Storage battery is with conduction connector and storage battery
Technical field
The invention discloses a kind of storage battery with conduction connector and by this conduction connector with the storage battery that each cell is formed by connecting, be mainly used in used for electric vehicle storage battery field.
Background technology
From environmental protection and energy-conservation angle, the electric automobile of development cleanliness without any pollution has become a breach of various countries' auto industry.Electric automobile has the unrivaled advantage of traditional fuel-engined vehicle, such as: the electric automobile noise is low, pollutant emission can reduce 97%, energy variation, efficiency height, the electric automobile energy utilance is 17.8%, the capacity usage ratio of fuel-engined vehicle only is 10.3%, can save about 40% oil.So electric automobile will become the most potential vehicles of 21 century.
According to industry prediction, the oil electricity mixes motor-car (Hybrid Electric Vehicle is called for short HEV) can reach 6,000,000 at the sales volume of US and European automobile market in 10 years.Mix the motor-car sales volume and account for 0.5% of world car total output at present.Now, most of motor-car that mixes adopts Ni-MH battery, and lithium ion battery has great potential, can be widely used in following mixed motor-car.Because of its in volume, weight, advantage on the life-span, lithium ion battery is expected to become following main flow.
The power supply that electric automobile is developing on using mainly contains sodium-sulphur battery, Ni-MH battery, lithium ion battery, metal (zinc or aluminium) air cell, fuel cell, flying wheel battery etc., the application of these novel power supplies is for wide prospect has been opened up in the development of electric automobile.At present, the novel battery of having used on electric automobile mainly is divided into two big classes: Ni-MH battery and lithium ion battery.The lithium battery ion is with its high voltage, high-energy-density, memory-less effect and the tool clear superiority will become the market mainstream.The commercial battery that is used for electric automobile or hybrid vehicle is exactly Ni-MH battery or lithium ion battery.
Ni-MH battery is a kind of outstanding motive-power battery, has that power height, price are relatively low, the advantage of environmental protection, is the first-selected kind that replaces lead-acid battery and nickel-cadmium cell.
It is little that lithium ion battery has a volume, advantage such as gravimetric specific energy and gravimetric specific power height, voltage height, the feature of environmental protection are good.The energy density of lithium ion battery (volumetric specific energy and gravimetric specific energy) almost is 1.5-3 a times of nickel-cadmium cell, and under the situation of onesize energy, the volume of lithium battery and quality can reduce about 1/2.The average voltage of element cell is 3.6V, is equivalent to the magnitude of voltage that 3 NI-Gs or Ni-MH battery are connected in series.Can reduce the quantity of cell combination body, many thereby the probability of the battery failures that is caused because of the monomer battery voltage difference reduces, improved the reliability of battery pack greatly.
With respect to nickel-cadmium cell and Ni-MH battery, need not discharge earlier during lithium ion cell charging, to bringing great convenience property of use, also saved electric energy simultaneously.Lithium ion battery also possesses the low advantage of self discharge, and self-discharge rate only is 5%-10%, stores under non-working condition, and chemical reaction, quite stable take place hardly in inside.
Ni-MH battery and lithium ion battery all do not contain heavy metals such as cadmium, mercury and lead, are environment-friendly batteries.
Electric automobile generally adopts the battery pack of hundreds of volts of voltages, and this battery pack is by conduction connector cell to be combined in series-parallel mode to form.Existing interconnection technique adopts modes such as bolted, soldering, electric resistance welding, supersonic welding, Laser Welding that busbar or conducting strip are connected with cell to obtain necessary high voltages and high power capacity.
Metal commonly used connects technology and is compared as follows:
Bolted: be battery electrode column and busbar to be tightened together with bolt.
Soldering: will be called soldering than the welding that the low-melting welding material of metal fusing of mother metal (being soldered metal material) combines itself and mother metal, the welding material of metal fusing point is called solder in the welding below 450 ℃, and soldering belongs to the category of solder.Soldering technology is a kind of traditional interconnection technique, and is the same with other interconnection technique, and basic function is exactly the high reliability that will guarantee device.But tin welding spot has a great difference with other solder joint again.The scolding tin of tin soldering area can absorb and be welded the thermal deformation that substrate and device cause because of coefficient of thermal expansion differences, thereby can keep reliability.Be near the tensile strength of the scolder the eutectic point and shear strength for the highest, for tin-lead solder, tin content is 61.9% o'clock (eutectic point), 183 ℃ of fusing points.The effect of soldering can be used visual examination, and can reach components and parts deterioration etc. unusually to single welding point defect and even circuit and check simultaneously, be to adopt the most a kind of non-destructive testing method.But can't find welding internal flaws such as spaces.The visual detection method can be checked with the magnifying glass of universal projector or 10 times.
Electric resistance welding: exerts pressure by electrode in weldment combination back, and the method that the resistance heat that utilizes contact-making surface and the adjacent domain of electric current by joint to produce welds is called electric resistance welding.Electric resistance welding has the high and low cost of production efficiency, save material, be easy to characteristics such as automation, therefore is widely used in each industrial department such as Aeronautics and Astronautics, the energy, electronics, automobile, light industry, is one of important welding procedure.
Supersonic welding: the friction by material surface under the high-frequency mechanical vibration pressure produces surface molecular whirling motion and infiltration, can form permanent weld seam to the material of different melting points such as aluminum bronze iron etc., the efficient height, and quality is good, and cost is low.
Laser Welding: the principle of laser welding be the very high laser beam irradiation of energy to workpiece, make the workpiece melted by heat, cooling obtains weld seam then.Be applicable to identical or different material, the welding of the metalwork of thickness has extensive applicability, is better than conventional welding method on mechanical performance, etch resistant properties and electromagnetic property.
Said method all has application in battery industry.Said method respectively has its advantage and limitation when making power battery pack.
Bolted method advantage is simple to operate, but connects the influence that effect is subjected to fastening force, after use a period of time, can produce corrosion between the nut double-screw bolt, and electric conductivity is descended.And pole and bolt occupy no small volume, reduced the energy density of battery pack.Be only applicable to the connection of rectangle (square) batteries at present.
Soldering method soldering reliability height, easy operating, but because heating time is long, heat can be delivered on the battery, causes safety problem.Seldom directly adopt this method when making battery pack.
The material of high heat conductance and high conductivity is welded in supersonic welding easily.Materials such as gold, silver, copper, aluminium are difficult weldering in electric resistance welding, but when using ultrasonic bonding, and these metals become the different materials of the easiest welding.A major defect of metal supersonic welding is that the welding required horsepower is index with the raising of thickness of workpiece and hardness and increases severely, thereby only limits the use of in thin parts such as silk, paper tinsel, sheets.Be applied to the manufacturing of electrode and low-power battery group at present.
Laser Welding has that speed is fast, distortion is little, can weld the indissoluble material, can carry out miniature welding, be easy to advantage such as automated production; But require weldment precision height and require the position of light beam on workpiece that skew can not be arranged, the cost height of laser and related system thereof, one-time investment is big.Be applied to the manufacturing of aluminium or box hat lithium ion single battery at present.
In power type accumulator battery when work, because electric current is very big, require conduction connector to have enough current carrying capacities, in order to avoid burn or cause conduction connector heating, damage battery.In electrician's practice, the sectional area of copper aluminium and the relation of current carrying capacity are as follows:
Copper: 6A/mm
2Aluminium: 4A/mm
2,
The electric automobile starting current often reaches 200-300A, is that 500A calculates with the Safety Design, and the sectional area of copper busbar should be not less than 83mm
2, the sectional area of aluminium matter busbar should be not less than 125mm
2In the busbar of width 20mm, minimum thickness is respectively 4.15mm and 6.25mm, if width reduces, thickness can be bigger.And the thickness of the nickel matter conductive connecting piece that common low-power battery group is used only is 0.1-0.5mm.The thickness of conduction connector increases, and brings challenges for the method for attachment of conductive connecting piece and cell.
The bolted method is only applicable to the square cell, and is not suitable for the column type cell;
The soldering method will heat the thick aluminium of the thick copper of 4.15mm and 6.25mm to scolding tin fusing point (tin-lead solder, tin content is 61.9% o'clock (eutectic point), 183 ℃ of fusing points) or the fusing point of tin (231.93 ℃) required time long, excessive heat transferred will be arranged to cell top cover or bottom, for the power type accumulator battery monomer, may cause safety problem;
The electric resistance welding method is difficult weldering for good electric conducting material such as copper, aluminium usually, is difficult to directly use;
Supersonic welding only limits the use of at present in thin parts such as silk, paper tinsel, sheets, for the thick workpiece that surpasses 2mm, does not use as yet in the battery industry practice at present;
The Laser Welding method is applied in the production of metal shell storage battery (as lithium ion battery) at present, but thickness of shell is processed the intensity that thick workpiece will require to increase greatly laser usually less than 0.5mm, and the equipment needed thereby investment is huge, causes processing cost too high.
Therefore how storage battery power type accumulator battery especially when adopting thicker conduction connector, realizes effective, easy being connected of cell and conduction connector, is the big problem that is related to the battery pack reliability, also is a problem of fine solution not as yet.Reduce manufacturing cost simultaneously also is to need improved problem always.
Summary of the invention
The objective of the invention is for solving the battery cell battery and effective, easy being connected of conduction connector that above-mentioned prior art still can not fine solution, and then realize reliability and reunification cheaply.
For achieving the above object, the novel conductive connector that technical scheme of the present invention provides a kind of storage battery to use, and the storage battery that each cell is connected to form by this conduction connector.
Described conduction connector surface is covered with certain thickness tin or ashbury metal in advance, and the method that tin or ashbury metal are covered in the conduction connector surface can be physics or chemical methodes such as plating, hot-dip, sputter, vapour deposition." resistance soldering " technology with soldering technology and resistance-welding process combine by tin and the good solderability of tin alloy coat, realizes cell and effective, easy being connected of conduction connector, has reduced the storage battery manufacturing cost.
For the conduction connector Material Selection, except common high conductivity to conduction connector requires, to take into account economy simultaneously.Electric conducting material silver commonly used, aluminium, copper, nickel, iron etc. are listed in the table below with tin, plumbous physical parameter:
Metal |
Ag |
Cu |
Al |
Ni |
Fe |
Sn |
Pb |
The electricalresistivity, * 10
-8Ωm
|
1.62 |
1.72 |
2.75 |
7.24 |
9.8 |
11.4 |
21 |
[0035]
Density, g/cm
3 |
10.5 |
2.73 |
8.96 |
8.91 |
7.86 |
7.28 |
11.37 |
Fusing point, ℃ |
962 |
1083 |
660 |
1453 |
1535 |
231.9 |
327.5 |
Metal such as silver, aluminium, copper, nickel, iron or their alloy all have good conductivity, consider economy, preferred aluminium, copper, nickel, iron or its alloy.
Aluminium has excellent conducting performance, though the conductive capability of aluminium is not so good as copper, its density has only 1/3 of copper.If the material by identical weight is calculated, the twice that the conductive capability of aluminium is actually copper is many.The price of adding aluminium is cheap more than copper, and therefore in power industry, the ratio with aluminium and aluminium alloy in the lead significantly increases, and high voltage power transmission all uses aluminium and aluminium alloy to make lead on the net.The heat conductivility of aluminium might as well, industrially all do heat exchanger and radiator with aluminium.Use aluminium matter conduction connector, the manufacturing cost of battery pack will be reduced greatly, but in battery pack, seldom use at present, main cause is that aluminium is the active metal, very big with the binding energy of oxygen, the unsalted surface of aluminium can form one deck densification, nonconducting, the pellumina that can't weld immediately in air.Technical scheme of the present invention makes the aluminium surface that is easy to oxidation that protective layer arranged by being covered with metallic tin or ashbury metal, has expanded the scope of application of aluminium in battery industry.
Described " resistance soldering " technology, mean pre-aluminium conduction connector zinc-plated or that tin is plumbous is closely contacted with cell negative or positive electrode end, method with electric resistance welding is exerted pressure by electrode, utilize electric current to pass through the contact-making surface of joint and the tin or the ashbury metal on the resistance heat melting aluminum surface that adjacent domain produces, aluminium conduction connector and cell are welded together.Because the conductivity of tin or ashbury metal is significantly less than aluminium, fusing point is again much smaller than aluminium, the resistance heat I during energising
2R melts tin or ashbury metal and can not be damaged to aluminium.The advantage of this method is both to have eliminated the influence of the high heat of soldering method to cell, has solved the problem that common electric resistance welding method is difficult to welding of aluminum again.By the tin of range estimation solder joint place's fusing or the state of ashbury metal, can confirm welding effect easily simultaneously.
Certainly, because the conductivity of tin or ashbury metal is significantly less than aluminium, so tin or ashbury metal thickness that the aluminium surface is covered has certain limit, otherwise can have influence on the conductivity of connector.In order to reach enough weld strengths, the thickness of tin or ashbury metal layer can not be too little, so the thickness of tin or ashbury metal layer has an optimum range.The scope that the present invention adopts: the thickness of tin or ashbury metal layer is 1% to 50% of electric conducting material body thickness.
The shape of conduction connector can be an arbitrary shape among the present invention, as the combination of sheet, latticed, basket, wire, irregular body or above-mentioned different shape, and preferred sheet.Can be provided with semicircle punching on the conduction connector, be complementary with the both positive and negative polarity of cell.Battery cell connects in the soldering mode by conduction connector, and conduction connector itself can be independent or continuous sheet metal.
Manufacture method of the present invention also is applicable to copper or other conductive connecting materials.The conductivity of copper is superior to almost each metal, is only second to silver, is used for electrical industry in a large number.Copper is the good surface of soldered elements, but oxidation easily; The copper of any exposure is all with the nonweldable cupric oxide of very fast formation.Be covered with metallic tin or ashbury metal and make the copper surface that is easy to oxidation that protective layer arranged, increased the scope of application of copper.Though nickel and iron are electric resistance welding materials commonly used, when doing the connection material of battery pack,, have any problem because the problem of thickness is thought direct electric resistance welding and don't damage battery.Be covered with metallic tin or ashbury metal, adopt " resistance soldering " of the present invention technology, solved the problems referred to above well.
Conduction connector among the present invention can also be made by any material combination of aluminium, copper, iron, nickel or its alloy.And this conduction connector with the both positive and negative polarity connection of each cell, also can be provided with the aluminium different, copper, iron, nickel nail, because the good characteristic of copper in welding procedure, preferably fastener with the body material.
Beneficial effect of the present invention is:
1. the aluminium matter conduction connector of pre-coated tin involved in the present invention or ashbury metal, make the application of aluminium in the conduction connector of storage battery become possibility, electric conducting materials such as the copper comparison with traditional had both reduced material cost, alleviate material weight again, helped improving the gravimetric specific energy of battery pack.
2. storage battery involved in the present invention, the conduction connector of the materials such as aluminium of tin or ashbury metal is covered in utilization in advance, adopts " resistance soldering " technology that each cell is fitted together, and it is easy, easy to implement, low cost of manufacture.
3. storage battery involved in the present invention, its welding effect can have been saved the detection cost by visual inspection.
Description of drawings
Fig. 1 is the sheet conduction connector among the present invention.
Fig. 2 is first the circular punching schematic diagram of conduction connector among the present invention.
Fig. 3 is the 3.6V/44Ah storage battery assembling schematic diagram that is made of 20 cylindrical lithium ion battery monomers.
Fig. 4 is the 10.8V/60Ah storage battery assembling schematic diagram that is made of 60 cylindrical lithium ion battery monomers.
Embodiment
Further specify the present invention below in conjunction with drawings and Examples, but not as a limitation of the invention.
Embodiment one is with 20 capacity 2200mAh, diameter is about 18mm, the lithium ion battery that highly is about 65mm is a monomer, be combined into 3.6V/44Ah lithium ion battery group by the sheet conduction connector shown in the accompanying drawing 1 in the mode of accompanying drawing 3, conduction connector covers the aluminum or aluminum alloy plate of tin in this example for the surface.
By on aluminium sheet, going out semicircular hole, directly form the lug (as shown in Figure 2) of semicircle shape, each battery on the position that designs with aluminium sheet on the lug of semicircle shape weld together with the mode of resistance soldering, each cell directly links to each other by 19 monomers of brace and other in the accompanying drawing 3.Welding condition is: 6 kilowatts of welder powers, and electric current 20-30 ampere, voltage 50-200 volt is to reduce the influence of heat to battery cell at time 0.5-4 second, adopts the short time as far as possible.
Welding effect is by the tin thickness on aluminium sheet decision, following table welding effect when covering the tin layer of different-thickness on the different-thickness aluminium sheet.
|
Sn=0.01mm |
Sn=0.02mm |
Sn=0.04mm |
Sn=0.06mm |
Sn=0.08mm |
Al=0.2mm |
Good |
Good |
Good |
Good |
Good |
Al=0.4mm |
Can accept |
Good |
Good |
Good |
Good |
Al=0.8mm |
Difference |
Can accept |
Good |
Good |
Good |
Al=1.2mm |
Difference |
Difference |
Good |
Good |
Good |
[0056]
A1=1.6mm |
Difference |
Difference |
Can accept |
Good |
Good |
From last table, can find out, when aluminium plate thickness 0.4mm, as long as 2.5% tin layer can reach the welding effect that needs.Tin bed thickness in general, good connecting effect, but because therefore the conductivity of tin poor than aluminium also will control tin thickness.
Embodiment two is with 20 capacity 2200mAh, diameter is about 18mm, to be monomer be combined into 3.6V/44Ah lithium ion battery group by the conduction connector shown in the accompanying drawing 1 in the mode of accompanying drawing 3 to the lithium ion battery that highly is about 65mm, and brace covers the aluminium sheet of tin/lead alloy in this example for the surface.The result shows that the aluminium sheet that covers tin/lead alloy has identical effect with the aluminium sheet that covers tin.
Embodiment three is a battery pack similarly to Example 2, but conductive connecting piece is the surperficial copper coin that covers tin/lead alloy in this example.The result shows that copper coin and aluminium sheet have identical effect.
Embodiment four is a battery pack similarly to Example 2.In the present embodiment, conduction connector is the aluminum or aluminum alloy plate, is provided with the tingle of bronze medal or copper alloy on this conduction connector and each cell junction, and tin is covered on the conduction connector surface.
Embodiment five is with 20 capacity 3.0Ah, diameter is about 26mm, the lithium ion battery that highly is about 70mm is a monomer, be combined into 3.6V/60Ah lithium ion battery group by the conduction connector shown in the accompanying drawing 1, become 10.8V/60Ah lithium ion battery group with three above-mentioned battery combination by the mode tandem compound of accompanying drawing 4 again, brace covers the aluminium sheet of tin for the surface in this example, and can link together by soldering, welding or riveted way between the conductive connecting piece.
The foregoing description one to five, employing be lithium-ion battery monomer, but storage battery manufacture method of the present invention is not limited in lithium ion battery, Ni-MH battery or other storage batterys adopt this method can obtain effect of the present invention equally.From the practical application angle, small-sized cylindrical battery monomer (as diameter less than 40mm) adopts the effect of the present invention can be better.