CN103904368A - Lithium secondary battery - Google Patents

Abstract

The present invetion provides a lithium secondary battery that renders safe and excellent performance at a high temprature. The lithium secondary battery is formed by when a flatly wound electrode body and non aqueous electrolyte are sealed in a center hollowed battery box with a width of 40mm. The flatly wound electrode body is provided with a position wire guiding body and a negative wire guiding body and are spaced by filmes so that the wire guiding bodies protrude in the same direction. The diaphragm has a porous layer with a thermoplastic resin as the main body (I) and containing heat-resistant temperature is above 150 DEG C packed porous layer as the main body (II). The thickness of the porous layer (II) is less than 8 mum. The flatly wound electrode body, positive lead and a negative lead body highlights the end and are opposite to each other. The substrate contains non-melting resin at a closed temprature.

Description

Lithium secondary battery

Technical field

The present invention relates to the lithium secondary battery of excellent in safety.

Background technology

In recent years, be accompanied by development, electric automobile practical etc. of the portable electric appts such as mobile phone, subnotebook PC, seeking to can be used as secondary cell, the further high performance of capacitor, high stability that their power supply uses.Especially lithium secondary battery gets most of the attention as the high battery of energy density, is advancing various improvement as the applicable power supply of aforementioned device class.

With regard to the lithium secondary battery that particularly can be used for significantly smart mobile phone, flat board etc. with regard to performance gains, the screen size of equipment is larger than mobile phone, battery size also maximizes along with the size of equipment, thereby has realized high power capacity.Such lithium secondary battery is to form like this: at the battery case being formed by aluminium or its alloy and be disposed in the confined space that the lid of the openend of battery case forms, hold electrodes body (rolled electrode body) and nonaqueous electrolytic solution, electrode body (rolled electrode body) is stacked and reel and form across barrier film for the lead-in wire positive pole of body and negative pole are installed.

In lithium secondary battery, be accompanied by the requirement of high capacity, also in the raising of seeking reliability, fail safe.For example, in patent documentation 1, the technology that the specific place of rolled electrode body of making flat is fixed with adhesive tape is disclosed for the durability of lithium secondary battery to impacts such as falling, the reliability in repeated charge are improved.

In addition, about the fail safe of lithium secondary battery, thereby proposed for example to make barrier film shrink the various technology of the anodal problem directly contacting with negative pole for avoiding owing to becoming excessive high temperature in battery.

For example, in patent documentation 2, to disclose in order suppressing and, because the temperature rise of battery case makes to shrink at the part barrier film contacting with battery case of rolled electrode body, to have arranged the technology of the insulating component that high-temperature capability is higher than barrier film in this part.In addition in patent documentation 3, the technology that the outstanding part of the each electrode from rolled electrode body of the barrier film that forms rolled electrode body is engaged each other is integratedly disclosed.

Further, in patent documentation 4, the technology that forms barrier film with the 1st membrane layer and the 2nd membrane layer is disclosed, the 1st membrane layer is containing being useful on the thermoplastic resin etc. of guaranteeing closing function, and the 2nd membrane layer has by containing stable on heating filler the function that high-fire resistance, performance suppress the thermal contraction of barrier film entirety.

Prior art document

Patent documentation

Patent documentation 1: TOHKEMY 2007-172975 communique

Patent documentation 2: TOHKEMY 2000-251866 communique

Patent documentation 3: TOHKEMY 2004-327362 communique

Patent documentation 4: Japan internationality discloses No. 2007/066768

Summary of the invention

Invent problem to be solved

For example, if the barrier film that patent documentation 4 is recorded, just can improve well fail safe, the reliability of lithium secondary battery.

But, for lithium secondary battery, also pursued the high power capacity increasing in the past, if for example by making barrier film thin and make positive pole, negative pole thick, the active matter quality that makes to be directed into the both positive and negative polarity in battery improves, thereby realize high capacity, the thermal endurance of barrier film becomes insufficient, the worry that exists the fail safe under excessive high temperature to reduce.And about the reduction of such fail safe, the size of battery case is more worrying.

For this reason, even if need to develop the high capacity of realizing lithium secondary battery by foregoing method, also can guarantee the technology of good fail safe.

The present invention makes in view of afore-mentioned, its objective is the lithium secondary battery that a kind of excellent in safety under high temperature is extremely provided.

For solving the method for problem

The feature that can reach the lithium secondary battery of the present invention of aforementioned object is, it is enclosed the lithium secondary battery that the battery case of hollow columnar forms for flat rolled electrode body and nonaqueous electrolytic solution, and described flat rolled electrode body is the negative pole that has the positive pole of positive wire body and have a negative wire body across barrier film and overlapping and be wound into helical form and form to the outstanding mode of equidirectional with aforementioned positive wire body and aforementioned negative wire body; Aforementioned barrier film has the porous layer (I) using thermoplastic resin as main body and contains the porous layer (II) of heat resisting temperature as more than 150 ℃ fillers as main body, and the thickness of aforementioned porous layer (II) is below 8 μ m; In aforementioned flat rolled electrode body, the end face that aforementioned positive wire body and aforementioned negative wire body have been given prominence to and relative to each other and width 2 sides wider than other faces adhesive tape with base material be fixed, the resin that described base material contains the not melting of temperature below closing temperature (Shut Down Temperature), the width of aforementioned battery case is more than 40mm.

In this specification, " heat resisting temperature is more than 150 ℃ " meaning is at least in the time of 150 ℃, not find softening grade for distortion.

Invention effect

According to the present invention, can be provided in the lithium secondary battery of the excellent in safety under high temperature extremely.

Accompanying drawing explanation

Fig. 1 be pattern represent the stereogram of an example of the flat rolled electrode body that lithium secondary battery of the present invention relates to;

Fig. 2 be pattern represent other routine stereograms of the flat rolled electrode body that lithium secondary battery of the present invention relates to;

Fig. 3 be pattern represent other routine stereograms of the flat rolled electrode body that lithium secondary battery of the present invention relates to;

Fig. 4 be pattern represent the stereogram of an example of lithium secondary battery of the present invention;

Fig. 5 be pattern represent the part sectional arrangement drawing of an example of lithium secondary battery of the present invention.

Symbol description

1-lithium secondary battery; 10-battery case; 11-outer packing shell; Wide of 111-battery case (outer packing shell) lateral parts; The 12-ditch that ftractures; 20-lid; 30-flat rolled electrode body; 51-positive wire body; 52-negative wire body; 60-adhesive tape.

Embodiment

In lithium secondary battery of the present invention, for the barrier film between positive pole and negative pole, use the barrier film that there is the porous layer (I) using thermoplastic resin as main body and contain the porous layer (II) of heat resisting temperature as more than 150 ℃ fillers as main body.

The porous layer (I) that barrier film relates to is mainly used in guaranteeing closing function, in the time that lithium secondary battery reaches above as the fusing point of thermoplastic resin of composition of main body that becomes porous layer (I), the thermoplastic resin melting that porous layer (I) relates to, thereby stop up the emptying aperture of barrier film, the closing of carrying out of electrochemical reaction occurs to suppress.

In addition, the porous layer (II) that barrier film relates to, even if also possess the direct function that contacts the short circuit causing preventing by positive pole and negative pole in the time that the internal temperature of lithium secondary battery rises, is that 150 ℃ of above fillers have been guaranteed this function by heat resisting temperature.,, in the situation that battery becomes high temperature, even if for example porous layer (I) shrinks, also can, by the porous layer (II) that is difficult to shrink, prevent the contingent short circuit being caused by the direct contact of both positive and negative polarity in the situation that of barrier film thermal contraction.In addition,, because the porous layer (II) of this excellent heat resistance plays a role as the skeleton of barrier film, can also suppress the thermal contraction of porous layer (I), the i.e. thermal contraction itself of barrier film entirety.

Here, about the barrier film the present invention relates to, for example, for the high capacity of lithium secondary battery, make below thin thickness to the 8 μ m of porous layer (II), thereby suppress the increase of the thickness of barrier film entirety, compared with the barrier film that the micro-porous film by polyolefin system using with common lithium secondary battery forms, can guarantee excellent thermal endurance.

; having in the lithium rechargeable battery of flat rolled electrode body; this flat rolled electrode body is the negative pole that has the positive pole of positive wire body and have a negative wire body across barrier film and overlapping and be wound into helical form and form to the outstanding mode of equidirectional with positive wire body and negative wire body; if in this lithium rechargeable battery be held in the condition of high temperature time inside heat distribution resolve, distinguish and become the region of high temperature more centered by positive wire body and negative wire body and distribute.

But also distinguish, make to bring into play the barrier film that stable on heating porous layer (II) is thin in use, when in battery, excessive temperature rises, especially near the part being disposed in the lead-in wire body of the both positive and negative polarity that becomes high temperature, the inhibitory action of thermal contraction is insufficient, exists the anodal worry contacting with negative pole occurs.

As previously mentioned, there is the demand that lithium secondary battery is maximized, especially the width of battery case being made as to 40mm when above, than compared with its little battery, make the width of lead-in wire body of the both positive and negative polarity that flat rolled electrode body relates to large, in this case with battery case width more, even if the percent thermal shrinkage of barrier film is identical, the area that shrinks generation area is that amount of contraction also increases, and therefore, the anodal problem contacting with negative pole becomes more easily and occurs.

In Fig. 1, show pattern and represented the stereogram of an example of the flat rolled electrode body that lithium secondary battery of the present invention relates to.In rolled electrode body 30 shown in Fig. 1, the end face 302 that positive wire body 51 and negative wire body 52 have been given prominence to and the side of front side and the side of rear side relative to each other and in width 2 sides 301 than other faces wider, 301(figure) fixed by adhesive tape 60.

As shown in Figure 1, in lithium secondary battery of the present invention, the end face that positive wire body and negative wire body in flat rolled electrode body have been given prominence to and relative to each other and width 2 sides wider than other faces be fixed by adhesive tape.And, for aforementioned adhesive tape, use the adhesive tape using the resin of the not melting of temperature below the closing temperature of lithium secondary battery as base material.

In flat rolled electrode body, in order to prevent that anodal and negative pole from, the contacting of its end face (upper surface shown in Fig. 1 and lower surface), configuring with its end barrier film from positive pole, the outstanding mode of negative pole.By by owing to having positive wire body, negative wire body and worrying that especially end face and 2 wider side high adhesive tapes of thermal endurance of width of the flat rolled electrode body of the thermal contraction of barrier film are fixed, can make the partial fixing outstanding from the aforementioned end face of barrier film, therefore, even excessive temperature rises in battery, also can highly suppress the thermal contraction of the barrier film in this region.

In lithium secondary battery of the present invention, by adopting aforementioned structure, even in the case of being made as foregoing, can be made as high power capacity more structure, also can guarantee the high security under high temperature.

Here, in this specification, the closing temperature of said lithium secondary battery is the value that the method that adopts by aftermentioned embodiment is measured.

Below embodiments of the present invention are at length described, but they are only examples of embodiments of the present invention, the present invention is not limited to their content.

< barrier film >

As previously mentioned, the barrier film the present invention relates to has the porous layer (I) using thermoplastic resin as main body and contains the porous layer (II) of heat resisting temperature as more than 150 ℃ fillers as main body.

As the thermoplastic resin of main body that becomes porous layer (I), preferably fusing point, the melting temperature measured according to differential scanning calorimeter regulation for (DSC) of JIS K 7121 is 140 ℃ of resins below, particularly, can enumerate for example polyethylene (PE).As the form of porous layer (I), can be set forth in dispersion liquid that on the base material such as micro-porous film, nonwoven fabrics that conventionally can be used as secondary lithium batteries barrier film, coating contains PE particle tablet dry etc. and the material that obtains etc.In addition, also can use have the layer that formed by PE with formed by polypropylene (PP) layer the micro-porous film of multilayer (2 layers, 3 layers etc.) structure as porous layer (I).

In the cumulative volume of the constituent of porous layer (I), (remove the cumulative volume after emptying aperture part.The volume containing ratio of the porous layer (I) relating to about barrier film and the constituent of porous layer (II), lower same.), the volume containing ratio that becomes the thermoplastic resin of main body is more than 50 volume %, more preferably more than 70 volume %.Here, for example the former micro-porous film of stating PE forms in the situation of porous layer (I), and the volume containing ratio of thermoplastic resin is 100 volume %.

The filler relating to about porous layer (II), the material of the electrochemical stability of oxidized reduction is stablized, further in the operating voltage range of battery, is difficult to nonaqueous electrolytic solution above for 150 ℃ as long as heat resisting temperature and that have for battery, be that inorganic particulate, organic filler all can, from viewpoints such as dispersions, be preferably particulate, in addition, preferably inorganic oxide particle, more specifically, preferential oxidation aluminium, silicon dioxide, boehmite.Because aluminium oxide, silicon dioxide, boehmite oxidative resistance are high, can be by particle diameter, Adjusting Shape to desired numerical value etc., so easily with the void content of good accuracy control porous layer (II).Here, be 150 ℃ of above fillers about heat resisting temperature, for example, can use separately a kind of aforementioned illustrative material, also two or more kinds may be used.

The heat resisting temperature relating to about porous layer (II) is that the shape of 150 ℃ of above fillers is not particularly limited, and can use roughly spherical (comprising just spherical), the filler of ellipsoid shaped (comprising ellipsoid shaped), the various shapes such as tabular roughly.

In addition, too small if the heat resisting temperature that porous layer (II) relates to is the average grain diameter of 150 ℃ of above fillers, the permeability of ion reduces, therefore, and more than being preferably 0.3 μ m, more preferably more than 0.5 μ m.In addition, if heat resisting temperature is that 150 ℃ of above fillers are excessive, electrical characteristics become easily deteriorated, and therefore, its average grain diameter is preferably below 5 μ m, more preferably below 2 μ m.

The average grain diameter of the said various particles of this specification (heat resisting temperature is 150 ℃ of above filler, lithium-contained composite oxides described later etc.) is for example to use Laser Scattering Particle Size Distribution Analyzer (for example, hole field makes made " LA-920 ") in the undissolved medium of particle, to make these particles disperse and the average grain diameter D of mensuration _50%.

Porous layer (II) is that to contain heat resisting temperature be the materials of 150 ℃ of above fillers as main body, and therefore, heat resisting temperature is that 150 ℃ of above fillers (are removed the cumulative volume after emptying aperture part at the cumulative volume of the constituent of porous layer (II).About the cumulative volume of the constituent of porous layer (II) and porous layer (I), lower with.) in volume containing ratio be more than 50 volume %, more than being preferably 70 volume %, more preferably more than 80 volume %, more preferably more than 90 volume %.By the aforementioned filler in porous layer (II) is made as to foregoing high containing ratio, even in the time that lithium secondary battery becomes high temperature, also can suppress well the thermal contraction of barrier film entirety, can suppress more well by the direct generation that contacts the short circuit causing anodal and negative pole.

Here, as described later, because preferably also contain organic bond in porous layer (II), therefore heat resisting temperature is that the volume containing ratio of 150 ℃ of above fillers in the cumulative volume of the constituent of porous layer (II) is preferably below 99.5 volume %.

In porous layer (II), in order to make, heat resisting temperature is that 150 ℃ of above fillers are bonded to one another, porous layer (II) and porous layer (I) integrated etc., preferably contain organic bond.As organic bond, can enumerate ethylene-vinyl acetate copolymer (EVA, be the copolymer of 20～35 % by mole from the construction unit of vinylacetate), ethylene-acrylic acid copolymer, the fluorine such as ethylene-ethyl acrylate copolymer be rubber, SBR, CMC, hydroxyethylcellulose (HEC), polyvinyl alcohol (PVA), polyvinyl butyral resin (PVB), polyvinylpyrrolidone (PVP), crosslinked acrylic resin, polyurethane, epoxy resin etc., particularly preferably uses the stable on heating adhesive with 150 ℃ of above heat resisting temperatures.Organic bond can use separately a kind of aforementioned illustrative material, and also two or more kinds may be used.

Among aforementioned illustrative organic bond, preferably EVA, ethylene-acrylic acid copolymer, fluorine are the adhesive that the flexibility such as rubber, SBR is high.As the object lesson of the high organic bond of such flexibility, there is " TRD-2001(SBR) " of " DAI-EL LATEX series (fluorubber) ", the JSR society of EEA, the Daikin Industries society of " the EVA FLEX-EEA series (ethylene-acrylic acid copolymer) " of EVA, the polymeric chemical society of Mitsui Du Pont of " the EVA FLEX series (EVA) " of polymeric chemical society of Mitsui Du Pont, Japanese You Nika society, Japanese You Nika society, Japanese Rui Weng society " BM-400B(SBR) " etc.

Here, by aforementioned organic bond for the porous layer (II) in the situation that, can use with the form that forms the latex dissolving in the solvent of composition of use or disperse at porous layer described later (II).

Barrier film for example can be manufactured by following method: be that the porous layer (II) of 150 ℃ of above fillers etc. forms the surface that is coated on the tablets such as micro-porous film for forming porous layer (I) with composition liquid compositions such as (etc.) slips by containing heat resisting temperature, dry at the temperature of regulation, thus porous layer (II) formed.

It is to contain heat resisting temperature to be 150 ℃ of above fillers, to contain organic bond etc. and they are scattered in to solvent and (comprise decentralized medium as required that porous layer (II) forms with composition.Lower same.) composition.Here, about organic bond, also can be dissolved in solvent.Porous layer (II) form with the operable solvent of composition as long as can make heat resisting temperature be 150 ℃ of uniform filling above the solvent that disperses and can make organic bond dissolve equably or disperse, can use aptly the general organic solvents such as ketone such as the furans such as aromatic hydrocarbon, oxolane, methyl ethyl ketone, methyl iso-butyl ketone (MIBK) such as such as toluene.Here,, take control surface tension force as object, in these solvents, can suitably add the various expoxy propane such as alcohol (ethylene glycol, propylene glycol etc.) or monomethyl acetic acid esters is glycol ethers etc.In addition, at organic bond be in water miscible situation, inferior in situation about using as latex, can be using water as solvent, now also can suitably add alcohols (methyl alcohol, ethanol, isopropyl alcohol, ethylene glycol etc.) and carry out control surface tension force.

About porous layer (II) formation composition, preferably will comprise that heat resisting temperature is that the solid component content of 150 ℃ of above filler, organic bonds etc. is made as for example 10～80 quality %.

In barrier film, it is respectively 1 layer separately that porous layer (I) and porous layer (II) there is no need, and also can have multiple layers in barrier film.For example, can be made as on the two sides of porous layer (II) and dispose the structure of porous layer (I), or be made as the structure that disposes porous layer (II) on the two sides of porous layer (I).But, thereby there is the worry that causes the reduction of increase, the energy density of the internal resistance of battery due to the thickness that increases the number of plies and increase barrier film, thereby preferably do not make the number of plies too much, porous layer (I) in barrier film and the total number of plies of porous layer (II) are preferably below 5 layers, are particularly preferably 2 layers.

The thermal endurance of the thicker barrier film of porous layer (II) in barrier film more improves, if but blocked up, barrier film entirety thickening, thus for example unfavorable for the high capacity of realizing lithium secondary battery.Therefore, the thickness of porous layer (II) (is its gross thickness in the situation that barrier film has multiple porous layers (II).Lower same.) be below 8 μ m, more preferably below 6 μ m.But, if porous layer (II) is excessively thin, exist the thermal endurance of the barrier film being produced by forming of porous layer (II) to improve the worry that effect diminishes.Therefore, more than the thickness of porous layer (II) is preferably 0.5 μ m, more preferably more than 2 μ m.

In addition (in the situation that barrier film has multiple porous layers (I), be its gross thickness about the thickness of the porous layer in barrier film (I).Lower same.), from more effectively bringing into play the viewpoint of the aforementioned effect (particularly closing function) being produced by the use of porous layer (I), more than being preferably 5 μ m, more preferably more than 10 μ m.But, if (I) is blocked up for porous layer, except existing as previously mentioned porous layer (II) thus the worry that diminishes of the effect that increases of the thickness thickness that causes restriction to make to suppress barrier film entirety, the worry that the effect that also exist the power that makes porous layer (I) thermal contraction to become large, to suppress the thermal contraction of barrier film entirety diminishes.Therefore, the thickness of porous layer (I) is preferably below 20 μ m, more preferably below 16 μ m.

And about the thickness of barrier film entirety, the viewpoint of the effect producing from the thickness of guaranteeing more well by limiting as previously mentioned porous layer (II), is preferably below 28 μ m, more preferably below 21 μ m.But, if every lepthymenia, there is the worry of undercapacity, thereby more than its overall thickness is preferably 10 μ m.

As the void content of barrier film entirety, in order to ensure guarantor's liquid measure of nonaqueous electrolytic solution, make ion permeability good, under dry state, be preferably more than 30%.On the other hand, from guaranteeing barrier film intensity and the viewpoint that prevents internal short-circuit, the void content of barrier film is preferably below 70% under dry state.Here the void content of barrier film: P(%) can obtain about the summation of each component i and calculate by following (1) formula by the density of the quality of the thickness from barrier film, unit are, constituent.

P＝｛1-（m/t）/（Σa _i·ρ _i）｝×100 （1）

Here, in aforementioned formula, a _ifor the ratio using overall quality as 1 o'clock component i, ρ _ifor the density (g/cm of component i ³), m is the quality (g/cm of barrier film per unit area ²), the thickness (cm) that t is barrier film.

In addition, in aforementioned (1) formula, also can be by m being made as to the quality (g/cm of porous layer (I) per unit area ²), by t be made as the thickness (cm) of porous layer (I), by a _ibe made as at the ratio using quality overall porous layer (I) as 1 o'clock component i, obtain the void content of porous layer (I): P(% by aforementioned (1) formula).The void content of the porous layer (I) of obtaining by the method is preferably 30～70%.

Further, in aforementioned (1) formula, can also be by m being made as to the quality (g/cm of porous layer (II) per unit area ²), by t be made as the thickness (cm) of porous layer (II), by a _ibe made as at the ratio using quality overall porous layer (II) as 1 o'clock component i, obtain the void content of porous layer (II): P(% by aforementioned (1) formula).The void content of the porous layer (II) of obtaining by the method is preferably 20～60%.

As barrier film, the barrier film that preferred mechanical intensity is high, for example, more than puncture intensity is preferably 3N.For example, the large SiO of change in volume discharging and recharging will followed _xfor (being described in detail later) in the situation of negative electrode active material, by repeatedly discharging and recharging, due to the flexible of negative pole entirety for causing mechanical damage at the barrier film of facing.If the puncture intensity of barrier film is more than 3N, can guarantees good mechanical strength, relax the suffered mechanical damage of barrier film.By barrier film being made to previously illustrated structure, can make its puncture intensity is aforementioned value.

Aforementioned puncture intensity can be measured by following method.On the plate in hole that has 2 inches diameter, barrier film is fixed in the mode that there is no fold, deflection, making point diameter is that the spherical metal needle of the semicircle of 1.0mm drops to and measures on sample with the speed of 120mm/min, measures the power while producing hole on 5 barrier films.And, obtain mean value for maximum and minimum value being removed to 3 times later mensuration among aforementioned 5 measured values, set it as the puncture intensity of barrier film.

The anodal > of <

In the positive pole relating at lithium secondary battery of the present invention, can use the electrode for example with following structure: there is the anode mixture layer containing positive active material, adhesive and conductive auxiliary agent etc. in the one or two sides of collector body.

< positive active material >

The positive active material relating to for lithium secondary battery of the present invention, uses the lithium-contained composite oxide that for example contains lithium (Li) and transition metal.

As the object lesson of the lithium-contained composite oxide that contains Li and transition metal, can enumerate for example LiCoO ₂deng lithium and cobalt oxides, LiMnO ₂, Li ₂mnO ₃deng lithium manganese oxide, LiNiO ₂deng lithium nickel oxide, LiMn ₂o ₄, Li _4/3ti _5/3o ₄deng the lithium-contained composite oxide of spinel structure, LiFePO ₄deng the lithium-contained composite oxide of olivine structural, the oxide replacing take aforesaid oxides as basic composition and by various elements etc.

Here, at least a portion that positive active material is preferably the lithium-contained composite oxide that contains lithium and transition metal is to contain the lithium-contained composite oxide of Ni as transition metal, and the molar ratio of total Ni amount is more than 0.05 below 1.0 with respect to the total Li amount in whole positive active materials.

What is called contains the lithium-contained composite oxide of Ni as transition metal, refer to and at least contain the lithium-contained composite oxide of Ni as the transition metal of the aforementioned composite oxides of formation, can contain Co, Mn, titanium (Ti), chromium (Cr), iron (Fe), copper (Cu), silver (Ag), thallium (Ta), niobium (Nb), other transition metal such as zirconium (Zr) are as component, in addition, can also contain for example boron (B), phosphorus (P), zinc (Zn), aluminium (Al), calcium (Ca), strontium (Sr), barium (Ba), germanium (Ge), tin (Sn), element beyond the transition metals such as magnesium (Mg).

Because contain Ni as the lithium-contained composite oxide of transition metal at 3～4.4V(to Li) near Capacity Ratio LiCoO ₂large Deng other lithium-contained composite oxides, so favourable to the high capacity of lithium secondary battery.So, from realizing the viewpoint of high capacity of lithium secondary battery, preferably, with respect to the total Li amount in whole positive active materials, the molar ratio of total Ni amount is made as more than 0.05.

But, on the other hand, contain Ni high as the lithium-contained composite oxide of transition metal and the reactivity of nonaqueous electrolytic solution.Therefore, with regard to using contain Ni as the lithium-contained composite oxide of transition metal as the lithium secondary battery of positive active material with regard to, under the state of charging, be placed in excessive high temperature when inferior, battery temperature can further rise, and has the worry that produces thermal runaway etc.Especially using contain Ni as the lithium-contained composite oxide of transition metal in the lithium secondary battery of positive active material, by with than using LiCoO ₂battery more improve at the final voltage in when charging and use, can expect to realize the further high capacity of battery, but charge under more high-tension state, the danger of aforementioned hot grade out of control more can increase.In lithium secondary battery of the present invention, have the aforementioned barrier film of porous layer (I) and porous layer (II) except using, also use the specific place of specific adhesive tape fixing wound electrode body, so, even realize high capacity by preceding method, also can guarantee high fail safe.

Lithium secondary battery of the present invention with for example with LiCoO ₂lithium secondary battery in the past as positive active material is same, go for carrying out final voltage being made as to the purposes that determining about 4.2V uses after electric current-constant-voltage charge, in the case of using contain Ni as the lithium-contained composite oxide of transition metal for positive active material, from realizing the more viewpoint of high capacity, more preferably be applicable to have carried out to make final voltage to exceed the purposes that uses after electric current-constant-voltage charge of determining of 4.30V, under state after the condition charging with such, even if it is inferior to be placed in excessive hot environment, fail safe is also good.

Containing in the lithium-contained composite oxide of Ni as transition metal, the viewpoint that stability from thermal stability, high potential state is high, the fail safe that can make lithium secondary battery, various battery behavior improve more, is preferably used the represented lithium-contained composite oxide of following composition general formula (2).

Li _1＋yMO ₂ （2）

(in aforementioned component general formula (2),-0.15≤y≤0.15, and M represents at least to comprise 3 kinds of above element set of Ni, Co and Mn, in each element of composition M, in the time that the ratio of Ni, Co and Mn (mol%) is made as respectively to a, b and c, 25≤a≤90,5≤b≤35,5≤c≤35 and 10≤b+c≤70.〕

Here, represent that the element set M in the aforementioned component general formula (2) of aforementioned lithium-contained composite oxide can only contain Ni, Co and Mn, but the element containing beyond Ni, Co and Mn also has no relations, the elements such as such as Ti, Cr, Fe, Cu, Zn, Al, Ge, Sn, Mg, Ag, Ta, Nb, B, P, Zr, Ca, Sr, Ba.But, in aforementioned lithium-contained composite oxide, in order fully to obtain the aforementioned effect producing by containing Ni, Co and Mn, when whole first prime number of element set M is made as to 100mol%, the total ratio (mol%) of the element beyond Ni, Co and Mn is preferably below 15mol%, more preferably below 3mol%.

The lithium-contained composite oxide with aforementioned component becomes its real density for height is to 4.55～4.95g/cm ³value, there is the material of high volume energy density.Here, the real density of the lithium-contained composite oxide that contains Mn with certain limit significantly changes according to the difference of its composition, but stabilized in aforementioned narrow like that compositing range inner structure, can improve uniformity, therefore, can think to become for example to approach LiCoO ₂the large value of real density.In addition, can make the capacity of unit mass of lithium-contained composite oxide large, can make the material of invertibity excellence.

Here, when in positive active material, with respect to the total Li amount in whole positive active materials, by the molar ratio of total Ni amount while being adjusted to more than 0.05 below 1.0, can only use and contain the lithium-contained composite oxide of Ni as transition metal, can also when use contains the lithium-contained composite oxide of Ni as transition metal, use other lithium-contained composite oxides (aforesaid LiCoO ₂deng lithium and cobalt oxides, LiMnO ₂, Li ₂mnO ₃deng lithium manganese oxide, LiMn ₂o ₄, Li _4/3ti _5/3o ₄deng the lithium-contained composite oxide of spinel structure, LiFePO ₄deng the lithium-contained composite oxide of olivine structural, the oxide replacing take aforesaid oxides as basic composition and with various elements etc.).In this case, will contain Ni as the one kind or two or more of one kind or two or more and other otide containing lighium things of the lithium-contained composite oxide of transition metal and with also having no relations.

More than the average grain diameter of lithium-contained composite oxide used in the present invention is preferably 5 μ m, more preferably more than 10 μ m, in addition, be preferably below 25 μ m, more preferably below 20 μ m.Here, the particle of these lithium-contained composite oxides can be to condense by primary particle the secondary aggregation body forming, and the average grain diameter meaning of this situation is the average grain diameter of secondary aggregation body.

Further, about lithium-contained composite oxide used in the present invention, from guaranteeing the reasons such as the side reaction with reactivity, inhibition and the nonaqueous electrolytic solution of lithium ion, the specific area being obtained by BET method is preferably 0.1～0.4m ²/ g.The specific area being obtained by BET method of lithium-contained composite oxide can be used utilizes the specific area measuring device (Mountech society system " Macsorb HM modele-1201 ") of nitrogen adsorption method to measure.

The containing ratio of positive active material in anode mixture layer (all total containing ratios of positive active material) is preferably 60～95 quality %.

The conductive auxiliary agent > of < anode mixture layer

The conductive auxiliary agent of the anode mixture layer that the positive pole of lithium secondary battery of the present invention relates to is as long as chemically stable material in lithium secondary battery.Can enumerate the graphite such as such as native graphite (flaky graphite etc.), Delanium, the carbon blacks such as acetylene black, Ketjen black (trade name), channel carbon black, oven process carbon black, dim, thermal black, the conducting fibre such as carbon fiber, metallic fiber, the metal dusts such as aluminium powder, fluorocarbons, zinc oxide, the conductivity whisker being formed by potassium titanate etc., the conductive metal oxides such as titanium oxide, the organic conductive materials such as polyphenylene derivative etc., they can be used alone or two or more kinds may be used.Wherein, the graphite that preferably conductivity is high, the carbon black of absorbency excellence.In addition, as the form of conductive auxiliary agent, be not limited to primary particle, can also use the material of the aggregate forms such as secondary aggregation body, chain structure.Such aggregate processing ease, productivity ratio is good.

The containing ratio of the conductive auxiliary agent in anode mixture layer is preferably 3～20 quality %.

The adhesive > of < anode mixture layer

The adhesive of the anode mixture layer that the positive pole of lithium secondary battery of the present invention relates to, as long as chemically stable adhesive in lithium secondary battery, can use any kind in thermoplastic resin, thermosetting resin.More specifically, can enumerate for example polyethylene, polypropylene, the vinylidene based polymers (VDF based polymer) take vinylidene (VDF) as main component monomer such as Kynoar (PVDF), polytetrafluoroethylene (PTFE), polyhexafluoropropylene (PHFP), butadiene-styrene rubber, tetrafluoroethylene-vinylidene fluoride copolymer (P(TFE-VDF)), tetrafluoroethene-hexafluoroethylene copolymer, tetrafluoraoethylene-hexafluoropropylene copolymer (FEP), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), ethylene-tetrafluoroethylene copolymer (ETFE), polychlorotrifluoroethylene (PCTFE), propylene-TFE copolymer, ethylene-chlorotrifluoro-ethylene copolymer (ECTFE), or ethylene-acrylic acid copolymer, ethylene-methacrylic acid copolymer, ethylene-methyl acrylate copolymer, the Na ionomer body of ethylene-methyl methacrylate methyl terpolymer and these copolymers etc., can use a kind in them, also two or more kinds may be used.

Among these adhesive, preferably by P(TFE-VDF) and P(TFE-VDF) VDF based polymer in addition using.

The adhesive of the more anode mixture layer use as lithium secondary battery of VDF based polymer take PVDF as representative, use and contain in the positive pole of Ni as the lithium-contained composite oxide of transition metal at positive active material, if adhesive uses VDF based polymer, the cross-linking reaction of VDF based polymer easily occurs, and it is excessively large that the adaptation of anode mixture layer and collector body becomes.If use such positive pole and jointly form rolled electrode body with negative pole, barrier film, especially easily producing the defects such as be full of cracks at the anode mixture layer of inner circumferential side.; if use VDF based polymer and P(TFE-VDF simultaneously) as the adhesive of anode mixture layer; can moderate inhibition by P(TFE-VDF) the anode mixture layer that causes of effect and the adaptation of collector body, thereby can suppress well the generation of the defect of aforementioned anode mixture layer.

If the containing ratio of the adhesive in anode mixture layer (is the total containing ratio of whole adhesives in the case of using multiple adhesive.About the containing ratio of the adhesive in anode mixture layer, lower same.) too much, the adaptation of anode mixture layer and collector body becomes too high, has the worry that easily produces foregoing problem, thereby, be preferably below 4 quality %, more preferably below 3 quality %.

On the other hand, from improving the viewpoint of anodal capacity, thereby preferably reduce the content of the amount of binder raising positive active material in anode mixture layer, if but amount of binder in anode mixture layer is very few, exist the flexibility of anode mixture layer to reduce, for example use the shape (the especially shape of outer circumferential side) of this anodal rolled electrode body to worsen, the worry of the productivity ratio of infringement lithium secondary battery.Therefore, more than the containing ratio of the adhesive in anode mixture layer is preferably 1 quality %, more preferably more than 1.4 quality %.

In addition, in the case of and with P(TFE-VDF) and the adhesive of VDF based polymer as anode mixture layer, when using their total as 100 quality %, preferably by P(TFE-VDF) ratio be made as 10 quality % more than, more than being more preferably made as 20 quality %.In this way, though as comprise contain Ni also can moderate inhibition as the lithium-contained composite oxide of transition metal and the anode mixture layer of VDF based polymer and the adaptation of collector body.

But, if P(TFE-VDF) and the total of VDF based polymer in P(TFE-VDF) amount too much, the dhering strength of anode mixture layer and collector body reduces, thereby cell resistance is increased, and becomes the reason that the part throttle characteristics of battery is reduced.Therefore, using the P(TFE-VDF in anode mixture layer) and the total of VDF based polymer during as 100 quality %, preferably P(TFE-VDF) ratio be made as below 30 quality %.

The > such as < anode mixture layer, collector body

Positive pole can be through for example following operation manufacture: the composition that contains anode mixture that aforesaid positive active material, adhesive and conductive auxiliary agent are scattered in the pasty state that forms in METHYLPYRROLIDONE (NMP) equal solvent, Slurries by modulation (wherein, adhesive can be dissolved in solvent), be coated on the one or two sides of collector body, after dry, implement as required calendering process.But, anodal manufacture method is not limited to preceding method, also can manufacture by other manufacture methods.

In addition,, after calendering process, the thickness of anode mixture layer is preferably 15～200 μ m at every of collector body.Further, after calendering process, the density of anode mixture layer is preferably 3.2g/cm ³above, 3.6g/cm more preferably ³above.By making the positive pole with so highdensity anode mixture layer, can make the capacity of lithium secondary battery further improve.But, if the density of anode mixture layer is excessive, void content diminishes, thus the worry that exists the impregnability of nonaqueous electrolytic solution to reduce, thereby after calendering process, the density of anode mixture layer is preferably 4.2g/cm ³below.Here, as calendering process, for example, can carry out roll-in with the line pressure of 1～30kN/cm left and right, by such processing, can make the anode mixture layer with aforementioned density.

In addition, the density of the said anode mixture layer of this specification is the value of measuring by the following method.Electrode is cut into regulation area, measures its quality with the electronics Libra of minimum scale 0.1mg, deduct the quality of collector body, thereby calculate the quality of anode mixture layer.On the other hand, the gross thickness of electrode is carried out to 10 mensuration with the micrometer of minimum scale 1 μ m, the mean value of the value from these measured values deduct the thickness of collector body and area calculate the volume of anode mixture layer.And, calculate the density of anode mixture layer divided by aforementioned volume by the quality with aforementioned anode mixture layer.

In anodal collector body, can use the same material of material using with the positive pole of in the past known lithium secondary battery, preference as thickness be the aluminium foil of 10～30 μ m.

Here the positive pole the present invention relates to, is provided with other members and the anodal lead-in wire body (positive wire body) being electrically connected for making lithium secondary battery.Positive wire style, as being made up of metal paper tinsels (plate) such as nickel, is provided with in a part for positive electrode collector the exposed division that does not form anode mixture layer conventionally, thereby is waited aforementioned foil is engaged and installed by welding at this exposed division.

The thickness of positive wire body is preferably 40～200 μ m.In addition, the width of positive wire body is preferably 4～8mm.

< negative pole >

In the negative pole relating at lithium secondary battery of the present invention, for example can use the electrode in the one or two sides of collector body with the structure of anode mixture layer, this anode mixture layer contains negative electrode active material, adhesive, further contains as required conductive auxiliary agent etc.

As negative electrode active material, can enumerate the such as graphite matter material with carbon element (native graphite such as flaky graphite, by RESEARCH OF PYROCARBON class, MCMB (MCMB), carbon fiber etc. easily graphitized carbon at 2800 ℃ of Delaniums that carry out above graphitization processing etc.), the sintered body of RESEARCH OF PYROCARBON class, coke class, vitreous carbon class, organic high molecular compound, MCMB, carbon fiber, active carbon, can with the metal of lithium alloyage (Si, Sn etc.) or its alloy, oxide etc., can use one kind or two or more in them.

Among aforementioned negative electrode active material, especially for realizing the high capacity of lithium secondary battery, preferably using the material that contains Si and O in component (is wherein, 0.5≤x≤1.5 with respect to the atomic ratio x of the O of Si.Below this material is called to " SiO _x").

SiO _xcan contain crystallite or the amorphous phase of Si, in this case, the atomic ratio of Si and O becomes the ratio that comprises the crystallite of Si or the Si of amorphous phase., at SiO _xin contain at amorphous SiO ₂in matrix, be dispersed with for example crystallite Si of Si() structure, as long as this amorphous SiO ₂be scattered in Si wherein and be combined that to meet aforesaid atomic ratio x be 0.5≤x≤1.5.For example,, when as at amorphous SiO ₂in matrix, be dispersed with structure and the SiO of Si ₂in the situation of the mol ratio of the Si material that is 1:1, x=1, thereby, as structural formula, represent with SiO.In the case of the material as this structure, for example, in X-ray diffraction analysis, existence does not observe by Si(crystallite Si) existence and the situation at the peak that causes, if but observe with transmission electron microscope, can confirm the existence of fine Si.

And, SiO _xbe preferably and the complex of material with carbon element Composite, for example, expect SiO _xsurface by material with carbon element coating.SiO _xlack conductivity, therefore, when used as negative electrode active material, from guaranteeing the viewpoint of good battery behavior, need to use conductive material (conductive auxiliary agent), make the SiO in negative pole _xmixing, good dispersion with conductive material, form excellent conductive network.If make SiO _xwith the complex of material with carbon element Composite, with for example use simply by SiO _xthe material being obtained by mixing with conductive materials such as material with carbon elements situation compared with, in negative pole, form more well conductive network.

Use SiO at negative pole _xin the situation of the complex of material with carbon element, about SiO _xwith the ratio of material with carbon element, from bringing into play well the viewpoint by the effect producing with the Composite of material with carbon element, with respect to SiO _x100 mass parts, more than material with carbon element is preferably 5 mass parts, more preferably more than 10 mass parts.In addition, if in aforementioned complex with SiO _xthe ratio of the material with carbon element of Composite is too much, the SiO in existence and anode mixture layer _xthe reduction of amount explicitly, the worry that diminishes of the effect of high capacity, thereby, with respect to SiO _x100 mass parts, material with carbon element is preferably below 50 mass parts, more preferably below 40 mass parts.

Use SiO at negative electrode active material _x(preferably SiO _xcomplex with material with carbon element) situation under, preferably go back and use graphite matter material with carbon element.Because SiO _xbe in a ratio of high power capacity with the material with carbon element of the general negative electrode active material as lithium secondary battery, and follow the volume change of battery charging and discharging large, so, SiO there is in use _xthe lithium secondary battery of negative pole of the high anode mixture layer of containing ratio in, exist due to repeated charge, negative pole (anode mixture layer) thus that volume significantly changes is deteriorated, the worry of volume lowering (being that charge/discharge cycle characteristics reduces).The general negative electrode active material as lithium secondary battery of graphite matter material with carbon element, capacity is larger, and follows the volume change of battery charging and discharging to compare SiO _xlittle.Therefore, by negative electrode active material and use SiO _xwith graphite matter material with carbon element, the capacity that can suppress as much as possible battery improves effect along with SiO _xuse amount reduce and diminish, and suppress well the reduction of the charge/discharge cycle characteristics of battery, therefore, can make the lithium secondary battery of high power capacity more and excellent charge/discharge cycle characteristics.

As with aforementioned SiO _xthe common graphite matter material with carbon element using as negative electrode active material, can enumerate the native graphites such as such as flaky graphite, by RESEARCH OF PYROCARBON class, MCMB (MCMB), carbon fiber etc. easily graphitized carbon at 2800 ℃ of Delaniums that carry out above graphitization processing etc.

When in negative electrode active material by SiO _xwith the complex of material with carbon element, with the situation of graphite matter material with carbon element use under, from guaranteeing well by using SiO _xthe viewpoint of the effect of the high capacity bringing is set out, all SiO in negative electrode active material _xmore than being preferably 0.01 quality % with the containing ratio of the complex of material with carbon element, more preferably more than 1 quality %, more preferably more than 3 quality %.In addition, from avoiding more well following the SiO discharging and recharging _xthe viewpoint of the caused problem of change in volume set out, all SiO in negative electrode active materials _xbe preferably below 20 quality % with the containing ratio of the complex of material with carbon element, more preferably below 15 quality %.

The containing ratio of negative electrode active material in anode mixture layer (all total containing ratios of negative electrode active material) is preferably 80～99 quality %.

The adhesive > of < anode mixture layer

The adhesive using as anode mixture layer, can enumerate for example starch, polyvinyl alcohol, polyacrylic acid, carboxymethyl cellulose (CMC), hydroxypropyl cellulose, regenerated cellulose, the polysaccharides such as diacetyl cellulose, their modification body, polyvinyl chloride, polyvinylpyrrolidone, polytetrafluoroethylene, Kynoar, polyethylene, polypropylene, polyamidoimide, the thermoplastic resins such as polyamide, their modification body, polyimides, ethylene-propylene-diene terpolymer (EPDM), sulfonated epdm, butadiene-styrene rubber (SBR), butadiene rubber, polybutadiene, fluorubber, poly(ethylene oxide) etc. have the polymer of rubber-like elasticity, their modification body etc., can use one kind or two or more in them.

The containing ratio of the adhesive in anode mixture layer is preferably 1～20 quality %.

The conductive auxiliary agent > of < anode mixture layer

In anode mixture layer, can further add conductive material as conductive auxiliary agent.As such conductive material, as long as the material that does not cause chemical change in lithium secondary battery is just not particularly limited, can use the materials such as one kind or two or more such as carbon black (thermal black, oven process carbon black, channel carbon black, Ketjen black, acetylene black etc.), carbon fiber, metal powder (copper, nickel, aluminium, silver etc.), metallic fiber, polyphenyl derivative (material that Japanese kokai publication sho 59-20971 communique is recorded).In the middle of them, preferably use carbon black, more preferably Ketjen black, acetylene black.

The > such as < anode mixture layer, collector body

Negative pole can be manufactured through for example following operation: the composition that contains cathode agent that the conductive auxiliary agent that modulation by aforementioned negative electrode active material and adhesive, is further used is as required scattered in the pasty state that forms in NMP, water equal solvent, Slurries (wherein, adhesive can be dissolved in solvent), be coated on the one or two sides of collector body, after dry, implement as required calendering process.But, the manufacture method of negative pole is not limited to preceding method, also can manufacture by other manufacture methods.The thickness preference of anode mixture layer as every of collector body be 10～100 μ m.

As the collector body of negative pole, can use the paper tinsel of copper, nickel system, die-cut metal, net, drawn metal etc., conventionally use Copper Foil.About this negative electrode collector, make the thin thickness of negative pole entirety at the battery in order to obtain high-energy-density, the upper limit of thickness is preferably 30 μ m, in order to ensure mechanical strength, is limited to 5 μ m under expectation.

Here the negative pole the present invention relates to, is provided with other members and the anodal lead-in wire body (negative wire body) being electrically connected for making lithium secondary battery.Negative wire body can for example be made up of metal paper tinsels (plate) such as nickel, is conventionally provided with in a part for negative electrode collector the exposed division that does not form anode mixture layer, thereby this exposed division is waited aforementioned foil is engaged and installed by welding.

The thickness of negative wire body is preferably 40～200 μ m.In addition, the width of negative wire body is preferably 4～8 μ m.

< flat rolled electrode body >

The flat rolled electrode body that lithium secondary battery of the present invention relates to is that aforementioned positive pole and aforementioned negative pole is overlapping and be wound into helical form and become with cross section the flat rolled electrode body that the mode of flat forms across aforementioned barrier film.Here, as shown in Figure 1, the flat rolled electrode body the present invention relates to positive wire body 51 and negative wire body 52 from equidirectional, the side-prominent mode of same end face forms.

And, the end face 302 that the positive wire body 51 in flat rolled electrode body 30 and negative wire body 52 have been given prominence to and relative to each other and width 2 sides 301,301 use adhesive tapes 60 wider than other faces be fixed.

In adhesive tape 60, there is the resin that contains not melting of the temperature below the closing temperature of lithium secondary battery, fusing point is higher or there is no the base material of (not melting) resin of fusing point than closing temperature, is formed with adhesive phase at its one side.Adhesive tape if so, even if become closing temperature above in the situation that in lithium secondary battery, at least till the fusing point (in the situation that composition resin has fusing point) of composition resin that reaches the base material that adhesive tape relates to, adhesive tape can keep its shape well, therefore, near the thermal contraction of the barrier film of the outstanding end face of positive wire body and negative wire body can be suppressed well, safe lithium secondary battery can be formed.

As the base material of the adhesive tape the present invention relates to, for example can enumerate sheet (film) take PP, polyphenylene sulfide (PPS), polyester (PETG, polybutylene terephthalate (PBT) etc.), polyamide (nylon 66 etc.), polyimides (Thermocurable polyimide, thermoplastic polyimide) etc. as composition resin, weave cotton cloth, nonwoven fabrics etc.

In addition the sticker of adhering agent layer that, forms adhesive tape is as long as the material (acrylic acid series sticker, rubber series sticker, silicone-based sticker etc.) identical with the sticker adopting in the inside of lithium secondary battery was used adhesive tape in the past.

In Fig. 2 and Fig. 3, show pattern and represented the stereogram of other examples of the flat rolled electrode body that lithium secondary battery of the present invention relates to.In the flat rolled electrode body the present invention relates to, the quantity, the fixed position that are fixed part with adhesive tape can suitably determine according to the configuration of positive wire body and negative wire body.About by the fixing part of adhesive tape, for example can be illustrated in figure 11 place, can be also 2 places as shown in Figures 2 and 3, further, more than can also being made as 3 places.But, if excessively increased by the quantity that adhesive tape is fixed part, there is the worry of the productivity ratio of infringement flat rolled electrode body and the productivity ratio of lithium secondary battery, therefore, be fixed more preferably 1～2 place of part with adhesive tape.

Here, by be fixed part with adhesive tape and be made as 1 place in the situation that, from suppressing more well the viewpoint of thermal contraction of barrier film, the position that is preferably fixed is made as: in the side-looking (from the wider side of width is seen) of flat rolled electrode body, when using the length of the Width of flat rolled electrode body as 100% time, become 40% position from central portion to the Width of flat rolled electrode body.

The width A(mm of adhesive tape) (in Fig. 1, be the length of A.The in the situation that of fixing with adhesive tape in many places, it is the width of each adhesive tape.Lower same.) be preferably more than 0.05 with the ratio A/W of the width W (mm) of battery case, more preferably more than 0.10.The adhesive tape that meets the width of this condition by use and the relation of the width W of battery case, can suppress the thermal contraction of barrier film more well.

In addition, be not particularly limited about the higher limit of the ratio A/W of the width A of adhesive tape and the width W of battery case, if but consider productivity ratio etc., be 0.5 left and right.Further, be in multiple situation when be fixed part with adhesive tape, as long as in the value of A/W meets the scope of aforementioned lower limit, the width A that suitably selection can realize.

In flat rolled electrode body, preferably the porous layer (II) of barrier film is to be at least configured towards anodal mode.By to make to contain heat resisting temperature be 150 ℃ of above fillers as main body and the more excellent porous layer (II) of oxidative resistance towards positive pole, can suppress more well the oxidation of the barrier film being caused by positive pole, therefore, also can improve preservation characteristics, the charge/discharge cycle characteristics of battery in the time of high temperature.In addition, as described later, in the nonaqueous electrolytic solution relating at lithium secondary battery, can also add the additive such as vinylene carbonate, cyclohexyl benzene, thereby but exist these additives to form epithelium and the pore of barrier film is stopped up to the worry of the reduction that causes battery behavior at side of the positive electrode.Therefore, by making the comparatively porous layer of porous (II) towards positive pole, can also expect the effect of the hole plug that suppresses pore.

On the other hand, be porous layer (I) on a surface of barrier film, preferably be made as the mode of porous layer (I) towards negative pole, in this way, for example suppress while closing to be absorbed by the mixture layer of electrode from the thermoplastic resin of porous layer (I) melting, thereby can be effectively in the obturation of the emptying aperture of barrier film, utilize.

< nonaqueous electrolytic solution >

In the nonaqueous electrolytic solution relating at lithium secondary battery of the present invention, for example, can use lithium salts is dissolved in to the solution in organic solvent.

As nonaqueous electrolytic solution lithium salts used, the material that form lithium ion as long as dissociating in solvent, is difficult to occur the side reactions such as decomposition in the voltage range using as battery is just not particularly limited.Can use for example LiClO ₄, LiPF ₆, LiBF ₄, LiAsF ₆, LiSbF ₆deng inorganic lithium salt, LiCF ₃sO ₃, LiCF ₃cO ₂, Li ₂c ₂f ₄(SO ₃) ₂, LiN(CF ₃sO ₂) ₂, LiC(CF ₃sO ₂) ₃, LiC _nf _2n+1sO ₃(n≤2), LiN(RfOSO ₂) ₂organic lithium salts such as (here, Rf are fluoro-alkyl) etc.

Concentration as this lithium salts in nonaqueous electrolytic solution, is preferably made as 0.5～1.5mol/l, is more preferably made as 0.9～1.25mol/l.

As nonaqueous electrolytic solution organic solvent used, as long as the material that aforementioned lithium salts dissolves, do not occur in the voltage range using as battery the side reactions such as decomposition is just not particularly limited.Can enumerate for example ethylene carbonate, propylene carbonate, the cyclic carbonates such as butylene carbonate, dimethyl carbonate, diethyl carbonate, the linear carbonate such as methyl ethyl carbonate, the chain esters such as methyl propionate, the cyclic esters such as gamma-butyrolacton, dimethoxy-ethane, ether, 1, 3-dioxolanes, diethylene glycol dimethyl ether, triglyme, the chain ethers such as tetraethylene glycol dimethyl ether, diox, oxolane, the cyclic ethers such as 2-methyltetrahydrofuran, acetonitrile, propionitrile, the nitriles such as methoxypropionitrile, the sulfurous esters such as glycol sulfite ester etc., they can mix two or more and use.Here,, in order to make the better battery of characteristic, the mixed solvent of expectation use ethylene carbonate and linear carbonate etc. can obtain the combination of high conductivity.

In addition the nonaqueous electrolytic solution that, lithium secondary battery uses preferably contains vinylene carbonate (VC).In the lithium secondary battery of the nonaqueous electrolytic solution that contains VC in use, form the epithelium from VC in negative terminal surface, by this epithelium, deteriorated etc. suppressed due to the nonaqueous electrolytic solution of following the negative pole of battery charging and discharging to cause with reacting of nonaqueous electrolytic solution, therefore, can improve charge/discharge cycle characteristics.

More than in the nonaqueous electrolytic solution that lithium secondary battery uses, the containing ratio of VC is preferably 1 quality %, more preferably more than 1.5 quality %.But, if the amount of VC is too much in nonaqueous electrolytic solution, while there is formation epithelium, produce excessive gas, thereby become the worry of the reason of battery case expansion.Therefore, in the nonaqueous electrolytic solution that lithium secondary battery uses, the containing ratio of VC is preferably below 10 quality %, more preferably below 5 quality %.

Further, the nonaqueous electrolytic solution that lithium secondary battery uses preferably contains the cyclic carbonate that halogen replaces.Especially use SiO at negative electrode active material _xthe situation of lithium secondary battery under, discharge and recharge SiO even if follow _xthereby particle fracture etc. forms newborn face, also can be reduced by the charge/discharge cycle characteristics that forms caused battery of so newborn face because the epithelium of the cyclic carbonate replacing from halogen covers this new life's face thereby suppresses.

As the cyclic carbonate replacing with halogen, particularly preferably 4-fluoro-1,3-dioxolan-2-one (FEC).

Containing ratio in the nonaqueous electrolytic solution that the cyclic carbonate replacing about halogen uses at lithium secondary battery, from guaranteeing more well by the viewpoint that uses its aforementioned effect of bringing, more than being preferably 1 quality %, more preferably more than 1.5 quality %.But, if the amount of the cyclic carbonate that in nonaqueous electrolytic solution, halogen replaces is too much, especially use SiO at negative electrode active material _xsituation under, there is SiO _xthe worry of activity decreased.Therefore, the containing ratio in the nonaqueous electrolytic solution that the cyclic carbonate that halogen replaces uses at lithium secondary battery is preferably below 5 quality %, more preferably below 3 quality %.

In addition the nonaqueous electrolytic solution that, lithium secondary battery uses preferably contains represented phosphine acyl acetic acid ester (phosphonoacetate) compounds of following general formula (3).

[changing 1]

In aforementioned formula (3), R ¹～R ³the alkyl, the alkenyl or alkynyl that represent independently of one another the carbon number 1～12 that can be replaced by halogen atom, n represents 0～6 integer.

As the represented phosphine acyl acetic acid ester type compound of following general formula (3), preferably 2-propynyl 2-(diethoxy phosphoryl) acetic acid esters, ethyl diehylphosphonoacetate.

More than the content of the represented phosphine acyl acetic acid ester type compound of aforementioned formula in the nonaqueous electrolyte that lithium secondary battery uses (1) is preferably 0.5 quality %; more preferably more than 1.0 quality %; in addition, be preferably below 30 quality %, more preferably below 5.0 quality %.

Further, in the nonaqueous electrolytic solution using at lithium battery, for example, take improve battery charge/discharge cycle characteristics, suppress high-temperature expansion, prevent from overcharging etc. the raising etc. of fail safe as object, can also suitably from the additives (also comprising their derivative) such as acid anhydrides, sulphonic acid ester, dintrile, PS, diphenyl disulfide, cyclohexyl benzene, biphenyl, fluorobenzene, tert-butyl benzene, succinonitrile, select suitable material and add.

< battery case >

In Fig. 4, represent respectively the stereogram of the outward appearance of an example of lithium secondary battery of the present invention display mode, in Fig. 5, show the part sectional arrangement drawing of the lithium secondary battery shown in Fig. 4.Lithium secondary battery 1 shown in Fig. 4 and Fig. 5 has the battery case 10 of column, and battery case 10 accommodates flat rolled electrode body 30 and nonaqueous electrolytic solution (not shown) etc. for hollow and inside.

Battery case 10 is made up of outer packing shell 11 and lid 20, and outer packing shell 11 has there the is bottomless drum shape form of (angle tubular), and its open end is coated with lid 20, integrated by welding and lid 20.Outer packing shell 11 and lid 20 are for example made up of aluminium alloy etc.

The terminal 21 being made up of stainless steel etc. is outstanding from lid 20, and between terminal 21 and lid 20, interval has the insulating package 22 being made up of PP etc.In addition, on terminal 21, across insulator 24, the lead plate 25 being made up of stainless steel etc. is installed.Terminal 21 is for example connected with negative pole in battery case 10, and in this case, terminal 21 plays a role as negative terminal, and outer packing shell 11 and lid 20 play a role as positive terminal.But, according to the difference of the material of battery case 10 etc., also have terminal 21 in battery case 10 with anodal being connected as the situation that positive terminal plays a role, outer packing shell 11 and lid 20 play a role as negative terminal.In addition, in lid 20, be provided with nonaqueous electrolytic solution inlet, after the interior injection nonaqueous electrolytic solution of battery case 10, seal with containment member 23.

The flat rolled electrode body 30 being contained in battery case 10 is made up of positive pole 31, negative pole 32 and barrier film 33, and the bottom of the outer packing shell 11 relating at battery case 10, disposes the insulator 40 being formed by PE sheet etc.And about lithium secondary battery 1, by the anodal 31 positive wire bodies 51 that have are directly welded in to lid 20, thereby outer packing shell 11 and lid 20 play a role as positive terminal; Be welded in lead plate 25 by the negative wire body 52 that negative pole 32 is had, make negative wire body 52 and terminal 21 conducting via this lead plate 25, thereby terminal 21 play a role as negative terminal.

In addition, the side surface part of battery case 10, the side surface part of outer packing shell 11 have relative to each other and from the side width than wider 2 wide 111,111 of other faces (face 112,112 in Fig. 4).And, be provided with the cracking ditch 12 of cracking when large for the pressure ratio threshold value in battery case 10 wide 111,111 at least one party (being above wide 111 in figure) in Fig. 4.

But, in Fig. 5, for fear of complicated, in figure, be not illustrated in the collector body using while making positive pole 31, negative pole 32, in addition, each layer of also as broad as long demonstration of barrier film.Further, the part of the inner circumferential side of flat rolled electrode body is not in section.

Here, the width of the battery case the present invention relates to (in Fig. 5, the length of transverse direction) is more than 40mm, and this higher limit is generally 70mm left and right.

Lithium secondary battery of the present invention can be for the purposes identical with the in the past known various uses that is suitable for lithium secondary battery.

Embodiment

Below, based on embodiment, the present invention is described in detail.But, following embodiment does not limit the present invention.

Embodiment 1

The making > of < positive pole

As lithium-contained composite oxide, by Li _1.02ni _0.6co _0.2mn _0.2o ₂and LiCoO ₂weigh according to the mass ratio of 20:80, with Henschel mixer (Henshel mixer) mixing 30 minutes, obtain mixture.Using the mixture obtaining (positive active material) 100 mass parts, as adhesive using PVDF and P(TFE-VDF) be dissolved in solution 20 mass parts in NMP, be that carbon fiber 1.04 mass parts and the graphite 1.04 mass parts twin-screw mixer machine that 100nm and fiber diameter are 10nm carries out mixing as the average fiber length of conductive auxiliary agent, further add NMP adjusting viscosity, thus the paste that modulation contains anode mixture.Here, about PVDF and P(TFE-VDF) the use amount of nmp solution, the PVDF dissolving and P(TFE-VDF) amount be made as at aforementioned lithium-contained composite oxide A and LiCoO ₂mixture, with PVDF and P(TFE-VDF) and total (, the total amount of anode mixture layer) the 100 quality % of aforementioned conductive auxiliary agent in be respectively the amount of 2.34 quality % and 0.26 quality %.That is, in aforementioned positive pole, the adhesive total amount in anode mixture layer is 2.6 quality %, P(TFE-VDF) and the total 100 quality % of PVDF in, P(TFE-VDF) ratio be 10 quality %.

The aforementioned paste that contains anode mixture is carried out to thickness and regulate the two sides that is also intermittently coated on the aluminium foil that thickness is 15 μ m (positive electrode collector), after dry, carry out calendering process, regulate the thickness of anode mixture layer take total thickness as the mode of 130 μ m, mode take width as 54.5mm is cut off, thereby makes anodal.It is further the lead-in wire body of 80 μ m and the width nickel foil system that is 6mm at the exposed division throat thickness of this anodal aluminium foil.

The making > of < negative pole

Be that take the complex of material with carbon element coating, (amount of the material with carbon element in complex is as 10 quality % on the surface at SiO of 8 μ m by average grain diameter.Hereinafter referred to as " SiO/ material with carbon element complex ".) and average grain diameter be the graphite of 16 μ m take the amount of SiO/ material with carbon element complex as the amount of 5 quality % is mixed to get negative electrode active material, these negative electrode active material 98 mass parts, viscosity are adjusted to the CMC aqueous solution 100 mass parts of 1 quality % concentration of the scope of 1500～5000mPas and SBR 1.0 mass parts take resistivity as 2.0 × 10 ⁵ion exchange water more than Ω cm mixes as solvent, thus the paste that contains cathode agent of modulation aqueous systems.

The aforementioned paste that contains cathode agent is carried out to thickness and regulate the two sides that is also intermittently coated on the Copper Foil that thickness is 8 μ m (negative electrode collector), after dry, carry out calendering process, adjust the thickness of anode mixture layer take total thickness as the mode of 110 μ m, mode take width as 55.5mm is cut off, thereby makes negative pole.It is further the lead-in wire body of 80 μ m and the width nickel foil system that is 6mm at the exposed division throat thickness of the Copper Foil of this negative pole.

The making > of < barrier film

Be in the 5kg boehmite secondary aggregation body of 3 μ m in average grain diameter, add 5kg ion exchange water and 0.5kg dispersant (aqueous systems polycarboxylic acids ammonium salt, solid component concentration 40 quality %), by the ball mill pulverization process of 40 beats/min of internal volume 20L, revolution 10 hours, thus modulation dispersion liquid.A part for dispersion liquid after treatment is carried out to vacuumize at 120 ℃, observes by scanning electron microscope (SEM), result, boehmite be shaped as general plate.In addition, the average grain diameter of boehmite after treatment is 1 μ m.

In aforementioned dispersion liquid 500g, add 0.5g xanthans, add 17g resin-bonding agent dispersing liquid (modified polypropene acid butyl ester, solid component content 45 quality %) as adhesive as thickener, with 31 motor (THREE-ONE MOTOR) stirring 3 hours, thereby modulate uniform slip (porous layer (II) formation slip, solid constituent ratio is 50 quality %).

One side at the micro-porous barrier film of secondary lithium batteries PE system (porous layer (I): 135 ℃ of the fusing points of thickness 12 μ m, void content 40%, average pore size 0.08 μ m, PE) is implemented Corona discharge Treatment (discharge capacity 40Wmin/m ²),, be dried at the applying porous matter layer of this treated side (II) formation slip with miniature intaglio plate coating machine, forming thickness is the porous layer (II) of 2 μ m, thereby obtains the barrier film of cascade type.The quality of porous layer (II) per unit area in this barrier film is 5.5g/m ²and the volume containing ratio of boehmite is 95 volume %, and void content is 45%.

The assembling > of < battery

The positive pole obtaining in the foregoing manner and negative pole is overlapping and be wound into helical form across barrier film towards anodal mode with the porous layer (II) of barrier film, thus rolled electrode body made.The rolled electrode body obtaining is squeezed into flat, as shown in Figure 2, is fixed by the middle position between positive wire body and negative wire body with apart from the adhesive tape of width 6mm, length 30mm for position of negative wire body 10mm.Adhesive tape uses take 165 ℃ of PP(fusing points) (thickness 30 μ are m) as the adhesive tape of base material for the film of system.

Aforementioned flat rolled electrode body is put into the aluminium alloy outer packing shell processed of thickness 5.1mm, width 51mm, height 61mm.As nonaqueous electrolytic solution, modulate following solution: in the solvent that ethylene carbonate, methyl ethyl carbonate and diethyl carbonate are mixed according to volume ratio=1:1:1 by LiPF ₆to become in the solution that the mode of concentration of 1.1mol/l dissolves, add FEC, add VC, further add 2-propynyl 2-(diethoxy phosphoryl to become the amount of 1.0 quality % to become the amount of 1.0 quality % to become the amount of 1.0 quality % wherein) acetic acid esters; This solution is injected to aforementioned aluminium alloy outer packing shell processed.Inject after nonaqueous electrolytic solution, carry out the sealing of outer packing shell, thus the lithium secondary battery of structure shown in outward appearance, Fig. 5 shown in construction drawing 4.In this lithium secondary battery, the fixing width A of adhesive tape using of pancake electrode coiling body and the ratio A/W of the width W of battery case are 0.117.

Embodiment 2

As shown in Figure 1, the fixed position of the adhesive tape in flat rolled electrode body is only located between positive wire body and negative wire body, in addition, operation similarly to Example 1, makes lithium secondary battery.

Embodiment 3

The size of battery case is made as to thickness 5.6mm, width 56mm, height 64mm, and in addition, operation similarly to Example 1, makes lithium secondary battery.In this lithium secondary battery, the fixing width A of adhesive tape using of pancake electrode coiling body and the ratio A/W of the width W of battery case are 0.107.

Embodiment 4

The width A of the adhesive tape fixing used of flat rolled electrode body is changed to 8mm, and in addition, operation similarly to Example 2, makes lithium secondary battery.In this lithium secondary battery, the fixing width A of adhesive tape using of pancake electrode coiling body and the ratio A/W of the width W of battery case are 0.156.

Comparative example 1

With adhesive tape, flat rolled electrode body is not fixed, in addition, operated similarly to Example 1, make lithium secondary battery.

Comparative example 2

Porous layer (II) is not set in barrier film, in addition, operates similarly to Example 1, make lithium secondary battery.

Reference example

The thickness of porous layer (II) is changed to 10 μ m, in addition, operate similarly to Example 1, make barrier film, except using this barrier film, similarly operate with comparative example 1, make lithium secondary battery.

For each lithium secondary battery of embodiment 1～4 and comparative example 2, battery is placed in to baking box, measure while being heated to 150 ℃ with the speed of 5 ℃/min when the internal resistance of battery rises to room temperature more than 5 times time temperature, using this temperature as closing temperature.Consequently, the closing temperature of these batteries is 140 ℃.

In addition,, for each lithium secondary battery of embodiment 1～4, comparative example 1,2 and reference example (having carried out the battery beyond battery that closing temperature measures), carry out by the following method 150 ℃ of heat runs.For each battery, carry out the following electric current-constant-voltage charge of determining: first, after discharging and recharging for the first time, under normal temperature (25 ℃) with the constant-current charge of 1C to reaching 4.4V, carry out afterwards the constant-voltage charge (total charging time: 2.5 hours) with 4.4V.And, the each battery after charging is put into thermostat, from 30 ℃ to 150 ℃, the ratio with 1 ℃ per minute makes temperature rise and heats, and keeps 30 minutes afterwards at 150 ℃.Afterwards, each battery is decomposed from thermostat takes out, confirm the thermal contraction degree of the barrier film in flat rolled electrode body by range estimation, evaluate according to following standard.Can think that the safety of lithium secondary battery that is evaluated as " ◎ " and "○" carrying out according to following standard is good.

Almost can not confirm the thermal contraction of barrier film: ◎,

Barrier film has small thermal contraction, but is not to produce the degree contacting anodal and negative pole: zero,

Barrier film thermal contraction, reaches the degree that has the worry contacting that produces positive pole and negative pole: △,

Barrier film thermal contraction, reaches the degree contacting anodal and negative pole that produces: ×.

Aforementioned evaluation result is shown in to table 1.

[table 1]

As shown in table 1, use in the lithium secondary battery of reference example of thicker barrier film at porous layer (II), even flat rolled electrode body is fixed without adhesive tape, in 150 ℃ of heat runs, also can not there is the thermal contraction of barrier film until the anodal degree contacting with negative pole, but make in the battery of comparative example 1 of the barrier film that porous layer (II) is thin in use, although do not reach use and do not form the degree of the battery of the comparative example 2 of the barrier film of porous layer (II), but, there is the anodal worry contacting with negative pole in barrier film thermal contraction.

On the other hand, have with the adhesive tape of appropriate characteristics in the lithium secondary battery of the embodiment 1～4 of the flat rolled electrode body that suitably part is fixed, even if use the barrier film identical with the battery of comparative example 1, in 150 ℃ of heat runs, also suppress well the thermal contraction of barrier film, there is high security.Especially the width A of adhesive tape and the ratio A/W of the width W of battery case are made as to the more suitably lithium secondary battery of the embodiment 1～3 of value, have suppressed more to heavens the thermal contraction of barrier film than the lithium secondary battery of embodiment 4, can guarantee very excellent fail safe.

Claims (3)

1. a lithium secondary battery, is characterized in that,

It is enclosed the lithium secondary battery that the battery case of hollow columnar forms for flat rolled electrode body and nonaqueous electrolytic solution, described flat rolled electrode body is the negative pole that has the positive pole of positive wire body and have a negative wire body across barrier film and overlapping and be wound into helical form and form to the outstanding mode of equidirectional with described positive wire body and described negative wire body

Described barrier film has the porous layer (I) using thermoplastic resin as main body and contains the porous layer (II) of heat resisting temperature as more than 150 ℃ fillers as main body, and the thickness of described porous layer (II) is below 8 μ m,

In described flat rolled electrode body, the end face that described positive wire body and described negative wire body have been given prominence to and relative to each other and width 2 sides wider than other faces adhesive tape with base material fix, the resin that described base material contains the not melting of temperature below closing temperature

The width of described battery case is more than 40mm.

2. lithium secondary battery according to claim 1, wherein the width A(mm of adhesive tape) with the ratio A/W of the width W (mm) of battery case be more than 0.05.

3. lithium secondary battery according to claim 1 and 2, the thickness of its septation is below 28 μ m.

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