JP6264410B2 - Non-aqueous secondary battery positive electrode composition and method for producing the same - Google Patents
Non-aqueous secondary battery positive electrode composition and method for producing the same Download PDFInfo
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- 239000000203 mixture Substances 0.000 title claims description 98
- 238000004519 manufacturing process Methods 0.000 title claims description 21
- 239000002245 particle Substances 0.000 claims description 184
- 239000010936 titanium Substances 0.000 claims description 84
- 229910052719 titanium Inorganic materials 0.000 claims description 84
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 claims description 81
- 229910052723 transition metal Inorganic materials 0.000 claims description 52
- 229910052744 lithium Inorganic materials 0.000 claims description 48
- -1 lithium transition metal Chemical class 0.000 claims description 48
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims description 47
- 239000002905 metal composite material Substances 0.000 claims description 47
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 40
- 239000001301 oxygen Substances 0.000 claims description 40
- 229910052760 oxygen Inorganic materials 0.000 claims description 40
- 238000010438 heat treatment Methods 0.000 claims description 35
- 239000007774 positive electrode material Substances 0.000 claims description 32
- 238000000034 method Methods 0.000 claims description 21
- 229910052759 nickel Inorganic materials 0.000 claims description 21
- 238000002156 mixing Methods 0.000 claims description 16
- 229910052782 aluminium Inorganic materials 0.000 claims description 5
- 229910052749 magnesium Inorganic materials 0.000 claims description 4
- 229910052750 molybdenum Inorganic materials 0.000 claims description 4
- 229910052758 niobium Inorganic materials 0.000 claims description 4
- 229910052715 tantalum Inorganic materials 0.000 claims description 4
- 229910052721 tungsten Inorganic materials 0.000 claims description 4
- 229910052726 zirconium Inorganic materials 0.000 claims description 4
- 238000003860 storage Methods 0.000 description 26
- 238000007600 charging Methods 0.000 description 24
- 238000011156 evaluation Methods 0.000 description 17
- 230000000052 comparative effect Effects 0.000 description 12
- 239000011255 nonaqueous electrolyte Substances 0.000 description 12
- 239000002131 composite material Substances 0.000 description 11
- 238000007599 discharging Methods 0.000 description 8
- 239000011572 manganese Substances 0.000 description 6
- 238000010280 constant potential charging Methods 0.000 description 5
- RSNHXDVSISOZOB-UHFFFAOYSA-N lithium nickel Chemical compound [Li].[Ni] RSNHXDVSISOZOB-UHFFFAOYSA-N 0.000 description 5
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 4
- 239000011267 electrode slurry Substances 0.000 description 4
- 230000014759 maintenance of location Effects 0.000 description 4
- 238000006467 substitution reaction Methods 0.000 description 4
- OGIDPMRJRNCKJF-UHFFFAOYSA-N titanium oxide Inorganic materials [Ti]=O OGIDPMRJRNCKJF-UHFFFAOYSA-N 0.000 description 4
- 150000003624 transition metals Chemical class 0.000 description 4
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 3
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical group [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 3
- 239000010941 cobalt Substances 0.000 description 3
- 229910017052 cobalt Inorganic materials 0.000 description 3
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical group [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 description 3
- CKFRRHLHAJZIIN-UHFFFAOYSA-N cobalt lithium Chemical compound [Li].[Co] CKFRRHLHAJZIIN-UHFFFAOYSA-N 0.000 description 3
- 238000009826 distribution Methods 0.000 description 3
- 229910001416 lithium ion Inorganic materials 0.000 description 3
- 238000012423 maintenance Methods 0.000 description 3
- 229910052748 manganese Inorganic materials 0.000 description 3
- 238000012545 processing Methods 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- 238000001291 vacuum drying Methods 0.000 description 3
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- 229910003782 Li1.08Ni0.5Co0.2Mn0.3O2 Inorganic materials 0.000 description 2
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 2
- OLBVUFHMDRJKTK-UHFFFAOYSA-N [N].[O] Chemical compound [N].[O] OLBVUFHMDRJKTK-UHFFFAOYSA-N 0.000 description 2
- 239000011149 active material Substances 0.000 description 2
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 2
- 239000008151 electrolyte solution Substances 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-M hydroxide Chemical compound [OH-] XLYOFNOQVPJJNP-UHFFFAOYSA-M 0.000 description 2
- 239000011777 magnesium Substances 0.000 description 2
- 239000012046 mixed solvent Substances 0.000 description 2
- 239000010955 niobium Substances 0.000 description 2
- 238000002360 preparation method Methods 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 238000011084 recovery Methods 0.000 description 2
- 238000000790 scattering method Methods 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 229920002134 Carboxymethyl cellulose Polymers 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 1
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 1
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 description 1
- 229910016722 Ni0.5Co0.2Mn0.3 Inorganic materials 0.000 description 1
- 239000002033 PVDF binder Substances 0.000 description 1
- 239000004698 Polyethylene Substances 0.000 description 1
- QCWXUUIWCKQGHC-UHFFFAOYSA-N Zirconium Chemical compound [Zr] QCWXUUIWCKQGHC-UHFFFAOYSA-N 0.000 description 1
- KLARSDUHONHPRF-UHFFFAOYSA-N [Li].[Mn] Chemical compound [Li].[Mn] KLARSDUHONHPRF-UHFFFAOYSA-N 0.000 description 1
- 239000006230 acetylene black Substances 0.000 description 1
- 229910052786 argon Inorganic materials 0.000 description 1
- 229910021383 artificial graphite Inorganic materials 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000001768 carboxy methyl cellulose Substances 0.000 description 1
- 235000010948 carboxy methyl cellulose Nutrition 0.000 description 1
- 239000008112 carboxymethyl-cellulose Substances 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000000975 co-precipitation Methods 0.000 description 1
- 238000010277 constant-current charging Methods 0.000 description 1
- 239000011889 copper foil Substances 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 230000001186 cumulative effect Effects 0.000 description 1
- 230000001351 cycling effect Effects 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 238000003487 electrochemical reaction Methods 0.000 description 1
- 238000010828 elution Methods 0.000 description 1
- JBTWLSYIZRCDFO-UHFFFAOYSA-N ethyl methyl carbonate Chemical compound CCOC(=O)OC JBTWLSYIZRCDFO-UHFFFAOYSA-N 0.000 description 1
- 239000011888 foil Substances 0.000 description 1
- 230000004927 fusion Effects 0.000 description 1
- 239000011261 inert gas Substances 0.000 description 1
- XGZVUEUWXADBQD-UHFFFAOYSA-L lithium carbonate Chemical compound [Li+].[Li+].[O-]C([O-])=O XGZVUEUWXADBQD-UHFFFAOYSA-L 0.000 description 1
- 229910052808 lithium carbonate Inorganic materials 0.000 description 1
- 229910021439 lithium cobalt complex oxide 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
- 229910021440 lithium nickel complex oxide Inorganic materials 0.000 description 1
- 238000013507 mapping Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000011733 molybdenum Substances 0.000 description 1
- CQDGTJPVBWZJAZ-UHFFFAOYSA-N monoethyl carbonate Chemical compound CCOC(O)=O CQDGTJPVBWZJAZ-UHFFFAOYSA-N 0.000 description 1
- GUCVJGMIXFAOAE-UHFFFAOYSA-N niobium atom Chemical compound [Nb] GUCVJGMIXFAOAE-UHFFFAOYSA-N 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 229920000573 polyethylene Polymers 0.000 description 1
- 229920002981 polyvinylidene fluoride Polymers 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- 229920003048 styrene butadiene rubber Polymers 0.000 description 1
- 238000003786 synthesis reaction Methods 0.000 description 1
- GUVRBAGPIYLISA-UHFFFAOYSA-N tantalum atom Chemical compound [Ta] GUVRBAGPIYLISA-UHFFFAOYSA-N 0.000 description 1
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 description 1
- 239000010937 tungsten Substances 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
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
本開示は、リチウムイオン二次電池等の非水系二次電池の正極に用いられる組成物およびその製造方法に関する。 The present disclosure relates to a composition used for a positive electrode of a non-aqueous secondary battery such as a lithium ion secondary battery and a method for producing the same.
リチウムイオン二次電池等の非水系二次電池は、携帯電話、ノートパソコン等の小型機器用電源として普及している。非水系二次電池は、平均動作電圧を高くすることが可能なので、電気自動車等の大型機器の動力用電源としても検討されている。 Non-aqueous secondary batteries such as lithium ion secondary batteries are widely used as power sources for small devices such as mobile phones and notebook computers. Since non-aqueous secondary batteries can increase the average operating voltage, they are also being studied as power sources for large equipment such as electric vehicles.
非水系二次電池の正極にはリチウムコバルト複合酸化物のようなリチウム遷移金属複合酸化物が活物質として用いられるのが一般的である。遷移金属にニッケルを用いたリチウム遷移金属複合酸化物（リチウムニッケル系複合酸化物）は、リチウムコバルト複合酸化物以上に単位質量当たりの容量が大きいため、大型機器の動力用電源用の非水系二次電池の正極活物質として期待されている。 Generally, a lithium transition metal composite oxide such as a lithium cobalt composite oxide is used as an active material for a positive electrode of a non-aqueous secondary battery. Lithium transition metal complex oxides (lithium nickel complex oxides) using nickel as the transition metal have a larger capacity per unit mass than lithium cobalt complex oxides. It is expected as a positive electrode active material for secondary batteries.
さらに、ホウ化チタンと正極活物質とを混合して正極組成物とする例も存在する。 Further, there is an example in which titanium boride and a positive electrode active material are mixed to form a positive electrode composition.
特許文献１には、組成式Ｌｉ１．１Ｎｉ０．３Ｃｏ０．４Ｍｎ０．３Ｏ２で表されるリチウム遷移金属複合酸化物粒子からなる正極活物質と、平均粒径が２μｍのＴｉＢ２粒子とを、モル比で９９：１となるよう混合した例が記載されている。混合後、得られた混合物を焼成し、リチウム遷移金属複合酸化物粒子の表面にＴｉＢ２粒子を焼結させた例も記載されている。 Patent Document 1 discloses a positive electrode active material composed of lithium transition metal composite oxide particles represented by a composition formula Li 1.1 Ni 0.3 Co 0.4 Mn 0.3 O 2 and an average particle diameter of 2 μm. and TiB 2 particles, 99 in a molar ratio: example were mixed 1 become as has been described. An example is also described in which the obtained mixture is fired after mixing, and TiB 2 particles are sintered on the surface of the lithium transition metal composite oxide particles.
特許文献２には、リチウムニッケル複合酸化物からなる正極活物質の表面に、５重量％のＴｉＢ２粒子を融合させた例が記載されている。融合は、ＴｉＢ２粒子に機械的エネルギーを与えることによってなされたとされている。ＴｉＢ２粒子の平均粒径、粒度等は不明である。 Patent Document 2 describes an example in which 5% by weight of TiB 2 particles are fused on the surface of a positive electrode active material made of a lithium nickel composite oxide. The fusion is said to have been done by applying mechanical energy to the TiB 2 particles. The average particle size and particle size of the TiB 2 particles are unknown.
電気自動車のような大型機器の動力用電源として非水系二次電池を用いる場合、非水系二次電池のエネルギー密度を高めるためにより高い充電電圧で用いることが多い。しかしながら、充電電圧を４．３Ｖ以上の高電圧にして非水系二次電池を用いると、サイクル特性等が顕著に悪化し得ることが分かった。特にリチウムニッケル系複合酸化物を正極活物質に用いた非水系二次電池においてその傾向が強いことが分かった。 When a non-aqueous secondary battery is used as a power source for large equipment such as an electric vehicle, it is often used at a higher charging voltage in order to increase the energy density of the non-aqueous secondary battery. However, it has been found that when the non-aqueous secondary battery is used with the charging voltage set to a high voltage of 4.3 V or higher, the cycle characteristics and the like can be significantly deteriorated. In particular, it was found that the tendency was strong in the non-aqueous secondary battery using the lithium nickel composite oxide as the positive electrode active material.
本開示の目的は、リチウムニッケル系複合酸化物を用いた非水系二次電池において、高電圧における、充放電特性、高温保存特性およびサイクル特性に優れた非水系二次電池を実現可能な正極組成物を提供することである。 An object of the present disclosure is to provide a positive electrode composition capable of realizing a non-aqueous secondary battery having excellent charge / discharge characteristics, high-temperature storage characteristics, and cycle characteristics at a high voltage in a non-aqueous secondary battery using a lithium nickel-based composite oxide. Is to provide things.
本開示の第一実施形態に係る非水系二次電池用正極組成物の製造方法は、ホウ化チタン粒子を酸素含有雰囲気下、１５０℃以上３００℃以下の熱処理温度で熱処理し、熱処理済み粒子を得る工程と、前記熱処理済み粒子と、組成にニッケルを含み層状構造を有するリチウム遷移金属複合酸化物粒子を含む正極活物質とを、前記熱処理済み粒子の前記リチウム遷移金属複合酸化物粒子に対する含有率が、チタンとして１．５ｍｏｌ％以下となるよう混合し、正極組成物を得る工程とを含むことを特徴とする。 In the method for producing a positive electrode composition for a non-aqueous secondary battery according to the first embodiment of the present disclosure, titanium boride particles are heat-treated at a heat treatment temperature of 150 ° C. or higher and 300 ° C. or lower in an oxygen-containing atmosphere. A content ratio of the heat-treated particles to the lithium-transition metal composite oxide particles, the step of obtaining, the heat-treated particles, and a positive electrode active material containing lithium transition metal composite oxide particles having a layered structure containing nickel Is mixed with the titanium so as to be 1.5 mol% or less to obtain a positive electrode composition.
第二実施形態に係る非水系二次電池用正極組成物は、ホウ化チタン粒子と、組成にニッケルを含み層状構造を有するリチウム遷移金属複合酸化物粒子を含む正極活物質とを含み、前記ホウ化チタン粒子は酸素成分を含み、その含有率が１．５重量％以上２．９重量％以下であり、前記ホウ化チタン粒子の前記リチウム遷移金属複合酸化物粒子に対する含有率が、チタンとして１．５ｍｏｌ％以下である。 A positive electrode composition for a non-aqueous secondary battery according to a second embodiment includes titanium boride particles and a positive electrode active material including lithium transition metal composite oxide particles having a layered structure containing nickel in the composition, The titanium boride particles contain an oxygen component, the content thereof is 1.5 wt% or more and 2.9 wt% or less, and the content of the titanium boride particles with respect to the lithium transition metal composite oxide particles is 1 as titanium. 0.5 mol% or less.
本発明の実施形態に係る非水系二次電池用正極組成物の製造方法によって得られる正極組成物を用いると、高電圧における充放電特性、高温保存特性およびサイクル特性に優れた非水系二次電池を実現することが可能になる。 When a positive electrode composition obtained by the method for manufacturing a positive electrode composition for a non-aqueous secondary battery according to an embodiment of the present invention is used, the non-aqueous secondary battery excellent in charge / discharge characteristics at high voltage, high-temperature storage characteristics and cycle characteristics Can be realized.
以下、本発明に係る非水系二次電池用正極組成物およびその製造方法を、実施の形態に基づいて説明する。ただし、以下に示す実施の形態は、本発明の技術思想を例示するものであって、本発明は、以下の非水系二次電池用正極組成物およびその製造方法に限定されない。本明細書において「工程」との語は、独立した工程だけではなく、他の工程と明確に区別できない場合であってもその工程の所期の目的が達成されれば、本用語に含まれる。また組成物中の各成分の含有量は、組成物中に各成分に該当する物質が複数存在する場合、特に断らない限り、組成物中に存在する当該複数の物質の合計量を意味する。リチウム遷移金属複合酸化物粒子およびホウ化チタン粒子の平均粒径は、レーザー散乱法によって得られる粒度分布の小径側からの体積累積５０％に対応する中心粒径である。 Hereinafter, a positive electrode composition for a non-aqueous secondary battery and a method for producing the same according to the present invention will be described based on embodiments. However, the embodiment described below exemplifies the technical idea of the present invention, and the present invention is not limited to the following positive electrode composition for a non-aqueous secondary battery and the manufacturing method thereof. In this specification, the term “process” is not limited to an independent process, and is included in the term if the intended purpose of the process is achieved even when it cannot be clearly distinguished from other processes. . Moreover, content of each component in a composition means the total amount of the said some substance which exists in a composition, unless there is particular notice, when the substance applicable to each component exists in a composition in multiple numbers. The average particle diameters of the lithium transition metal composite oxide particles and the titanium boride particles are the center particle diameters corresponding to 50% cumulative volume from the small diameter side of the particle size distribution obtained by the laser scattering method.
非水系二次電池用正極組成物の製造方法
本実施形態に係る非水系二次電池用正極組成物の製造方法は、熱処理済み粒子を得る工程と正極組成物を得る工程とを含む。以下これらを中心に説明する。
The manufacturing method of the positive electrode composition for non-aqueous secondary batteries The manufacturing method of the positive electrode composition for non-aqueous secondary batteries which concerns on this embodiment includes the process of obtaining heat-processed particle | grains, and the process of obtaining a positive electrode composition. These will be mainly described below.
＜熱処理済み粒子を得る工程＞
熱処理済み粒子を得る工程では、ホウ化チタン粒子を酸素含有雰囲気下で熱処理し、熱処理済み粒子を得る。熱処理前のホウ化チタン粒子の表面には、例えば、極めて薄い酸化チタンの層が形成されているが、酸素雰囲気下で熱処理することで、熱処理済み粒子の表面には、より厚い酸化チタンの層が形成されていると推測される。こうして得られる熱処理済み粒子を含む正極組成物を用いると、例えば、充電電圧４．３Ｖ以上の高電圧条件で使用した際の電池特性が優れたものになる。
<Process for obtaining heat-treated particles>
In the step of obtaining heat-treated particles, the titanium boride particles are heat-treated in an oxygen-containing atmosphere to obtain heat-treated particles. For example, an extremely thin titanium oxide layer is formed on the surface of the titanium boride particles before the heat treatment, but a thicker titanium oxide layer is formed on the surface of the heat-treated particles by heat treatment in an oxygen atmosphere. Is estimated to be formed. When the positive electrode composition containing the heat-treated particles thus obtained is used, for example, battery characteristics when used under a high voltage condition of a charging voltage of 4.3 V or more are excellent.
熱処理に供するホウ化チタン粒子の純度は、安全性の観点から、例えば９５重量％以上であり、９８重量％以上が好ましい。またホウ化チタン粒子の平均粒径は、サイクル特性と高温保存特性の観点から、中心粒径として、例えば１μｍ以上４μｍ以下であり、２．５μｍ以上３．５μｍ以下が好ましい。 From the viewpoint of safety, the purity of the titanium boride particles subjected to the heat treatment is, for example, 95% by weight or more, and preferably 98% by weight or more. The average particle size of the titanium boride particles is, for example, 1 μm or more and 4 μm or less, and preferably 2.5 μm or more and 3.5 μm or less as the center particle size from the viewpoint of cycle characteristics and high temperature storage characteristics.
酸素含有雰囲気における酸素含有率は、例えば１０体積％以上であり、２０体積％以上が好ましい。生産性の観点から、酸素含有雰囲気は酸素以外の気体を含んでいてもよい。酸素以外の気体としては、例えば、窒素、アルゴン等の不活性ガスを挙げることができる。酸素含有雰囲気は、生産性の観点から、大気雰囲気であることが好ましい。 The oxygen content in the oxygen-containing atmosphere is, for example, 10% by volume or more, and preferably 20% by volume or more. From the viewpoint of productivity, the oxygen-containing atmosphere may contain a gas other than oxygen. Examples of gases other than oxygen include inert gases such as nitrogen and argon. The oxygen-containing atmosphere is preferably an air atmosphere from the viewpoint of productivity.
熱処理温度は、充放電特性の観点から、１５０℃以上であり、１８０℃以上が好ましく、２００℃以上がより好ましい。また熱処理温度は、高温保存特性およびサイクル特性の観点から、３００℃以下であり、２８０℃以下が好ましく、２５０℃以下がより好ましい。熱処理時間は、得られるホウ化チタン粒子の酸素含有率が、例えば１．６重量％以上１．８重量％以下となるように設定すればよく、例えば、５時間以上１５時間以下である。
ホウ化チタン粒子の熱処理は、例えばボックス炉を用いて行われる。
From the viewpoint of charge / discharge characteristics, the heat treatment temperature is 150 ° C. or higher, preferably 180 ° C. or higher, and more preferably 200 ° C. or higher. Moreover, the heat processing temperature is 300 degrees C or less from a viewpoint of a high temperature storage characteristic and cycling characteristics, 280 degrees C or less is preferable and 250 degrees C or less is more preferable. What is necessary is just to set the heat processing time so that the oxygen content rate of the titanium boride particle | grains obtained may be 1.6 weight% or more and 1.8 weight% or less, for example, is 5 hours or more and 15 hours or less.
The heat treatment of the titanium boride particles is performed using, for example, a box furnace.
熱処理済みのホウ化チタン粒子は、酸素成分を含むことが好ましい。酸素成分の含有率は、充放電特性の観点から、酸素換算で１．５重量％以上であり、１．６重量％以上が好ましく、１．７重量％以上がより好ましい。また酸素成分の含有率は、高温保存特性およびサイクル特性の観点から、例えば２．９重量％以下であり、２．５重量％以下が好ましく、２．０重量％以下がより好ましい。熱処理済み粒子における酸素成分の含有率は、酸素窒素分析装置を用いて測定される。なお、熱処理済み粒子の平均粒径は、熱処理前のホウ化チタン粒子と実質的に同じと考えられる。 The heat-treated titanium boride particles preferably contain an oxygen component. The content of the oxygen component is 1.5% by weight or more in terms of oxygen, preferably 1.6% by weight or more, and more preferably 1.7% by weight or more from the viewpoint of charge / discharge characteristics. The content of the oxygen component is, for example, 2.9% by weight or less, preferably 2.5% by weight or less, and more preferably 2.0% by weight or less from the viewpoint of high temperature storage characteristics and cycle characteristics. The content rate of the oxygen component in the heat-treated particles is measured using an oxygen-nitrogen analyzer. The average particle diameter of the heat-treated particles is considered to be substantially the same as that of the titanium boride particles before the heat treatment.
図１は、得られる正極組成物を用いた非水電解液二次電池における、ホウ化チタンを熱処理する熱処理温度と充放電特性との関係を示すグラフの一例である。ここで充放電特性は、充電電圧４．５Ｖ、放電電圧２．７５Ｖにおける充電容量Ｑｄに対する放電容量Ｑｃの比Ｑｃ／Ｑｄで表される充放電効率Ｐｃｄで評価した。図１から分かるように、熱処理温度が１５０℃辺りを超えると充放電特性が極めて向上する。このため、熱処理温度は１５０℃以上とする。 FIG. 1 is an example of a graph showing the relationship between heat treatment temperature for heat treatment of titanium boride and charge / discharge characteristics in a non-aqueous electrolyte secondary battery using the obtained positive electrode composition. Here, the charge / discharge characteristics were evaluated by the charge / discharge efficiency P cd represented by the ratio Q c / Q d of the discharge capacity Q c to the charge capacity Q d at a charge voltage of 4.5 V and a discharge voltage of 2.75 V. As can be seen from FIG. 1, when the heat treatment temperature exceeds about 150 ° C., the charge / discharge characteristics are remarkably improved. For this reason, heat processing temperature shall be 150 degreeC or more.
図３は、得られる正極組成物を用いた非水電解液二次電池における、ホウ化チタンを熱処理する熱処理温度と高温保存特性との関係を示すグラフの一例である。ここで高温保存特性は、充電電圧４．４Ｖでトリクル充電し続けた前後における放電容量の維持率、すなわち容量維持率Ｐｋで評価した。図３から分かるように、熱処理温度が３００℃を超えた辺りから高温保存特性が悪化しだす傾向にある。そのため、熱処理温度は３００℃以下とする。 FIG. 3 is an example of a graph showing the relationship between the heat treatment temperature for heat treating titanium boride and the high-temperature storage characteristics in a non-aqueous electrolyte secondary battery using the obtained positive electrode composition. Here, the high-temperature storage characteristics were evaluated by the discharge capacity maintenance ratio before and after trickle charging at a charging voltage of 4.4 V, that is, the capacity maintenance ratio Pk . As can be seen from FIG. 3, the high-temperature storage characteristics tend to deteriorate when the heat treatment temperature exceeds 300 ° C. Therefore, the heat treatment temperature is set to 300 ° C. or lower.
図４は、得られる正極組成物を用いた非水電解液二次電池における、ホウ化チタンを熱処理する熱処理温度と別の高温保存特性との関係を示すグラフの一例である。ここで高温保存特性は、充電電圧４．４Ｖでのトリクル充電、放電電圧２．７５Ｖでの放電および４．４Ｖでの充電を行った前後における充電容量の維持率、すなわち復帰率Ｐｒで評価した。図４から分かるように、別の高温保存特性もまた、熱処理温度が３００℃を超えた辺りから悪化しだす傾向にある。 FIG. 4 is an example of a graph showing the relationship between the heat treatment temperature for heat treating titanium boride and another high temperature storage characteristic in a non-aqueous electrolyte secondary battery using the obtained positive electrode composition. Here, the high-temperature storage characteristics are evaluated by a charge capacity maintenance rate before and after performing trickle charging at a charging voltage of 4.4V, discharging at a discharging voltage of 2.75V, and charging at 4.4V, that is, a recovery rate Pr . did. As can be seen from FIG. 4, the other high temperature storage characteristics also tend to begin to deteriorate when the heat treatment temperature exceeds 300 ° C.
図６は、得られる正極組成物を用いた非水電解液二次電池における、ホウ化チタンを熱処理する熱処理温度とサイクル特性との関係を示すグラフの一例である。ここでサイクル特性は、充電電圧４．４Ｖでの充電と放電電圧２．７５Ｖでの放電とを１００回繰り返した前後における放電容量の維持率、すなわち１００サイクル後の容量維持率Ｐｃｙｃで評価した。図６から分かるように、サイクル特性もまた、熱処理温度が３００℃を超えた辺りから悪化しだす傾向にある。 FIG. 6 is an example of a graph showing the relationship between the heat treatment temperature for heat treatment of titanium boride and the cycle characteristics in a non-aqueous electrolyte secondary battery using the obtained positive electrode composition. Here, the cycle characteristics were evaluated by the discharge capacity retention ratio before and after repeating charging at a charging voltage of 4.4 V and discharging at a discharge voltage of 2.75 V, that is, the capacity retention ratio P cyc after 100 cycles. . As can be seen from FIG. 6, the cycle characteristics also tend to deteriorate when the heat treatment temperature exceeds 300 ° C.
＜正極組成物を得る工程＞
正極組成物を得る工程では、得られた熱処理済み粒子と特定の正極活物質とを特定の比率で混合し、目的の非水系二次電池用正極組成物を得る。
<Step of obtaining a positive electrode composition>
In the step of obtaining a positive electrode composition, the obtained heat-treated particles and a specific positive electrode active material are mixed in a specific ratio to obtain a target positive electrode composition for a non-aqueous secondary battery.
［正極活物質］
正極活物質は、遷移金属としてニッケルを含有した層状構造を有するリチウム遷移金属複合酸化物を主成分に用いる。正極活物質は、主成分として用いられるリチウム遷移金属複合酸化物粒子からなることが好ましいが、リチウムイオンを脱離および吸着可能な他のリチウム遷移金属複合酸化物が含まれていてもよい。他のリチウム遷移金属複合酸化物としては、例えばリチウムコバルト複合酸化物、スピネル構造のリチウムマンガン複合酸化物、オリビン構造のリン酸鉄リチウム等を挙げることができる。正極活物質に含まれるニッケルを含み層状構造を有するリチウム遷移金属複合酸化物の含有率は、例えば９０重量％以上であり、９５重量％以上が好ましい。正極活物質が他のリチウム遷移金属複合酸化物を含む場合、その含有率は、例えば１０重量％以下であり、５重量％以下が好ましい。
[Positive electrode active material]
As the positive electrode active material, a lithium transition metal composite oxide having a layered structure containing nickel as a transition metal is used as a main component. The positive electrode active material is preferably composed of lithium transition metal composite oxide particles used as a main component, but may contain other lithium transition metal composite oxides capable of desorbing and adsorbing lithium ions. Examples of other lithium transition metal composite oxides include lithium cobalt composite oxide, spinel-structure lithium manganese composite oxide, and olivine-structure lithium iron phosphate. The content of the lithium transition metal composite oxide containing nickel and having a layered structure contained in the positive electrode active material is, for example, 90% by weight or more, and preferably 95% by weight or more. When the positive electrode active material contains another lithium transition metal composite oxide, the content is, for example, 10% by weight or less, and preferably 5% by weight or less.
主成分として用いられる組成にニッケルを含み層状構造を有するリチウム遷移金属複合酸化物粒子は、例えば組成式ＬｉａＮｉ１−ｘ−ｙ−ｚＣｏｘＭｎｙＭ１ ｚＭ２ ｗＯ２（１．００≦ａ≦１．５０、０．００≦ｘ≦０．５０、０．００≦ｙ≦０．５０、０．００≦ｚ≦０．１５、０．０００≦ｗ≦０．０２０、ｘ＋ｙ＋ｚ≦０．７０、Ｍ１はＡｌおよびＭｇからなる群より選択される少なくとも一種の元素、Ｍ２はＴｉ、Ｚｒ、Ｗ、Ｔａ、ＮｂおよびＭｏからなる群より選択される少なくとも一種の元素）で表される。 Lithium transition metal composite oxide particles having a layered structure comprising nickel on the composition used as a main component, for example, the composition formula Li a Ni 1-x-y -z Co x Mn y M 1 z M 2 w O 2 (1 0.00 ≦ a ≦ 1.50, 0.00 ≦ x ≦ 0.50, 0.00 ≦ y ≦ 0.50, 0.00 ≦ z ≦ 0.15, 0.000 ≦ w ≦ 0.020, x + y + z ≦ 0.70, M 1 is at least one element selected from the group consisting of Al and Mg, and M 2 is at least one element selected from the group consisting of Ti, Zr, W, Ta, Nb and Mo) expressed.
リチウム遷移金属複合酸化物粒子（以下主成分とも呼ぶ）において、リチウムの量が多いと出力特性が向上する傾向にあるが、合成が困難になる傾向がある。このことを踏まえ、主成分の組成式におけるａ値の範囲は１．００≦ａ≦１．５０とする。好ましいａ値の範囲は１．０５≦ａ≦１．２５であり、より好ましくは１．０５≦ａ≦１．１５である。 In a lithium transition metal composite oxide particle (hereinafter also referred to as a main component), if the amount of lithium is large, output characteristics tend to be improved, but synthesis tends to be difficult. Based on this, the range of the a value in the composition formula of the main component is 1.00 ≦ a ≦ 1.50. A preferable range of the a value is 1.05 ≦ a ≦ 1.25, and more preferably 1.05 ≦ a ≦ 1.15.
主成分は遷移金属としてニッケルを含む。ニッケルを含むことによって、例えばリチウムコバルト複合酸化物以上の充放電容量を実現することができる。 The main component contains nickel as a transition metal. By including nickel, for example, a charge / discharge capacity higher than that of the lithium cobalt composite oxide can be realized.
主成分におけるニッケルの一部はコバルトによって置換されていてもよい。コバルトによるニッケルの置換量は、本開示が解決しようとする課題以外の目的に応じて適宜決めて良い。但し、コバルトが多くなると製造コストが増大する。このことを踏まえ、主成分の組成式におけるｘ値の範囲は０．００≦ｘ≦０．５０とする。各種特性とコストとのバランスを考慮すると、好ましいｘ値の範囲は０．０５≦ｘ≦０．３５であり、より好ましくは０．１≦ｘ≦０．３であり、更に好ましくは０．１５≦ｘ≦０．２５である。 A part of nickel in the main component may be substituted with cobalt. The amount of nickel replaced by cobalt may be determined as appropriate according to purposes other than the problems to be solved by the present disclosure. However, the production cost increases when the amount of cobalt increases. Based on this, the range of the x value in the composition formula of the main component is set to 0.00 ≦ x ≦ 0.50. Considering the balance between various characteristics and cost, the preferable range of x value is 0.05 ≦ x ≦ 0.35, more preferably 0.1 ≦ x ≦ 0.3, and still more preferably 0.15. ≦ x ≦ 0.25.
主成分におけるニッケルの一部はマンガンによって置換されていてもよい。マンガンによるニッケルの置換量は、本開示が解決しようとする課題以外の目的に応じて適宜決めて良い。但し、マンガンが多くなると放電容量が低下する。このことを踏まえ、主成分の組成式におけるｙ値の範囲は０．００≦ｙ≦０．５０とする。各種特性のバランスを考慮すると、好ましいｙ値の範囲は０．１０≦ｙ≦０．４０であり、より好ましくは０．２０≦ｙ≦０．４０であり、更に好ましくは０．２５≦ｙ≦０．３５である。 A part of nickel in the main component may be substituted with manganese. The amount of substitution of nickel by manganese may be appropriately determined according to purposes other than the problem to be solved by the present disclosure. However, the discharge capacity decreases as the amount of manganese increases. Based on this, the range of the y value in the composition formula of the main component is set to 0.00 ≦ y ≦ 0.50. Considering the balance of various characteristics, the preferred y value range is 0.10 ≦ y ≦ 0.40, more preferably 0.20 ≦ y ≦ 0.40, and still more preferably 0.25 ≦ y ≦ 0.40. 0.35.
主成分におけるニッケルの一部はアルミニウムおよびマグネシウムからなる群より選択される少なくとも一種の元素Ｍ１によって置換されていてもよい。元素Ｍ１によるニッケルの置換量は、本開示が解決しようとする課題以外の目的に応じて適宜決めて良い。但し、元素Ｍ１は典型元素であり電気化学反応への寄与が少ないので、元素Ｍ１によるニッケルの置換量はあまり多くない方が好ましい。このことを踏まえ、主成分の組成式におけるｚ値の範囲は０．００≦ｚ≦０．３０とする。各種特性のバランスを考慮すると、好ましいｚ値の範囲は０．００≦ｚ≦０．１５である。 A part of nickel in the main component may be substituted with at least one element M 1 selected from the group consisting of aluminum and magnesium. Substitution of nickel by elemental M 1 may appropriately determined depending on the purpose other than object of the present disclosure is to solve. However, since the element M 1 is a typical element and does not contribute much to the electrochemical reaction, it is preferable that the amount of substitution of nickel by the element M 1 is not so large. Based on this, the range of the z value in the composition formula of the main component is set to 0.00 ≦ z ≦ 0.30. In consideration of the balance of various characteristics, a preferable z value range is 0.00 ≦ z ≦ 0.15.
主成分にはさらにチタン、ジルコニウム、タングステン、タンタル、ニオブおよびモリブデンからなる群より選択される少なくとも一種の元素Ｍ２を含有させることができる。元素Ｍ２によるニッケルの置換量は、本開示が解決しようとする課題以外の目的に応じて適宜決めて良い。但し、元素Ｍ２は主成分の結晶構造を大きく歪ませ得るのでその含有量はあまり多くないことが好ましい。このことを踏まえ、主成分の組成式におけるｗ値の範囲は０．０００≦ｗ≦０．０５０とする。各種特性のバランスを考慮すると、好ましいｗ値の範囲は０．０００≦ｗ≦０．０２０である。 May further contain titanium, zirconium, tungsten, tantalum, an element M 2 of the at least one selected from the group consisting of niobium and molybdenum as a main component. The amount of replacement of nickel by the element M 2 may be appropriately determined according to purposes other than the problem to be solved by the present disclosure. However, the content thereof since the element M 2 may distort increasing the crystal structure of the main component is preferably not too much. Based on this, the range of the w value in the composition formula of the main component is 0.000 ≦ w ≦ 0.050. In consideration of the balance of various characteristics, a preferable range of w value is 0.000 ≦ w ≦ 0.020.
主成分がリチウムニッケル系複合酸化物としての利点を有するように、主成分におけるニッケルの総置換量は一定範囲内に収まらせる。主成分の組成式においてｘ＋ｙ＋ｚ≦０．７０であれば、主成分がリチウムニッケル系複合酸化物としての利点を有する。各種特性のバランスを考慮すると、０．２０≦ｘ＋ｙ＋ｚ≦０．６０であることが好ましく、０．４０≦ｘ＋ｙ＋ｚ≦０．６０であることがより好ましい。 The total substitution amount of nickel in the main component is kept within a certain range so that the main component has an advantage as the lithium nickel composite oxide. If x + y + z ≦ 0.70 in the composition formula of the main component, the main component has an advantage as a lithium nickel composite oxide. Considering the balance of various characteristics, 0.20 ≦ x + y + z ≦ 0.60 is preferable, and 0.40 ≦ x + y + z ≦ 0.60 is more preferable.
リチウム遷移金属複合酸化物粒子の平均粒径は、活物質層の充填性の観点から、中心粒径として例えば３μｍ以上３０μｍ以下であり、５μｍ以上２０μｍ以下が好ましい。リチウム遷移金属複合酸化物粒子の平均粒径のホウ化チタン粒子の平均粒径に対する比は、混合時の均一性の観点から、例えば０．７５以上３０以下であり、１以上１０以下が好ましい。 The average particle diameter of the lithium transition metal composite oxide particles is, for example, 3 μm or more and 30 μm or less, and preferably 5 μm or more and 20 μm or less, as the center particle diameter, from the viewpoint of the fillability of the active material layer. The ratio of the average particle diameter of the lithium transition metal composite oxide particles to the average particle diameter of the titanium boride particles is, for example, from 0.75 to 30 and preferably from 1 to 10 from the viewpoint of uniformity during mixing.
［混合比率］
熱処理済み粒子のリチウム遷移金属複合酸化物粒子に対する含有率は、充放電特性の観点から、チタン換算で１．５ｍｏｌ％以下であり、１．２ｍｏｌ％以下が好ましく、１．０ｍｏｌ％以下がより好ましい。また熱処理済み粒子のリチウム遷移金属複合酸化物粒子に対する含有率は、高温保存特性およびサイクル特性の観点から、チタン換算で０．３ｍｏｌ％以上であり、０．４ｍｏｌ％以上が好ましく、０．５ｍｏｌ％以上がより好ましい。
[Mixing ratio]
The content of the heat-treated particles with respect to the lithium transition metal composite oxide particles is 1.5 mol% or less, preferably 1.2 mol% or less, more preferably 1.0 mol% or less in terms of titanium, from the viewpoint of charge / discharge characteristics. . The content of the heat-treated particles with respect to the lithium transition metal composite oxide particles is 0.3 mol% or more, preferably 0.4 mol% or more, preferably 0.5 mol% in terms of titanium from the viewpoint of high-temperature storage characteristics and cycle characteristics. The above is more preferable.
図２は、得られる正極組成物を用いた非水電解液二次電池における、熱処理済み粒子の含有率と充放電特性との関係を示すグラフである。ここで熱処理済み粒子の含有率は、主成分に対するチタンとしての含有率で定義する。図２から分かるように、熱処理済み粒子の含有率が１．５ｍｏｌ％を超えた辺りから充放電特性が悪化しだす傾向にある。そのため、熱処理済み粒子は、主成分に対してチタンとして１．５ｍｏｌ％以下となるよう正極活物質と混合する。 FIG. 2 is a graph showing the relationship between the content of heat-treated particles and charge / discharge characteristics in a non-aqueous electrolyte secondary battery using the obtained positive electrode composition. Here, the content rate of the heat-treated particles is defined by the content rate as titanium with respect to the main component. As can be seen from FIG. 2, the charge / discharge characteristics tend to deteriorate when the content of the heat-treated particles exceeds 1.5 mol%. Therefore, the heat-treated particles are mixed with the positive electrode active material so as to be 1.5 mol% or less as titanium with respect to the main component.
図５は、得られる正極組成物を用いた非水電解液二次電池における、熱処理済み粒子の含有率と別の高温保存特性との関係を示すグラフである。図５から分かるように、熱処理済み粒子の含有率が０．３ｍｏｌ％辺りを超えると別の高温保存特性が極めて向上する傾向にある。そのため、熱処理済み粒子は、主成分に対してチタンとして０．３ｍｏｌ％以上となるよう正極活物質と混合することが好ましい。 FIG. 5 is a graph showing the relationship between the content of heat-treated particles and another high-temperature storage characteristic in a non-aqueous electrolyte secondary battery using the obtained positive electrode composition. As can be seen from FIG. 5, when the content of the heat-treated particles exceeds about 0.3 mol%, another high temperature storage characteristic tends to be extremely improved. Therefore, it is preferable to mix the heat-treated particles with the positive electrode active material so that the titanium content is 0.3 mol% or more with respect to the main component.
図７は、得られる正極組成物を用いた非水電解液二次電池における、熱処理済み粒子の含有率とサイクル特性との関係を示すグラフである。図７から分かるように、サイクル特性もまた、熱処理済み粒子の含有率が０．３ｍｏｌ％辺りを超えると極めて向上する傾向いある。 FIG. 7 is a graph showing the relationship between the content ratio of heat-treated particles and cycle characteristics in a non-aqueous electrolyte secondary battery using the obtained positive electrode composition. As can be seen from FIG. 7, the cycle characteristics also tend to be greatly improved when the content of the heat-treated particles exceeds about 0.3 mol%.
［混合方法］
混合方法は、熱処理済み粒子および正極活物質が化学変化を起こさない程度に強い力で行う方法であれば、その方法は特に限定されない。例えば公知の羽根式撹拌装置で熱処理済み粒子と正極活物質とを混合する方法が挙げられる。
[Mixing method]
The mixing method is not particularly limited as long as the heat-treated particles and the positive electrode active material are subjected to a force strong enough not to cause a chemical change. For example, there is a method of mixing the heat-treated particles and the positive electrode active material with a known blade type stirring device.
本実施形態の製造方法では、熱処理済み粒子と正極活物質とを混合して正極組成物を得る。混合は、熱処理済み粒子と正極活物質とが、機械的または熱的エネルギー等の付与により化学的に反応したり、物理的に変化したりすることが抑制されて行われる。これにより得られる正極組成物には、熱処理済み粒子と、正極活物質を構成するリチウム遷移金属複合酸化物粒子とが、それぞれ実質的に独立した粒子として含まれると考えられる。ここで実質的に独立した粒子として含まれるとは、例えば、熱処理済み粒子とリチウム遷移金属複合酸化物粒子とが融合していたり、焼結して一体化していたりすることが観察されないことを意味する。具体的には例えば、熱処理済み粒子の平均粒径とリチウム遷移金属複合酸化物粒子の平均粒径とが相違する場合には、正極組成物の粒度分布において、熱処理済み粒子に由来するピークとリチウム遷移金属複合酸化物粒子に由来するピークとが観察できることを意味する。また、例えば走査型電子顕微鏡−エネルギー分散型Ｘ線分光分析装置を用いて、元素マッピングをすることで、熱処理済み粒子とリチウム遷移金属複合酸化物粒子とが実質的に独立した粒子として含まれることを観察することができる。 In the manufacturing method of this embodiment, the heat-treated particles and the positive electrode active material are mixed to obtain a positive electrode composition. The mixing is performed while the heat-treated particles and the positive electrode active material are suppressed from chemically reacting or physically changing due to application of mechanical or thermal energy or the like. It is considered that the positive electrode composition obtained in this way contains the heat-treated particles and the lithium transition metal composite oxide particles constituting the positive electrode active material as substantially independent particles. Here, being included as substantially independent particles means, for example, that heat-treated particles and lithium transition metal composite oxide particles are not observed to be fused or sintered and integrated. To do. Specifically, for example, when the average particle size of the heat-treated particles and the average particle size of the lithium transition metal composite oxide particles are different, the peak derived from the heat-treated particles and lithium in the particle size distribution of the positive electrode composition This means that a peak derived from the transition metal composite oxide particles can be observed. In addition, for example, by using elemental mapping using a scanning electron microscope-energy dispersive X-ray spectrometer, the heat-treated particles and the lithium transition metal composite oxide particles are included as substantially independent particles. Can be observed.
非水系二次電池用正極組成物
本開示の第二実施形態に係る非水系二次電池用正極組成物は、ホウ化チタン粒子と、組成にニッケルを含み層状構造を有するリチウム遷移金属複合酸化物粒子を含む正極活物質とを含み、ホウ化チタン粒子は酸素成分を含み、その含有率が１．５重量％以上２．９重量％以下であり、ホウ化チタン粒子のリチウム遷移金属複合酸化物粒子に対する含有率が、チタンとして１．５ｍｏｌ％以下である非水系二次電池用正極組成物である。非水系二次電池用正極組成物を用いて構成される正極を備える非水系二次電池は、高電圧における充放電特性、高温保存特性およびサイクル特性に優れる。
Positive electrode composition for nonaqueous secondary battery A positive electrode composition for a nonaqueous secondary battery according to a second embodiment of the present disclosure includes titanium boride particles and a lithium transition metal composite oxide having a layered structure containing nickel in the composition. A positive electrode active material containing particles, the titanium boride particles contain an oxygen component, and the content thereof is 1.5 wt% or more and 2.9 wt% or less, and the lithium transition metal composite oxide of the titanium boride particles It is the positive electrode composition for non-aqueous secondary batteries whose content rate with respect to particle | grains is 1.5 mol% or less as titanium. A non-aqueous secondary battery including a positive electrode formed using a positive electrode composition for a non-aqueous secondary battery is excellent in charge / discharge characteristics at high voltage, high-temperature storage characteristics, and cycle characteristics.
ホウ化チタン粒子は酸素成分を含み、酸素成分の含有率が酸素換算で１．５重量％以上２．９重量％以下である。酸素成分の含有率は、充放電特性の観点から、１．６重量％以上が好ましく、１．７重量％以上がより好ましい。また酸素成分の含有率は、高温保存特性およびサイクル特性の観点から、２．５重量％以下が好ましく、２．０重量％以下がより好ましく、１．８重量％以下が更に好ましい。ホウ化チタン粒子に含まれる酸素成分が、例えば粒子表面に酸化チタン等として存在することにより、例えば電解液に対するホウ化チタンの溶出速度が適切に制御されるためと考えられる。またホウ化チタン粒子表面の酸化チタン等の存在により、混合時の正極活物質との化学的な反応や、物理的な変化が抑制されていると考えられる。酸素成分を含むホウ化チタン粒子は、市販品であってもよく、酸素含有雰囲気で熱処理して得られたものであってもよい。熱処理して得られたホウ化チタン粒子を用いることで充放電特性がより向上する傾向がある。ホウ化チタン粒子の好ましい態様は既述の通りである。 The titanium boride particles contain an oxygen component, and the content of the oxygen component is 1.5 wt% or more and 2.9 wt% or less in terms of oxygen. The content of the oxygen component is preferably 1.6% by weight or more, and more preferably 1.7% by weight or more from the viewpoint of charge / discharge characteristics. Further, the content of the oxygen component is preferably 2.5% by weight or less, more preferably 2.0% by weight or less, and still more preferably 1.8% by weight or less, from the viewpoints of high temperature storage characteristics and cycle characteristics. It is considered that the oxygen component contained in the titanium boride particles is present as, for example, titanium oxide on the particle surface, so that, for example, the elution rate of titanium boride with respect to the electrolytic solution is appropriately controlled. Further, it is considered that the chemical reaction with the positive electrode active material and the physical change during mixing are suppressed by the presence of titanium oxide or the like on the surface of the titanium boride particles. The titanium boride particles containing an oxygen component may be a commercially available product or may be obtained by heat treatment in an oxygen-containing atmosphere. Charge / discharge characteristics tend to be further improved by using titanium boride particles obtained by heat treatment. Preferred embodiments of the titanium boride particles are as described above.
正極組成物は、正極活物質を含み、正極活物質は組成にニッケルを含み層状構造を有するリチウム遷移金属複合酸化物粒子を少なくとも含む。リチウム遷移金属複合酸化物の詳細については既述の通りである。 The positive electrode composition includes a positive electrode active material, and the positive electrode active material includes at least lithium transition metal composite oxide particles that include nickel in the composition and have a layered structure. Details of the lithium transition metal composite oxide are as described above.
正極組成物におけるホウ化チタン粒子のリチウム遷移金属複合酸化物粒子に対する含有率は、充放電特性の観点から、チタン換算で１．５ｍｏｌ％以下であり、１．２ｍｏｌ％以下が好ましく、１．０ｍｏｌ％以下がより好ましい。またホウ化チタン粒子のリチウム遷移金属複合酸化物粒子に対する含有率は、高温保存特性およびサイクル特性の観点から、チタン換算で０．３ｍｏｌ％以上であり、０．４ｍｏｌ％以上が好ましく、０．５ｍｏｌ％以上がより好ましい。非水系二次電池用正極組成物は、例えば、既述の製造方法によって製造される。 From the viewpoint of charge / discharge characteristics, the content of titanium boride particles in the positive electrode composition with respect to the lithium transition metal composite oxide particles is 1.5 mol% or less, preferably 1.2 mol% or less, preferably 1.0 mol, in terms of titanium. % Or less is more preferable. Further, the content of the titanium boride particles with respect to the lithium transition metal composite oxide particles is 0.3 mol% or more, preferably 0.4 mol% or more, preferably 0.5 mol% in terms of titanium from the viewpoint of high-temperature storage characteristics and cycle characteristics. % Or more is more preferable. The positive electrode composition for non-aqueous secondary batteries is manufactured, for example, by the above-described manufacturing method.
実施例を以下に説明する。なお、リチウム遷移金属複合酸化物粒子およびホウ化チタン粒子の中心粒径は、レーザー散乱法によって得られる体積分布の、積算値が５０％となる値を用いた。具体的には日本新金属株式会社製ＴＩＢ２-ＮＦを用いて中心粒径を測定した。またホウ化チタン粒子の酸素成分の含有率（酸素含有率）は、酸素窒素分析装置（堀場製作所製ＥＭＧＡ−８２０）を用いて測定した。 Examples will be described below. The center particle diameter of the lithium transition metal composite oxide particles and the titanium boride particles was a value at which the integrated value of the volume distribution obtained by the laser scattering method was 50%. Specifically, the center particle size was measured using TIB2-NF manufactured by Nippon Shin Metals Co., Ltd. Moreover, the content rate (oxygen content rate) of the oxygen component of the titanium boride particles was measured using an oxygen nitrogen analyzer (EMGA-820 manufactured by Horiba, Ltd.).
［実施例１］
中心粒径が２．９μｍのホウ化チタン粒子を、大気中２５０℃で１０時間熱処理し、熱処理済み粒子を得た。熱処理済み粒子の酸素含有率は、１．８重量％であった。
[Example 1]
Titanium boride particles having a center particle size of 2.9 μm were heat-treated at 250 ° C. for 10 hours in the atmosphere to obtain heat-treated particles. The oxygen content of the heat-treated particles was 1.8% by weight.
共沈法により、（Ｎｉ０．５Ｃｏ０．２Ｍｎ０．３）（ＯＨ）ｘ（ｘ＝２〜３）で表される複合水酸化物を得た。得られた複合水酸化物と、炭酸リチウムとを、Ｌｉ：（Ｎｉ＋Ｃｏ＋Ｍｎ）＝１．０８：１のモル比となるように混合し、原料混合物を得た。得られた原料混合物を大気雰囲気下、８５０℃で２．５時間焼成し、引き続き９６０℃で８時間焼成し、焼結体を得た。得られた焼結体を粉砕し、乾式篩を通し、組成式Ｌｉ１．０８Ｎｉ０．５Ｃｏ０．２Ｍｎ０．３Ｏ２で表され、中心粒径が１７μｍであるリチウム遷移金属複合酸化物粒子を含む、正極活物質を得た。 A composite hydroxide represented by (Ni 0.5 Co 0.2 Mn 0.3 ) (OH) x (x = 2 to 3) was obtained by a coprecipitation method. The obtained composite hydroxide and lithium carbonate were mixed at a molar ratio of Li: (Ni + Co + Mn) = 1.08: 1 to obtain a raw material mixture. The obtained raw material mixture was baked at 850 ° C. for 2.5 hours in an air atmosphere, and subsequently baked at 960 ° C. for 8 hours to obtain a sintered body. The obtained sintered body is pulverized, passed through a dry sieve, a lithium transition metal composite having a composition formula of Li 1.08 Ni 0.5 Co 0.2 Mn 0.3 O 2 and a center particle size of 17 μm. A positive electrode active material containing oxide particles was obtained.
得られた熱処理済み粒子と、得られた正極活物質とを、熱処理済み粒子がリチウム遷移金属複合酸化物に対してチタンとして１．０ｍｏｌ％となるよう高速せん断ミキサーで混合し、目的の非水系二次電池用正極組成物を得た。 The obtained heat-treated particles and the obtained positive electrode active material are mixed with a high-speed shear mixer so that the heat-treated particles are 1.0 mol% as titanium with respect to the lithium transition metal composite oxide, and the desired non-aqueous system A positive electrode composition for a secondary battery was obtained.
［実施例２］
熱処理済み粒子の含有率が、リチウム遷移金属複合酸化物に対してチタンとして１．５ｍｏｌ％であること以外実施例１と同様に行い、目的の非水系二次電池用正極組成物を得た。
[Example 2]
The same procedure as in Example 1 was conducted except that the content of the heat-treated particles was 1.5 mol% as titanium with respect to the lithium transition metal composite oxide, to obtain the intended positive electrode composition for non-aqueous secondary batteries.
［実施例３］
中心粒径が２．９μｍのホウ化チタン粒子を、大気中１５０℃で１０時間熱処理し、熱処理済み粒子を得た。熱処理済み粒子の酸素含有率は、１．５重量％であった。
[Example 3]
Titanium boride particles having a center particle diameter of 2.9 μm were heat-treated at 150 ° C. for 10 hours in the atmosphere to obtain heat-treated particles. The oxygen content of the heat-treated particles was 1.5% by weight.
実施例１と同様にして組成式Ｌｉ１．０８Ｎｉ０．５Ｃｏ０．２Ｍｎ０．３Ｏ２で表され、中心粒径が１７μｍであるリチウム遷移金属複合酸化物粒子を含む、正極活物質を得た。 A positive electrode active material comprising lithium transition metal composite oxide particles represented by the composition formula Li 1.08 Ni 0.5 Co 0.2 Mn 0.3 O 2 and having a center particle size of 17 μm in the same manner as in Example 1. Obtained material.
得られた熱処理済み粒子と、得られた正極活物質とを、熱処理済み粒子の含有率が、リチウム遷移金属複合酸化物に対してチタンとして０．５ｍｏｌ％となるよう高速せん断ミキサーで混合し、目的の非水系二次電池用正極組成物を得た。 The obtained heat-treated particles and the obtained positive electrode active material are mixed with a high-speed shear mixer so that the content of the heat-treated particles is 0.5 mol% as titanium with respect to the lithium transition metal composite oxide, The objective positive electrode composition for non-aqueous secondary batteries was obtained.
［実施例４］
ホウ化チタン粒子の熱処理温度が２００℃であること以外実施例３と同様に行い、目的の非水系二次電池用正極組成物を得た。熱処理済みのホウ化チタン粒子の酸素含有率は、１．６重量％であった。
[Example 4]
The same procedure as in Example 3 was conducted except that the heat treatment temperature of the titanium boride particles was 200 ° C., to obtain the target positive electrode composition for non-aqueous secondary batteries. The oxygen content of the heat-treated titanium boride particles was 1.6% by weight.
［実施例５］
ホウ化チタン粒子の熱処理温度が２５０℃であること以外実施例３と同様に行い、目的の非水系二次電池用正極組成物を得た。熱処理済みのホウ化チタン粒子の酸素含有率は、１．８重量％であった。
[Example 5]
The same procedure as in Example 3 was conducted except that the heat treatment temperature of the titanium boride particles was 250 ° C., to obtain the target positive electrode composition for non-aqueous secondary batteries. The oxygen content of the heat-treated titanium boride particles was 1.8% by weight.
［実施例６］
ホウ化チタン粒子の熱処理温度が３００℃であること以外実施例３と同様に行い、目的の非水系二次電池用正極組成物を得た。熱処理済みのホウ化チタン粒子の酸素含有率は、２．３重量％であった。
[Example 6]
The same procedure as in Example 3 was conducted except that the heat treatment temperature of the titanium boride particles was 300 ° C., to obtain the target positive electrode composition for non-aqueous secondary batteries. The oxygen content of the heat treated titanium boride particles was 2.3% by weight.
［比較例１］
ホウ化チタン粒子の熱処理を行わなかったこと以外実施例３と同様に行い、目的の非水系二次電池用正極組成物を得た。ホウ化チタン粒子の酸素含有率は、１．４重量％であった。
[Comparative Example 1]
The same procedure as in Example 3 was conducted except that the titanium boride particles were not heat-treated to obtain a target non-aqueous secondary battery positive electrode composition. The oxygen content of the titanium boride particles was 1.4% by weight.
［比較例２］
ホウ化チタン粒子の熱処理温度が３５０℃であること以外実施例３と同様に行い、目的の非水系二次電池用正極組成物を得た。熱処理済みのホウ化チタン粒子の酸素含有率は、３．０重量％であった。
[Comparative Example 2]
The same procedure as in Example 3 was performed except that the heat treatment temperature of the titanium boride particles was 350 ° C., and the target positive electrode composition for non-aqueous secondary batteries was obtained. The oxygen content of the heat-treated titanium boride particles was 3.0% by weight.
［比較例３］
ホウ化チタン粒子の熱処理温度が４００℃であること以外実施例３と同様に行い、目的の非水系二次電池用正極組成物を得た。熱処理済みのホウ化チタン粒子の酸素含有率は、１３．１重量％であった。
[Comparative Example 3]
The same procedure as in Example 3 was performed except that the heat treatment temperature of the titanium boride particles was 400 ° C., to obtain the target positive electrode composition for nonaqueous secondary batteries. The oxygen content of the heat-treated titanium boride particles was 13.1% by weight.
［比較例４］
熱処理済み粒子の含有率が、リチウム遷移金属複合酸化物に対してチタンとして２．０ｍｏｌ％であること以外実施例１と同様に行い、目的の非水系二次電池用正極組成物を得た。
[Comparative Example 4]
The same procedure as in Example 1 was conducted except that the content of the heat-treated particles was 2.0 mol% as titanium with respect to the lithium transition metal composite oxide, to obtain the target positive electrode composition for non-aqueous secondary batteries.
［比較例５］
実施例１における正極活物質を目的の非水系二次電池用正極組成物とした。
[Comparative Example 5]
The positive electrode active material in Example 1 was used as the target positive electrode composition for a non-aqueous secondary battery.
＜評価用電池の作製＞
実施例１〜６および比較例１〜５の正極組成物をそれぞれ用い、以下の要領で評価用の非水電解液二次電池を得た。
<Production of evaluation battery>
Using the positive electrode compositions of Examples 1 to 6 and Comparative Examples 1 to 5, respectively, non-aqueous electrolyte secondary batteries for evaluation were obtained in the following manner.
［正極の作製］
正極組成物８５質量部、アセチレンブラック１０質量部、ポリフッ化ビニリデン５質量部をＮ−メチルピロリドンに分散させて正極スラリーを得た。得られた正極スラリーをアルミニウム箔からなる集電体に塗布し、乾燥後ロールプレス機で圧縮成形し、所定サイズに裁断して正極を得た。
[Production of positive electrode]
A positive electrode slurry was obtained by dispersing 85 parts by mass of the positive electrode composition, 10 parts by mass of acetylene black, and 5 parts by mass of polyvinylidene fluoride in N-methylpyrrolidone. The obtained positive electrode slurry was applied to a current collector made of aluminum foil, dried, compression-molded with a roll press, and cut into a predetermined size to obtain a positive electrode.
［負極の作製］
人造黒鉛９７．５質量部、カルボキシメチルセルロース１．５質量部、スチレンブタジエンゴム１．０質量部を水に分散させて負極スラリーを得た。得られた負極スラリーを銅箔からなる集電体に塗布し、乾燥後ロールプレス機で圧縮成形し、所定サイズに裁断して負極を得た。
[Production of negative electrode]
97.5 parts by mass of artificial graphite, 1.5 parts by mass of carboxymethyl cellulose, and 1.0 part by mass of styrene butadiene rubber were dispersed in water to obtain a negative electrode slurry. The obtained negative electrode slurry was applied to a current collector made of copper foil, dried, compression-molded with a roll press, and cut into a predetermined size to obtain a negative electrode.
［非水電解液の作製］
エチルカーボネートとメチルエチルカーボネートを体積比３：７で混合し、混合溶媒を得た。得られた混合溶媒に、ヘキサフルオロリン酸リチウムを、その濃度が１．０ｍｏｌ％となるように溶解させ、非水電解液を得た。
[Preparation of non-aqueous electrolyte]
Ethyl carbonate and methyl ethyl carbonate were mixed at a volume ratio of 3: 7 to obtain a mixed solvent. Lithium hexafluorophosphate was dissolved in the obtained mixed solvent so that the concentration thereof was 1.0 mol% to obtain a nonaqueous electrolytic solution.
［セパレータの準備］
多孔性ポリエチレンからなるセパレータを準備した。
[Preparation of separator]
A separator made of porous polyethylene was prepared.
［非水電解液二次電池の組み立て］
上記正極と負極の集電体に、それぞれリード電極を取り付けたのち１２０℃で真空乾燥を行った。次いで、正極と負極との間に上記セパレータを配し、袋状のラミネートパックにそれらを収納した。収納後６０℃で真空乾燥して各部材に吸着した水分を除去した。真空乾燥後、ラミネートパック内に、上記非水電解液を注入、封止し、評価用電池としてのラミネートタイプの非水電解液二次電池を得た。得られた評価用電池を用い、以下の電池特性の評価を行った。
[Assembly of non-aqueous electrolyte secondary battery]
After the lead electrodes were attached to the positive and negative electrode current collectors, vacuum drying was performed at 120 ° C. Next, the separator was disposed between the positive electrode and the negative electrode, and they were stored in a bag-shaped laminate pack. After storage, the moisture adsorbed on each member was removed by vacuum drying at 60 ° C. After vacuum drying, the non-aqueous electrolyte was poured into a laminate pack and sealed to obtain a laminate-type non-aqueous electrolyte secondary battery as an evaluation battery. Using the obtained evaluation battery, the following battery characteristics were evaluated.
＜充放電特性の評価＞
充電電圧４．５Ｖ、充電電流０．５Ｃ（１Ｃは満充電状態から１時間で放電を終了させられる電流値）で定電流定電圧充電を行い、充電容量Ｑｃを測定した。次に、放電電圧２．７５Ｖ，放電電流０．５Ｃで定電流放電を行い、放電容量Ｑｄを測定した。得られたＱｃおよびＱｄから、充放電効率Ｐｃｄ（＝Ｑｄ／Ｑｃ）を算出した。
<Evaluation of charge / discharge characteristics>
Constant current and constant voltage charging was performed at a charging voltage of 4.5 V and a charging current of 0.5 C (1 C is a current value at which discharging can be completed in one hour from a fully charged state), and a charging capacity Qc was measured. Next, constant current discharge was performed at a discharge voltage of 2.75 V and a discharge current of 0.5 C, and the discharge capacity Qd was measured. From the obtained Q c and Q d , the charge / discharge efficiency P cd (= Q d / Q c ) was calculated.
＜高温保存特性の評価＞
充電電圧４．４Ｖで定電圧充電を行った後、放電電圧２．７５Ｖで定電圧放電を行い、放電容量Ｑｄ（０）を測定した。次に、充電電圧４．４Ｖで定電圧充電を行い、充電容量Ｑｃ（１）を測定した。充電後、評価用電池を６０℃の恒温槽に設置し、充電電圧４．４Ｖのトリクル充電を７２時間行った。トリクル充電後、放電電圧２．７５Ｖで定電圧放電を行い、放電容量Ｑｄ（１）を測定した。放電後、充電電圧４．４Ｖで定電圧充電を行い、充電容量Ｑｃ（２）を測定した。得られたＱｄ（０）およびＱｄ（１）から、容量維持率Ｐｋ（＝Ｑｄ（１）／Ｑｄ（０））を算出した。また、得られたＱｃ（１）およびＱｃ（２）から復帰率Ｐｒ（＝Ｑｃ（２）／Ｑｃ（１））を算出した。
<Evaluation of high-temperature storage characteristics>
After performing constant voltage charging at a charging voltage of 4.4 V, constant voltage discharging was performed at a discharging voltage of 2.75 V, and the discharge capacity Q d (0) was measured. Next, constant voltage charging was performed at a charging voltage of 4.4 V, and the charging capacity Q c (1) was measured. After charging, the evaluation battery was placed in a constant temperature bath at 60 ° C., and trickle charging at a charging voltage of 4.4 V was performed for 72 hours. After trickle charge, constant voltage discharge was performed at a discharge voltage of 2.75 V, and the discharge capacity Q d (1) was measured. After discharging, constant voltage charging was performed at a charging voltage of 4.4 V, and the charging capacity Q c (2) was measured. From the obtained Q d (0) and Q d (1), the capacity retention rate P k (= Q d (1) / Q d (0)) was calculated. Further, the recovery rate P r (= Q c (2) / Q c (1)) was calculated from the obtained Q c (1) and Q c (2).
＜サイクル特性の評価＞
評価用電池を４５℃の恒温槽に設置し、充電電圧４．４Ｖで定電圧充電を行った。充電後、放電電圧２．７５Ｖで定電圧放電を行い、１サイクル目の放電容量Ｑｄｃｙｃ（１）を測定した。以下充電と放電を繰り返し、最後に１００サイクル目の放電容量Ｑｃｙｃ（１００）を測定した。得られたＱｃｙｃ（１）およびＱｃｙｃ（１００）から１００サイクル後の容量維持率Ｐｃｙｃ（＝Ｑｃｙｃ（１００）／Ｑｃｙｃ（１））を算出した。
<Evaluation of cycle characteristics>
The evaluation battery was placed in a 45 ° C. thermostatic chamber, and constant voltage charging was performed at a charging voltage of 4.4V. After charging, constant voltage discharge was performed at a discharge voltage of 2.75 V, and the discharge capacity Q dcyc (1) at the first cycle was measured. Thereafter, charging and discharging were repeated, and finally, the discharge capacity Q cyc (100) at the 100th cycle was measured. From the obtained Q cyc (1) and Q cyc (100), the capacity retention ratio P cyc after 100 cycles (= Q cyc (100) / Q cyc (1)) was calculated.
実施例１〜６および比較例１〜５の正極組成物の構成を表１に、各正極組成物を用いた評価用電池の各種電池特性を表２に記す。 Table 1 shows the configurations of the positive electrode compositions of Examples 1 to 6 and Comparative Examples 1 to 5, and Table 2 shows various battery characteristics of evaluation batteries using the respective positive electrode compositions.
表１および表２の結果から以下のことが分かる。 The following can be understood from the results of Tables 1 and 2.
熱処理済み粒子を混合せずに得た比較例５の正極組成物を用いた評価用電池は、熱処理済み粒子を混合して得た実施例１〜６の正極組成物を用いた評価用電池に比べ、高温保存特性およびサイクル特性が悪化している。 The evaluation battery using the positive electrode composition of Comparative Example 5 obtained without mixing the heat-treated particles is an evaluation battery using the positive electrode compositions of Examples 1 to 6 obtained by mixing the heat-treated particles. In comparison, the high-temperature storage characteristics and cycle characteristics are deteriorated.
適切な熱処理温度で熱処理をしていない熱処理済み粒子を混合して得た比較例２、３の正極組成物を用いた評価用電池も、適切な熱処理温度で熱処理をした熱処理済み粒子を混合して得た実施例１〜６の正極組成物を用いた評価用電池に比べ、サイクル特性が悪化している。 The battery for evaluation using the positive electrode compositions of Comparative Examples 2 and 3 obtained by mixing heat-treated particles that were not heat-treated at an appropriate heat-treatment temperature was also mixed with heat-treated particles that were heat-treated at an appropriate heat-treatment temperature. Compared with the battery for evaluation using the positive electrode compositions of Examples 1 to 6 obtained as described above, the cycle characteristics were deteriorated.
過剰に熱処理済み粒子を混合して得た比較例４の正極組成物を用いた評価用電池は、適切な熱処理済み粒子を混合して得た実施例１〜６の正極組成物を用いた評価用電池に比べ、高温保存特性の一つである復帰率Ｐｒが悪化している。さらに、サイクル特性が悪化している。 The evaluation battery using the positive electrode composition of Comparative Example 4 obtained by excessively mixing the heat-treated particles was evaluated using the positive electrode compositions of Examples 1 to 6 obtained by mixing appropriate heat-treated particles. compared to use batteries, the return rate P r is deteriorated, which is one of the high-temperature storage characteristics. Further, the cycle characteristics are deteriorated.
ホウ化チタン粒子を熱処理せずに混合して得た比較例１の正極組成物を用いた評価用電池は、熱処理済み粒子を混合して得た実施例１〜６および比較例２〜５の正極組成物を用いた評価用電池に比べ、充放電特性が悪化している。 The batteries for evaluation using the positive electrode composition of Comparative Example 1 obtained by mixing titanium boride particles without heat treatment were those of Examples 1 to 6 and Comparative Examples 2 to 5 obtained by mixing heat-treated particles. Compared with the battery for evaluation using the positive electrode composition, the charge / discharge characteristics are deteriorated.
このため、高電圧における充放電特性、高温保存特性およびサイクル特性の全てを十分にし得る正極組成物を得るには、適切な熱処理温度で熱処理された熱処理済み粒子と、正極活物質とを適切な比率で混合する必要がある。 For this reason, in order to obtain a positive electrode composition capable of sufficiently satisfying all the charge / discharge characteristics, high-temperature storage characteristics, and cycle characteristics at a high voltage, heat-treated particles that have been heat-treated at an appropriate heat treatment temperature and a positive electrode active material are appropriately used. It is necessary to mix in proportions.
本発明の実施形態によって得られる非水系二次電池用正極組成物を用いると、高電圧における充放電特性、高温保存特性およびサイクル特性に優れた非水系二次電池を得ることが可能になる。そのため、得られる非水系二次電池は、電気自動車等の高出力、高エネルギー密度が求められる大型機器に好適に利用可能である。 When the positive electrode composition for a non-aqueous secondary battery obtained by the embodiment of the present invention is used, a non-aqueous secondary battery excellent in charge / discharge characteristics at high voltage, high-temperature storage characteristics and cycle characteristics can be obtained. Therefore, the obtained non-aqueous secondary battery can be suitably used for large equipment such as an electric vehicle that requires high output and high energy density.
Claims (16)
前記熱処理済み粒子と、組成にニッケルを含み層状構造を有するリチウム遷移金属複合酸化物粒子を含む正極活物質とを、前記熱処理済み粒子の前記リチウム遷移金属複合酸化物粒子に対する含有率が、前記熱処理済み粒子中のチタンとして０．３ｍｏｌ％以上１．５ｍｏｌ％以下となるよう混合し、正極組成物を得る工程とを含む、非水系二次電池用正極組成物の製造方法。 Heat treating titanium boride particles in an oxygen-containing atmosphere at a heat treatment temperature of 150 ° C. or more and 300 ° C. or less to obtain heat-treated particles having an oxygen content of 1.5% by weight or more and 2.9% by weight or less ;
The heat-treated particles, and the positive electrode active material containing lithium transition metal composite oxide particles having a layered structure containing nickel in the composition, the content ratio of the heat-treated particles to the lithium transition metal composite oxide particles are the heat treatment A method of producing a positive electrode composition for a non-aqueous secondary battery, including a step of mixing the titanium particles in the finished particles so as to be 0.3 mol% to 1.5 mol% to obtain a positive electrode composition.
ＬｉａＮｉ１−ｘ−ｙ−ｚＣｏｘＭｎｙＭ１ｚＭ２ ｗＯ２ （１）
（１．００≦ａ≦１．５０、０．００≦ｘ≦０．５０、０．００≦ｙ≦０．５０、０．００≦ｚ≦０．１５、０．０００≦ｗ≦０．０２０、ｘ＋ｙ＋ｚ≦０．７０、Ｍ１はＡｌおよびＭｇからなる群より選択される少なくとも一種の元素であり、Ｍ２はＴｉ、Ｚｒ、Ｗ、Ｔａ、ＮｂおよびＭｏからなる群より選択される少なくとも一種の元素である） The manufacturing method of Claim 1 or 2 with which the said lithium transition metal complex oxide has a composition represented by following formula (1).
Li a Ni 1-x-y -z Co x Mn y M 1 zM 2 w O 2 (1)
(1.00 ≦ a ≦ 1.50, 0.00 ≦ x ≦ 0.50, 0.00 ≦ y ≦ 0.50, 0.00 ≦ z ≦ 0.15, 0.000 ≦ w ≦ 0.020 , X + y + z ≦ 0.70, M 1 is at least one element selected from the group consisting of Al and Mg, and M 2 is at least one type selected from the group consisting of Ti, Zr, W, Ta, Nb and Mo Element)
前記ホウ化チタン粒子は酸素成分を含み、その含有率が１．５重量％以上２．９重量％以下であり、
前記ホウ化チタン粒子の前記リチウム遷移金属複合酸化物粒子に対する含有率が、前記ホウ化チタン粒子中のチタンとして０．３ｍｏｌ％以上１．５ｍｏｌ％以下である非水系二次電池用正極組成物。 Including titanium boride particles and a positive electrode active material including lithium transition metal composite oxide particles having a layered structure containing nickel in the composition;
The titanium boride particles contain an oxygen component, and the content thereof is 1.5 wt% or more and 2.9 wt% or less,
The positive electrode composition for a non-aqueous secondary battery, wherein a content ratio of the titanium boride particles to the lithium transition metal composite oxide particles is 0.3 mol% or more and 1.5 mol% or less as titanium in the titanium boride particles .
ＬｉａＮｉ１−ｘ−ｙ−ｚＣｏｘＭｎｙＭ１ ｚＭ２ ｗＯ２ （１）
（１．００≦ａ≦１．５０、０．００≦ｘ≦０．５０、０．００≦ｙ≦０．５０、０．００≦ｚ≦０．１５、０．０００≦ｗ≦０．０２０、ｘ＋ｙ＋ｚ≦０．７０、Ｍ１はＡｌおよびＭｇからなる群より選択される少なくとも一種の元素であり、Ｍ２はＴｉ、Ｚｒ、Ｗ、Ｔａ、ＮｂおよびＭｏからなる群より選択される少なくとも一種の元素である） The positive electrode composition according to claim 9 or 10, wherein the lithium transition metal composite oxide has a composition represented by the following formula (1).
Li a Ni 1-x-y -z Co x Mn y M 1 z M 2 w O 2 (1)
(1.00 ≦ a ≦ 1.50, 0.00 ≦ x ≦ 0.50, 0.00 ≦ y ≦ 0.50, 0.00 ≦ z ≦ 0.15, 0.000 ≦ w ≦ 0.020 , X + y + z ≦ 0.70, M 1 is at least one element selected from the group consisting of Al and Mg, and M 2 is at least one type selected from the group consisting of Ti, Zr, W, Ta, Nb and Mo Element)
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