JP5728515B2 - Method for producing positive electrode material for secondary battery - Google Patents
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- JP5728515B2 JP5728515B2 JP2013063834A JP2013063834A JP5728515B2 JP 5728515 B2 JP5728515 B2 JP 5728515B2 JP 2013063834 A JP2013063834 A JP 2013063834A JP 2013063834 A JP2013063834 A JP 2013063834A JP 5728515 B2 JP5728515 B2 JP 5728515B2
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- 239000007774 positive electrode material Substances 0.000 title claims description 35
- 238000004519 manufacturing process Methods 0.000 title claims description 24
- -1 silicate compound Chemical class 0.000 claims description 74
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 61
- 239000011246 composite particle Substances 0.000 claims description 31
- 239000011163 secondary particle Substances 0.000 claims description 27
- 239000011164 primary particle Substances 0.000 claims description 24
- 229910052723 transition metal Inorganic materials 0.000 claims description 24
- 238000010304 firing Methods 0.000 claims description 21
- 238000001027 hydrothermal synthesis Methods 0.000 claims description 18
- 239000002245 particle Substances 0.000 claims description 18
- 150000003624 transition metals Chemical class 0.000 claims description 17
- 238000001035 drying Methods 0.000 claims description 16
- 238000002156 mixing Methods 0.000 claims description 11
- 229910021389 graphene Inorganic materials 0.000 claims description 10
- 150000002642 lithium compounds Chemical class 0.000 claims description 10
- 238000000034 method Methods 0.000 claims description 10
- 229910052782 aluminium Inorganic materials 0.000 claims description 9
- 229910002804 graphite Inorganic materials 0.000 claims description 9
- 239000010439 graphite Substances 0.000 claims description 9
- 239000011541 reaction mixture Substances 0.000 claims description 8
- 229910052742 iron Inorganic materials 0.000 claims description 7
- 239000003273 ketjen black Substances 0.000 claims description 7
- 229910052759 nickel Inorganic materials 0.000 claims description 7
- 239000006230 acetylene black Substances 0.000 claims description 6
- 229910021393 carbon nanotube Inorganic materials 0.000 claims description 6
- 239000002041 carbon nanotube Substances 0.000 claims description 6
- 229910052720 vanadium Inorganic materials 0.000 claims description 6
- 229910052725 zinc Inorganic materials 0.000 claims description 6
- 229910052726 zirconium Inorganic materials 0.000 claims description 6
- 229910052748 manganese Inorganic materials 0.000 claims description 5
- WQZGKKKJIJFFOK-GASJEMHNSA-N Glucose Natural products OC[C@H]1OC(O)[C@H](O)[C@@H](O)[C@@H]1O WQZGKKKJIJFFOK-GASJEMHNSA-N 0.000 claims description 4
- 239000008103 glucose Substances 0.000 claims description 4
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- WQZGKKKJIJFFOK-VFUOTHLCSA-N beta-D-glucose Chemical compound OC[C@H]1O[C@@H](O)[C@H](O)[C@@H](O)[C@@H]1O WQZGKKKJIJFFOK-VFUOTHLCSA-N 0.000 claims description 2
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- WMFOQBRAJBCJND-UHFFFAOYSA-M Lithium hydroxide Chemical compound [Li+].[OH-] WMFOQBRAJBCJND-UHFFFAOYSA-M 0.000 description 13
- 229910052799 carbon Inorganic materials 0.000 description 13
- 239000010450 olivine Substances 0.000 description 12
- 229910052609 olivine Inorganic materials 0.000 description 12
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 11
- 239000000243 solution Substances 0.000 description 11
- 229910004283 SiO 4 Inorganic materials 0.000 description 10
- 229910000385 transition metal sulfate Inorganic materials 0.000 description 10
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 9
- 229910001416 lithium ion Inorganic materials 0.000 description 9
- 239000003963 antioxidant agent Substances 0.000 description 8
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- 239000000843 powder Substances 0.000 description 7
- 239000011734 sodium Substances 0.000 description 7
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- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 6
- 239000011230 binding agent Substances 0.000 description 6
- 239000011248 coating agent Substances 0.000 description 6
- 238000000576 coating method Methods 0.000 description 6
- 239000013078 crystal Substances 0.000 description 6
- 229910052744 lithium Inorganic materials 0.000 description 6
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 5
- 239000008151 electrolyte solution Substances 0.000 description 5
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- 150000003839 salts Chemical class 0.000 description 5
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- MUBZPKHOEPUJKR-UHFFFAOYSA-N Oxalic acid Chemical compound OC(=O)C(O)=O MUBZPKHOEPUJKR-UHFFFAOYSA-N 0.000 description 3
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 3
- QGZKDVFQNNGYKY-UHFFFAOYSA-N ammonia Natural products N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 3
- 125000004432 carbon atom Chemical group C* 0.000 description 3
- 239000003795 chemical substances by application Substances 0.000 description 3
- KRKNYBCHXYNGOX-UHFFFAOYSA-N citric acid Chemical compound OC(=O)CC(O)(C(O)=O)CC(O)=O KRKNYBCHXYNGOX-UHFFFAOYSA-N 0.000 description 3
- 239000002131 composite material Substances 0.000 description 3
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- 150000004760 silicates Chemical class 0.000 description 3
- 239000002904 solvent Substances 0.000 description 3
- 238000001694 spray drying Methods 0.000 description 3
- VZCYOOQTPOCHFL-OWOJBTEDSA-N Fumaric acid Chemical compound OC(=O)\C=C\C(O)=O VZCYOOQTPOCHFL-OWOJBTEDSA-N 0.000 description 2
- 229910010707 LiFePO 4 Inorganic materials 0.000 description 2
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 description 2
- 239000002033 PVDF binder Substances 0.000 description 2
- 239000004743 Polypropylene Substances 0.000 description 2
- MCMNRKCIXSYSNV-UHFFFAOYSA-N Zirconium dioxide Chemical compound O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 238000007600 charging Methods 0.000 description 2
- 239000002270 dispersing agent Substances 0.000 description 2
- 239000011267 electrode slurry Substances 0.000 description 2
- 239000010419 fine particle Substances 0.000 description 2
- 229910017053 inorganic salt Inorganic materials 0.000 description 2
- JVTAAEKCZFNVCJ-UHFFFAOYSA-N lactic acid Chemical compound CC(O)C(O)=O JVTAAEKCZFNVCJ-UHFFFAOYSA-N 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- XGZVUEUWXADBQD-UHFFFAOYSA-L lithium carbonate Chemical compound [Li+].[Li+].[O-]C([O-])=O XGZVUEUWXADBQD-UHFFFAOYSA-L 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 230000002093 peripheral effect Effects 0.000 description 2
- 229920001155 polypropylene Polymers 0.000 description 2
- 229920002981 polyvinylidene fluoride Polymers 0.000 description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- 235000012239 silicon dioxide Nutrition 0.000 description 2
- GEHJYWRUCIMESM-UHFFFAOYSA-L sodium sulfite Chemical compound [Na+].[Na+].[O-]S([O-])=O GEHJYWRUCIMESM-UHFFFAOYSA-L 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 239000002562 thickening agent Substances 0.000 description 2
- 229910021642 ultra pure water Inorganic materials 0.000 description 2
- 239000012498 ultrapure water Substances 0.000 description 2
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 description 1
- 229920002134 Carboxymethyl cellulose Polymers 0.000 description 1
- 229920002101 Chitin Polymers 0.000 description 1
- 229920001661 Chitosan Polymers 0.000 description 1
- KMTRUDSVKNLOMY-UHFFFAOYSA-N Ethylene carbonate Chemical compound O=C1OCCO1 KMTRUDSVKNLOMY-UHFFFAOYSA-N 0.000 description 1
- 102100031416 Gastric triacylglycerol lipase Human genes 0.000 description 1
- 101000941284 Homo sapiens Gastric triacylglycerol lipase Proteins 0.000 description 1
- 229910015015 LiAsF 6 Inorganic materials 0.000 description 1
- 229910013063 LiBF 4 Inorganic materials 0.000 description 1
- 229910013684 LiClO 4 Inorganic materials 0.000 description 1
- 229910012851 LiCoO 2 Inorganic materials 0.000 description 1
- 229910014689 LiMnO Inorganic materials 0.000 description 1
- 229910013385 LiN(SO2C2F5)2 Inorganic materials 0.000 description 1
- 229910013392 LiN(SO2CF3)(SO2C4F9) Inorganic materials 0.000 description 1
- 229910013870 LiPF 6 Inorganic materials 0.000 description 1
- 229910012424 LiSO 3 Inorganic materials 0.000 description 1
- 241000080590 Niso Species 0.000 description 1
- BPQQTUXANYXVAA-UHFFFAOYSA-N Orthosilicate Chemical compound [O-][Si]([O-])([O-])[O-] BPQQTUXANYXVAA-UHFFFAOYSA-N 0.000 description 1
- 241000282320 Panthera leo Species 0.000 description 1
- 239000004698 Polyethylene Substances 0.000 description 1
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- 229920002125 Sokalan® Polymers 0.000 description 1
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 1
- QSNQXZYQEIKDPU-UHFFFAOYSA-N [Li].[Fe] Chemical compound [Li].[Fe] QSNQXZYQEIKDPU-UHFFFAOYSA-N 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 229910021529 ammonia Inorganic materials 0.000 description 1
- 229910003481 amorphous carbon Inorganic materials 0.000 description 1
- 229910021383 artificial graphite Inorganic materials 0.000 description 1
- 150000001721 carbon Chemical group 0.000 description 1
- BVKZGUZCCUSVTD-UHFFFAOYSA-N carbonic acid Chemical class OC(O)=O BVKZGUZCCUSVTD-UHFFFAOYSA-N 0.000 description 1
- 150000004649 carbonic acid derivatives Chemical class 0.000 description 1
- 239000001768 carboxy methyl cellulose Substances 0.000 description 1
- 235000010948 carboxy methyl cellulose Nutrition 0.000 description 1
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- 239000002482 conductive additive Substances 0.000 description 1
- 239000006258 conductive agent Substances 0.000 description 1
- 238000010280 constant potential charging Methods 0.000 description 1
- 238000010277 constant-current charging Methods 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 150000001991 dicarboxylic acids Chemical class 0.000 description 1
- 235000014113 dietary fatty acids Nutrition 0.000 description 1
- QHGJSLXSVXVKHZ-UHFFFAOYSA-N dilithium;dioxido(dioxo)manganese Chemical compound [Li+].[Li+].[O-][Mn]([O-])(=O)=O QHGJSLXSVXVKHZ-UHFFFAOYSA-N 0.000 description 1
- 239000012153 distilled water Substances 0.000 description 1
- 230000002708 enhancing effect Effects 0.000 description 1
- 150000002170 ethers Chemical class 0.000 description 1
- JBTWLSYIZRCDFO-UHFFFAOYSA-N ethyl methyl carbonate Chemical compound CCOC(=O)OC JBTWLSYIZRCDFO-UHFFFAOYSA-N 0.000 description 1
- 239000000194 fatty acid Substances 0.000 description 1
- 229930195729 fatty acid Natural products 0.000 description 1
- 150000004665 fatty acids Chemical class 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 238000004108 freeze drying Methods 0.000 description 1
- 239000001530 fumaric acid Substances 0.000 description 1
- 238000005469 granulation Methods 0.000 description 1
- 230000003179 granulation Effects 0.000 description 1
- 150000008282 halocarbons Chemical class 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 239000011261 inert gas Substances 0.000 description 1
- 238000009830 intercalation Methods 0.000 description 1
- 238000005342 ion exchange Methods 0.000 description 1
- 150000002576 ketones Chemical class 0.000 description 1
- 239000004310 lactic acid Substances 0.000 description 1
- 235000014655 lactic acid Nutrition 0.000 description 1
- 150000002596 lactones Chemical class 0.000 description 1
- 229920005610 lignin Polymers 0.000 description 1
- XIXADJRWDQXREU-UHFFFAOYSA-M lithium acetate Chemical compound [Li+].CC([O-])=O XIXADJRWDQXREU-UHFFFAOYSA-M 0.000 description 1
- 229910052808 lithium carbonate Inorganic materials 0.000 description 1
- GELKBWJHTRAYNV-UHFFFAOYSA-K lithium iron phosphate Chemical compound [Li+].[Fe+2].[O-]P([O-])([O-])=O GELKBWJHTRAYNV-UHFFFAOYSA-K 0.000 description 1
- 229910021450 lithium metal oxide Inorganic materials 0.000 description 1
- 229910052912 lithium silicate Inorganic materials 0.000 description 1
- INHCSSUBVCNVSK-UHFFFAOYSA-L lithium sulfate Inorganic materials [Li+].[Li+].[O-]S([O-])(=O)=O INHCSSUBVCNVSK-UHFFFAOYSA-L 0.000 description 1
- 239000003595 mist Substances 0.000 description 1
- 239000012046 mixed solvent Substances 0.000 description 1
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- 239000007773 negative electrode material Substances 0.000 description 1
- 150000002825 nitriles Chemical class 0.000 description 1
- 239000011255 nonaqueous electrolyte Substances 0.000 description 1
- 235000005985 organic acids Nutrition 0.000 description 1
- 150000002894 organic compounds Chemical class 0.000 description 1
- 235000006408 oxalic acid Nutrition 0.000 description 1
- 238000010525 oxidative degradation reaction Methods 0.000 description 1
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- 229920000570 polyether Polymers 0.000 description 1
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- 229920000098 polyolefin Polymers 0.000 description 1
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- 238000004904 shortening Methods 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- JVBXVOWTABLYPX-UHFFFAOYSA-L sodium dithionite Chemical compound [Na+].[Na+].[O-]S(=O)S([O-])=O JVBXVOWTABLYPX-UHFFFAOYSA-L 0.000 description 1
- 235000010265 sodium sulphite Nutrition 0.000 description 1
- 238000010532 solid phase synthesis reaction Methods 0.000 description 1
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- RBTVSNLYYIMMKS-UHFFFAOYSA-N tert-butyl 3-aminoazetidine-1-carboxylate;hydrochloride Chemical compound Cl.CC(C)(C)OC(=O)N1CC(N)C1 RBTVSNLYYIMMKS-UHFFFAOYSA-N 0.000 description 1
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Classifications
-
- 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
Description
本発明は、優れた電池物性を有する二次電池を実現することのできる二次電池用正極材料を得るための製造方法に関する。 The present invention relates to a production method for obtaining a positive electrode material for a secondary battery capable of realizing a secondary battery having excellent battery properties.
リチウムイオン電池等の二次電池は、非水電解質電池の１種であり、携帯電話、デジタルカメラ、ノートＰＣ、ハイブリッド自動車、電気自動車等広い分野に利用されている。リチウムイオン電池は、正極材料としてリチウム金属酸化物を用い、負極材料としてグラファイト等の炭素材を用いるものが主流となっている。 A secondary battery such as a lithium ion battery is a kind of non-aqueous electrolyte battery, and is used in a wide range of fields such as a mobile phone, a digital camera, a notebook PC, a hybrid vehicle, and an electric vehicle. Lithium ion batteries mainly use lithium metal oxide as a positive electrode material and a carbon material such as graphite as a negative electrode material.
この正極材料としては、コバルト酸リチウム（ＬｉＣｏＯ2）、マンガン酸リチウム（ＬｉＭｎＯ2）、リン酸鉄リチウム（ＬｉＦｅＰＯ4）、ケイ酸鉄リチウム（Ｌｉ2ＦｅＳｉＯ4）等が知られている。このうち、ＬｉＦｅＰＯ4やＬｉ2ＦｅＳｉＯ4等は、オリビン構造を有し、高容量のリチウムイオン電池用正極材料として有用であり、特にＬｉ2ＦｅＳｉＯ4等のいわゆるオリビン型シリケート化合物は、優れた正極材料として注目を浴びている。 As this positive electrode material, lithium cobaltate (LiCoO 2 ), lithium manganate (LiMnO 2 ), lithium iron phosphate (LiFePO 4 ), lithium iron silicate (Li 2 FeSiO 4 ) and the like are known. Among these, LiFePO 4 and Li 2 FeSiO 4 have an olivine structure and are useful as positive electrode materials for high-capacity lithium ion batteries. In particular, so-called olivine-type silicate compounds such as Li 2 FeSiO 4 are excellent positive electrodes. It is attracting attention as a material.
これらオリビン型シリケート化合物を用いて二次電池を製造するには、かかるオリビン型シリケート化合物をバインダー溶液とともに混合して塗工液を調製し、得られた塗工液をアルミ箔等の正極集電体上に塗布した後、乾燥工程等を経ることにより正極を得る。この際、オリビン型シリケート化合物は、そのもの単独では導電性が低いため、二次電池の正極材料として用いるには、予めこれに導電性を付与する処理を施す。 In order to manufacture a secondary battery using these olivine-type silicate compounds, the olivine-type silicate compound is mixed with a binder solution to prepare a coating solution, and the resulting coating solution is used as a positive electrode current collector such as an aluminum foil. After coating on the body, a positive electrode is obtained through a drying process and the like. At this time, since the olivine silicate compound itself has low conductivity, in order to use it as a positive electrode material for a secondary battery, a treatment for imparting conductivity to the olivine type silicate compound is performed in advance.
オリビン型シリケート化合物に導電性を付与する処理としては、例えば、特許文献１には、オリビン型シリケート化合物のような正極材料表面に炭素源となる有機物を堆積させ、次いでジルコニアボールミル等の機械的処理や溶液を用いた処理を施した後、焼成する方法が開示されている。また、特許文献２には、特定のケイ酸リチウム化合物である固溶体化合物と炭素材料とを含む混合物を、不活性雰囲気下で３００〜５００℃にて熱処理をすることにより正極活物質を得る方法が開示されている。 As a treatment for imparting conductivity to the olivine-type silicate compound, for example, in Patent Document 1, an organic substance serving as a carbon source is deposited on the surface of a positive electrode material such as an olivine-type silicate compound, and then mechanical treatment such as zirconia ball mill is performed. And a method of firing after performing a treatment using a solution. Patent Document 2 discloses a method of obtaining a positive electrode active material by heat-treating a mixture containing a solid solution compound, which is a specific lithium silicate compound, and a carbon material at 300 to 500 ° C. in an inert atmosphere. It is disclosed.
しかしながら、上記特許文献１〜２では、ともに不活性雰囲気下で焼成を行うため、ガスの取り扱いの危険性に配慮する必要があり、また特定の焼成装置に限られるという制限がある。さらに、上記特許文献２に記載のように、不活性雰囲気下で３００〜５００℃の温度域にて熱処理を施すと、正極材料であるオリビン型シリケート化合物の温度による粒成長がおこり、得られる電池において充放電容量の低下を招くこととなる。 However, in the above-mentioned Patent Documents 1 and 2, since firing is performed in an inert atmosphere, it is necessary to consider the danger of gas handling, and there is a limitation that it is limited to a specific firing apparatus. Furthermore, as described in Patent Document 2, when heat treatment is performed in a temperature range of 300 to 500 ° C. in an inert atmosphere, grain growth occurs due to the temperature of the olivine-type silicate compound that is the positive electrode material, and the resulting battery In this case, the charge / discharge capacity is reduced.
したがって、本発明の課題は、オリビン型シリケート化合物を用いつつ、優れた導電性を有するとともに、電池性能をも十分に高めることのできる正極材料を得るための方法を提供することにある。 Accordingly, an object of the present invention is to provide a method for obtaining a positive electrode material having excellent conductivity and sufficiently improving battery performance while using an olivine type silicate compound.
そこで本発明者らは、オリビン型シリケート化合物を含有する二次電池用正極材料を製造するにあたり、水熱反応により得られたオリビン型シリケート化合物の一次粒子を用いて得られた二次粒子を導電性炭素粉末とともに特定の条件下で混合して複合粒子を形成した後、大気雰囲気下にて特定の温度域で焼成することによって、電池性能を飛躍的に高めることのできる二次電池用正極材料が得られることを見出し、本発明を完成させるに至った。 Accordingly, the inventors of the present invention, when producing a positive electrode material for a secondary battery containing an olivine-type silicate compound, electrically conducts secondary particles obtained using primary particles of an olivine-type silicate compound obtained by a hydrothermal reaction. A positive electrode material for a secondary battery that can dramatically improve battery performance by forming composite particles with specific carbon powder under specific conditions and then firing in a specific temperature range in an air atmosphere Has been found, and the present invention has been completed.
すなわち、本発明は、水熱反応により得られたオリビン型シリケート化合物の一次粒子を乾燥して二次粒子を形成し、
得られた二次粒子及び導電性炭素粉末を乾式下にて圧縮力及びせん断力を付加しながら混合することにより、複合粒子を形成し、
次いで、得られた複合粒子を大気雰囲気下にて２００〜３００℃で焼成することを特徴とする、二次電池用正極材料の製造方法を提供するものである。
また、本発明は、上記製造方法により得られた二次電池用正極材料、及びかかる二次電池用正極材料を含む正極を有する二次電池を提供するものである。
That is, the present invention forms primary particles by drying primary particles of the olivine-type silicate compound obtained by the hydrothermal reaction,
By mixing the obtained secondary particles and conductive carbon powder while applying compressive force and shear force under a dry process, composite particles are formed,
Then, the obtained composite particles are fired at 200 to 300 ° C. in an air atmosphere, and a method for producing a positive electrode material for a secondary battery is provided.
Moreover, this invention provides the secondary battery which has a positive electrode material containing the positive electrode material for secondary batteries obtained by the said manufacturing method, and this positive electrode material for secondary batteries.
本発明の製造方法によれば、製造過程で生じたオリビン型シリケート化合物の結晶構造の歪みを復元して結晶配向性を高めることができるとともに、粒成長を効果的に抑制することも可能となるため、得られる二次電池用正極材料は優れた導電性及び高い充放電容量を有しており、二次電池用の正極材料として非常に有用である。 According to the production method of the present invention, the crystal orientation of the olivine-type silicate compound generated in the production process can be restored to improve the crystal orientation, and the grain growth can be effectively suppressed. Therefore, the obtained positive electrode material for a secondary battery has excellent conductivity and high charge / discharge capacity, and is very useful as a positive electrode material for a secondary battery.
以下、本発明について詳細に説明する。
本発明の製造方法では、まず水熱反応によりオリビン型シリケート化合物の一次粒子を得る。
オリビン型シリケート化合物としては、遷移金属Ｍ（Ｍは、Ｆｅ、Ｎｉ、Ｃｏ、Ａｌ、Ｚｎ、Ｖ、Ｚｒ又はＭｎを示す）を含むのが好ましい。かかる遷移金属Ｍを含むオリビン型シリケート化合物は、具体的には下記式（１）〜（５）のいずれかで表わされる。
Ｌｉ2Ｍ'ＳｉＯ4 ・・・（１）
（式中、Ｍ'はＦｅ、Ｎｉ、Ｃｏ及びＭｎから選ばれる１種又は２種以上を示す。）
Ｌｉa'ＦｅxＭｎyＡｌzＳｉＯ4 ・・・（２）
（式中、ａ'、ｘ、ｙ及びｚは、１＜ａ'≦２、０≦ｘ＜１、０≦ｙ＜１、０＜ｚ＜２／３、ａ'＋２ｘ＋２ｙ＋３ｚ＝４、及びｘ＋ｙ≠０を満たす数を示す。）
Ｌｉa"ＦｅxＭｎyＶz'ＳｉＯ4 ・・・（３）
（式中、ａ"、ｘ、ｙ及びｚ'は、１＜ａ"≦２、０≦ｘ＜１、０≦ｙ＜１、０＜ｚ'＜１、ａ"＋２ｘ＋２ｙ＋（２〜５）ｚ'＝４、及びｘ＋ｙ≠０を満たす数を示す。）
Ｌｉa"ＦｅxＭｎyＺｒz"ＳｉＯ4 ・・・（４）
（式中、ａ"、ｘ、ｙ及びｚ"は、１＜ａ"≦２、０≦ｘ＜１、０≦ｙ＜１、０＜ｚ"＜０．５、ａ"＋２ｘ＋２ｙ＋４ｚ"＝４、及びｘ＋ｙ≠０を満たす数を示す。）
Ｌｉ2ＦｅxＭｎyＺｎqＳｉＯ4 ・・・（５）
（式中、ｘ、ｙ及びｑは、０≦ｘ＜１、０≦ｙ＜１、０＜ｑ＜１、ｘ＋ｙ＋ｑ＝１、及びｘ＋ｙ≠０を満たす数を示す。）
Hereinafter, the present invention will be described in detail.
In the production method of the present invention, primary particles of an olivine-type silicate compound are first obtained by a hydrothermal reaction.
The olivine-type silicate compound preferably contains a transition metal M (M represents Fe, Ni, Co, Al, Zn, V, Zr or Mn). The olivine-type silicate compound containing such a transition metal M is specifically represented by any of the following formulas (1) to (5).
Li 2 M'SiO 4 (1)
(In the formula, M ′ represents one or more selected from Fe, Ni, Co and Mn.)
Li a 'Fe x Mn y Al z SiO 4 ··· (2)
(Where, a ′, x, y and z are 1 <a ′ ≦ 2, 0 ≦ x <1, 0 ≦ y <1, 0 <z <2/3, a ′ + 2x + 2y + 3z = 4, and x + y ≠ Indicates a number satisfying 0.)
Li a "Fe x Mn y V z 'SiO 4 ··· (3)
(Where a " , x, y and z 'are 1 <a " ≤2, 0≤x <1, 0≤y <1, 0 <z'<1, a " + 2x + 2y + (2-5) z '= 4 and a number satisfying x + y ≠ 0.)
Li a "Fe x Mn y Zr z" SiO 4 ··· (4)
(Where a " , x, y and z " are 1 <a " ≤2, 0≤x <1, 0≤y <1, 0 <z " <0.5, a " + 2x + 2y + 4z " = 4, And a number satisfying x + y ≠ 0.)
Li 2 Fe x Mn y Zn q SiO 4 ··· (5)
(In the formula, x, y, and q represent numbers satisfying 0 ≦ x <1, 0 ≦ y <1, 0 <q <1, x + y + q = 1, and x + y ≠ 0.)
上記オリビン型シリケート化合物は、例えば、遷移金属（Ｍ）源として、ＭＳＯ4（式中、Ｍは、Ｆｅ、Ｎｉ、Ｃｏ、Ａｌ、Ｚｎ、Ｖ、Ｚｒ又はＭｎを示す）で表される遷移金属硫酸塩又は（Ｒ）2Ｍ（式中、Ｒは有機酸残基を示し、Ｍは、Ｆｅ、Ｎｉ、Ｃｏ、Ａｌ、Ｚｎ、Ｖ、Ｚｒ又はＭｎを示す）で表される有機酸遷移金属塩を用い、リチウム化合物及びケイ酸化合物、必要に応じ酸化防止剤を含有する塩基性水分散液を水熱反応させることにより製造することができる。 The olivine-type silicate compound is, for example, a transition metal represented by MSO 4 (wherein M represents Fe, Ni, Co, Al, Zn, V, Zr, or Mn) as a transition metal (M) source. Organic acid transition metal represented by sulfate or (R) 2 M (wherein R represents an organic acid residue, M represents Fe, Ni, Co, Al, Zn, V, Zr or Mn) It can be produced by hydrothermal reaction of a basic aqueous dispersion containing a lithium compound, a silicate compound and, if necessary, an antioxidant, using a salt.
リチウム化合物としては、水酸化リチウム（例えばＬｉＯＨ・Ｈ2Ｏ）、炭酸リチウム（Ｌｉ2ＣＯ3）、硫酸リチウム、酢酸リチウムが挙げられるが、水酸化リチウム、炭酸リチウムが特に好ましい。遷移金属（Ｍ）源として遷移金属硫酸塩（ＭＳＯ4）を用いる場合における、塩基性水分散液中のリチウム化合物の濃度は、オリビン型シリケート化合物の二次粒子を適切な平均粒径に制御しつつ、これと導電性炭素粉末とを混合した際に、これらが堅固に凝集した複合粒子を得る観点から、０．３０〜３．００ｍｏｌ／ｌが好ましく、１．００〜２．８０ｍｏｌ／ｌがより好ましく、１．５０〜２．８０ｍｏｌ／ｌがさらに好ましい。 Examples of the lithium compound include lithium hydroxide (for example, LiOH.H 2 O), lithium carbonate (Li 2 CO 3 ), lithium sulfate, and lithium acetate, and lithium hydroxide and lithium carbonate are particularly preferable. When transition metal sulfate (MSO 4 ) is used as the transition metal (M) source, the concentration of the lithium compound in the basic aqueous dispersion is controlled so that the secondary particles of the olivine-type silicate compound have an appropriate average particle size. On the other hand, when this and the conductive carbon powder are mixed, 0.30 to 3.00 mol / l is preferable, and 1.00 to 2.80 mol / l is preferable from the viewpoint of obtaining composite particles in which these are firmly aggregated. More preferred is 1.50 to 2.80 mol / l.
ケイ酸化合物としては、反応性のあるシリカ化合物であれば特に限定されず、非晶質シリカ、Ｎａ4ＳｉＯ4（例えばＮａ4ＳｉＯ4・Ｈ2Ｏ）が好ましい。このうちＮａ4ＳｉＯ4を用いた場合、水分散液が塩基性になるので、より好ましい。遷移金属（Ｍ）源として遷移金属硫酸塩（ＭＳＯ4）を用いる場合における、塩基性水分散液中のケイ酸化合物の濃度は、オリビン型シリケート化合物の二次粒子を適切な平均粒径に制御しつつ、これと導電性炭素粉末とを混合した際に、これらが堅固に凝集した複合粒子を得る観点から、０．１５〜１.５０ｍｏｌ／ｌが好ましく、０．５０〜１．４０ｍｏｌ／ｌがより好ましく、０．８０〜１．４０ｍｏｌ／ｌがさらに好ましい。 The silicic acid compound is not particularly limited as long as it is a reactive silica compound, and amorphous silica and Na 4 SiO 4 (for example, Na 4 SiO 4 .H 2 O) are preferable. Of these, the use of Na 4 SiO 4 is more preferable because the aqueous dispersion becomes basic. When using transition metal sulfate (MSO 4 ) as the transition metal (M) source, the concentration of the silicate compound in the basic aqueous dispersion is controlled to a suitable average particle size of the secondary particles of the olivine-type silicate compound. However, from the viewpoint of obtaining composite particles in which they are firmly aggregated when mixed with the conductive carbon powder, 0.15 to 1.50 mol / l is preferable, and 0.50 to 1.40 mol / l. Is more preferable, and 0.80 to 1.40 mol / l is more preferable.
さらにこの塩基性水分散液には、副反応を防止する観点から、酸化防止剤を添加することが好ましい。酸化防止剤としては、ハイドロサルファイトナトリウム（Ｎａ2Ｓ2Ｏ4）、アンモニア水、亜硫酸ナトリウム等を使用することができる。遷移金属（Ｍ）源として遷移金属硫酸塩（ＭＳＯ4）を用いる場合における、塩基性水分散液中の酸化防止剤の含有量は、多量に添加するとオリビン型シリケート化合物の生成を抑制してしまうため、遷移金属（Ｍ）に対して等モル量以下が好ましく、遷移金属（Ｍ）に対してモル比で０．５以下がさらに好ましい。 Furthermore, it is preferable to add an antioxidant to the basic aqueous dispersion from the viewpoint of preventing side reactions. As the antioxidant, hydrosulfite sodium (Na 2 S 2 O 4 ), aqueous ammonia, sodium sulfite and the like can be used. In the case of using transition metal sulfate (MSO 4 ) as a transition metal (M) source, the content of the antioxidant in the basic aqueous dispersion suppresses the generation of an olivine silicate compound when added in a large amount. Therefore, an equimolar amount or less is preferable with respect to the transition metal (M), and a molar ratio with respect to the transition metal (M) is more preferably 0.5 or less.
遷移金属源として遷移金属硫酸塩ＭＳＯ4（式中、Ｍは、Ｆｅ、Ｎｉ、Ｃｏ、Ａｌ、Ｚｎ、Ｖ、Ｚｒ又はＭｎを示す）を用いる場合、副反応を抑制する点から、遷移金属硫酸塩とは別に、リチウム化合物及びケイ酸化合物を含有する塩基性水分散液を予め調製しておくのが好ましい。この場合、該塩基性水分散液と遷移金属硫酸塩及び酸化防止剤とを混合し、水熱反応に付す。該塩基性水分散液の調製にあたって、リチウム化合物及びケイ酸化合物の添加順序は特に限定されず、これらの２成分を同時に水に添加してもよい。 When transition metal sulfate MSO 4 (wherein M represents Fe, Ni, Co, Al, Zn, V, Zr or Mn) is used as the transition metal source, transition metal sulfate from the viewpoint of suppressing side reactions. Apart from the salt, a basic aqueous dispersion containing a lithium compound and a silicate compound is preferably prepared in advance. In this case, the basic aqueous dispersion, the transition metal sulfate and the antioxidant are mixed and subjected to a hydrothermal reaction. In the preparation of the basic aqueous dispersion, the order of addition of the lithium compound and the silicate compound is not particularly limited, and these two components may be simultaneously added to water.
遷移金属硫酸塩ＭＳＯ4の具体例としては、ＦｅＳＯ4、ＮｉＳＯ4、ＣｏＳＯ4、Ａｌ2（ＳＯ4）3、ＺｎＳＯ4、Ｖ2（ＳＯ4）3、Ｚｒ（ＳＯ4）2又はＭｎＳＯ4が挙げられ、これらは１種単独で用いてもよく２種以上を混合して用いてもよい。これらのうち、ＦｅＳＯ4、ＭｎＳＯ4がより好ましく、ＦｅＳＯ4がさらに好ましい。遷移金属硫酸塩（ＭＳＯ4）の添加量は、得られるオリビン型シリケート化合物と導電性炭素粉末とを混合した際に、これらが堅固に凝集した複合粒子とする観点から、上記塩基性水分散液及び遷移金属硫酸塩の双方を含む反応混合液全量中に、０．１５〜１.５０ｍｏｌ／ｌとなる量が好ましく、０．５０〜１．４０ｍｏｌ／ｌとなる量がより好ましく、０．８０〜１．４０ｍｏｌ／ｌとなる量がさらに好ましい。
なお、この場合における反応混合液中のＬｉの含有量は、Ｍに対して２モル以上が好ましい。
Specific examples of the transition metal sulfate MSO 4 include FeSO 4 , NiSO 4 , CoSO 4 , Al 2 (SO 4 ) 3 , ZnSO 4 , V 2 (SO 4 ) 3 , Zr (SO 4 ) 2 or MnSO 4. These may be used singly or in combination of two or more. Of these, FeSO 4 and MnSO 4 are more preferable, and FeSO 4 is more preferable. The amount of transition metal sulfate (MSO 4 ) added is the above basic aqueous dispersion from the viewpoint of forming composite particles in which the obtained olivine-type silicate compound and conductive carbon powder are firmly aggregated when mixed. And the total amount of the reaction mixture containing both transition metal sulfates is preferably 0.15 to 1.50 mol / l, more preferably 0.50 to 1.40 mol / l, more preferably 0.80. An amount of ˜1.40 mol / l is more preferred.
In this case, the Li content in the reaction mixture is preferably 2 mol or more with respect to M.
遷移金属源として有機酸遷移金属塩（Ｒ）2Ｍ（式中、Ｒは有機酸残基を示し、Ｍは、Ｆｅ、Ｎｉ、Ｃｏ、Ａｌ、Ｚｎ、Ｖ、Ｚｒ又はＭｎを示す）を用いる場合には、リチウム化合物、ケイ酸化合物及び酸化防止剤を含有し、さらに有機酸遷移金属塩を含有する塩基性水分散液を調製する。この場合、リチウム化合物、ケイ酸化合物、酸化防止剤及び有機酸遷移金属塩の添加順序は特に限定されない。また、大気条件下でもよい。遷移金属源として有機酸遷移金属塩（Ｒ）2Ｍを用いる場合における、塩基性水分散液中（反応混合液全量中）のリチウム化合物の濃度は、オリビン型シリケート化合物の二次粒子を適切な平均粒径に制御しつつ、これと導電性炭素粉末とを混合した際に、これらが堅固に凝集した複合粒子を得る観点から、０．３０〜３．００ｍｏｌ／ｌが好ましく、１．００〜２．８０ｍｏｌ／ｌがより好ましく、１．５０〜２．８０ｍｏｌ/ｌがさらに好ましい。また、塩基性水分散液中（反応混合液全量中）のケイ酸化合物の含有量は、同様の観点から、０．１５〜１.５０ｍｏｌ／ｌが好ましく、０．５０〜１．４０ｍｏｌ／ｌがより好ましく、０．８０〜１．４０ｍｏｌ／ｌがさらに好ましい。さらに、塩基性水分散液中（反応混合液全量中）の酸化防止剤の濃度は、多量に添加するとオリビン型シリケート化合物の生成を抑制してしまうため、遷移金属（Ｍ）に対して等モル量以下が好ましく、遷移金属（Ｍ）に対してモル比で０．５以下がさらに好ましい。通常、有機酸塩は固相法に用いられる原料であるが、水熱反応に用いることにより副反応を抑制することができる。
なお、この場合における反応混合液中のＬｉは、遷移金属に対してモル比で２倍以上用いることが好ましく、Ｌｉ：Ｍが２．５：１〜３：１程度がより好ましい。
An organic acid transition metal salt (R) 2 M (wherein R represents an organic acid residue, and M represents Fe, Ni, Co, Al, Zn, V, Zr, or Mn) is used as a transition metal source. In some cases, a basic aqueous dispersion containing a lithium compound, a silicate compound and an antioxidant and further containing an organic acid transition metal salt is prepared. In this case, the order of addition of the lithium compound, silicic acid compound, antioxidant and organic acid transition metal salt is not particularly limited. Moreover, atmospheric conditions may be sufficient. When the organic acid transition metal salt (R) 2 M is used as the transition metal source, the concentration of the lithium compound in the basic aqueous dispersion (in the total amount of the reaction mixture) is determined appropriately by the secondary particles of the olivine silicate compound. From the viewpoint of obtaining composite particles in which these are firmly aggregated when mixed with conductive carbon powder while controlling the average particle diameter, 0.30 to 3.00 mol / l is preferable, and 1.00 to 2.80 mol / l is more preferable, and 1.50 to 2.80 mol / l is more preferable. Further, the content of the silicate compound in the basic aqueous dispersion (in the total amount of the reaction mixture) is preferably 0.15 to 1.50 mol / l, and preferably 0.50 to 1.40 mol / l from the same viewpoint. Is more preferable, and 0.80 to 1.40 mol / l is more preferable. Furthermore, since the concentration of the antioxidant in the basic aqueous dispersion (in the total amount of the reaction mixture) suppresses the formation of the olivine-type silicate compound when added in a large amount, it is equimolar to the transition metal (M). The amount is preferably at most 0.5, and more preferably at most 0.5 in terms of molar ratio to the transition metal (M). Usually, an organic acid salt is a raw material used in a solid phase method, but side reactions can be suppressed by using it in a hydrothermal reaction.
In this case, Li in the reaction mixture is preferably used in a molar ratio of 2 times or more with respect to the transition metal, and Li: M is more preferably about 2.5: 1 to 3: 1.
有機酸遷移金属塩（Ｒ）2ＭのＲで示される有機酸としては、炭素数１〜２０の有機酸が好ましく、炭素数２〜１２の有機酸がより好ましい。より具体的な有機酸としては、シュウ酸、フマル酸等のジカルボン酸、乳酸等のヒドロキシカルボン酸、酢酸等の脂肪酸が挙げられる。塩基性水分散液中（反応混合液全量中）の有機酸遷移金属塩（Ｒ）2Ｍの濃度は、得られるオリビン型シリケート化合物と導電性炭素粉末とを混合した際に、これらが堅固に凝集した複合粒子とする観点から、０．１５〜１．５０ｍｏｌ／ｌが好ましく、０．５〜１．４０ｍｏｌ／ｌがより好ましく、０．８０〜１．４０ｍｏｌ／ｌがさらに好ましい。 The organic acid represented by an organic acid transition metal salt (R) of 2 M R, preferably an organic acid having 1 to 20 carbon atoms, more preferably an organic acid having 2 to 12 carbon atoms. More specific organic acids include dicarboxylic acids such as oxalic acid and fumaric acid, hydroxycarboxylic acids such as lactic acid, and fatty acids such as acetic acid. The concentration of the organic acid transition metal salt (R) 2 M in the basic aqueous dispersion (in the total amount of the reaction mixture) is such that when the obtained olivine-type silicate compound and the conductive carbon powder are mixed, they are firmly From the viewpoint of forming aggregated composite particles, 0.15 to 1.50 mol / l is preferable, 0.5 to 1.40 mol / l is more preferable, and 0.80 to 1.40 mol / l is even more preferable.
該水分散液は塩基性とするのが、副反応を防止し、ケイ酸化合物を溶解するうえで重要である。具体的には、該塩基性水分散液のｐＨが１２．０〜１３．５であるのが副反応（Ｆｅ3Ｏ4の生成）の防止、ケイ酸化合物の溶解性及び反応の進行の点で特に好ましい。該塩基性水分散液のｐＨの調整は、塩基、例えば、水酸化ナトリウムを添加することにより行ってもよいが、ケイ酸化合物としてＮａ4ＳｉＯ4を用いるのが特に好ましい。 Making the aqueous dispersion basic is important in preventing side reactions and dissolving the silicate compound. Specifically, the pH of the basic aqueous dispersion is 12.0 to 13.5 to prevent side reactions (formation of Fe 3 O 4 ), solubility of silicate compounds, and progress of the reaction. Is particularly preferable. The pH of the basic aqueous dispersion may be adjusted by adding a base such as sodium hydroxide, but it is particularly preferable to use Na 4 SiO 4 as the silicate compound.
水熱反応は、１００℃以上であればよく、１３０〜２００℃が好ましく、さらに１４０〜１８０℃が好ましい。水熱反応は耐圧容器中で行うのが好ましく、１３０〜２００℃で反応を行う場合の圧力は０．３〜１．５ＭＰａとなり、１４０〜１８０℃で反応を行う場合の圧力は０．４〜１．０ＭＰａとなる。水熱反応時間は１〜２４時間が好ましく、さらに３〜１２時間が好ましい。 Hydrothermal reaction should just be 100 degreeC or more, 130-200 degreeC is preferable and 140-180 degreeC is more preferable. The hydrothermal reaction is preferably carried out in a pressure vessel, the pressure when the reaction is carried out at 130 to 200 ° C. is 0.3 to 1.5 MPa, and the pressure when the reaction is carried out at 140 to 180 ° C. is 0.4 to 1.0 MPa. The hydrothermal reaction time is preferably 1 to 24 hours, more preferably 3 to 12 hours.
当該水熱反応により、オリビン型シリケート化合物の一次粒子が高収率で得られ、その結晶度も高い。一次粒子の平均粒径は、二次電池の電池物性を高める観点から、好ましくは１０〜５００ｎｍであり、より好ましくは１０〜１００ｎｍである。 By the hydrothermal reaction, primary particles of the olivine-type silicate compound are obtained in a high yield, and the crystallinity is high. The average particle diameter of the primary particles is preferably 10 to 500 nm, more preferably 10 to 100 nm, from the viewpoint of improving the battery physical properties of the secondary battery.
得られたオリビン型シリケート化合物の一次粒子は、洗浄後にろ過し、次いで乾燥することにより二次粒子として単離することができる。乾燥手段としては、噴霧乾燥、箱型乾燥、流動床乾燥、外熱式乾燥、凍結乾燥、真空乾燥が挙げられる。なかでも、スプレードライヤーを用いた噴霧乾燥が好ましい。また、乾燥する際、予めオリビン型シリケート化合物の一次粒子を用いて調製したスラリーを用いるのがよい。かかるスラリーにおけるオリビン型シリケート化合物の一次粒子の含有量（固形分濃度）は、好適な平均粒径を有する二次粒子を得る観点から、好ましくは２０〜６０質量％であり、より好ましくは３０〜５０質量％であり、さらに好ましくは３５〜４５質量％である。 The primary particles of the obtained olivine type silicate compound can be isolated as secondary particles by filtering after washing and then drying. Examples of the drying means include spray drying, box drying, fluidized bed drying, external heat drying, freeze drying, and vacuum drying. Of these, spray drying using a spray dryer is preferred. Moreover, when drying, it is good to use the slurry previously prepared using the primary particle of the olivine type silicate compound. From the viewpoint of obtaining secondary particles having a suitable average particle size, the content (solid content concentration) of primary particles of the olivine-type silicate compound in the slurry is preferably 20 to 60% by mass, more preferably 30 to 30%. It is 50 mass%, More preferably, it is 35-45 mass%.
この際、分散剤や増粘剤をスラリーに少量添加しても良く、分散剤としては、例えば、ポリカルボン酸系、ポリエーテル系、ポリアクリル酸系などを用いることができる。
増粘剤としては、例えば、水酸化ナトリウム、水酸化リチウム、アンモニアなどの塩基や酢酸、クエン酸などの有機酸を用いることができる。
At this time, a small amount of a dispersant or a thickener may be added to the slurry, and as the dispersant, for example, a polycarboxylic acid type, a polyether type, a polyacrylic acid type, or the like can be used.
As the thickener, for example, a base such as sodium hydroxide, lithium hydroxide or ammonia, or an organic acid such as acetic acid or citric acid can be used.
こうして得られる乾燥物については、乾燥時又は乾燥後にセパレータ、サイクロン、篩等で分級してもよく、また乳鉢ピンミル、ロールミル、クラッシャー等を用いて粉砕してもよい。 The dried product thus obtained may be classified with a separator, cyclone, sieve or the like during or after drying, or may be pulverized with a mortar pin mill, roll mill, crusher or the like.
得られた二次粒子の平均粒径は、後に導電性炭素粉末とともに混合した際に、これらが堅固に凝集した複合粒子とする観点から、好ましくは３〜１５０μｍであり、より好ましくは３〜１００μｍであり、さらに好ましくは５〜５０μｍである。 The average particle diameter of the obtained secondary particles is preferably 3 to 150 μm, more preferably 3 to 100 μm, from the viewpoint of forming composite particles in which these particles are firmly aggregated when mixed with the conductive carbon powder later. More preferably, it is 5-50 micrometers.
かかる二次粒子及び導電性炭素粉末を乾式下にて圧縮力及びせん断力を付加しながら混合することにより、複合粒子を形成する。このような混合工程を経ることにより、かかる導電性炭素が、一次粒子又は／及び二次粒子と一次粒子又は／及び二次粒子との間隙に効率的に配置された複合体となり、続いて大気雰囲気下にて２００〜３００℃で焼成することにより、高嵩密度で結晶配向性の高い複合粒子を得ることができる。 The secondary particles and the conductive carbon powder are mixed while applying a compressive force and a shearing force under a dry method to form composite particles. Through such a mixing step, the conductive carbon becomes a composite that is efficiently arranged in the gap between the primary particles or / and the secondary particles and the primary particles or / and the secondary particles, and then the atmosphere. By firing at 200 to 300 ° C. in an atmosphere, composite particles having a high bulk density and high crystal orientation can be obtained.
用いることのできる導電性炭素粉末としては、ケッチェンブラック、アセチレンブラック、黒鉛、グラフェン、グラフェンオキサイド、カーボンナノチューブ、グルコース、デンプンが挙げられる。これらは１種単独で用いてもよく、２種以上組み合わせて用いてもよい。なかでも、オリビンシリケート化合物の電子伝導面積（電子伝導パス）を増加させて二次電池の電池物性を高める観点から、ケッチェンブラック、アセチレンブラック、黒鉛、グラフェン、グラフェンオキサイド、カーボンナノチューブが好ましく、ケッチェンブラックがより好ましい。 Examples of the conductive carbon powder that can be used include ketjen black, acetylene black, graphite, graphene, graphene oxide, carbon nanotube, glucose, and starch. These may be used alone or in combination of two or more. Of these, ketjen black, acetylene black, graphite, graphene, graphene oxide, and carbon nanotube are preferred from the viewpoint of increasing the electron conduction area (electron conduction path) of the olivine silicate compound and improving the battery physical properties of the secondary battery. Chain black is more preferred.
乾式下にて圧縮力及びせん断力を付加しながら混合するのに用いる装置としては、インペラを備える密閉容器を用いるのが好ましく、ここにオリビン型シリケート化合物の二次粒子及び導電性炭素を投入すればよい。かかる容器においてインペラが回転することより、投入されたオリビン型シリケート化合物及び導電性炭素を均一に混合するとともに、インペラと容器内壁との間で圧縮力を付加しながらせん断力も付加することができる。インペラが回転するにあたり、その周速は、オリビン型シリケート化合物の二次粒子と二次粒子の間に導電性炭素が混入し、これらが均一に分散したまま堅固に凝集して複合粒子を形成する観点から、好ましくは２５〜７０ｍ／ｓであり、より好ましくは２７〜５５ｍ／ｓであり、回転数としては、好ましくは４０００〜９０００ｒｐｍである。また、処理時間は、好ましくは１５〜６０分であり、より好ましくは２０〜４０分である。 As an apparatus used for mixing while applying compressive force and shear force under dry conditions, it is preferable to use an airtight container equipped with an impeller, where secondary particles of olivine-type silicate compound and conductive carbon are added. That's fine. By rotating the impeller in such a container, the charged olivine-type silicate compound and conductive carbon can be mixed uniformly, and a shearing force can be applied while applying a compressive force between the impeller and the inner wall of the container. When the impeller rotates, the peripheral speed is such that conductive carbon is mixed between the secondary particles of the olivine-type silicate compound and the secondary particles are uniformly dispersed to form composite particles. From the viewpoint, it is preferably 25 to 70 m / s, more preferably 27 to 55 m / s, and the rotation speed is preferably 4000 to 9000 rpm. Moreover, processing time becomes like this. Preferably it is 15-60 minutes, More preferably, it is 20-40 minutes.
なお、得られる複合粒子の均一性を高める観点、及びインペラを備える密閉容器内での処理時間を短縮化する観点から、かかる密閉容器内へオリビン型シリケート化合物及び導電性炭素を投入する前に、予めこれらを混合してもよい。 In addition, from the viewpoint of increasing the uniformity of the obtained composite particles, and from the viewpoint of shortening the processing time in a closed container equipped with an impeller, before introducing the olivine-type silicate compound and conductive carbon into such a closed container, These may be mixed in advance.
このような圧縮力及びせん断力を付加しながら混合することのできる密閉容器を備える装置としては、具体的には、高速せん断ミル、ブレード型混練機等が挙げられ、より具体的には、例えば、微粒子複合化装置 ノビルタ（ホソカワミクロン社製）を好適に用いることができる。かかる装置を用いることにより、容易に所定の圧縮力とせん断力を付加しながらの混合処理を行うことができ、次いで後述する大気雰囲気下における特定温度での焼成の工程を経ることにより、結晶構造の歪みを有効に除去しつつ粒成長を効果的に抑制し、二次電池の電池物性を高めることが可能な正極材料を得ることができる。 Specific examples of the apparatus including a closed container that can be mixed while applying such compressive force and shear force include a high-speed shear mill, a blade-type kneader, and the like. In addition, a fine particle composite apparatus Nobilta (manufactured by Hosokawa Micron) can be suitably used. By using such an apparatus, it is possible to easily carry out a mixing process while applying a predetermined compressive force and shearing force, and then, through a step of firing at a specific temperature in an air atmosphere described later, a crystal structure Thus, it is possible to obtain a positive electrode material capable of effectively suppressing grain growth and effectively improving battery physical properties of the secondary battery while effectively removing the distortion.
上記混合の処理条件としては、処理温度が、好ましくは５〜８０℃、より好ましくは１０〜５０℃であり、処理時間が、好ましくは５〜９０分、より好ましくは１０〜６０分である。処理雰囲気としては、特に限定されないが、不活性ガス雰囲気下、または還元ガス雰囲気下でもよい。 As the processing conditions for the mixing, the processing temperature is preferably 5 to 80 ° C., more preferably 10 to 50 ° C., and the processing time is preferably 5 to 90 minutes, more preferably 10 to 60 minutes. The treatment atmosphere is not particularly limited, but may be an inert gas atmosphere or a reducing gas atmosphere.
上記密閉容器内に投入する導電性炭素粉末は、二次電池の電池物性を高める観点から、オリビン型シリケート化合物と導電性炭素粉末の合計量１００質量％中に、好ましくは０．５〜２０質量％、より好ましくは２．５〜１７．５質量％となる量である。 From the viewpoint of enhancing the battery physical properties of the secondary battery, the conductive carbon powder charged into the sealed container is preferably 0.5 to 20 mass in a total amount of 100 mass% of the olivine silicate compound and the conductive carbon powder. %, More preferably 2.5 to 17.5% by mass.
なお、複合粒子を形成する前に、導電性炭素材料を用い、予め得られたオリビン型シリケート化合物の一次粒子又は二次粒子にカーボン担持する処理を施してもよい。このようにすることで、予め粒子表面にカーボン薄膜を形成されることができ、オリビン型シリケート化合物の電子伝導面積（電子伝導パス）をさらに増加させ、より十分な電子伝導性を確保することが可能となる。 In addition, before forming the composite particles, a conductive carbon material may be used to carry out a carbon support treatment on primary particles or secondary particles of an olivine silicate compound obtained in advance. By doing so, a carbon thin film can be formed on the particle surface in advance, and the electron conduction area (electron conduction path) of the olivine-type silicate compound can be further increased to ensure more sufficient electron conductivity. It becomes possible.
カーボン担持する処理は、水熱反応させる前であってもよく、水熱反応後における乾燥工程の際に行ってもよい。導電性炭素材料としては、例えば、セルロース、リグニン、キトサン、キチン、カーボンナノチューブ、グラフェン、グラフェンオキサイド、カーボンブラック、アセチレンブラック、ケッチェンブラック、黒鉛、グラファイト、合成繊維等の炭素含有化合物を用いることができる。この際における導電性炭素材料の添加量は、水熱反応後に得られるオリビン型シリケート化合物の一次粒子理論生成量中に、導電性炭素材料に含まれる炭素原子換算で、０．５〜２０質量％となる量で添加するのが好ましく、２．５〜１７．５質量％となる量で添加するのがより好ましい。導電性炭素材料を添加するにあたり、分散性を高める点から、溶媒を用いて溶液とするのがよい。かかる溶液中の導電性炭素材料の濃度は、好ましくは４０質量％以下であり、より好ましくは２０質量％以下である。溶媒としては、例えば、蒸留水、イオン交換水等が挙げられる。導電性炭素材料を添加する態様としては、導電性炭素材料の溶液に、リチウム含有化合物、遷移金属源及びケイ酸化合物を含む水分散液等の混合物を添加してもよく、かかる混合物に、導電性炭素材料の溶液を添加してもよい。これらをすべて混合した後、水熱反応に付せばよい。 The treatment for supporting carbon may be performed before the hydrothermal reaction, or may be performed during the drying step after the hydrothermal reaction. Examples of the conductive carbon material include carbon-containing compounds such as cellulose, lignin, chitosan, chitin, carbon nanotubes, graphene, graphene oxide, carbon black, acetylene black, ketjen black, graphite, graphite, and synthetic fibers. it can. The amount of the conductive carbon material added in this case is 0.5 to 20% by mass in terms of carbon atoms contained in the conductive carbon material in the primary particle theoretical generation amount of the olivine-type silicate compound obtained after the hydrothermal reaction. Is preferably added in an amount of 2.5 to 17.5% by mass. In adding the conductive carbon material, it is preferable to use a solvent to form a solution from the viewpoint of improving dispersibility. The concentration of the conductive carbon material in the solution is preferably 40% by mass or less, and more preferably 20% by mass or less. Examples of the solvent include distilled water and ion exchange water. As a mode of adding the conductive carbon material, a mixture such as an aqueous dispersion containing a lithium-containing compound, a transition metal source, and a silicate compound may be added to the solution of the conductive carbon material. A solution of carbonaceous material may be added. All of these may be mixed and then subjected to a hydrothermal reaction.
また、水熱反応後の乾燥工程の際にカーボン担持する処理を行う場合、導電性炭素材料としては、グルコース、ポリビニルアルコール、カルボキシメチルセルロース、カーボンナノチューブ、グラフェン、グラフェンオキサイド、カーボンブラック、アセチレンブラック、ケッチェンブラック、黒鉛、グラファイトが好ましい。この際、例えば、グルコース等の有機化合物については、得られたオリビン型シリケート化合物の一次粒子及び導電性炭素材料を含有するスラリーを調製し、乾燥工程を経た後、一旦仮焼成して二次粒子を得ても良く、カーボンナノチューブ等の導電性炭素材料については、前述の仮焼成を省いても良い。スラリーには、適宜、有機バインダー、無機バインダーを含有させてもよい。この際における導電性炭素材料の添加量は、良好な充放電容量及び経済性の点から、スラリー中のオリビン型シリケート化合物の一次粒子１００質量部に対し、炭素原子換算で０．５〜２０質量部の量が好ましく、さらに２．５〜１７．５質量部の量が好ましい。かかる処理を施した後、上述した乾式下における圧縮力及びせん断力を付加しながらの混合処理に付せばよい。 In addition, in the case of performing a carbon support treatment in the drying step after the hydrothermal reaction, conductive carbon materials include glucose, polyvinyl alcohol, carboxymethyl cellulose, carbon nanotubes, graphene, graphene oxide, carbon black, acetylene black, kettle. Chain black, graphite and graphite are preferred. At this time, for example, for an organic compound such as glucose, a slurry containing primary particles of the obtained olivine-type silicate compound and a conductive carbon material is prepared, and after passing through a drying step, temporarily calcined to secondary particles. In the case of conductive carbon materials such as carbon nanotubes, the pre-baking described above may be omitted. The slurry may appropriately contain an organic binder and an inorganic binder. In this case, the conductive carbon material is added in an amount of 0.5 to 20 mass in terms of carbon atom with respect to 100 parts by mass of primary particles of the olivine silicate compound in the slurry from the viewpoint of good charge / discharge capacity and economy. The amount of parts is preferable, and the amount of 2.5 to 17.5 parts by mass is more preferable. After performing such a treatment, it may be subjected to the mixing treatment while applying the compressive force and shear force under the dry process described above.
次いで、乾式下における圧縮力及びせん断力を付加しながらの混合処理を施すことにより得られた複合粒子を大気雰囲気下にて２００〜３００℃で焼成する。これにより、ガスの取り扱いの危険性に配慮する必要がなく、また特定の焼成装置に限られることなく、前工程において歪みが生じた結晶構造を復元して結晶配向性を高めることができるとともに、酸化状態にさらされた複合粒子の表面を元の状態に戻し、正極材料としての性能を向上させることができる。 Subsequently, the composite particles obtained by performing a mixing treatment while applying a compressive force and a shear force under a dry process are fired at 200 to 300 ° C. in an air atmosphere. Thereby, it is not necessary to consider the danger of gas handling, and without being limited to a specific baking apparatus, it is possible to restore the crystal structure in which distortion occurred in the previous process and improve the crystal orientation, The surface of the composite particles exposed to the oxidized state can be returned to the original state, and the performance as the positive electrode material can be improved.
焼成温度は、導電性炭素材料の熱分解、或いは焼成が過度に進行するのを抑制して、得られる粒子における適度な表面積を確保する観点、複合粒子内に生じた歪みを効果的に除去し、オリビン型シリケート化合物の酸化分解を抑制する観点から、２００〜３００℃に調整するものであり、好ましくは２００〜２５０℃、より好ましくは２２０〜２５０℃に調整する。焼成時間は、好ましくは０時間を超え２４時間以下であり、より好ましくは０．５〜３時間である。また、焼成時における大気流量は、好ましくは０．１〜１０００ｍｌ／分であり、より好ましくは１〜３００ｍｌ／分である。 The firing temperature suppresses the thermal decomposition of the conductive carbon material or the excessive progress of firing, and effectively removes the distortion generated in the composite particles from the viewpoint of securing an appropriate surface area in the obtained particles. From the viewpoint of suppressing the oxidative degradation of the olivine-type silicate compound, the temperature is adjusted to 200 to 300 ° C, preferably 200 to 250 ° C, more preferably 220 to 250 ° C. The firing time is preferably more than 0 hour and 24 hours or less, and more preferably 0.5 to 3 hours. The atmospheric flow rate during firing is preferably 0.1 to 1000 ml / min, more preferably 1 to 300 ml / min.
上記焼成温度に達するまでの昇温速度は特に制限されないが、複合粒子内に生じた歪みをより効果的に除去し得る観点から、３〜３０℃／分で焼成温度に達するまで一定に設定するのが好ましく、５〜１５℃／分で焼成温度に達するまで一定に設定するのがより好ましい。また、冷却速度は特に制限されず、適宜設定することができる。 The rate of temperature rise until reaching the firing temperature is not particularly limited, but is set to a constant temperature until reaching the firing temperature at 3 to 30 ° C./min from the viewpoint of more effectively removing the distortion generated in the composite particles. It is more preferable to set the pressure constant at 5 to 15 ° C./min until the firing temperature is reached. The cooling rate is not particularly limited and can be set as appropriate.
焼成後に得られる複合粒子の結晶子サイズは、複合粒子の粒成長を抑制して二次電池の電池物性を高める観点から、好ましくは７０ｎｍ以下であり、より好ましくは２０〜５０ｎｍである。なお、結晶子サイズは、ＸＲＤにより測定することができる。 The crystallite size of the composite particles obtained after firing is preferably 70 nm or less, more preferably 20 to 50 nm, from the viewpoint of suppressing the grain growth of the composite particles and improving the battery physical properties of the secondary battery. The crystallite size can be measured by XRD.
焼成に用いる装置としては、上記温度等を調整し得るものであれば特に制限されず、バッチ式、連続式、過熱方式（直接又は間接）のいずれであってもよい。具体的には、例えば、外熱キルン、ローラーハース炉等を用いることができる。 The apparatus used for firing is not particularly limited as long as the temperature and the like can be adjusted, and may be any of a batch system, a continuous system, and a superheating system (direct or indirect). Specifically, for example, an external heat kiln, a roller hearth furnace, or the like can be used.
このようにして得られた本発明の二次電池用正極材料を用いて二次電池を製造する方法は特に限定されず、公知の方法をいずれも使用できる。例えば、かかる正極材料を結着剤や溶剤等の添加剤とともに混合して塗工液を得る。この際、必要に応じて、さらに導電助剤を添加して混合してもよい。かかる結着剤としては、特に限定されず、公知の剤をいずれも使用できる。具体的には、ポリテトラフルオロエチレン、ポリビニリデンフルオライド、ポリビニルクロライド、エチレンプロピレンジエンポリマー等が挙げられる。また、かかる導電助剤としては、特に限定されず、公知の剤をいずれも使用できる。具体的には、アセチレンブラック、ケッチェンブラック、天然黒鉛、人工黒鉛、繊維状炭素等が挙げられる。次いで、かかる塗工液をアルミ箔等の正極集電体上に塗布し、乾燥させて正極とする。 The method for producing the secondary battery using the positive electrode material for the secondary battery of the present invention thus obtained is not particularly limited, and any known method can be used. For example, such a positive electrode material is mixed with additives such as a binder and a solvent to obtain a coating liquid. At this time, if necessary, a conductive additive may be further added and mixed. The binder is not particularly limited, and any known agent can be used. Specific examples include polytetrafluoroethylene, polyvinylidene fluoride, polyvinyl chloride, and ethylene propylene diene polymer. Moreover, it does not specifically limit as this conductive support agent, Any well-known agent can be used. Specific examples include acetylene black, ketjen black, natural graphite, artificial graphite, and fibrous carbon. Next, such a coating solution is applied onto a positive electrode current collector such as an aluminum foil and dried to obtain a positive electrode.
本発明の二次電池用正極材料は、二次電池の正極として非常に優れた放電容量を発揮する点で有用である。かかる正極を適用できる二次電池としては、リチウムイオン二次電池であればよく、正極と負極と電解液とセパレータを必須構成とするものであれば特に限定されない。 The positive electrode material for a secondary battery of the present invention is useful in that it exhibits a very excellent discharge capacity as a positive electrode of a secondary battery. The secondary battery to which such a positive electrode can be applied is not particularly limited as long as it is a lithium ion secondary battery and has a positive electrode, a negative electrode, an electrolyte solution, and a separator as essential components.
ここで、負極については、リチウムイオンを充電時には吸蔵し、かつ放電時には放出することができれば、その材料構成で特に限定されるものではなく、公知の材料構成のものを用いることができる。たとえば、リチウム金属、グラファイト又は非晶質炭素等の炭素材料等である。そしてリチウムを電気化学的に吸蔵・放出し得るインターカレート材料で形成された電極、特に炭素材料を用いることが好ましい。 Here, as long as lithium ions can be occluded at the time of charging and released at the time of discharging, the material structure is not particularly limited, and a known material structure can be used. For example, a carbon material such as lithium metal, graphite, or amorphous carbon. It is preferable to use an electrode formed of an intercalating material capable of electrochemically inserting and extracting lithium, particularly a carbon material.
電解液は、有機溶媒に支持塩を溶解させたものである。有機溶媒は、通常リチウムイオン二次電池の電解液の用いられる有機溶媒であれば特に限定されるものではなく、例えば、カーボネート類、ハロゲン化炭化水素、エーテル類、ケトン類、ニトリル類、ラクトン類、オキソラン化合物等を用いることができる。 The electrolytic solution is obtained by dissolving a supporting salt in an organic solvent. The organic solvent is not particularly limited as long as it is an organic solvent that is usually used for an electrolyte solution of a lithium ion secondary battery. For example, carbonates, halogenated hydrocarbons, ethers, ketones, nitriles, lactones An oxolane compound or the like can be used.
支持塩は、その種類が特に限定されるものではないが、ＬｉＰＦ6、ＬｉＢＦ4、ＬｉＣｌＯ4及びＬｉＡｓＦ6から選ばれる無機塩、該無機塩の誘導体、ＬｉＳＯ3ＣＦ3、ＬｉＣ（ＳＯ3ＣＦ3）2及びＬｉＮ（ＳＯ3ＣＦ3）2、ＬｉＮ（ＳＯ2Ｃ2Ｆ5）2及びＬｉＮ（ＳＯ2ＣＦ3）（ＳＯ2Ｃ4Ｆ9）から選ばれる有機塩、並びに該有機塩の誘導体の少なくとも１種であることが好ましい。 The type of the supporting salt is not particularly limited, but an inorganic salt selected from LiPF 6 , LiBF 4 , LiClO 4 and LiAsF 6 , a derivative of the inorganic salt, LiSO 3 CF 3 , LiC (SO 3 CF 3 ) 2 and LiN (SO 3 CF 3 ) 2 , LiN (SO 2 C 2 F 5 ) 2 and LiN (SO 2 CF 3 ) (SO 2 C 4 F 9 ), and organic salt derivatives It is preferable that it is at least 1 sort of.
セパレータは、正極及び負極を電気的に絶縁し、電解液を保持する役割を果たすものである。たとえば、多孔性合成樹脂膜、特にポリオレフィン系高分子（ポリエチレン、ポリプロピレン）の多孔膜を用いればよい。 The separator plays a role of electrically insulating the positive electrode and the negative electrode and holding the electrolytic solution. For example, a porous synthetic resin film, particularly a polyolefin polymer (polyethylene, polypropylene) porous film may be used.
以下、本発明について、実施例に基づき具体的に説明するが、本発明はこれら実施例に限定されるものではない。 EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example, this invention is not limited to these Examples.
［製造例１］
ＬｉＯＨ・Ｈ2Ｏ ４２．０ｇ（１．０ｍｏｌ）、Ｎａ4ＳｉＯ4・ｎＨ2Ｏ １４０．０ｇ（０．５ｍｏｌ）、Ｎａ2Ｓ2Ｏ4 ８．７ｇ（０．０５ｍｏｌ）に超純水４００ｃｍ3を加えて混合した（この時のｐＨは約１３）。この水分散液にＦｅＳＯ4・７Ｈ2Ｏ６２．６ｇ（０．２２５ｍｏｌ）、ＭｎＳＯ4・５Ｈ2Ｏ ５４．２ｇ（０．２２５ｍｏｌ）及びＺｒ（ＳＯ4）2・４Ｈ2Ｏ７．１ｇ（０．０２５ｍｏｌ）を添加し、混合した。なお、水分散液中におけるリチウム化合物の濃度は、２．５０ｍｏｌ／ｌ、ケイ酸化合物の濃度は１．２５ｍｏｌ／ｌであり、混合液中における遷移金属硫酸塩の濃度は、１．１８ｍｏｌ／ｌであった。
得られた混合液をオートクレーブに投入し、１７０℃で６ｈｒ水熱反応を行った。次いで、反応液をろ過し、ケーキ状のオリビン型シリケート化合物を得た。
得られたケーキの水分量は５３質量％であり、オリビン型シリケート化合物（一次粒子）の平均粒径は、４５ｎｍであった。
[Production Example 1]
LiOH.H 2 O 42.0 g (1.0 mol), Na 4 SiO 4 .nH 2 O 140.0 g (0.5 mol), Na 2 S 2 O 4 8.7 g (0.05 mol) and ultrapure water 400 cm 3 was added and mixed (the pH at this time was about 13). In this aqueous dispersion, 62.6 g (0.225 mol) of FeSO 4 .7H 2 O, 54.2 g (0.225 mol) of MnSO 4 .5H 2 O and 7.1 g (0.025 mol) of Zr (SO 4 ) 2 .4H 2 O were added. ) Was added and mixed. The concentration of the lithium compound in the aqueous dispersion is 2.50 mol / l, the concentration of the silicate compound is 1.25 mol / l, and the concentration of the transition metal sulfate in the mixture is 1.18 mol / l. Met.
The obtained mixed liquid was put into an autoclave and subjected to a hydrothermal reaction at 170 ° C. for 6 hours. Subsequently, the reaction solution was filtered to obtain a cake-like olivine-type silicate compound.
The obtained cake had a water content of 53% by mass, and the average particle size of the olivine-type silicate compound (primary particles) was 45 nm.
［実施例１］
製造例１で得られた一次粒子の固形分２００ｇに対し、水分量の合計が３００ｇとなるように超純水を加え、得られた一次粒子の含有量を４０質量％として、スラリーを調整し、下記条件で噴霧乾燥装置（４流体ノズルを備えたマイクロミストドライヤー：藤崎電気（株）製）を用い、造粒した。
エアー圧：０．６ＭＰａ
エアー流量：５０ＬＮ／ｍｉｎ
熱風量：１．０ｍ3／ｍｉｎ
入口温度：１８０℃
排気温度：１００℃
スラリー流量：６０ｇ／ｍｉｎ
得られた粉末（二次粒子）の平均粒径は、７μｍであった。
[Example 1]
To 200 g of the solid content of the primary particles obtained in Production Example 1, ultrapure water was added so that the total amount of water was 300 g, and the content of the obtained primary particles was 40% by mass to adjust the slurry. Then, granulation was performed using a spray drying apparatus (micro mist dryer equipped with a four-fluid nozzle: manufactured by Fujisaki Electric Co., Ltd.) under the following conditions.
Air pressure: 0.6 MPa
Air flow rate: 50LN / min
Hot air volume: 1.0 m 3 / min
Inlet temperature: 180 ° C
Exhaust temperature: 100 ° C
Slurry flow rate: 60 g / min
The average particle diameter of the obtained powder (secondary particles) was 7 μm.
次いで、得られた粉末（二次粒子）１３５ｇとケッチェンブラック（ライオン社製、平均粒径３０ｎｍ）１５ｇとを予め混合して混合物を得て、得られた混合物を微粒子複合化装置 ノビルタ（ホソカワミクロン社製）に投入し、インペラの周速３０ｍ／ｓ、回転数６０００ｒｐｍの条件下、５５℃で３０分間混合して、複合粒子Ａを得た。得られた複合粒子の平均粒径は２４μｍであった。
得られた複合粒子は、大気を２００ｍｌ/分の流量で流した管状電気炉にて、２００℃で１ｈｒ焼成した。なお、かかる焼成温度に達するまでの昇温速度は１０℃／分であった。また、ＸＲＤにより測定した結晶子サイズは、３４．４ｎｍであった。
Next, 135 g of the obtained powder (secondary particles) and 15 g of ketjen black (manufactured by Lion Corporation, average particle size 30 nm) were mixed in advance to obtain a mixture, and the resulting mixture was mixed with a fine particle composite apparatus Nobilta (Hosokawa Micron). And mixed at 55 ° C. for 30 minutes under conditions of an impeller peripheral speed of 30 m / s and a rotation speed of 6000 rpm, to obtain composite particles A. The average particle size of the obtained composite particles was 24 μm.
The obtained composite particles were fired at 200 ° C. for 1 hr in a tubular electric furnace in which air was flowed at a flow rate of 200 ml / min. In addition, the temperature increase rate until reaching this baking temperature was 10 degreeC / min. The crystallite size measured by XRD was 34.4 nm.
次いで、得られた焼成後の複合粒子（焼成物Ａ）を用い、リチウムイオン二次電池の正極を作製した。得られた焼成物、ケッチェンブラック（導電剤）、ポリフッ化ビニリデン（粘結剤）を重量比７５：１５：１０の配合割合で混合し、これにＮ−メチル−２−ピロリドンを加えて充分混練し、正極スラリーを調製した。正極スラリーを厚さ２０μｍのアルミニウム箔からなる集電体に塗工機を用いて塗布し、８０℃で１２時間の真空乾燥を行った。その後、φ１４ｍｍの円盤状に打ち抜いてハンドプレスを用いて１６ＭＰａで２分間プレスし、正極とした。 Subsequently, the positive electrode of the lithium ion secondary battery was produced using the obtained composite particles after firing (fired product A). The obtained fired product, ketjen black (conductive agent), and polyvinylidene fluoride (binding agent) are mixed at a mixing ratio of 75:15:10, and N-methyl-2-pyrrolidone is added to the mixture. The mixture was kneaded to prepare a positive electrode slurry. The positive electrode slurry was applied to a current collector made of an aluminum foil having a thickness of 20 μm using a coating machine, and vacuum dried at 80 ° C. for 12 hours. Thereafter, it was punched into a disk shape of φ14 mm and pressed at 16 MPa for 2 minutes using a hand press to obtain a positive electrode.
次いで、上記の正極を用いてコイン型リチウムイオン二次電池を構築した。負極には、φ１５ｍｍに打ち抜いたリチウム箔を用いた。電解液には、エチレンカーボネート及びエチルメチルカーボネートを体積比１：１の割合で混合した混合溶媒に、ＬＩＰＦ6を１ｍｏｌ／ｌの濃度で溶解したものを用いた。セパレータには、ポリプロピレン等の高分子多孔フィルム等、公知のものを用いた。これらの電池部品を露点が−５０℃以下の雰囲気で常法により組み込み収容し、コイン型リチウム二次電池（ＣＲ−２０３２）を製造した。 Next, a coin-type lithium ion secondary battery was constructed using the positive electrode. A lithium foil punched to φ15 mm was used for the negative electrode. As the electrolytic solution, a solution obtained by dissolving LIPF 6 at a concentration of 1 mol / l in a mixed solvent in which ethylene carbonate and ethyl methyl carbonate were mixed at a volume ratio of 1: 1 was used. As the separator, a known one such as a polymer porous film such as polypropylene was used. These battery components were assembled and housed in a conventional manner in an atmosphere with a dew point of −50 ° C. or lower to produce a coin-type lithium secondary battery (CR-2032).
製造したリチウムイオン二次電池を用いて定電流密度での充放電を１サイクル行った。このときの充電条件は電流０．１ＣＡ（３３ｍＡ／ｇ）、電圧４．５Ｖの定電流定電圧充電とし、放電条件は電流０．１ＣＡ、終止電圧１．５Ｖの定電流放電とした。温度は全て３０℃とした。実施例１で得られた正極材で構築した電池の充放電容量を表１に示す。 One cycle of charge and discharge at a constant current density was performed using the manufactured lithium ion secondary battery. The charging conditions at this time were constant current and constant voltage charging with a current of 0.1 CA (33 mA / g) and a voltage of 4.5 V, and the discharging conditions were constant current discharging with a current of 0.1 CA and a final voltage of 1.5 V. All temperatures were 30 ° C. Table 1 shows the charge / discharge capacity of the battery constructed with the positive electrode material obtained in Example 1.
［実施例２］
製造例１の一次粒子を用いて得られた複合粒子を２５０℃で１ｈｒ焼成した以外、実施例１と同様にして粉末（二次粒子、平均粒径２４μｍ）を得た後、実施例１と同様にして焼成物Ｂを得た。なお、焼成温度に達するまでの昇温速度は１０℃／分であった。また、ＸＲＤにより測定した結晶子サイズは、３４．２ｎｍであった。
次いで正極を作製して電池を構築した。かかる電池を用い、実施例１と同様の条件下にて充放電を１サイクル行ったときの充放電容量を表１に示す。
[Example 2]
After obtaining a powder (secondary particles, average particle size of 24 μm) in the same manner as in Example 1 except that the composite particles obtained using the primary particles of Production Example 1 were fired at 250 ° C. for 1 hr, Example 1 and Similarly, a fired product B was obtained. The rate of temperature increase until reaching the firing temperature was 10 ° C./min. The crystallite size measured by XRD was 34.2 nm.
Next, a positive electrode was produced to construct a battery. Table 1 shows the charge / discharge capacity when one cycle of charge / discharge is performed under the same conditions as in Example 1 using such a battery.
［比較例１］
製造例１の一次粒子を用いて得られた複合粒子を１５０℃で１ｈｒ焼成した以外、実施例１と同様にして粉末（二次粒子、平均粒径２４μｍ）を得た後、実施例１と同様にして焼成物Ｃを得た。
次いで正極を作製して電池を構築した。かかる電池を用い、実施例１と同様の条件下にて充放電を１サイクル行ったときの充放電容量を表１に示す。
[Comparative Example 1]
A powder (secondary particle, average particle size 24 μm) was obtained in the same manner as in Example 1 except that the composite particles obtained using the primary particles of Production Example 1 were calcined at 150 ° C. for 1 hr, and then Example 1 and Similarly, a fired product C was obtained.
Next, a positive electrode was produced to construct a battery. Table 1 shows the charge / discharge capacity when one cycle of charge / discharge is performed under the same conditions as in Example 1 using such a battery.
［比較例２］
製造例１の一次粒子を用いて得られた複合粒子を３５０℃で１ｈｒ焼成した以外、実施例１と同様にして粉末（二次粒子、平均粒径２４μｍ）を得た後、実施例１と同様にして焼成物Ｄを得た。
次いで正極を作製して電池を構築した。かかる電池を用い、実施例１と同様の条件下にて充放電を１サイクル行ったときの充放電容量を表１に示す。
[Comparative Example 2]
A powder (secondary particle, average particle size 24 μm) was obtained in the same manner as in Example 1 except that the composite particles obtained using the primary particles of Production Example 1 were calcined at 350 ° C. for 1 hr. Similarly, a fired product D was obtained.
Next, a positive electrode was produced to construct a battery. Table 1 shows the charge / discharge capacity when one cycle of charge / discharge is performed under the same conditions as in Example 1 using such a battery.
［比較例３］
製造例１の一次粒子を用いて得られた複合粒子を、Ｈ2３％（Ａｒバランス）の混合ガスを２００ｍｌ/分の流量で流した管状電気炉にて、６００℃で１ｈｒ焼成した以外、実施例１と同様にして粉末（二次粒子、平均粒径２４μｍ）を得た後、実施例１と同様にして焼成物Ｅを得た。
次いで正極を作製して電池を構築した。かかる電池を用い、実施例１と同様の条件下にて充放電を１サイクル行ったときの充放電容量を表１に示す。
[Comparative Example 3]
The composite particles obtained using the primary particles in Production Example 1 were calcined at 600 ° C. for 1 hr in a tubular electric furnace in which a mixed gas of H 2 3% (Ar balance) was flowed at a flow rate of 200 ml / min, After obtaining a powder (secondary particles, average particle size of 24 μm) in the same manner as in Example 1, fired product E was obtained in the same manner as in Example 1.
Next, a positive electrode was produced to construct a battery. Table 1 shows the charge / discharge capacity when one cycle of charge / discharge is performed under the same conditions as in Example 1 using such a battery.
表１の結果により、実施例１〜２で得られた電池は、比較例１〜３に比して、優れた電池物性を有することがわかる。 From the results shown in Table 1, it can be seen that the batteries obtained in Examples 1 and 2 have superior battery properties as compared with Comparative Examples 1 to 3.
［導電率の測定］
粉体抵抗測定システム（三菱化学アナリテック）を用い、実施例２で得られた焼成物Ｂの２０ｋＮ加圧下における導電率を測定したところ、１０-2Ｓ／ｃｍであった。
[Measurement of conductivity]
Using a powder resistance measurement system (Mitsubishi Chemical Analytech), the conductivity of the fired product B obtained in Example 2 under a 20 kN pressure was measured and found to be 10 -2 S / cm.
Claims (11)
得られた二次粒子及び導電性炭素粉末を乾式下にて圧縮力及びせん断力を付加しながら混合することにより、複合粒子を形成し、
次いで、得られた複合粒子を大気雰囲気下にて２００〜３００℃で焼成することを特徴とする、二次電池用正極材料の製造方法。 The primary particles of the olivine-type silicate compound obtained by the hydrothermal reaction are dried to form secondary particles,
By mixing the obtained secondary particles and conductive carbon powder while applying compressive force and shear force under a dry process, composite particles are formed,
Subsequently, the obtained composite particles are fired at 200 to 300 ° C. in an air atmosphere, and a method for producing a positive electrode material for a secondary battery.
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