WO2011065503A1 - 電気デバイス用Si合金負極活物質 - Google Patents
電気デバイス用Si合金負極活物質 Download PDFInfo
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- WO2011065503A1 WO2011065503A1 PCT/JP2010/071168 JP2010071168W WO2011065503A1 WO 2011065503 A1 WO2011065503 A1 WO 2011065503A1 JP 2010071168 W JP2010071168 W JP 2010071168W WO 2011065503 A1 WO2011065503 A1 WO 2011065503A1
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- active material
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C14/00—Alloys based on titanium
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C18/00—Alloys based on zinc
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C30/00—Alloys containing less than 50% by weight of each constituent
- C22C30/06—Alloys containing less than 50% by weight of each constituent containing zinc
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
- H01M4/386—Silicon or alloys based on silicon
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
- H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
- H01M4/134—Electrodes based on metals, Si or alloys
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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
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Definitions
- the present invention relates to a Si alloy negative electrode active material for electric devices and an electric device using the Si alloy negative electrode active material for electric devices.
- the Si alloy negative electrode active material for an electric device of the present invention and an electric device using the same include, for example, a driving power source for a motor of a vehicle such as an electric vehicle, a fuel cell vehicle, and a hybrid electric vehicle as a secondary battery or a capacitor, Used for auxiliary power.
- lithium ion secondary batteries As a secondary battery for driving a motor, it is required to have extremely high output characteristics and high energy as compared with a consumer lithium ion secondary battery used for a mobile phone, a notebook personal computer or the like. Therefore, lithium ion secondary batteries having the highest theoretical energy among all the batteries are attracting attention, and are currently being developed rapidly.
- a lithium ion secondary battery includes a positive electrode in which a positive electrode active material or the like is applied to both surfaces of a positive electrode current collector using a binder, and a negative electrode in which a negative electrode active material or the like is applied to both surfaces of a negative electrode current collector using a binder.
- a positive electrode in which a positive electrode active material or the like is applied to both surfaces of a positive electrode current collector using a binder
- a negative electrode in which a negative electrode active material or the like is applied to both surfaces of a negative electrode current collector using a binder.
- it has the structure connected through an electrolyte layer and accommodated in a battery case.
- a battery using a material that is alloyed with Li for the negative electrode is expected as a negative electrode material for vehicle use because the energy density is improved as compared with a conventional carbon / graphite negative electrode material.
- a lithium ion secondary battery using a material that is alloyed with Li for the negative electrode has a large expansion and contraction in the negative electrode during charge and discharge.
- the volume expansion is about 1.2 times in graphite materials
- Si materials when Si and Li are alloyed, transition from the amorphous state to the crystalline state causes a large volume change. (About 4 times), there is a problem of reducing the cycle life of the electrode.
- the capacity and the cycle durability are in a trade-off relationship, and there is a problem that it is difficult to improve the high cycle durability while exhibiting a high capacity.
- a negative electrode active material for a lithium ion secondary battery including an amorphous alloy having the formula: Si x M y Al z has been proposed (see, for example, Patent Document 1).
- M represents Mn, Mo, Nb, W, Ta, Fe, Cu, It is a metal composed of at least one of Ti, V, Cr, Ni, Co, Zr and Y.
- paragraph “0018” describes that, by minimizing the content of metal M, a good cycle life is exhibited in addition to high capacity.
- an object of the present invention is to provide a negative electrode active material (also simply referred to as a negative electrode active material) for an electric device such as a Li ion secondary battery that maintains a high cycle characteristic and has a high initial capacity and a well-balanced characteristic. There is to do.
- the object of the present invention can be achieved by a negative electrode active material for an electric device containing an alloy having the composition formula Si x Ti y Zn z .
- the alloy having the above composition formula contains the first additive element Ti within the above range, whereby an amorphous-crystalline phase is obtained. The effect of suppressing the transition and improving the cycle life is obtained. Further, when Si and Li are alloyed, the alloy having the above composition formula contains the second additive element Zn within the above range, so that the capacity as the electrode decreases even when the concentration of the first additive element increases. The effect of not doing is obtained. As a result of such a composite action, the negative electrode active material including the alloy having the above composition formula has a useful effect of having a high initial capacity and high capacity and high cycle durability.
- FIG. 1 is a schematic cross-sectional view schematically showing an outline of a laminated flat non-bipolar lithium ion secondary battery which is a typical embodiment of an electric device according to the present invention.
- FIG. 1 is a perspective view schematically showing the appearance of a stacked flat lithium ion secondary battery that is a representative embodiment of an electric device according to the present invention.
- Si-Ti in which the discharge capacity (mAhg) of the first cycle of the battery using each sample (sample numbers 1 to 25) performed in Example 1 was plotted according to the size of the capacity (color added).
- FIG. 3 is a composition diagram of a —Zn-based ternary alloy.
- FIG. 4 is a composition diagram of a plotted Si—Ti—Zn ternary alloy.
- FIG. 4 is a drawing in which the composition range of the Si—Ti—Zn ternary alloy of FIG. 3 is surrounded by color-coded (with light and shade) the composition range of the Si—Ti—Zn alloy sample of Example 1.
- FIG. 4 is a composition diagram of a plotted Si—Ti—Zn ternary alloy.
- FIG. 4 is a drawing in which the composition range of the Si—Ti—Zn ternary alloy of FIG. 3 is surrounded by color-coded (with light and shade) the composition range of the Si—Ti—Zn alloy sample of Example 1.
- FIG. 4 is a drawing in which a preferred composition range of the Si—Ti—Zn alloy sample of Example 1 is color-coded (shaded) with the composition diagram of the Si—Ti—Zn ternary alloy of FIG. .
- a more preferable composition range of the Si—Ti—Zn alloy sample of Example 1 is color-coded (shaded) and enclosed. is there.
- Si + Ti + Zn (all units are wt% / 100) 1.00, (2) 0.38 ⁇ Si (wt% / 100) ⁇ 0.72, and (3) 0.08.
- a particularly preferred composition range of the Si—Ti—Zn alloy sample of Example 1 is color-coded (with shading) and enclosed. is there.
- Si + Ti + Zn (all units are wt% / 100) 1.00, (2) 0.38 ⁇ Si (wt% / 100) ⁇ 0.61, and (3) 0.19.
- a negative electrode active material for a lithium ion secondary battery which is a typical embodiment of a negative electrode active material for an electric device according to the present invention
- a negative electrode and a lithium ion secondary battery using the same a cell (single The voltage of the battery layer) is large, and high energy density and high power density can be achieved. Therefore, the negative electrode and the lithium ion secondary battery using the negative electrode active material for the lithium ion secondary battery of the present embodiment are excellent for use as a vehicle driving power source or an auxiliary power source. As a result, it can be suitably used as a lithium ion secondary battery for a vehicle driving power source or the like.
- the present invention can be sufficiently applied to lithium ion secondary batteries for portable devices such as mobile phones.
- the lithium ion secondary battery that is the subject of the present embodiment may be any one that uses the negative electrode active material for the lithium ion secondary battery of the present embodiment described below. It should not be restricted in particular.
- the lithium ion secondary battery when distinguished by form / structure, it can be applied to any conventionally known form / structure such as a stacked (flat) battery or a wound (cylindrical) battery. Is.
- a stacked (flat) battery structure By adopting a stacked (flat) battery structure, long-term reliability can be secured by a sealing technique such as simple thermocompression bonding, which is advantageous in terms of cost and workability.
- a solution electrolyte type battery using a solution electrolyte such as a nonaqueous electrolyte solution for the electrolyte layer, a polymer battery using a polymer electrolyte for the electrolyte layer, etc. It can be applied to any conventionally known electrolyte layer type.
- the polymer battery is further divided into a gel electrolyte type battery using a polymer gel electrolyte (also simply referred to as a gel electrolyte) and a solid polymer (all solid) type battery using a polymer solid electrolyte (also simply referred to as a polymer electrolyte). It is done.
- the non-bipolar (internal parallel connection type) lithium ion secondary battery using the negative electrode active material for the lithium ion secondary battery of this embodiment will be described very simply with reference to the drawings.
- the technical scope of the lithium ion secondary battery of the present embodiment should not be limited to these.
- FIG. 1 schematically shows the overall structure of a flat (stacked) lithium ion secondary battery (hereinafter also simply referred to as “stacked battery”), which is a typical embodiment of the electrical device of the present invention.
- stacked battery a flat (stacked) lithium ion secondary battery
- the stacked battery 10 of the present embodiment has a structure in which a substantially rectangular power generation element 21 in which a charge / discharge reaction actually proceeds is sealed inside a laminate sheet 29 that is an exterior body.
- the positive electrode in which the positive electrode active material layer 13 is disposed on both surfaces of the positive electrode current collector 11, the electrolyte layer 17, and the negative electrode active material layer 15 is disposed on both surfaces of the negative electrode current collector 12. It has a configuration in which a negative electrode is laminated. Specifically, the negative electrode, the electrolyte layer, and the positive electrode are laminated in this order so that one positive electrode active material layer 13 and the negative electrode active material layer 15 adjacent thereto face each other with the electrolyte layer 17 therebetween. .
- the adjacent positive electrode, electrolyte layer, and negative electrode constitute one unit cell layer 19. Therefore, it can be said that the stacked battery 10 shown in FIG. 1 has a configuration in which a plurality of single battery layers 19 are stacked and electrically connected in parallel.
- the positive electrode current collector 13 on the outermost layer located on both outermost layers of the power generating element 21 is provided with the positive electrode active material layer 13 only on one side, but the active material layer may be provided on both sides. . That is, instead of using a current collector dedicated to the outermost layer provided with an active material layer only on one side, a current collector having an active material layer on both sides may be used as it is as an outermost current collector. Further, by reversing the arrangement of the positive electrode and the negative electrode as compared with FIG. 1, the outermost negative electrode current collector is positioned on both outermost layers of the power generation element 21, and one side of the outermost negative electrode current collector or A negative electrode active material layer may be disposed on both sides.
- the positive electrode current collector 11 and the negative electrode current collector 12 are attached to a positive electrode current collector plate 25 and a negative electrode current collector plate 27 that are electrically connected to the respective electrodes (positive electrode and negative electrode), and are sandwiched between end portions of the laminate sheet 29. Thus, it has a structure led out of the laminate sheet 29.
- the positive electrode current collector plate 25 and the negative electrode current collector plate 27 are ultrasonically welded to the positive electrode current collector 11 and the negative electrode current collector 12 of each electrode via a positive electrode lead and a negative electrode lead (not shown), respectively, as necessary. Or resistance welding or the like.
- the lithium ion secondary battery described above is characterized by the composition of the negative electrode active material.
- main components of the battery including the negative electrode active material will be described.
- the active material layer 13 or 15 contains an active material, and further contains other additives as necessary.
- the positive electrode active material layer 13 includes a positive electrode active material.
- Examples of the positive electrode active material include lithium-transition metal composite oxides, lithium-transition metal phosphate compounds, lithium-transition metal sulfate compounds, solid solution systems, ternary systems, NiMn systems, NiCo systems, and spinel Mn systems. It is done.
- Examples of the lithium-transition metal composite oxide include LiMn 2 O 4 , LiCoO 2 , LiNiO 2 , Li (Ni, Mn, Co) O 2 , Li (Li, Ni, Mn, Co) O 2 , LiFePO 4 and Examples include those in which some of these transition metals are substituted with other elements.
- Examples of the ternary system include nickel / cobalt / manganese (composite) positive electrode materials.
- Examples of the spinel Mn system include LiMn 2 O 4 .
- Examples of the NiMn system include LiNi 0.5 Mn 1.5 O 4 .
- Examples of the NiCo system include Li (NiCo) O 2 . In some cases, two or more positive electrode active materials may be used in combination.
- a lithium-transition metal composite oxide is used as the positive electrode active material.
- positive electrode active materials other than those described above may be used.
- the optimum particle size for expressing the unique effect of each active material is different, the optimum particle size for expressing each unique effect may be blended and used. It is not always necessary to make the particle size uniform.
- the average particle diameter of the positive electrode active material contained in the positive electrode active material layer 13 is not particularly limited, but is preferably 1 to 20 ⁇ m from the viewpoint of high output. In the present specification, between any two points on the contour line of the active material particles (observation surface) observed using an observation means such as a scanning electron microscope (SEM) or a transmission electron microscope (TEM). It means the maximum distance among the distances.
- the value of “average particle size” is the average value of the particle size of particles observed in several to several tens of fields using an observation means such as a scanning electron microscope (SEM) or a transmission electron microscope (TEM). The calculated value shall be adopted.
- the particle diameters and average particle diameters of other components can be defined in the same manner.
- the positive electrode (positive electrode active material layer) can be applied by any one of a kneading method, a sputtering method, a vapor deposition method, a CVD method, a PVD method, an ion plating method, and a thermal spraying method in addition to a method of applying (coating) a normal slurry. Can also be formed.
- the negative electrode active material layer 15 has a negative electrode active material containing an alloy having the composition formula Si x Ti y Zn z of the present embodiment.
- the negative electrode active material of this embodiment it becomes a favorable negative electrode for lithium ion secondary batteries which has high capacity
- a lithium ion secondary battery having high battery capacity and excellent battery characteristics with excellent cycle durability can be obtained.
- the first additive element Ti that suppresses the amorphous-crystal phase transition and improves the cycle life, and the capacity as the electrode does not decrease even when the concentration of the first additive element increases.
- the second additive element species Zn is selected, and these additive element species and the high-capacity element Si are made to have an appropriate composition ratio.
- the amorphous-crystal phase transition is suppressed because, in the Si material, when Si and Li are alloyed, the amorphous state transitions to the crystalline state, causing a large volume change (about 4 times). For this reason, the particles themselves are broken and the function as the active material is lost. Therefore, by suppressing the amorphous-crystal phase transition, it is possible to suppress the collapse of the particles themselves, maintain the function as the active material (high capacity), and improve the cycle life.
- the first and second additive elements and setting the additive element species and the high capacity element Si to an appropriate composition ratio, it is possible to provide a Si alloy negative electrode active material having a high capacity and high cycle durability.
- the composition ratio of the Si—Ti—Zn alloy is within the range surrounded by the thick solid line in FIG. 5 (inside the triangle), the composition ratio is extremely high that cannot be realized with an existing carbon-based negative electrode active material. High capacity can be realized. Similarly, a higher capacity (initial capacity of 690 mAh / g or more) can be realized than the existing Sn-based alloy negative electrode active material.
- x + y + z 100, (2) 38 ⁇ x ⁇ 100, and (3) 0 ⁇ y ⁇ 42. (4) 0 ⁇ z ⁇ 39.
- the composition ratio of Ti as the first additive element and Zn as the second additive element and the high-capacity element Si is within the appropriate range specified above, a Si alloy negative electrode active material having good characteristics is obtained.
- the Si alloy negative electrode having better characteristics An active material can be provided. Specifically, even when the composition ratio of the Si—Ti—Zn alloy is within the range surrounded by the thick solid line in FIG. 7 (inside the hexagon), it is remarkably impossible with the existing carbon-based negative electrode active material.
- the Si alloy negative electrode having particularly good characteristics when the composition ratio of the first additive element Ti and the second additive element Zn, and further the high-capacity element Si is within the appropriate range specified above.
- An active material can be provided. Specifically, even in the case where the composition ratio of the Si—Ti—Zn alloy is within the range surrounded by the thick solid line in FIG.
- the Si alloy negative electrode having the best characteristics when the composition ratio of the first additive element Ti and the second additive element Zn, and further the high-capacity element Si is within the appropriate range specified above.
- An active material can be provided. Specifically, when the composition ratio of the Si—Ti—Zn alloy is within the range surrounded by the thick solid line in FIG. 9 (the inside of the small square), it is remarkably impossible with existing carbon-based negative electrode active materials. High capacity can be realized.
- the negative electrode active material is a ternary amorphous alloy represented by the composition formula Si x Ti y Zn z having the above-described appropriate composition ratio in a manufactured state (uncharged state).
- the initial capacity (discharge capacity at the first cycle) is much higher than the existing carbon-based negative electrode active material (theoretical capacity 372 mAh / g).
- the capacity is higher than that of the Sn-based negative electrode active material (theoretical capacity is about 600 to 700 mAh / g).
- the cycle characteristics are very poor and sufficient when compared with the discharge capacity retention ratio (about 60%) of the 50th cycle of the Sn-based negative electrode active material that can be increased in capacity to about 600 to 700 mAh / g. There wasn't. That is, the balance between the increase in capacity and the cycle durability, which are in a trade-off relationship, is poor and cannot be put into practical use.
- the alloy composition of patent document 1 is described by atomic ratio, when converted into mass ratio like this embodiment, about 20 mass% of Fe is contained in the Example, and it becomes a 1st addition element. It can be said that the alloy composition is disclosed.
- the negative electrode active material using the ternary alloy represented by Si x Ti y Zn z of the present embodiment has a high discharge capacity maintenance ratio at the 50th cycle as high cycle characteristics (see FIG. 4).
- the initial capacity (discharge capacity at the first cycle) is much higher than that of the existing carbon-based negative electrode active material, and is equal to or higher than that of the existing Sn-based negative electrode active material (see FIG. 3).
- the negative electrode active material shown can be provided.
- the existing carbon-based and Sn-based negative electrode active materials and the ternary and quaternary alloys described in Patent Document 1 have both high capacity and cycle durability characteristics that could not be realized due to a trade-off relationship.
- the present inventors have found a negative electrode active material using an alloy that can be balanced in a dimension. Specifically, two types of Ti and Zn are selected from the group consisting of one or two or more additive element species in which there are very various combinations, and these additive element species and the high-capacity element Si are further specified in a specific composition. It has been found that the intended purpose can be achieved by selecting the ratio (composition range). As a result, it is excellent in that a lithium ion secondary battery having a high capacity and good cycle durability can be provided.
- the range of x in the formula (2) which is the mass% value of Si in the alloy having the composition formula Si x Ti y Zn z , is 38 ⁇ x ⁇ 100.
- the high discharge capacity retention rate at the 50th cycle cannot be sufficiently maintained (see samples 13 to 24 in Table 1 and FIG. 4), and a great problem arises in that the cycle characteristics rapidly deteriorate (deteriorate).
- x 100 (in the case of pure Si containing no metal elements Ti and Zn added to Si)
- the increase in capacity and cycle durability are in a trade-off relationship, and high cycle durability while exhibiting high capacity. It can be seen that the property cannot be improved. That is, since it is only a high-capacity element Si, it has the highest capacity, but on the other hand, the deterioration as a negative electrode active material is remarkable due to the expansion and contraction phenomenon of Si accompanying charging and discharging, and the worst and extremely low discharge capacity is maintained. It can be seen that only a rate (only 47%) is obtained (see sample 19 in Table 1 and FIG. 4).
- a negative electrode which maintains a high cycle characteristic (particularly, a high discharge capacity maintenance ratio at the 50th cycle) and a high initial capacity in a well-balanced manner.
- a range of 38 ⁇ x ⁇ 72 is desirable.
- the composition ratio of Ti, which is the first additive element and Zn, which is the second additive element described later is appropriate, good characteristics (high capacity that is in a trade-off relationship with existing alloy-based negative electrode active materials) And a Si alloy negative electrode active material having excellent characteristics in both cycle durability (see Table 1 and Samples 1 to 12 of Example 1 in FIG. 7).
- the mass% value (x value) of the high-capacity element Si in the alloy is a negative electrode active material that maintains a high cycle characteristic (higher discharge capacity retention ratio) while maintaining a high initial capacity in a well-balanced manner. From the viewpoint of providing, it can be said that the range of 38 ⁇ x ⁇ 61 is more desirable.
- an Si alloy negative electrode active material having better characteristics can be provided (Table 1 and FIG. (Internal reference enclosed by 8 thick solid lines).
- a negative electrode active material that maintains a particularly high cycle characteristic (particularly a high discharge capacity retention ratio) and a high initial capacity in a well-balanced manner. From the viewpoint of providing, it can be said that the range of 47 ⁇ x ⁇ 53 is particularly desirable.
- a high-performance Si alloy negative electrode active material having the best characteristics can be provided (Table 1). 1 and the internal reference surrounded by the thick solid line in FIG. 9).
- the particularly preferable range of 47 ⁇ x ⁇ 53 is particularly excellent in that a high capacity (1129 mAh / g or more) and a particularly high discharge capacity maintenance rate (95% or more) in the 50th cycle can be maintained. (Internal reference enclosed in bold solid line in Table 1 and FIG. 9).
- the Si material (x value) having the initial capacity of 3200 mAh / g, the first additive element Ti (y value), and the second additive element Zn (z value) can be in an optimum range (see the range surrounded by the thick solid line in FIGS. 5 to 9). Therefore, it is excellent in that the most favorable characteristics can be expressed and the increase in capacity at the vehicle application level can be stably and safely maintained over a long period of time.
- the content ratio of the high capacity Si material having an initial capacity of 3200 mAh / g, the first additive element Ti, and the second additive element Zn (Balance) can be in an optimal range (see the range surrounded by the thick solid line in FIGS. 5 to 9). Therefore, when alloying Si and Li, the amorphous-crystal phase transition can be remarkably suppressed, and the cycle life can be greatly improved. That is, it is possible to achieve a discharge capacity maintenance ratio of 87% or more, particularly 90% or more, especially 96% or more in the 50th cycle.
- Patent Document 1 it is disclosed in the above-mentioned embodiment of Patent Document 1 that the degradation of cycle characteristics due to a considerable capacity reduction is already exhibited in only about 5 to 6 cycles. That is, in the example of Patent Document 1, the discharge capacity maintenance rate at the 5th to 6th cycles has already been reduced to 90 to 95%, and the discharge capacity maintenance rate at the 50th cycle has been reduced to almost 50 to 0%. It will be.
- the combination of the first additive element Ti and the second additive element Zn to the high-capacity Si material is in a mutually complementary relationship, so to speak, many trials and errors, and various additions (metal or nonmetal). It was possible to select through an excessive experiment with a combination of elements (only one combination).
- the content of the high-capacity Si material is within the optimum range shown above, it is excellent in that the capacity can be increased and the reduction in the discharge capacity maintenance ratio at the 50th cycle can be greatly reduced. . That is, when Si and Li are alloyed, the crystal is crystallized from an amorphous state due to a particularly remarkable synergistic effect (effect) due to the optimum range of the first additive element Ti and the second additive element Zn mutually complementary to Ti. The transition to the state can be suppressed, and a large volume change can be prevented. Furthermore, it is also excellent in that the high cycle durability of the electrode can be improved while showing a high capacity (see Table 1 and FIGS. 5 to 9).
- the range of y in the formula (3) which is the mass% value of Ti in the alloy having the composition formula Si x Ti y Zn z , is 0 ⁇ y ⁇ 62.
- the content x value of the high-capacity Si material can be maintained at a certain level (38 ⁇ x ⁇ 100), and the existing carbon-based negative electrode active It is possible to achieve an extremely high capacity that cannot be realized by using a material, and to obtain an alloy having a higher capacity (initial capacity of 690 mAh / g or more) than that of an existing Sn-based alloy negative electrode active material. Yes (see Table 1 and FIG. 5).
- the mass% value (y value) of the first additive element Ti in the alloy is preferably a good balance between the characteristics with a high initial capacity while maintaining a high cycle characteristic (particularly a high discharge capacity retention rate at the 50th cycle). From the viewpoint of providing the negative electrode active material shown, a range of 0 ⁇ y ⁇ 42 is desirable. When the content ratio of the first additive element Ti having an effect of suppressing the amorphous-crystal phase transition and improving the cycle life is appropriate at the time of forming the Li alloy, an Si alloy negative electrode active material having good characteristics is obtained. (See Table 1 and the composition range surrounded by the thick solid line in FIG. 6).
- the cycle life of the amorphous-crystal phase transition is suppressed during alloying.
- This is preferable in that the effect of improving the discharge capacity can be effectively expressed, and a high discharge capacity retention rate (87% or more) at the 50th cycle can be maintained (see Table 1 and FIG. 6).
- a composition range in particular, 0 ⁇ y ⁇ 42 with respect to the Ti content
- high capacity could be realized in the samples 1 to 12 of Example 1 was selected (enclosed by the thick solid line in FIG. 6).
- a pentagon A pentagon).
- the cycle durability is far superior to Sn-based negative electrode active materials and multi-component alloy negative electrode active materials described in Patent Document 1.
- a Si alloy negative electrode active material realizing a discharge capacity retention rate of 87% or more can be provided (see Table 1 and FIG. 6).
- the mass% value (y value) of the first additive element Ti in the alloy shows a high balance of the characteristics with high initial capacity while maintaining high cycle characteristics (high discharge capacity retention ratio at the 50th cycle). From the viewpoint of providing the negative electrode active material, it can be said that the range of 8 ⁇ y ⁇ 42 is desirable.
- the content ratio of the first additive element Ti having an effect of suppressing the amorphous-crystal phase transition and improving the cycle life is appropriate at the time of forming the Li alloy, an Si alloy negative electrode active material having good characteristics is obtained. (See Table 1 and FIG. 7).
- the capacity is increased and it is markedly superior to the Sn-based negative electrode active material and the multi-component alloy negative electrode active material described in Patent Document 1.
- the mass% value (y value) of the first additive element Ti in the alloy while maintaining higher cycle characteristics (high discharge capacity retention rate at the 50th cycle), the characteristics of the initial capacity are also very high. From the viewpoint of providing a negative electrode active material that is well-balanced, a range of 19 ⁇ y ⁇ 42 is desirable.
- the content ratio of the first additive element Ti which has the effect of suppressing the amorphous-crystal phase transition and improving the cycle life, is more appropriate when forming the Li alloy, the Si alloy negative electrode active material having even better characteristics can be obtained. Substances can be provided (see Table 1 and FIG. 8).
- the mass% value (y value) of the first additive element Ti in the alloy is preferably the highest balance between the characteristics with high initial capacity while maintaining higher cycle characteristics (high discharge capacity retention rate at the 50th cycle).
- the range of 19 ⁇ y ⁇ 21 is desirable from the viewpoint of providing a well-shown negative electrode active material.
- the Si alloy negative electrode active material having the best characteristics is most suitable. Substances can be provided (see Table 1 and FIG. 9).
- the negative electrode active material (negative electrode) is excellent in that it can exhibit the best characteristics and can maintain a high capacity at the vehicle application level stably and safely over a long period of time.
- the inclusion of a high-capacity Si material having an initial capacity of about 3200 mAh / g and the first additive element Ti (and also the second additive element Zn) The ratio (balance) can be in an optimum range (see the range surrounded by the thick solid line in FIGS. 6 to 9). Therefore, when alloying Si and Li, the amorphous-crystal phase transition can be remarkably suppressed, and the cycle life can be greatly improved.
- Patent Document 1 it is disclosed in the above-mentioned embodiment of Patent Document 1 that the degradation of cycle characteristics due to a considerable capacity reduction is already exhibited in only about 5 to 6 cycles. That is, in the example of Patent Document 1, the discharge capacity maintenance rate at the 5th to 6th cycles has already been reduced to 90 to 95%, and the discharge capacity maintenance rate at the 50th cycle has been reduced to almost 50 to 0%. It will be.
- the first additive element Ti and the combination of the second additive element Zn, which is a mutually complementary relationship
- the high-capacity Si material a number of trials and errors, and various additions ( It can be selected through undue experimentation with combinations of elements (metal or non-metal) (only one combination).
- the range of z in the formula (4) which is the mass% value of Zn in the alloy having the composition formula Si x Ti y Zn z , is 0 ⁇ z ⁇ 62.
- 0 ⁇ z ⁇ 39 more preferably 12 ⁇ z ⁇ 39, particularly preferably 12 ⁇ z ⁇ 35, and particularly preferably 26 ⁇ z ⁇ 35. This is because, when the concentration of the first additive element in the alloy increases, the capacity as an electrode does not decrease, and the mass% value (z value) of the second additive element species Zn is in the range of 0 ⁇ z ⁇ 62.
- the amorphous-crystal phase transition of the high-capacity Si material can be effectively suppressed.
- an effect excellent in cycle life (cycle durability), in particular, a high discharge capacity retention rate (87% or more) at the 50th cycle can be expressed (see Table 1 and FIG. 5).
- the content x value of the high-capacity Si material can be maintained at a certain value (38 ⁇ x ⁇ 100), and the capacity can be significantly increased as compared with existing carbon-based negative electrode active materials.
- a high-capacity alloy equivalent to or higher than the negative electrode active material can be obtained (see FIG. 5).
- a binary alloy that does not contain any one of the additive metal elements (Ti, Zn) to Si of the ternary alloy represented by the composition formula Si x Ti y Zn z (particularly, z 0)
- Si—Ti alloy high cycle characteristics cannot be maintained as compared with the present embodiment.
- the high discharge capacity maintenance rate at the 50th cycle cannot be sufficiently maintained (see samples 13 to 25 in Table 1 and FIG. 4), and there is a serious problem that the cycle characteristics are rapidly deteriorated (deteriorated).
- Zn does not function as an active material, alloying of Zn and Li is difficult, characteristics as a negative electrode active material cannot be sufficiently exhibited, and high capacity is also cycled. It is extremely difficult to develop durability.
- the mass% value (z value) of the second additive element Zn in the alloy preferably maintains a high cycle characteristic (particularly, a high discharge capacity retention rate at the 50th cycle) and a high initial capacity characteristic in a well-balanced manner.
- a range of 0 ⁇ z ⁇ 39 is desirable.
- the capacity of the first additive element Ti which suppresses the amorphous-crystal phase transition and improves the cycle life, and the negative electrode active material (negative electrode) does not decrease even when the concentration of the first additive element increases. Selection of the second additive element Zn is extremely important and useful in the present embodiment.
- first and second additive elements With such first and second additive elements, a known ternary alloy, a quaternary or higher alloy such as Patent Document 1, and a binary alloy such as a Si—Ti alloy or a Si—Zn alloy can be used. It was found that there was a significant difference in action and effect. When the content ratio of the second additive element Zn (and the first additive element Ti mutually complementary with Zn) is appropriate, the Si alloy negative electrode active material having good characteristics is obtained (Table 1 and FIG. 6). (See composition range surrounded by thick solid line).
- a pentagon By selecting 0 ⁇ y ⁇ 39 with respect to the composition range, particularly Zn content, a Sn-based negative electrode active material or a multi-element system described in Patent Document 1 can be obtained due to a synergistic effect (mutual complementary characteristics) with the first additive element Ti. Compared with an alloy negative electrode active material, it is possible to realize a cycle durability that is remarkably superior. As a result, it is possible to provide a Si alloy negative electrode active material that achieves a discharge capacity retention ratio of 87% or more at the 50th cycle (see Table 1 and the composition range surrounded by a thick solid line in FIG. 6).
- the mass% value (z value) of the second additive element Zn in the alloy balances the characteristics with high initial capacity while maintaining high cycle characteristics due to the synergistic effect (mutual complementary characteristics) with the first additive element Ti.
- z value mass% value
- the mass% value (z value) of the second additive element Zn in the alloy balances the characteristics with high initial capacity while maintaining high cycle characteristics due to the synergistic effect (mutual complementary characteristics) with the first additive element Ti.
- a range of 12 ⁇ z ⁇ 39 is desirable.
- Good when the content ratio of the second additive element Zn is appropriate, which can achieve the effect of suppressing the amorphous-crystal phase transition and improving the cycle life by synergistic effect (mutual complementarity) with Ti during Li alloying This is because a Si alloy negative electrode active material having excellent characteristics can be provided.
- the effect of suppressing the amorphous-crystal phase transition and improving the cycle life when alloying due to the synergistic effect (mutual complementarity characteristic) with the first additive element. Can be effectively expressed.
- a high discharge capacity maintenance rate of 87% or more at the 50th cycle can be maintained (see Table 1 and FIG. 7).
- the composition range in which Samples 1 to 12 of Example 1 were able to achieve a high capacity and a high discharge capacity retention rate of 87% or more at the 50th cycle is selected (the hexagon surrounded by the thick solid line in FIG. 7).
- the capacity is increased by synergistic properties with Ti and compared with the Sn-based negative electrode active material and the multi-component alloy negative electrode active material described in Patent Document 1. Even in this case, it is possible to provide a Si alloy negative electrode active material that realizes remarkably excellent cycle durability.
- the mass% value (z value) of the second additive element Zn in the alloy has a very high initial capacity while maintaining a higher cycle characteristic (high discharge capacity retention rate at the 50th cycle). From the viewpoint of providing a negative electrode active material that is well-balanced, a range of 12 ⁇ z ⁇ 35 is desirable.
- the content ratio of the second additive element Zn which can exhibit the effect of suppressing the amorphous-crystal phase transition and improving the cycle life due to the synergistic effect (mutual complementary characteristics) with Ti, is more appropriate during Li alloying This is because a Si alloy negative electrode active material having even better characteristics can be provided.
- the effect of suppressing the amorphous-crystal phase transition and improving the cycle life is more effective when alloying due to the synergistic effect (mutual complementarity) with Ti. Can be expressed.
- a higher discharge capacity maintenance rate of 90% or more at the 50th cycle can be maintained (see Table 1 and FIG. 8).
- a composition range in which a high capacity and a high discharge capacity retention ratio of 50% or more at the 50th cycle could be realized is selected (small hexagons surrounded by thick solid lines in FIG. 8).
- the mass% value (z value) of the second additive element Zn in the alloy is preferably the highest balance between the characteristics with high initial capacity while maintaining higher cycle characteristics (high discharge capacity retention rate at the 50th cycle).
- the range of 26 ⁇ z ⁇ 35 is desirable from the viewpoint of providing a well-shown negative electrode active material.
- the content ratio (balance) of the high-capacity Si material having an initial capacity of 3200 mAh / g and the first additive element Ti and the further second additive element Zn. Can be the optimum range (see the range surrounded by the thick solid line in FIGS. 7 to 9). Therefore, even if the Ti concentration that can suppress the phase transition of amorphous-crystal, which is a characteristic of Zn (synergistic effect with Ti; mutual complementarity characteristics), increases the capacity as the negative electrode active material (negative electrode). Therefore, the cycle life (particularly the discharge capacity maintenance rate) can be significantly improved.
- the negative electrode active material (negative electrode) is excellent in that it can exhibit the best characteristics and can maintain a high capacity at the vehicle application level stably and safely over a long period of time.
- the content ratio (balance) of the high-capacity Si material having an initial capacity of 3200 mAh / g and the first additive element Ti and the second additive element Zn is optimal. It can be a range (see the range surrounded by the thick solid line in FIGS. 6 to 9).
- the amorphous-crystal phase transition can be remarkably suppressed, and the cycle life (especially the discharge capacity retention rate at the 50th cycle) can be greatly improved. That is, the discharge capacity maintenance rate at the 50th cycle can be 87% or more, particularly 90% or more, and particularly 96% or more.
- the discharge capacity maintenance rate at the 50th cycle can be 87% or more, particularly 90% or more, and particularly 96% or more.
- the above-described effects of the present embodiment are effectively expressed. Needless to say, it is included in the technical scope (right range) of the present invention as long as it can be performed.
- Patent Document 1 it is disclosed in the above-mentioned embodiment of Patent Document 1 that the degradation of cycle characteristics due to a considerable capacity reduction is already exhibited in only about 5 to 6 cycles. That is, in the example of Patent Document 1, the discharge capacity maintenance rate at the 5th to 6th cycles has already been reduced to 90 to 95%, and the discharge capacity maintenance rate at the 50th cycle has been reduced to almost 50 to 0%. It will be.
- the combination of the first additive element Ti and the second additive element Zn to the high-capacity Si material is in a mutually complementary relationship. It can be selected through an excessive experiment with combinations of elemental species (only one combination).
- the reduction of the discharge capacity maintenance ratio at the 50th cycle can be greatly reduced by further making the Zn content within the optimum range shown above. That is, when Si and Li are alloyed, the crystal is crystallized from an amorphous state by a particularly remarkable synergistic effect (effect) due to the optimum range of the second additive element Zn (and the first additive element Ti mutually complementary to Zn). The transition to the state can be suppressed, and a large volume change can be prevented. Furthermore, it is also excellent in that the high cycle durability of the electrode can be improved while exhibiting a high capacity.
- the composition formula of the alloy having a z Si x Ti y Zn z is not limited in particular, the production of conventionally known various It can be manufactured using. That is, since there is almost no difference in the alloy state and characteristics depending on the production method, various production methods can be applied.
- a method for producing a thin film form of an alloy having the composition formula Si x Ti y Zn z includes, for example, a multi-element PVD method (a sputtering method (a method adopted in the examples), a resistance heating method, a laser, Ablation method), multi-source CVD method (chemical vapor deposition method) and the like can be used.
- a method for producing a particulate form of alloys with (ii) the composition formula Si x Ti y Zn z for example, it can be utilized mechanical alloy method, the arc plasma melting method or the like.
- the method for producing the alloy thin film of (i) for example, as a multi-element DC magnetron sputtering apparatus, an independently controlled ternary DC magnetron sputtering apparatus is used, and various alloy compositions and thicknesses are formed on the substrate (current collector) surface.
- a Si x Ti y Zn z alloy thin film can be freely formed.
- target 1 Si
- target 2 Ti
- target 3 Zn
- sputtering time is fixed, and the power of the DC power source is changed to obtain various alloy samples (specifically, implementation) (See Samples 1-25 in Example 1).
- ternary alloy samples having various composition formulas can be obtained by changing the power of the DC power source such as Si: 185 W, Ti: 50 W, and Zn: 50 W, respectively.
- the sputtering conditions are different for each sputtering apparatus, it is desirable to grasp a suitable range for the sputtering conditions through preliminary experiments as appropriate for each sputtering apparatus. Specifically, see the sputtering conditions, target specifications, and electrode sample specifications in the sputtering apparatus shown in Example 1.
- a suitable range of the power of the DC power source when the sputtering time is fixed as the sputtering conditions, target specifications, and electrode sample specifications in the sputtering apparatus shown in Example 1 is as described on the left.
- preferable ranges of the power of the DC power source are Si: 185 W, Ti: 50 to 200 W, and Zn: 30 to 90 W. With such a range, the alloy having the above composition formula Si x Ti y Zn z in an amorphous state can be produced in the form of thin films.
- these values are only suitable ranges (reference values) under the sputtering conditions, target specifications, and electrode sample specifications in the sputtering apparatus shown in the first embodiment, and are different for each sputtering apparatus as described above. Therefore, it is desirable that the suitable ranges of the sputtering conditions, target specifications, electrode sample specifications, and the like are appropriately determined through preliminary experiments for each sputtering apparatus.
- a slurry in the method for producing particles in the form (ii), a slurry can be prepared by adding a binder, a conductive additive and a viscosity adjusting solvent to the particles, and a slurry electrode can be formed using the slurry. Therefore, compared with the above (i), it is easy to mass-produce (mass production) and is excellent in that it can be put into practical use as an actual battery electrode. In addition, since the influence of a binder and a conductive support agent is large, it can be said that the above (i) is more suitable for viewing the characteristics of the active material.
- the average particle diameter of the alloy is the negative electrode included in the existing negative electrode active material layer 15.
- the average particle diameter of the alloy is the negative electrode included in the existing negative electrode active material layer 15.
- it is preferably in the range of 1 to 20 ⁇ m.
- it is not limited at all to the above range, and it goes without saying that it may be outside the above range as long as the effects of the present embodiment can be effectively expressed.
- the positive electrode active material layer 13 and the negative electrode active material layer 15 in the case of using the alloy in the form of the particles of (5) (ii) above include a binder.
- a binder used for an active material layer For example, the following materials are mentioned. Polyethylene, polypropylene, polyethylene terephthalate (PET), polyether nitrile (PEN), polyacrylonitrile, polyimide, polyamide, cellulose, carboxymethyl cellulose (CMC), ethylene-vinyl acetate copolymer, polyvinyl chloride, styrene-butadiene rubber (SBR) ), Isoprene rubber, butadiene rubber, ethylene / propylene rubber, ethylene / propylene / diene copolymer, styrene / butadiene / styrene block copolymer and hydrogenated product thereof, styrene / isoprene / styrene block copolymer and hydrogenated product thereof
- Thermoplastic polymers such as products, polyvinylidene fluoride (PVdF), polytetrafluoroethylene
- polyvinylidene fluoride, polyimide, styrene / butadiene rubber, carboxymethyl cellulose, polypropylene, polytetrafluoroethylene, polyacrylonitrile, and polyamide are more preferable.
- These suitable binders are excellent in heat resistance, have a very wide potential window, are stable at both the positive electrode potential and the negative electrode potential, and can be used for the active material layer. These binders may be used alone or in combination of two.
- the amount of the binder contained in the active material layer is not particularly limited as long as it is an amount capable of binding the active material, but is preferably 0.5 to 15% by mass with respect to the active material layer. More preferably, it is 1 to 10% by mass.
- additives examples include a conductive additive, an electrolyte salt (lithium salt), and an ion conductive polymer.
- the conductive assistant means an additive blended to improve the conductivity of the positive electrode active material layer or the negative electrode active material layer.
- Examples of the conductive assistant include carbon materials such as carbon black such as acetylene black, graphite, and vapor grown carbon fiber.
- the conductive binder having the functions of the conductive assistant and the binder may be used in place of the conductive assistant and the binder, or may be used in combination with one or both of the conductive assistant and the binder.
- Commercially available TAB-2 (manufactured by Hosen Co., Ltd.) can be used as the conductive binder.
- electrolyte salt examples include Li (C 2 F 5 SO 2 ) 2 N, LiPF 6 , LiBF 4 , LiClO 4 , LiAsF 6 , LiCF 3 SO 3 and the like.
- Examples of the ion conductive polymer include polyethylene oxide (PEO) and polypropylene oxide (PPO) polymers.
- the compounding ratio of the components contained in the negative electrode active material layer in the case of using the positive electrode active material layer and the alloy in the form of particles of (5) (ii) above is not particularly limited.
- the mixing ratio can be adjusted by appropriately referring to known knowledge about the non-aqueous solvent secondary battery.
- each active material layer (active material layer on one side of the current collector) is not particularly limited, and conventionally known knowledge about the battery can be appropriately referred to.
- the thickness of each active material layer is usually about 1 to 500 ⁇ m, preferably 2 to 100 ⁇ m, taking into consideration the intended use of the battery (emphasis on output, energy, etc.) and ion conductivity.
- the current collectors 11 and 12 are made of a conductive material.
- the size of the current collector is determined according to the intended use of the battery. For example, if it is used for a large battery that requires a high energy density, a current collector having a large area is used.
- the thickness of the current collector is usually about 1 to 100 ⁇ m.
- the shape of the current collector is not particularly limited. In the laminated battery 10 shown in FIG. 1, in addition to the current collector foil, a mesh shape (such as an expanded grid) can be used.
- a mesh shape such as an expanded grid
- a metal or a resin in which a conductive filler is added to a conductive polymer material or a non-conductive polymer material can be employed.
- the metal include aluminum, nickel, iron, stainless steel, titanium, and copper.
- a clad material of nickel and aluminum, a clad material of copper and aluminum, or a plating material of a combination of these metals can be preferably used.
- covered on the metal surface may be sufficient.
- aluminum, stainless steel, copper, and nickel are preferable from the viewpoints of electronic conductivity, battery operating potential, and adhesion of the negative electrode active material by sputtering to the current collector.
- examples of the conductive polymer material include polyaniline, polypyrrole, polythiophene, polyacetylene, polyparaphenylene, polyphenylene vinylene, polyacrylonitrile, and polyoxadiazole. Since such a conductive polymer material has sufficient conductivity without adding a conductive filler, it is advantageous in terms of facilitating the manufacturing process or reducing the weight of the current collector.
- Non-conductive polymer materials include, for example, polyethylene (PE; high density polyethylene (HDPE), low density polyethylene (LDPE), etc.), polypropylene (PP), polyethylene terephthalate (PET), polyether nitrile (PEN), polyimide (PI), polyamideimide (PAI), polyamide (PA), polytetrafluoroethylene (PTFE), styrene-butadiene rubber (SBR), polyacrylonitrile (PAN), polymethyl acrylate (PMA), polymethyl methacrylate (PMMA) , Polyvinyl chloride (PVC), polyvinylidene fluoride (PVdF), or polystyrene (PS).
- PE polyethylene
- HDPE high density polyethylene
- LDPE low density polyethylene
- PP polypropylene
- PET polyethylene terephthalate
- PEN polyether nitrile
- PI polyimide
- PAI polyamideimide
- PA polyamide
- PTFE polytetraflu
- a conductive filler may be added to the conductive polymer material or the non-conductive polymer material as necessary.
- a conductive filler is inevitably necessary to impart conductivity to the resin.
- the conductive filler can be used without particular limitation as long as it is a substance having conductivity.
- metals, conductive carbon, etc. are mentioned as a material excellent in electroconductivity, electric potential resistance, or lithium ion barrier
- the metal is not particularly limited, but at least one metal selected from the group consisting of Ni, Ti, Al, Cu, Pt, Fe, Cr, Sn, Zn, In, Sb, and K, or these metals It is preferable to contain an alloy or metal oxide containing. Moreover, there is no restriction
- the amount of the conductive filler added is not particularly limited as long as it is an amount capable of imparting sufficient conductivity to the current collector, and is generally about 5 to 35% by mass.
- a liquid electrolyte or a polymer electrolyte can be used as the electrolyte constituting the electrolyte layer 17.
- the liquid electrolyte has a form in which a lithium salt as a supporting salt is dissolved in an organic solvent as a plasticizer.
- organic solvent examples include carbonates such as ethylene carbonate (EC), propylene carbonate (PC), diethyl carbonate (DEC), and dimethyl carbonate (DMC).
- the supporting salt lithium salt
- a compound that can be added to the active material layer of the electrode such as LiBETI, can be similarly employed.
- polymer electrolytes are classified into gel electrolytes containing an electrolytic solution and intrinsic polymer electrolytes not containing an electrolytic solution.
- the gel electrolyte has a configuration in which the above liquid electrolyte (electrolytic solution) is injected into a matrix polymer made of an ion conductive polymer.
- the ion conductive polymer used as the matrix polymer include polyethylene oxide (PEO), polypropylene oxide (PPO), and copolymers thereof.
- electrolyte salts such as lithium salts can be well dissolved.
- the ratio of the liquid electrolyte (electrolytic solution) in the gel electrolyte is not particularly limited, but is preferably about several mass% to 98 mass% from the viewpoint of ionic conductivity.
- the gel electrolyte having a large amount of electrolytic solution having a ratio of the electrolytic solution of 70% by mass or more is particularly effective.
- a separator may be used for the electrolyte layer.
- the separator include a microporous film made of polyolefin such as polyethylene and polypropylene, a porous flat plate, and a non-woven fabric.
- the intrinsic polymer electrolyte has a structure in which a supporting salt (lithium salt) is dissolved in the above matrix polymer, and does not contain an organic solvent that is a plasticizer. Therefore, when the electrolyte layer is composed of an intrinsic polymer electrolyte, there is no fear of liquid leakage from the battery, and the reliability of the battery can be improved.
- a supporting salt lithium salt
- the matrix polymer of the gel electrolyte or the intrinsic polymer electrolyte can express excellent mechanical strength by forming a crosslinked structure.
- thermal polymerization, ultraviolet polymerization, radiation polymerization, electron beam polymerization, etc. are performed on a polymerizable polymer (for example, PEO or PPO) for forming a polymer electrolyte using an appropriate polymerization initiator.
- a polymerization treatment may be performed.
- a current collecting plate may be used for the purpose of taking out the current outside the battery.
- the current collector plate is electrically connected to the current collector and the lead, and is taken out of the laminate sheet that is a battery exterior material.
- the material constituting the current collector plate is not particularly limited, and a known highly conductive material conventionally used as a current collector plate for a lithium ion secondary battery can be used.
- a constituent material of the current collector plate for example, metal materials such as aluminum, copper, titanium, nickel, stainless steel (SUS), and alloys thereof are preferable, and aluminum is more preferable from the viewpoint of light weight, corrosion resistance, and high conductivity. Copper or the like is preferable. Note that the same material may be used for the positive electrode current collector plate and the negative electrode current collector plate, or different materials may be used.
- ⁇ Use positive terminal lead and negative terminal lead as required.
- a terminal lead used in a known lithium ion secondary battery can be used.
- the part taken out from the battery outer packaging material 29 has a heat insulating property so as not to affect the product (for example, automobile parts, particularly electronic devices) by contacting with peripheral devices or wiring and causing leakage. It is preferable to coat with a heat shrinkable tube or the like.
- Battery exterior material As the battery exterior material 29, a known metal can case can be used, and a bag-like case using a laminate film containing aluminum that can cover the power generation element can be used.
- a laminate film having a three-layer structure in which PP, aluminum, and nylon are laminated in this order can be used as the laminate film, but the laminate film is not limited thereto.
- a laminate film is desirable from the viewpoint that it is excellent in high output and cooling performance, and can be suitably used for a battery for large equipment for EV and HEV.
- said lithium ion secondary battery can be manufactured with a conventionally well-known manufacturing method.
- FIG. 2 is a perspective view showing the appearance of a stacked flat lithium ion secondary battery.
- the stacked flat lithium ion secondary battery 50 has a rectangular flat shape, and a positive current collector 58 for taking out power from both sides thereof, a negative current collector, and the like.
- the electric plate 59 is pulled out.
- the power generation element 57 is wrapped by the battery outer packaging material 52 of the lithium ion secondary battery 50, and the periphery thereof is heat-sealed.
- the power generation element 57 pulls out the positive electrode current collector plate 58 and the negative electrode current collector plate 59 to the outside. Sealed.
- the power generation element 57 corresponds to the power generation element 21 of the lithium ion secondary battery (stacked battery) 10 shown in FIG.
- the power generation element 57 is formed by laminating a plurality of single battery layers (single cells) 19 including a positive electrode (positive electrode active material layer) 13, an electrolyte layer 17, and a negative electrode (negative electrode active material layer) 15.
- the lithium ion secondary battery is not limited to a laminated flat shape (laminate cell).
- a cylindrical shape coin cell
- a prismatic shape square cell
- it may be a cylindrical cell, and is not particularly limited.
- the cylindrical or prismatic shape is not particularly limited, for example, a laminate film or a conventional cylindrical can (metal can) may be used as the exterior material.
- the power generation element is covered with an aluminum laminate film. With this configuration, weight reduction can be achieved.
- the removal of the positive electrode current collector plate 58 and the negative electrode current collector plate 59 shown in FIG. 2 is not particularly limited.
- the positive electrode current collector plate 58 and the negative electrode current collector plate 59 may be drawn from the same side, or the positive electrode current collector plate 58 and the negative electrode current collector plate 59 may be divided into a plurality of parts and taken out from each side. It is not limited to the one shown in FIG.
- a terminal instead of the current collector plate, for example, a terminal may be formed using a cylindrical can (metal can).
- the negative electrode and the lithium ion secondary battery using the negative electrode active material for the lithium ion secondary battery of the present embodiment are large vehicles such as electric vehicles, hybrid electric vehicles, fuel cell vehicles, and hybrid fuel cell vehicles. It can be suitably used as a capacity power source. That is, it can be suitably used for a vehicle driving power source and an auxiliary power source that require high volume energy density and high volume output density.
- the lithium ion battery is exemplified as the electric device.
- the present invention is not limited to this, and can be applied to other types of secondary batteries and further to primary batteries. It can also be applied to capacitors as well as batteries.
- Example 1 Samples 1 to 25
- Production of Evaluation Cell (1) Production of Evaluation Electrode Thin film alloys having various alloy compositions obtained by sputtering were used for the evaluation electrode.
- an independently controlled ternary DC magnetron sputtering apparatus (Daiwa Kikai Kogyo Co., Ltd., combinatorial sputter coating apparatus: gun-sample distance: about 100 mm) was used as the sputtering apparatus.
- a ternary DC magnetron sputtering apparatus (Daiwa Kikai Kogyo Co., Ltd., combinatorial sputter coating apparatus: gun-sample distance: about 100 mm) was used as the sputtering apparatus.
- thin film alloys (samples 1 to 25) having various alloy compositions were obtained under the following sputtering conditions, target specifications, and electrode sample specifications.
- Si target (4N) 2 inches in diameter, 3 mm thick + oxygen-free copper backing plate, 2 mm thick
- Zn target (4N) 2 inches in diameter and 5 mm in thickness.
- the analysis of the obtained alloy samples 1 to 25 was performed using the following analysis method and analyzer.
- the counter electrode includes a positive electrode slurry electrode (for example, LiCoO 2 , LiNiO 2 , LiMn 2 O 4 , Li (Ni, Mn, Co) O 2 , Li (Li, Ni, Mn, Co) O 2 , LiRO 2 ⁇ .
- an evaluation cell (CR2032 type coin cell) was constructed by combining the evaluation electrode with a Li foil (counter electrode), a separator, and an electrolytic solution.
- Charge / Discharge Test Conditions / Evaluation Method (1) Charge / Discharge Test Conditions (i) The charge / discharge test conditions of the evaluation cell were as follows.
- the evaluation cell is in a constant current / constant voltage mode in the charging process (referring to the Li insertion process to the evaluation electrode) in a thermostat set to the above evaluation temperature using a charge / discharge tester.
- the battery was charged from 2 V to 10 mV at 0.1 mA.
- a discharge process referring to a Li desorption process from the electrode for evaluation
- a constant current mode was set and discharge was performed from 0.1 mA, 10 mV to 2 V.
- the charge / discharge test was conducted from the initial cycle (1 cycle) to 50 cycles under the same charge / discharge conditions with the above charge / discharge cycle as one cycle.
- (2) Evaluation method The charge / discharge capacity was calculated per alloy weight.
- discharge capacity (mAh / g) in the table is based on the weight of pure Si or alloy, Li to Si—Ti—Zn alloy (Si—Zn alloy, pure Si or Si—Ti alloy). Indicates the capacity when reacts. In addition, what is described as “initial capacity” in the specification corresponds to “discharge capacity (mAh / g)” of the initial cycle (first cycle).
- discharge capacity maintenance ratio (%) at the 50th cycle in the table represents an index of “how much capacity is maintained from the initial capacity”. The calculation formula of the discharge capacity retention rate (%) is as follows.
- the initial capacity (the discharge capacity at the first cycle) is much higher than can be achieved with existing carbon-based negative electrode active materials (carbon / graphite-based negative electrode materials). It was confirmed that capacity could be realized. Similarly, it was confirmed that a higher capacity (initial capacity of 690 mAh / g or more) than that of the existing Sn-based alloy negative electrode active material can be realized. Furthermore, the cycle durability, which is in a trade-off relationship with the increase in capacity, is also compared with the existing Sn-based negative electrode active material having a high capacity but inferior in cycle durability and the multi-component alloy negative electrode active material described in Patent Document 1. However, it has been confirmed that the cycle durability can be remarkably improved.
- the cycle durability excellent at a high discharge capacity retention rate of 87% or more, preferably 90% or more, more preferably 96% or more at the 50th cycle can be realized. Therefore, the batteries of Samples 1 to 12 have a higher discharge capacity maintenance ratio at the 50th cycle than the batteries of Samples 13 to 25, and the high capacity can be maintained more efficiently by suppressing the decrease in the high initial capacity. I found out.
- the first additive element Ti that suppresses the amorphous-crystal phase transition and improves the cycle life, and the capacity as the electrode increases even when the concentration of the first additive element increases. It has been found that the selection of the second additive element species Zn that does not decrease is extremely useful and effective. By selecting the first and second additive elements, a Si alloy-based negative electrode active material having high capacity and high cycle durability can be provided. As a result, it was found that a lithium ion secondary battery with high capacity and good cycle durability can be provided.
- the reference batteries of Samples 13 to 25 can achieve a high capacity, it has been found that the discharge capacity maintenance rate is not sufficient at 47 to 85% for the cycle durability that is in a trade-off relationship with the high capacity. . From this, it was found that the reference battery could not sufficiently suppress the decrease (deterioration) in cycle durability. In other words, it was confirmed that none of the Si metals or binary alloys of Samples 13 to 25 could exhibit a trade-off relationship between high capacity and cycle durability in a well-balanced manner.
- Example 2 For the evaluation cell (CR2032 type coin cell) using the evaluation electrodes of Samples 4, 19, and 22, the initial cycle was performed under the same charge / discharge conditions as in Example 1.
- FIG. 10 shows a dQ / dV curve with respect to voltage (V) in the discharge process of the initial cycle.
- a sharp peak protruding downward in the vicinity of 0.4 V of sample 19 indicates a change due to the decomposition of the electrolytic solution.
- the downwardly convex gentle peaks in the vicinity of 0.35 V, 0.2 V, and 0.05 V are changed from the amorphous state to the crystallized state, respectively.
- Sample 4 Si—Ti—Zn ternary alloy thin film
- Sample 22 Si—Ti binary alloy thin film to which elements (Ti, Zn) other than Si were added were 2.5 V and 2.5 V, respectively.
- a downward and sharp peak indicating a change due to decomposition of the electrolytic solution was confirmed.
- there was no gentle downward peak that showed a change from the amorphous state to the crystallized state, and it was confirmed that the crystallization of the Li—Si alloy could be suppressed.
- Table 1 that the Si—Ti binary alloy thin film of Sample 22 could not be suppressed until the discharge capacity retention rate (%) decreased (deteriorated) after 50 cycles.
- the ternary alloy of this example exhibits high cycle characteristics, in particular, high discharge capacity maintenance ratio at the 50th cycle, and high discharge capacity at the first cycle and high balance characteristics.
- the mechanism (action mechanism) can be estimated (estimated) as follows.
- Example 2 when the dQ / dV curve of the ternary alloy is observed, the peak in the low potential region ( ⁇ 0.6 V) is less than that of pure-Si that is not an alloy and is smooth. . This seems to mean that the decomposition of the electrolytic solution is suppressed and further that the phase transition of the Li—Si alloy to the crystal phase is suppressed (see FIG. 10).
- Lithium ion secondary battery (stacked battery), 11 positive electrode current collector, 12 negative electrode current collector, 13 positive electrode active material layer, 15 negative electrode active material layer, 17 electrolyte layer, 19 cell layer, 21, 57 power generation element, 25, 58 positive current collector, 27, 59 negative electrode current collector plate, 29, 52 Battery exterior material (laminate film).
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Abstract
Description
図1は、本発明の電気デバイスの代表的な一実施形態である、扁平型(積層型)のリチウムイオン二次電池(以下、単に「積層型電池」ともいう)の全体構造を模式的に表した断面概略図である。
活物質層13または15は活物質を含み、必要に応じてその他の添加剤をさらに含む。
正極活物質層13は、正極活物質を含む。
正極活物質としては、例えば、リチウム-遷移金属複合酸化物、リチウム-遷移金属リン酸化合物、リチウム-遷移金属硫酸化合物、固溶体系、3元系、NiMn系、NiCo系、スピネルMn系などが挙げられる。リチウム-遷移金属複合酸化物としては、例えば、LiMn2O4、LiCoO2、LiNiO2、Li(Ni、Mn、Co)O2、Li(Li、Ni、Mn、Co)O2、LiFePO4及びこれらの遷移金属の一部が他の元素により置換されたもの等が挙げられる。固溶体系としては、xLiMO2・(1-x)Li2NO3(0<x<1、Mは平均酸化状態が3+、Nは平均酸化状態が4+である1種類以上の遷移金属)、LiRO2-LiMn2O4(R=Ni、Mn、Co、Fe等の遷移金属元素)等が挙げられる。3元系としては、ニッケル・コバルト・マンガン系(複合)正極材等が挙げられる。スピネルMn系としてはLiMn2O4等が挙げられる。NiMn系としては、LiNi0.5Mn1.5O4等が挙げられる。NiCo系としては、Li(NiCo)O2等が挙げられる。場合によっては、2種以上の正極活物質が併用されてもよい。好ましくは、容量、出力特性の観点から、リチウム-遷移金属複合酸化物が、正極活物質として用いられる。なお、上記以外の正極活物質が用いられてもよいことは勿論である。活物質それぞれの固有の効果を発現する上で最適な粒径が異なる場合には、それぞれの固有の効果を発現する上で最適な粒径同士をブレンドして用いればよく、全ての活物質の粒径を必ずしも均一化させる必要はない。
負極活物質層15は、本実施形態の組成式SixTiyZnzを有する合金を含む負極活物質を有するものである。本実施形態の負極活物質を用いることで、高容量・高サイクル耐久性を有する良好なリチウムイオン二次電池用負極となる。また、本実施形態の負極活物質を用いてなるリチウムイオン二次電池用負極を用いることで、高容量でサイクル耐久性に優れる良好な電池特性を有するリチウムイオン二次電池となる。
本実施形態では、負極活物質として、組成式SixTiyZnz(式中x、y、及びzは質量パーセント値を表し、(1)x+y+z=100であり、(2)38≦x<100であり、(3)0<y<62であり、(4)0<z<62である。)を有する合金を含むことを特徴とする。本実施形態では、Li合金化の際、アモルファス-結晶の相転移を抑制しサイクル寿命を向上させる第1添加元素Tiと、該第1添加元素濃度が増加しても電極としての容量が減少しない第2添加元素種Znを選定し、これら添加元素種と高容量元素Siを適切な組成比としてなるものである。ここでLi合金化の際、アモルファス-結晶の相転移を抑制するのは、Si材料ではSiとLiが合金化する際、アモルファス状態から結晶状態へ転移し大きな体積変化(約4倍)を起すため、粒子自体が壊れてしまい活物質としての機能が失われるためである。そのためアモルファス-結晶の相転移を抑制することで、粒子自体の崩壊を抑制し活物質としての機能(高容量)を保持することができ、サイクル寿命も向上させることができるものである。かかる第1及び第2添加元素を選定し、これら添加元素種と高容量元素Siを適切な組成比とすることにより、高容量で高サイクル耐久性を有するSi合金負極活物質を提供できる。具体的にはSi-Ti-Zn合金の組成比が図5の太い実線で囲われた範囲内(三角形の内側)の場合には、既存のカーボン系負極活物質では実現不可能な格段に高い高容量化を実現できる。同様に既存のSn系合金負極活物質と比較しても同様以上の高容量(初期容量690mAh/g以上)を実現できる。更に高容量化とトレードオフの関係にあるサイクル耐久性についても、高容量であるがサイクル耐久性の悪いSn系負極活物質や特許文献1に記載の多元系合金負極活物質と比較した場合には格段に優れたサイクル耐久性(特に、50サイクル目での高い放電容量維持率87%以上)を実現できるSi合金負極活物質を提供できる(表1及び図3、4、5参照のこと)。
上記組成式SixTiyZnzを有する合金の合計の質量%値である、式中(1)のx+y+z=100である(ここで、x、y、及びzは質量%値を表す)。即ち、Si-Ti-Zn系の3元系の合金からなるものでなければならない。言い換えれば、2元系の合金、他の組成の3元系の合金、或いは別の金属を添加した4元系以上の合金は含まれないものと言える。但し、製造上、不可避的に混入する極微量な不純物の金属元素等(本実施形態の作用効果に影響しない程度の極微量の金属元素等)については、含まれていてもよい。なお、本実施形態の負極活物質層15には、少なくとも1種の組成式SixTiyZnzを有する合金が含まれていればよく、2種以上の組成の異なる当該合金を併用して用いてもよい。
上記組成式SixTiyZnzを有する合金中のSiの質量%値である、式中(2)のxの範囲は、38≦x<100であり、好ましくは38≦x≦72であり、より好ましくは38≦x≦61であり、特に好ましくは47≦x≦53である(表1、図5~図9参照)。これは、合金中の高容量元素Siの質量パーセント値(x値)の数値が高いほど高容量化でき、38≦x<100の範囲であれば、既存のカーボン系負極活物質では実現不可能な格段に高い高容量(690mAh/g以上)を実現できるためである。同様に、既存のSn系負極活物質と同等以上の高容量の合金を得ることができるためである(図5及び6参照)。さらに38≦x<100の範囲であれば、50サイクル目の放電容量維持率(サイクル耐久性)にも優れるためである(表1、図4~6参照)。一方、組成式SixTiyZnzで表される3元系の合金に比して高容量元素Siへの添加金属元素(Ti、Zn)のいずれか一方を含まない2元系の合金(y=0のSi-Zn合金やz=0のSi-Ti系合金)では、高いサイクル特性を維持することができない。特に、50サイクル目の高い放電容量維持率を十分に維持することができず(表1のサンプル13~24及び図4参照)、サイクル特性が急激に低下(劣化)するという大きな問題が生じる。また、x=100の場合(Siへの添加金属元素Ti、Znを全く含まないpure Siの場合)、高容量化とサイクル耐久性はトレードオフの関係であり、高容量を示しつつ高サイクル耐久性を向上させることはできないことがわかる。即ち、高容量元素であるSiのみであるため、最も高容量である反面、充放電に伴いSiの膨脹収縮現象により、負極活物質としての劣化が顕著であり、最も悪く格段に低い放電容量維持率(僅か47%)しか得られないことがわかる(表1のサンプル19及び図4参照)。
上記組成式SixTiyZnzを有する合金中のTiの質量%値である、式中(3)のyの範囲は、0<y<62であり、好ましくは0<y≦42であり、より好ましくは8≦y≦42であり、特に好ましくは19≦y≦42、中でも好ましくは19≦y≦21である。これは、合金中の第1添加元素Tiの質量パーセント値(y値)の数値が0<y<62の範囲であれば、Tiの持つ特性(更にZnとの相乗特性により、高容量Si材料のアモルファス-結晶の相転移を効果的に抑制することができる。その結果、サイクル寿命(サイクル耐久性)、特に50サイクル目での高い放電容量維持率(87%以上)に優れた効果を発現することができる(表1、図5参照)。また、高容量Si材料の含有量x値の数値を一定以上(38≦x<100)に保持し得ることができ、既存のカーボン系負極活物質では実現不可能な格段に高い高容量化を実現できる。同様に既存のSn系合金負極活物質と比較しても同様以上の高容量(初期容量690mAh/g以上)の合金を得ることができる(表1及び図5参照)。一方、組成式SixTiyZnzで表される3元系の合金に対して高容量元素Siへの添加金属元素(Ti、Zn)のいずれか一方を含まない2元系の合金(特に、y=0のSi-Zn合金)では、本実施形態に比して高いサイクル特性を維持することができない。特に、50サイクル目の高い放電容量維持率を十分に維持することができず(表1のサンプル13~25及び図4参照)、サイクル特性が急激に低下(劣化)するという大きな問題が生じる。また、y≧62の場合、Tiは活物質としての働きはなく、TiとLiとの合金化が困難であり、活物質でないTi含有量が62質量%を超える場合には、負極活物質としての特性を十分に発現することができず、高い容量もサイクル耐久性も発現させることが極めて困難である。
上記組成式SixTiyZnzを有する合金中のZnの質量%値である、式中(4)のzの範囲は、0<z<62であり、好ましくは0<z≦39であり、より好ましくは12≦z≦39であり、特に好ましくは12≦z≦35であり、中でも好ましくは26≦z≦35である。これは、合金中の第1添加元素濃度が増加しても電極としての容量が減少しない第2添加元素種Znの質量%値(z値)の数値が0<z<62の範囲であれば、Tiの持つ特性とZnとの相乗特性により、高容量Si材料のアモルファス-結晶の相転移を効果的に抑制することができる。その結果、サイクル寿命(サイクル耐久性)、特に50サイクル目での高い放電容量維持率(87%以上)に優れた効果を発現することができる(表1、図5参照)。また、高容量Si材料の含有量x値の数値を一定以上(38≦x<100)に保持し得ることができ、既存のカーボン系負極活物質に比して格段に高容量化でき、Sn系負極活物質と同等以上の高容量の合金を得ることができる(図5参照)。一方、組成式SixTiyZnzで表される3元系の合金のSiへの添加金属元素(Ti、Zn)のいずれか一方を含まない2元系の合金(特に、z=0のSi-Ti合金)では、本実施形態に比して高いサイクル特性を維持することができない。特に、50サイクル目の高い放電容量維持率を十分に維持することができず(表1のサンプル13~25及び図4参照)、サイクル特性が急激に低下(劣化)するという大きな問題が生じる。また、z≧62の場合、Znは活物質としての働きはなく、ZnとLiとの合金化が困難であり、負極活物質としての特性を十分に発現することができず、高い容量もサイクル耐久性も発現させることが極めて困難である。
上記組成式SixTiyZnzを有する合金の製造方法としては、特に制限されるものではなく、従来公知の各種の製造を利用して製造することができる。即ち、作製方法による合金状態・特性の違いはほとんどないので、ありとあらゆる作製方法が適用できる。
で優れている。また、活物質の電気化学特性を調べるのに適している。
なお、上記(5)(ii)の粒子の形態の合金を用いる場合、該合金の平均粒子径は、既存の負極活物質層15に含まれる負極活物質の平均粒子径と同程度であればよく、特に制限されない。高出力化の観点からは、好ましくは1~20μmの範囲であればよい。ただし、上記範囲に何ら制限されるものではなく、本実施形態の作用効果を有効に発現できるものであれば、上記範囲を外れていてもよいことは言うまでもない。
以下に、正極及び負極活物質層13、15に共通する要件につき、説明する。
集電体11、12は導電性材料から構成される。集電体の大きさは、電池の使用用途に応じて決定される。例えば、高エネルギー密度が要求される大型の電池に用いられるのであれば、面積の大きな集電体が用いられる。集電体の厚さについても特に制限はない。集電体の厚さは、通常は1~100μm程度である。集電体の形状についても特に制限されない。図1に示す積層型電池10では、集電箔のほか、網目形状(エキスパンドグリッド等)等を用いることができる。なお、負極活物質をスパッタ法等により薄膜合金を負極集電体12上に直接形成する場合には、集電箔を用いるのが望ましい。
電解質層17を構成する電解質としては、液体電解質またはポリマー電解質が用いられうる。
電池外部に電流を取り出す目的で、集電板を用いてもよい。集電板は集電体やリードに電気的に接続され、電池外装材であるラミネートシートの外部に取り出される。
電池外装材29としては、公知の金属缶ケースを用いることができるほか、発電要素を覆うことができる、アルミニウムを含むラミネートフィルムを用いた袋状のケースが用いられうる。該ラミネートフィルムには、例えば、PP、アルミニウム、ナイロンをこの順に積層してなる3層構造のラミネートフィルム等を用いることができるが、これらに何ら制限されるものではない。高出力化や冷却性能に優れ、EV、HEV用の大型機器用電池に好適に利用することができるという観点から、ラミネートフィルムが望ましい。
図2は、積層型の扁平なリチウムイオン二次電池の外観を表した斜視図である。
1.評価用セルの作製
(1)評価用電極の作製
評価用電極にはスパッタ法により得られた種々の合金組成の薄膜合金を用いた。
2)スパッタガス種:Ar(99.9999%以上)
3)スパッタガス導入量:10sccm
4)スパッタ圧力:30mTorr
5)DC電源:Si(185W)、Ti(50~200W)、Zn(30~90W)
6)プレスパッタ時間:1min.
7)スパッタ時間:10min.
8)基板加熱:室温。
2)Tiターゲット(5N):直径2インチ、厚さ5mm
3)Znターゲット(4N):直径2インチ、厚さ5mm。
2)スパッタ膜厚:Siは常に100nmで添加元素(Ti、Zn)の分はスパッタパワーごとに適宜変化させた。詳しくは、添加元素(Ti、Zn)濃度の増加に伴い、添加元素濃度の分が厚くなるようにスパッタパワーごとにDC電源をそれぞれ変化させて行った。
2)膜厚測定(スパッタレート算出のため):膜厚計(東京インスツルメンツ)
3)膜状態分析:ラマン分光測定(ブルカー社)。
(2)評価用セル(CR2032型コインセル)の作製
上記(1)で得られた評価用電極を使用し、下記コインセル仕様にて評価用セルを作成した。
なお、対極には、正極スラリー電極(例えば、LiCoO2、LiNiO2、LiMn2O4、Li(Ni、Mn、Co)O2、Li(Li、Ni、Mn、Co)O2、LiRO2-LiMn2O4(R=Ni、Mn、Co等の遷移金属元素)でも可能である。
3)セパレータ:セルガード2400(セルガード社製)
4)電解液:1M LiPF6/EC+DEC(1:1(体積比))
5)評価用電極:上記(1)で作製した合金サンプル1~25(表1参照)。
2.充放電試験条件・評価方法
(1)充放電試験条件
(i)評価用セルの充放電試験条件は以下の通りとした。
2)充放電条件[充電過程]0.1mA、2V→10mV(定電流・定電圧モード)
[放電過程]0.1mA、10mV→2V(定電流モード)
3)恒温槽:PFU-3K(エスペック株式会社製)
4)評価温度:300K(27℃)。
(2)評価方法
充放電容量は、合金重量当りで算出した。
(2)表中の50サイクル目の「放電容量維持率(%)」は、「初期容量からどれだけ容量を維持しているか」の指標を表す。放電容量維持率(%)の計算式は下記の通りである。
なお初期サイクル~10サイクル、通常は5~10サイクルの間で最大放電容量を示す。
サンプル4、19、22の評価用電極を用いた評価用セル(CR2032型コインセル)につき、実施例1と同様の充放電条件で初期サイクルを実施した。初期サイクルの放電過程での電圧(V)に対するdQ/dV曲線を図10に示す。
11 正極集電体、
12 負極集電体、
13 正極活物質層、
15 負極活物質層、
17 電解質層、
19 単電池層、
21、57 発電要素、
25、58 正極集電板、
27、59 負極集電板、
29、52 電池外装材(ラミネートフィルム)。
Claims (8)
- 組成式SixTiyZnz(式中x、y、及びzは質量パーセント値を表し、(1)x+y+z=100であり、(2)38≦x<100であり、(3)0<y<62であり、(4)0<z<62である。)を有する合金を含む電気デバイス用の負極活物質。
- (1)x+y+z=100であり、(2)38≦x<100であり、(3)0<y≦42であり、(4)0<z≦39であることを特徴とする請求項1に記載の電気デバイス用の負極活物質。
- (1)x+y+z=100であり、(2)38≦x≦72であり、(3)8≦y≦42であり、(4)12≦z≦39であることを特徴とする請求項1または2に記載の電気デバイス用の負極活物質。
- (1)x+y+z=100であり、(2)38≦x≦61であり、(3)19≦y≦42であり、(4)12≦z≦35であることを特徴とする請求項1~3のいずれかに記載の電気デバイス用の負極活物質。
- (1)x+y+z=100であり、(2)47≦x≦53であり、(3)19≦y≦21であり、(4)26≦z≦35であることを特徴とする請求項1~4のいずれかに記載の電気デバイス用の負極活物質。
- 請求項1~5のいずれかに記載の負極活物質を用いてなることを特徴とする電気デバイス用の負極。
- 請求項1~5のいずれかに記載の負極活物質、または請求項6に記載の負極を用いてなることを特徴とする電気デバイス。
- リチウムイオン二次電池である、請求項7に記載の電気デバイス。
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RU2012107439/02A RU2509819C2 (ru) | 2009-11-27 | 2010-11-26 | Активный материал отрицательного электрода на основе кремниевого сплава для электрического устройства |
EP10833348.5A EP2506347B1 (en) | 2009-11-27 | 2010-11-26 | Si alloy negative electrode active material for electrical device |
JP2011543333A JP5333605B2 (ja) | 2009-11-27 | 2010-11-26 | 電気デバイス用Si合金負極活物質 |
CN201080041178.0A CN102598369B (zh) | 2009-11-27 | 2010-11-26 | 电气器件用Si合金负极活性材料 |
KR1020127005904A KR101389156B1 (ko) | 2009-11-27 | 2010-11-26 | 전기 디바이스용 Si 합금 부극 활물질 |
BR112012005416A BR112012005416A2 (pt) | 2009-11-27 | 2010-11-26 | material ativo de liga de eletrodo negativo para dispositivo elétrico |
US13/393,048 US8835052B2 (en) | 2009-11-27 | 2010-11-26 | Si alloy negative electrode active material for electric device |
MX2012002805A MX2012002805A (es) | 2009-11-27 | 2010-11-26 | Material activo del electrodo negativo, de aleacion de si, para dispositivos electricos. |
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US20130056349A1 (en) * | 2011-09-01 | 2013-03-07 | Eiji Kitagawa | Sputtering target and method of manufacturing magnetic memory using the same |
WO2014080891A1 (ja) * | 2012-11-22 | 2014-05-30 | 日産自動車株式会社 | 電気デバイス用負極、及びこれを用いた電気デバイス |
WO2014080890A1 (ja) * | 2012-11-22 | 2014-05-30 | 日産自動車株式会社 | 電気デバイス用負極、及びこれを用いた電気デバイス |
WO2014080893A1 (ja) * | 2012-11-22 | 2014-05-30 | 日産自動車株式会社 | 電気デバイス用負極、及びこれを用いた電気デバイス |
WO2014080888A1 (ja) * | 2012-11-22 | 2014-05-30 | 日産自動車株式会社 | 電気デバイス用負極、及びこれを用いた電気デバイス |
WO2015060443A1 (ja) * | 2013-10-25 | 2015-04-30 | 日立マクセル株式会社 | 非水電解質二次電池用負極活物質、非水電解質二次電池用負極、及び非水電解質二次電池 |
WO2017013718A1 (ja) * | 2015-07-17 | 2017-01-26 | 株式会社 東芝 | 非水電解質電池および電池パック |
US10290855B2 (en) | 2012-11-22 | 2019-05-14 | Nissan Motor Co., Ltd. | Negative electrode for electrical device, and electrical device using the same |
US10367198B2 (en) | 2011-05-25 | 2019-07-30 | Nissan Motor Co., Ltd. | Negative electrode active material for electric device |
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JP6024760B2 (ja) * | 2012-11-22 | 2016-11-16 | 日産自動車株式会社 | リチウムイオン二次電池用負極、及びこれを用いたリチウムイオン二次電池 |
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Also Published As
Publication number | Publication date |
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BR112012005416A2 (pt) | 2016-04-12 |
CN102598369B (zh) | 2015-04-15 |
MX2012002805A (es) | 2012-04-02 |
RU2012107439A (ru) | 2014-01-10 |
JP5333605B2 (ja) | 2013-11-06 |
CN102598369A (zh) | 2012-07-18 |
EP2506347A1 (en) | 2012-10-03 |
EP2506347A4 (en) | 2014-08-06 |
US20120153220A1 (en) | 2012-06-21 |
JPWO2011065503A1 (ja) | 2013-04-18 |
RU2509819C2 (ru) | 2014-03-20 |
US8835052B2 (en) | 2014-09-16 |
EP2506347B1 (en) | 2018-04-25 |
KR101389156B1 (ko) | 2014-04-24 |
KR20120054619A (ko) | 2012-05-30 |
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