JP3719277B2 - Non-aqueous secondary battery - Google Patents

Description

以上の結果から、本発明の電池は明らかに保存中の電圧降下が少なく、性能が安定していることがわかる。
【００６２】
実施例ー２
実施例１の電池Ａ、Ｂと同じ電池をそれぞれ３００個づつ作製し、４．１５Ｖまで充電した。充電不良の電池の個数を求めたところ、比較用の電池Ａでは６個、本発明の電池Ｂでは０個であり、明らかに不良品発生率が改良されていることがわかった。
【００６３】
実施例ー３
実施例ー１で用いた負極材料１−Ａのかわりに、１ーＢから１ーＦを用い実施例ー１と同様な実験を行ったところ、ほぼ実施例ー１と同様な結果が得られた。
実施例ー４
実施例ー１の負極シートｂと正極シートａを組み合わせて電池Ｃを作った。正極シートｂのかわりに、保護層の厚みを変えてシート厚２８０μｍとした正極シートｃと負極シートａとを組み合わせて電池Ｄを作った。これらの電池Ｃ、Ｄを用いて、実施例ー１と同様な実験を行ったところ、電池Ｂ同様に保存後の電圧降下が少なく性能の安定なことがわかった。但し、開路電圧はＣ、Ｄとも電池Ｂよりわずかに低下していた。
実施例−５
実施例−１の負極ａの上に、α−Al₂O₃ （平均粒径１μｍ）９４重量％、鱗片状黒鉛３重量％、カルボキシメチルセルロース３重量％の割合で混合し、水を媒体として混練してスラリー化したものを塗布して作製したものを負極ｃとした。負極シートにｃを使用する以外は電池Ｂと同様に作製した電池をそれぞれＥとした。
電池Ｅを用いて、実施例−１と同様な実験を行ったところ、ほぼ実施例−１と同様な結果が得られた。
実施例−６
実施例−１の負極ａの上に、α−Al₂O₃ （平均粒径１μｍ）９４．５重量％、ポリフッ化ビニリデン４．５重量％、カルボキシメチルセルロース１重量％の割合で混合し、水を媒体として混練してスラリー化したものを塗布して作製したものを負極ｄとした。負極シートにｄを使用する以外は電池Ｂと同様に作製した電池をＦとした。
実施例−１の電池Ｂ、実施例−５の電池Ｅ、電池Ｆをそれぞれ１０個づつ作製し、４．１５−２．８Ｖで充電したとき５mA／cm² での放電容量と１mA／cm² での放電容量を測定し次の結果を得た。表中の放電容量は電池Ｂの容量を１００％としたときの割合で示した。

以上の結果から、本発明の電池は明らかに容量が大きく、５mA／cm² の放電容量／１mA／cm² の放電容量に優れていることがわかる。
実施例−７
実施例−１の負極ａの上に、α−Al₂O₃ （平均粒径１μｍ）９３重量％、鱗片状黒鉛３重量％、ポリフッ化ビニリデン３重量％、カルボキシメチルセルロース１重量％の割合で混合し、水を媒体として混練してスラリー化したものを塗布して作製したものを負極ｄとした。また、実施例−１の正極ａと同様の方法で塗布量のみ減らして厚み２２５μｍの正極とし、これに正極ｂと同様の保護層を付けたものを正極ｄとした。
実施例−５の負極シートｃ及び負極シートｄ上に負極材料１ｇ当たり１２０mgのリチウム金属を短冊状にして貼り付け、正極シートｄを組み合わせる以外は電池Ｂと同様に作製した電池をそれぞれ電池Ｇ、Ｈとした。これをそれぞれ１０個づつ作製し、実施例−６と同様の試験を行い次の結果を得た。表中の放電容量は電池Ｇの容量を１００％としたときの割合で示した。

以上の結果から、本発明の電池は明らかに容量が大きく、５mA／cm² の放電容量／１mA／cm² の放電容量に優れていることがわかる。
【００６４】
本発明のように、リチウムを可逆的に吸蔵放出可能な遷移金属酸化物を含む正極、リチウムを可逆的に吸蔵放出可能な金属酸化物を含む負極、リチウム塩を含む非水電解質、セパレーターから成る非水二次電池において、該負極及び／又は正極が保護層を少なくとも1層有し、該保護層が導電性を持たない固体粒子と導電性粒子とセルロース誘導体、ポリアクリル酸誘導体、ポリビニルアルコール誘導体、ポリエチレンオキシド誘導体、および澱粉から選ばれる水溶性ポリマーからなり、該保護層の厚みが１μｍ以上４０μｍ以下であることによって、高い放電作動電圧、大きな放電容量で保存安定性のある非水二次電池を安定に作ることが出来る。
【図面の簡単な説明】
【図１】実施例に使用した円筒型電池の断面図を示したものである。
【符号の説明】
８ 正極シート
９ 負極シート
１０ セパレーター
１１ 電池缶
１２ 電池蓋
１３ ガスケット
１４ 安全弁[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a non-aqueous secondary battery with improved productivity, high discharge potential, excellent life and safety.
[0002]
[Prior art]
Japanese Patent Application Laid-Open No. 61-7577 describes a protective layer made of a material having both electron conductivity and ion conductivity such as lithium on the surface of the positive electrode, and tungsten, It is stated that oxides of molybdenum and vanadium are preferable. However, these compounds have not yet exhibited a sufficient effect to prevent internal short circuit.
Japanese Patent Application Laid-Open No. 4-28173 describes that a polymer film that selectively permeates the alkali metal ions is disposed on the negative electrode (alkali metal or alkali metal alloy) surface facing the positive electrode. Yes. However, the installation of these porous polymer membranes has a problem of greatly reducing the battery capacity.
[0003]
[Problems to be solved by the invention]
Therefore, an object of the present invention is to improve the productivity of a nonaqueous secondary battery having a high discharge voltage, good charge / discharge cycle characteristics, and excellent safety.
[0004]
[Means for Solving the Problems]
  An object of the present invention is to reversibly store and release lithium.Transition metal oxideIncluding positive electrode,Includes metal oxides that can reversibly store and release lithiumIn a nonaqueous secondary battery comprising a negative electrode, a nonaqueous electrolyte containing a lithium salt, and a separator, the negative electrode and / or the positive electrode has at least one protective layer, and the protective layerNot conductiveSolid particles and conductive particlesSelected from cellulose derivatives, polyacrylic acid derivatives, polyvinyl alcohol derivatives, polyethylene oxide derivatives, and starchIt consists of a water-soluble polymer, and the thickness of the protective layer is1μm to 40μmIt was achieved by a non-aqueous secondary battery characterized by
[0005]
DETAILED DESCRIPTION OF THE INVENTION
  The present inventors can reversibly occlude and release lithium.Transition metal oxideIncluding positive electrode,Includes metal oxides that can reversibly store and release lithiumWe have intensively investigated the cause of poor production rate of non-aqueous secondary batteries consisting of negative electrode, non-aqueous electrolyte containing lithium salt, and separator. During the process from projecting irregularities on the electrode surface, electrode transportation to battery assembly Due to the electrode surface scratches, unevenness due to partial dropout, etc., the separator can be destroyed directly when winding the battery, or the separator can be broken due to subtle sliding during winding or uneven pressure. It was found that the contribution of the occurrence of an internal short circuit is large. In order to prevent these internal short circuits, it is effective to provide a protective layer on the electrode surface, and it has been found that the installation of the protective layer improves the manufacturing yield and also the safety. Furthermore, the protective layerNot conductiveSolid particles and conductive particlesSelected from cellulose derivatives, polyacrylic acid derivatives, polyvinyl alcohol derivatives, polyethylene oxide derivatives, and starchIt consists of a water-soluble polymer, and the thickness of the protective layer is1μm to 40μmThus, it was found that the above can be achieved without a decrease in discharge capacity, particularly at a high current.
[0006]
  Although the preferable aspect of this invention is shown below, this invention is not limited to these.
(1) Reversible storage and release of lithiumTransition metal oxideIncluding positive electrode,Includes metal oxides that can reversibly store and release lithiumIn a nonaqueous secondary battery comprising a negative electrode, a nonaqueous electrolyte containing a lithium salt, and a separator, the negative electrode and / or the positive electrode has at least one protective layer, and the protective layerNot conductiveSolid particles and conductive particlesSelected from cellulose derivatives, polyacrylic acid derivatives, polyvinyl alcohol derivatives, polyethylene oxide derivatives, and starchIt consists of a water-soluble polymer, and the thickness of the protective layer is1μm to 40μmA non-aqueous secondary battery characterized by the above.
(2)The protective layer is formed on the negative electrode (1)A non-aqueous secondary battery according to 1.
(3)The protective layer is formed on the positive electrode (1)A non-aqueous secondary battery according to 1.
(4)The protective layer is formed on both the positive electrode and the negative electrode (1)A non-aqueous secondary battery according to 1.
(5)Any of (1) to (4), wherein the non-conductive solid particles contained in the protective layer are a metal, a carbide of a non-metallic element, a silicide, a nitride, a sulfide, or an oxide.A non-aqueous secondary battery according to 1.
(6)Solid particles having no electrical conductivity contained in the protective layer are inorganic chalcogenide particles (5)A non-aqueous secondary battery according to 1.
(7)The inorganic chalcogenide particles contain at least one oxide of sodium, potassium, magnesium, calcium, strontium, zirconium, aluminum and silicon (6)A non-aqueous secondary battery according to 1.
(8)The oxide according to claim 7 is alumina, silicon dioxide or zirconia (7)The non-aqueous secondary battery as described.
(9)The water-soluble polymer contained in the protective layer is a polyacrylic acid derivative or a cellulose derivative (1)A non-aqueous secondary battery according to 1.
(10)The conductive particles contained in the protective layer are inorganic particles (9)A non-aqueous secondary battery according to 1.
(11) (10)The inorganic particles are metal powder, inorganic chalcogenide, carbonaceous compound (10)A non-aqueous secondary battery according to 1.
(12) (11)The carbonaceous compound is natural graphite or vapor grown carbon(11) The nonaqueous secondary battery according to (11).
[0007]
In the present invention, the protective layer is composed of at least one layer, and may be composed of the same or different layers. The thickness of the protective layer is preferably 1 μm or more and 40 μm or less, more preferably 2 μm or more and 30 μm or less. Further, it is desirable that the protective layer containing these particles does not melt at 300 ° C. or less or does not form a new film. These protective layers include organic or inorganic solid particles having no electrical conductivity, and may also include conductive organic or inorganic solid particles. Of these particles, inorganic solid particles are more preferable.
[0008]
Examples of inorganic particles include carbides, silicides, nitrides, sulfides, and oxides of metals and nonmetallic elements.
Among carbides, silicides, and nitrides, SiC, aluminum nitride (AlN), BN, and BP are preferably highly insulating and chemically stable. Particularly, SiC using BeO, Be, and BN as a sintering aid is preferable. Particularly preferred.
Among chalcogenides, oxides are preferable, and oxides that are not easily oxidized or reduced are preferable. These oxides include Al₂O_Three, As_FourO₆, B₂O_Three, BaO, BeO, CaO, Li₂O, K₂O, Na₂O, In₂O_Three, MgO, Sb₂O_Five, SiO₂, SrO, ZrO₂Can be given. Among these, Al₂O_Three, BaO, BeO, CaO, K₂O, Na₂O, MgO, SiO₂, SrO, ZrO₂Is particularly preferred. These oxides may be single or complex oxides. Preferred compounds as the composite oxide include mullite (3Al₂O_Three・ 2SiO₂), Steatite (MgO.SiO)₂), Forsterite (2MgO · SiO₂), Cordierite (2MgO · 2Al)₂O_Three・ 5SiO₂And the like.
The conductive particles are preferably inorganic particles, and examples thereof include metal powder, inorganic chalcogenide, and carbonaceous compound particles. In particular, carbonaceous compounds, natural graphite, and vapor grown carbon are preferable.
[0009]
These inorganic compound particles are used as particles having a size of 0.1 μm or more and 20 μm or less, particularly preferably 0.2 μm or more and 15 μm or less, by a method such as control of production conditions or pulverization.
[0010]
  The content of particles used in the present invention is 1 to 80 g / m.², Preferably 2 to 40 g / m²It is. The protective layerNot conductiveSolid particles and conductive particlesSelected from cellulose derivatives, polyacrylic acid derivatives, polyvinyl alcohol derivatives, polyethylene oxide derivatives, and starchFormed from a water-soluble polymer. The ratio of the solid particles to the water-soluble polymer is preferably 40% by weight or more and 96% by weight or less, more preferably 50% by weight or more and 92% by weight or less, based on the total weight of both. As the water-soluble polymer, cellulose derivatives and polyacrylic acid derivatives are preferable.
[0011]
The protective layer may be applied to either the positive electrode or the negative electrode, or may be applied to both the positive electrode and the negative electrode. In addition, when the positive electrode or the negative electrode is formed by applying a mixture on both sides of the current collector, the protective layer may be applied on both sides or only on one side. Also good. However, it is necessary to coat either one of the positive electrode and the negative electrode that oppose each other via the separator.
The coating method of the protective layer may be a sequential method in which a protective layer is sequentially coated after a mixture containing a material capable of reversibly occluding and releasing lithium on the current collector, or a mixture layer And a simultaneous application method in which a protective layer is applied simultaneously.
[0012]
The positive and negative electrodes used in the nonaqueous secondary battery of the present invention can be prepared by coating a positive electrode mixture or a negative electrode mixture on a current collector. In addition to the positive electrode active material or the negative electrode material, the positive electrode or the negative electrode mixture can each contain a conductive agent, a binder, a dispersant, a filler, an ionic conductive agent, a pressure enhancer, and various additives.
[0013]
The negative electrode material used in the present invention may be any compound that can occlude and release light metal ions. These include light metals, light metal alloys, carbonaceous compounds, inorganic oxides, inorganic chalcogenides, metal complexes and organic polymer compounds, with carbonaceous compounds, inorganic oxides and inorganic chalcogenides being preferred. Furthermore, these may be used in combination. Examples include light metals and carbonaceous compounds, light metals and inorganic oxides, and combinations of light metals, carbonaceous compounds, and inorganic oxides. These negative electrode materials are preferable because they provide high capacity, high discharge potential, high safety, and high cycle effect. The light metal ion is preferably lithium.
[0014]
The carbonaceous compound is preferably selected from natural graphite, artificial graphite, vapor-grown carbon, baked carbon of an organic substance, and the like, and includes a graphite structure. In addition to carbon, the carbonaceous compound may contain 0 to 10% by weight of a heterogeneous compound such as B, P, N, S, SiC, or B4 C.
[0015]
As an element for forming an oxide or chalcogenide, a transition metal or a metal or a semi-metal element of Group 15 to 15 of the periodic table is preferable.
As the transition metal compound, V, Ti, Fe, Mn, Co, Ni, Zn, W, Mo alone or a composite oxide or chalcogenide is particularly preferable. As a more preferred compound, Li described in JP-A-6-44,972_pCo_qV_1-qO_r(Where p = 0.1 to 2.5, q = 0 to 1, z = 1.3 to 4.5).
[0016]
The metal or metalloid compound other than the transition metal includes a group 13-15 element of the periodic table, Ga, Si, Sn, Ge, Pb, Sb, Bi alone or a combination of two or more thereof. Oxides and chalcogenides are selected.
For example, Ga₂O_Three, SiO, GeO, GeO₂, SnO, SnO₂, SnSiO_Three, PbO, PbO₂, Pb₂O_Three, Pb₂O_Four, Pb_ThreeO_Four, Sb₂O_Three, Sb₂O_Four, Sb₂O_Five, Bi₂O_Three, Bi₂O_Four, Bi₂O_Five, SnSiO_Three, GeS, GeS₂, SnS, SnS₂, PbS, PbS₂, Sb₂S_Three, Sb₂S_Five, SnSiS_ThreeEtc. are preferable. These are also complex oxides with lithium oxide, such as Li₂GeO_Three, Li₂SnO₂It may be.
[0017]
The complex chalcogen compound and complex oxide are preferably mainly amorphous when assembled into a battery. The term “amorphous” as used herein refers to an X-ray diffraction method using CuKα rays, which has a broad scattering band having a peak at 20 ° to 40 ° with a 2θ value, and has a crystalline diffraction line. Also good. Preferably, the strongest intensity of the crystalline diffraction lines seen at 2θ values of 40 ° or more and 70 ° or less is 500 of diffraction line intensities at the apexes of broad scattering bands seen at 20 ° or more and 40 ° or less of 2θ values. It is preferably not more than twice, more preferably not more than 100 times, particularly preferably not more than 5 times, and most preferably not having a crystalline diffraction line.
[0018]
The above complex chalcogen compounds and complex oxides are complex chalcogen compounds and complex oxidations of three or more elements among B, Al, Ga, In, Tl, Si, Ge, Sn, Pb, P, As, Sb and Bi. More preferably, it is a complex oxide.
Particularly preferred is a complex oxide composed of three or more elements of B, Al, Si, Ge, Sn, and P. These composite oxides may contain a group 1 to group 3 element or a halogen element in the periodic table mainly for modifying the amorphous structure.
[0019]
Among the above negative electrode materials, an amorphous composite oxide mainly composed of tin is particularly preferable, and is represented by the following general formula (1).
SnM¹ _aO_t                  General formula (1)
Where M¹Represents two or more elements selected from Al, B, P, Si, Group 1 elements, Group 2 elements, Group 3 elements, and halogen elements in the periodic table, and a is a number of 0.2 or more and 2 or less , T represents a number from 1 to 6.
[0020]
Of the general formula (1), compounds of the following general formula (2) are more preferable.
SnM² _bO_t                  General formula (2)
Where M²Represents two or more elements selected from Al, B, P, Periodic Table Group 1 elements, Group 2 elements, Group 3 elements, and halogen elements, and b represents a number of 0.2 or more and 2 or less, t represents a number from 1 to 6.
[0021]
Of the general formula (1), compounds of the following general formula (3) are more preferable.
SnM^Three _cM^Four _dO_t            General formula (3) In formula, M^ThreeIs at least two of Al, B, P and Si, M^FourRepresents at least one of group 1 element, group 2 element, group 3 element and halogen element in the periodic table, c is a number from 0.2 to 2, d is a number from 0.01 to 1 0.2 <c + d <2, t represents a number of 1 or more and 6 or less.
M^ThreeAnd M^FourIs an element for making the compound of general formula (3) amorphous as a whole, and M^ThreeIs an element that can be amorphized and is preferably used in combination of two or more of Al, B, P, and Si. M^FourIs an element that can be amorphously modified, and is a group 1 element, group 2 element, group 3 element, or halogen element in the periodic table, and K, Na, Cs, Mg, Ca, Ba, Y, F is preferred. b is a number from 0.2 to 2; c is a number from 0.01 to 1; 0.2 <b + c <2; and t is a number from 1 to 6.
[0022]
The amorphous composite oxide of the present invention can employ either a firing method or a solution method, but a firing method is more preferable. In the firing method, it is preferable to obtain an amorphous composite oxide by thoroughly mixing oxides or compounds of the elements described in the general formula (1) and then firing.
[0023]
As firing conditions, the temperature rise rate is preferably 5 ° C. or more and 200 ° C. or less per minute, the firing temperature is preferably 500 ° C. or more and 1500 ° C. or less, and the firing time is 1 hour. It is preferable that it is 100 hours or less. In addition, the temperature decrease rate is 2 ° C. or more per minute and 10⁷It is preferable that it is below ℃.
The rate of temperature increase in the present invention is the average rate of temperature rise from “50% of the firing temperature (indicated in ° C.)” to “80% of the firing temperature (indicated in ° C.)”. It is the average rate of temperature drop from reaching “80% of the firing temperature (indicated by ° C.)” to “50% of the firing temperature (indicated in ° C.)”.
The temperature drop may be cooled in a firing furnace or taken out of the firing furnace and may be cooled, for example, in water. In addition, a super rapid cooling method such as a gun method, a Hammer-Anvil method, a slap method, a gas atomization method, a plasma spray method, a centrifugal quenching method, or a melt drag method described on page 217 of ceramics processing (Gihodo Publishing 1987) can also be used. Moreover, you may cool using the single roller method and the double roller method of New Glass Handbook (Maruzen 1991) p.172. In the case of a material that melts during firing, the fired product may be continuously taken out while supplying raw materials during firing. In the case of a material that melts during firing, it is preferable to stir the melt.
[0024]
The firing gas atmosphere is preferably an atmosphere having an oxygen content of 5% by volume or less, and more preferably an inert gas atmosphere. Examples of the inert gas include nitrogen, argon, helium, krypton, and xenon. The most preferred inert gas is pure argon.
[0025]
As for the average particle size of the compound shown by this invention, 0.1-60 micrometers is preferable. To obtain a predetermined particle size, a well-known pulverizer or classifier is used. For example, a mortar, a ball mill, a sand mill, a vibrating ball mill, a satellite ball mill, a planetary ball mill, a swirling air flow type jet mill, a sieve, or the like is used. When pulverizing, wet pulverization in the presence of water or an organic solvent such as methanol can be performed as necessary. In order to obtain a desired particle size, classification is preferably performed. The classification method is not particularly limited, and a sieve, an air classifier, or the like can be used as necessary. Classification can be used both dry and wet.
[0026]
Although the example of the negative electrode material of this invention is shown below, this invention is not limited to these.
SnB_0.5P_0.5O_Three, SnAl_0.3B_0.5P_0.2O_2.7, SnAl_0.3B_0.7O_2.5, SnSi_0.8P_0.2O_3.1, SnSi_0.8B_0.2O_2.9, SnSi_0.8Al_0.2O_2.9, SnSi_0.6Al_0.2B_0.2O_2.8, SnSi_0.6Al_0.2P_0.2O_Three, SnSi_0.6B_0.2P_0.2O_Three, SnSi_0.4Al_0.2B_0.4O_2.7, SnSi_0.6Al_0.1B_0.1P_0.3O_3.25, SnSi_0.6Al_0.1B_0.3P_0.1O_3.05, SnSi_0.5Al_0.3B_0.4P_0.2O_3.55, SnSi_0.5Al_0.3B_0.4P_0.5O_4.30, SnSi_0.8Al_0.3B_0.2P_0.2O_3.85, SnAl_0.1B_0.5P_0.5Mg_0.1F_0.2O_3.15
[0027]
SnSi_0.8Mg_0.2O_2.8, SnSi_0.6Al_0.2Mg_0.2O_2.7, SnSi_0.6Al_0.1B_0.2Mg_0.2O_2.85, SnSi_0.8Ca_0.2O_2.8, SnSi_0.6Al_0.2Ca_0.2O_2.7, SnSi_0.6Al_0.1B_0.1P_0.1Ca_0.2O_2.95, SnSi_0.5Al_0.2B_0.1P_0.1Mg_0.1O_2.8, SnSi_0.5Al_0.1B_0.2P_0.1Ca_0.4O_3.1, SnSi_0.8Ba_0.2O_2.8, SnSi_0.6Al_0.1B_0.1P_0.1Ba_0.2O_2.95.
[0028]
Sn_0.9Mn_0.3B_0.4P_0.4Ca_0.1Rb_0.1O_2.95, Sn_0.9Fe_0.3B_0.4P_0.4Ca_0.1Rb_0.1O_2.95, Sn_0.8Pb_0.2Ca_0.1P_0.9O_3.35, Sn_0.3Ge_0.7Ba_0.1P_0.9O_3.35, Sn_0.9Mn_0.1Mg_0.1P_0.9O_3.35, Sn_0.2Mn_0.8Mg_0.1P_0.9O_3.35, Sn_0.7Pb_0.3Ca_0.1P_0.9O_3.35, Sn_0.2Ge_0.8Ba_0.1P_0.9O_3.35.
[0029]
Sn_1.6B_0.4P_0.4Ca_0.2O_3.4, Sn_1.3B_0.4P_0.4Ca_0.2O_3.1, Sn_1.6B_FourP_0.4Ba_0.2O_3.4, Sn_1.3B_0.4P_0.4Ba_0.2O_3.1, Sn_1.6B_0.4P_0.4Mg_0.2O_3.4, Sn_1.6Al_0.1B_0.3P_0.4Ca_0.2O_3.4,
[0030]
Sn_1.3Al_0.1B_0.3P_0.4K_0.2O_Three, Sn_1.0Al_0.1B_0.3P_0.4K_0.2O_2.7, Sn_1.6Al_0.1B_0.3P_0.4Na_0.2O_3.3, Sn_1.3Al_0.1B_0.3P_0.4Na_0.2O_Three, Sn_1.0Al_0.1B_0.3P_0.4Na_0.2O_2.7, Sn_1.6Al_0.1B_0.3P_0.4Rb_0.2O_3.3, Sn_1.3Al_0.1B_0.3P_0.4Rb_0.2O_Three, Sn_1.0Al_0.1B_0.3P_0.4Rb_0.2O_2.7, Sn_1.6Al_0.1B_0.3P_0.4Cs_0.2O_3.3, Sn_1.2Al_0.1B_0.3P_0.4Cs_0.2O_2.9, Sn_1.0Al_0.1B_0.3P_0.4Cs_0.2O_2.7, Sn_1.3Al_0.1B_0.3P_0.4Ba_0.1K_0.1O_3.05.
[0031]
The chemical formula of the compound obtained by firing can be calculated from the weight difference between the powders before and after firing as an inductively coupled plasma (ICP) emission spectroscopic analysis method as a measurement method.
[0032]
The amount of light metal inserted into the negative electrode material of the present invention may be close to the precipitation potential of the light metal, but for example, it is preferably 50 to 700 mol%, particularly preferably 100 to 600 mol% per negative electrode material. It is preferable that the release amount be larger than the insertion amount. The light metal insertion method is preferably an electrochemical, chemical or thermal method. The electrochemical method is preferably a method in which a light metal contained in the positive electrode active material is inserted electrochemically or a method in which the light metal or an alloy thereof is directly inserted electrochemically. Chemical methods include mixing with light metals, contact, or reacting with an organic metal such as butyllithium. Electrochemical methods and chemical methods are preferred. The light metal is particularly preferably lithium or lithium ion.
[0033]
Various elements can be included in the negative electrode material of the present invention. For example, it may contain dopants of lanthanoid metals (Hf, Ta, W, Re, Os, Ir, Pt, Au, Hg) and various compounds that increase electron conductivity (for example, compounds of Sb, In, and Nb). . The amount of the compound to be added is preferably 0 to 5 mol%.
[0034]
The surface of the positive electrode active material or negative electrode material of the oxide used in the present invention can be coated with an oxide having a chemical formula different from that of the positive electrode active material or negative electrode material used. The surface oxide is preferably an oxide containing a compound that dissolves both acidic and alkaline. Furthermore, a metal oxide with high electron conductivity is preferable. For example, PbO₂, Fe₂O_Three, SnO₂, In₂O_ThreeZnO, or these oxides or a dopant (for example, a metal having a different valence or a halogen element in the oxide) is preferably included. Particularly preferably, SiO₂, SnO₂, Fe₂O_ThreeZnO and PbO. The amount of the metal oxide used in these surface treatments is preferably 0.1 to 10% by weight, particularly preferably 0.2 to 5% by weight, and preferably 0.3 to 3% per positive electrode active material / negative electrode material. Weight percent is most preferred.
In addition, the surface of the positive electrode active material or the negative electrode material can be modified. For example, the surface of the metal oxide may be treated with an esterifying agent, treated with a chelating agent, treated with a conductive polymer, polyethylene oxide, or the like.
[0035]
The positive electrode active material used in the present invention may be a transition metal oxide capable of reversibly inserting and releasing lithium ions, but a lithium-containing transition metal oxide is particularly preferable. Preferred lithium-containing transition metal oxide positive electrode active materials used in the present invention include oxides containing lithium-containing Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Mo, and W. Further, alkali metals other than lithium (elements IA and IIA in the periodic table) and / or Al, Ga, In, Ge, Sn, Pb, Sb, Bi, Si, P, B, etc. may be mixed. . The mixing amount is preferably 0 to 30 mol% with respect to the transition metal.
More preferable lithium-containing transition metal oxide positive electrode active materials used in the present invention include lithium compounds / transition metal compounds (wherein transition metals are Ti, V, Cr, Mn, Fe, Co, Ni, Mo, W) It is preferable to synthesize by mixing so that the total molar ratio of at least one selected from (1) is 0.3 to 2.2.
A particularly preferable lithium-containing transition metal oxide positive electrode active material used in the present invention is a lithium compound / transition metal compound (where the transition metal is at least one selected from V, Cr, Mn, Fe, Co, Ni). It is preferable to synthesize by mixing so that the total molar ratio of
A particularly preferable lithium-containing transition metal oxide positive electrode active material used in the present invention is Lix QOy (where Q is a transition metal mainly containing at least one of Co, Mn, Ni, V and Fe), x = 0. 0.2 to 1.2 and y = 1.4 to 3). As Q, in addition to the transition metal, Al, Ga, In, Ge, Sn, Pb, Sb, Bi, Si, P, B, or the like may be mixed. The mixing amount is preferably 0 to 30 mol% with respect to the transition metal.
[0036]
As a more preferred lithium-containing metal oxide positive electrode active material used in the present invention, Li_xCoO₂, Li_xNiO₂, Li_xMnO₂, Li_xCo_aNi_1-aO₂, Li_zCo_bV_1-bO_z, Li_xCo_bFe_1-bO₂, Li_xMn₂O_Four, Li_xMn_cCo_2-cO_Four, Li_xMn_cNi_2-cO_Four, Li_xMn_cV_2-cO_z, Li_xMn_cFe_2-cO_Four, Li_xCo_bB_1-bO₂, Li_xCo_bSi_1-bO₂, Li_xMn₂O_FourAnd MnO₂A mixture of Li_2xMnO_ThreeAnd MnO₂A mixture of Li_xMn₂O_Four, Li_2xMnO_ThreeAnd MnO₂(Where x = 0.2 to 1.2, a = 0.1 to 0.9, b = 0.8 to 0.98, c = 1.6 to 1.96, z = 2.01) To 5).
As a more preferred lithium-containing metal oxide positive electrode active material used in the present invention, Li_xCoO₂, Li_xNiO₂, Li_xMnO₂, Li_xCo_aNi_1-aO₂, Li_xCo_bV_1-bO_z, Li_xCo_bFe_1-bO₂, Li_xMn₂O_Four, Li_xMn_cCo_2-cO_Four, Li_xMn_cNi_2-cO_Four, Li_xMn_cV_2-cO_Four, Li_xMn_cFe_2-cO_Four(Where x = 0.7 to 1.2, a = 0.1 to 0.9, b = 0.8 to 0.98, c = 1.6 to 1.96, z = 2.1-2. .3).
As the most preferable lithium-containing transition metal oxide positive electrode active material used in the present invention, Li_xCoO₂, Li_xNiO₂, Li_xMnO₂, Li_xCo_aNi_{1- a}O₂, Li_xMn₂O_Four, Li_xCo_bV_1-bO_z(Where x = 0.7 to 1.2, a = 0.1 to 0.9, b = 0.9 to 0.98, z = 2.02 to 2.3). Here, said x value is a value before the start of charging / discharging, and it increases / decreases by charging / discharging.
[0037]
The positive electrode active material can be synthesized by a method in which a lithium compound and a transition metal compound are mixed and fired, or by a solution reaction, and the firing method is particularly preferable. The firing temperature used in the present invention may be a temperature at which a part of the mixed compound used in the present invention is decomposed and melted, and is preferably 250 to 2000 ° C, particularly preferably 350 to 1500 ° C. In firing, it is preferably calcined at 250 to 900 ° C. The firing time is preferably 1 to 72 hours, more preferably 2 to 20 hours. The raw material mixing method may be dry or wet. Moreover, you may anneal at 200 to 900 degreeC after baking.
The firing gas atmosphere is not particularly limited and can be either an oxidizing atmosphere or a reducing atmosphere. For example, in the air or a gas whose oxygen concentration is adjusted to an arbitrary ratio, hydrogen, carbon monoxide, nitrogen, argon, helium, krypton, xenon, carbon dioxide, or the like can be given.
[0038]
In synthesizing the positive electrode active material of the present invention, a method of chemically inserting lithium ions into the transition metal oxide is preferably a method of synthesizing lithium metal, a lithium alloy or butyl lithium by reacting with the transition metal oxide. .
The average particle size of the positive electrode active material used in the present invention is not particularly limited, but is preferably 0.1 to 50 μm. Although it does not specifically limit as a specific surface area, it is 0.01-50m in BET method²/ G is preferred. The pH of the supernatant when 5 g of the positive electrode active material is dissolved in 100 ml of distilled water is preferably 7 or more and 12 or less.
To obtain a predetermined particle size, a well-known pulverizer or classifier is used. For example, a mortar, a ball mill, a vibration ball mill, a vibration mill, a satellite ball mill, a planetary ball mill, a swirling air flow type jet mill, a sieve, or the like is used.
The positive electrode active material obtained by firing may be used after being washed with water, an acidic aqueous solution, an alkaline aqueous solution, or an organic solvent.
[0039]
The combination of the negative electrode material and the positive electrode active material used in the present invention is preferably a compound represented by the general formula (1) and Li_xCoO₂, Li_xNiO₂, Li_xCo_aNi_1-aO₂, Li_xMnO₂, Li_xMn₂O_FourOr Li_xCo_bV_1-bO_z(Where x = 0.7 to 1.2, a = 0.1 to 0.9, b = 0.9 to 0.98, z = 2.02 to 2.3) and high discharge A non-aqueous secondary battery having excellent voltage and high capacity and charge / discharge cycle characteristics can be obtained.
[0040]
The equivalent amount of lithium inserted into the negative electrode material of the present invention is 3 to 10 equivalents, and the usage ratio with the positive electrode active material is determined according to this equivalent amount. It is preferable to use the amount ratio based on this equivalent by a factor of 0.5 to 2 times. When the lithium supply source is other than the positive electrode active material (for example, lithium metal, alloy, butyl lithium, etc.), the usage amount of the positive electrode active material is determined in accordance with the lithium release equivalent of the negative electrode material. Also at this time, it is preferable to use a ratio of the amount used based on this equivalent by a factor of 0.5 to 2 times.
[0041]
When lithium is inserted into the negative electrode from a lithium supply source other than the positive electrode in advance, the lithium supply source includes lithium metal, lithium alloy (Al, Al—Mn, Al—Mg, Al—Sn, Al—In, Al It is preferable to use a foil or metal powder of an alloy of -Cd and lithium. These metal foils and the like may be positioned directly on the negative electrode mixture or via the protective layer of the present invention. Moreover, you may locate on the electrical power collector without a negative mix. A thin foil of about 20 μm may be uniformly applied, or a thicker foil may be partially arranged. The thickness of the foil can be determined from the amount that is naturally inserted into the negative electrode after the battery is formed.
[0042]
A conductive agent, a binder, a filler, or the like can be added to the electrode mixture. The conductive agent may be anything as long as it is an electron conductive material that does not cause a chemical change in the constructed battery. Usually, natural graphite (such as scaly graphite, scaly graphite, earthy graphite), artificial graphite, carbon black, acetylene black, ketjen black, carbon fiber or metal (copper, nickel, aluminum, silver, etc.) powder, metal Conductive materials such as fibers or polyphenylene derivatives can be included as one type or as a mixture thereof. The combined use of graphite and acetylene black is particularly preferred. The addition amount is preferably 1 to 50% by weight, particularly preferably 2 to 30% by weight. In the case of carbon or graphite, 2 to 15% by weight is particularly preferable.
[0043]
The binder is usually starch, polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, regenerated cellulose, diacetyl cellulose, polyvinyl chloride, polyvinyl pyrrolidone, tetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, ethylene-propylene-di. Enter polymers (EPDM), sulfonated EPDM, styrene butadiene rubber, polybutadiene, fluoro rubber, polyethylene oxide and other polysaccharides, thermoplastic resins, rubber elastic polymers, and the like are used as one kind or a mixture thereof. Moreover, when using the compound containing a functional group which reacts with lithium like a polysaccharide, it is preferable to add the compound like an isocyanate group and to deactivate the functional group, for example. The amount of the binder added is preferably 1 to 50% by weight, and particularly preferably 2 to 30% by weight.
Any filler can be used as long as it is a fibrous material that does not cause a chemical change in the constructed battery. Usually, olefin polymers such as polypropylene and polyethylene, fibers such as glass and carbon are used. Although the addition amount of a filler is not specifically limited, 0 to 30 weight% is preferable.
[0044]
In using the negative electrode material of the present invention in a non-aqueous secondary battery system, an aqueous dispersion mixture paste containing the compound of the present invention is applied and dried on a current collector, and the pH of the aqueous dispersion mixture paste is It is preferably 5 or more and less than 10, more preferably 6 or more and less than 9. In addition, it is preferable that the temperature of the water-dispersed paste is kept at 5 ° C. or higher and lower than 80 ° C., and is applied onto the current collector within 7 days after the paste is prepared.
[0045]
As the separator, a material having a large ion permeability, a predetermined mechanical strength, and an insulating microporous or gap is used. Furthermore, in order to improve safety, it is necessary to have a function of blocking the current by closing the gaps at 80 ° C. or higher to increase resistance. The closing temperature of these gaps is 90 ° C. or higher and 180 ° C. or lower, more preferably 110 ° C. or higher and 170 ° C. or lower.
The method of creating the gap varies depending on the material, but any known method may be used. In the case of a porous film, the shape of the hole is usually circular or elliptical, and the size is 0.05 μm to 30 μm, preferably 0.1 μm to 20 μm. Furthermore, it may be a rod-like or irregular-shaped hole as in the case of making by a stretching method or a phase separation method. In the case of cloth, the gap is a gap between fibers and depends on how to make a woven or non-woven fabric. The proportion of these gaps, that is, the porosity, is 20% to 90%, preferably 35% to 80%.
[0046]
The separator of the present invention is a cloth such as a microporous film, a woven fabric or a non-woven fabric having a thickness of 5 μm to 100 μm, more preferably 10 μm to 80 μm.
The separator of the present invention preferably contains at least 20% by weight of an ethylene component, and particularly preferably contains 30% or more. Examples of components other than ethylene include propylene, butene, hexene, ethylene fluoride, vinyl chloride, vinyl acetate, and acetalized vinyl alcohol, with propylene and ethylene fluoride being particularly preferred.
The microporous film is preferably made of polyethylene, ethylene-propylene copolymer or ethylene-butene copolymer. Further, those prepared by mixing and dissolving polyethylene and polypropylene, or polyethylene and polytetrafluoroethylene are also preferred.
Nonwoven fabrics and woven fabrics have a thread diameter of 0.1 μm to 5 μm, polyethylene, ethylene-propylene copolymer, ethylene-butene 1 copolymer, ethylene-methylbutene copolymer, ethylene-methylpentene copolymer, polypropylene, Those made of polytetrafluoroethylene fiber yarn are preferred.
These separators may be a single material or a composite material. In particular, a composite of two or more types of microporous films with different pore sizes, porosity and pore closing temperature, etc., microporous films and nonwoven fabrics, microporous films and woven fabrics, and nonwoven fabrics and papers. That is particularly preferred.
The separator of the present invention may contain inorganic fibers such as glass fibers and carbon fibers, and inorganic particles such as silicon dioxide, zeolite, alumina and talc. Further, the voids and the surface may be hydrophilized by treatment with a surfactant.
[0047]
Examples of the electrolyte include organic solvents such as propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, γ-butyrolactone, 1,2-dimethoxyethane, tetrahydrofuran, 2-methyltetrahydrofuran, dimethylsulfate. Foxide, 1,3-dioxolane, formamide, dimethylformamide, dioxolane, acetonitrile, nitromethane, methyl formate, methyl acetate, methyl propionate, ethyl propionate, phosphate triester, trimethoxymethane, dioxolane derivative, sulfolane, 3- Less aprotic organic solvents such as methyl-2-oxazolidinone, propylene carbonate derivatives, tetrahydrofuran derivatives, diethyl ether, 1,3-propane sultone With a lithium salt soluble solvent obtained by mixing one or more and in the solvent, for example, LiClO_Four, LiBF_Four, LiPF₆, LiCF_ThreeSO_Three, LiCF_ThreeCO₂, LiAsF₆, LiSbF₆, LiB_TenCl_Ten, Lower aliphatic lithium carboxylate, LiAlCl_Four, LiCl, LiBr, LiI, chloroborane lithium, lithium tetraphenylborate and the like. In particular, a mixture of propylene carbonate or ethylene carbonate and 1,2-dimethoxyethane and / or diethyl carbonate is mixed with LiCF._ThreeSO_ThreeLiClO_Four, LiBF_FourAnd / or LiPF₆An electrolytic solution containing is preferable. LiBF mixed with ethylene carbonate and diethyl carbonate_FourAnd / or LiPF₆An electrolyte solution containing is particularly preferred.
The amount of these electrolytes added to the battery is not particularly limited, but a necessary amount can be used depending on the amount of the positive electrode active material and the negative electrode material and the size of the battery. The concentration of the supporting electrolyte is preferably 0.2 to 3 mol per liter of the electrolytic solution.
[0048]
In addition to the electrolytic solution, the following solid electrolyte can also be used. The solid electrolyte is classified into an inorganic solid electrolyte and an organic solid electrolyte. Well-known inorganic solid electrolytes include Li nitrides, halides, oxyacid salts, and the like. Among them, Li_ThreeN, LiI, Li_FiveNI₂, Li_ThreeN-LiI-LiOH, LiSiO_FourLiSiO_Four-LiI-LiOH, xLi_ThreePO_Four-(1-x) Li_FourSiO_Four, Li₂SiS_ThreeIn addition, phosphorus sulfide compounds are effective.
In the organic solid electrolyte, a polyethylene oxide derivative or a polymer containing the derivative, a polypropylene oxide derivative or a polymer containing the derivative, a polymer containing an ion dissociation group, a polymer containing an ion dissociation group, and the above aprotic electrolyte Mixtures and phosphate ester polymers are effective.
Furthermore, there is a method of adding polyacrylonitrile to the electrolytic solution. A method of using an inorganic and organic solid electrolyte in combination is also known.
[0049]
As the separator, an insulating thin film having a large ion permeability and a predetermined mechanical strength is used. Sheets and non-woven fabrics made from olefin polymers such as polypropylene, glass fibers or polyethylene are used because of their organic solvent resistance and hydrophobicity. As the pore diameter of the separator, a range generally used for batteries is used. For example, 0.01 to 10 μm is used. The thickness of the separator is generally used in the battery range. For example, 5 to 300 μm is used.
It is also known to add the following compounds to the electrolyte for the purpose of improving discharge and charge / discharge characteristics. For example, pyridine, triethyl phosphite, triethanolamine, cyclic ether, ethylenediamine, n-glyme, hexaphosphoric triamide, nitrobenzene derivative, sulfur, quinoneimine dye, N-substituted oxazolidinone and N, N′-substituted imidazolidinone, Ethylene glycol dialkyl ether, quaternary ammonium salt, polyethylene glycol, pyrrole, 2-methoxyethanol, AlCl_Three, Conductive polymer electrode active material monomer, triethylenephosphoramide, trialkylphosphine, morpholine, aryl compounds with carbonyl group, hexamethylphosphoric triamide and 4-alkylmorpholine, bicyclic And tertiary amines, oils (Japanese Patent Laid-Open No. 62-287,580), quaternary phosphonium salts, tertiary sulfonium salts, and the like.
[0050]
In order to make the electrolyte nonflammable, a halogen-containing solvent such as carbon tetrachloride or ethylene trifluoride chloride can be contained in the electrolyte. In addition, carbon dioxide gas can be included in the electrolyte in order to make it suitable for high-temperature storage. Further, the mixture of the positive electrode and the negative electrode can contain an electrolytic solution or an electrolyte. For example, a method is known in which the ion conductive polymer, nitromethane, or electrolyte is included.
[0051]
The positive and negative electrode current collectors may be anything as long as they are electronic conductors that do not cause a chemical change in the constructed battery. For example, a material obtained by treating the surface of aluminum or stainless steel with carbon, nickel, titanium, or silver in addition to stainless steel, nickel, aluminum, titanium, carbon, or the like as a material is used for the positive electrode.
In particular, aluminum or an aluminum alloy is preferable. For the negative electrode, in addition to stainless steel, nickel, copper, titanium, aluminum, carbon, etc., the surface of copper or stainless steel treated with carbon, nickel, titanium or silver, Al-Cd alloy, etc. are used. It is done. In particular, copper or a copper alloy is preferable. Oxidizing the surface of these materials is also used. Further, it is desirable to make the current collector surface uneven by surface treatment. As the shape, a film, a sheet, a net, a punched product, a lath body, a porous body, a foamed body, a molded body of a fiber group, and the like are used in addition to the foil. The thickness is not particularly limited, but a thickness of 1 to 500 μm is used.
[0052]
The battery shape can be applied to any of coins, buttons, sheets, cylinders, flats, corners, and the like. When the shape of the battery is a coin or button, the positive electrode active material or the negative electrode material mixture is mainly used after being compressed into a pellet shape. The thickness and diameter of the pellet are determined by the size of the battery. Moreover, when the shape of the battery is a sheet, cylinder, or corner, the positive electrode active material or the negative electrode material mixture is mainly used after being applied (coated), dried and compressed on the current collector. As a coating method, a general method can be used. Examples thereof include a reverse roll method, a direct roll method, a blade method, a knife method, an extrusion method, a curtain method, a gravure method, a bar method, a dip method, and a squeeze method. Of these, blade method, knife method and extrusion method are preferred. The application is preferably performed at a speed of 0.1 to 100 m / min. Under the present circumstances, the surface state of a favorable coating layer can be obtained by selecting the said application | coating method according to the solution physical property and dryness of a mixture. The application may be performed one side at a time or simultaneously on both sides. The application may be continuous, intermittent, or striped. Although the thickness, length, and width of the coating layer are determined by the size of the battery, the thickness of the coating layer on one side is particularly preferably 1 to 2000 μm in a compressed state after drying.
[0053]
As a method for drying or dehydrating pellets and sheets, a generally adopted method can be used. In particular, it is preferable to use hot air, vacuum, infrared rays, far infrared rays, electron beams and low-humidity air alone or in combination. The temperature is preferably in the range of 80 to 350 ° C, particularly preferably in the range of 100 to 250 ° C. The water content is preferably 2000 ppm or less for the entire battery, and preferably 500 ppm or less for each of the positive electrode mixture, the negative electrode mixture, and the electrolyte in terms of cycleability. As a pressing method for pellets and sheets, a generally adopted method can be used, and a die pressing method and a calendar pressing method are particularly preferable. The pressing pressure is not particularly limited, but is 0.2 to 3 t / cm.²Is preferred. The press speed of the calendar press method is preferably 0.1 to 50 m / min, and the press temperature is preferably room temperature to 200 ° C. The ratio of the negative electrode sheet width to the positive electrode sheet is preferably 0.9 to 1.1, particularly preferably 0.95 to 1.0. The content ratio of the positive electrode active material and the negative electrode material varies depending on the compound type and the mixture formulation, and thus cannot be limited, but can be set to an optimal value from the viewpoint of capacity, cycle performance, and safety.
[0054]
After the mixture sheet and the separator are overlapped, the sheets are rolled or folded and inserted into the can, the can and the sheet are electrically connected, the electrolyte is injected, and the sealing plate Is used to form a battery can. At this time, the safety valve can be used as a sealing plate. In addition to the safety valve, various conventionally known safety elements may be provided. For example, a fuse, bimetal, PTC element, or the like is used as the overcurrent prevention element. In addition to the safety valve, as a countermeasure against the increase in internal pressure of the battery can, a method of cutting the battery can, a method of cracking the gasket, a method of cracking the sealing plate, or a method of cutting the lead plate can be used. Further, the charger may be provided with a protection circuit incorporating measures against overcharge and overdischarge, or may be connected independently.
In addition, as a measure against overcharging, a method of cutting off current by increasing the battery internal pressure can be provided. At this time, a compound for increasing the internal pressure can be contained in the mixture or the electrolyte. Examples of compounds used to increase internal pressure include Li₂CO_Three, LiHCO_Three, Na₂CO_ThreeNaHCO_Three, CaCO_Three, MgCO_ThreeAnd carbonates.
[0055]
For the can and lead plate, a metal or alloy having electrical conductivity can be used. For example, metals such as iron, nickel, titanium, chromium, molybdenum, copper, and aluminum, or alloys thereof are used. As a method for welding the cap, the can, the sheet, and the lead plate, a known method (eg, direct current or alternating current electric welding, laser welding, ultrasonic welding) can be used. As the sealing agent for sealing, a conventionally known compound or mixture such as asphalt can be used.
[0056]
The use of the non-aqueous secondary battery of the present invention is not particularly limited. For example, when mounted on an electronic device, a color notebook computer, a monochrome notebook computer, a pen input computer, a pocket (palmtop) computer, a notebook word processor, Pocket word processor, e-book player, mobile phone, cordless phone, pager, handy terminal, mobile fax, mobile copy, mobile printer, headphone stereo, video movie, LCD TV, handy cleaner, portable CD, mini-disc, electric shaver, Electronic translators, car phones, transceivers, power tools, electronic notebooks, calculators, memory cards, tape recorders, radios, backup power supplies, memory cards, etc. Others for consumer use include automobiles, electric vehicles, motors, lighting equipment, toys, game equipment, road conditioners, irons, watches, strobes, cameras, medical equipment (pacemakers, hearing aids, shoulder massagers, etc.). Furthermore, it can be used for various military use and space use. Moreover, it can also combine with a solar cell.
[0057]
【Example】
Hereinafter, the present invention will be described in more detail with reference to specific examples. However, the present invention is not limited to the examples unless it exceeds the gist of the invention.
[0058]
Synthesis Example-1
13.5 g of tin monoxide, 3.6 g of silicon dioxide, 0.64 g of magnesium oxide, and 0.69 g of boron oxide were dry-mixed, placed in an alumina crucible, and heated to 1000 ° C. at 15 ° C./min in an argon atmosphere. . After firing at 1200 ° C. for 10 hours, the temperature was lowered to room temperature at 10 ° C./minute, taken out from the firing furnace, coarsely pulverized, and further pulverized by a jet mill, SnSi having an average particle size of 4.5 μm₀.₆Mg_0.2B_0.2O_2.7(Compound 1-A) was obtained. In addition, in the X-ray diffraction method using CuKα ray, it has a broad peak having a peak at around 28 ° at 2θ value, and crystalline diffraction lines are seen at 2θ value from 40 ° to 70 °. There wasn't.
[0059]
In the same manner, stoichiometric amounts of raw materials were mixed, baked and pulverized to obtain the following compounds. SnSi_0.8Mg_0.2O_2.8(1-B), SnSi_0.6Al_0.2Mg_0.2O_2.7(1-C), SnSi_0.6P_0.2Mg_0.2O_2.9(1-D), SnSi_0.6Al_0.1B_0.2Mg_0.1O_2.75(1-E), SnSi_0.5P_0.1B_0.1Mg_0.3O_2.7(1-F).
[0060]
Example-1
As a negative electrode material, the compound 1-A synthesized in Synthesis Example 1 was mixed at a ratio of 88 wt% and scaly graphite 6 wt%, and an aqueous dispersion of polyvinylidene fluoride as a binder was further mixed. 4% by weight, 1% by weight of carboxymethylcellulose and 1% by weight of lithium acetate were added and kneaded using water as a medium to prepare a slurry. The slurry was applied to both sides of a copper foil having a thickness of 18 μm by an extrusion method to produce a negative electrode a.
The negative electrode b is formed on the negative electrode a by α-Al₂O_Three(Mean particle diameter 1 μm) The mixture was mixed at a ratio of 97% by weight and carboxymethyl cellulose 3% by weight, and kneaded with water as a medium to prepare a slurry.
These negative electrodes a and b were dried and then compression-molded with a calendar press, and cut into predetermined widths and lengths to produce strip-shaped negative electrode sheets a and b, respectively. The thickness of the negative electrode sheet was 78 μm for the negative electrode sheet a and 100 μm for the negative electrode sheet b.
LiCoO as positive electrode material₂87% by weight, 6% by weight of flake graphite, 3% by weight of acetylene black, 3% by weight of polytetrafluoroethylene aqueous dispersion and 1% by weight of sodium polyacrylate as a binder, and kneaded using water as a medium The slurry obtained in this manner was applied to both sides of an aluminum foil having a thickness of 20 μm by the same method as above to produce a positive electrode a.
The positive electrode b is formed on the positive electrode a by α-Al₂O_Three(Mean particle diameter 1 μm) The mixture was mixed at a ratio of 97% by weight and carboxymethyl cellulose 3% by weight, and kneaded with water as a medium to prepare a slurry.
These positive electrodes a and b were dried, pressed and cut to produce positive electrode sheets a and b. The thickness of the positive electrode sheet was 250 μm for the positive electrode sheet a and 265 μm for the positive electrode sheet b.
A negative electrode sheet a and a positive electrode sheet a, a negative electrode sheet b and a positive electrode sheet b were combined, and a battery A (for comparison) and a battery B (present invention) were produced by the method described below. Nickel and aluminum lead plates were spot welded to the respective ends of the negative electrode sheet and the positive electrode sheet, and then dehydrated and dried at 150 ° C. for 2 hours in dry air having a dew point of −40 ° C. or lower.
Furthermore, a dehydrated and dried positive electrode sheet (8), a microporous polypropylene film separator (Celgard 2400), a dehydrated and dried negative electrode sheet (9), and a separator (10) were laminated in this order, and this was wound in a spiral shape by a winding machine. Turned.
[0061]
The wound body was housed in a nickel-plated iron-bottomed cylindrical battery can (11) that also serves as a negative electrode terminal. LiPF per liter₆And LiBF_FourIn an amount of 0.95 and 0.05 mol respectively, and an electrolyte composed of a 2: 8 volume mixture of ethylene carbonate and diethyl carbonate was injected into the battery can. A battery lid (12) having a positive electrode terminal was caulked through a gasket (13) to produce a cylindrical battery. The positive electrode terminal (12) was connected to the positive electrode sheet (8), and the battery can (11) was connected to the negative electrode sheet (9) in advance by a lead terminal. FIG. 1 shows a cross section of a cylindrical battery. (14) is a safety valve.
10 batteries A (for comparison) and 10 batteries B (invention) were prepared, 1 mA / cm²And then stored at 60 ° C. for 3 weeks. Three weeks later, the open circuit voltage of each battery was measured, and the following results were obtained.

From the above results, it can be seen that the battery of the present invention clearly has little voltage drop during storage and has stable performance.
[0062]
Example-2
300 pieces of the same batteries as the batteries A and B of Example 1 were prepared and charged to 4.15V. When the number of poorly charged batteries was determined, it was 6 for the comparative battery A and 0 for the battery B of the present invention, and it was found that the defective product occurrence rate was clearly improved.
[0063]
Example-3
When an experiment similar to that of Example-1 was performed using 1-B to 1-F instead of the negative electrode material 1-A used in Example-1, almost the same result as in Example-1 was obtained. It was.
Example-4
A battery C was prepared by combining the negative electrode sheet b and the positive electrode sheet a of Example-1. Instead of the positive electrode sheet b, a battery D was prepared by combining the positive electrode sheet c and the negative electrode sheet a with a sheet thickness of 280 μm by changing the thickness of the protective layer. When these batteries C and D were used, the same experiment as in Example 1 was performed. As with the battery B, it was found that the voltage drop after storage was small and the performance was stable. However, the open circuit voltage was slightly lower than that of the battery B for both C and D.
Example-5
On the negative electrode a of Example-1, α-Al₂O_Three(Non-particle diameter: 1 μm) 94% by weight, 3% by weight of flake graphite, 3% by weight of carboxymethylcellulose were mixed and mixed to form a slurry using water as a medium. did. The batteries produced in the same manner as the battery B except that c was used for the negative electrode sheet were designated E.
When the experiment similar to Example-1 was performed using the battery E, the result almost the same as Example-1 was obtained.
Example-6
On the negative electrode a of Example-1, α-Al₂O_Three(Average particle size 1 μm) 94.5% by weight, polyvinylidene fluoride 4.5% by weight, carboxymethylcellulose 1% by weight, mixed and kneaded using water as a medium to prepare a slurry Was the negative electrode d. A battery produced in the same manner as Battery B, except that d was used for the negative electrode sheet, was designated as F.
10 B batteries of Example-1 and 10 batteries E and F of Example-5 were prepared and charged at 4.15 to 2.8 V, 5 mA / cm.²Discharge capacity and 1mA / cm²The discharge capacity was measured and the following results were obtained. The discharge capacity in the table is shown as a ratio when the capacity of the battery B is 100%.

From the above results, the battery of the present invention clearly has a large capacity of 5 mA / cm.²Discharge capacity / 1mA / cm²It can be seen that the discharge capacity is excellent.
Example-7
On the negative electrode a of Example-1, α-Al₂O_Three(Average particle size 1 μm) 93% by weight, scaly graphite 3% by weight, polyvinylidene fluoride 3% by weight, carboxymethylcellulose 1% by weight, mixed with water and kneaded into a slurry The produced electrode was designated as negative electrode d. In addition, a positive electrode having a thickness of 225 μm was obtained by reducing only the coating amount in the same manner as the positive electrode a of Example 1, and a positive electrode d having a protective layer similar to that of the positive electrode b was obtained.
A battery produced in the same manner as the battery B except that 120 mg of lithium metal per 1 g of the negative electrode material was applied in a strip shape on the negative electrode sheet c and the negative electrode sheet d of Example-5 and combined with the positive electrode sheet d. H. Ten pieces of each were produced, and the same test as in Example-6 was performed to obtain the following results. The discharge capacity in the table is shown as a ratio when the capacity of the battery G is 100%.

From the above results, the battery of the present invention clearly has a large capacity of 5 mA / cm.²Discharge capacity / 1mA / cm²It can be seen that the discharge capacity is excellent.
[0064]
  As in the present invention, lithium can be reversibly occluded and released.Transition metal oxideIncluding positive electrode,Includes metal oxides that can reversibly store and release lithiumIn a nonaqueous secondary battery comprising a negative electrode, a nonaqueous electrolyte containing a lithium salt, and a separator, the negative electrode and / or the positive electrode has at least one protective layer, and the protective layerNot conductiveSolid particles and conductive particlesSelected from cellulose derivatives, polyacrylic acid derivatives, polyvinyl alcohol derivatives, polyethylene oxide derivatives, and starchIt consists of a water-soluble polymer, and the thickness of the protective layer is1μm to 40μmTherefore, it is possible to stably produce a non-aqueous secondary battery having storage stability with a high discharge operating voltage and a large discharge capacity.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a cylindrical battery used in an example.
[Explanation of symbols]
8 Positive electrode sheet
9 Negative electrode sheet
10 Separator
11 Battery can
12 Battery cover
13 Gasket
14 Safety valve

Claims (12)

In a non-aqueous secondary battery comprising a positive electrode including a transition metal oxide capable of reversibly occluding and releasing lithium , a negative electrode including a metal oxide capable of reversibly occluding and releasing lithium, a non-aqueous electrolyte including a lithium salt, and a separator The negative electrode and / or the positive electrode have at least one protective layer, and the protective layer has non- conductive solid particles, conductive particles, cellulose derivatives, polyacrylic acid derivatives, polyvinyl alcohol derivatives, polyethylene oxide derivatives, and A non-aqueous secondary battery comprising a water-soluble polymer selected from starches , wherein the protective layer has a thickness of 1 μm or more and 40 μm or less . The nonaqueous secondary battery according to claim 1 , wherein the protective layer is formed on the negative electrode . The nonaqueous secondary battery according to claim 1 , wherein the protective layer is formed on the positive electrode . The non-aqueous secondary battery according to claim 1 , wherein the protective layer is formed on both the positive electrode and the negative electrode . The non-conductive solid particles contained in the protective layer are metals, carbides of nonmetallic elements, silicides, nitrides, sulfides, and oxides. Water secondary battery. The non-aqueous secondary battery according to claim 5 , wherein the non- conductive solid particles contained in the protective layer are inorganic chalcogenide particles . The non-aqueous secondary battery according to claim 6 , wherein the inorganic chalcogenide particles contain at least one oxide of sodium, potassium, magnesium, calcium, strontium, zirconium, aluminum, and silicon . The nonaqueous secondary battery according to claim 7, wherein the oxide according to claim 7 is alumina, silicon dioxide, or zirconia . The nonaqueous secondary battery according to claim 1 , wherein the water-soluble polymer contained in the protective layer is a polyacrylic acid derivative or a cellulose derivative . The nonaqueous secondary battery according to claim 9 , wherein the conductive particles contained in the protective layer are inorganic particles . The non-aqueous secondary battery according to claim 10, wherein the inorganic particles of claim 10 are metal powder, inorganic chalcogenide, or carbonaceous compound . The nonaqueous secondary battery according to claim 11, wherein the carbonaceous compound of claim 11 is natural graphite or vapor grown carbon .

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