JP2015038806A - Electrode active material and production method therefor - Google Patents
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Abstract
Description
本発明は、リチウムイオン二次電池等の非水電解液二次電池の電極に用いられる電極活物質に関する。 The present invention relates to an electrode active material used for an electrode of a non-aqueous electrolyte secondary battery such as a lithium ion secondary battery.
リチウムイオン二次電池等の非水電解液二次電池は、高エネルギー密度、高電圧を有し、繰り返しの充放電によるメモリー効果がないことから、携帯電話や、ノート型パソコン、デジタルカメラ、ビデオカメラ等の電子機器類の電源として広く利用されている。非水電解液二次電池の正極板としては、金属薄等の導電体表面に正極活物質層を形成したものが用いられ、負極板としては、銅やアルミニウム等の集電体表面に負極活物質層を形成したものが用いられている。 Non-aqueous electrolyte secondary batteries such as lithium ion secondary batteries have high energy density and high voltage, and have no memory effect due to repeated charge and discharge, so mobile phones, notebook computers, digital cameras, video Widely used as a power source for electronic devices such as cameras. As the positive electrode plate of the non-aqueous electrolyte secondary battery, a metal thin film or the like having a positive electrode active material layer formed on the surface of a conductor is used, and as the negative electrode plate, a negative electrode active material on the surface of a current collector such as copper or aluminum is used. A material layer is used.
正極活物質や負極活物質等の電極活物質としては、例えばマンガン、ニッケル、コバルト、鉄、チタン等の遷移金属酸化物と、ナトリウムやリチウム等のアルカリ金属との複合酸化物等が用いられている。従来より、これらの電極活物質はアルカリ金属化合物と、遷移金属化合物とを焼成する方法で製造され、例えば、マンガン酸化物とリチウム材料との混合物を焼成してＬｉＭｎ２Ｏ４を得る方法（特許文献１）、リチウム炭酸ニッケルや硝酸ニッケル等のニッケル化合物と、硝酸リチウム、炭酸リチウム等のリチウム化合物との混合物を、大気中もしくは酸素雰囲気下で焼成してリチウムとニッケルの複合酸化物を得る方法（特許文献２）、リチウム化合物と遷移金属化合物とを水性媒体中で粉砕した固液混合物を噴霧乾燥して得た粉末固体を、酸素の存在下に焼成して得る方法（特許文献３）等が知られている。 Examples of electrode active materials such as a positive electrode active material and a negative electrode active material include composite oxides of transition metal oxides such as manganese, nickel, cobalt, iron, and titanium and alkali metals such as sodium and lithium. Yes. Conventionally, these electrode active materials are produced by a method of firing an alkali metal compound and a transition metal compound. For example, a method of obtaining a LiMn 2 O 4 by firing a mixture of manganese oxide and a lithium material (patent) Reference 1), a method of obtaining a composite oxide of lithium and nickel by firing a mixture of a nickel compound such as lithium nickel carbonate or nickel nitrate and a lithium compound such as lithium nitrate or lithium carbonate in the air or in an oxygen atmosphere (Patent Document 2), a method of obtaining a powdered solid obtained by spray drying a solid-liquid mixture obtained by pulverizing a lithium compound and a transition metal compound in an aqueous medium (Patent Document 3), etc. It has been known.
特許文献１〜３に記載されている如く、従来の電極活物質は、金属化合物の混合物を固体状態で焼成して製造されているため、金属化合物相互を複合化させるために高温での焼成が必要であり、高温で焼成すると得られた金属複合化合物の粒子相互が溶着して巨大化し、粒径が５〜１０μｍ程度の粒子しか得ることができなかった。しかしながら、二次電池の出入力特性を向上させるために、電極活物質を更に微粒化することが求められている。また、二次電池は充放電を繰り返し行うと、徐々に活物質の劣化が生じて十分な充放電が行えなくなるが、従来の活物質を電極に用いた二次電池は、充放電のサイクル特性が必ずしも満足できるものではなかった。 As described in Patent Documents 1 to 3, since the conventional electrode active material is manufactured by firing a mixture of metal compounds in a solid state, firing at a high temperature is required to make the metal compounds complex. Necessary, and when fired at a high temperature, the obtained metal composite compound particles were welded together to enlarge, and only particles having a particle size of about 5 to 10 μm could be obtained. However, it is required to further atomize the electrode active material in order to improve the input / output characteristics of the secondary battery. In addition, when a secondary battery is repeatedly charged and discharged, the active material gradually deteriorates and cannot be fully charged or discharged. However, a secondary battery using a conventional active material as an electrode has a cycle characteristic of charge and discharge. Was not always satisfactory.
本発明者は、従来の電極活物質よりも粒径の小さい活物質を得るべく、金属化合物を固体状態で焼成する従来方法に代えて、金属化合物の溶液を加熱して活物質を得る方法の検討を行った。この方法では、金属化合物を固体状態で加熱、焼成する従来の方法に比べ、より低い温度で加熱して活物質を得ることができるが、得られた活物質は極めて微細な粒子となってしまい、取り扱い性が極度に低下するという問題があった。本発明者は更に鋭意研究した結果、特定の高分子物質の存在下で、金属化合物の溶液を加熱して得られるアルカリ遷移金属複合物粒子よりなる活物質は、従来よりも微細でありながら、取り扱い易い適度な粒径であり、しかも加熱温度の違いによって粒径が異なったものとなることを見いだし、さらに粒子中に炭素成分が存在していると、二次電池の電極に用いた場合の充放電のサイクル特性が従来の活物質を用いたものよりも向上することを見いだし、本発明を完成するに至った。 In order to obtain an active material having a particle diameter smaller than that of a conventional electrode active material, the present inventor has replaced a conventional method of firing a metal compound in a solid state, and a method of obtaining an active material by heating a metal compound solution. Study was carried out. In this method, an active material can be obtained by heating at a lower temperature than in the conventional method in which a metal compound is heated and fired in a solid state, but the obtained active material becomes extremely fine particles. There was a problem that the handleability was extremely lowered. As a result of further diligent research, the present inventor has found that the active material composed of alkali transition metal composite particles obtained by heating a solution of a metal compound in the presence of a specific polymer substance is finer than the conventional one, It was found that the particle size is easy to handle and the particle size varies depending on the heating temperature, and if carbon components are present in the particles, The inventors have found that the charge / discharge cycle characteristics are improved as compared with those using conventional active materials, and have completed the present invention.
即ち本発明は、
（１）アルカリ金属と、遷移金属とを含むアルカリ遷移金属複合化合物粒子の内部に、炭素成分が存在していることを特徴とする電極活物質、
（２）平均粒径が５ｎｍ〜５００ｎｍである上記（１）の電極活物質、
（３）炭素成分が、炭素、エーテル基含有化合物、エステル基含有化合物、カルボキシル基含有化合物、アセチレン系化合物、セルロース系化合物より選ばれた１種又は２種以上である上記（１）又は（２）の電極活物質、
を要旨とするものである。
That is, the present invention
(1) An electrode active material characterized in that a carbon component is present inside an alkali transition metal composite compound particle containing an alkali metal and a transition metal,
(2) The electrode active material according to (1), wherein the average particle diameter is 5 nm to 500 nm,
(3) The above (1) or (2), wherein the carbon component is one or more selected from carbon, an ether group-containing compound, an ester group-containing compound, a carboxyl group-containing compound, an acetylene compound, and a cellulose compound. ) Electrode active material,
Is a summary.
本発明の電極活物質は、アルカリ金属化合物と遷移金属化合物を、固体状態で加熱して得たアルカリ遷移金属複合化合物よりなる従来の電極活物質よりも、小さい粒径を有するため、二次電池の出入力特性を向上できるとともに、粒径の異なる活物質を電極に用いることにより、出入力特性を目的に応じて調整することができる。また本発明の電極活物質は、粒子内部に炭素成分が存在していることにより、本発明の活物質を二次電池の電極として用いた場合、充放電によって活物質が膨張、収縮を繰り返しても活物質が割れにくいため、従来に比して充放電のサイクル特性を向上できる等の効果を有する。 Since the electrode active material of the present invention has a smaller particle size than a conventional electrode active material made of an alkali transition metal composite compound obtained by heating an alkali metal compound and a transition metal compound in a solid state, the secondary battery The input / output characteristics can be improved according to the purpose by using active materials having different particle diameters for the electrodes. In addition, the electrode active material of the present invention has a carbon component inside the particles, so that when the active material of the present invention is used as an electrode of a secondary battery, the active material repeatedly expands and contracts due to charge and discharge. However, since the active material is difficult to break, it has the effect of improving the charge / discharge cycle characteristics as compared with the conventional case.
本発明の電極活物質は、アルカリ金属化合物と、遷移金属化合物と、高分子化合物とを含む活物質形成溶液を、遷移金属化合物の熱分解開始温度以上の温度で加熱することにより得られるアルカリ遷移金属複合化合物粒子の内部に、炭素成分が存在している活物質である。アルカリ金属化合物としては、リチウム、ナトリウム等のアルカリ金属の塩化物、硝酸塩、硫酸塩、過塩素酸塩、酢酸塩、リン酸塩、臭素酸塩等が用いられる。なかでも入手が容易な塩化物、硝酸塩、酢酸塩が好ましい。具体的なリチウム化合物としては、例えばクエン酸リチウム四水和物、過塩素酸リチウム三水和物、酢酸リチウム二水和物、硝酸リチウム、リン酸リチウム等が挙げられ、ナトリウム化合物としては、例えば硝酸ナトリウム、酢酸ナトリウム等が挙げられる。アルカリ金属化合物は、１種又は２種以上を併用することができる。 The electrode active material of the present invention is an alkali transition obtained by heating an active material forming solution containing an alkali metal compound, a transition metal compound, and a polymer compound at a temperature equal to or higher than the thermal decomposition start temperature of the transition metal compound. It is an active material in which a carbon component is present inside the metal composite compound particles. Examples of the alkali metal compound include chlorides, nitrates, sulfates, perchlorates, acetates, phosphates, bromates, and the like of alkali metals such as lithium and sodium. Of these, chlorides, nitrates, and acetates that are readily available are preferred. Specific lithium compounds include, for example, lithium citrate tetrahydrate, lithium perchlorate trihydrate, lithium acetate dihydrate, lithium nitrate, lithium phosphate and the like, and sodium compounds include, for example, Examples thereof include sodium nitrate and sodium acetate. One or more alkali metal compounds can be used in combination.
遷移金属化合物としては、コバルト、ニッケル、マンガン、鉄、チタン、バナジウム、クロム、ランタン等の遷移金属の塩化物、硝酸塩、硫酸塩、過塩素酸塩、酢酸塩、リン酸塩、臭素酸塩、錯塩等が用いられる。なかでも、入手が容易な塩化物、硝酸塩、酢酸塩が好ましい。また遷移金属化合物のなかでも、安価なコバルト化合物、ニッケル化合物、マンガン化合物、鉄化合物、チタンの化合物が好ましい。遷移金属化合物は１種又は２種以上を併用することができる。 Transition metal compounds include chlorides, nitrates, sulfates, perchlorates, acetates, phosphates, bromates of transition metals such as cobalt, nickel, manganese, iron, titanium, vanadium, chromium, lanthanum, Complex salts and the like are used. Of these, readily available chlorides, nitrates and acetates are preferred. Of the transition metal compounds, inexpensive cobalt compounds, nickel compounds, manganese compounds, iron compounds, and titanium compounds are preferred. One or two or more transition metal compounds can be used in combination.
具体的な遷移金属化合物としては、例えば塩化コバルト（ＩＩ）六水和物、蟻酸コバルト（ＩＩ）二水和物、コバルト（ＩＩＩ）アセチルアセトナート、コバルト（ＩＩ）アセチルアセトナート二水和物、酢酸コバルト（ＩＩ）四塩、しゅう酸コバルト（ＩＩ）二水和物、硝酸コバルト（ＩＩ）六水和物、塩化コバルト（ＩＩ）アンモニウム六水和物、亜硝酸コバルト（ＩＩＩ）ナトリウム、硫酸コバルト（ＩＩ）七水和物等のコバルト化合物、塩化ニッケル（ＩＩ）六水和物、酢酸ニッケル（ＩＩ）四水和物、過塩素酸ニッケル（ＩＩ）六水和物、臭化ニッケル（ＩＩ）三水和物、硝酸ニッケル（ＩＩ）六水和物、ニッケル（ＩＩ）アセチルアセトナート二水和物、次亜リン酸ニッケル（ＩＩ）六水和物、硫酸ニッケル（ＩＩ）六水和物等のニッケル化合物、酢酸マンガン（ＩＩＩ）二水和物、酢酸マンガン（ＩＩ）四水和物、硝酸マンガン（ＩＩ）六水和物、硫酸マンガン（ＩＩ）五水和物、シュウ酸マンガン（ＩＩ）二水和物、マンガン（ＩＩＩ）アセチルアセトナート等のマンガン化合物、塩化鉄（ＩＩ）四水和物、クエン酸鉄（ＩＩＩ）、酢酸鉄（ＩＩ）、しゅう酸鉄（ＩＩ）二水和物、硝酸鉄（ＩＩＩ）九水和物、乳酸鉄（ＩＩ）三水和物、リン酸鉄、硫酸鉄（ＩＩ）七水和物等の鉄化合物、四塩化チタン、チタンアセチルアセトナート等のチタン化合物が挙げられる。 Specific examples of the transition metal compound include cobalt (II) chloride hexahydrate, cobalt (II) formate dihydrate, cobalt (III) acetylacetonate, cobalt (II) acetylacetonate dihydrate, Cobalt acetate (II) tetrasalt, cobalt oxalate (II) dihydrate, cobalt nitrate (II) hexahydrate, cobalt chloride (II) ammonium hexahydrate, cobalt (III) sodium nitrite, cobalt sulfate (II) Cobalt compounds such as heptahydrate, nickel chloride (II) hexahydrate, nickel acetate (II) tetrahydrate, nickel (II) perchlorate hexahydrate, nickel (II) bromide Trihydrate, nickel (II) nitrate hexahydrate, nickel (II) acetylacetonate dihydrate, nickel (II) hypophosphite hexahydrate, nickel (II) sulfate hexahydrate, etc. Nickel compound, manganese (III) acetate dihydrate, manganese (II) acetate tetrahydrate, manganese nitrate (II) hexahydrate, manganese (II) sulfate pentahydrate, manganese (II) oxalate Hydrates, manganese compounds such as manganese (III) acetylacetonate, iron (II) chloride tetrahydrate, iron (III) citrate, iron (II) acetate, iron (II) oxalate dihydrate, Iron compounds such as iron (III) nitrate nonahydrate, iron (II) lactate trihydrate, iron phosphate, iron (II) sulfate heptahydrate, etc., titanium compounds such as titanium tetrachloride, titanium acetylacetonate Is mentioned.
高分子物質としては、遷移金属化合物の熱分解開始温度における加熱重量減少率が１００重量％未満の高分子物質が用いられる。高分子物質としては、メチルセルロース、エチルセルロース等のセルロース系高分子、ポリエチレングリコール、ポリプロピレングリコール、ポリエチレン−プロピレングリコール等のポリアルキレングリコール、ポリエチレンオキサイド、プロピレンオキサイド、アクリル系樹脂、ウレタン系樹脂、エポキシ系樹脂、フェノール系樹脂、メラミン系樹脂、ポリ酢酸ビニル、ポリエチレン、ポリプロピレン、ポリエーテル等のうち、使用する遷移金属化合物の熱分解開始温度における加熱重量減少率が１００重量％未満のものを選択して用いることが好ましく、これらのなかでも特にセルロース系高分子、ポリエチレングリコール等のポリアルキレングリコール、アクリル系樹脂、ウレタン系樹脂が好ましい。 As the polymer substance, a polymer substance having a heating weight reduction rate of less than 100% by weight at the thermal decomposition start temperature of the transition metal compound is used. Examples of the polymer substance include cellulose polymers such as methylcellulose and ethylcellulose, polyalkylene glycols such as polyethylene glycol, polypropylene glycol, and polyethylene-propylene glycol, polyethylene oxide, propylene oxide, acrylic resins, urethane resins, epoxy resins, Select and use phenolic resin, melamine resin, polyvinyl acetate, polyethylene, polypropylene, polyether, etc., whose transition weight reduction rate at the thermal decomposition start temperature of the transition metal compound used is less than 100% by weight. Among these, cellulose polymers, polyalkylene glycols such as polyethylene glycol, acrylic resins, and urethane resins are particularly preferable.
アルカリ金属化合物の熱分解開始温度は、遷移金属化合物の熱分解開始温度よりも高い温度であるが、遷移金属化合物が存在していることにより、アルカリ金属化合物の熱分解開始温度よりも低い温度であっても、遷移金属化合物の熱分解開始温度以上の温度で加熱しても活物質を得ることができる。また、活物質形成溶液中に、遷移金属化合物の熱分解開始温度における加熱重量減少率が１００重量％未満の高分子物質が共存していることにより、活物質形成溶液を遷移金属化合物の熱分解開始温度以上に加熱した際に、高分子物質に活物質結晶の成長が阻害されるために微細な結晶が生成し、この微細結晶が更に加熱した際に成長することで、より大きな粒径の活物質が得られると考えられる。本発明において上記遷移金属化合物の熱分解開始温度とは、遷移金属化合物を１２０℃で１０分保持した後、１０℃／分の速度で昇温加熱した時に、５重量％の重量減少が生じた時の温度とする。熱分解開始温度は、遷移金属化合物を熱天秤により昇温加熱して測定することができる。また高分子物質の加熱重量変化率は、高分子物質を１０℃／分の速度で昇温加熱して遷移金属化合物の熱分解開始温度に達した時の重量の、元の重量に対する重量変化率として求めることができる。高分子物質の加熱重量変化は、熱天秤により高分子物質を昇温加熱した際の重量変化を測定することで求めることができる。尚、複数の遷移金属化合物を併用する場合、各遷移金属化合物の熱分解開始温度のうち、最も低い温度を遷移金属化合物の熱分解開始温度として採用する。 The thermal decomposition start temperature of the alkali metal compound is higher than the thermal decomposition start temperature of the transition metal compound. However, due to the presence of the transition metal compound, the thermal decomposition start temperature is lower than the thermal decomposition start temperature of the alkali metal compound. Even in such a case, the active material can be obtained by heating at a temperature equal to or higher than the thermal decomposition start temperature of the transition metal compound. In addition, the active material forming solution is thermally decomposed of the transition metal compound by the coexistence of a polymer material having a heating weight reduction rate of less than 100% by weight at the thermal decomposition starting temperature of the transition metal compound. When heated above the starting temperature, the growth of active material crystals is hindered by the polymer material, resulting in the formation of fine crystals, and the fine crystals grow when heated further, resulting in a larger particle size. It is thought that an active material is obtained. In the present invention, the thermal decomposition start temperature of the transition metal compound means that the transition metal compound was held at 120 ° C. for 10 minutes and then heated at a rate of 10 ° C./min. The temperature of the hour. The thermal decomposition starting temperature can be measured by heating the transition metal compound with a thermobalance. Further, the weight change rate of the polymer material by weight is the weight change rate of the weight when the polymer material is heated at a rate of 10 ° C./min to reach the thermal decomposition start temperature of the transition metal compound relative to the original weight. Can be obtained as The change in weight of the polymer material by heating can be determined by measuring the change in weight when the polymer material is heated by heating using a thermobalance. In addition, when using a some transition metal compound together, the lowest temperature is employ | adopted as the thermal decomposition start temperature of a transition metal compound among the thermal decomposition start temperatures of each transition metal compound.
アルカリ金属化合物、遷移金属化合物、高分子物質を含む活物質形成溶液における溶媒としては、水や、メチルアルコール、エチルアルコール、プロピルアルコール、イソプロピルアルコール、ブチルアルコール等の総炭素数５以下の低級アルコール、アセチルアセトン、ジアセチル、ベンゾイルアセトン等のジケトン類、アセト酢酸エチル、ピルビン酸エチル、ベンゾイル酢酸エチル、ベンゾイル蟻酸エチル等のケトエステル類、トルエン等が挙げられ、これらの中からアルカリ金属化合物、遷移金属化合物、高分子物質を溶解させるに適した溶媒を選択して用いる。また、アルカリ金属化合物、遷移金属化合物、高分子物質の溶解性を高める等の目的で、２種以上の溶媒を組みあわせた混合溶媒を用いることもできる。混合溶媒としては、例えば水−メチルアルコール混合溶媒、水−エチルアルコール混合溶媒、水−イソプロピルアルコール混合溶媒、等の水とアルコールとの混合溶媒等が挙げられる。 As a solvent in an active material forming solution containing an alkali metal compound, a transition metal compound, and a polymer material, water, a lower alcohol having a total carbon number of 5 or less such as methyl alcohol, ethyl alcohol, propyl alcohol, isopropyl alcohol, and butyl alcohol, Examples include diketones such as acetylacetone, diacetyl and benzoylacetone, ketoesters such as ethyl acetoacetate, ethyl pyruvate, ethyl benzoylacetate and ethyl benzoylformate, and toluene. Among these, alkali metal compounds, transition metal compounds, high A solvent suitable for dissolving the molecular substance is selected and used. In addition, for the purpose of increasing the solubility of alkali metal compounds, transition metal compounds, and polymer substances, a mixed solvent in which two or more solvents are combined can be used. Examples of the mixed solvent include a mixed solvent of water and alcohol such as a water-methyl alcohol mixed solvent, a water-ethyl alcohol mixed solvent, and a water-isopropyl alcohol mixed solvent.
上記活物質形成溶液を遷移金属化合物の熱分解開始温度以上に加熱する方法としては、活物質形成溶液を、るつぼ等の容器に入れて加熱炉内で加熱する方法、加熱炉内に活物質形成溶液を噴霧して加熱する方法等が挙げられるが、活物質形成溶液を噴霧して加熱する方法では、るつぼ等の容器内で活物質形成溶液を加熱する方法に比べ、より粒径が小さい活物質を得ることができる。加熱温度は遷移金属化合物の熱分解開始温度以上の温度であれば良いが、遷移金属化合物の熱分解開始温度以上の温度に加熱して生成した活物質粒子相互が融着するのを防止する上で、加熱温度は、遷移金属化合物の熱分解開始温度以上、６００℃以下の温度が好ましい。活物質形成溶液を遷移金属化合物の熱分解開始温度以上の温度で加熱して活物質粒子を生成させた後、より高い温度に昇温して更に加熱を行うこともでき、このような加熱を行うことにより、活物質形成溶液を遷移金属化合物の熱分解開始温度以上の温度で加熱して形成した活物質粒子をより大きな径の粒子とすることができ、昇温して加熱する温度を高くするほど、最終的に得られる活物質の粒径を大きくすることができる。活物質形成溶液を遷移金属化合物の熱分解開始温度以上の温度で加熱して生成した活物質を、更に高い温度で加熱する場合、加熱温度が高すぎると生成した活物質粒子の溶着が生じてしまうため、昇温加熱する場合の温度は得られた活物質が溶着しない程度の温度以下であり、６００℃以下の温度が好ましい。 As a method of heating the active material forming solution above the thermal decomposition start temperature of the transition metal compound, the active material forming solution is placed in a container such as a crucible and heated in a heating furnace, or the active material is formed in the heating furnace. Examples include a method of spraying and heating the solution, but the method of spraying and heating the active material forming solution has a smaller particle size than the method of heating the active material forming solution in a container such as a crucible. A substance can be obtained. The heating temperature may be a temperature equal to or higher than the thermal decomposition start temperature of the transition metal compound, but it is possible to prevent the active material particles generated by heating to a temperature equal to or higher than the thermal decomposition start temperature of the transition metal compound from fusing together. The heating temperature is preferably a temperature not lower than the thermal decomposition start temperature of the transition metal compound and not higher than 600 ° C. After the active material forming solution is heated at a temperature equal to or higher than the thermal decomposition start temperature of the transition metal compound to generate active material particles, the temperature can be raised to a higher temperature and further heating can be performed. By doing so, the active material particles formed by heating the active material forming solution at a temperature equal to or higher than the thermal decomposition start temperature of the transition metal compound can be made into particles having a larger diameter, and the temperature at which the temperature is increased by heating is increased. The particle size of the active material finally obtained can be increased as the value is increased. When the active material formed by heating the active material forming solution at a temperature equal to or higher than the thermal decomposition start temperature of the transition metal compound is heated at a higher temperature, if the heating temperature is too high, welding of the generated active material particles occurs. For this reason, the temperature for heating and heating is not higher than the temperature at which the obtained active material is not welded, and is preferably 600 ° C. or lower.
上記活物質形成溶液中には、必要によりアセチレンブラック、カーボンファイバー等の導電剤を配合しても良く、導電剤を配合した活物質形成溶液を用いると、活物質と導電剤との複合体を得ることができる。 In the active material forming solution, a conductive agent such as acetylene black and carbon fiber may be blended if necessary. When an active material forming solution in which a conductive agent is blended is used, a composite of the active material and the conductive agent is formed. Can be obtained.
アルカリ遷移金属複合化合物粒子の内部に炭素成分が存在する本発明の活物質は、上記高分子物質として、活物質形成溶液を遷移金属化合物の熱分解開始温度以上の温度に加熱して活物質を得る加熱工程において、加熱終了後にも高分子物質の加熱重量減少率が１００重量％とならないような加熱条件を選択するか、設定した加熱条件において加熱終了後に加熱重量減少率が１００重量％とならない高分子物質を選択するか、あるいは設定した加熱条件での加熱工程終了後に加熱重量減少率が１００重量％とならないように過剰の高分子物質を添加しておき、活物質中に高分子物質あるいは高分子物質の分解物が炭素成分として残存するようにする等により得ることができる。この場合、活物質中の炭素成分としては、活物質形成溶液に添加した高分子物質や、該高分子物質の熱分解によって生じた炭素、エーテル基含有化合物、エステル基含有化合物、カルボキシル基含有化合物、アセチレン系化合物、セルロース系化合物、あるいはこれらの混合物が挙げられる。炭素成分の種類は、活物質の赤外線吸収スペクトルを測定して確認することができる。 The active material of the present invention in which the carbon component is present inside the alkali transition metal composite compound particles is obtained by heating the active material forming solution to a temperature equal to or higher than the thermal decomposition start temperature of the transition metal compound as the polymer material. In the heating process to be obtained, a heating condition is selected such that the heating weight reduction rate of the polymer substance does not become 100% by weight even after the heating is finished, or the heating weight reduction rate does not become 100% by weight after the heating is finished in the set heating conditions. Select a polymer substance, or add an excess polymer substance so that the heating weight reduction rate does not become 100% by weight after the heating process under the set heating conditions, and add a polymer substance or It can be obtained, for example, by leaving a decomposition product of the polymer substance as a carbon component. In this case, the carbon component in the active material includes a polymer material added to the active material forming solution, carbon generated by thermal decomposition of the polymer material, an ether group-containing compound, an ester group-containing compound, and a carboxyl group-containing compound. , An acetylene compound, a cellulose compound, or a mixture thereof. The kind of carbon component can be confirmed by measuring the infrared absorption spectrum of the active material.
本発明の電極活物質中に炭素成分が存在していることは、例えば電極活物質を、透過型電子顕微鏡（ＴＥＭ）を用い、走査透過型電子顕微鏡法（ＳＴＥＭ法）によって観察し、ＥＤＸ検出器でナノオーダーの元素分析により示される元素マッピングによって確認することができる。 The presence of the carbon component in the electrode active material of the present invention means that, for example, the electrode active material is observed by scanning transmission electron microscopy (STEM method) using a transmission electron microscope (TEM), and EDX detection is performed. It can be confirmed by element mapping shown by nano-order elemental analysis on a vessel.
本発明の電極活物質であるアルカリ遷移金属複合化合物としては、アルカリ遷移金属複合酸化物、アルカリ遷移金属複合窒化物、アルカリ遷移金属複合硫化物、アルカリ遷移金属複合リン酸化合物等が挙げられる。アルカリ遷移金属複合酸化物は、上記活物質形成溶液を酸素ガス雰囲気下で加熱することにより得ることができ、アルカリ遷移金属複合窒化物は、上記活物質形成溶液をアンモニアガス雰囲気下で加熱することにより得ることができ、アルカリ遷移金属複合硫化物は、上記アルカリ金属化合物、遷移金属化合物、高分子物質と共に、チオ硫酸ナトリウム、チオ硫酸カリウム、チオ硫酸アンモニウム、チオ硫酸カルシウムなどを含む活物質形成溶液を加熱することにより得ることができる。またアルカリ遷移金属複合リン酸化合物を得る場合には、リンを含む活物質形成溶液を加熱することにより得ることができる。 Examples of the alkali transition metal composite compound that is the electrode active material of the present invention include alkali transition metal composite oxides, alkali transition metal composite nitrides, alkali transition metal composite sulfides, and alkali transition metal composite phosphate compounds. The alkali transition metal composite oxide can be obtained by heating the active material forming solution in an oxygen gas atmosphere. The alkali transition metal composite oxide can be obtained by heating the active material forming solution in an ammonia gas atmosphere. The alkali transition metal composite sulfide is an active material forming solution containing sodium thiosulfate, potassium thiosulfate, ammonium thiosulfate, calcium thiosulfate and the like together with the alkali metal compound, transition metal compound, and polymer material. It can be obtained by heating. Moreover, when obtaining an alkali transition metal composite phosphoric acid compound, it can obtain by heating the active material formation solution containing phosphorus.
アルカリ遷移金属複合リン酸化合物を得るには、活物質製造原料であるアルカリ金属化合物、遷移金属化合物中にリンが含まれない場合、活物質形成溶液に、更にリン含有化合物を添加することが必要である。リン含有化合物としては、メタリン酸、ピロリン酸、オルトリン酸、三リン酸、四リン酸や、これらの塩等のリン酸類、亜リン酸や亜リン酸塩等の亜リン酸類、次亜リン酸や次亜リン酸塩等の次亜リン酸類が挙げられる。 In order to obtain an alkali transition metal composite phosphate compound, it is necessary to add a phosphorus-containing compound to the active material forming solution when phosphorus is not contained in the alkali metal compound or transition metal compound that is the active material production raw material. It is. Phosphorus-containing compounds include metaphosphoric acid, pyrophosphoric acid, orthophosphoric acid, triphosphoric acid, tetraphosphoric acid, phosphoric acids such as salts thereof, phosphorous acids such as phosphorous acid and phosphite, hypophosphorous acid And hypophosphorous acids such as hypophosphites.
上記活物質の具体的な例としては、例えば、ＬｉＭｎＯ２、ＬｉＭｎ２Ｏ４、ＬｉＮｉＯ２、Ｌｉ４Ｔｉ５Ｏ１２、ＬｉＦｅＯ２、ＬｉＦｅＰＯ４、ＬｉＣｏＯ２、ＬｉＮｉ０．３３ＣｏＬｉＮｉ０．３３ＭｎＬｉＮｉ０．３３Ｏ２等が挙げられる。 Specific examples of the active material include, for example, LiMnO 2 , LiMn 2 O 4 , LiNiO 2 , Li 4 Ti 5 O 12 , LiFeO 2 , LiFePO 4 , LiCoO 2 , LiNi 0.33 CoLiNi 0.33 MnLiNi 0. .33 O 2 and the like.
本発明の活物質は、平均粒径が５ｎｍ〜５００ｎｍが好ましいが、２０ｎｍ〜２００ｎｍがより好ましい。活物質形成溶液をるつぼ等の容器に入れて加熱する方法では、平均粒径２０ｎｍ〜５００ｎｍ程度の活物質を得ることができ、活物質形成溶液を加熱雰囲気下に噴霧して加熱する方法では平均粒径５ｎｍ〜２００ｎｍ程度の活物質を得ることができる。上記活物質の平均粒径は、活物質を走査型電子顕微鏡（ＳＥＭ）で観察し（倍率５万倍程度）、画像解析式粒度分布測定ソフトウェア（株式会社マウンテック製、ＭＡＣ ＶＩＥＷ）を用いて、粒子２０個を測定して得られたデータを平均して求めた値である。 The average particle diameter of the active material of the present invention is preferably 5 nm to 500 nm, but more preferably 20 nm to 200 nm. In the method of heating the active material forming solution in a container such as a crucible, an active material having an average particle size of about 20 nm to 500 nm can be obtained. In the method of heating by spraying the active material forming solution in a heating atmosphere, the average is obtained. An active material having a particle size of about 5 nm to 200 nm can be obtained. The average particle diameter of the active material is observed with a scanning electron microscope (SEM) (magnification of about 50,000 times), and using image analysis type particle size distribution measurement software (manufactured by Mount Tech Co., Ltd., MAC VIEW), This is a value obtained by averaging data obtained by measuring 20 particles.
以下、実施例、比較例を挙げて本発明を更に詳細に説明する。 Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples.
実施例１
酢酸リチウム二水和物１０．２ｇ、硝酸ニッケル（ＩＩ）六水和物（熱分解開始温度１９０℃）９．７ｇ、硝酸マンガン（ＩＩ）六水和物（熱分解開始温度２００℃）９．６ｇ、硝酸コバルト六水和物（熱分解開始温度２１０℃）９．７ｇ、メチルセルロース（信越化学株式会社製、メトローズ６５ＳＨ−１５００：硝酸ニッケルの熱分解開始温度１９０℃における加熱重量減少率４重量％）３ｇを、水：イソプロピルアルコール（２：１）の混合溶媒７０ｇに添加し、バイオシェーカーにより回転数２００ｒｐｍで７０℃にて５時間攪拌し、その後、２４時間室温で保持したものを活物質形成溶液とした。この溶液をるつぼに入れ、大気雰囲気の焼成炉（光洋サーモシステム社製）中で、室温から１時間かけて２００℃に昇温し、２００℃で１時間保持した。次いで、５００℃まで２０分かけて昇温した後、直ちに焼成炉を開放して粉体を取り出した。また上記と同様の活物質形成溶液を同様にして焼成炉内で室温から１時間かけて２００℃に昇温し、２００℃で１時間保持した後、６００℃まで１時間かけて昇温した後、直ちに焼成炉を開放して粉体を取り出した。これらの粉体のＸ線回折測定したところ、いずれもＬｉＮｉ０．３３Ｃｏ０．３３Ｍｎ０．３３Ｏ２で示される活物質であることが確認された。得られた活物質を走査型電子顕微鏡（ＳＥＭ）で観察し、画像解析式粒度分布測定ソフトウェア（株式会社マウンテック製：ＭＡＣ ＶＩＥＷ）により粒子２０点の平均粒径を求めたところ、２００℃で１時間保持した後、５００℃まで２０分かけて昇温して取り出して得た活物質の平均粒径は４７ｎｍであり、２００℃で１時間保持した後、６００℃まで１時間かけて昇温して取り出して得た活物質の平均粒径は１３３ｎｍであった。得られた活物質を、透過型電子顕微鏡（ＴＥＭ）を用いて観察した結果、電極活物質中に炭素成分の存在が確認された。
Example 1
10.2 g of lithium acetate dihydrate, 9.7 g of nickel nitrate (II) hexahydrate (thermal decomposition start temperature 190 ° C.), manganese nitrate (II) hexahydrate (thermal decomposition start temperature 200 ° C.) 6 g, cobalt nitrate hexahydrate (pyrolysis start temperature 210 ° C.) 9.7 g, methylcellulose (manufactured by Shin-Etsu Chemical Co., Ltd., Metroz 65SH-1500: heating weight decrease rate of nickel nitrate at 190 ° C. heat loss 4% by weight ) 3 g was added to 70 g of a mixed solvent of water: isopropyl alcohol (2: 1), stirred at 70 ° C. for 5 hours with a bioshaker at 70 ° C., and then held at room temperature for 24 hours to form an active material It was set as the solution. This solution was put in a crucible and heated from room temperature to 200 ° C. over 1 hour in an atmospheric baking furnace (manufactured by Koyo Thermo System Co., Ltd.) and held at 200 ° C. for 1 hour. Subsequently, after heating up to 500 degreeC over 20 minutes, the baking furnace was open | released immediately and powder was taken out. In addition, the same active material forming solution as above was heated from room temperature to 200 ° C. over 1 hour in a baking furnace, held at 200 ° C. for 1 hour, and then heated to 600 ° C. over 1 hour. The firing furnace was immediately opened and the powder was taken out. X-ray diffraction measurement of these powders confirmed that all were active materials represented by LiNi 0.33 Co 0.33 Mn 0.33 O 2 . The obtained active material was observed with a scanning electron microscope (SEM), and the average particle size of 20 particles was determined by an image analysis type particle size distribution measurement software (manufactured by Mount Tech Co., Ltd .: MAC VIEW). The average particle size of the active material obtained by heating up to 500 ° C. over 20 minutes after taking out the time was 47 nm. After holding at 200 ° C. for 1 hour, the temperature was raised to 600 ° C. over 1 hour. The average particle size of the active material obtained by taking out was 133 nm. As a result of observing the obtained active material using a transmission electron microscope (TEM), the presence of a carbon component was confirmed in the electrode active material.
比較例１
メチルセルロースを含まない活物質形成溶液を用いた他は、実施例１と同様にして同様の組成の活物質を得た。２００℃で１時間保持した後、５００℃まで２０分かけて昇温して得た活物質の平均粒径は２４ｎｍであり、２００℃で１時間保持した後、６００℃まで１時間かけて昇温して得た活物質の平均粒径は２７ｎｍであった。得られた活物質を、透過型電子顕微鏡（ＴＥＭ）を用いて観察した結果、電極活物質中に炭素成分の存在は確認されなかった。
Comparative Example 1
An active material having the same composition was obtained in the same manner as in Example 1 except that an active material forming solution not containing methylcellulose was used. After maintaining at 200 ° C. for 1 hour, the average particle size of the active material obtained by raising the temperature to 500 ° C. over 20 minutes is 24 nm. After holding at 200 ° C. for 1 hour, it rises to 600 ° C. over 1 hour. The average particle size of the active material obtained by heating was 27 nm. As a result of observing the obtained active material using a transmission electron microscope (TEM), the presence of a carbon component in the electrode active material was not confirmed.
実施例２
実施例１と同様の活物質形成溶液を、３００℃に加熱した大気雰囲気の炉内にスプレー装置（ノードソン社製）により噴霧して粉体を得た。得られた粉体を冷却した後、大気雰囲気の焼成炉に入れ、５００℃まで２０分かけて昇温した後、直ちに焼成炉を開放し、平均粒径１７ｎｍの粉体を得た。また上記と同様に、加熱炉内で活物質形成溶液を噴霧して得た粉体を、焼成炉内で６００℃まで1時間かけて昇温した後、直ちに焼成炉を開放し、平均粒径８２ｎｍの粉体を得た。これらの粉体はＸ線回折により、実施例１と同様の組成の活物質であることが確認された。得られた活物質を、透過型電子顕微鏡（ＴＥＭ）を用いて観察した結果、電極活物質中に炭素成分の存在が確認された。
Example 2
An active material forming solution similar to that in Example 1 was sprayed by a spray device (manufactured by Nordson) into an atmospheric furnace heated to 300 ° C. to obtain a powder. After cooling the obtained powder, it was put into a firing furnace in an air atmosphere and heated up to 500 ° C. over 20 minutes, and then the firing furnace was immediately opened to obtain a powder having an average particle diameter of 17 nm. Similarly to the above, after the powder obtained by spraying the active material forming solution in the heating furnace was heated to 600 ° C. over 1 hour in the baking furnace, the baking furnace was immediately opened and the average particle size was increased. An 82 nm powder was obtained. These powders were confirmed to be active materials having the same composition as in Example 1 by X-ray diffraction. As a result of observing the obtained active material using a transmission electron microscope (TEM), the presence of a carbon component was confirmed in the electrode active material.
比較例２
メチルセルロースを含まない活物質形成溶液を用いた他は、実施例２と同様に加熱して同様の組成の活物質を得た。３００℃の炉内で噴霧して得た粉体を５００℃まで２０分かけて昇温加熱して得た活物質の平均粒径は７ｎｍであり、３００℃の炉内で噴霧して得た粉体を、６００℃まで1時間かけて昇温加熱して得た活物質の平均粒径は８ｎｍであった。得られた活物質を、透過型電子顕微鏡（ＴＥＭ）を用いて観察した結果、電極活物質中に炭素成分の存在は確認されなかった。
Comparative Example 2
Except using the active material formation solution which does not contain methylcellulose, it heated similarly to Example 2 and obtained the active material of the same composition. The average particle size of the active material obtained by heating the powder obtained by spraying in a 300 ° C. furnace to 500 ° C. over 20 minutes is 7 nm, and obtained by spraying in a 300 ° C. furnace. The average particle size of the active material obtained by heating the powder to 600 ° C. over 1 hour was 8 nm. As a result of observing the obtained active material using a transmission electron microscope (TEM), the presence of a carbon component in the electrode active material was not confirmed.
実施例３
酢酸リチウム二水和物５．１ｇ、酢酸マンガン（ＩＩ）四水和物（熱分解開始温度２００℃）２４．５ｇを、メチルアルコール２００ｇに添加し、バイオシェーカーにより回転数２００ｒｐｍで７０℃にて５時間攪拌して溶解させた後、アクリル樹脂（共栄社化学製、オリコックスＫＣ：酢酸マンガンの熱分解開始温度における加熱重量減少率３重量％）１０ｇを添加して活物質形成溶液を調製した。この溶液を、大気雰囲気下にて４００℃に加熱した炉内にスプレー装置（ノードソン社製）により噴霧して粉体を得た。得られた粉体を６０℃まで冷却し、平均粒径４５ｎｍの粉体を得た。また同様の活物質形成溶液を５００℃に加熱した炉内にスプレー装置（ノードソン社製）により噴霧して粉体を得た。得られた粉体を６０℃まで冷却し、平均粒径６１ｎｍの粉体を得た。これらの粉体はＸ線回折測定により、ＬｉＭｎ２Ｏ４で示される活物質であることが確認された。得られた活物質を、透過型電子顕微鏡（ＴＥＭ）を用いて観察した結果、電極活物質中に炭素成分の存在が確認され、ＩＲ測定により、アクリル基に特有の吸収スペクトルが確認された。
Example 3
Lithium acetate dihydrate 5.1 g and manganese (II) acetate tetrahydrate (thermal decomposition start temperature 200 ° C.) 24.5 g were added to 200 g of methyl alcohol, and a bioshaker at 70 ° C. at a rotation speed of 200 rpm. After stirring for 5 hours to dissolve, 10 g of an acrylic resin (manufactured by Kyoeisha Chemical Co., Ltd., Oricox KC: 3% by weight reduction in heating weight at the thermal decomposition start temperature of manganese acetate) was added to prepare an active material forming solution. This solution was sprayed with a spray device (manufactured by Nordson) into a furnace heated to 400 ° C. in an air atmosphere to obtain a powder. The obtained powder was cooled to 60 ° C. to obtain a powder having an average particle diameter of 45 nm. A similar active material forming solution was sprayed in a furnace heated to 500 ° C. with a spray device (manufactured by Nordson) to obtain a powder. The obtained powder was cooled to 60 ° C. to obtain a powder having an average particle diameter of 61 nm. These powders were confirmed to be an active material represented by LiMn 2 O 4 by X-ray diffraction measurement. As a result of observing the obtained active material using a transmission electron microscope (TEM), the presence of a carbon component was confirmed in the electrode active material, and an absorption spectrum peculiar to the acrylic group was confirmed by IR measurement.
比較例３
アクリル樹脂を含まない活物質形成溶液を用いた他は、実施例３と同様にして同様の組成の活物質を得た。４００℃の炉内で噴霧して得た活物質の平均粒径は９ｎｍであり、５００℃の炉内で噴霧して得た活物質の平均粒径は１１ｎｍであった。得られた活物質を、透過型電子顕微鏡（ＴＥＭ）を用いて観察した結果、電極活物質中に炭素成分の存在は確認されなかった。
Comparative Example 3
An active material having the same composition was obtained in the same manner as in Example 3 except that an active material forming solution not containing an acrylic resin was used. The average particle diameter of the active material obtained by spraying in a furnace at 400 ° C. was 9 nm, and the average particle diameter of the active material obtained by spraying in a furnace at 500 ° C. was 11 nm. As a result of observing the obtained active material using a transmission electron microscope (TEM), the presence of a carbon component in the electrode active material was not confirmed.
実施例４
酢酸リチウム二水和物１０．２ｇ、硝酸鉄（ＩＩＩ）九水和物（熱分解開始温度１８０℃）４０．４ｇ、リン酸９．８ｇ、メチルセルロース（信越化学株式会社製、メトローズ６５ＳＨ−１５００：硝酸鉄の熱分解開始温度における加熱重量減少率６重量％）２ｇを、水１００ｇ、メチルアルコール４５ｇの混合溶媒に添加し、バイオシェーカーにより回転数２００ｒｐｍで７０℃にて１時間攪拌して活物質形成溶液を調製した。この溶液をるつぼに入れ、４％の水素を含んだ窒素ガスでパージした焼成炉中で、室温から１時間かけて２００℃に昇温し、同温度で１時間保持した。次いで、３８０℃まで２０分かけて昇温した後、窒素ガスをパージしながら６０℃まで冷却し、平均粒径３５ｎｍの粉体を得た。同様の活物質形成溶液を同様にして焼成炉内で室温から１時間かけて２００℃に昇温し、同温度で１時間保持した後、５００℃まで２０分かけて昇温した後、窒素ガスをパージしながら６０℃まで冷却し、平均粒径５７ｎｍの粉体を得た。これらの粉体はＸ線回折測定により、ＬｉＦｅＰＯ４で示される活物質であることが確認された。得られた活物質を、透過型電子顕微鏡（ＴＥＭ）を用いて観察した結果、３８０℃まで２０分かけて昇温したものも、５００℃まで２０分かけて昇温したものも、電極活物質中に炭素成分の存在が確認されたが、ＩＲ測定により、３８０℃まで昇温したものはセルロース基に特有の吸収スペクトルを確認するも、５００℃まで昇温したものはＩＲによるセルロースに特有な吸収スペクトルは認められなかった。これは、５００℃まで昇温したものでは、セルロース構造が壊れた炭素成分の状態で存在していると推測される。
Example 4
Lithium acetate dihydrate 10.2 g, iron (III) nitrate nonahydrate (thermal decomposition start temperature 180 ° C.) 40.4 g, phosphoric acid 9.8 g, methylcellulose (manufactured by Shin-Etsu Chemical Co., Ltd., Metrose 65SH-1500): 2 g of heating weight reduction rate at the thermal decomposition start temperature of iron nitrate was added to a mixed solvent of 100 g of water and 45 g of methyl alcohol, and the active material was stirred at 70 ° C. for 1 hour at a rotation speed of 200 rpm with a bioshaker. A forming solution was prepared. This solution was put in a crucible, heated from room temperature to 200 ° C. over 1 hour in a firing furnace purged with nitrogen gas containing 4% hydrogen, and kept at that temperature for 1 hour. Subsequently, after heating up to 380 degreeC over 20 minutes, it cooled to 60 degreeC, purging nitrogen gas, and obtained the powder with an average particle diameter of 35 nm. Similarly, after raising the temperature of the same active material forming solution from room temperature to 200 ° C. over 1 hour in the firing furnace, holding the same temperature for 1 hour, raising the temperature to 500 ° C. over 20 minutes, and then adding nitrogen gas Was cooled to 60 ° C. while purging, to obtain a powder having an average particle size of 57 nm. These powders were confirmed to be an active material represented by LiFePO 4 by X-ray diffraction measurement. As a result of observing the obtained active material using a transmission electron microscope (TEM), those heated up to 380 ° C. over 20 minutes, those heated up to 500 ° C. over 20 minutes, electrode active materials The presence of a carbon component was confirmed, but by IR measurement, an absorption spectrum peculiar to the cellulose group was confirmed when the temperature was raised to 380 ° C., but that heated to 500 ° C. was characteristic of cellulose by IR Absorption spectrum was not observed. This is presumed that when the temperature is raised to 500 ° C., the cellulose structure is present in a broken carbon component state.
比較例４
メチルセルロースを含まない活物質形成溶液を用いた他は、実施例４と同様にして同様の組成の活物質を得た。２００℃で１時間保持した後、３８０℃まで２０分かけて昇温加熱して得た活物質の平均粒径は１６ｎｍであり、２００℃で１時間保持した後、５００℃まで２０分℃まで昇温加熱して得た活物質の平均粒径は１５ｎｍであった。得られた活物質を、透過型電子顕微鏡（ＴＥＭ）を用いて観察した結果、電極活物質中に炭素成分の存在は確認されなかった。
Comparative Example 4
An active material having the same composition was obtained in the same manner as in Example 4 except that an active material forming solution containing no methylcellulose was used. After holding at 200 ° C. for 1 hour, the average particle size of the active material obtained by heating up to 380 ° C. over 20 minutes is 16 nm. After holding at 200 ° C. for 1 hour, it reaches 500 ° C. up to 20 minutes. The average particle size of the active material obtained by heating at elevated temperature was 15 nm. As a result of observing the obtained active material using a transmission electron microscope (TEM), the presence of a carbon component in the electrode active material was not confirmed.
実施例５
硝酸リチウム６．９ｇ、塩化ニッケル（ＩＩ）六水和物（熱分解開始温度２００℃）２３．８ｇ、ポリエチレングリコール２００００（関東化学社製：塩化ニッケルの熱分解開始温度における加熱重量減少率２重量％）５ｇを、水：エチルアルコール（２：１）の混合溶媒１５０ｇに添加し、バイオシェーカーにより回転数２００ｒｐｍで７０℃にて５時間攪拌し、その後、２時間室温で保持したものを活物質形成溶液とした。この活物質形成溶液を、酸素９９．５％ガスでパージし、２００℃に加熱した炉内にスプレー装置（ノードソン社製）により噴霧して粉体を得た。得られた粉体を冷却した後、酸素９９．５％ガスでパージした焼成炉に入れ、４００℃まで２０分かけて昇温した後、焼成炉から取り出して、平均粒径２２ｎｍの粉体を得た。同様の活物質形成溶液を同様にして、２００℃に加熱した炉内にスプレー装置（ノードソン社製）により噴霧して得た粉体を冷却した後、酸素９９．５％ガスでパージした焼成炉に入れ、６００℃まで６０分かけて昇温した後、焼成炉から取り出して、平均粒径２４８ｎｍの粉体を得た。これらの粉体はＸ線回折により、ＬｉＮｉＯ２で示される活物質であることが確認された。得られた活物質を、透過型電子顕微鏡（ＴＥＭ）を用いて観察した結果、電極活物質中に炭素成分の存在が確認された。
Example 5
Lithium nitrate 6.9 g, nickel chloride (II) hexahydrate (thermal decomposition start temperature 200 ° C.) 23.8 g, polyethylene glycol 20000 (manufactured by Kanto Chemical Co., Inc .: 2% weight loss by heating at the thermal decomposition start temperature of nickel chloride) %) Was added to 150 g of a mixed solvent of water: ethyl alcohol (2: 1), stirred for 5 hours at 70 ° C. at 200 rpm with a bioshaker, and then kept at room temperature for 2 hours as an active material. Formed solution. This active material forming solution was purged with 99.5% oxygen gas and sprayed into a furnace heated to 200 ° C. with a spray device (manufactured by Nordson) to obtain a powder. After cooling the obtained powder, it was placed in a firing furnace purged with 99.5% oxygen gas, heated to 400 ° C. over 20 minutes, and then taken out from the firing furnace to obtain a powder having an average particle diameter of 22 nm. Obtained. Similarly, the same active material forming solution was cooled in a furnace heated to 200 ° C. using a spray device (manufactured by Nordson), and then the powder obtained by cooling was purged with 99.5% oxygen gas. And heated to 600 ° C. over 60 minutes, and then taken out from the firing furnace to obtain a powder having an average particle size of 248 nm. These powders were confirmed to be an active material represented by LiNiO 2 by X-ray diffraction. As a result of observing the obtained active material using a transmission electron microscope (TEM), the presence of a carbon component was confirmed in the electrode active material.
比較例５
ポリエチレングリコールを含まない活物質形成溶液を用いた他は、実施例５と同様にして同様の組成の活物質を得た。４００℃の炉内で噴霧して得た粉体を焼成炉内で４００℃まで２０分かけて昇温加熱して得た活物質の平均粒径は１８ｎｍであり、４００℃の炉内で噴霧して得た粉体を、加熱炉内で６００℃まで６０分かけて昇温加熱して得た活物質の平均粒径は１５ｎｍであった。得られた活物質を、透過型電子顕微鏡（ＴＥＭ）を用いて観察した結果、電極活物質中に炭素成分の存在は確認されなかった。
Comparative Example 5
An active material having the same composition was obtained in the same manner as in Example 5 except that an active material forming solution containing no polyethylene glycol was used. The average particle size of the active material obtained by heating the powder obtained by spraying in a furnace at 400 ° C. over 20 minutes to 400 ° C. in a firing furnace is 18 nm, and spraying in the furnace at 400 ° C. The average particle size of the active material obtained by heating the obtained powder to 600 ° C. for 60 minutes in a heating furnace was 15 nm. As a result of observing the obtained active material using a transmission electron microscope (TEM), the presence of a carbon component in the electrode active material was not confirmed.
実施例６
酢酸リチウム二水和物１０．２ｇ、チタンジイソプロポキシビス（トリエタノールアミネート）（マツモト交商社製チタン錯体、商品名ＴＣ４００：熱分解開始温度３００℃）５８．４ｇを、水：メチルアルコール（２：１）混合溶媒１２０ｇに添加し、更にポリエチレンオキサイド（住友精化株式会社製、ＰＥＯ１：ＴＣ４００の熱分解開始温度における加熱重量減少率９１重量％）２ｇを加え、７０℃にてバイオシェーカーにより回転数２００ｒｐｍで５時間攪拌し、その後、２時間室温で保持したものを活物質形成溶液とした。この活物質形成溶液を、酸素９９．９９％ガスでパージした４００℃に加熱した炉内にスプレー装置（ノードソン社製）により噴霧して粉体を得た。得られた粉体を冷却した後、酸素９９．９９％ガスでパージした焼成炉に入れ、５００℃まで２０分かけて昇温した後、焼成炉から取り出し、平均粒径３１ｎｍの粉末を得た。同様の活物質形成溶液を、同様にして４００℃に加熱した炉内にスプレー装置（ノードソン社製）により噴霧して得た粉体を、冷却後、焼成炉内で６００℃まで２０分かけて昇温加熱した後、冷却し、平均粒径１３０ｎｍの粉体を得た。これらの粉体はＸ線回折により、Ｌｉ４Ｔｉ５Ｏ１２で示される活物質であることが確認された。得られた活物質を、透過型電子顕微鏡（ＴＥＭ）を用いて観察した結果、電極活物質中に炭素成分の存在が確認された。
Example 6
10.4 g of lithium acetate dihydrate, 58.4 g of titanium diisopropoxybis (triethanolaminate) (Titanium complex manufactured by Matsumoto Trading Co., Ltd., trade name TC400: thermal decomposition start temperature 300 ° C.), water: methyl alcohol ( 2: 1) Add to 120 g of mixed solvent, and add 2 g of polyethylene oxide (Sumitomo Seika Chemicals Co., Ltd., PEO1: 91% by weight reduction in heating weight at the thermal decomposition start temperature of TC400), and use a bioshaker at 70 ° C. An active material forming solution was stirred at 200 rpm for 5 hours and then held at room temperature for 2 hours. This active material forming solution was sprayed by a spray device (manufactured by Nordson) into a furnace heated to 400 ° C. purged with 99.99% oxygen gas to obtain a powder. After cooling the obtained powder, it was put into a firing furnace purged with 99.99% oxygen gas, heated to 500 ° C. over 20 minutes, and then taken out from the firing furnace to obtain a powder having an average particle diameter of 31 nm. . A powder obtained by spraying the same active material forming solution in a furnace similarly heated to 400 ° C. with a spray device (manufactured by Nordson) is cooled and then heated to 600 ° C. in a baking furnace over 20 minutes. After heating at an elevated temperature, it was cooled to obtain a powder having an average particle size of 130 nm. These powders were confirmed by X-ray diffraction to be an active material represented by Li 4 Ti 5 O 12 . As a result of observing the obtained active material using a transmission electron microscope (TEM), the presence of a carbon component was confirmed in the electrode active material.
比較例６
ポリエチレンオキサイドを含まない活物質形成溶液を用いた他は、実施例６と同様にして同様の組成の活物質を得た。４００℃の炉内で噴霧して得た粉体を、焼成炉内で５００℃まで２０分かけて昇温加熱して得た活物質の平均粒径は１８ｎｍであり、４００℃の炉内で噴霧して得た粉体を、６００℃まで２０分かけて昇温加熱して得た活物質の平均粒径は２０ｎｍであった。得られた活物質を、透過型電子顕微鏡（ＴＥＭ）を用いて観察した結果、電極活物質中に炭素成分の存在は確認されなかった。
Comparative Example 6
An active material having the same composition was obtained in the same manner as in Example 6 except that an active material forming solution containing no polyethylene oxide was used. The average particle size of the active material obtained by heating the powder obtained by spraying in a furnace at 400 ° C. over 20 minutes in a baking furnace to 500 ° C. is 18 nm. The average particle size of the active material obtained by heating the powder obtained by spraying to 600 ° C. over 20 minutes was 20 nm. As a result of observing the obtained active material using a transmission electron microscope (TEM), the presence of a carbon component in the electrode active material was not confirmed.
実施例７
酢酸リチウム二水和物１０．２ｇ、硝酸コバルト（ＩＩ）六水和物（熱分解開始温度２００℃）２９ｇを、水１００ｇとメチルアルコール２０ｇを混合した混合溶媒に添加し、更にポリエチレングリコール４００（関東化学社製：硝酸コバルトの熱分解開始温度における加熱重量減少率９５重量％）２０ｇを加え、バイオシェーカーにより回転数２００ｒｐｍで７０℃にて５時間攪拌し、その後、２時間室温で保持したものを活物質形成溶液とした。この活物質形成溶液をるつぼに入れ、大気圧雰囲気の焼成炉中で、室温から１時間かけて２００℃に昇温し、２００℃で１時間保持した。次いで、５５０℃まで１時間かけて昇温した後、６０℃まで冷却して平均粒径３１０ｎｍの粉体を得た。上記と同様の活物質形成溶液を同様にして焼成炉内で室温から１時間かけて２００℃に昇温し、２００℃で１時間保持した後、６００℃まで１時間かけて昇温した後、６０℃まで冷却して平均粒径４８０ｎｍの粉体を得た。これらの粉体をＸ線回折測定したところ、いずれもＬｉＣｏＯ２で示される活物質であることが確認された。得られた活物質を、透過型電子顕微鏡（ＴＥＭ）を用いて観察した結果、電極活物質中に炭素成分の存在が確認された。
Example 7
10.2 g of lithium acetate dihydrate and 29 g of cobalt (II) nitrate hexahydrate (thermal decomposition start temperature 200 ° C.) are added to a mixed solvent in which 100 g of water and 20 g of methyl alcohol are mixed, and further, polyethylene glycol 400 ( 20 g of Kanto Chemical Co., Inc .: heating weight reduction rate at the thermal decomposition start temperature of cobalt nitrate (95% by weight), stirred for 5 hours at 70 ° C. with a bioshaker at 200 rpm, and then kept at room temperature for 2 hours Was used as an active material forming solution. This active material forming solution was put into a crucible, heated from room temperature to 200 ° C. over 1 hour in a firing furnace under atmospheric pressure, and held at 200 ° C. for 1 hour. Subsequently, after heating up to 550 degreeC over 1 hour, it cooled to 60 degreeC and obtained powder with an average particle diameter of 310 nm. The same active material forming solution as above was similarly heated in a baking furnace from room temperature to 200 ° C. over 1 hour, held at 200 ° C. for 1 hour, then heated to 600 ° C. over 1 hour, Cooling to 60 ° C. gave a powder with an average particle size of 480 nm. When these powders were measured by X-ray diffraction, it was confirmed that all of them were active materials represented by LiCoO 2 . As a result of observing the obtained active material using a transmission electron microscope (TEM), the presence of a carbon component was confirmed in the electrode active material.
比較例７
ポリエチレングリコールを含まない活物質形成溶液を用いた他は、実施例７と同様にして同様の組成の活物質を得た。２００℃で１時間保持した後、５５０℃まで１時間かけて昇温加熱して得た活物質の平均粒径は２４ｎｍであり、２００℃で１時間保持した後、６００℃まで１時間かけて昇温加熱して得た活物質の平均粒径は３０ｎｍであった。得られた活物質を、透過型電子顕微鏡（ＴＥＭ）を用いて観察した結果、電極活物質中に炭素成分の存在は確認されなかった。
Comparative Example 7
An active material having the same composition was obtained in the same manner as in Example 7 except that an active material forming solution containing no polyethylene glycol was used. After holding at 200 ° C. for 1 hour, the average particle size of the active material obtained by heating to 550 ° C. over 1 hour is 24 nm. After holding at 200 ° C. for 1 hour, it takes 1 hour to 600 ° C. over 1 hour. The average particle size of the active material obtained by heating at an elevated temperature was 30 nm. As a result of observing the obtained active material using a transmission electron microscope (TEM), the presence of a carbon component in the electrode active material was not confirmed.
実施例８
酢酸リチウム二水和物１０．２ｇ、硝酸コバルト（ＩＩ）六水和物（熱分解開始温度２００℃）２９ｇを、水７０ｇとメチルアルコール７０ｇを混合した混合溶媒に添加し、更にアクリル樹脂（共栄社化学製、オリコックスＫＣ：酢酸マンガンの熱分解開始温度における加熱重量減少率６重量％）の５重量％イソプロピルアルコール溶液５０ｇを加え、バイオシェーカーにより回転数２００ｒｐｍで７０℃にて５時間攪拌し、その後、２時間室温で保持したものを活物質形成溶液とした。この活物質形成溶液をるつぼに入れ、大気圧雰囲気の焼成炉中で、室温から１時間かけて２００℃に昇温し、２００℃で１時間保持した。次いで、３９０℃まで１時間かけて昇温した後、６０℃まで冷却して平均粒径１２９ｎｍの粉体を得た。上記と同様の活物質形成溶液を同様にして焼成炉内で室温から１時間かけて２００℃に昇温し、２００℃で１時間保持した後、６００℃まで１時間かけて昇温した後、６０℃まで冷却して平均粒径３７３ｎｍの粉体を得た。これらの粉体をＸ線回折測定したところ、いずれもＬｉＣｏＯ２で示される活物質であることが確認された。得られた活物質を、透過型電子顕微鏡（ＴＥＭ）を用いて観察した結果、電極活物質中に炭素成分の存在が確認された。
Example 8
10.2 g of lithium acetate dihydrate and 29 g of cobalt (II) nitrate hexahydrate (thermal decomposition start temperature 200 ° C.) were added to a mixed solvent in which 70 g of water and 70 g of methyl alcohol were mixed, and acrylic resin (Kyoeisha) 50 g of a 5 wt% isopropyl alcohol solution of Chemical Co., Oricox KC: 6 wt% heating weight reduction rate at the thermal decomposition start temperature of manganese acetate), and stirred at 70 ° C. for 5 hours with a bioshaker at a rotation speed of 200 rpm, Then, what was hold | maintained at room temperature for 2 hours was made into the active material formation solution. This active material forming solution was put into a crucible, heated from room temperature to 200 ° C. over 1 hour in a firing furnace under atmospheric pressure, and held at 200 ° C. for 1 hour. Subsequently, after heating up to 390 degreeC over 1 hour, it cooled to 60 degreeC and obtained powder with an average particle diameter of 129 nm. The same active material forming solution as above was similarly heated in a baking furnace from room temperature to 200 ° C. over 1 hour, held at 200 ° C. for 1 hour, then heated to 600 ° C. over 1 hour, Cooling to 60 ° C. gave a powder with an average particle size of 373 nm. When these powders were measured by X-ray diffraction, it was confirmed that all of them were active materials represented by LiCoO 2 . As a result of observing the obtained active material using a transmission electron microscope (TEM), the presence of a carbon component was confirmed in the electrode active material.
比較例８
アクリル樹脂を含まない活物質形成溶液を用いた他は、実施例８と同様にして同様の組成の活物質を得た。２００℃で１時間保持した後、３９０℃まで１時間かけて昇温加熱して得た活物質の平均粒径は２７ｎｍであり、２００℃で１時間保持した後、６００℃まで１時間かけて昇温加熱して得た活物質の平均粒径は２７ｎｍであった。得られた活物質を、透過型電子顕微鏡（ＴＥＭ）を用いて観察した結果、電極活物質中に炭素成分の存在は確認されなかった。
Comparative Example 8
An active material having the same composition was obtained in the same manner as in Example 8 except that an active material forming solution containing no acrylic resin was used. After maintaining at 200 ° C. for 1 hour, the average particle size of the active material obtained by heating to 390 ° C. over 1 hour is 27 nm. After holding at 200 ° C. for 1 hour, it takes 600 hours to 600 ° C. over 1 hour. The average particle size of the active material obtained by heating at elevated temperature was 27 nm. As a result of observing the obtained active material using a transmission electron microscope (TEM), the presence of a carbon component in the electrode active material was not confirmed.
実施例１〜８、比較例１〜８で得た各活物質粉末を活物質層とする非水電解液二次電池正極用電極板を用い、三極コインセルを作成して充放電試験をおこなった。 Using the electrode plates for a non-aqueous electrolyte secondary battery positive electrode having each active material powder obtained in Examples 1 to 8 and Comparative Examples 1 to 8 as an active material layer, a tripolar coin cell was created and a charge / discharge test was performed. It was.
（正極用電極板の作製）
活物質粉末８０重量部、導電剤としてアセチレンブラック（電気化学工業社製、デンカブラック）１０重量部、結着材としてＰＶＤＦ（クレハ社製、ＫＦ＃１１００）１０重量部に、有機溶媒であるＮＭＰ（三菱化学社製）を加えて分散させ、固形分濃度が５５重量％となるようにエクセルオートホモジナイザー（株式会社日本精機製作所製）にて７０００ｒｐｍで１５分間攪拌し、スラリー状の正極活物質層形成用塗工組成物を調製した。厚さ１５μｍのアルミ箔上に、上記正極活物質層形成用塗工組成物を、１Ｃ放電が１．２ｍＡとなるような塗工量で塗布した後、１２０℃のオーブン中で２０分間乾燥させ、アルミ箔の表面に正極活物質層を形成した。正極活物質層を７ＫＮの圧力でプレスした後、直径１５ｍｍの円板状に裁断し、１２０℃で１２時間、真空乾燥させたものを非水電解液二次電池正極用の電極板とした。
(Preparation of positive electrode plate)
NMP which is an organic solvent in 80 parts by weight of active material powder, 10 parts by weight of acetylene black (manufactured by Denki Black, Denka Black) as a conductive agent, and 10 parts by weight of PVDF (manufactured by Kureha, KF # 1100) as a binder (Mitsubishi Chemical Co., Ltd.) was added and dispersed, and the mixture was stirred for 15 minutes at 7000 rpm with an Excel auto homogenizer (manufactured by Nippon Seiki Seisakusyo Co., Ltd.) so that the solid content concentration was 55% by weight. A forming coating composition was prepared. On the aluminum foil having a thickness of 15 μm, the above-mentioned coating composition for forming a positive electrode active material layer was applied at a coating amount so that 1 C discharge becomes 1.2 mA, and then dried in an oven at 120 ° C. for 20 minutes. A positive electrode active material layer was formed on the surface of the aluminum foil. The positive electrode active material layer was pressed at a pressure of 7 KN, cut into a disk shape having a diameter of 15 mm, and vacuum-dried at 120 ° C. for 12 hours to obtain an electrode plate for a nonaqueous electrolyte secondary battery positive electrode.
（三極コインセルの作製）
エチレンカーボネート／ジメチルカーボネート混合溶媒（体積比１：１）に、溶質として六フッ化リン酸リチウムを加え、溶質濃度１ｍｏｌ／Ｌの非水電解液を調製した。この非水電解液を用いて、上記電極板を作用極板、対極板および参照極板を金属リチウム板とした三極コインセルを組み立て、充放電試験を行った。
(Production of tripolar coin cell)
Lithium hexafluorophosphate was added as a solute to an ethylene carbonate / dimethyl carbonate mixed solvent (volume ratio 1: 1) to prepare a nonaqueous electrolytic solution having a solute concentration of 1 mol / L. Using this non-aqueous electrolyte, a three-pole coin cell was assembled using the electrode plate as a working electrode plate, the counter electrode plate and the reference electrode plate as a metal lithium plate, and a charge / discharge test was conducted.
（充電試験）
上記、三極コインセルを、まず満充電させた。コインセルの充電は、２５℃の環境下でコインセルの電圧が４．３Ｖに達するまで定電流（１．２ｍＡ）をかける定電流充電を行い、電圧が４．３Ｖに達した後は、電圧が４．３Ｖを上回らないように電流（放電レート：１Ｃ）が５％以下となるまで減らして定電圧充電を行い、満充電させた後、１０分間休止させた。尚、上記「放電レート：１Ｃ」とは、上記三極式コインセルを用いて定電流放電して、１時間で放電終了となる電流値（放電終止電圧に達する電流値）のことを意味する。また上記定電流は、コインセルにおける作用極において、活物質の理論放電量が１時間で放電されるよう設定された。
(Charge test)
The tripolar coin cell was first fully charged. The coin cell is charged by performing constant current charging in which a constant current (1.2 mA) is applied until the voltage of the coin cell reaches 4.3 V in an environment of 25 ° C. After the voltage reaches 4.3 V, the voltage becomes 4 The current (discharge rate: 1C) was reduced to 5% or less so as not to exceed 3 V, and constant voltage charging was performed. After the battery was fully charged, it was paused for 10 minutes. The “discharge rate: 1C” means a current value (current value that reaches the discharge end voltage) at which the constant current discharge is performed using the tripolar coin cell and the discharge is completed in one hour. The constant current was set such that the theoretical discharge amount of the active material was discharged in one hour at the working electrode in the coin cell.
（放電試験）
満充電されたコインセルを、２５℃の環境下で、電圧が４．３Ｖ（満充電電圧）から３．０Ｖ（放電終止電圧）になるまで、定電流（１．２ｍＡ）（放電レート：１Ｃ）で定電流放電し、縦軸にセル電圧（Ｖ）、横軸に放電時間（ｈ）をとり、放電曲線を作成し、作用極（正極用電極板）の放電容量（ｍＡｈ）を求め、当該作用極の単位重量当たりの放電容量（ｍＡｈ／ｇ）に換算した。
(Discharge test)
A fully charged coin cell is kept at a constant current (1.2 mA) (discharge rate: 1 C) until the voltage changes from 4.3 V (full charge voltage) to 3.0 V (discharge end voltage) in an environment of 25 ° C. The cell voltage (V) is taken on the vertical axis, the discharge time (h) is taken on the horizontal axis, a discharge curve is created, and the discharge capacity (mAh) of the working electrode (positive electrode plate) is obtained. The discharge capacity (mAh / g) per unit weight of the working electrode was converted.
（サイクル試験）
上述の通り実施した定電流（１．２ｍＡ）（放電レート：１Ｃ、放電終了時間：１時間）での定電流放電試験を５００回繰り返し、その放電容量（ｍＡｈ）の維持率を算出した。実施例１〜４、比較例１〜４の結果を表１に、実施例５〜８、比較例５〜８の結果を表２にそれぞれ示す。
(Cycle test)
The constant current discharge test at a constant current (1.2 mA) (discharge rate: 1 C, discharge end time: 1 hour) carried out as described above was repeated 500 times, and the discharge capacity (mAh) retention rate was calculated. The results of Examples 1 to 4 and Comparative Examples 1 to 4 are shown in Table 1, and the results of Examples 5 to 8 and Comparative Examples 5 to 8 are shown in Table 2, respectively.
本発明は、リチウムイオン二次電池等の非水電解液二次電池の電極に用いられる電極活物質およびその製造方法に関する。 The present invention relates to an electrode active material used for an electrode of a non-aqueous electrolyte secondary battery such as a lithium ion secondary battery and a method for producing the same .
即ち本発明は、
（１）アルカリ金属と、遷移金属とを含むアルカリ遷移金属複合化合物粒子の内部に、エーテル基含有化合物、エステル基含有化合物、カルボキシル基含有化合物、アセチレン系化合物、及びセルロース系化合物より選ばれた１種又は２種以上の炭素成分が存在していることを特徴とする電極活物質、
（２）アルカリ金属化合物と、遷移金属化合物と、セルロース系化合物、ポリアルキレングリコール、アクリル系樹脂、ウレタン系樹脂、エポキシ系樹脂、フェノール系樹脂、メラミン系樹脂、ポリ酢酸ビニル、ポリエチレン、ポリプロピレン、ポリエーテルより選ばれた、遷移金属化合物の熱分解開始温度における加熱重量減少率が１００重量％未満である高分子物質とを含む活物質形成溶液を、遷移金属化合物の熱分解温度以上の温度に加熱し、アルカリ金属と遷移金属とを含むアルカリ遷移金属複合化合物粒子内部に、エーテル基含有化合物、エステル基含有化合物、カルボキシル基含有化合物、アセチレン系化合物、及びセルロース系化合物より選ばれた１種又は２種以上の炭素成分を含有する電極活物質を得ることを特徴とする電極活物質の製造方法、
（３）アルカリ金属化合物と、遷移金属化合物と、前記遷移金属化合物の熱分解開始温度における加熱重量減少率が１００重量％未満である高分子物質とを含む活物質形成溶液を、前記遷移金属化合物の熱分解温度以上の温度に加熱する際に、
加熱終了後にも高分子物質の加熱重量減少率が１００重量％とならないような加熱条件を選択するか、
設定した加熱条件において加熱終了後に加熱重量減少率が１００重量％とならない高分子物質を選択するか、あるいは
設定した加熱条件での加熱終了後に加熱重量減少率が１００重量％とならないように過剰の高分子物質を添加することで、
活物質中に高分子物質あるいは高分子物質の分解物が炭素成分として残存することを特徴とする上記（２）の電極活物質の製造方法、
を要旨とするものである。
That is, the present invention
(1) 1 selected from an ether group-containing compound, an ester group-containing compound, a carboxyl group-containing compound, an acetylene compound, and a cellulose compound inside the alkali transition metal composite compound particles containing an alkali metal and a transition metal An electrode active material characterized in that a seed or two or more carbon components are present,
(2) Alkali metal compounds, transition metal compounds, cellulose compounds, polyalkylene glycols, acrylic resins, urethane resins, epoxy resins, phenol resins, melamine resins, polyvinyl acetate, polyethylene, polypropylene, poly Heating an active material forming solution selected from ether containing a polymer material having a heating weight reduction rate of less than 100% by weight at the thermal decomposition start temperature of the transition metal compound to a temperature equal to or higher than the thermal decomposition temperature of the transition metal compound One or two selected from an ether group-containing compound, an ester group-containing compound, a carboxyl group-containing compound, an acetylene compound, and a cellulose compound inside the alkali transition metal composite compound particle containing an alkali metal and a transition metal. An electrode active material containing at least a species of carbon component is obtained. A method of manufacturing the active material,
(3) An active material forming solution containing an alkali metal compound, a transition metal compound, and a polymer material having a heating weight reduction rate at a thermal decomposition start temperature of the transition metal compound of less than 100% by weight, the transition metal compound When heating to a temperature above the thermal decomposition temperature of
Select a heating condition such that the heating weight reduction rate of the polymer substance does not become 100% by weight even after the heating is completed,
Select a high molecular weight material whose heating weight loss rate does not become 100% by weight after heating under the set heating conditions, or
By adding an excessive polymer substance so that the heating weight reduction rate does not become 100% by weight after the heating under the set heating conditions,
The method for producing an electrode active material according to (2) above, wherein the polymer material or a decomposition product of the polymer material remains as a carbon component in the active material,
Is a summary.
本発明の電極活物質は、アルカリ金属化合物と、遷移金属化合物と、高分子物質とを含む活物質形成溶液を、遷移金属化合物の熱分解開始温度以上の温度で加熱することにより得られるアルカリ遷移金属複合化合物粒子の内部に、炭素成分が存在している活物質である。アルカリ金属化合物としては、リチウム、ナトリウム等のアルカリ金属の塩化物、硝酸塩、硫酸塩、過塩素酸塩、酢酸塩、リン酸塩、臭素酸塩等が用いられる。なかでも入手が容易な塩化物、硝酸塩、酢酸塩が好ましい。具体的なリチウム化合物としては、例えばクエン酸リチウム四水和物、過塩素酸リチウム三水和物、酢酸リチウム二水和物、硝酸リチウム、リン酸リチウム等が挙げられ、ナトリウム化合物としては、例えば硝酸ナトリウム、酢酸ナトリウム等が挙げられる。アルカリ金属化合物は、１種又は２種以上を併用することができる。 The electrode active material of the present invention is an alkali transition obtained by heating an active material forming solution containing an alkali metal compound, a transition metal compound, and a polymer material at a temperature equal to or higher than the thermal decomposition start temperature of the transition metal compound. It is an active material in which a carbon component is present inside the metal composite compound particles. Examples of the alkali metal compound include chlorides, nitrates, sulfates, perchlorates, acetates, phosphates, bromates, and the like of alkali metals such as lithium and sodium. Of these, chlorides, nitrates, and acetates that are readily available are preferred. Specific lithium compounds include, for example, lithium citrate tetrahydrate, lithium perchlorate trihydrate, lithium acetate dihydrate, lithium nitrate, lithium phosphate and the like, and sodium compounds include, for example, Examples thereof include sodium nitrate and sodium acetate. One or more alkali metal compounds can be used in combination.
アルカリ金属化合物の熱分解開始温度は、遷移金属化合物の熱分解開始温度よりも高い温度であるが、高分子物質が存在していることにより、アルカリ金属化合物の熱分解開始温度よりも低い温度であっても、遷移金属化合物の熱分解開始温度以上の温度で加熱しても活物質を得ることができる。また、活物質形成溶液中に、遷移金属化合物の熱分解開始温度における加熱重量減少率が１００重量％未満の高分子物質が共存していることにより、活物質形成溶液を遷移金属化合物の熱分解開始温度以上に加熱した際に、高分子物質に活物質結晶の成長が阻害されるために微細な結晶が生成し、この微細結晶が更に加熱した際に成長することで、より大きな粒径の活物質が得られると考えられる。本発明において上記遷移金属化合物の熱分解開始温度とは、遷移金属化合物を１２０℃で１０分保持した後、１０℃／分の速度で昇温加熱した時に、５重量％の重量減少が生じた時の温度とする。熱分解開始温度は、遷移金属化合物を熱天秤により昇温加熱して測定することができる。また高分子物質の加熱重量変化率は、高分子物質を１０℃／分の速度で昇温加熱して遷移金属化合物の熱分解開始温度に達した時の重量の、元の重量に対する重量変化率として求めることができる。高分子物質の加熱重量変化は、熱天秤により高分子物質を昇温加熱した際の重量変化を測定することで求めることができる。尚、複数の遷移金属化合物を併用する場合、各遷移金属化合物の熱分解開始温度のうち、最も低い温度を遷移金属化合物の熱分解開始温度として採用する。 The thermal decomposition start temperature of the alkali metal compound is higher than the thermal decomposition start temperature of the transition metal compound. However, due to the presence of the polymer substance , the thermal decomposition start temperature is lower than the thermal decomposition start temperature of the alkali metal compound. Even in such a case, the active material can be obtained by heating at a temperature equal to or higher than the thermal decomposition start temperature of the transition metal compound. In addition, the active material forming solution is thermally decomposed of the transition metal compound by the coexistence of a polymer material having a heating weight reduction rate of less than 100% by weight at the thermal decomposition starting temperature of the transition metal compound. When heated above the starting temperature, the growth of active material crystals is hindered by the polymer material, resulting in the formation of fine crystals, and the fine crystals grow when heated further, resulting in a larger particle size. It is thought that an active material is obtained. In the present invention, the thermal decomposition start temperature of the transition metal compound means that the transition metal compound was held at 120 ° C. for 10 minutes and then heated at a rate of 10 ° C./min. The temperature of the hour. The thermal decomposition starting temperature can be measured by heating the transition metal compound with a thermobalance. Further, the weight change rate of the polymer material by weight is the weight change rate of the weight when the polymer material is heated at a rate of 10 ° C./min to reach the thermal decomposition start temperature of the transition metal compound relative to the original weight. Can be obtained as The change in weight of the polymer material by heating can be determined by measuring the change in weight when the polymer material is heated by heating using a thermobalance. In addition, when using a some transition metal compound together, the lowest temperature is employ | adopted as the thermal decomposition start temperature of a transition metal compound among the thermal decomposition start temperatures of each transition metal compound.
実施例１
酢酸リチウム二水和物１０．２ｇ、硝酸鉄（ＩＩＩ）九水和物（熱分解開始温度１８０℃）４０．４ｇ、リン酸９．８ｇ、メチルセルロース（信越化学株式会社製、メトローズ６５ＳＨ−１５００：硝酸鉄の熱分解開始温度における加熱重量減少率６重量％）２ｇを、水１００ｇ、メチルアルコール４５ｇの混合溶媒に添加し、バイオシェーカーにより回転数２００ｒｐｍで７０℃にて１時間攪拌して活物質形成溶液を調製した。この溶液をるつぼに入れ、４％の水素を含んだ窒素ガスでパージした焼成炉中で、室温から１時間かけて２００℃に昇温し、同温度で１時間保持した。次いで、３８０℃まで２０分かけて昇温した後、窒素ガスをパージしながら６０℃まで冷却し、平均粒径３５ｎｍの粉体を得た。この粉体はＸ線回折測定により、ＬｉＦｅＰＯ４で示される活物質であることが確認された。得られた活物質を、透過型電子顕微鏡（ＴＥＭ）を用いて観察した結果、電極活物質中に炭素成分の存在が確認され、ＩＲ測定により、セルロース基に特有の吸収スペクトルを確認した。
比較例１
実施例１と同様の活物質形成溶液を同様にして焼成炉内で室温から１時間かけて２００℃に昇温し、同温度で１時間保持した後、５００℃まで２０分かけて昇温した後、窒素ガスをパージしながら６０℃まで冷却し、平均粒径５７ｎｍの粉体を得た。この粉体はＸ線回折測定により、ＬｉＦｅＰＯ ４ で示される活物質であることが確認された。得られた活物質を、透過型電子顕微鏡（ＴＥＭ）を用いて観察した結果、電極活物質中に炭素成分の存在が確認されたがＩＲによるセルロースに特有な吸収スペクトルは認められなかった。これは、５００℃まで昇温したものでは、セルロース構造が壊れた炭素成分の状態で存在していると推測される。
Example 1
Lithium acetate dihydrate 10.2 g, iron (III) nitrate nonahydrate (thermal decomposition start temperature 180 ° C.) 40.4 g, phosphoric acid 9.8 g, methylcellulose (manufactured by Shin-Etsu Chemical Co., Ltd., Metrose 65SH-1500): 2 g of heating weight reduction rate at the thermal decomposition start temperature of iron nitrate was added to a mixed solvent of 100 g of water and 45 g of methyl alcohol, and the active material was stirred at 70 ° C. for 1 hour at a rotation speed of 200 rpm with a bioshaker. A forming solution was prepared. This solution was put in a crucible, heated from room temperature to 200 ° C. over 1 hour in a firing furnace purged with nitrogen gas containing 4% hydrogen, and kept at that temperature for 1 hour. Subsequently, after heating up to 380 degreeC over 20 minutes, it cooled to 60 degreeC, purging nitrogen gas, and obtained the powder with an average particle diameter of 35 nm . This powder was confirmed to be an active material represented by LiFePO 4 by X-ray diffraction measurement. The obtained active material, the presence of the carbon component is confirmed results observed using a transmission electron microscope (TEM), in the electrodeposition electrode active material, Ri by the IR measurement, absorption peculiar to cellulose based The spectrum was confirmed .
Comparative Example 1
In the same manner, the active material forming solution similar to that in Example 1 was heated from room temperature to 200 ° C. over 1 hour in the baking furnace, held at the same temperature for 1 hour, and then heated to 500 ° C. over 20 minutes. Thereafter, the mixture was cooled to 60 ° C. while purging with nitrogen gas to obtain a powder having an average particle diameter of 57 nm. This powder was confirmed to be an active material represented by LiFePO 4 by X-ray diffraction measurement . As a result of observing the obtained active material using a transmission electron microscope (TEM), the presence of a carbon component was confirmed in the electrode active material, but an absorption spectrum peculiar to cellulose by IR was not recognized. This is presumed that when the temperature is raised to 500 ° C., the cellulose structure is present in a broken carbon component state.
比較例２
メチルセルロースを含まない活物質形成溶液を用いた他は、実施例１と同様にして同様の組成の活物質を得た。２００℃で１時間保持した後、３８０℃まで２０分かけて昇温加熱して得た活物質の平均粒径は１６ｎｍであり、２００℃で１時間保持した後、５００℃まで２０分℃まで昇温加熱して得た活物質の平均粒径は１５ｎｍであった。得られた活物質を、透過型電子顕微鏡（ＴＥＭ）を用いて観察した結果、電極活物質中に炭素成分の存在は確認されなかった。
Comparative Example 2
An active material having the same composition was obtained in the same manner as in Example 1 except that an active material forming solution not containing methylcellulose was used. After holding at 200 ° C. for 1 hour, the average particle size of the active material obtained by heating up to 380 ° C. over 20 minutes is 16 nm. After holding at 200 ° C. for 1 hour, it reaches 500 ° C. up to 20 minutes. The average particle size of the active material obtained by heating at elevated temperature was 15 nm. As a result of observing the obtained active material using a transmission electron microscope (TEM), the presence of a carbon component in the electrode active material was not confirmed.
実施例１、比較例１、２で得た各活物質粉末を活物質層とする非水電解液二次電池正極用電極板を用い、三極コインセルを作成して充放電試験をおこなった。 Using a non-aqueous electrolyte secondary battery positive electrode plate having the active material powder obtained in Example 1, Comparative Example 1 and 2 as an active material layer, a tripolar coin cell was prepared and a charge / discharge test was performed.
（サイクル試験）
上述の通り実施した定電流（１．２ｍＡ）（放電レート：１Ｃ、放電終了時間：１時間）での定電流放電試験を５００回繰り返し、その放電容量（ｍＡｈ）の維持率を算出した。実施例１、比較例１、２の結果を表１に示す。
(Cycle test)
The constant current discharge test at a constant current (1.2 mA) (discharge rate: 1 C, discharge end time: 1 hour) carried out as described above was repeated 500 times, and the discharge capacity (mAh) retention rate was calculated. Table 1 shows the results of Example 1 and Comparative Examples 1 and 2 .
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