WO2011135931A1 - リチウムイオン二次電池 - Google Patents
リチウムイオン二次電池 Download PDFInfo
- Publication number
- WO2011135931A1 WO2011135931A1 PCT/JP2011/055460 JP2011055460W WO2011135931A1 WO 2011135931 A1 WO2011135931 A1 WO 2011135931A1 JP 2011055460 W JP2011055460 W JP 2011055460W WO 2011135931 A1 WO2011135931 A1 WO 2011135931A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- positive electrode
- active material
- negative electrode
- electrode active
- secondary battery
- Prior art date
Links
Classifications
-
- 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
-
- 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
-
- 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
- H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
- H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
- H01M10/0566—Liquid materials
- H01M10/0568—Liquid materials characterised by the solutes
-
- 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
-
- 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
-
- 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
- H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
- H01M4/50—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese
- H01M4/505—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy
-
- 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
- H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
- H01M4/52—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron
- H01M4/525—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
-
- 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
-
- 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
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T10/00—Road transport of goods or passengers
- Y02T10/60—Other road transportation technologies with climate change mitigation effect
- Y02T10/70—Energy storage systems for electromobility, e.g. batteries
Definitions
- the present invention relates to a lithium ion secondary battery used as a power source for driving a motor of, for example, an electric vehicle or a hybrid electric vehicle. More specifically, the capacity characteristic and cycle characteristic of the secondary battery can be improved.
- the present invention relates to a combination of an electrode active material and a supporting electrolyte.
- a positive electrode in which a positive electrode active material or the like is applied to both surfaces of a positive electrode current collector 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 are connected via an electrolyte layer. And has a structure housed in a battery case.
- the composite oxide used as the positive electrode active material can be represented by, for example, a general formula of aLi [Li 1/3 M1 2/3 ] O 2.
- (1-a) LiM 2 O 2 and has a high discharge capacity of 200 mAh / g.
- it has excellent cycle characteristics and thermal stability, and is expected to have excellent performance as a positive electrode active material.
- it is desirable to use not only the positive electrode but also the negative electrode active material having a high capacity.
- a negative electrode active material capable of realizing a high capacity a silicon (Si) negative electrode active material having a much higher capacity than a carbon material or the like is attracting attention.
- the present invention has been made in order to solve the above problems in a lithium ion secondary battery when a composite oxide containing lithium as described above is used as a positive electrode active material and a negative electrode active material composed of a silicon-based material is combined. It is. And the purpose is that not only high capacity but also high cycle characteristics (high capacity retention rate) are obtained when the above-mentioned high capacity positive electrode active material and negative electrode active material are combined. It is in providing the lithium ion secondary battery which can also be implement
- the present inventors have found that the above object can be achieved by applying a lithium salt having a predetermined component structure as a supporting salt used in a non-aqueous electrolyte.
- the present invention has been completed.
- the present invention is based on the above knowledge, and the lithium ion secondary battery of the present invention is a lithium ion secondary battery comprising a positive electrode and a negative electrode capable of occluding and releasing lithium, and a non-aqueous electrolyte composition.
- the negative electrode contains a negative electrode active material containing silicon
- the positive electrode has a composition formula (1), that is, aLi [Li 1/3 M1 2/3 ] O 2.
- the non-aqueous electrolyte composition has a chemical formula (2), that is, (C n F 2n + 1 SO 2 ) (C m F 2m + 1 SO 2) NLi ( m in wherein, n an integer of 2 or more, each Characterized in that it contains a lithium salt represented by you).
- a lithium ion secondary material using a lithium-containing composite oxide represented by a predetermined composition formula as a high-capacity positive electrode active material and using a silicon-containing material as a high-capacity positive electrode active material since the lithium salt of the predetermined component is used as the supporting electrolyte, a secondary battery having high capacity and high cycle characteristics can be obtained.
- the present invention is a lithium ion secondary battery including a positive electrode and a negative electrode capable of inserting and extracting lithium, and a non-aqueous electrolyte composition, wherein the negative electrode contains a negative electrode active material containing silicon.
- the positive electrode contains a positive electrode active material represented by the composition formula of aLi [Li 1/3 M1 2/3 ] O 2. (1-a) LiM2O 2 , and the non-aqueous electrolyte composition is (C n F 2n + 1 SO 2 ) (C m F 2m + 1 SO 2 ) N Li lithium salt represented by the chemical formula is included.
- a composite oxide positive electrode and a silicon negative electrode that can be charged / discharged at a high potential and exhibit a high capacity are combined, and a non-aqueous electrolyte composition (a generic term that includes gel electrolytes and solid polymer electrolytes together with electrolytes).
- a lithium salt represented by the above chemical formula is used as the supporting electrolyte to be constructed.
- Nonaqueous electrolyte composition In general, a liquid nonaqueous electrolyte, that is, an electrolytic solution is used for the lithium ion secondary battery. In the lithium ion secondary battery of the present invention, not only such a nonaqueous electrolytic solution but also a polymer electrolyte (intrinsic polymer) is used. It is also possible to use an electrolyte or a gel polymer electrolyte. In the present invention, the “non-aqueous electrolyte composition” means a concept generically referring to such non-aqueous electrolytes regardless of the form such as liquid, gel or solid.
- LiPF 6 Lithium hexafluorophosphate
- LiPF 6 LiPF 6
- LiPF 6 ⁇ ⁇ LiF + PF 5 LiPF 6 + H 2 O ⁇ ⁇ 2HF + PF 3 O (5)
- the above formula (3) shows the ion dissociation of LiPF 6 in the electrolyte and is a reaction that occurs regardless of the presence or absence of H 2 O.
- Formula (4) shows the LiPF 6 equilibrium state, which is a complex salt
- Formula (5) is a reaction formula showing the decomposition of PF 5 and the production of HF that occur in the presence of H 2 O.
- normally about 20 ppm of water is inevitably mixed in the electrolytic solution, and it is virtually impossible to completely suppress the reaction.
- the SiO 2 is the formula It reacts with HF produced by (5) as shown in the following formula (6). SiO 2 + 4HF ⁇ SiF 4 + 2H 2 O (6)
- the lithium salt which is the supporting electrolyte in the present invention is represented by the chemical formula of (C n F 2n + 1 SO 2 ) (C m F 2m + 1 SO 2 ) NLi, and the fluorine (F) atom is carbon.
- C Since atoms are bonded by a covalent bond, the chemical stability is excellent, and even when H 2 O is present, generation of HF can be prevented as compared with LiPF 6 described above.
- the values of m and n in the above chemical formula must be integers of 2 or more.
- Specific examples of such lithium salts include (CF 3 CF 2 SO 2 ) 2 NLi (hereinafter, “ LiBETI ”(sometimes abbreviated as lithium bis (pentafluoroethanesulfonyl) imide).
- the values of m and n in the lithium salt are integers of 2 or more, there is no problem even if the values are different from each other, but if it exceeds 5 (6 or more), the molecular weight as the lithium salt increases. The ionic conductivity tends to decrease, and therefore it is preferable that each is 5 or less.
- lithium salt used as a supporting electrolyte used in a lithium ion secondary battery inorganic lithium salts containing no fluorine such as lithium perchlorate (LiClO 4 ) and lithium tetrachloride aluminum oxide (LiAlCl 4 ) are also known.
- lithium perchlorate LiClO 4
- lithium tetrachloride aluminum oxide LiAlCl 4
- the electrolytic solution used in the lithium ion secondary battery of the present invention contains a lithium salt (supporting electrolyte) represented by the above chemical formula (2) in a non-aqueous solvent.
- a dielectric constant solvent or a low-viscosity solvent can be used, and these can be used alone or in combination.
- the high dielectric constant solvent include ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), and vinylene carbonate (VC).
- VC vinylene carbonate
- dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), methyl propyl carbonate (MPC), or the like can be used.
- the said electrolyte solution can also be used in the state made to impregnate the separator which consists of a porous sheet and a nonwoven fabric.
- the separator has a function to prevent internal short circuit by interposing between the positive electrode and the negative electrode.
- the separator when an excessive current flows through the battery, the separator can be provided with a shutdown function that closes the pores of the porous sheet by the heat generation and cuts off the current.
- a laminated structure composed of three-layer porous sheets of PE / PP / PE of different sizes is preferably used.
- the polymer electrolyte is not particularly limited as long as it is composed of an ion conductive polymer and has ion conductivity.
- a polymerized ion conductive polymer that is crosslinked by thermal polymerization, ultraviolet polymerization, radiation polymerization, electron beam polymerization or the like is preferably used.
- the polymer electrolyte include an intrinsic polymer electrolyte and a gel polymer electrolyte.
- Examples of intrinsic polymer electrolytes include polyethylene oxide (PEO), polypropylene oxide (PPO), and copolymers thereof.
- PEO polyethylene oxide
- PPO polypropylene oxide
- copolymers thereof examples include polyethylene oxide (PEO), polypropylene oxide (PPO), and copolymers thereof.
- PEO polyethylene oxide
- PPO polypropylene oxide
- copolymers thereof examples include polyethylene oxide (PEO), polypropylene oxide (PPO), and copolymers thereof.
- PEO polyethylene oxide
- PPO polypropylene oxide
- copolymers thereof examples include polyethylene oxide (PEO), polypropylene oxide (PPO), and copolymers thereof.
- the above lithium salt (supporting electrolyte) is well dissolved.
- these polymers exhibit excellent mechanical strength by forming a crosslinked structure.
- the gel polymer electrolyte generally means an all-solid polymer electrolyte having ionic conductivity in which the above-described electrolytic solution is held.
- a gel polymer electrolyte in which a similar electrolytic solution is held in a polymer skeleton having no lithium ion conductivity such as polyvinylidene fluoride (PVdF) and polyacrylonitrile, is also used. Shall be included.
- the gel polymer electrolyte can be obtained by polymerization by the above-described method.
- the filling amount of the electrolytic solution can be increased and the thermal conductivity inside the battery can be improved.
- the content of the lithium salt in each electrolyte composition is preferably about 0.5 to 1.5 mol / L, more preferably about 0.8 to 1.2 mol / L. If the lithium salt content is less than 0.5 mol / L or more than 1.5 mol / L, sufficient ionic conductivity may not be obtained.
- the supporting electrolyte contained in the electrolyte composition used in the present invention only the lithium salt represented by the chemical formula (2) (including a mixture of materials having different values of n and m) is used. However, it can be used in combination with a supporting electrolyte that does not generate HF.
- the positive electrode has a structure in which a positive electrode active material layer is formed on one side or both sides of a current collector (positive electrode current collector) made of a conductive material such as an aluminum foil, a copper foil, a nickel foil, or a stainless steel foil.
- the thickness of the current collector is not particularly limited, but is generally preferably about 1 to 30 ⁇ m.
- a positive electrode active material layer contains a conductive support agent and a binder with a positive electrode active material as needed.
- a lithium-containing composite oxide represented by the composition formula (1) of aLi [Li 1/3 M1 2/3 ] O 2.
- (1-a) LiM2O 2 is used as the positive electrode active material.
- M1 is one or more metal elements selected from the group consisting of Mn, Ti, Zr and V
- M2 is composed of Ni, Co, Mn, Al, Cr, Fe, V, Mg and Zn. It is one or more metal elements selected from the group, and a is more than 0 and less than 1 and is preferably 0.5 to 0.9.
- a composite oxide synthesized by a solid phase method or a solution method can be used.
- the particle size of the composite oxide is not particularly limited and is generally desirable to be finer. However, in consideration of work efficiency and ease of handling, the average particle size may be about 1 to 30 ⁇ m. More preferably, it is about 10 to 20 ⁇ m.
- the conductive auxiliary agent contained in the positive electrode active material layer is blended to improve the battery performance by increasing the conductivity of the active material layer.
- acetylene black, carbon black, graphite, carbon fiber, etc. Can be used.
- binder for example, polyvinylidene fluoride (PVdF), polyimide, a synthetic rubber binder, or the like can be used.
- PVdF polyvinylidene fluoride
- polyimide polyimide
- synthetic rubber binder or the like
- the negative electrode has a structure in which a negative electrode active material layer is formed on one side or both sides of a current collector (negative electrode current collector) made of a conductive material as described above, similarly to the positive electrode.
- the negative electrode active material layer can contain the same conductive additive and binder as those of the above-described positive electrode active material, if necessary, together with the negative electrode active material.
- the negative electrode active material in the present invention a material containing silicon (Si) as a main component, for example, pure silicon, an alloy containing 90% or more of silicon, semiconductor silicon containing an extremely small amount of dopant such as boron or phosphorus, or the like is used. It is preferable.
- the negative electrode active material containing silicon as a main component has a higher ability to occlude and release lithium and has a much higher capacity than other negative electrode active materials such as carbon materials.
- the positive electrode active material layer and the negative electrode active material layer are formed on one surface or both surfaces of each current collector, but the positive electrode active material layer on one surface of one current collector, A negative electrode active material layer can be formed on each of the other surfaces, and such an electrode can be applied to a bipolar battery.
- Negative electrode paste 1 Silicon powder as the negative electrode active material (average particle diameter of primary particles: 1 ⁇ m), acetylene black as the conductive auxiliary agent, and polyimide as the binder are blended in a mass ratio of 40:40:20. -Methylpyrrolidone was added as a solvent and mixed to obtain negative electrode paste 1.
- Negative electrode paste 2 A negative electrode paste 2 was obtained by repeating the same operation as that of the negative electrode paste 1 except that an alloy powder having a mass composition ratio of Si90Zn10 was used instead of the silicon powder.
- Negative electrode paste 3 The negative electrode paste 3 was obtained by repeating the same operation as that of the negative electrode paste 1 except that an alloy powder having a mass composition ratio of Si90Ti10 was used instead of the silicon powder.
- discharge capacity retention ratio is the percentage of the discharge capacity at the 50th cycle relative to the discharge capacity at the first cycle, expressed as a percentage.
- Positive electrode active material A metal sulfates, ie, NiSO 4 .6H 2 O, CoSO 4 .7H 2 O, MnSO 4 .5H 2 O, were used, and the molar ratio of Ni: Co: Mn was 0.21: 0.085. : Weighed to 0.56 and mixed with high purity water to adjust to 2.0 mol / L. On the other hand, the precipitating agent NaCO 3 was similarly adjusted to 2.0 mol / L, and the complexing agent 25% NH 4 OH aqueous solution was diluted to 0.2 mol / L.
- the aqueous metal sulfate solution was stirred with a magnetic stirrer for 30 minutes and ultrasonically for 10 minutes, and while maintaining the pH at 7.0 to 7.5, NaCO 3 was slowly dropped into the aqueous solution and NH 4 OH solution.
- the metal complex carbonate was precipitated.
- the obtained nickel-cobalt-manganese composite carbonate was suction filtered, washed thoroughly with high-purity water to remove Na, and then dried with a 120 ° C. dryer for 5 hours. Pre-baking after drying was performed in the atmosphere at 500 ° C. for 5 hours to obtain a nickel cobalt manganese oxide precursor.
- LiOH.H 2 O was weighed into the obtained precursor so that the molar ratio of Li was 1.16, and pulverized and mixed for 30 minutes with an automatic mortar.
- the obtained mixture was formed into pellets at a pressure of 1.5 ton / cm 2 , subjected to main calcination in the atmosphere at 900 ° C. for 12 hours, and then quenched into liquid nitrogen.
- the target composite oxide 0.5 Li [ Li 1/3 Mn 2/3 ] O 2 .0.5 (Li [Ni 0.42 Co 0.17 Mn 0.42 ] O 2 ) was obtained, and the positive electrode active material A was obtained by adjusting the average particle size to 5 ⁇ m.
- Positive electrode active material B By changing the molar ratio of Ni: Co: Mn and the molar ratio with respect to the nickel cobalt manganese oxide precursor, the same operation as described above was repeated to obtain the target composite oxide 0.6 (Li [Li 1/3 Mn 2/3 ] O 2 .0.4 (Li [Ni 0.47 Co 0.08 Mn 0.47 ] O 2 ) was obtained, and the positive electrode active material B was prepared by adjusting to the same average particle diameter.
- Positive electrode paste 1 The positive electrode active material A obtained as described above, acetylene black as a conductive additive, and polyvinylidene fluoride (PVdF) as a binder were blended in a mass ratio of 70:20:10, and N-methyl was added thereto. Pyrrolidone was added as a solvent and mixed to obtain a positive electrode paste 1.
- PVdF polyvinylidene fluoride
- Positive electrode paste 2 The positive electrode paste 2 was obtained by repeating the same operation as the positive electrode paste 1 except that the positive electrode active material B was used in place of the positive electrode active material A.
- Positive electrode paste 3 The positive electrode paste 3 was obtained by repeating the same operation as the positive electrode paste 1 except that the positive electrode active material C was used in place of the positive electrode active material A.
- discharge capacity retention ratio is a percentage of the discharge capacity at the 10th cycle to the discharge capacity at the 1st cycle.
- - in the table means that charging / discharging is impossible.
- LiPF 6 or LiBETI can be applied to the positive electrode containing the composite oxide represented by the composition formula (1) as an active material among the supporting electrolytes composed of three lithium salts. It has been found. Further, it was found that for the type of composite oxide positive electrode (composition), differences in performance between LiPF 6 and LiBETI is not substantially observed.
- discharge capacity retention ratio refers to the ratio of the discharge capacity at the 10th cycle to the discharge capacity at the first cycle (initial capacity) based on the weight of the positive electrode active material, and is expressed as a percentage. . “-” Means that charging / discharging is not possible, as in Table 2.
- composition ratio a 0.6
Landscapes
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Inorganic Chemistry (AREA)
- Manufacturing & Machinery (AREA)
- Materials Engineering (AREA)
- Physics & Mathematics (AREA)
- Condensed Matter Physics & Semiconductors (AREA)
- General Physics & Mathematics (AREA)
- Battery Electrode And Active Subsutance (AREA)
- Secondary Cells (AREA)
Abstract
Description
このようなモータ駆動用の二次電池としては、特に高容量であることやサイクル特性に優れていることが求められることから、各種二次電池の中でも高い理論エネルギを有するリチウムイオン二次電池が着目されている。
そこで、リチウムイオン二次電池の正極活物質として、xLi[Mn1/2Ni1/2]O2・yLiCoO2・zLi[Li1/3Mn2/3]O2(x+y+z=1、0<x<1、0≦y<0.5、0<z<1)を用い、負極活物質としては、カーボン材料を用いることが提案されている(特許文献1を参照)。
一方、電池全体として高い容量特性を実現するためには、正極のみならず、負極活物質についても高容量のものを用いることが望ましい。そこで、高容量を実現できる負極活物質として、カーボン材料などと比べてはるかに容量の高いシリコン(Si)系の負極活物質が注目される。
また、支持電解質として最も一般的な六フッ化リン酸リチウム(LiPF6)を含む電解液の場合、LiPF6の加水分解によってフッ化水素(HF)が発生し、これが負極のシリコンと反応することから、負極性能の低下が生じることがある。
すなわち、高電位で充放電することができ、高容量を示す複合酸化物正極とシリコン負極を組み合わせ、非水電解質組成物(電解液と共に、ゲル状、固体状のポリマー電解質をも含む総称)を構成する支持電解質として、上記化学式で示されるリチウム塩を用いたものである。
リチウムイオン二次電池には、一般に液状の非水電解質、すなわち電解液が用いられるが、本発明のリチウムイオン二次電池においては、このような非水電解液のみならず、ポリマー電解質(真性ポリマー電解質、ゲルポリマー電解質)を使用することも可能である。
本発明において「非水電解質組成物」とは、これら液状、ゲル状、固体状など、形態を問わず、このような非水電解質を総称する概念を意味する。
Li+ + PF6 - ←→ LiPF6 ・・・ (3)
LiPF6 ←→ LiF + PF5 ・・・ (4)
PF5 + H2O ←→ 2HF + PF3O ・・・ (5)
SiO2 + 4HF → SiF4 + 2H2O ・・・ (6)
SiF4 + 2H2O → SiO2 + 4HF ・・・ (7)
SiF4 + 2HF → H2SiF6 ・・・ (8)
このような連続反応によって、負極中の活物質であるシリコンが減少するため、このような負極活物質(Si)と支持電解質(LiPF6)を用いた二次電池においては、電気容量が低下する結果となる。
ここで、上記化学式におけるm及びnの値は、それぞれ2以上の整数でなければならず、このようなリチウム塩の具体例としては、例えば(CF3CF2SO2)2NLi(以下、「LiBETI」(リチウムビス(ペンタフルオロエタンスルホニル)イミド)と略称することがある。)を挙げることができる。
一方、上記化学式におけるm及びnの値が2に満たない場合(m=n=1)、つまり上記リチウム塩が(CF3SO2)2NLiである場合には、正極の充電電位である4.8Vに耐えることができず、分解してしまうことから、支持電解質として使用することができない。
ここで、高誘電率溶媒としては、エチレンカーボネート(EC)、プロピレンカーボネート(PC)、ブチレンカーボネート(BC)、ビニレンカーボネート(VC)等を挙げることができる。また、低粘度溶媒としては、ジメチルカーボネート(DMC)、ジエチルカーボネート(DEC)、エチルメチルカーボネート(EMC)、メチルプロピルカーボネート(MPC)などを使用することができる。
セパレータは、正極と負極との間に介在して内部短絡を防止する機能を有し、綿、レーヨン、アセテート、ポリアミド、ポリエステル、ポリエチレン(PE)、ポリプロピレン(PP)、ポリイミド、アラミドなどの天然・合成繊維又はセラミックス繊維から成る不織布や、ポリエチレン、ポリプロピレン、ポリイミド、アラミドなどのポリマーから成る多孔性シートなど、イオン透過度が大きく、所定の機械的強度を有する絶縁性の材料が用いられる。なお、2種以上の多孔質シートの積層構造を採用することも可能である。
ポリマー電解質としては、真性ポリマー電解質、ゲルポリマー電解質を挙げることができる。
なお、本発明においては、例えば、ポリフッ化ビニリデン(PVdF)やポリアクリロニトリルのように、リチウムイオン伝導性を有しない高分子の骨格中に、同様の電解液を保持させたものも、ゲルポリマー電解質に含まれるものとする。
なお、本発明に用いる電解質組成物中に含まれる支持電解質としては、上記化学式(2)で表されるリチウム塩のみ(n、mの値が異なるもの同士の混合物を含む)を用いることを基本とするが、HFを発生することのない支持電解質との併用は差し支えない。
正極は、アルミニウム箔、銅箔、ニッケル箔、ステンレス箔などの導電性の材料から成る集電体(正極集電体)の片面又は両面に、正極活物質層を形成した構造を備えている。なお、集電体の厚さは、特に限定されないが、一般には1~30μm程度とすることが好ましい。
正極活物質層は、正極活物質と共に、必要に応じて導電助剤やバインダを含む。
このとき、上記組成比aが上記範囲外、すなわちa=0の場合には、Li量が少なくなって、容量が不足し、a=1の場合には、充放電ができなくなって、正極活物質として使えないもの(すなわち、理論容量が0mAh/g)となる。
当該複合酸化物の粒径としては、特に限定するものではなく、一般には細かいほど望ましいが、作業能率や取り扱いの容易さなどを考慮すると、平均粒径で、1~30μm程度であればよく、10~20μm程度であることがより好ましい。
また、バインダ(結着剤)としては、例えば、ポリフッ化ビニリデン(PVdF)やポリイミド、合成ゴム系バインダ等を用いることができる。
なお、正極活物質層中におけるこれら正極活物質、導電助剤、バインダの配合比としては、特に限定されない。
一方、負極は、正極と同様に、上記したような導電性の材料から成る集電体(負極集電体)の片面又は両面に、負極極活物質層を形成した構造を備えている。
負極活物質層についても、正極の場合と同様に、負極活物質と共に、必要に応じて、上記した正極活物質の場合と同様の導電助剤やバインダを含有させることができる。
主な成分としてシリコンを含有する上記負極活物質は、カーボン材料等、他の負極活物質と比べて、リチウムを吸蔵及び放出する能力が高く、はるかに高い容量を示す。
〔1〕負極ペーストの作製
〔1-1〕負極ペースト1
負極活物質としてのシリコン粉末(1次粒子の平均粒子径:1μm)、導電助剤としてのアセチレンブラック、バインダとしてのポリイミドを40:40:20の質量比となるように配合し、これにN-メチルピロリドンを溶媒として添加して、混合し、負極ペースト1を得た。
上記シリコン粉末に替えて、Si90Zn10の質量組成比から成る合金粉末を使用したこと以外は、上記負極ペースト1と同様の操作を繰り返すことによって、負極ペースト2を得た。
上記シリコン粉末に替えて、Si90Ti10の質量組成比から成る合金粉末を使用したこと以外は、上記負極ペースト1と同様の操作を繰り返し、これにより負極ペースト3を得た。
集電体として銅箔を使用し、該銅箔の両面に、上記で得た負極ペースト1~3をそれぞれ70μmの厚さとなるように塗布し、十分に乾燥させることによって負極を作製した。得られた負極は、それぞれ80℃で真空乾燥したのち、300℃-30分間の熱処理を施した。
非水溶媒として、エチレンカーボネートとジエチレンカーボネートを50:50の容積比で混合し、この混合溶媒中に、LiPF6(六フッ化リン酸リチウム)、(CF3SO2)2NLi(略称:LiTFSI)及び(CF3CF2SO2)2NLi(略称:LiBETI)をそれぞれ1Mの濃度となるように溶解させ、3種の電解液を得た。
上記で作製したそれぞれの負極と、ステンレスディスクに金属リチウムを貼り付けた正極とを対向させ、この間に、ポリオレフィン製、厚さ20μmのセパレータを配置した。
この負極・セパレータ・正極の積層体をステンレス鋼(SUS316)製の電池缶内に配し、上記により調製した3種の電解液をそれぞれの電池缶内に注入したのち、密閉し、都合9種類のリチウムイオン二次電池(ハーフセル)を得た。
上記によって作製した各リチウムイオン二次電池について、50サイクルの充放電試験を行い、放電容量保持率を調べた。
すなわち、30℃の雰囲気下、定電流方式(CC、電流:0.1C)で2.0Vまで充電し、10分間休止させた後、定電流(CC、電流:0.1C)で0.01Vまで放電し、放電後10分間休止させる充放電過程を1サイクルとし、これを50回繰り返した。
〔1〕正極活物質の合成
まず、溶液法の一種である複合炭酸塩法によって、3種の正極活物質を合成した。この複合炭酸塩法は、収率が高く、しかも水溶液系であるため均一組成を得ることができ、水酸化物の共沈法よりも組成コントロールが容易であるという特徴を有している。
出発材料として、金属の硫酸化物、すなわちNiSO4・6H2O、CoSO4・7H2O、MnSO4・5H2Oを使用し、Ni:Co:Mnのモル比が0.21:0.085:0.56となるように秤量し、高純度水に混合して2.0mol/Lとなるように調整した。
一方、沈殿剤であるNaCO3も同様に2.0mol/Lとなるように調整し、錯化剤である25%NH4OH水溶液は、0.2mol/Lに希釈して使用した。
乾燥後の仮焼成を大気中500℃で、5時間行い、ニッケルコバルトマンガン酸化物の前駆体を得た。
Ni:Co:Mnのモル比、ニッケルコバルトマンガン酸化物前駆体に対するモル比を変更した上で、上記同様の操作を繰り返すことにより、目的の複合酸化物0.6(Li[Li1/3Mn2/3]O2・0.4(Li[Ni0.47Co0.08Mn0.47]O2)を得た。そして、同様の平均粒径に調整して正極活物質Bとした。
Ni:Co:Mnのモル比、ニッケルコバルトマンガン酸化物前駆体に対するモル比を変更した上で、上記同様の操作を繰り返すことにより、目的の複合酸化物0.9(Li[Li1/3Mn2/3]O2・0.1(Li[Ni0.42Co0.17Mn0.42]O2)を得、平均粒径を同様に調整して正極活物質Cとした。
〔2-1〕正極ペースト1
上記により得られた正極活物質Aと、導電助剤としてのアセチレンブラックと、バインダとしてのポリフッ化ビニリデン(PVdF)を70:20:10の質量比となるように配合し、これにN-メチルピロリドンを溶媒として添加して、混合し、正極ペースト1を得た。
上記正極活物質Aに替えて、正極活物質Bを用いたこと以外は、上記正極ペースト1と同様の操作を繰り返すことによって、正極ペースト2を得た。
上記正極活物質Aに替えて、正極活物質Cを用いたこと以外は、上記正極ペースト1と同様の操作を繰り返すことによって、正極ペースト3を得た。
集電体としてアルミニウム箔を使用し、この両面に、上記で得た正極ペースト1~3をそれぞれ70μmの厚さとなるように塗布し、十分に乾燥させることによって正極を作製した。得られた正極は、それぞれ80℃で真空乾燥した。
上記で作製したそれぞれの正極と、ステンレスディスクに金属リチウムを貼り付けた負極とを対向させ、この間に、ポリオレフィン製、厚さ20μmのセパレータを配置した。
この負極・セパレータ・正極の積層体をステンレス鋼(SUS316)製の電池缶内に配し、負極ハーフセルの場合と同様に調製した3種の電解液をそれぞれの電池缶内に注入したのち、密閉し、都合9種類のリチウムイオン二次電池(ハーフセル)を得た。
上記によって作製した各リチウムイオン二次電池について、10サイクルの充放電試験を行い、放電容量保持率について調査した。
すなわち、30℃の雰囲気下、定電流方式(CC、電流:0.1C)で4.8Vまで充電し、10分間休止させた後、定電流(CC、電流:0.1C)で2Vまで放電し、放電後10分間休止させる充放電過程を1サイクルとし、これを10回繰り返した。
〔1〕フルセルの作製
正極活物質A~Cを含む上記正極ペースト1~3を塗布して成るそれぞれの正極と、シリコン又はシリコン含有合金を負極活物質として含む上記負極ペースト1~3を塗布して成るそれぞれの負極とを組み合わせて対向させ、この間に、上記したセパレータを配置した。
そして、この負極・セパレータ・正極の積層体をステンレス鋼製の上記電池缶内に配し、上記同様に調製した3種の電解液をそれぞれの電池缶内に注入したのち、密閉し、都合13種類のリチウムイオン二次電池(比較例8種、実施例5種)を得た。
上記によって作製した各リチウムイオン二次電池について、正極ハーフセルの場合と同様に、10サイクルの充放電試験を行い、放電容量保持率について調査した。
すなわち、30℃の雰囲気下、定電流方式(CC、電流:0.1C)で4.8Vまで充電し、10分間休止させた後、定電流(CC、電流:0.1C)で2Vまで放電し、放電後10分間休止させる充放電過程を1サイクルとし、これを10回繰り返した。
また、活物質Bを含む正極と、Si-10%Zn活物質を含む負極とを組み合わせた比較例2、5、実施例2を比較した場合も、リチウム塩種について同様の傾向を示した。
さらに、活物質Aを含む正極と純シリコン活物質を含む負極とを組み合わせた比較例7と実施例1、活物質Cを含む正極と純シリコン活物質を含む負極との組み合わせに係る比較例8と実施例5をそれぞれ比較すると、LiPF6よりも(CF3CF2SO2)2NLiを用いた方が放電容量維持率に優れることが判った。
Claims (3)
- リチウムの吸蔵及び放出が可能な正極及び負極と、非水電解質組成物を備えたリチウムイオン二次電池において、
上記負極はシリコンを含む負極活物質を含有し、
上記正極は次の組成式(1)で表される正極活物質を含有し、
上記非水電解質組成物は次の化学式(2)で表されるリチウム塩を含むリチウムイオン二次電池。
aLi[Li1/3M12/3]O2・(1-a)LiM2O2 ・・・ (1)
(式中のM1はMn、Ti、Zr及びVから成る群から選ばれる1種以上の金属元素、M2はNi、Co、Mn、Al、Cr、Fe、V、Mg及びZnから成る群から選ばれる1種以上の金属元素を示し、0<a<1)
(CnF2n+1SO2)(CmF2m+1SO2)NLi ・・・ (2)
(式中のm,nはそれぞれ2以上の整数を示す) - 上記化学式(2)におけるm及びnが5以下である請求項1に記載のリチウムイオン二次電池。
- 上記組成式(1)における組成比aが0.5以上0.9以下である請求項1又は2に記載のリチウムイオン二次電池。
Priority Applications (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
KR1020127027907A KR101455918B1 (ko) | 2010-04-26 | 2011-03-09 | 리튬 이온 이차 전지 |
US13/643,207 US8968923B2 (en) | 2010-04-26 | 2011-03-09 | Lithium ion secondary battery |
CN201180021326.7A CN102859781B (zh) | 2010-04-26 | 2011-03-09 | 锂离子二次电池 |
EP11774715.4A EP2565974B1 (en) | 2010-04-26 | 2011-03-09 | Lithium ion secondary battery |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2010101103A JP5648828B2 (ja) | 2010-04-26 | 2010-04-26 | リチウムイオン二次電池 |
JP2010-101103 | 2010-04-26 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO2011135931A1 true WO2011135931A1 (ja) | 2011-11-03 |
Family
ID=44861252
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/JP2011/055460 WO2011135931A1 (ja) | 2010-04-26 | 2011-03-09 | リチウムイオン二次電池 |
Country Status (6)
Country | Link |
---|---|
US (1) | US8968923B2 (ja) |
EP (1) | EP2565974B1 (ja) |
JP (1) | JP5648828B2 (ja) |
KR (1) | KR101455918B1 (ja) |
CN (1) | CN102859781B (ja) |
WO (1) | WO2011135931A1 (ja) |
Families Citing this family (11)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP2458665A3 (de) * | 2010-11-25 | 2015-05-06 | Basf Se | Verfahren zur Herstellung von Vorstufen für Übergangsmetallmischoxide |
US9461309B2 (en) | 2012-08-21 | 2016-10-04 | Kratos LLC | Group IVA functionalized particles and methods of use thereof |
BR112015003794A2 (pt) | 2012-08-21 | 2017-07-04 | Kratos LLC | partículas funcionalizadas do grupo iva e métodos de uso destas |
JP2016027562A (ja) * | 2014-07-04 | 2016-02-18 | 株式会社半導体エネルギー研究所 | 二次電池の作製方法及び製造装置 |
EP3174154B1 (en) * | 2014-07-22 | 2019-05-01 | Rekrix Co., Ltd. | Silicone secondary battery unit and battery module for electrical vehicle using same |
US10790509B2 (en) * | 2016-01-06 | 2020-09-29 | Sumitomo Metal Mining Co., Ltd. | Positive-electrode active material precursor for nonaqueous electrolyte secondary battery, positive-electrode active material for nonaqueous electrolyte secondary battery, method for manufacturing positive-electrode active material precursor for nonaqueous electrolyte secondary battery, and method for manufacturing positive-electrode active material for nonaqueous electrolyte secondary battery |
CN112678877B (zh) * | 2016-01-06 | 2023-05-12 | 住友金属矿山株式会社 | 非水类电解质二次电池用正极活性物质 |
KR20190042558A (ko) | 2016-07-05 | 2019-04-24 | 크라토스 엘엘씨 | 부동태화된 예비리튬화된 마이크론 및 서브마이크론 iva족 입자 및 이의 제조방법 |
WO2018183909A1 (en) | 2017-03-31 | 2018-10-04 | Kratos LLC | Precharged negative electrode material for secondary battery |
WO2018198304A1 (ja) * | 2017-04-28 | 2018-11-01 | 日本新エネルギー技研株式会社 | 二次電池用の負極組成物、およびこれを用いた二次電池 |
WO2019107242A1 (ja) * | 2017-11-28 | 2019-06-06 | 日本電気株式会社 | リチウムイオン二次電池 |
Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2007287445A (ja) | 2006-04-14 | 2007-11-01 | Nissan Motor Co Ltd | 二次電池および組電池、並びにこれらを搭載する車両 |
JP2009158415A (ja) * | 2007-12-27 | 2009-07-16 | Mitsui Mining & Smelting Co Ltd | 非水電解液二次電池用正極活物質及びそれを有する非水電解液二次電池 |
Family Cites Families (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
KR20080076813A (ko) * | 2007-02-16 | 2008-08-20 | 소니 가부시끼가이샤 | 부극 및 그 제조 방법과 전지 |
-
2010
- 2010-04-26 JP JP2010101103A patent/JP5648828B2/ja not_active Expired - Fee Related
-
2011
- 2011-03-09 CN CN201180021326.7A patent/CN102859781B/zh not_active Expired - Fee Related
- 2011-03-09 WO PCT/JP2011/055460 patent/WO2011135931A1/ja active Application Filing
- 2011-03-09 KR KR1020127027907A patent/KR101455918B1/ko active IP Right Grant
- 2011-03-09 EP EP11774715.4A patent/EP2565974B1/en not_active Not-in-force
- 2011-03-09 US US13/643,207 patent/US8968923B2/en not_active Expired - Fee Related
Patent Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2007287445A (ja) | 2006-04-14 | 2007-11-01 | Nissan Motor Co Ltd | 二次電池および組電池、並びにこれらを搭載する車両 |
JP2009158415A (ja) * | 2007-12-27 | 2009-07-16 | Mitsui Mining & Smelting Co Ltd | 非水電解液二次電池用正極活物質及びそれを有する非水電解液二次電池 |
Non-Patent Citations (1)
Title |
---|
ATSUSHI ITO ET AL.: "Li Kajo So-jo Seikyoku Zairyo no Koyoryo Hatsugen Kiko no Kaimei", DAI 48 KAI BATTERY SYMPOSIUM IN JAPAN KOEN YOSHISHU, THE ELECTROCHEMICAL SOCIETY OF JAPAN DENCHI GIJUTSU IINKAI, 3 November 2007 (2007-11-03), pages 12 - 13, XP008169207 * |
Also Published As
Publication number | Publication date |
---|---|
KR20130023216A (ko) | 2013-03-07 |
US8968923B2 (en) | 2015-03-03 |
EP2565974B1 (en) | 2017-09-20 |
US20130065116A1 (en) | 2013-03-14 |
EP2565974A4 (en) | 2017-01-18 |
EP2565974A1 (en) | 2013-03-06 |
JP5648828B2 (ja) | 2015-01-07 |
KR101455918B1 (ko) | 2014-11-03 |
CN102859781B (zh) | 2015-07-15 |
CN102859781A (zh) | 2013-01-02 |
JP2011233300A (ja) | 2011-11-17 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
JP5648828B2 (ja) | リチウムイオン二次電池 | |
JP6428647B2 (ja) | 非水電解質二次電池及び非水電解質二次電池の製造方法 | |
KR101169947B1 (ko) | 리튬 이차전지용 양극 활물질 | |
KR101154876B1 (ko) | 리튬 이차전지용 양극 활물질 | |
KR101123057B1 (ko) | 리튬 이차전지용 양극 활물질 | |
KR101138637B1 (ko) | 리튬 이차전지용 양극 활물질 | |
KR102301040B1 (ko) | 실리콘계 음극 활물질, 이의 제조방법, 상기 실리콘계 음극 활물질을 포함하는 음극 및 상기 음극을 포함하는 리튬 이차전지 | |
KR101658510B1 (ko) | 이차전지용 양극 및 이를 포함하는 이차전지 | |
WO2012035648A1 (ja) | 非水電解液二次電池用活物質および非水電解液二次電池 | |
KR101637898B1 (ko) | 양극 활물질과 이를 포함하는 리튬 이차전지 | |
KR101774263B1 (ko) | 이차전지용 바인더 및 이를 포함하는 이차전지 | |
KR101147601B1 (ko) | 표면이 개질되어 있는 양극 활물질 | |
JP2008091236A (ja) | 非水電解質二次電池 | |
KR20150083240A (ko) | 하이브리드 스택-폴딩형 전극조립체 및 이를 포함하는 이차전지 | |
KR101515361B1 (ko) | 양극 활물질 및 이를 포함하는 리튬 이차전지 | |
KR101580486B1 (ko) | 젖음성이 향상된 이차전지용 음극 및 이를 포함하는 리튬 이차전지 | |
US9105371B2 (en) | Cathode active material and lithium secondary battery comprising the same | |
KR101301564B1 (ko) | 스피넬 결정구조를 가진 고용량 리튬 망간계 산화물의 이차전지용 양극 및 이를 포함하는 리튬 이차전지 | |
KR20130084362A (ko) | 양극 활물질 및 이를 포함하는 리튬 이차전지 | |
KR101573222B1 (ko) | 복합 음극 활물질 및 이를 포함하는 리튬 이차전지 | |
KR101386150B1 (ko) | 음극활물질 전극 및 그 제조방법 및 이를 구비한 리튬이차전지 | |
KR20130033552A (ko) | 양극 활물질 및 제조방법 | |
KR20150014329A (ko) | 젖음성이 향상된 이차전지용 음극 활물질 및 이를 포함하는 리튬 이차전지 |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
WWE | Wipo information: entry into national phase |
Ref document number: 201180021326.7 Country of ref document: CN |
|
121 | Ep: the epo has been informed by wipo that ep was designated in this application |
Ref document number: 11774715 Country of ref document: EP Kind code of ref document: A1 |
|
DPE1 | Request for preliminary examination filed after expiration of 19th month from priority date (pct application filed from 20040101) | ||
WWE | Wipo information: entry into national phase |
Ref document number: 13643207 Country of ref document: US |
|
ENP | Entry into the national phase |
Ref document number: 20127027907 Country of ref document: KR Kind code of ref document: A |
|
NENP | Non-entry into the national phase |
Ref country code: DE |
|
REEP | Request for entry into the european phase |
Ref document number: 2011774715 Country of ref document: EP |
|
WWE | Wipo information: entry into national phase |
Ref document number: 2011774715 Country of ref document: EP |