[background technology]:
In recent years, the use of portable power tool and electronic toy is more and more wider, also receives publicity day by day as the battery of energy resource supply.What general traditional electric tool and electronic toy used is alkaline secondary cells such as nickel separation cell and Ni-MH battery, but day by day in the evolution of miniaturization, require the more excellent secondary cell of operating weight energy density and volume energy density gradually at portable power tool and electronic toy.Wherein, lithium ion battery be develop weight energy density and the more excellent secondary cell of volume energy density faster.The part but the lithium ion battery of prior art also comes with some shortcomings.
Multiplying power, heavy-current discharge performance still have much room for improvement at first, greatly.The discharge performance of lithium ion battery is mainly by ionic conducting property and electronic conductivity decision, when discharge, positively charged lithium ion is deviate from from the negative plate carbon-coating, by barrier film between the positive/negative plate and electrolyte, arrive positive plate, positive charge is assembled on the collector of positive plate, electronegative electronics is assembled on the collector of negative plate simultaneously, and the lug by connecting collector and external circuit electron transport to the outside with on the electric line, the final positive plate that arrives has formed the electric current from the positive pole to the negative pole.Metal shell lithium ion battery of the prior art, conventional based lithium-ion battery positive plate thickness are 140-160 μ m, and negative plate thickness is 150-170 μ m.Because the Thickness Design of positive/negative plate must be thicker, the amount of both positive and negative polarity active material on the unit are collector (being both positive and negative polarity active material surface density) is bigger, after having increased lithium ion and deviating from from the negative plate carbon-coating, arrive the distance of positive plate by barrier film between the both positive and negative polarity and electrolyte, the ionic conduction resistance is bigger, influence the ionic conduction ability, thereby influenced the big multiplying power of battery, heavy-current discharge performance.Core adopts the strip takeup type, positive/negative plate links to each other collector by a lug respectively with external circuit, lug generally is welded on an end of strip collector, the electronics of the collector other end need could arrive the lug welding ends by long distance, and be transported to the outside with on the electric line, also influenced its discharge performance.
Secondly, poor safety performance.Be applied in the big multiplying power of battery request, the heavy-current discharge in electric tool and electronic toy field, the caloric value of battery is big, and internal temperature of battery raises many, can reach 50 degree or higher temperature.At high temperature, the liquid state of lithium ion battery has the side reaction between machine battery liquid and positive/negative plate to quicken, and produces portion gas.The lithium ion battery of prior art as shown in Figure 2, its structure comprise long strip type positive plate 1, long strip type negative plate 2, barrier film 3, metal shell 4, owing to adopt the rigid metal shell, morphotropism is poor, and the savings of inside battery gas increases inner pressure of battery.Interior increase of pressing is squeezed Battery Pole Core.In the manufacture process of battery, it is several microns salient point that there are a lot of height sometimes in the surface of positive/negative plate, under the extruded situation of Battery Pole Core, the barrier film that is arranged between the positive/negative plate might be punctured or scratch by these salient points, cause the positive/negative plate contact short circuit, produce a large amount of heats, occur smoldering, safety problem such as burning, on fire or blast.
Certainly, polymer Li-ion battery had as shown in Figure 1 appearred in recent years, its structure comprises short-movie type positive plate 1, short-movie type negative plate 2, polymer dielectric film 3, package compound film shell 4, owing to adopted package compound film shell and gel state electrolyte or plasticising type electrolyte, improved the security performance of battery greatly.But, because gel state or the electrolytical ionic conductivity of plasticising type are low, limited its big multiplying power discharging, still can not satisfy the instructions for use of electric tool and electronic toy well.
[summary of the invention]:
Purpose of the present invention is exactly that providing a kind of at first is that big multiplying power discharging property is good, further the excellent Large Ratio Lithium-Ion Rechargeable Battery of fail safe in order to overcome the above problems.
For achieving the above object, the present invention proposes a kind of Large Ratio Lithium-Ion Rechargeable Battery, comprise shell 4 and be encapsulated in inner core body and electrolyte, described core body comprises positive plate 1, negative plate 2 and isolates the barrier film 3 of described positive/negative plate, comprises collector in the described positive/negative plate; The thickness of described positive plate is 50 microns, and the thickness of described negative plate is 60 microns.
Further, described positive and negative plate is preferably the short-movie type, and core body is a laminated structure.
In the above-mentioned Large Ratio Lithium-Ion Rechargeable Battery, described shell 4 is the package compound film, and described electrolyte is non-water liquid electrolyte.
Above-mentioned Large Ratio Lithium-Ion Rechargeable Battery, the preferred aluminium foil of the collector of described positive plate, the preferred Copper Foil of the collector of described negative plate.
Adopt above scheme, its beneficial effect is:
Because lithium rechargeable battery positive/negative plate thickness of the present invention has the design of optimization, positive plate thickness is 50 μ m, and negative plate thickness is 60 μ m; Than conventional based lithium-ion battery positive plate thickness is 140-160 μ m, negative plate thickness is 150-170 μ m, because the Thickness Design of positive/negative plate must be thinner, the amount of both positive and negative polarity active material on the unit are collector (being both positive and negative polarity active material surface density) is smaller, after having reduced lithium ion and deviating from from the negative plate carbon-coating, arrive the distance of positive plate by barrier film between the both positive and negative polarity and electrolyte, reduced the ionic conduction resistance, strengthen the ionic conduction ability, thereby improved the big multiplying power of battery, heavy-current discharge performance.In the unit volume core body, the area of positive/negative plate improves greatly simultaneously, and the ionic conduction area increases, thereby has improved the big multiplying power of battery, heavy-current discharge performance.
Lithium rechargeable battery positive/negative plate of the present invention further is optimized for short-movie shape structure, the positive electrode plate and negative electrode plate of lithium ion battery of prior art is the strip structure, positive/negative plate links to each other collector by a lug respectively with external circuit, lug generally is welded on an end of strip collector, the electronics of the collector other end need could arrive the lug welding ends by long distance, and is transported to outside with on the electric line.Short-movie shape structure Design is all welded each short-movie with lug, electronics is assembled on collector and exported the required distance of passing through and shorten greatly, has strengthened the electron conduction ability, thereby has improved the big multiplying power of battery, heavy-current discharge performance.
Lithium rechargeable battery of the present invention adopts the package compound film of being made up of macromolecule membrane and metal forming as shell, this distortion of materials is good, the savings of inside battery gas is outwards heaved battery case, thereby avoided the increase of inner pressure of battery, avoided Battery Pole Core to be squeezed, avoided causing the positive/negative plate contact short circuit, thus safety problems such as having avoided producing smolders, burning, on fire or blast.
Lithium rechargeable battery of the present invention adopts non-aqueous electrolyte, and the resistance that lithium ion is subjected to by non-aqueous electrolyte with when having the barrier film of microcellular structure is little, and ionic conductivity is higher, is more suitable in big multiplying power, heavy-current discharge.
The collector of lithium-ion secondary battery positive plate of the present invention is an aluminium foil; The collector of negative plate is a Copper Foil, and the collector of polymer Li-ion battery positive plate compared to prior art is that the collector of nickel screen, negative plate is a copper mesh; Contact-making surface increases, and helps electronics to assemble on collector, has strengthened the electron conduction ability, thereby has improved the big multiplying power of battery, heavy-current discharge performance.
[embodiment]:
Also the present invention is described in further detail in conjunction with the accompanying drawings below by specific embodiment.
Embodiment 1
Lithium and cobalt oxides, companion's form slurry is stirred in the black conductive agent of alkynes, PVDF polyvinylidene fluoride binding agent, NMP n-formyl sarcolysine base pyrrolidones solvent and heating, be coated on the thick aluminium foil of 0.02mm, after baking, cut into the strip of 54*880mm. being pressed into thickness at last is the positive plate 1 of 50 μ m.
Native graphite, the black conductive agent of alkynes, PVDF binding agent, nmp solvent mix and companion's form slurry is stirred in heating, are coated on the thick Copper Foil of 0.012mm, cut into the strip of 55*840mm after baking. being pressed into thickness at last is the negative plate 2 of 60 μ m.
Be wound into the core body that outside dimension is 3.2*40*57mm after PE barrier film 3, positive plate 1 and negative plate 2 stacked by the order of barrier film 3/ positive plate 1/ barrier film 3/ negative plate 2.
The package compound film with PET polyester/NY nylon/AL aluminium foil/CPP hydrostomia polypropylene multi-layer structure that is made of macromolecule membrane and metal forming is struck out the shell 4 that has the 3.5*40*57mm groove, above-mentioned core body is put into shell, inject the non-aqueous electrolyte that constitutes by LiPF6 lithium hexafluoro phosphate and EC dimethyl carbonate, DEC carbonic acid alkene ester, DMC carbonic acid diene ester equal solvent then.At last through encapsulation, change into, operation such as partial volume, the capacity of obtaining is 800mAh, outside dimension is the structure lithium rechargeable battery as shown in Figure 3 of 3.8*42*62mm.
Embodiment 2
Lithium and cobalt oxides, companion's form slurry is stirred in the black conductive agent of alkynes, PVDF polyvinylidene fluoride binding agent, NMP n-formyl sarcolysine base pyrrolidones solvent and heating, be coated on the thick aluminium foil of 0.02mm, after baking, cut into the strip of 54*520mm. being pressed into thickness at last is the positive plate 1 of 100 μ m.
Native graphite, the black conductive agent of alkynes, PVDF binding agent, nmp solvent mix and companion's form slurry is stirred in heating, are coated on the thick Copper Foil of 0.012mm, cut into the strip of 55*480mm after baking. being pressed into thickness at last is the negative plate 2 of 110 μ m.
Making capacity according to embodiment 1 described follow-up operation is 800mAh, and outside dimension is the lithium rechargeable battery as shown in Figure 3 of 3.8*42*62mm.
Embodiment 3
Lithium and cobalt oxides, the black conductive agent of alkynes, PVDF binding agent, nmp solvent mix and companion's form slurry is stirred in heating, are coated on the thick aluminium foil of 0.02mm, cut into the short-movie shape of 54*40mm after baking, being pressed into thickness at last is the positive plate 1 of 100 μ m.
Native graphite, the black conductive agent of alkynes, PVDF binding agent, nmp solvent mix and companion's form slurry is stirred in heating, are coated on the thick Copper Foil of 0.012mm, cut into the short-movie shape of 55*40mm after baking, being pressed into thickness at last is the negative plate 2 of 110 μ m.
PE barrier film 3, positive plate and negative plate are stacked the back successively by the order of barrier film 3/ positive plate 1/ barrier film 2/ negative plate 1/ barrier film 3/ positive plate 1/ barrier film 3/ negative plate 2, and to become outside dimension be the core body of 3.2*40*57mm.
Making capacity according to embodiment 1 described follow-up operation is 800mAh, and outside dimension is the lithium rechargeable battery of the structure as shown in Figure 4 of 3.8*42*62mm.
Embodiment 4
Lithium and cobalt oxides, the black conductive agent of alkynes, PVDF binding agent, nmp solvent mix and companion's form slurry is stirred in heating, are coated on the thick aluminium foil of 0.02mm, cut into the short-movie shape of 54*40mm after baking, being pressed into thickness at last is the positive plate 1 of 140 μ m.
Native graphite, the black conductive agent of alkynes, PVDF binding agent, nmp solvent mix and companion's form slurry is stirred in heating, are coated on the thick Copper Foil of 0.012mm, cut into the short-movie shape of 55*40mm after baking, being pressed into thickness at last is the negative plate 2 of 150 μ m.
PE barrier film 3, positive plate 1 and negative plate 2 are stacked the back successively by the order of barrier film 3/ positive plate 1/ barrier film 3/ negative plate 2/ barrier film 3/ positive plate 1/ barrier film 3/ negative plate 2, and to become outside dimension be the core body of 3.2*40*57mm.
Making capacity according to embodiment 1 described follow-up operation is 800mAh, and outside dimension is the lithium rechargeable battery of the structure as shown in Figure 4 of 3.8*42*62mm.
Comparative example 1
Lithium and cobalt oxides, the black conductive agent of alkynes, PVDF binding agent, nmp solvent mix and companion's form slurry is stirred in heating, are coated on the thick aluminium foil of 0.02mm, cut into the strip of 54*360mm after baking. be pressed into the positive plate that thickness is 145 μ m at last.
Native graphite, the black conductive agent of alkynes, PVDF binding agent, nmp solvent mix and companion's form slurry is stirred in heating, are coated on the thick Copper Foil of 0.012mm, cut into the strip of 55*320mm after baking. be pressed into the negative plate that thickness is 165 μ m at last.
Be wound into the core body that outside dimension is 3.2*40*57mm after PE barrier film, positive plate and negative plate stacked by the order of barrier film/positive plate/barrier film/negative plate.
Above-mentioned core body is put in the aluminum metal case that outside dimension is 3.8*42*60mm, injected the non-aqueous electrolyte that constitutes by LiPF6 and EC, DEC, DMC equal solvent then.At last through sealing, change into, operation such as partial volume, the capacity of obtaining is 800mAh, outside dimension is the lithium rechargeable battery of 3.8*42*60mm.
Comparative example 2
To obtain being of a size of 54*40mm thickness be the positive plate of 145 μ m and be of a size of the negative plate that 55*40mm thickness is 165 μ m according to the method for embodiment 2, and polymer dielectric film, positive plate and negative plate are stacked into the core body that outside dimension is 3.2*40*57mm successively by the order of polymer dielectric film/positive plate/polymer dielectric film/negative plate/polymer dielectric film/positive plate/polymer dielectric film/negative plate.
Above-mentioned core body is put in the package compound film shell that has the 3.5*40*57mm groove, at last through encapsulation, change into, operation such as partial volume, the capacity of making is 800mAh, outside dimension is the polymer lithium ion secondary battery of 3.8*42*62mm.
Six kinds of batteries that make with said method are carried out big multiplying power discharging test and the test of high temperature furnace heat respectively.Method of testing is as follows:
1. big multiplying power discharging test
Use 1C (800mA) constant-current constant-voltage charging 2.5 hours cashier's office in a shop at the lithium electrical testing, charging upper limit 4.2V.After shelving 30 minutes, use 0.2C (160mA), 1C (800mA), 3C (2400mA), 5C (4000mA), 10C (8000mA) to discharge into 3.0V respectively, record discharge capacity, and the ratio of calculating and 0.2C discharge capacity.
Test result sees the following form:
Discharge capacity (mAh) |
0.2C |
1C |
1C/ 0.2C |
3C |
3C/ 0.2C |
5C |
5C/ 0.2C |
10C |
10C/ 0.2C |
Embodiment |
1 |
810 |
805 |
99.4 % |
795 |
98.1 % |
783 |
96.7 % |
718 |
88.6 % |
Embodiment |
2 |
810 |
802 |
99.0 % |
765 |
94.4 % |
710 |
87.6 % |
580 |
71.6 % |
Embodiment |
3 |
810 |
803 |
99.1 % |
780 |
96.3 % |
760 |
93.8 % |
652 |
80.5 % |
Embodiment |
4 |
810 |
801 |
98.9 |
721 |
89.0 |
533 |
65.8 |
426 |
52.6 |
|
|
|
% |
|
% |
|
% |
|
% |
Comparative example 1 |
810 |
800 |
98.8 % |
650 |
80.2 % |
220 |
27.2 % |
80 |
9.9% |
Comparative example 2 |
810 |
798 |
98.5 % |
600 |
74.1 % |
150 |
18.5 % |
40 |
4.9% |
2. high temperature furnace heat test
With lithium electrical testing cabinet battery is full of electricity (800mA constant-current constant-voltage charging 2.5 hours, charging the upper limit 4.2V), then battery is placed in the baking box, make baking box at the uniform velocity be warmed up to 150 ℃, keep 60 fens kinds at 150 ℃ with the programming rate of 5 ± 2 ℃ of per minutes.Phenomenons such as the record battery occurs smoldering after how long keeping in 150 ℃ of baking boxs, burning, on fire, blast.
Test result sees the following form:
|
Retention time | Phenomenon |
Embodiment |
1 |
60 minutes |
Do not have smolder, burning, on fire, explosion phenomenon |
Embodiment |
2 |
60 minutes |
Do not have smolder, burning, on fire, explosion phenomenon |
Embodiment |
3 |
60 minutes |
Do not have smolder, burning, on fire, explosion phenomenon |
Embodiment |
4 |
60 minutes |
Do not have smolder, burning, on fire, explosion phenomenon |
Comparative example 1 |
15 minutes |
Occur smoldering after 15 minutes, burning, on fire, explosion phenomenon |
Comparative example 2 |
60 minutes |
Do not have smolder, burning, on fire, explosion phenomenon |
From above-mentioned test result as can be seen:
1. embodiments of the invention 1 and embodiment 2 are owing to optimize on the positive/negative plate Thickness Design, positive/negative plate thickness is thinner than the Thickness Design of existing lithium battery greatly, thereby is being better than comparative example 1 and comparative example 2 aspect the big multiplying power discharging property of 3C-10C greatly.
2. to design enterprising one-step optimization at positive/negative plate be the short-movie type to embodiments of the invention 3, and core body adopts laminated structure, and big multiplying power discharging property further improves, and is better than the identical embodiment of pole piece thickness 2.
3. embodiments of the invention 4 also are being better than comparative example 1 and comparative example 2 aspect the big multiplying power discharging property of 3C-10C.
4. embodiment 1, embodiment 2, embodiment 3, embodiment 4 are owing to used package compound film shell, and the security performance in hot environment has reached the level of the polymer Li-ion battery of comparative example 2.The lithium ion battery that is better than the use aluminum hull of comparative example 1 greatly.