CN1711654A - Negative electrode for nonaqueous electrolyte secondary battery, method for manufacturing same and nonaqueous electrolyte secondary battery - Google Patents

Negative electrode for nonaqueous electrolyte secondary battery, method for manufacturing same and nonaqueous electrolyte secondary battery Download PDF

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Publication number
CN1711654A
CN1711654A CNA2003801029990A CN200380102999A CN1711654A CN 1711654 A CN1711654 A CN 1711654A CN A2003801029990 A CNA2003801029990 A CN A2003801029990A CN 200380102999 A CN200380102999 A CN 200380102999A CN 1711654 A CN1711654 A CN 1711654A
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active material
particle
superficial layer
secondary battery
layer
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CN100340015C (en
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安田清隆
坂口善树
武者信一
土桥诚
茂出木晓宏
松岛智善
本田仁彦
田口丈雄
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Mitsui Mining and Smelting Co Ltd
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Mitsui Mining and Smelting Co Ltd
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    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
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    • Y02E60/10—Energy storage using batteries

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Abstract

A negative electrode for nonaqueous secondary batteries is disclosed. The negative electrode has a pair of current collecting surface layers of which the surfaces are adapted to be brought into contact with an electrolyte and at least one active material layer interposed between the surface layers. The active material layer contains particles of an active material having high capability of forming a lithium compound. The material constituting the surfaces is preferably present over the whole thickness of the active material layer to electrically connect the surfaces so that the electrode exhibits a current collecting function as a whole. The surface layers each preferably have a thickness of 0.3 to 10 mum.

Description

Negative electrode for nonaqueous secondary battery, its manufacture method and nonaqueous electrolytic solution secondary battery
Technical field
The present invention relates to negative electrode for nonaqueous secondary battery such as lithium rechargeable battery.More detailed saying, relate to and to access from the initial stage that discharges and recharges, and the current collection height, and prevented to result from the embedding of lithium ion and taken off the coming off of active material of embedding with regard to the charge/discharge capacity height, cycle life improves, and the negative pole of the high nonaqueous electrolytic solution secondary battery of energy density.In addition, the invention still further relates to the manufacture method of this negative pole and used the nonaqueous electrolytic solution secondary battery of this negative pole.
Background technology
Lithium rechargeable battery is because its energy density and other secondary cell comparative cases are outer high, and therefore the power supply as portable phone and notebook computer etc. uses.In recent years, portable usefulness is electric to be accelerated rapidly with high performance electronic equipment, and also there is significant increase tendency in their power consumption.In order to satisfy such requirement, power supply is necessary with the further high capacity of secondary cell.The lithium rechargeable battery of present situation uses the otide containing lighium thing in positive pole, use the carbon-based material (graphite) in the interlayer that lithium ion can be stored at crystal structure in negative pole.Present practical lithium rechargeable battery is reaching the theoretical capacity value that these materials have, the novel electrode material that waits in expectation and create high power capacity.
So the Sn with 5-10 capacity current potential doubly of graphite is that alloy or Si are that the exploitation of alloy comes to life.For example, a kind of lithium ion secondary battery cathode (opening the 2002-260637 communique referring to the spy) has been proposed, it is a collector body with conductive metal paper tinsels such as Copper Foils, will contain silicon or silicon alloy active material particle, with the mixture of the conductive metal powder of copper and copper alloy etc. on the surface of collector body under non-oxidizing atmosphere sintering and obtaining.In addition, a kind of lithium ion secondary battery cathode (opening the 2002-289178 communique referring to the spy) has also been proposed, it is a collector body with conductive metal paper tinsels such as Copper Foils, adopts galvanoplastic to form the active material layer that comprises tin thin film in the above, adopts galvanoplastic to form the thin layer of copper in the above.
; open in the negative pole of 2002-260637 communique record the spy, active material particle is in the electrolyte, therefore results from the embedding of lithium ion and the expansion of particle of taking off the active material of embedding to shrink; easily cause coming off of this active material particle, the cycle life of battery reduces easily.In addition, the collector body in this negative pole is the thicker collector body of 10-100 μ m, thus active material to account for the ratio of negative pole integral body low, improve energy density thus and be not easy.Open in the negative pole of 2002-289178 communique record the spy, the thickness of the copper lamina of the active material layer of covering tin thin film is 0.01-0.2 μ m as thin as a wafer, and is the distribution of island ground, so the major part of active material layer is in the electrolyte.Therefore, same with the negative pole of patent documentation 1 record, easily cause result from lithium ion embedding and take off the coming off of active material of embedding.
In addition, a kind of negative pole (opening flat 8-50922 communique referring to the spy) has been proposed: in the one side that comprises not with the curren-collecting part of the metallic element of lithium component alloy, formation contains the layer with the metallic element of lithium component alloy, thereby formation does not constitute negative pole with the layer of the metallic element of lithium component alloy on this layer.Think according to this communique,, can suppress to result from discharging and recharging of battery and the layer micronizing of containing of causing and the metallic element of lithium component alloy according to the negative pole of this formation., according to the embodiment of above-mentioned document record, the most surperficial formation not with the thickness of the layer of the metallic element of lithium component alloy as thin as a wafer, be 50nm, so this layer has fully lining to contain possibility with the surface of the layer of the metallic element of lithium component alloy.Under the sort of occasion, when containing layer with the metallic element of lithium component alloy and result from discharging and recharging of battery and micronizing, can not fully suppress coming off of its.On the contrary, not with the layer of the metallic element of lithium component alloy fully lining contain occasion with the surface of the layer of the metallic element of lithium component alloy, this layer hinders electrolyte logical to the laminar flow that contains with the metallic element of lithium component alloy, is difficult to take place sufficient electrode reaction.The technical scheme that so opposite function is taken into account is not suggested as yet.
Different therewith is that as the collector body that lithium rechargeable battery is used, known has: formed the concavo-convex collector body of appropriateness on the surface and be formed on the collector body of the minute aperture that thickness direction connects.For example, thus proposed to be included in the collector body (opening flat 8-236120 communique) that intercommunicating pore that thickness direction connects constitutes the porous electrolytic metal paper tinsel that three-dimensional net structure forms referring to the spy.This metal forming is by following process manufacturing: separate out (being that electro-deposition goes out) metal in drum type cathode surface electrical and form its metal foil layer, it is peeled off when forming the electrolytic metal paper tinsel from the drum type cathode, the drum type cathode surface of exposing after peeling off forms at least that thickness is the oxide-film of 14nm, forms the electrolytic metal paper tinsel in the above., the percent opening of this metal forming or perforate aperture depend on the thickness of the oxide-film that is formed at the drum type cathode, and this oxide-film usually peels off bit by bit with paper tinsel, so the control in percent opening or perforate aperture is difficult.In addition, owing to have three-dimensional net structure with the smaller state of percent opening, therefore the active material cream that is coated with respectively in the table of paper tinsel is difficult to direct contact each other.Therefore think and on the adhesiveness that improves cream and paper tinsel, have the limit.
For solving the problem that above-mentioned metal forming has, the present application people had before proposed a kind of porous copper foil (disclosing brochure No. 00/15875 referring to the world): this porous copper foil is to make that by electro-deposition mutual plane ground composition plane direction average grain diameter is the porous copper foil that the copper particle of 1-50 μ m forms, light transmission is 0.01% or above the time, when forming paper tinsel as the difference of the surface roughness on the surface of the surface roughness on the surface of cathode plane side and its opposition side scope at Rz 5-20 μ m.When using this Copper Foil as the collector body of lithium rechargeable battery, because (1) electrolyte easily circulates, can make limited amount electrolyte soak into (infiltration) to active material equably, (2) giving and accepting of Li ion during difficult obstruction discharges and recharges or electronics, (3) have the concavo-convex of appropriateness on the surface, therefore obtained excellent this favourable effect of adhesiveness with active material., in the manufacture method of this porous copper foil, because behind acid copper on the drum type cathode, this Copper Foil to the state peeled off from this cathode is implemented various processing, therefore the state of Copper Foil becomes unstable, and the property handled is not talkative to be good, and a large amount of production is not easy.In addition, using this porous copper foil as collector body, in the negative electrode for nonaqueous secondary battery that constitutes at its each face coating cathode agent, result from lithium embedding and take off embedding, negative electrode active material easily comes off, the problem that exists cycle characteristics to reduce easily.
Summary of the invention
Therefore, the objective of the invention is to, negative electrode for nonaqueous secondary battery and manufacture method and the nonaqueous electrolytic solution secondary battery that can eliminate the various shortcoming that above-mentioned prior art has are provided.
Found that of the diligent investigation of the inventor, by clamp the layer of active material with 2 superficial layers that also play the collector body function, prevented to result from the embedding of lithium and taken off the coming off of active material of embedding, kept the current collection function simultaneously, and the ratio that active material accounts for electrode integral body improves.
The present invention achieves the above object by a kind of negative electrode for nonaqueous secondary battery is provided, the feature of this negative pole is, possess: a pair of current collection superficial layer that contacts with electrolyte of surface, and between between this superficial layer and contain the active material layer of one deck at least of the high active material particle of the formation ability of lithium compound.Negative pole of the present invention comprises the negative pole of embodiment shown in Figure 1 described later and the negative pole of embodiment shown in Figure 8.The negative pole of embodiment shown in Figure 1 is what not possess as the conductive metal paper tinsel layer of core, and the negative pole of embodiment shown in Figure 8 is what to possess as the conductive metal paper tinsel layer of core.
In addition, the invention provides the preferred manufacture method of a kind of manufacture method of negative electrode for nonaqueous secondary battery as above-mentioned negative pole, it is characterized in that, coating contains the conductivity paste of active material particle on foils, form active material layer, the described foils that has formed this active material layer is immersed in the electroplating bath that contains metal material electroplates (electrolysis plating), form the electrode that contains described active material layer, then from described this electrode of foils peel separation.
In addition, the invention provides a kind of manufacture method of negative electrode for nonaqueous secondary battery preferred another manufacture method as above-mentioned negative pole, it is characterized in that, have the vector resin of a large amount of cation exchange bases on the surface with the liquid handling of metal ion, make it to generate the slaine of this cation exchange base; Reduce this slaine, become on the above-mentioned surface of vector resin catalyst core above-mentioned metal by overlay film; By the power on low metal material of formation ability of plating lithium compound of overlay film, form a side current collection superficial layer at this; This current collection with superficial layer on coating contain the conductivity paste of active material particle, form active material layer; On this active material layer, electroplate the low metal material of formation ability of lithium compound, form the opposing party's current collection superficial layer; Separate above-mentioned vector resin by peeling off or dissolving with superficial layer then from an above-mentioned side's current collection.
In addition, the invention provides a kind of nonaqueous electrolytic solution secondary battery, it is characterized in that, possess above-mentioned negative pole.
Description of drawings
Fig. 1 is the schematic diagram of wanting portion that amplifies the 1st embodiment that shows negative pole of the present invention.
Fig. 2 is the electron micrograph picture on surface that shows an embodiment of negative pole of the present invention.
Fig. 3 is the electron micrograph picture on surface that shows another embodiment of negative pole of the present invention.
Fig. 4 (a)-Fig. 4 (d) is the process chart of an example of the manufacture method of expression negative pole shown in Figure 1.
Fig. 5 (a) and Fig. 5 (b) are respectively the electron micrograph picture of expression with the cross section structure of the negative pole of the manufacturing of the method shown in Fig. 4 (a)-Fig. 4 (d).
Fig. 6 (a)-Fig. 6 (f) is another routine process chart of the manufacture method of expression negative pole of the present invention.
Fig. 7 (a)-Fig. 7 (e) is expression current collection another routine process chart with the formation method of superficial layer.
Fig. 8 is the schematic diagram of wanting portion that amplifies the 2nd embodiment that shows negative pole of the present invention.
Fig. 9 is the electron micrograph picture in the cross section of the negative pole that obtains in embodiment 2-1.
Figure 10 (a) and Figure 10 (b) are illustrated in the current collection that obtains among the embodiment 3-1 to use the sweep type electromicroscopic photograph picture of superficial layer to reach at the photo picture that sees through under the state of light.
Figure 11 (a) and Figure 11 (b) are respectively the curve charts of the charge characteristic of the charge characteristic of photons that the negative pole that just obtains in embodiment 3-1 of expression is measured, that peeled off from foils and the plating side that is covered.
Figure 12 is expression about the curve chart of the relation of the charge and discharge cycles number of the electrode that obtains in embodiment 2-1 and comparative example 2-1 and 2-2 and discharge capacity.
Embodiment
Below based on its embodiment preferred negative electrode for nonaqueous secondary battery of the present invention is described.Fig. 1 expresses the schematic diagram of wanting portion of the 1st embodiment of having amplified negative pole of the present invention.In Fig. 1, only express a side's of negative pole face side, the opposing party's face side does not demonstrate, and the structure of side is also roughly same but then.
The negative pole 10 of the present embodiment, have as with table that nonaqueous electrolytic solution contacts in the 1st 1 and the 2nd of an opposite (not shown go out).Negative pole 10 possesses the active material layer 3 of the high active material particle 2 of the formation ability that contains lithium compound between the two sides.Active material layer 3 is formed at a pair of current collection of each face of this layer 3 respectively with superficial layer (side current collection with superficial layer not shown go out) 4 lining continuously.Each superficial layer 4 contains the 1st 1 and the 2nd respectively.In addition, as clear and definite by Fig. 1, negative pole 10 does not have the thick-film conductor body (for example metal forming) that the current collection that is called as collector body that uses is used in negative pole in the past, routine patent documentation 1 as previously discussed and 2 negative poles of being put down in writing.
Current collection is undertaken the current collection function in the negative pole 2 of the present embodiment with superficial layer 4.In addition, superficial layer 4 is used to also to prevent that active material layer 3 contained active materials from resulting from the expansion of embedding/this active material that the removal lithium embedded ion causes and shrinking and come off.Superficial layer 3 is made of the metal of the collector body that can become nonaqueous electrolytic solution secondary battery.Especially preferably the metal by the collector body that can become lithium secondary battery constitutes.As such metal, for example list the low metal material of formation ability of lithium compound.Enumerate the alloy of copper, nickel, iron, cobalt or these metals etc. particularly.Among these metals, especially preferably use copper and nickel or their alloy.Consider from the viewpoint of the intensity that improves electrode 10, preferably use nickel.In addition, consider, preferably use copper from the flexible viewpoint that improves negative pole 10.The constituent material of 2 superficial layers can be identical, perhaps also can be different.So-called " the formation ability of lithium compound is low " means: also be trace or very unstable even do not form intermetallic compound or solid solution with lithium or form lithium.
Each superficial layer 4 is thin layers of thick-film conductor body that its thickness is used than the current collection that uses in the electrode in the past.Specifically, be preferably about 0.3-10 μ m, the thin layer about 1-5 μ m particularly.In view of the above, can be with the necessary minimal thickness active material layer 3 that roughly fully and continuously is covered.Its result can prevent coming off of active material particle 2.In addition, by making the thin layer of this degree, and do not have the thick-film conductor body that current collection is used, the ratio that active material accounts for negative pole integral body relatively uprises, and can improve the energy density of every monomer volume and per unit weight.In negative pole in the past, because the thick-film conductor body that current collection is used accounts for the ratio height of negative pole integral body, therefore improving energy density has certain limit.The thin list surface layer 4 of above-mentioned scope is preferred as described later to be formed by electroplating.In addition, the thickness of 2 superficial layers 4 can be identical, perhaps can be different.
As previously discussed such, 2 superficial layers 4 contain the 1st 1 and the 2nd respectively.These faces constitute the outermost of the electrode of the present embodiment.The negative pole 10 of the present embodiment is assembled into the occasion in the battery, and the 1st and the 2nd face become the face that contacts with electrolyte, participates in electrode reaction.In contrast, the thick-film conductor body that the current collection in the negative pole is in the past used is in the occasion of its two sides formation active material layer, can not contact, not participate in electrode reaction, in addition with electrolyte, even in the occasion that simultaneously forms active material layer, only a side face contacts electrolyte.That is to say, do not exist in the thick-film conductor body that the current collection that uses in the negative pole is in the past used in the negative pole 10 of the present embodiment, be positioned at the outmost layer of negative pole, when being superficial layer 4 participation electrode reactions, having the current collection function concurrently and prevent the function that active material comes off.
Contain each superficial layer 4 of the 1st 1 and the 2nd respectively because the current collection function is all arranged, therefore be assembled into occasion in the battery, have the lead-in wire that electric current can be taken out usefulness and be connected to this advantage on any superficial layer 4 at negative pole 10 with the present embodiment.
As shown in Figure 1, negative pole 10 has at the 1st 1 and the 2nd perforate and a large amount of fine pore 5 of communicating with active material layer 3.Fine pore 5 is present in this superficial layer 4, and makes to the thickness direction extension of each current collection with superficial layer 4.By forming fine pore 5, nonaqueous electrolytic solution can fully soak into to active material layer 3, fully causes the reaction with the particle 2 of active material.Fine pore 5 is the fine holes about its wide about 10 μ m of about 0.1 μ m-of being in the occasion of cross-section superficial layer 4.Though fine pore 5 is fine, fine pore has the wide of degree that nonaqueous electrolytic solution can soak into.Especially nonaqueous electrolytic solution and aqueous electrolyte ratio, surface tension is little, even therefore the wide little of fine pore 5 also can fully be soaked into.Fine pore 5 can enough all methods described later form.Preferably when adopting plating to form superficial layer 4, side by side form.
During by the 1st 1 and the 2nd of electron microscope observation (overlooking), the average perforated area of the fine pore 5 at least one side's the face is 0.1-100 μ m preferably 2, be more preferably 0.1-50 μ m 2, further 0.1-20 μ m preferably 2, most preferably be 0.5-10 μ m 2About.By being defined as the perforated area of this scope, can guarantee that nonaqueous electrolytic solution fully soaks into, prevent coming off of active material particle 2 simultaneously effectively.In addition, just can improve charge/discharge capacity from the initial stage that discharges and recharges.From more effectively preventing the viewpoint that comes off of active material particle 2, above-mentioned average perforated area is the 0.1-50% of the maximum secting area of active material particle 2 preferably, is preferably 0.1-20% especially.The maximum secting area of active material particle 2 is meant the particle diameter (D that measures active material particle 2 50Value), this particle 2 regarded as have D 50Maximum secting area during the ball of diameter of value.
When average perforated area satisfies the face of above-mentioned scope among the 1st 1 and the 2nd of the electron microscope observation (overlooking), the summation of the perforated area of fine pore 5 is 0.1-20% with respect to the ratio (this ratio is called percent opening) of the area of field of view, preferably 0.5-10%.Its reason is to be defined as reason same in the above-mentioned scope with perforated area with fine pore 5.And according to same reason, when average perforated area satisfies the face of above-mentioned scope among the 1st 1 and the 2nd of the electron microscope observation (overlooking), even preferably take what kind of field of view, all there are 1-20,000, special preferably 10-1,000,50-500 fine pore 5 (this value is called distributive law) especially preferably within sweep of the eye in that 100 μ m * 100 μ m are foursquare.Express among Fig. 2 with the surface of an example of electron microscope observation negative pole of the present invention and the photo of taking.In Fig. 2, black fleck is the perforate of fine pore 5.Fig. 2 is that the object of observation is taken with the negative pole of making according to embodiment 1 described later.In addition, express among Fig. 3 with the surface of other examples of electron microscope observation negative pole of the present invention and the photo of taking.
According to Fig. 2 and shown in Figure 3, can confirm to have or not fine pore 5 by electron microscope observation.Fine pore 5 is because it is wide minimum, though therefore according to circumstances sometimes electron microscope observation can not judge clearly that it has or not existence.Under such situation, have or not the method for fine pore 5 as judgement, the present invention adopts in the following method.The negative pole that use becomes the judgement object that has or not fine pore 5 constitutes battery, once discharges and recharges.After that, with electron microscope observation negative pole cross section, cross section structure with discharge and recharge before than the occasion that changes, be judged as to discharge and recharge in the preceding negative pole and formed fine pore 5.Cross section structure with discharge and recharge before than the reason that changes be because of: by the fine pore 5 that exists in the negative pole before discharging and recharging, nonaqueous electrolytic solution arrives active material layer 3, takes place due to the result of reaction of lithium ion in the nonaqueous electrolytic solution and active material particle 2.
Be positioned at the high active material particle 2 of formation ability that active material layer 3 between the 1st 1 and the 2nd contains lithium compound.As this active material, for example list silicon based material or tin based material, aluminium based material, germanium based material.Active material layer 3 is because by 4 linings of 2 superficial layers, prevented from effectively therefore that active material from resulting to embed and removal lithium embedded ion and coming off.Active material particle 2 can contact with electrolyte by fine pore 5, therefore also can the hindrance electrode reaction.
The maximum particle diameter of active material particle 2 is 50 μ m or following preferably, are more preferably 20 μ m or following.In addition, use D 50During the particle diameter of value representation particle 2, be preferably 0.1-8 μ m, be preferably 1-5 μ m especially.When maximum particle diameter surpasses 50 μ m, easily cause coming off of particle 2, cause the lifetime of electrode.The lower limit of particle diameter is not particularly limited, and is more little preferred more.In view of the manufacture method of particle 2, lower limit is about 0.01 μ m.The particle diameter of particle 2 is measured by micro-tracking, electron microscope observation (SEM observation).
When active material is very few with respect to the amount of negative pole integral body, be difficult to fully improve the energy density of battery, served as on the contrary for a long time, exist easily to cause the tendency that active material comes off.Consider these, the amount of active material is preferably 5-80 weight % with respect to negative pole integral body, more preferably 10-50 weight %, more preferably 20-50 weight %.
The thickness of active material layer 3 can in the present embodiment, not limit especially corresponding to active material with respect to the ratio of the amount of negative pole integral body and suitable adjusting of particle diameter of active material.Be generally 1-100 μ m, be preferably especially about 3-40 μ m.Active material layer 3 as described later, preferably the conductivity paste that contains active material particle 2 by coating forms.
Consider to improve negative pole intensity and energy density, the thickness that contains the negative pole integral body of superficial layer 4 and active material layer 3 is preferably 2-50 μ m, is preferably especially about 10-50 μ m.
In active material layer 3, preferred formation contains the material of each superficial layer 4 of the 1st 1 and the 2nd respectively, is impregnated into the whole zone of thickness direction of active material layer 3.And preferably in this material that soaks into, there is active material particle 2.That is to say that preferred active material particle 2 is not exposed to the surface of negative pole 10 in fact, but is embedded in the inside of superficial layer 4.In view of the above, the adhesiveness of active material layer 3 and superficial layer 4 becomes firmly, has prevented that more active material from coming off.In addition, by being impregnated into the above-mentioned material in the active material layer 3, between superficial layer 4 and active material, guarantee electronic conductivity, therefore prevented from effectively to generate, particularly prevented from effectively to generate active material isolated on the electricity, kept the current collection function in the deep of active material layer 3 at active material isolated on the electricity.Its result has suppressed to reduce as the function of negative pole.And then also can seek the long lifetime of negative pole.This situation use the material that lacks as semi-conductive electronic conductivity for example the silicon based material as the occasion advantageous particularly of active material.Can know clearly thus, the negative pole of the present embodiment, its structure is and makes the electrode in the past that supports active material particle in the metal foam body and this foams two sides enforcement plating is constituted diverse.In having used the electrode in the past of such metal foam body, the fully tight contact active material particle of skeleton structure of metal foam body is not easy, therefore be difficult to improve electronic conductivity, fully effectively utilize the performance of active material to be not easy.
Constitute the thickness direction of current collection, and be connected with two superficial layers 4 with the preferred osmo active substance layer 3 of material of superficial layer 4.In view of the above, 2 superficial layers 4 conduct by above-mentioned material, and the electronic conductivity as negative pole integral body uprises more thus.That is to say, the negative pole 10 of the present embodiment, whole negative pole becomes one and has the current collection function.Thereby constitute current collection is impregnated into active material layer with the material of superficial layer 4 thickness direction whole zone two superficial layers situation connected to one another by being that the electron microscope of determination object is surveyed and drawn and can be tried to achieve with this material.Make and constitute current collection and narrate in the back with the method for optimizing that the material of superficial layer 4 is impregnated in the active material layer.
Be full of fully between the active material particle 2 in the active material layer 3 and without the constituent material of superficial layer 4, preferably between this particle, have hole 6 (should be careful this hole be be formed at current collection different) with the fine pore 5 of superficial layer 4.By there being this hole 6, thereby resulting from active material particle 2 embeddings and the removal lithium embedded stress that shrinks that expands is relaxed.From this viewpoint, the ratio of the hole 6 in the active material layer 3 is preferably about 5-30 volume %, especially preferably about 5-9 volume %.The ratio of hole 6 can be followed the tracks of by electron microscope and be obtained.As described later, active material layer 3 contains the conductivity paste and dry formation of active material particle 2 by coating, so forms hole 6 in active material layer 3 naturally.Therefore, for the ratio that makes hole 6 in above-mentioned scope, the suitable selection for example particle diameter, the composition of conductivity paste, the coating condition of paste of active material particle 2 gets final product.In addition, also can be with behind the dry formation of the paste coating active material layer 3, press process under suitable condition, the ratio of adjustment hole 6.
The particle 7 that preferably in active material layer 3, except containing active material particle 2, also contains conductive carbon material or conductive metal material.In view of the above, further anticathode 10 is given electronic conductivity.From this viewpoint, the amount of the particle 7 of contained conductive carbon material or conductive metal material is preferably 0.1-20 weight %, is preferably 1-10 weight % especially in the active material layer 3.For example use the particle of acetylene black and graphite etc. as conductive carbon material.Consider from the viewpoint of further giving electronic conductivity, the particle diameter of these particles be preferably 40 μ m or following, be preferably 20 μ m or following especially.The particle diameter lower limit of this particle is not particularly limited, and is more little preferred more.In view of the manufacture method of this particle, its lower limit is about 0.01 μ m.
The following describes the details of active material.Use the silicon based material of previous narration or the occasion of tin based material as active material, particle as this silicon based material or tin based material for example lists: the particle of (1) elementary silicon or tin simple substance, (2) are the compound particles, the particle that forms at the particle surface coated metal of elementary silicon or tin simple substance with the stuff and other stuff of metallic, (6) etc. of compound particles, (5) silicon or the tin and the metal of stuff and other stuff, (4) silicon or the tin and the metal of stuff and other stuff, (3) silicon or the tin and the metal of silicon or tin and carbon at least.When using the particle of (2), (3), (4), (5) and (6), the situation ratio with the particle of elementary silicon that uses (1) or tin simple substance has and has suppressed to result from the embedding of lithium and this advantage of micronizing of taking off the silicon based material of embedding more.In addition, can give electronic conductivity this advantage to the silicon that lacks as semi-conductive electronic conductivity in addition.
Be particle or the tin occasion that to be particle be made of the stuff and other stuff of the silicon at least of (2) or tin and carbon at silicon particularly, when cycle life improved, capacity of negative plates increased.It is the reasons are as follows.Carbon, the graphite that particularly uses in negative electrode for nonaqueous secondary battery have following characteristics: help the embedding of lithium and take off embedding, have the capacity of negative plates about 300mAh/g, and the volumetric expansion of lithium when embedding is very little.On the other hand, silicon has following characteristics: have the capacity of negative plates about 10 times of graphite or above 4200Ah/g.Volumetric expansion when the lithium of reverse side silicon embeds reaches about 4 times of graphite.So, when the carbon of pulverizing silicon or tin and graphite and so on the mixing such as ratio use Mechanical Method of regulation, when making particle diameter for the powder of the homogeneous of about 0.1-1 μ m mixing, silicon when lithium embeds or the volumetric expansion of tin are relaxed by graphite, cycle life improves, in addition, obtain capacity of negative plates about 1000-3000mAh/g.The blending ratio of silicon or tin and carbon, the amount of preferred silicon or tin be 10-90 weight %, especially be preferably 30-70 weight %, especially be preferably 30-50 weight %.On the other hand, the amount of carbon be preferably 90-10 weight %, especially be preferably 70-30 weight %, especially be preferably 70-50 weight %.If form in this scope, then can seek the high capacity of battery and the long lifetime of negative pole.In this stuff and other stuff, do not form compounds such as carborundum.
Silicon is particle or the tin occasion that to be particle be made of the particle of (2), and this particle also can also contain the stuff and other stuff of other metallic elements, 3 kinds or more kinds of element outside silicon or tin and carbon.As metallic element, can list a kind or more kinds of elements (following these elements are generically and collectively referred to as added metal) being selected among Cu, Ag, Li, Ni, Co, Fe, Cr, Zn, B, Al, Ge, Sn, In, V, Ti, Y, Zr, Nb, Ta, W, La, Ce, Pr, Pd and the Nd.
At silicon is that particle or tin are that particle is the occasion of the stuff and other stuff of the silicon of (3) or tin and metal, as the metal that in this stuff and other stuff, contains, can list a kind of above-mentioned interpolation metal, two or more.These add among the metal, and preferred Cu, Ag, Ni, Co, Ce particularly from the low viewpoint of the formation ability of electronic conductivity excellence and lithium compound, wish to use Cu, Ag, Ni.In addition, if use Li as adding metal, then contain lithium metal in advance in active material, so the advantage that has that efficiency for charge-discharge improves and reduced the cycle life raising that brings etc. by volume change is preferably.In the stuff and other stuff of the silicon of (3) or tin and metal, the amount of silicon or tin be preferably 30-99.9 weight %, especially be preferably 50-95 weight %, especially be preferably 85-95 weight %.On the other hand, the amount of adding metal be preferably 0.1-70 weight %, especially be preferably 5-50 weight %, especially be preferably 5-15 weight %.If form in this scope, then can seek the high capacity of battery and the long lifetime of negative pole.
The for example available following method manufacturing of the stuff and other stuff of silicon (3) or tin and metal.At first, mix the metallic of silicon particle or tin particle and interpolation metal, adopt pulverizer to carry out the mixing and the pulverizing of these particles simultaneously.As pulverizer, can use vertical ball mill, aeropulverizer, cyclone type grinding machine, coating shaking machine, fine mill (fine mill) etc.The particle diameter of these particles before pulverizing is preferably about 20-500 μ m.By the mixing and the pulverizing of pulverizer, obtain silicon or tin and the mixed uniformly particle of interpolation metal.It for example is 40 μ m or following that operating condition by suitable control pulverizer makes the particle diameter of particle.Obtain the stuff and other stuff of (3) in view of the above.
Silicon is that particle or tin are that particle is the occasion of the compound particles of the silicon of (4) or tin and metal, this compound comprises the alloy of silicon or tin and metal, is 1) solid solution, 2 of silicon or tin and metal) intermetallic compound or 3 of silicon or tin and metal) and by silicon single-phase or tin is single-phase, wantonly a kind of the complex of the two-phase among the intermetallic compound of solid solution, silicon or the tin of metal single phase, silicon or tin and metal and metal or above phase composition.As above-mentioned metal, can use the contained same metal of interpolation metal in the stuff and other stuff with the silicon of (3) or tin and metal.The composition of silicon in the compound particles (4) or tin and metal, same with the stuff and other stuff of (3), the amount of preferred silicon or tin is 30-99.9 weight %, the amount of metal is 0.1-70 weight %.Preferred composition is selected suitable scope according to the manufacture method of compound particles.For example this compound is the bianry alloy of silicon or tin and metal, uses quench described later to make the occasion of this alloy, and the amount of wishing silicon or tin is 40-90 weight %.On the other hand, the amount of preferably adding metal is 10-60 weight %.
At above-claimed cpd is the ternary of silicon or tin and metal or the occasion of more polynary alloy, also further contains the element that is selected among B, Al, Ni, Co, Sn, Fe, Cr, Zn, In, V, Y, Zr, Nb, Ta, W, La, Ce, Pr, Pd and the Nd in the bianry alloy that can formerly narrate on a small quantity.Obtain to suppress this additional effect of micronizing in view of the above.In order to improve this effect more, these elements preferably contain 0.01-10 weight %, especially preferably contain 0.05-1.0 weight % in the alloy of silicon or tin and metal.
The compound particles of silicon (4) or tin and metal is the occasion of alloy particle, when this alloy particle adopts the quench of for example following explanation to make, the crystallite of alloy becomes fine size, and homogeneous disperses, micronizing is suppressed thus, considers preferred this quench manufacturing of adopting from the aspect that keeps electronic conductivity.In this quench, at first prepare to contain silicon or tin, with the fused solution of the raw material that adds metal.Raw material forms fused solution by the high frequency fusing.The scale of silicon in the fused solution or tin and interpolation metal is decided to be aforesaid scope.Consider and the relation of chilling condition that the temperature of fused solution is preferably 1200-1500 ℃, is preferably 1300-1450 ℃ especially.Use the mold casting to obtain alloy by this fused solution.That is, this fused solution is poured into copper or mold made of iron, obtaining by the Si system alloy of chilling or tin is the ingot casting of alloy.This ingot casting is pulverized and screening, will for example be that particle diameter 40 μ m or following particle are used for the present invention.
Also can replace this mold casting to use the roller casting.That is, the periphery of fused solution to the roller made of copper of high speed rotating penetrated.The velocity of rotation of roller considers that from the viewpoint that makes the fused solution chilling preferred rotating speed is 500-4000rpm, is preferably 1000-2000rpm especially.Occasion represent the velocity of rotation of roller with peripheral speed is preferably 8-70m/ second, is preferably 15-30m/ second especially.By the fused solution of use with the temperature of the above-mentioned scope of roller chilling of the speed rotation of above-mentioned scope, cooling rate reaches 10 2K/ second or above, particularly 10 3K/ second or above high speed.Emitted fused solution is become thin slice by chilling on roller.This thin slice is pulverized, sieved, for example particle diameter 40 μ m or following particle are used for the present invention.Replace this quench, the using gases atomization inert gases such as argon of in 1200-1500 ℃ fused solution, jetting with the atmospheric pressure of 5-100, micronize and chilling also can obtain desired particle.In addition, as method for distinguishing, also can use arc-melting method or Mechanical Method.
Active material particle be the silicon of (5) or tin and metal compound particles, with the occasion of the stuff and other stuff of metallic, can use the same particle of compound particles with (4) of previous narration as this compound particles.On the other hand, as the particle of metal, can use the identical particle of metallic that uses in the stuff and other stuff with (3) of previous narration.In the compound particles contained metallic element and the metallic element that constitutes metallic can be of the same race also can be not of the same race.Particularly contained metallic element is nickel, copper, silver or iron in the compound particles, when the metallic element that constitutes metallic is nickel, copper, silver or iron, easily forms the network configuration of these metals in active material layer.Its result, electron gain conductibility improve, prevent to be shunk by the expansion of active material particle the advantageous effects of coming off of causing etc., so preferably.Consider that from this viewpoint metallic element contained in the preferred compound particle is of the same race with the metallic element that constitutes metallic.(5) active material particle, adopt with the same method of the manufacture method of the compound particles of (4) of previous narration and at first obtain compound particles, then by mixing this compound particles according to the manufacture method of the stuff and other stuff of (3) of previous narration and metallic obtains.The ratio of silicon in the compound particles or tin and metal can be identical with both ratio in the compound particles of (4) of previous narration.In addition, the ratio of compound particles and metallic can be identical with the ratio of the particle of silicon in the stuff and other stuff of (3) of previous narration or tin and metallic.Beyond these, about the aspect that the active material particle of (5) does not specify, the explanation that the suitable compound particles that is suitable for about the stuff and other stuff of (3) of previous narration or (4) describes in detail.
Silicon is that particle or tin are that particle is the occasion of the particle (this particle is called the coating metal particle) that forms of the particle surface coated metal at elementary silicon or tin simple substance of (6), as coated metal, use identical metals (wherein except the Li) such as interpolation metal contained in the particle with (3) or (4) before narrated, for example copper.The silicon in the coating metal particle or the amount of tin are preferably 70-99.9 weight %, are preferably 80-99 weight % especially, especially are preferably 85-95 weight %.On the other hand, be preferably 0.1-30 weight %, be preferably 1-20 weight % especially, especially be preferably 5-15 weight % with the amount of the coated metal headed by the copper.The coating metal particle for example uses electroless plating (or being called chemical plating) manufactured.In this electroless plating method, at first prepare suspension silicon particle or tin particle and contain electroplating bath with the coated metal headed by the copper.In this electroplating bath, electroless plating silicon particle or tin particle make the surface-coated above-mentioned coated metal of this silicon particle or tin particle.The silicon particle in the electroplating bath or the concentration of tin particle are preferably about 400-600g/l.As the occasion of above-mentioned coated metal, preferably make and contain copper sulphate, Rochelle salt etc. in the electroplating bath at electroless plating copper.Consider that from the aspect of control plating speed the concentration of preferably sulfuric acid copper is that the concentration of 6-9g/l, Rochelle salt is 70-90g/l under this situation.Because same reason, the pH of preferred electroplating bath is 12-13, and bathing temperature is 20-30 ℃.As the reducing agent that in electroplating bath, contains, for example use formaldehyde etc., its concentration can be defined as 15-30cc/l.
At active material particle 7 are occasions of siliceous particle, and no matter this siliceous particle is which kind of form among above-mentioned (1)-(5), all preferred its average grain diameter (D 50) be 0.1-10 μ m, especially preferably 0.3-8 μ m, especially preferably 0.8-5 μ m.That is to say that this active material particle is the minuteness particle (following this active material particle is called the small-particle diameter active material particle) of small particle diameter.By using the small-particle diameter active material particle, be difficult for more causing that active material particle comes off from negative pole, the long lifetime of the negative pole possibility that becomes.More particularly, active material particle is owing to be attended by significant change in volume, therefore little by little controlled micro crystallization or micronizing when lithium is emitted in embedding.Result from that crackle takes place for this, lost the electrochemistry contact of a part of active material particle.This becomes the principal element as " charge " reduction of the important characteristic of secondary cell.So by from just used the minuteness particle of small particle diameter originally negative pole, the further micronizing of the particle when suppressing to discharge and recharge improves charge.The average grain diameter of small-particle diameter active material particle easily causes the oxidation of particle during less than the lower limit of above-mentioned scope.In addition, such minuteness particle manufacturing cost uprises.The particle diameter of small-particle diameter active material particle is measured by laser diffraction and scattering method, electron microscope observation (SEM observation).
The small-particle diameter active material particle is because its surface area is big, and is therefore with particle (for example tens microns the particle) ratio of bigger particle diameter, easily oxidized.The principal element that be oxidized into the active material particle principal element that similarly increases for " irreversible capacity " of secondary cell key property with " charge " and " charging and discharging currents efficient " reduce.Specifically, when volume ground contained aerobic in the small-particle diameter active material particle, the lithium ion that is embedded by electrochemistry formed firm combining with oxygen atom, and lithium ion is not dissociated when discharge.Therefore, the small-particle diameter active material particle needs the particle of bigger particle diameter more strictly to manage oxygen concentration.Specifically, the concentration of the oxygen that the small-particle diameter active material particle contains is preferably less than 2.5 weight %, more preferably 1.5 weight % or following, more preferably 1 weight % or following.To this, therefore the particle of bigger particle diameter does not need strictness like that for oxidation because surface area is little.The concentration of the oxygen that contains in the small-particle diameter active material particle is low more preferred more.Much less, complete oxygen-free most preferably, but in view of the manufacture method of small-particle diameter active material particle, the minimum of the oxygen concentration that can reach is about 0.005 weight % now.The oxygen concentration of small-particle diameter active material particle is measured by the eudiometry with the burning of determination object sample.
On the basis of the oxygen concentration that in small-particle diameter active material integral body, contains less than above-mentioned value, this small-particle diameter active material particle is preferably above 1/2 of oxygen concentration in the concentration of the most surperficial Si of particle, more preferably 4/5 or more than, more preferably 10 or more than.The inventor's result of study shows that the reduction of the increase of irreversible capacity and charging and discharging currents efficient is mainly by about the most surperficial oxygen concentration of small-particle diameter active material particle.Its reason be because, be present in the most surperficial oxygen when secondary cell charge easily with the lithium reaction, become the reason that makes the battery behavior degeneration.So, stipulate the ratio of the concentration of the concentration of the most surperficial Si of particle and oxygen as described above.The surface oxygen concentration of small-particle diameter active material particle adopts and measures with the various surface state analytical equipments headed by X-ray photoelectron spectroscopic analysis device (ESCA) and the Auger electron spectroscopy analytical equipment (AES) etc.
State in the use (1)-occasion of any method of (5) under, all preferred small-particle diameter active material particle of under the condition of not sneaking into oxygen, for example inert gas atmosphere, making.
Even the small-particle diameter active material particle is any of above-mentioned (1)-(5), this small-particle diameter active material particle adopts the breaking method of regulation all to be ground into the average grain diameter of above-mentioned scope.As breaking method, representational have dry type comminuting method and a case of wet attrition method.In the dry type comminuting method, for example use aeropulverizer etc.On the other hand, in the case of wet attrition method, particle is dispersed in has used in the pulverizing solvent of hexane and acetone and other organic solvent, use crushing medium sized particles such as alumina beads and zirconia bead.
By this crushing operation, the small-particle diameter active material particle is oxidized under the situation mostly.So, preferably, with small-particle diameter active material particle (the average grain diameter D of this particle behind the crushing operation 50Be 0.1-10 μ m) use the corrosive liquid corrosion, remove the oxide that is present in this particle surface.In view of the above, can easily make the most surperficial oxygen concentration of the oxygen concentration of small-particle diameter active material integral body and particle smaller or equal to aforesaid value.For example list HF, buffering acid, NH as corrosive liquid 4The aqueous solution of F, KOH, NaOH, ammonia or hydrazine etc.The degree of corrosion can be according to suitable controls such as the temperature of the kind of corrosive liquid and concentration, corrosive liquid, etching times.In view of the above, can easily make the most surperficial oxygen concentration of the oxygen concentration of small-particle diameter active material integral body and particle in above-mentioned scope.But, in this operation, should not remove the oxide of particle surface fully.Its reason be because, the particle of having removed oxide fully in being exposed to atmosphere the time by oxidation sharp.Therefore, in this operation, the preferred degree of adjusting corrosion makes that the oxide appropriateness is residual.Surface appropriateness residual the particle of oxide, even also can keep the surface and the whole oxygen concentration of this particle after the corrosion after in being exposed to atmosphere substantially.
For example, with the occasion of HF corrosion, in being HF about 1-50 weight %, concentration drops into the small-particle diameter active material particle, by about 5-30 minute, making the most surperficial oxygen concentration of particle be reduced to desired level at stirring at room liquid.In occasion, in being the aqueous solution about 1-40 weight %, concentration drops into the small-particle diameter active material particle, by getting final product about 5-120 minute at stirring at room liquid with KOH or NaOH corrosion.In occasion with ammonia corrosion, drop into the small-particle diameter active material particle in the aqueous solution about concentration 1-20 weight %, get final product about 5-60 minute at stirring at room liquid.Using NH 4The occasion of F corrosion drops into the small-particle diameter active material particle in the aqueous solution about concentration 1-50 weight %, get final product about 5-60 minute at stirring at room liquid.In occasion with the hydrazine corrosion, drop into the small-particle diameter active material particle in the aqueous solution about concentration 1-50 weight %, get final product about 5-60 minute at stirring at room liquid.
The negative pole that contains the small-particle diameter active material particle of above explanation, even repeated charge, the micronized influence of the miniaturization of active material particle is also little.Consequently, efficiency for charge-discharge is enhanced, and irreversible capacity reduces the charge raising.In addition, by reducing the oxygen content in the small-particle diameter active material particle, irreversible capacity also reduces, and efficiency for charge-discharge improves the charge raising.
The surface of small-particle diameter active material particle also can be covered with metallic film.When adopting the metallic film lining, the oxidation of small-particle diameter active material particle is suppressed, and has prevented that effectively irreversible capacity from increasing and charging and discharging currents efficient reduces.In addition, electronic conductivity also improves, and charge is further improved.
The viewpoint that reaches the reaction of carrying out Li and Si expeditiously from the viewpoint that suppresses the oxidation of small-particle diameter active material particle effectively considers that the thickness of metallic film is preferably 0.005-4 μ m, is preferably 0.05-0.5 μ m especially.The thickness of metallic film is for example measured by ESCA or AES.
As the metal that constitutes metallic film, preferably use lithium to form the low metal of ability.As such metal, for example use Ni, Cu, Co, Fe, Ag or Au, particularly from anti-oxidation viewpoint, preferably use Ni, Co, Ag, Au.The form of the alloy that these metals can be respectively use or form with the metallic combination by two or more with simple substance is used.
In small-particle diameter active material particle with the metallic film lining, the oxygen concentration of the boundary portion of metallic film and small-particle diameter active material particle, as describing about above-mentioned small-particle diameter active material particle, the concentration of Si reaches above 1/2 of oxygen concentration.The boundary portion of metallic film and small-particle diameter active material particle is considered to, and analyzes the small-particle diameter active material particle that is covered with metallic film by AES, and the metal concentration that constitutes metallic film reaches minimizing part.
From improving the aspect with the conductivity of the small-particle diameter active material particle of metallic film lining, the most surperficial oxygen concentration of preferable alloy film is low.
Small-particle diameter active material particle with the metallic film lining is preferably made in the following method.At first, according to the manufacture method of previously described small-particle diameter active material particle, after employing dry type comminuting method or case of wet attrition method are ground into the size of regulation with particle, by the oxide of this particle surface existence of erosion removal.Fully the particle after the washing corrosion then, is committed to the electroless plating operation, at particle surface coated metal film.Also can before electroless plating, implement common sensitization processing and activation processing to particle surface.The condition of electroless plating is suitably selected according to the metal of plating is suitable.For example form, can list following bath and form as the bath of the occasion of plating Ni.Under this situation, bathe temperature and be decided to be about 40-60 ℃, the pH of bath is decided to be about 4-6.The plating time is decided to be the 0.5-50 branch.
·NiSO 4·6H 2O???15-35g/l
·NaH 2PO 4·H 2O?10-30g/l
·Na 3C 6H 5O 7???15-35g/l
·NaC 3H 5O 2?????5-15g/l
The metallic film that forms on small-particle diameter active material surface is incomplete coated particle integral body also.For example, this metallic film also can be roughly coated particle surface equably and fully, and make a large amount of fine pore that extends in the thickness of metal film direction be present in this metallic film.Arrive the inside of small-particle diameter active material particle in view of the above by fine pore electrolyte, therefore the original electrochemical reaction that shows of siliceous particle can take place effectively.Perhaps, metallic film also can island ground coated particle.
Below with reference to Fig. 4 (a)-Fig. 4 (d) the 1st preferable production process of the negative pole of the present embodiment is described.At first shown in Fig. 4 (a), prepare foils 11.Material to foils 11 is not particularly limited.Preferred vector paper tinsel 11 is a conductivity.In this case, if conductivity is arranged, then foils 11 can not be a metallic also., by using metal foils 11, foils 11 is dissolved the advantage that foliations can utilize again thereby have after making electrode 10.Consider the easiness of utilization again, the material of the foils 11 preferably material with the superficial layer 4 that forms by plating described later is identical.Foils 11 is owing to be that supporter as the negative pole 10 that is used to make the present embodiment uses, and therefore preferably has the intensity that wrinkling (bunch up) etc. do not take place in manufacturing process.Therefore the thickness of foils 11 is preferably about 10-50 μ m.
Foils 11 for example can adopt electrolysis or rolling manufacturing.By adopting rolling manufacturing, can access the low foils of surface roughness 11.By using the low foils 11 of surface roughness, has the advantage that also can not form peel ply 11a described later.On the other hand, make foils 11, can onlinely carry out from the manufacturing that is fabricated onto negative pole 10 of foils 11 by adopting electrolysis.Online carrying out considers it is favourable from the stable manufacturing of negative pole 10 and the reduction aspect of manufacturing cost.Adopting electrolysis to make the occasion of foils 11, using rotary drum, in the electrobath of the metal ion that contains copper and mickel etc., carrying out electrolysis, making metal separate out (promptly depositing) at the side face of drum as negative electrode.Obtain foils 11 by peeling off the metal of separating out from the drum side face.
In the low occasion of the surface roughness of foils 11, can on foils 11 surfaces, directly form active material layer 3.In addition, shown in Fig. 4 (a), also can form peel ply 11a, on this peel ply, form active material layer 3 in the one side of foils 11.By forming peel ply 11a, can more successfully peel off.In addition, the advantage that can give rust-proof effect to foils 11 is also arranged.No matter whether form peel ply 11a, all the surface roughness Ra of preferred vector paper tinsel 11 is 0.01-3 μ m, is preferably 0.01-1 μ m especially, especially is preferably 0.01-0.2 μ m.If the low surface roughness of this degree then can successfully be peeled off.In addition, the occasion forming peel ply 11a can form the peel ply 11a that does not have thickness irregular.Especially in the occasion that forms peel ply 11a, reduced the surface roughness of foils 11 by this peel ply 11a, even therefore also the surface roughness Ra of foils 11a is also passable greater than above-mentioned scope sometimes.
Peel ply 11a for example waits and forms by chromium plating, nickel plating, lead plating, chromate processing.In addition, also can adopt the spy to open the nitrogen-containing compound that the nitrogen-containing compound of record in paragraph [0037]-[0038] of flat 11-317574 communique or sulfur-containing compound, spy open record in paragraph [0020]-[0023] of 2001-140090 communique or the formation such as mixture of sulfur-containing compound and copper microfine.Wherein, consider, preferably adopt chromium plating, nickel plating, lead plating or chromate to handle and form peel ply 11a from the aspect that fissility is good.Its reason is because by the layer at peel ply 11a surface formation oxide or hydrochlorate such as these processing, this layer has reduction foils 11 and the adhesiveness of electrodeposited coating described later, the function of raising fissility.From the aspect that can successfully peel off, the thickness of peel ply 11a is preferably 0.05-3 μ m.Form the surface roughness Ra of this peel ply 11a behind the peel ply 11a, with on foils 11 directly the occasion of formation active material layer 3 similarly be preferably 0.01-3 μ m, be preferably 0.01-1 μ m especially, especially be preferably 0.01-0.2 μ m.
The foils 11 that adopts electrolysis to make results from its manufacture method, and one face is level and smooth glassy surface, and another face is an irregular not only sliding surface (frosted face).That is to say that the surface roughness of each face is different mutually.Glassy surface is that not only sliding surface is the face of separating out in the face of the face of the bulging side face in the electrolysis.In this manufacture method, on foils 11, form the occasion of peel ply 11a, also can on glassy surface and frosted face any, form peel ply 11a.Consider that fissility is good, preferably on the low glassy surface of surface roughness, form peel ply 11a.On frosted face, form the occasion of peel ply 11a, for example use and open the electrolysis additive of putting down in writing in the flat 9-143785 communique the spy and carry out electrolysis, use the paper tinsel of making like this, or before the formation of peel ply 11a, the frosted face corrosion is got final product.Perhaps adopt the surface roughness of rolling reduction frosted face to get final product.
Secondly, shown in Fig. 4 (b), coating contains the conductivity paste of active material particle on peel ply 11a, forms active material layer 3.In the occasion that does not form peel ply 11a, directly form active material layer 3 on foils 11 surfaces.Paste comprises particle, adhesive and the retarder thinner etc. of active material particle, conductive carbon material or conductive metal material.Among these compositions, use polyvinylidene fluoride (PVDF), polyethylene (PE), EPDM (EPDM) etc. as adhesive.As retarder thinner, use N-methyl pyrrolidone, cyclohexane etc.The amount of the active material particle in the paste is preferably about 14-40 weight %.The amount of the particle of conductive carbon material or conductive metal material is preferably about 0.4-4 weight %.The amount of adhesive is preferably about 0.4-4 weight %.In addition, the amount of retarder thinner is preferably about 60-85 weight %.
After the dried coating film of paste forms active material layer 3, the foils 11 that has formed this active material layer 3 is immersed in the electroplating bath of the low metal material of the formation ability that contains lithium compound, electroplates.By flooding in electroplating bath, plating bath is immersed in the active material layer 3, arrives the interface of active material layer 3 and peel ply 11a, electroplates under this state.Consequently, in the inside of (a) active material layer 3, the exterior side of (b) active material layer 3 (the face side that promptly contacts) and (c) inner face side of active material layer 3 (i.e. the face side of facing with peel ply 11a) with plating bath, the low metal material of formation ability of lithium compound is separated out, when forming each superficial layer 4, the material that constitutes superficial layer 4 is impregnated into the whole zone of thickness direction of active material layer 3, obtains the negative pole 10 (with reference to Fig. 4 (c)) of structure shown in Figure 1.
As the condition of electroplating, for example use the occasion of copper as the low metal material of the formation ability of lithium compound, when using copper sulphate to be solution, the concentration of copper is decided to be 30-100g/l, the concentration of sulfuric acid is decided to be 50-200g/l, the concentration of chlorine is decided to be 30ppm or following, the liquid temperature is decided to be 30-80 ℃, current density is decided to be 1-100A/dm 2Get final product.Using cupric pyrophosphate is the occasion of solution, and the concentration of copper is decided to be 2-50g/l, and the concentration of potassium pyrophosphate is decided to be 100-700g/l, and the liquid temperature is decided to be 30-60 ℃, and pH is decided to be 8-12, and current density is decided to be 1-10A/dm 2Get final product.By suitable these electrolytic conditions of regulating, the material that constitutes superficial layer 4 is impregnated into the whole zone of thickness direction of active material layer 3, thereby two superficial layers 4 conduct.And, in superficial layer 4, easily form previous a large amount of fine pore 5 of narrating.
By electroplating the method that on superficial layer 4, forms fine pore 5, form fine pore with employing press process described later and compare, be the method that does not apply external force, therefore have the advantage that superficial layer 4 and then negative pole 10 can not sustain damage.The inventor infers that the mechanism that forms fine pore 5 when forming superficial layer 4 is as follows.That is, because active material layer 3 is the layers that contain active material particle 2, so active material layer 3 surfaces are the concaveconvex shape of microcosmic.That is to say, become the state that easy active site of growing up of coating and the difficult point of growing up of coating mix existence.When the active material layer of such state was electroplated, the growth of coating produced irregular, grew up in the particle polycrystalline shape ground of the constituent material of superficial layer 4.Crystal growth is carried out, and adjacent crystal touching forms hole in this part.By inference, the hole of Xing Chenging connects in a large number like this, forms fine pore 5 thus.According to this method, fine pore 5 its structures are extremely fine.
Also can after forming electrode 10,, make superficial layer 4 that fine pore 5 take place with its press process.Consider from the viewpoint that obtains sufficient electronic conductivity, preferably carry out the densificationization of press process, make the thickness summation of active material layer 3 and superficial layer 4 after the press process reach 90% before the press process or below, preferably reach 80% or below.Press process can be used for example roll squeezer.As previously discussed like that, have the hole 6 of 5-30 volume % in the active material layer 3 after the preferred press process.Because the existence of this hole 6, when charging, embed the occasion of lithium volumetric expansion, the stress of this volumetric expansion of resulting from is relaxed.The condition that such hole 6 is controlled press process as described above like that gets final product.The value of this hole 6 is as previously discussed like that, can follow the tracks of by electron microscope and obtain.
In this manufacture method, also can be before electroplating, press process active material layer 3 (with the meaning of the press process of previous narration difference on this press process is called preceding press process).By carrying out preceding press process, prevented peeling off of active material layer 3 and superficial layer 4, prevented that also active material particle 2 from exposing on electrode 10 surfaces.Its result can prevent to result from the degeneration of the cycle life of the battery that active material particle 2 comes off.And, by carrying out preceding press process, can control the degree (with reference to embodiment described later) that the material that constitutes superficial layer 4 soaks in active material 3.Specifically, when the degree of suppressing was big, the distance that active material particle is 2 shortened, and the material that constitutes superficial layer 4 easily soaks in active material 3.As the condition of preceding press process, preferably such condition: the thickness of the active material layer 3 before the thickness of the active material 3 after the preceding press process reaches before the press process 95% or below, preferably reach 90% or below.
At last, shown in Fig. 4 (d), in the part of peel ply 11a from foils 11 peel separation electrodes 10.In Fig. 4 (d), depict peel ply 11a as and remain in foils 11 sides, but in fact peel ply 11a had both remained in foils 11 sides sometimes according to the kind of its thickness and stripping treatment agent, remained in electrode 10 sides again sometimes.Perhaps also remain in sometimes on these both sides.Therefore in any occasion, its thickness of peel ply 11a is had no effect to the performance of the negative pole that obtains all as thin as a wafer.Express the structure of an example of the negative pole of making according to this manufacture method among Fig. 5 (a) and Fig. 5 (b).Fig. 5 (a) compares with Fig. 5 (b), the particle diameter difference of the active material of use, and the particle diameter of the active material among Fig. 5 (b) is less than the particle diameter of the active material among Fig. 5 (a).
According to this manufacture method, the formation operation of only carrying out 1 active material layer 3 just obtains the two sides of electrode to be used for the negative pole 10 of electrode reaction.In negative pole in the past,, need form active material layer respectively with the two sides of thick-film conductor body at current collection for the two sides with electrode is used for electrode reaction.That is to say, need carry out the formation operation of 2 active material layers.Therefore, according to this manufacture method, the manufacturing efficient of negative pole very improves.
In addition, according to this manufacture method, by before being assembled into negative pole 10 in the battery, it not being peeled off from foils 11, but before being about to be assembled into, peel off from foils 11, thus can good operability the ground transportation thin and the easy negative pole 10 of the present embodiment of fold also has this advantage.
The limit is with reference to the 2nd preferable production process of Fig. 6 (a)-Fig. 6 (f) limit explanation negative pole.About this manufacture method, the not suitable explanation that is suitable for relevant the 1st manufacture method of the point of Te Bieshuominging.The point that the 2nd manufacture method is different with the 1st manufacture method is: in this manufacture method, before forming active material layer 3 on the foils 11, on foils 11, electroplate the low metal material of formation ability of lithium compound, form a current collection superficial layer 4a, at this current collection formation active material layer 3 on the superficial layer 4a, on active material layer 3, electroplate the low metal material of formation ability of lithium compound, form another current collection superficial layer 4b.
At first shown in Fig. 6 (a), prepare foils 11.Secondly, shown in Fig. 6 (b), form thin peel ply 11a in the one side of foils 11.In this manufacture method, also can on any one of glassy surface and frosted face, form peel ply 11a.
One has formed peel ply 11a, just shown in Fig. 6 (c), electroplates the low metal material of formation ability of lithium compound on peel ply, forms a superficial layer 4a.As the condition of electroplating, can use the condition identical with the plating in the 1st manufacture method.Can in superficial layer 4a, easily form the fine pore of previous narration by this plating.Then, shown in Fig. 6 (d), coating contains the conductivity paste of active material particle on superficial layer 4a, forms active material layer 3.The surface of the superficial layer 4a of coating conductivity paste is the face of separating out, i.e. not only sliding surface, and the roughness on surface uprises.By surface coated conductivity paste, has this advantage of the adhesiveness raising of active material particle and superficial layer 4a at superficial layer 4a with such surface state.
After the dried coating film of paste forms active material layer 3, shown in Fig. 6 (e), on this active material layer, electroplate the low metal material of formation ability of lithium compound, form another current collection superficial layer 4b.As the condition of electroplating, can use the condition identical with the plating in the 1st manufacture method.By suitable this electrolytic condition of regulating, form superficial layer 4b.In addition, the material that constitutes superficial layer 4b is impregnated into the whole zone of thickness direction of active material layer 4, thereby two superficial layer 4a, 4b conduct.And, in superficial layer 4b, easily form previous a large amount of fine pore of narrating.After forming superficial layer 4b, also can connect superficial layer 4a, 4b press process active material layer 3 together, make superficial layer 4a, 4b produce fine pore 5.In addition, also can active material layer 3 be carried out preceding press process prior on active material layer 3, forming superficial layer 4b.
At last, shown in Fig. 6 (f), from superficial layer 4a peel separation foils 1.Obtain negative pole 10 thus.
Because Fig. 6 (a) is a schematic diagram to the process chart shown in Fig. 6 (f), therefore, be expressed as: each superficial layer 4a, 4b separate clearly with active material layer 3, and negative pole 10 is a 3-tier architecture.In fact should be careful: the constituent material of each superficial layer 4a, 4b is impregnated in the active material layer 3, becomes two superficial layer 4a, 4b state connected to one another.
As the method for distinguishing of the 2nd manufacture method, also can use the 3rd manufacture method shown in Fig. 7 (a)-Fig. 7 (e).In the 3rd manufacture method, current collection shown in Fig. 6 (c) in forming the 2nd manufacture method is with before the superficial layer 4a, on foils 11 with the thickness of 0.001-1 μ m form comprise and current collection with the lining body of the material of the different material of the constituent material of superficial layer 4a, the electro-deposition current collection forms this current collection superficial layer 4a with the constituent material of superficial layer by electroplating in the above.
At first shown in Fig. 7 (a), prepare foils 11.Secondly as Fig. 7 (b) shown in, at the device lining of the one side utilization regulation of foils 11 body 22 that is covered.Preferably before lining, foils 11 implemented pre-treatments such as pickling, make its surface cleaning.Lining body 22 is used to, and the electronic conductivity of the formation face by making superficial layer 4a is uneven state, thereby forms a large amount of minute apertures on superficial layer 4a.Lining body 22 preferably be formed its thickness reach 0.001-1 μ m, especially be preferably 0.002-0.5 μ m, especially be preferably 0.005-0.2 μ m.By forming the thickness of this degree, lining body 22 discontinuously, the surface of for example island ground lining foils 11.From more easily form the angle of fine pore 5 on superficial layer 4a, it is favourable forming lining body 22 discontinuously.In Fig. 7 (b), in order to help to understand, the size of the body 22 of emphasizing to be covered and describing.
Lining body 22 comprises the material of the material different with the constituent material of superficial layer 4a.In view of the above in stripping process described later, can be from foils 11 stripper surface layer 4a successfully.The material of the preferably different material of body 22 that particularly is covered with the constituent material of superficial layer 4a, and contain at least a kind of element among Cu, Ni, Co, Mn, Fe, Cr, Sn, Zn, In, Ag, Au, C, Al, Si, Ti and the Pd and constitute.
The formation method of lining body 22 is not particularly limited.For example fastening the formation method of the body 22 of can selecting to be covered with the pass of the formation method of superficial layer 4a.Specifically, adopting the occasion of electroplating formation superficial layer 4a, considering from making aspects such as efficient, preferably, lining body 22 also adopts electroplates formation.Especially also can adopt additive method, for example electroless plating, sputtering method, physical vaporous deposition (PVD), chemical vapour deposition technique (CVD), sol-gal process or ion implantation to form lining body 22.
Adopting the occasion of electroplating formation lining body 22, select suitable electroplating bath or plating condition according to the constituent material of lining body 22.For example in the occasion that constitutes lining body 22 by tin, as plating bath can use have a following composition or the fluoboric acid tin bath.The bath temperature of the occasion of preferred this plating bath of use is about 15-30 ℃, and current density is 0.5-10A/dm 2About.
·SnSO 4??????30-70g/l
·H 2SO 4?????60-150g/l
Cresol sulfonic acid 70-100g/l
As previously discussed like that, lining body 22 is that uneven state uses for the electronic conductivity of the formation face of the superficial layer 4a that makes foils 11.Therefore, if the electronic conductivity of the electronic conductivity of the constituent material of lining body 22 and foils 11 is different greatly, then by forming lining body 22, the electronic conductivity of the formation face of superficial layer 4a becomes uneven state immediately.It for example is the situation of using carbon and so on as the constituent material of lining body 22.On the other hand, use as the constituent material of lining body 22 and to have with the material of the electronic conductivity of foils 11 same degree, for example with the occasion of the various metal materials headed by the tin etc., by forming lining body 22, the electronic conductivity of the formation face of superficial layer 4a does not become uneven state immediately.So in the occasion that is made of lining body 22 such material, the foils 11 that preferably will form lining body 22 is exposed in the oxygen-containing atmosphere under drying regime, in for example atmosphere.Make surface (reaching the face that exposes of the foils 11) oxidation (with reference to Fig. 7 (c)) of lining body 22 thus.By this operation, the electronic conductivity of the formation face of superficial layer 4a becomes uneven state.When carrying out plating described later under this state, the face that exposes of lining body 22 surfaces and foils 11 creates a difference on electrodeposition rate, can easily form fine pore 5 on superficial layer 4a.The degree of oxidation is not critical in the present invention.For example the inventor distinguishes after deliberation, with the foils 11 that has formed lining body 22 in atmosphere, place about 10-30 minute promptly enough.Especially make foils 11 forced oxidations that formed lining body 22 also harmless.
When being exposed to the foils 11 that has formed lining body 22 in the oxygen-containing atmosphere, the reason that is drying regime is in order to carry out oxidation expeditiously.For example in the occasion that adopt to electroplate forms lining body 22, mention foils 11 backs from plating bath and use drying machines etc. to make it dry, be placed on then that official hour gets final product in the atmosphere.As the formation method of lining body 22, use sputtering method and various sedimentations etc. in the occasion of formula method, do not need drying process, form after the lining body 22, remaining untouched to be placed in the atmosphere gets final product.
Make after 22 oxidations of lining body, shown in Fig. 7 (d), form peel ply 11a in the above.Peel ply 11a in stripping process from foils 11 stripper surface layer 4a and forming successfully.Therefore, can not form yet and have fine-pored superficial layer 4a even do not form peel ply 11a.
Secondly, shown in Fig. 7 (e), on the basis that forms peel ply 11a, employing is electroplated and is made the constituent material electro-deposition of superficial layer 4a and form superficial layer 4a.In formed metal forming 4, form a large amount of fine pores.In Fig. 7 (e), the vertex position of depicting as at lining body 22 forms fine pore, but this is for simplicity, and in fact the vertex position at lining body 22 may not form fine pore.Plating bath and plating condition are suitably selected according to the constituent material of superficial layer 4a.For example, can use watt to bathe or the sulfamic acid bath with following composition as plating bath in the occasion that constitutes superficial layer 4a by Ni.The bath temperature of the occasion of preferred these plating bath of use is about 40-70 ℃, and current density is 0.5-20A/dm 2About.
·NiSO 4·6H 2O??150-300g/l
·NiCl 2·6H 2O??30-60g/l
·H 3BO 3????????30-40g/l
Even the formation of the superficial layer 4a in the 3rd manufacture method uses additive method 1 and other methods 2 narrated below also can carry out.In additive method 1, prepare to contain the coating fluid, for example cream of the particle of material with carbon element etc.For example can use acetylene black etc. as material with carbon element.Consider preferred its average grain diameter D of material with carbon element from can easily forming fine-pored aspect 50(by also measuring with laser diffraction and scattering method and sweep type electron microscopic observation) is 2-200nm, is preferably about 10-100nm especially.This coating fluid of coating on the foils 11 of regulation.Coating thickness is preferably 0.001-1 μ m, is preferably especially about 0.05-0.5 μ m.Then, on filming, adopt plating to make the constituent material electro-deposition of superficial layer 4a and form superficial layer 4a.The condition of electroplating can be defined as with the 3rd manufacture method in identical.
In additive method 2, at first preparation contains the plating bath of the constituent material of superficial layer 4a.For example in the occasion that is made of superficial layer 4a Ni, watt bath of preparing before to have narrated or sulfamic acid are bathed and are got final product.In this plating bath, add the particle of material with carbon element and make it suspension.Can use identical with the material with carbon element that in additive method 1, uses as material with carbon element.The particle diameter of material with carbon element also can be decided to be identical with additive method 1.Consider that the amount of the material with carbon element that preferably suspends is 0.5-50g/l, is preferably about 1-10g/l especially from can on superficial layer 4a, easily forming aspect fine-pored in plating bath.Under the state that the stirring plating bath suspends material with carbon element, foils 11 is electroplated, make the constituent material electro-deposition of superficial layer 4a obtain superficial layer 4a.
After adopting above each method to form superficial layer 4a, adopt the operation identical to obtain negative pole 10 with the 2nd manufacture method.
In the 1-of above explanation the 3rd manufacture method, also can be after forming active material layer 3, before electroplating, contain average grain diameter D with the thickness coating of 0.001-1 μ m according to the additive method 1 of previous narration 50Coating fluid for the material with carbon element of 2-200nm makes the constituent material electro-deposition of superficial layer 4b form superficial layer 4b by plating thereon.On superficial layer 4b, also can more easily form a large amount of fine pores in view of the above.
The negative pole of the present embodiment also can adopt the 4th following manufacture method manufacturing.At first, have the vector resin of a large amount of cation exchange bases on the surface, make it to generate the slaine of this cation exchange base with the liquid handling of metal ion.As vector resin with cation exchange base, for example list the surface of handling polyimide resin with the alkaline aqueous solution of NaOH and potassium hydroxide etc., with the imide ring open loop, generate the resin of a large amount of carboxyls.The concentration of alkaline aqueous solution is preferably about 3-10mol/l.The treatment temperature of preferred alkaline aqueous solution is about 20-70 ℃, and the processing time is about 3-10 divides.The polyimide resin of handling with alkaline aqueous solution preferably neutralizes with acid.The open loop that polyimide resin is produced by alkali treatment and the details that forms of metal coated film are recorded in the spy and open in the 2001-73159 communique.
Slaine with reducing agent reduction generation.List sodium borohydride, hypophosphorous acid and salt thereof etc. as reducing agent.Become on vector resin surface by reduction catalyst core above-mentioned metal by overlay film.Then, formed a current collection superficial layer at this by the enterprising electroplating of overlay film.Then, coating contains the conductivity paste of active material particle on superficial layer, forms active material layer.Again active material layer is electroplated, formed another current collection superficial layer.Then, peel off vector resin or with an organic solvent dissolve vector resin, separate this vector resin with superficial layer from a current collection.Obtain the negative pole of the present embodiment in view of the above.About this manufacture method, the not suitable explanation that is suitable for 1-the 3rd manufacture method of relevant previous narration of the point of Te Bieshuominging.
The negative pole 10 of the present embodiment that obtains like this uses with known positive pole, dividing plate, non-aqueous electrolyte and makes nonaqueous electrolytic solution secondary battery.Positive pole is suspension positive active material and conductive agent as required and an adhesive in appropriate solvent, makes anode mixture, be coated on this anode mixture on the collector body and drying after, obtain by rolling system, compacting and then cutting, stamping-out.Use known in the past positive active materials such as lithium nickel composite oxide, complex Li-Mn-oxide, lithium cobalt composite oxide as positive active material.Preferably use synthetic resin system nonwoven fabrics, polyethylene or polypropylene porous film etc. as dividing plate.Nonaqueous electrolytic solution, the occasion of lithium secondary battery is included in the solution that has dissolved in the organic solvent as supporting electrolytical lithium salts.As lithium salts, for example exemplify out LiClO 4, LiAlCl 4, LiPF 6, LiAsF 6, LiSbF 6, LiSCN, LiCl, LiBr, LiI, LiCF 3SO 3, LiC 4F 9SO 3Deng.
Following one side illustrates the 2nd embodiment of negative pole of the present invention on one side with reference to Fig. 8.About the present embodiment, only the explanation point different with the 1st embodiment about the point that does not specify, suits to be suitable for the explanation that is described in detail about the 1st embodiment.In addition, in Fig. 8, attached identical symbol on the member identical with Fig. 1.
As shown in Figure 8, the negative pole of the present embodiment possesses conductive metal paper tinsel layer 8 as core at the central portion of thickness direction.Each face at metal foil layer 8 has formed active material layer 3,3 respectively.And, formed the current collection superficial layer 4a, the 4b that on each active material layer 3,3, are covered respectively.
In each active material layer 3,3, the formation current collection is impregnated into respectively in the whole zone of thickness direction of each active material layer 3,3 with the material of superficial layer 4a, 4b.Active material particle 2 does not expose at electrode surface, but is embedded in each superficial layer 4a, 4b inside.Constitute each superficial layer 4a, 4b.Constitute current collection and permeate the thickness direction of each active material layer 3,3, thereby be connected with metal foil layer 8 with the material of superficial layer 4a, 4b.In view of the above, each superficial layer 4a, 4b and metal foil layer 8 conduct, and more uprise as the electronic conductivity of negative pole integral body.That is to say, the negative pole of the present embodiment also with the negative pole of the 1st embodiment similarly, whole negative pole becomes one and has the current collection function.
The thickness of superficial layer 4a, 4b in the present embodiment and active material layer 3,3 can be defined as identical with the 1st embodiment.About the thickness of metal foil layer 8, consider from thickness that suppresses negative pole integral body and the viewpoint that improves energy density, be preferably 5-40 μ m, be preferably 10-20 μ m especially.From same viewpoint, the thickness of negative pole integral body is preferably 10-100 μ m, is preferably 20-60 μ m especially.
The following summary situation of manufacture method of the negative pole of explanation the present embodiment.At first contain the conductivity paste of active material particle, form active material layer respectively in each face coating of metal foil layer 8.Metal foil layer 8 can be made in advance, perhaps also can be used as an online manufacturing of operation in the manufacturing process of negative pole of the present embodiment.The occasion of metal foil layer 8 online manufacturings preferably separates out manufacturing by electrolysis.After the dried coating film of paste forms active material layer, the metal foil layer 8 that has formed this active material layer is immersed in the electroplating bath of the low metal material of the formation ability that contains lithium compound, under this state, on active material layer, adopt this conductive material to electroplate, form superficial layer 4a, 4b.By making in this way, on superficial layer 4a, 4b, can easily form a large amount of fine pores.In addition, the conductive material that constitutes superficial layer 4a, 4b is impregnated in the whole zone of thickness direction of active material layer, thereby two superficial layers and metal foil layer 8 conduct.
The invention is not restricted to above-mentioned embodiment.For example in the above-described embodiment, constitute current collection and permeate the thickness direction of each active material layer 3, thereby two superficial layers 4 conduct, but under the limit of the current collection that can fully guarantee each superficial layer 4, two superficial layers 4 can not conduct yet with the material of superficial layer 4.
Be described in more detail the present invention by the following examples., scope of the present invention is not limited by these embodiment.In the following example, only otherwise special declaration, " % " is meant " weight % ".
[embodiment 1-1]
(1) manufacturing of active material particle
1400 ℃ the fused solution that will contain silicon 80%, nickel 20% is poured in the mold made of copper, obtains by the ingot casting of the silicon-nickel alloy of chilling.This ingot casting is pulverized, sieved with aeropulverizer, obtain active material particle.Average grain diameter (the D of this particle 50Value) is 5 μ m.
(2) preparation of paste
The paste that has prepared following composition.
The active material particle 16% that in above-mentioned (1), obtains
Acetylene black (particle diameter is 0.1 μ m) 2%
Adhesive (polyvinylidene fluoride) 2%
Retarder thinner (N-methyl pyrrolidone) 80%
(3) formation of peel ply
With the surface that chromate is handled the foils made of copper (thick is that 35 μ m, surface roughness Ra are 0.1 μ m) that obtains by electrolysis, forming thick is the peel ply (with reference to Fig. 4 (a)) of 0.5 μ m.The surface roughness Ra of peel ply also is 0.1 μ m.
(4) formation of active material layer
The above-mentioned paste of coating makes it dry on the peel ply of foils, has formed active material layer (with reference to Fig. 4 (b)).Then, with the pressure roll-in processing (preceding press process) of 0.5t/cm, with the active material layer densificationization.The active material layer thickness that obtains like this is 8 μ m.
(5) the current collection formation of superficial layer
The foils that has formed active material layer is immersed in the electroplating bath with following composition electroplates.
Copper 50g/l
Sulfuric acid 60g/l
Bathe 40 ℃ of temperature
Making current density is 20A/dm 2, electroplate after 70 seconds, mention foils from electroplating bath and obtain negative pole (with reference to Fig. 4 (c)).The current collection of a side that contacts with foils is 1 μ m with the thickness of superficial layer (following superficial layer with these sides is called the 1st superficial layer), and the current collection of a side that does not contact with foils is 1 μ m with the thickness of superficial layer (following superficial layer with these sides is called the 2nd superficial layer).
(6) carrier copper foil peels off
Shown in Fig. 4 (d), on the part of peel ply, peel off negative pole from foils.Obtain the negative pole of structure shown in Figure 1 in view of the above.The a large amount of fine pore that in each superficial layer, exists in the surperficial perforate of this superficial layer and communicate with active material layer.Fine-pored average perforated area and percent opening see Table shown in the 1-1.
[embodiment 1-2]
Except the time of will electroplate was decided to be 60 seconds, other and embodiment 1-1 similarly obtained negative pole.The thickness of the 1st superficial layer is 1 μ m, and the thickness of the 2nd superficial layer is 0.5 μ m.The a large amount of fine pore that in each superficial layer, exists in the surperficial perforate of this superficial layer and communicate with active material layer.Fine-pored average perforated area and percent opening see Table shown in the 1-1.
[embodiment 1-3]
Except the time of will electroplate was decided to be 130 seconds, other and embodiment 1-1 similarly obtained negative pole.The thickness of the 1st superficial layer is 1 μ m, and the thickness of the 2nd superficial layer is 5 μ m.The a large amount of fine pore that in each superficial layer, exists in the surperficial perforate of this superficial layer and communicate with active material layer.Fine-pored average perforated area and percent opening see Table shown in the 1-1.
[embodiment 1-4]
Carry out roll-in processing (preceding press process) after the paste coating with the pressure of 1t/cm, and the time of electroplating is decided to be 50 seconds, in addition, other and embodiment 1-1 similarly obtain negative pole.The thickness of the 1st superficial layer is 0.5 μ m, and the thickness of the 2nd superficial layer is 0.5 μ m.The a large amount of fine pore that in each superficial layer, exists in the surperficial perforate of this superficial layer and communicate with active material layer.Fine-pored average perforated area and percent opening see Table shown in the 1-1.
[embodiment 1-5]
Carry out roll-in processing (preceding press process) after the paste coating with the pressure of 1t/cm, and the time of electroplating is decided to be 120 seconds, in addition, other and embodiment 1-1 similarly obtain negative pole.The thickness of the 1st superficial layer is 0.5 μ m, and the thickness of the 2nd superficial layer is 5 μ m.The a large amount of fine pore that in each superficial layer, exists in the surperficial perforate of this superficial layer and communicate with active material layer.Fine-pored average perforated area and percent opening see Table shown in the 1-1.
[comparative example 1-1]
(1) preparation of paste
The paste that has prepared following composition.
Powdered graphite (particle diameter 10 μ m) 16%
Acetylene black (particle diameter 0.1 μ m) 2%
Adhesive (polyvinylidene fluoride) 2%
Retarder thinner (N-methyl pyrrolidone) 80%
(2) on each face of the Copper Foil of thick 30 μ m, be coated with prepared paste respectively, make it to have formed active material layer in dry.Then the pressure with 0.5t/cm carries out roll-in processing, obtains negative pole.The thickness of each active material layer after the press process is 20 μ m.
[performance evaluation]
The negative pole that use obtains in embodiment and comparative example has been made nonaqueous electrolytic solution secondary battery according to the following stated.Measured irreversible capacity, obtained heap(ed) capacity needed period (below be called the period that obtains heap(ed) capacity), obtaining the capacity density heap(ed) capacity density of per unit weight (below be called) of the per unit weight in the period of heap(ed) capacity, the capacity density heap(ed) capacity density of per unit volume (below be called) that obtains the per unit volume in the period of heap(ed) capacity, the capacity sustainment rate of 50 circulation times with following method.Following table 1-1 expresses these results.
[making of nonaqueous electrolytic solution secondary battery]
As electrode (counter electrode) is used lithium metal, use the above-mentioned negative pole that obtains as the effect utmost point in addition, the two poles of the earth are provided with in opposite directions across dividing plate.And, use LiPF as nonaqueous electrolytic solution 6The mixed solution of/ethylene carbonate and diethyl carbonate (1: 1 Capacity Ratio) adopts usual way to make nonaqueous electrolytic solution secondary battery.
[irreversible capacity]
Irreversible capacity (%)=(the first discharge capacity of 1-/primary charging capacity) * 100
That is, expression has been charged but can not have been discharged, remain in the capacity in the active material.
[obtaining the period of heap(ed) capacity]
After beginning to discharge and recharge, expression obtains the period of maximum discharge capacity.The active bad electrode at initial stage, the period that obtains heap(ed) capacity is big more.
[the heap(ed) capacity density of per unit weight]
Expression obtains discharge capacity in the period of heap(ed) capacity, unit negative pole weight.Unit is mAh/g.Usually, the most discharge capacity of expression units activity substance weight under the situation, but at this for the clear and definite dominance that does not use the thick-film conductor body, the discharge capacity of representation unit negative pole weight.
[the heap(ed) capacity density of per unit volume]
Expression obtains discharge capacity in the period of heap(ed) capacity, unit negative pole volume.Unit is mAh/cm 3Usually, the most discharge capacity of expression units activity material volume or active material layer volume under the situation, but at this for the clear and definite dominance that does not use the thick-film conductor body, the discharge capacity of representation unit negative pole volume.
[the capacity sustainment rates of 50 circulation times]
Discharge capacity/maximum discharge capacity * 100 of capacity sustainment rate (%)=the 50th circulation of 50 circulation times
Table 1-1
Active material Thickness (μ m) Average perforated area (μ m 2) Percent opening (%) Irreversible capacity (%) Obtain the period of heap(ed) capacity The heap(ed) capacity density (mAh/g) of Unit Weight Heap(ed) capacity density (the mAh/cm of unit volume 3) The capacity sustainment rate (%) of 50 circulation times
The 1st superficial layer The 2nd superficial layer Negative pole integral body The 1st superficial layer The 2nd superficial layer The 1st superficial layer The 2nd superficial layer
Embodiment ??1-1 ??Si80+Ni20 ????1 ????1 ??10 ????5 ????4 ????5.6 ??5.8 ????8 ????2 ????330 ????2300 ????98
??1-2 ??Si80+Ni20 ????1 ????0.5 ??10 ????4 ????16 ????5.3 ??15 ????8 ????1 ????370 ????2500 ????98
??1-3 ??Si80+Ni20 ????1 ????5 ??14 ????5 ????0.7 ????4.9 ??0.77 ????8 ????2 ????220 ????1600 ????99
??1-4 ??Si80+Ni20 ????0.5 ????0.5 ??9 ????13 ????15 ????14 ??16 ????7 ????1 ????280 ????2600 ????98
??1-5 ??Si80+Ni20 ????0.5 ????5 ??13 ????14 ????0.7 ????13 ??0.73 ????8 ????1 ????230 ????1700 ????99
Comparative example 1-1 Graphite ????- ????- ??70 ????- ????- ????- ????10 ????1 ????120 ????460 ????100
Distinguish clearly that by the result shown in the table 1-1 irreversible capacity of the negative pole of each embodiment is little.Distinguish that also the period that obtains heap(ed) capacity is little, just high from the initial stage charge/discharge capacity that discharges and recharges.Distinguish that also the capacity density of Unit Weight and monomer volume is high.And distinguish, the capacity sustainment rate height after repeating to discharge and recharge, cycle life is elongated.Though do not express in the table, in the negative pole of each embodiment, the material that constitutes each superficial layer is impregnated into the whole zone of thickness direction of active material layer, thereby two surface layer conductions are logical.In addition, active material particle does not expose in fact in negative terminal surface, but is embedded in the inside of superficial layer.
[embodiment 2-1 and 2-2]
(1) formation of peel ply
The electrolytic copper foil that uses thick 35 μ m is as foils.This foils was at room temperature washed for 30 seconds in pickle.Then, at room temperature washed for 30 seconds with pure water.Then, in 30 seconds of impregnated carrier paper tinsel in remaining 40 ℃ the carboxyl benzotriazole solution of 3g/l, shown in Fig. 6 (b), formed peel ply.And at room temperature washed for 15 seconds with pure water.
The formation of (2) the 1st superficial layers
Impregnated carrier paper tinsel in having the nickel plating bath that following bath forms carries out electrolysis, shown in Fig. 6 (c), has formed and comprises the 1st superficial layer of nickel foil as thin as a wafer.Form on the peel ply of the glassy surface side of the 1st superficial layer in being formed at foils.Current density is decided to be 5A/dm 2, bathe temperature and be decided to be 50 ℃.In anode, used nickel electrode.Power supply uses DC power supply.The thickness of the 1st superficial layer is 3 μ m in embodiment 2-1, is 1 μ m in embodiment 2-2.
Nickel plating bath is formed
NiSO 4·6H 2O??????????????250g/l
NiCl 2·6H 2O??????????????45g/l
H 3BO 3????????????????????30g/l
(3) formation of active material layer
Form and carry out pure water behind the 1st superficial layer and washed for 30 seconds, then dry in atmosphere.Then, coating contains the paste of active material particle on the 1st superficial layer, shown in Fig. 6 (d), has formed the active material layer of thickness 15 μ m.As active material particle, use average grain diameter D 50It is the alloyed powder of the composition of 1.5 μ m with Si 80%-Ni 20%.Paste comprises active material particle, nickel powder, acetylene black and polyvinylidene fluoride (below be called PVdF).It is active material that paste is formed: nickel powder: acetylene black: PVdF=60: 34: 1: 5.
The formation of (4) the 2nd superficial layers
Shown in Fig. 6 (e), on active material layer, form the 2nd superficial layer that constitutes by nickel foil as thin as a wafer by electrolysis.The condition of electrolysis is identical with the formation condition of the 1st superficial layer.But carrying out electrolysis makes thickness reach 3 μ m.
(5) electrode peels off
Shown in Fig. 6 (f), peel off the electrode that obtains like this from foils, as negative pole of the present invention.Fig. 8 is illustrated in the electron micrograph in the cross section of the negative pole that obtains among the embodiment 2-1.
[embodiment 2-3 and 2-4]
Formed ultrathin copper foil by electrolysis as the 1st superficial layer.Bathe composed as follows.Current density is decided to be 20A/dm 2, bathe temperature and be decided to be 40 ℃.In anode, used the size stabilization anode.Power supply uses DC power supply.The thickness of the 1st superficial layer is 3 μ m in embodiment 2-3, is 1 μ m in embodiment 2-4.Then, adopt 10 seconds of BTA solution-treated the 1st superficial layer of the 1g/l that remains on 25 ℃ for the purpose that the 1st superficial layer is carried out antirust processing.Other and embodiment 2-1 similarly obtain negative pole in addition to these.
Copper plating solution is formed
CuSO 4·5H 2O????????????????250g/l
H 2SO 4??????????????????????70g/l
[embodiment 2-5]
Each face coating paste identical with the paste that uses in embodiment 2-1 at the electrolytic copper foil of thick 35 μ m makes thickness reach 15 μ m respectively, makes it drying and formed active material layer.Then, be immersed in to have in the nickel plating bath of forming with the same bath of embodiment 2-1 and carry out electrolysis, formed the superficial layer that constitutes by nickel foil as thin as a wafer as shown in Figure 8 respectively.The condition of electrolysis is identical with embodiment 2-1.The thickness of each superficial layer is decided to be 3 μ m respectively.Obtained negative pole shown in Figure 8 like this.
[comparative example 2-1]
Prepared powdered graphite (average grain diameter D 50=10 μ m): acetylene black (average grain diameter D 50=40nm): PVdF: N-methyl pyrrolidone=16: 2: 2: the paste of 80 mixing ratio (weight ratio).Each face at the Copper Foil of thick 35 μ m is coated with plaster ointment, makes it drying and has formed active material layer.Then, process with the pressure roll-in of 0.5t/cm.The thickness of the single face of the active material layer after the press process is 40 μ m.Obtained negative pole like this.
[comparative example 2-2]
Each face coating paste identical with the paste that uses in embodiment 2-1 at the Copper Foil of thick 35 μ m makes thickness reach 15 μ m respectively, makes it drying and formed active material layer.Obtained negative pole in this wise.
[performance evaluation]
The negative pole that use obtains in embodiment and comparative example has been made nonaqueous electrolytic solution secondary battery with following method.Measure, calculated the capacity sustainment rate of maximum negative discharge capacity, battery capacity and 50 circulation times of this battery with following method.Following table 2-1 expresses these results.In addition, use the negative pole that in embodiment 2-1 and comparative example 2-1 and 2-2, obtains, in to electrode, use lithium metal, make nonaqueous electrolytic solution secondary battery, measured the variation of discharge capacity with respect to the charge and discharge cycles number as the effect utmost point.Figure 12 expresses its result.
[making of nonaqueous electrolytic solution secondary battery]
The negative pole that will obtain in embodiment and comparative example is as the effect utmost point, as electrode is used LiCoO 2, the two poles of the earth are provided with in opposite directions across dividing plate.As nonaqueous electrolytic solution, use LiPF 6The mixed solution of/ethylene carbonate and diethyl carbonate (1: 1 Capacity Ratio) adopts usual way to make nonaqueous electrolytic solution secondary battery.
[maximum negative discharge capacity]
Measured discharge capacity in the circulation that obtains heap(ed) capacity, the units activity substance weight.Unit is mAh/g.
[battery capacity]
Thickness and area by negative pole are obtained volume, calculate the capacity of average unit volume.The electrode that uses comparative example 2-1 is designated as 100 as the capacity of the battery of negative pole, expresses the capacity of other batteries relatively.
[the capacity sustainment rates of 50 circulation times]
Measure the discharge capacity of the 50th circulation, this value is divided by the later maximum negative discharge capacity of the 2nd circulation, multiply by 100 and calculate.
Table 2-1
Active material is formed The 1st superficial layer material/thickness The 2nd superficial layer material/thickness Maximum negative discharge capacity (mAh/g) Battery capacity (vs comparative example 1) The capacity sustainment rate (%) of 50 circulation times
Embodiment 2-1 ????Si 80Ni 20 ???Ni/3μm ???Ni/3μm ????3150 ????150 ????98
Embodiment 2-2 ????Si 80Ni 20 ???Ni/1μm ???Ni/3μm ????3130 ????160 ????96
Embodiment 2-3 ????Si 80Ni 20 ???Cu/3μm ???Ni/3μm ????3120 ????150 ????95
Embodiment 2-4 ????Si 80Ni 20 ???Cu/1μm ???Ni/3μm ????3120 ????160 ????98
Embodiment 2-5 ????Si 80Ni 20 ???- ???Ni/3μm ????3150 ????120 ????98
Comparative example 2-1 ????C ???- ???- ????300 ????100 ????100
Comparative example 2-2 ????Si 80Ni 20 ???- ???- ????3140 ????130 ????15
As show to show shown in the 2-1: used the secondary cell of the electrode that obtains in each embodiment, the capacity sustainment rate of its maximum negative discharge capacity, battery capacity and 50 circulation times is than the secondary cell height that has used the electrode that obtains in each comparative example.In addition, clearly distinguished by result shown in Figure 12: even the negative pole repeated charge of embodiment 2-1, discharge capacity does not reduce yet, and is keeping high level.In contrast to this, the discharge capacity of the negative pole of comparative example 2-1 is extremely low level.Distinguish: though the discharge capacity at the negative pole initial stage of comparative example 2-2 is passed through repeated charge for than higher level, discharge capacity sharply reduces.Though do not show in table, the result of electron microscope observation confirms: in the negative pole of embodiment 2-1 to 2-4, the constituent material of superficial layer is impregnated in the whole zone of thickness direction of active material layer, thereby two surface layer conductions are logical.Confirm again: in the negative pole of embodiment 2-5, the constituent material of superficial layer is impregnated in the whole zone of thickness direction of active material layer, thereby conducts with Copper Foil.And confirm: in the negative pole of embodiment 2-1 to 2-5, in superficial layer, formed the fine pore that a large amount of thickness directions at this superficial layer extends.
[embodiment 3-1]
Acid elution 30 seconds of foils made of copper (thick 35 μ m) of obtaining by electrolysis at room temperature.Then washed for 30 seconds with pure water in room temperature.Then foils is immersed in the zinc-plated bath with following bath composition and electroplates, formed the lining body that constitutes by tin.Current density is decided to be 2A/dm 2, bathe temperature and be decided to be 30 ℃.Anode has used tin electrode.Power supply uses DC power supply.The lining bodily form becomes the thickness of 20nm.After mentioning from plating bath, washed for 30 seconds, in atmosphere, after the drying, place the oxidation of 15 minutes bodies that are covered with pure water.
·SnSO 4??????????50g/l
·H 2SO 4?????????100g/l
Cresol sulfonic acid 100g/l
With the foils that formed lining body dipping 30 seconds in remaining 40 ℃ the carboxyl benzotriazole solution of 3g/l.Carry out peel ply in view of the above and form processing.From solution, mention with pure water after peel ply forms and handles and washed for 15 seconds.
Secondly, foils is immersed in has watt that following bath forms and electroplate in bathing, formed the 1st superficial layer that comprises nickel.Current density is decided to be 5A/dm 2, bathe temperature and be decided to be 50 ℃.Anode has used nickel electrode.Power supply uses DC power supply.Superficial layer forms the thickness of 3 μ m.After mentioning from plating bath, washed for 30 seconds with pure water, dry in atmosphere.Fig. 9 (a) and Fig. 9 (b) express the sweep type electromicroscopic photograph of the superficial layer that obtains like this and the photo under the state of transmitted light.
NiSO 4·6H 2O??????????250g/l
NiCl 2·6H 2O??????????45g/l
H 3BO 3????????????????30g/l
Secondly, on superficial layer, be coated with the paste that contains the negative electrode active material particle and make thickness reach 15 μ m, formed active material layer.Active material particle is the alloy with composition of Si80wt%-Ni20wt%, average grain diameter D 50=1.5 μ m.The composition of paste is an active material: Ni powder: acetylene black: polyvinylidene fluoride=60: 34: 1: 5.
Coating contains average grain diameter D on active material layer 50Be the cream of the material with carbon element (acetylene black) of 40nm, and make thickness reach 0.5 μ m.Then, on this is filmed, under the condition identical, electroplate, formed the 2nd superficial layer that comprises nickel with above-mentioned electrolytic condition.Superficial layer forms the thickness of 3 μ m.
At last, peel off the 1st superficial layer and foils, the active material layer that obtained between a pair of superficial layer clamping and the negative electrode for nonaqueous secondary battery that constitutes.
[performance evaluation]
About the negative pole that obtains in an embodiment, estimate charge characteristic with following method.Figure 10 (a) and Figure 10 (b) express its result.The charge characteristic of the photons (the 1st photons) that Figure 10 (a) expression is peeled off from foils, the charge characteristic of Figure 10 (b) expression lining plating side (the 2nd photons).In addition, measured the fine-pored diameter that forms on the 1st and the 2nd superficial layer of the negative pole that obtains in an embodiment and had density with following method.Following table 3-1 expresses its result.
[evaluation method of charge characteristic]
As electrode is used lithium metal, in addition, use the electrode that obtains in an embodiment as the effect utmost point, the two poles of the earth are provided with in opposite directions across dividing plate.Use LiPF as nonaqueous electrolytic solution 6The mixed solution of/ethylene carbonate and diethyl carbonate (1: 1 Capacity Ratio) adopts usual way to make nonaqueous electrolytic solution secondary battery.Use this battery at charge condition 0.2mA/cm 2, estimate under the voltage range 0-2.8V.
[fine-pored diameter and have the assay method of density]
Peel off this superficial layer from the foils that has only formed the 1st superficial layer, the dorsal part in the darkroom from superficial layer sees through light, takes the photo of superficial layer under the sort of state.Resolving this photo by image obtains fine-pored diameter and has density.
Table 3-1
The 1st metal forming (foils is peeled off side) The 2nd metal forming (lining plating side)
Minute aperture exist density (individual/cm 2) Thickness (μ m) Minute aperture exist density (individual/cm 2) Thickness (μ m)
The diameter of minute aperture is 0.01 μ m to 10 μ m The diameter of minute aperture is greater than 10 μ m but be no more than 200 μ m The diameter of minute aperture is 0.01 μ m to 10 μ m The diameter of minute aperture is greater than 10 μ m and be no more than 200 μ m
Embodiment 3-1 ????670 ??????0 ???3 ????550 ??????0 ????3
Clearly show by table 3-1 and result shown in Figure 10, the negative pole of embodiment, foils peels off side and lining plating side all obtains sufficient capacity.The negative pole that this means embodiment is supplied to active material layer fully by the 1st and the 2nd superficial layer electrolyte.
[embodiment 4-1]
(1) manufacturing of active material particle
1400 ℃ the fused solution that will contain silicon 80%, nickel 20% is poured in the mold made of copper, obtains by the ingot casting of the silicon-nickel alloy of chilling.This ingot casting is pulverized, sieved with aeropulverizer, obtain active material particle.The active material particle that obtains put among 20% the KOH, corroded 20 minutes.
Table 4-1 expresses the average grain diameter of active material particle, total oxygen concentration and the most surperficial O/Si ratio.
(2) preparation of paste
The paste that has prepared following composition.
The active material particle 16% that in above-mentioned (1), obtains
Acetylene black (particle diameter 0.1 μ m) 2%
Bonding agent (polyvinylidene fluoride) 2%
Retarder thinner (N-methyl pyrrolidone) 80%
The formation of superficial layer of (3) the 1st current collections
Shown in Fig. 6 (b), on the carrier copper foil of thick 35 μ m, form the peel ply that comprises carboxyl benzotriazole.Then shown in Fig. 6 (c), on peel ply, implement plating Ni, formed the 1st current collection superficial layer of thick 3 μ m.
(4) formation of active material layer
Shown in Fig. 6 (d), be coated with plaster ointment on superficial layer and make it dry at the 1st current collection.Dried thick coating is 10 μ m.
The formation of superficial layer of (5) the 2nd current collections
Shown in Fig. 6 (e), on active material layer, implement plating Ni, formed the 2nd current collection superficial layer of thick 3 μ m.
(6) carrier copper foil peels off
Shown in Fig. 6 (f), peel off carrier copper foil from the 1st current collection with superficial layer in the part of peel ply.Obtain the negative pole of structure shown in Figure 1 in view of the above.
[embodiment 4-2]
Replace KOH to use HF as corrosive liquid, similarly obtain active material particle with embodiment 4-1 in addition.The concentration of HF is 5%, and etching time is 10 minutes.With embodiment 4-1 similarly obtain negative pole thereafter.
[embodiment 4-3]
Replace KOH to use NH as corrosive liquid 4F obtains active material particle in addition similarly to Example 1.NH 4The concentration of F is 5%, and etching time is 10 minutes.With embodiment 4-1 similarly obtain negative pole thereafter.
[embodiment 4-4]
Replace KOH to use hydrazine as corrosive liquid, similarly obtain active material particle with embodiment 4-1 in addition.The concentration of hydrazine is 1%, and etching time is 60 minutes.With embodiment 4-1 similarly obtain negative pole thereafter.
[embodiment 4-5 and 4-6]
Handle the active material particle that in embodiment 4-1, obtains with the Ni electroless plating, formed the Ni film.The Ni film thickness sees Table shown in the 4-2.Similarly obtain negative pole with embodiment 4-1 then.The bath of electroless plating is composed as follows.
·NiSO 4·6H 2O??????25g/l
·NaH 2PO 2·H 2O????20g/l
·Na 3C 6H 5O 7??????25g/l
·NaC 3H 5O 2????????10g/l
[embodiment 4-7 and 4-8]
Handle the active material particle that in embodiment 4-2, obtains with the Ni electroless plating, formed the Ni film.The Ni film thickness sees Table shown in the 4-2.Similarly obtain negative pole with embodiment 4-1 then.The bath composition of electroless plating is identical with embodiment 4-5.
[embodiment 4-9]
The method that the active material particle that use obtains in embodiment 4-8 adopts and embodiment 4-1 is same has prepared paste.The prepared paste of coating and make it dry on each face of the Copper Foil of thick 18 μ m.The thickness of dried active material layer is respectively 10 μ m.The Copper Foil that has formed active material layer is immersed in the plating Ni bath electroplated Ni on each active material layer.Obtain the negative pole of structure shown in Figure 8 in view of the above.
[performance evaluation]
The negative pole that use obtains in each embodiment is according to following such nonaqueous electrolytic solution secondary battery of having made.Maximum discharge capacity and 50 circulation volume sustainment rates have been measured about this battery with above-mentioned method.Following table 4-1 and table 4-2 express these results.In addition, about embodiment 4-5 and 4-9, obtain the plating current efficiency of the 2nd current collection in superficial layer formation when making negative pole.The oxygen concentration of active material particle is low more, and plating current efficiency approaches 100% more.
[making of nonaqueous electrolytic solution secondary battery]
As electrode is used lithium metal, in addition, use the negative pole that in above-mentioned, obtains as the effect utmost point, the two poles of the earth are provided with in opposite directions across dividing plate.And, use LiPF as nonaqueous electrolytic solution 6The mixed solution of/ethylene carbonate and diethyl carbonate (1: 1 Capacity Ratio) adopts usual way to make nonaqueous electrolytic solution secondary battery.
Table 4-1
Average grain diameter D 50???μm Form Oxygen concentration The electrode charge and discharge characteristic
Total oxygen demand/wt% ※1 The most surperficial O/Si ratio ※2 Maximum discharge capacity mAh/g 50 circulation volume sustainment rate %
Embodiment 4-1 ????2.5 ??Si80+Ni20 ?????0.7 ?????0.4 ????2500 ????95
Embodiment 4-2 ????2.0 ??Si80+Ni20 ?????0.5 ?????0.3 ????2500 ????97
Embodiment 4-3 ????2.0 ??Si80+Ni20 ?????0.5 ?????0.3 ????2500 ????97
Embodiment 4-4 ????2.5 ??Si80+Ni20 ?????0.7 ?????0.4 ????2500 ????95
※ 1 carrier of oxygen analysis
※ 2 Auger electron spectroscopies
※ 3 does not corrode
Table 4-2
Average grain diameter D 50?μm ※3 Form Oxygen concentration Coating metal thickness μ m Plating current efficiency % The electrode charge and discharge characteristic
Total oxygen demand wt% ※1 Metallic film border O/Si ratio ※2 Maximum discharge capacity mAh/g 50 circulation volume sustainment rate %
Embodiment 4-5 ???2.5 ??Si80+Ni20 ???0.7 ?????0.4 ?????0.05 ????85 ????2500 ????96
Embodiment 4-6 ???2.5 ??Si80+Ni20 ???0.7 ?????0.4 ?????0.5 ????88 ????2500 ????97
Embodiment 4-7 ???2.0 ??Si80+Ni20 ???0.5 ?????0.3 ?????0.05 ????87 ????2500 ????98
Embodiment 4-8 ???2.0 ??Si80+Ni20 ???0.5 ?????0.3 ?????0.5 ????90 ????2500 ????98
Embodiment 4-9 ※4 ???2.0 ??Si80+Ni20 ???0.5 ?????0.3 ?????0.5 ????90 ????2500 ????98
※ 1 carrier of oxygen analysis
※ 2 Auger electron spectroscopies
Value before the lining of ※ 3 usefulness metal coated films
※ 4 has made the negative pole of structure shown in Figure 8.
Distinguish clearly that by the result shown in table 4-1 and the table 4-2 maximum discharge capacity of each embodiment is all high, in addition, the capacity sustainment rate is also high.
Negative electrode for nonaqueous secondary battery of the present invention owing to active material does not expose at electrode surface, but is embedded in electrode interior, has therefore prevented that active material from coming off, in addition, even repeated charge is also guaranteed the current collection of active material.In addition, prevented from effectively to have the isolated active material of electricity, can obtain sufficient current collection.Used the secondary cell of this negative pole just high from the initial stage charge/discharge capacity that discharges and recharges.In addition, even the repeated charge degradation ratio is also low, cycle life is elongated significantly, and efficiency for charge-discharge also uprises.On this basis, owing to do not use the conductive metal paper tinsel layer as core, the collector body that promptly uses in negative pole in the past, therefore, the ratio that can make active material account for negative pole integral body is higher than negative pole in the past.Its result can access the high secondary battery cathode of energy density of average unit volume and average Unit Weight.

Claims (26)

1. negative electrode for nonaqueous secondary battery, it is characterized in that possessing: a pair of current collection that contacts with electrolyte of surface is with superficial layer with between this is to superficial layer and contain the active material layer of one deck at least of the high active material particle of the formation ability of lithium compound.
2. negative electrode for nonaqueous secondary battery according to claim 1 wherein, constitutes the whole zone of thickness direction that described material is impregnated into described active material layer, makes the two sides conduct, and entire electrode becomes one and has the current collection function.
3. negative electrode for nonaqueous secondary battery according to claim 1, wherein, the thickness of described superficial layer is 0.3-10 μ m.
4. negative electrode for nonaqueous secondary battery according to claim 1, wherein, described superficial layer comprises the low metal material of formation ability of lithium compound.
5. negative electrode for nonaqueous secondary battery according to claim 1, wherein, described superficial layer comprises the alloy of copper, nickel, iron, cobalt or these metals.
6. negative electrode for nonaqueous secondary battery according to claim 1, wherein, described superficial layer forms by plating.
7. negative electrode for nonaqueous secondary battery according to claim 1 wherein, is formed with a large amount of fine pores that can extend and soak into nonaqueous electrolytic solution to the thickness direction of this superficial layer at described superficial layer.
8. negative electrode for nonaqueous secondary battery according to claim 7 is characterized in that, described fine pore communicates with described active material layer, and the described fine-pored average perforated area at least one side's the described superficial layer is 0.1-50 μ m 2, and percent opening is 0.1-20%, do not have the thick-film conductor body that current collection is used.
9. negative electrode for nonaqueous secondary battery according to claim 1, wherein, described active material particle comprises the particle of silicon based material or tin based material.
10. negative electrode for nonaqueous secondary battery according to claim 9, wherein, described active material particle is the particle of silicon or tin simple substance.
11. negative electrode for nonaqueous secondary battery according to claim 9, wherein, described active material particle is the stuff and other stuff of silicon or tin and carbon at least, and this stuff and other stuff contains the silicon of 10-90 weight % or the carbon of tin and 90-10 weight %.
12. negative electrode for nonaqueous secondary battery according to claim 9, wherein, described active material particle is the stuff and other stuff of silicon or tin and metal, what this stuff and other stuff contained the silicon of 30-99.9 weight % or tin and 0.1-70 weight % is selected from Cu, Ag, Li, Ni, Co, Fe, Cr, Zn, B, Al, Ge, Sn (wherein, described particle contains except the situation of tin), one or more elements of Si (wherein, described particle contains except the situation of silicon), In, V, Ti, Y, Zr, Nb, Ta, W, La, Ce, Pr, Pd and Nd.
13. negative electrode for nonaqueous secondary battery according to claim 9, wherein, described active material particle is the particle of silicon compound or tin compound, the particle of this silicon compound or tin compound contains the Cu that is selected from of the silicon of 30-99.9 weight % or tin and 0.1-70 weight %, Ag, Li, Ni, Co, Fe, Cr, Zn, B, Al, Ge, Sn (wherein, described particle contains except the situation of tin), Si (wherein, described particle contains except the situation of silicon), In, V, Ti, Y, Zr, Nb, Ta, W, La, Ce, Pr, one or more elements of Pd and Nd.
14. negative electrode for nonaqueous secondary battery according to claim 9, wherein, described active material particle is the stuff and other stuff of the particle and the metallic of silicon compound or tin compound, described stuff and other stuff contains the Cu that is selected from of the particle of the silicon compound of 30-99.9 weight % or tin compound and 0.1-70 weight %, Ag, Li, Ni, Co, Fe, Cr, Zn, B, Al, Ge, Sn (wherein, described compound particles contains except the situation of tin), Si (wherein, described compound particles contains except the situation of silicon), In, V, Ti, Y, Zr, Nb, Ta, W, La, Ce, Pr, one or more elements of Pd and Nd, described compound particles contains the Cu that is selected from of the silicon of 30-99.9 weight % or tin and 0.1-70 weight %, Ag, Li, Ni, Co, Fe, Cr, Zn, B, Al, Ge, Sn (wherein, described compound particles contains except the situation of tin), Si (wherein, described compound particles contains except the situation of silicon), In, V, Ti, Y, Zr, Nb, Ta, W, La, Ce, Pr, one or more elements of Pd and Nd.
15. negative electrode for nonaqueous secondary battery according to claim 9, wherein, described active material particle is the particle that the particle surface coated metal at elementary silicon or tin simple substance forms, this metal is to be selected from Cu, Ag, Ni, Co, Fe, Cr, Zn, B, Al, Ge, Sn (wherein, described particle contains except the situation of tin), Si (wherein, described particle contains except the situation of silicon), In, V, Ti, Y, Zr, Nb, Ta, W, La, Ce, Pr, one or more elements of Pd and Nd, described particle contain the silicon of 30-99.9 weight % or the described metal of tin and 0.1-70 weight %.
16. negative electrode for nonaqueous secondary battery according to claim 1, wherein, described active material particle contains silicon, average grain diameter (D 50) be 0.1-10 μ m, the oxygen concentration less than 2.5 weight % of described active material particle, and surpass 1/2 of oxygen concentration at the most surperficial silicon concentration.
17. negative electrode for nonaqueous secondary battery according to claim 1, wherein, the maximum particle diameter of described active material particle is 50 μ m or following.
18. negative electrode for nonaqueous secondary battery according to claim 1, wherein, the conductivity paste that described active material layer coating contains described active material particle forms.
19. negative electrode for nonaqueous secondary battery according to claim 1 wherein, does not possess conductive metal paper tinsel layer as core at the central portion of thickness direction, whole thickness is 2-50 μ m.
20. negative electrode for nonaqueous secondary battery according to claim 1, wherein, possesses conductive metal paper tinsel layer at the central portion of thickness direction as core, each face at this metal foil layer forms described active material layer respectively, form the described current collection superficial layer of each active material layer of lining more respectively, whole thickness is 10-100 μ m.
21. the manufacture method of the described negative electrode for nonaqueous secondary battery of claim 1 is characterized in that, coating contains the conductivity paste of active material particle on foils, forms active material layer; The described foils that has formed this active material layer is immersed in the electroplating bath that contains metal material electroplates, form the electrode that contains described active material layer; Then from the described electrode of described foils peel separation.
22. the manufacture method of negative electrode for nonaqueous secondary battery according to claim 21, wherein, before forming described active material layer on the described foils, on this foils, electroplate the low metal material of formation ability of lithium compound, form a side current collection superficial layer; With forming described active material layer on the superficial layer, on this active material layer, electroplate the low metal material of formation ability of lithium compound at this current collection, form the opposing party's current collection superficial layer; Then, from a described side's current collection with the described foils of superficial layer peel separation.
23. the manufacture method of negative electrode for nonaqueous secondary battery according to claim 22, wherein, before the current collection that forms a described side is with superficial layer, on described foils, form by the lining body that constitutes with the material of the different material of the constituent material of superficial layer with described current collection with the thickness of 0.001-1 μ m, make of the constituent material electro-deposition of described current collection by plating in the above, form described current collection superficial layer with superficial layer.
24. the manufacture method of the described negative electrode for nonaqueous secondary battery of claim 1, it is characterized in that, the vector resin that has a large amount of cation exchange bases with the liquid handling of metal ion on the surface, make it to generate the slaine of this cation exchange base, reduce this slaine, become on the described surface of vector resin catalyst core described metal by overlay film, this by overlay film power on the plating lithium compound the low metal material of formation ability, form a side current collection superficial layer, this current collection with superficial layer on coating contain the conductivity paste of active material particle, form active material layer, on this active material layer, electroplate the low metal material of formation ability of lithium compound, form the opposing party's current collection superficial layer, separate described vector resin by peeling off or dissolving with superficial layer then from a described side's current collection.
25. the manufacture method of the described negative electrode for nonaqueous secondary battery of claim 20, it is characterized in that, the conductivity paste that contains active material particle in each face coating of conductive metal paper tinsel, form active material layer respectively, this conductive metal paper tinsel that has formed this active material layer is immersed in the electroplating bath of the low metal material of the formation ability that contains lithium compound and electroplates.
26. a nonaqueous electrolytic solution secondary battery, it possesses the described negative electrode for nonaqueous secondary battery of claim 1.
CNB2003801029990A 2003-04-23 2003-12-17 Negative electrode for nonaqueous electrolyte secondary battery, method for manufacturing same and nonaqueous electrolyte secondary battery Expired - Fee Related CN100340015C (en)

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CN101485013B (en) * 2006-06-30 2011-11-02 三井金属矿业株式会社 Negative electrode for non-aqueous electrolyte secondary battery

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DE69531849T2 (en) * 1994-05-30 2004-08-05 Canon K.K. Rechargeable lithium battery
JPH08124579A (en) * 1994-08-30 1996-05-17 Sumitomo Electric Ind Ltd Manufacture of metallic porous material and electrode for storage battery
JP3717085B2 (en) * 1994-10-21 2005-11-16 キヤノン株式会社 Negative electrode for secondary battery, secondary battery having the negative electrode, and method for producing electrode
JPH11135120A (en) * 1997-10-27 1999-05-21 Kao Corp Negative electrode material for nonaqueous secondary battery
JP2001073159A (en) * 1999-09-01 2001-03-21 Nippon Riironaaru Kk Formation of electric conductive film on surface of polyimide resin
JP4152086B2 (en) * 2001-03-23 2008-09-17 三洋電機株式会社 Electrode for lithium secondary battery and lithium secondary battery

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CN101330138B (en) * 2007-06-20 2010-12-01 日产自动车株式会社 Battery electrode
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