life.
In certain embodiments of the present invention, the lower limit value of α (i.e. 8 × P+1.2 × A) can for 2.90,3.00,
3.10,3.20,3.30,3.40,3.50,3.60,3.70,3.80,3.90, the upper limit value of 4.00, α can for 3.80,3.90,
4.00,4.10,4.20,4.30,4.40,4.50,4.60,4.70,4.80,4.90,5.00,5.10.Preferably, 3.70≤α=8
×P+1.2×A≤4.70。
In certain embodiments of the present invention, the lower limit value of β (i.e. D50/H) can for 0.08,0.09,0.10,0.11,
0.12,0.13,0.14,0.15,0.16,0.17, the upper limit value of 0.18, β can for 0.16,0.18,0.20,0.22,0.24,
0.26,0.28,0.30,0.32,0.34,0.36,0.38,0.40,0.42,0.44,0.46,0.48,0.50,0.52,0.55.It is excellent
Selection of land, 0.12≤β=D50/H≤0.48.
In secondary cell of the invention, in general, the porosity of cathode membrane it is excessive or it is too small can be to the circulation of battery
Service life, quick charge capability and energy density produce bigger effect.It is therefore preferred that the porosity P of the cathode membrane is
20%~55%；It is highly preferred that the porosity P of the cathode membrane is 25%~40%.The porosity of cathode membrane is fallen into
When stating in preferred scope, there can be high volume energy density advantage to have both good electrolyte infiltration simultaneously guaranteeing cathode pole piece
Property, at the same cathode membrane possess electrolyte ability it is more preferable, the resistance of interfacial charge transfer between negative electrode active material and electrolyte
Anti- also lower, the quick charge capability and cycle life of battery can be promoted preferably.
In secondary cell of the invention, in general, in the identical situation of other preparation conditions, battery capacity excess coefficient
When smaller, cathode may receive all active ions from anode abjection without enough vacancy in battery charging process, into
And amount of activated ion is easy to restore to be precipitated in negative terminal surface to form dendrite, battery irreversible capacity loss increases, while battery
There is also higher security risks.Battery capacity excess coefficient increases, and the acceptable capacitance of cathode increases, the activity in cathode
Substance total amount can also increase therewith, and liquid phase conducting path can be elongated in cathode porous electrode duct for active ion, battery polarization
Also it can become larger, therefore battery capacity excess coefficient should not be too large, otherwise quickly charging battery capability improving may be generated certain
Degree negative effect, while will also have extra negative electrode active material (the i.e. quickly charging battery of more in cathode pole piece
In the process, increase without the negative electrode active material specific gravity of active ion insertion), it will reduce battery energy density.In addition, battery
Capacity excess coefficient increases, and the capacitance that anode can be deviate from is opposite to be reduced, and positive volume energy density reduces, and can also reduce electricity
Pond energy density.It is therefore preferred that the battery capacity excess coefficient A is 0.8~2.0；It is highly preferred that the battery capacity
Excess coefficient A is 1.1~1.3.When battery capacity excess coefficient is fallen into above-mentioned preferred scope, battery can promoted preferably
High-energy density advantage is kept while quick charge capability.
In secondary cell of the invention, in general, the particle of negative electrode active material is smaller, active ion is in negative electrode active material
Solid phase conduction resistance is smaller inside plastid phase, and the dynamic performance of cathode pole piece is easier to be obviously improved effect, and battery is quick
Charging ability can also be promoted preferably, but battery energy density can also reduce to a certain extent simultaneously.It is therefore preferred that institute
The partial size D50 for stating negative electrode active material is 4 μm~25 μm；It is highly preferred that the partial size D50 of the negative electrode active material be 5 μm~
18μm.It, can be too small more with electrolyte generation to avoid partial size when the partial size of negative electrode active material is fallen into above-mentioned preferred scope
Side reaction and influence the improvement to battery performance, the too big obstruction active ion of partial size can also be avoided in negative electrode active material
Solid phase conducts and influences the improvement to battery performance inside plastid phase.
In secondary cell of the invention, in general, cathode membrane is thicker, battery energy density is higher, but active ion
In cathode porous electrode duct, internal liquid phase conduction resistance can also be increase accordingly, and easier to the dynamic performance of cathode pole piece have
Negative effect, while the promotion of quickly charging battery ability will also become to be less susceptible to.It is therefore preferred that the cathode membrane
Thickness H be 20 μm~100 μm；It is highly preferred that the thickness H of the cathode membrane is 30 μm~80 μm.Cathode membrane thickness is fallen
When entering in above-mentioned preferred scope, battery high energy metric density can be kept excellent while preferably promoting quickly charging battery ability
Gesture.
It should be noted that when cathode membrane is arranged on two surfaces of negative current collector, it is of the present invention " negative
The thickness H " of pole diaphragm refer to negative current collector wherein on any one surface cathode membrane thickness.
In secondary cell of the invention, inventor also found by numerous studies, when the secondary cell also meets 0.4
The comprehensive performance of≤α × β≤2.3, battery can be advanced optimized, battery can preferably have both high-energy density, quickly
Charging ability and long circulation life.
In certain embodiments of the present invention, the lower limit value of α × β can for 0.4,0.5,0.6,0.7,0.8,0.9,
1.0,1.1,1.2, α × β upper limit value can for 1.0,1.1,1.2,1.3,1.4,1.5,1.6,1.7,1.8,1.9,2.0,
2.1,2.2,2.3.It is highly preferred that the secondary cell also meets 0.4≤α × β≤1.8.
In secondary cell of the invention, it is preferable that the negative electrode active material can be selected from carbon material, silica-base material, tin
One or more of sill, lithium titanate.Wherein, the carbon material can be selected from graphite, soft carbon, hard carbon, carbon fiber, interphase
One or more of carbosphere；The graphite can be selected from one or more of artificial graphite, natural graphite；The silicon substrate
Material can be selected from one or more of elemental silicon, silicon oxide compound, silicon-carbon compound, silicon alloy；The tin-based material can be selected from
One or more of simple substance tin, tin oxygen compound, tin alloy.It is highly preferred that the negative electrode active material can be selected from carbon material,
One or more of silica-base material.
In secondary cell of the invention, the cathode membrane be may be provided on one of surface of negative current collector
It can be set on two surfaces of negative current collector.The cathode membrane may also include conductive agent and binder, conductive agent
And the type and content of binder are not particularly limited, and can be selected according to actual needs.The negative current collector
Type is not also particularly limited, and can be selected according to actual needs.
In secondary cell of the invention, the anode pole piece include plus plate current-collecting body and setting plus plate current-collecting body extremely
On a few surface and the positive diaphragm including positive active material, wherein the type and concrete composition of the anode pole piece are equal
It is not limited specifically, can be selected according to actual needs.The anode diaphragm may be provided at plus plate current-collecting body wherein
It also can be set on one surface on two surfaces of plus plate current-collecting body.The anode diaphragm may also include conductive agent and glue
The type and content of knot agent, conductive agent and binder are not particularly limited, and can be selected according to actual needs.It is described just
The type of pole collector is not also particularly limited, and can be selected according to actual needs.
It should be noted that secondary cell of the invention can be lithium ion battery, it can also be sodium-ion battery.
When secondary cell is lithium ion battery: the positive active material is preferably selected from lithium and cobalt oxides, lithium nickel oxygen
Compound, lithium manganese oxide, Li, Ni, Mn oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, olivine structural phosphorus containing lithium
Hydrochlorate etc., but the application is not limited to these materials, other can also be used to be used as lithium ion cell positive active matter
The conventional known material of matter.One kind can be only used alone in these positive active materials, two or more combinations can also be made
With.Preferably, positive active material can be chosen in particular from LiCoO2、LiNiO2、LiMnO2、LiMn2O4、LiNi1/3Co1/3Mn1/3O2
(NCM333)、LiNi0.5Co0.2Mn0.3O2(NCM523)、LiNi0.6Co0.2Mn0.2O2(NCM622)、LiNi0.8Co0.1Mn0.1O2
(NCM811)、LiNi0.85Co0.15Al0.05O2、LiFePO4、LiMnPO4One or more of.
When secondary cell is sodium-ion battery: the positive active material is preferably selected from transition metal oxide
NaxMO2(M is transition metal, is preferably selected from one or more of Mn, Fe, Ni, Co, V, Cu, Cr, 0 < x≤1), polyanion
Material (phosphate, fluorophosphate, pyrophosphate, sulfate), Prussian blue material etc., but the application is not limited to these materials
Material, the application can also use other to be used as the conventional known material of sodium-ion battery positive active material.These are just
One kind can be only used alone in pole active material, can also be used in combination of two or more.Preferably, positive active material can have
Body is selected from NaFeO2、NaCoO2、NaCrO2、NaMnO2、NaNiO2、NaNi1/2Ti1/2O2、NaNi1/2Mn1/2O2、Na2/3Fe1/3Mn2/ 3O2、NaNi1/3Co1/3Mn1/3O2、NaFePO4、NaMnPO4、NaCoPO4, Prussian blue material, general formula AaMb(PO4)cOxY3-x's
(wherein A is selected from H to material+、Li+、Na+、K+、NH4+One or more of, M is transition-metal cation, be preferably selected from V, Ti,
One or more of Mn, Fe, Co, Ni, Cu, Zn, Y are halide anion, are preferably selected from one or more of F, Cl, Br, 0
One or more of < a≤4,0 <b≤2,1≤c≤3,0≤x≤2).
In secondary cell of the invention, the type of the isolation film is not exposed to specific limitation, can be existing electricity
Any barrier material used in pond, such as polyethylene, polypropylene, Kynoar and their multilayer complex films, but
It is not limited only to these.
In secondary cell of the invention, the electrolyte may include electrolyte salt and organic solvent, wherein electrolyte
The specific type and composition of salt and organic solvent are not limited specifically, can be selected according to actual needs.The electricity
Solution liquid may also include additive, and the additive types are not particularly limited, and can be cathode film for additive, can also be positive
Pole film for additive can also be that can improve the additive of the certain performances of battery, such as improve the addition of over-charging of battery performance
Agent, the additive for improving battery high-temperature behavior, the additive for improving battery cryogenic property etc..
It should be noted that when cathode membrane is arranged on two surfaces of negative current collector, wherein negative current collector
Cathode membrane parameter on any one upper surface meets 2.90≤α≤5.10,0.08≤β≤0.55, that is, thinks that the battery is fallen
Enter in protection scope of the present invention.
Below by taking lithium ion battery as an example, in conjunction with specific embodiments, the application is further described.It should be understood that these implementations
Example is merely to illustrate the application rather than limitation scope of the present application.
Embodiment 1
(1) preparation of anode pole piece
In mass ratio by positive active material (see Table 1 for details), conductive agent Super P, binder Kynoar (PVDF)
96:2:2 is mixed, and is added solvent N-methyl pyrilidone (NMP), and stirring is to system in uniform under de-airing mixer effect
Shape obtains anode sizing agent；Anode sizing agent is coated uniformly on plus plate current-collecting body aluminium foil, room temperature is transferred to baking oven continuation after drying
It is dry, then anode pole piece is obtained by cold pressing, cutting.
(2) preparation of cathode pole piece
By negative electrode active material (see Table 1 for details), conductive agent Super P, thickener sodium carboxymethylcellulose (CMC), bonding
After agent butadiene-styrene rubber (SBR) 96.4:1:1.2:1.4 in mass ratio mixing, solvent deionized water is added, is acted in de-airing mixer
Lower stirring to system is in uniform shape, obtains negative electrode slurry；Negative electrode slurry is coated uniformly on negative current collector copper foil, room temperature is dried in the air
Baking oven is transferred to after dry and continues drying, then obtains cathode pole piece by cold pressing, cutting.Wherein, pass through control cold pressure procedure ginseng
The porosity P of number (such as cold pressing pressure, cold pressing speed etc.) the adjustable cathode membrane and thickness H of cathode membrane.
(3) preparation of electrolyte
Ethylene carbonate (EC), dimethyl carbonate (DMC), diethyl carbonate (DEC) are carried out according to 1:1:1 by volume
It is mixed to get organic solvent, then by sufficiently dry lithium salts LiPF6It is dissolved in mixed organic solvent, is configured to concentration
For the electrolyte of 1mol/L.
(4) preparation of isolation film
Select polyethylene film as isolation film.
(5) preparation of lithium ion battery
Above-mentioned anode pole piece, isolation film, cathode pole piece are folded in order, are in isolation film between positive and negative electrode pole piece
Play the role of isolation, then winding obtains naked battery core；Naked battery core is placed in outer packing shell, injects electrolyte after dry, is passed through
The processes such as Vacuum Package, standing, chemical conversion, shaping are crossed, lithium ion battery is obtained.
The lithium ion battery of embodiment 2-14 and comparative example 1-6 are prepared according to method similar to Example 1,
Specific difference is shown in table 1.
Table 1: the parameter of embodiment 1-14 and comparative example 1-6
The performance test of cathode pole piece and battery will be illustrated next.
1, each parameter testing of cathode pole piece
(1) the partial size D50 of negative electrode active material
The partial size D50 of negative electrode active material can be by using laser diffraction granularity distribution measuring apparatus (such as Mastersizer
3000) particle diameter distribution is measured, D50 indicates that negative electrode active material cumulative volume percentage reaches partial size corresponding when 50%.
(2) the porosity P of cathode membrane
The porosity P of cathode membrane can be obtained by gas displacement method, porosity P=(V1-V2)/V1× 100%, V1Table
Show apparent volume, V2Indicate true volume.
(3) the thickness H of cathode membrane
The thickness H of cathode membrane can be used tenthousandth micrometer measurement and obtain, such as usable model Mitutoyo293-100,
Precision is that 0.1 μm of tenthousandth micrometer measurement obtains.Cathode membrane thickness of the present invention refers to after cold pressing compacting and for group
The thickness of cathode membrane in the cathode pole piece of packed battery.
(4) battery capacity excess coefficient A
1. the capacitance of unit area anode diaphragm is tested
Step 1): the battery containing each embodiment and the anode pole piece of comparative example is completely put, and is stood after five minutes, is charged to
Blanking voltage, wherein charging process is specially with 1/3C constant-current charge to blanking voltage, then again with blanking voltage constant-voltage charge
To 0.03C, the charging capacity C at this time obtained0The discharge capacity of as positive diaphragm.
Step 2): measuring and calculates the gross area of positive diaphragm (gross area herein refers to spreading area；If two-sided painting
The spreading area on two sides need to be added by cloth).
Step 3): according to the capacitance of positive diaphragm unit area=anode diaphragm discharge capacity (mAh)/anode diaphragm
The gross area (cm2), the capacitance of positive diaphragm unit area is calculated.
2. the capacitance of unit area cathode membrane is tested
Step 1): taking the cathode pole piece of the various embodiments described above and comparative example, is obtained using Lamination mould certain area, single
The cathode sequin of face coating.It is to electrode, Celgard film as isolation film, dissolved with LiPF using metal lithium sheet6(concentration 1mol/
L the solution of EC+DMC+DEC (volume ratio 1:1:1)) is electrolyte, and 6 CR2430 types are assembled in the glove box of argon gas protection
Button cell.Button batteries stand 12h after installing, and constant-current discharge is carried out under the discharge current of 0.05C, until voltage is
Then 5mV carries out constant-current discharge with the discharge current of 50 μ A again, until voltage be 5mV, then carried out with the discharge current of 10 μ A
Constant-current discharge, until voltage is 5mV, standing 5 minutes finally carries out constant-current charge, until final under the charging current of 0.05C
Voltage is 2V, records charging capacity.The average value of 6 button cell charging capacitys is the average capacitance amount of cathode membrane.
Step 2): using the diameter d of calliper to measure cathode sequin, and the area of cathode sequin is calculated.
Step 3): according to the capacitance of cathode membrane unit area=cathode sequin average capacitance amount (mAh)/cathode
Area (the cm of sequin2), the capacitance of cathode membrane unit area is calculated.
3. capacitance (mAh)/unit area anode diaphragm of battery capacity excess coefficient A=unit area cathode membrane
Capacitance (mAh).
2, the performance test of battery
(1) dynamic performance is tested
At 25 DEG C, after the battery that embodiment and comparative example is prepared completely is filled with x C, is completely put and is repeated 10 times with 1C,
Battery is completely filled with x C again, then disassemble out cathode pole piece and observes the analysis lithium situation on cathode pole piece surface.If negative terminal surface
Lithium is not analysed, then rate of charge x C is incremented by using 0.1C as gradient and is tested again, until negative terminal surface analyses lithium, stops test,
Rate of charge x C at this time subtracts the maximum charge multiplying power that 0.1C is battery.
(2) cycle performance is tested
At 25 DEG C, the battery that embodiment and comparative example is prepared is charged with 3C multiplying power, with 1C multiplying power discharging, is carried out
Full be full of puts loop test, until the capacity of battery is less than the 80% of initial capacity, records the circulating ring number of battery.
(3) actual energy density measurement
At 25 DEG C, the battery that embodiment and comparative example is prepared completely is filled with 1C multiplying power, is completely put with 1C multiplying power, recorded
Actual discharge energy at this time；At 25 DEG C, weighed using electronic balance to the battery；Battery 1C actual discharge energy with
The ratio of battery weight is the actual energy density of battery.
Wherein, when actual energy density is less than the 80% of target energy density, it is believed that battery actual energy density is very low；
When actual energy density is more than or equal to the 80% of target energy density and is less than the 95% of target energy density, it is believed that battery is practical
Energy density is relatively low；Actual energy density is more than or equal to the 95% of target energy density and is less than the 105% of target energy density
When, it is believed that battery actual energy medium density；Actual energy density is more than or equal to the 105% of target energy density and is less than target
Energy density 120% when, it is believed that battery actual energy density is higher；Actual energy density is the 120% of target energy density
When above, it is believed that battery actual energy density is very high.
Table 2: the performance test results of embodiment 1-14 and comparative example 1-6
From the test result of table 2 it can be seen that the battery of embodiment 1-14 simultaneously meet 2.90≤α=8 × P+1.2 ×
A≤5.10,0.08≤β=D50/H≤0.55, the electrolyte wellability and electrolyte wetting velocity of cathode pole piece are more excellent,
Lithium ion solid phase conduction velocity and lithium ion inside negative electrode active material plastid phase conduct fast in cathode porous electrode internal liquid phase
Rate is more excellent, therefore battery can obtain quick charge capability and long circulation life while not sacrifice energy density.
Compared with embodiment 1-14, in comparative example 1-6, each battery is no while meeting 2.90≤α=8 × P+1.2
× A≤5.10 and 0.08≤β=D50/H≤0.55, battery can not have both simultaneously higher energy density, quick charge capability and
Long circulation life.
Wherein, the porosity P of cathode membrane is preferably 20%~55%, when in above-mentioned preferred scope, can guarantee to bear
There is pole pole piece high volume energy density advantage to have both good electrolyte wellability simultaneously, and cathode membrane possesses the energy of electrolyte
Power is more preferable, and the interfacial charge transfer impedance between negative electrode active material and electrolyte is also lower, quickly charging battery ability with
And cycle life can be promoted further.Battery capacity excess coefficient A is preferably 0.8~2.0, in above-mentioned preferred scope
When, battery can keep high-energy density advantage while preferably promoting quick charge capability.The grain of negative electrode active material
Diameter D50 is preferably 4 μm~25 μm, when in above-mentioned preferred scope, and the homogeneity of cathode pole piece is higher, can be too small to avoid partial size
Generate more side reaction with electrolyte and influence the improvement to battery performance, can also avoid the too big obstruction lithium of partial size from
Solid phase of the son inside negative electrode active material plastid phase conducts and influences the improvement to battery performance.The thickness H of cathode membrane
Preferably 20 μm~100 μm, it is possible thereby to keep battery high energy amount close while preferably promoting quickly charging battery ability
Degree advantage.
But work as porosity P, the battery capacity excess coefficient A, the partial size D50 of negative electrode active material, negative electrode film of cathode membrane
When one or several parameters in the thickness H of piece are not able to satisfy above-mentioned preferred scope, as long as guarantee 2.90≤α=8 × P+1.2 ×
A≤5.10,0.08≤β=D50/H≤0.55,9-10, battery can still obtain while not sacrifice energy density in conjunction with the embodiments
Obtain relatively high quick charge capability and relatively long cycle life.
From embodiment 11-14 and comparative example 3-6 it is found that when the different positive and negative electrode active material of Selection of Battery, only
Meet 2.90≤α=8 × P+1.2 × A≤5.10 and 0.08≤β=D50/H≤0.55, it is close that battery can still have both high-energy
Degree, quick charge capability and long circulation life.
Further, when battery is meeting 2.90≤α=8 × P+1.2 × A≤5.10 and 0.08≤β=D50/H≤0.55
Under the premise of, when 0.4≤α of further satisfaction × β≤2.3, the comprehensive performance of battery can be advanced optimized, and battery can be more
High-energy density, quick charge capability and long circulation life are had both well.
According to the disclosure and teachings of the above specification, those skilled in the art can also change above embodiment
And modification.Therefore, the invention is not limited to the specific embodiments disclosed and described above, to some modifications of the invention and
Change should also be as falling into the scope of the claims of the present invention.In addition, although having been used in this specification some specific
Term, these terms are merely for convenience of description, does not limit the present invention in any way.
Claims (10)
1. a kind of secondary cell, including anode pole piece, cathode pole piece, isolation film and electrolyte, the cathode pole piece includes negative
Pole collector and it is arranged at least one surface of negative current collector and the cathode membrane including negative electrode active material；
It is characterized in that,
The secondary cell meets: 2.90≤α≤5.10,0.08≤β≤0.55；
Wherein,
α=8 × P+1.2 × A, P indicate the porosity of cathode membrane, and A indicates battery capacity excess coefficient；
β=D50/H, D50 indicate that negative electrode active material cumulative volume percentage reaches partial size corresponding when 50%, and H indicates negative
The unit of the thickness of pole diaphragm, D50 and H are μm.
2. secondary cell according to claim 1, which is characterized in that 3.70≤α≤4.70.
3. secondary cell according to claim 1, which is characterized in that 0.12≤β≤0.48.
4. secondary cell according to claim 1, which is characterized in that the porosity P of the cathode membrane be 20%~
55%, preferably 25%~40%.
5. secondary cell according to claim 1, which is characterized in that the battery capacity excess coefficient A is 0.8~2.0,
Preferably 1.1~1.3.
6. secondary cell according to claim 1, which is characterized in that the partial size D50 of the negative electrode active material be 4 μm~
25 μm, preferably 5 μm~18 μm.
7. secondary cell according to claim 1, which is characterized in that the thickness H of the cathode membrane is 20 μm~100 μ
M, preferably 30 μm~80 μm.
8. secondary cell described in any one of -7 according to claim 1, which is characterized in that the secondary cell also meets: 0.4
≤α×β≤2.3。
9. secondary cell according to claim 8, which is characterized in that the secondary cell also meets: 0.4≤α × β≤
1.8。
10. secondary cell according to claim 1, which is characterized in that
The negative electrode active material is selected from one or more of carbon material, silica-base material, tin-based material, lithium titanate；
Preferably, the negative electrode active material is selected from one or more of carbon material, silica-base material.
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| WO2020078361A1 (en) | 2020-04-23 |
| CN109449447B (en) | 2021-01-15 |
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