TWI453979B - A lithium ion battery positive electrode active material, positive electrode for a lithium ion battery, and a lithium ion battery - Google Patents

Description

鋰離子電池用正極活性物質、鋰離子電池用正極、及鋰離子電池Positive electrode active material for lithium ion battery, positive electrode for lithium ion battery, and lithium ion battery

本發明係關於一種鋰離子電池用正極活性物質、鋰離子電池用正極、及鋰離子電池。The present invention relates to a positive electrode active material for a lithium ion battery, a positive electrode for a lithium ion battery, and a lithium ion battery.

鋰離子電池之正極活性物質，通常使用含鋰之過渡金屬氧化物。具體而言，為鈷酸鋰(LiCoO₂ )、鎳酸鋰(LiNiO₂ )、錳酸鋰(LiMn₂ O₄ )等，為了改善特性(高容量化、循環特性、保存特性、降低內部電阻、比率(rate)特性)或提高安全性，而不斷對該等進行複合化。對於車輛用或負載調平(load leveling)用等大型用途中之鋰離子電池，謀求與至今為止之行動電話用或個人電腦用不同之特性。For the positive electrode active material of a lithium ion battery, a lithium-containing transition metal oxide is usually used. Specifically, it is lithium cobaltate (LiCoO ₂ ), lithium nickelate (LiNiO ₂ ), lithium manganate (LiMn ₂ O ₄ ), etc., in order to improve characteristics (high capacity, cycle characteristics, storage characteristics, internal resistance reduction, Rate characteristics) or improve security, and constantly compositing them. For lithium-ion batteries in large-scale applications such as vehicles or load leveling, they are designed to have different characteristics from those used in mobile phones or personal computers.

為了改善電池特性，先前使用各種方法，例如於專利文獻1中揭示有一種下述鋰二次電池用正極材料之製造方法，其特徵在於：將以Li_x Ni_1-y M_y O_2-δ In order to improve battery characteristics, various methods have been previously used, for example, Patent Document 1 discloses a method for producing a positive electrode material for a lithium secondary battery, which is characterized in that Li _x Ni _1-y M _y O _2-δ

(0.8≦x≦1.3，0<y≦0.5，M表示選自由Co、Mn、Fe、Cr、V、Ti、Cu、Al、Ga、Bi、Sn、Zn、Mg、Ge、Nb、Ta、Be、B、Ca、Sc及Zr所組成之群中的至少一種元素，δ相當於氧欠缺或氧過剩量，表示-0.1<δ<0.1)之組成所示的鋰鎳複合氧化物通過分級機，以平衡分離粒徑Dh=1~10μm分離成粒徑較大者與較小者，以重量比為0：100~100：0摻合粒徑較大者與較小者。並且，記載有若根據該方法，即可輕易製造比率特性與容量各項平衡的鋰二次 電池用正極材料。(0.8≦x≦1.3,0<y≦0.5, M means selected from Co, Mn, Fe, Cr, V, Ti, Cu, Al, Ga, Bi, Sn, Zn, Mg, Ge, Nb, Ta, Be At least one element selected from the group consisting of B, Ca, Sc, and Zr, δ corresponds to an oxygen deficiency or an excess amount of oxygen, and the lithium nickel composite oxide represented by the composition of -0.1 < δ < 0.1) passes through a classifier. The equilibrium separation particle diameter Dh=1~10μm is separated into smaller and smaller particles, and the weight ratio is 0:100~100:0, and the smaller the particle size is smaller and smaller. Further, it is described that, according to the method, lithium secondary having a balance between the ratio characteristics and the capacity can be easily produced. Positive electrode material for battery.

[專利文獻1]日本特許第4175026號公報[Patent Document 1] Japanese Patent No. 4175526

專利文獻1中記載之鋰鎳複合氧化物係其組成式中之氧量過剩者，但即便如此，對於作為高品質之鋰離子電池用正極活性物質而言，仍然具有改善之餘地。The lithium-nickel composite oxide described in Patent Document 1 is one in which the amount of oxygen in the composition formula is excessive. However, there is still room for improvement in the high-quality positive electrode active material for lithium ion batteries.

因此，本發明之課題在於，提供一種具有良好電池特性之鋰離子電池用正極活性物質。Therefore, an object of the present invention is to provide a positive electrode active material for a lithium ion battery having good battery characteristics.

本發明人經潛心研究，結果發現正極活性物質之氧量及一次粒子的粒徑與電池特性之間存在緊密之相關關係。即，發現將正極活性物質之氧量設為某數值以上，且將正極活性物質之一次粒子的粒徑控制於適當的範圍，藉此可獲得良好之電池特性。As a result of intensive research, the present inventors have found that there is a close correlation between the amount of oxygen of the positive electrode active material and the particle size of the primary particles and the battery characteristics. In other words, it has been found that the amount of oxygen of the positive electrode active material is equal to or greater than a certain value, and the particle diameter of the primary particles of the positive electrode active material is controlled to an appropriate range, whereby good battery characteristics can be obtained.

並且發現正極活性物質的碳含量及正極活性物質的粒子表面之殘留鹼即碳酸鋰量，與電池特性之間具有密切的相關關係。即，發現當正極活性物質的碳含量在某數值以下時，又，當正極活性物質的粒子表面之碳酸鋰量在某數值以下時，可得到特別良好的電池特性。Further, it was found that the carbon content of the positive electrode active material and the amount of residual alkali, that is, the amount of lithium carbonate, on the surface of the particle of the positive electrode active material have a close correlation with the battery characteristics. In other words, when the carbon content of the positive electrode active material is below a certain value, it is found that when the amount of lithium carbonate on the surface of the particle of the positive electrode active material is below a certain value, particularly excellent battery characteristics can be obtained.

以上述見解為基礎而完成之本發明，於一態樣中為一種鋰離子電池用正極活性物質，其係以下述組成式表示：Li_x Ni_1-y M_y O_2+α The present invention based on the above findings is, in one aspect, a positive electrode active material for a lithium ion battery, which is represented by the following composition formula: Li _x Ni _1-y M _y O _{2+ α}

(上述式中，M為選自Sc、Ti、V、Cr、Mn、Fe、Co、Cu、Zn、Ga、Ge、Bi、Sn、Mg、Ca、B及Zr中之1種以上，0.9≦x≦1.2，0<y≦0.7，α>0.1)，一次粒子之粒徑 為1.6~2.3μm，利用LECO法測定之碳量為0.40質量%以下，利用中和滴定所測定之粒子表面的殘留鹼即碳酸鋰量為0.70質量%以下。(In the above formula, M is one or more selected from the group consisting of Sc, Ti, V, Cr, Mn, Fe, Co, Cu, Zn, Ga, Ge, Bi, Sn, Mg, Ca, B, and Zr, 0.9≦ X≦1.2,0<y≦0.7,α>0.1), particle size of primary particles The amount of carbon measured by the LECO method is 0.40% by mass or less, and the amount of lithium carbonate, which is a residual alkali on the surface of the particles measured by the neutralization titration, is 0.70% by mass or less.

本發明之鋰離子電池用正極活性物質，於一實施形態中，利用LECO法測定之碳量為0.20質量%以下，利用中和滴定所測定之粒子表面的殘留鹼即碳酸鋰量為0.60質量%以下。In one embodiment, the amount of carbon measured by the LECO method is 0.20% by mass or less, and the amount of lithium carbonate, which is a residual alkali on the surface of the particles measured by neutralization titration, is 0.60% by mass. the following.

本發明之鋰離子電池用正極活性物質，於另一實施形態中，M為選自Mn及Co中之1種以上。In another embodiment, the positive electrode active material for a lithium ion battery of the present invention is one or more selected from the group consisting of Mn and Co.

本發明之鋰離子電池用正極活性物質，於再另一實施形態中，組成式中，α>0.15。In still another embodiment of the positive electrode active material for a lithium ion battery of the present invention, in the composition formula, α > 0.15.

本發明之鋰離子電池用正極活性物質，於再另一實施形態中，組成式中，α>0.20。In still another embodiment of the positive electrode active material for a lithium ion battery of the present invention, in the composition formula, α>0.20.

本發明於另一態樣中為一種鋰離子電池用正極，其使用有本發明之鋰離子電池用正極活性物質。In another aspect, the present invention provides a positive electrode for a lithium ion battery using the positive electrode active material for a lithium ion battery of the present invention.

本發明於再另一態樣中為一種鋰離子電池，其使用有本發明之鋰離子電池用正極。In still another aspect, the present invention is a lithium ion battery using the positive electrode for a lithium ion battery of the present invention.

根據本發明，可提供一種具有良好電池特性之鋰離子電池用正極活性物質。According to the present invention, a positive electrode active material for a lithium ion battery having good battery characteristics can be provided.

(鋰離子電池用正極活性物質之構成)(Composition of positive active material for lithium ion battery)

本發明之鋰離子電池用正極活性物質之材料，可廣泛使用適用作為一般鋰離子電池用正極用之正極活性物質的化合物，尤佳使用鈷酸鋰(LiCoO₂ )、鎳酸鋰(LiNiO₂ )、 錳酸鋰(LiMn₂ O₄ )等含鋰之過渡金屬氧化物。使用上述材料製作之本發明之鋰離子電池用正極活性物質係以下述組成式表示：Li_x Ni_1-y M_y O_2+α The material of the positive electrode active material for a lithium ion battery of the present invention can be widely used as a compound for a positive electrode active material for a positive electrode for a general lithium ion battery, and particularly preferably lithium cobaltate (LiCoO ₂ ) or lithium nickelate (LiNiO ₂ ). A lithium-containing transition metal oxide such as lithium manganate (LiMn ₂ O ₄ ). The positive electrode active material for a lithium ion battery of the present invention produced using the above materials is represented by the following composition formula: Li _x Ni _1-y M _y O _{2+ α}

(上述式中，M為選自Sc、Ti、V、Cr、Mn、Fe、Co、Cu、Zn、Ga、Ge、Bi、Sn、Mg、Ca、B及Zr中之1種以上，0.9≦x≦1.2，0<y≦0.7，α>0.1)。(In the above formula, M is one or more selected from the group consisting of Sc, Ti, V, Cr, Mn, Fe, Co, Cu, Zn, Ga, Ge, Bi, Sn, Mg, Ca, B, and Zr, 0.9≦ x≦1.2, 0<y≦0.7, α>0.1).

鋰離子電池用正極活性物質中之鋰相對於全部金屬之比率為0.9~1.2，其係因為若未達0.9則難以保持穩定之結晶結構，超過1.2則變得無法確保電池之高容量。The ratio of lithium to the total metal in the positive electrode active material for a lithium ion battery is 0.9 to 1.2, because if it is less than 0.9, it is difficult to maintain a stable crystal structure, and if it exceeds 1.2, the high capacity of the battery cannot be ensured.

本發明之鋰離子電池用正極活性物質之氧，於組成式中如上述，係表示為O_2+α (α>0.1)，過剩地含有，當用於鋰離子電池之情形時，容量、比率特性及容量保持率等電池特性會變得良好。此處，關於α，較佳為α>0.15，更佳為α>0.20。A lithium ion battery according to the present invention with an oxygen cathode active substances, such as in the above composition formula, based denoted as _{O 2 + α (α> 0.1} ), contained in excess, for the case when a lithium ion battery, the capacity ratio Battery characteristics such as characteristics and capacity retention rate will become good. Here, with respect to α, α is preferably 0.15, more preferably α>0.20.

鋰離子電池用正極活性物質，係由一次粒子、一次粒子凝集而成之二次粒子，或一次粒子及二次粒子之混合物構成(參考圖1)。當中，一次粒子之粒徑為1.6~2.3μm。若一次粒子之粒徑未達1.6μm，則會發生如下問題：引起因在製作電池時之加壓所導致的粒子破裂，或由電池循環時之粒子裂痕所導致的劣化。又，若一次粒子之粒徑超過2.3μm，則會發生如下問題：因電解液乾枯或電解液量增加而導致電池劣化。一次粒子之粒徑較佳為1.8~2.1μm。The positive electrode active material for a lithium ion battery is composed of secondary particles in which primary particles and primary particles are aggregated, or a mixture of primary particles and secondary particles (see FIG. 1). Among them, the primary particles have a particle diameter of 1.6 to 2.3 μm. If the particle diameter of the primary particles is less than 1.6 μm, there arises a problem that the particles are broken due to the pressurization at the time of battery production, or the deterioration caused by the particle cracks when the battery is circulated. Further, when the particle diameter of the primary particles exceeds 2.3 μm, there is a problem that the battery is deteriorated due to dryness of the electrolyte or an increase in the amount of the electrolyte. The particle diameter of the primary particles is preferably from 1.8 to 2.1 μm.

本發明之鋰離子電池用正極活性物質其利用LECO法 測定之碳量為0.40質量%以下。LECO法係惰性氣體溶解-紅外線吸收法，例如於JIS R 1603中有所規定。若正極活性物質的含碳量超過0.40質量%，則使用有該正極活性物質之鋰離子電池的電池特性，特別是循環特性會變得不良。藉由LECO法測定之碳量，較佳為0.30質量%以下，更佳為0.20質量%以下。關於正極材料所含的碳，並非單獨存在於正極材料之粒子內部或表面，而是以碳酸鋰(Li₂ CO₃ )的形式存在。碳酸鋰為弱鹼，會使電池特性下降，故殘留鹼較少為佳。如上所述，於本發明中，所謂「正極活性物質的含碳量」，係表示於正極材料中以碳酸鋰(Li₂ CO₃ )形態含有的碳量，且若此量少(若為0.40質量%以下)，則電池特性會變得良好。The amount of carbon of the positive electrode active material for a lithium ion battery of the present invention measured by the LECO method is 0.40% by mass or less. The LECO method is an inert gas dissolution-infrared absorption method, which is specified, for example, in JIS R 1603. When the carbon content of the positive electrode active material exceeds 0.40% by mass, the battery characteristics of the lithium ion battery having the positive electrode active material are used, and in particular, the cycle characteristics are deteriorated. The amount of carbon measured by the LECO method is preferably 0.30% by mass or less, more preferably 0.20% by mass or less. The carbon contained in the positive electrode material does not exist alone in the interior or surface of the particles of the positive electrode material, but exists in the form of lithium carbonate (Li ₂ CO ₃ ). Lithium carbonate is a weak base, which degrades battery characteristics, so less residual alkali is preferred. As described above, the "carbon content of the positive electrode active material" in the present invention means the amount of carbon contained in the form of lithium carbonate (Li ₂ CO ₃ ) in the positive electrode material, and if the amount is small (if 0.40) The battery characteristics are good if the mass is less than or equal to).

本發明之鋰離子電池用正極活性物質，其藉由中和滴定而測定之粒子表面的殘留鹼即碳酸鋰量為0.70質量%以下。中和滴定係以鹽酸等作為滴定液而使用一般的中和滴定法來進行。若粒子表面的殘留鹼即碳酸鋰量超過0.7質量%，則重覆進行充放電時會與電解液反應，而產生劣化，使電池特性變差。又，若鹼較多，則會產生氣體，而引起電池特性劣化。藉由中和滴定而測定之粒子表面的殘留鹼即碳酸鋰量，較佳為0.60質量%以下，更佳為0.55質量%以下。In the positive electrode active material for a lithium ion battery of the present invention, the amount of lithium carbonate, which is a residual alkali on the surface of the particles measured by neutralization titration, is 0.70% by mass or less. The neutralization titration is carried out by using a normal neutralization titration method using hydrochloric acid or the like as a titration solution. When the amount of lithium carbonate, which is a residual alkali on the surface of the particles, exceeds 0.7% by mass, when it is repeatedly charged and discharged, it reacts with the electrolytic solution to cause deterioration and deteriorates battery characteristics. Further, if a large amount of alkali is generated, a gas is generated and the battery characteristics are deteriorated. The amount of lithium carbonate, which is a residual alkali on the surface of the particles measured by neutralization titration, is preferably 0.60% by mass or less, more preferably 0.55% by mass or less.

(鋰離子電池用正極及使用其之鋰離子電池之構成)(Construction of a positive electrode for a lithium ion battery and a lithium ion battery using the same)

本發明之實施形態之鋰離子電池用正極，例如具有下述構造：將混合上述構成之鋰離子電池用正極活性物質、 導電助劑及黏合劑製備而成之正極合劑，設置於由鋁箔等構成之集電體的單面或雙面。又，本發明之實施形態之鋰離子電池，具備有上述構成之鋰離子電池用正極。The positive electrode for a lithium ion battery according to the embodiment of the present invention has a structure in which a positive electrode active material for a lithium ion battery having the above configuration is mixed, The positive electrode mixture prepared by the conductive auxiliary agent and the adhesive is disposed on one side or both sides of the current collector composed of aluminum foil or the like. Moreover, the lithium ion battery according to the embodiment of the present invention includes the positive electrode for a lithium ion battery having the above configuration.

(鋰離子電池用正極活性物質之製造方法)(Method for producing positive electrode active material for lithium ion battery)

其次，詳細說明本發明之實施形態之鋰離子電池用正極活性物質的製造方法。Next, a method for producing a positive electrode active material for a lithium ion battery according to an embodiment of the present invention will be described in detail.

首先，製作金屬鹽溶液。該金屬為Ni，及選自Sc、Ti、V、Cr、Mn、Fe、Co、Cu、Zn、Ga、Ge、Bi、Sn、Mg、Ca、B及Zr中之1種以上。又，金屬鹽為硫酸鹽、氯化物、硝酸鹽、乙酸鹽等，尤佳為硝酸鹽。其原因在於：即便是以雜質的形態混入燒成原料中，亦可直接燒成，故可省去清洗步驟；以及硝酸鹽會作為氧化劑而發揮功能，具有促進燒成原料中之金屬之氧化的作用。預先調整金屬鹽中所含之各金屬成為所欲之莫耳比率。藉此，決定正極活性物質中之各金屬的莫耳比率。First, a metal salt solution is prepared. The metal is Ni and one or more selected from the group consisting of Sc, Ti, V, Cr, Mn, Fe, Co, Cu, Zn, Ga, Ge, Bi, Sn, Mg, Ca, B, and Zr. Further, the metal salt is a sulfate, a chloride, a nitrate, an acetate or the like, and particularly preferably a nitrate. The reason for this is that even if it is mixed into the calcined raw material in the form of impurities, it can be directly calcined, so that the washing step can be omitted, and the nitrate functions as an oxidizing agent, and the oxidation of the metal in the calcining raw material is promoted. effect. The metal contained in the metal salt is adjusted in advance to have a desired molar ratio. Thereby, the molar ratio of each metal in the positive electrode active material is determined.

其次，使碳酸鋰懸浮於純水，然後投入上述金屬之金屬鹽溶液製作金屬碳酸鹽溶液漿料。此時，漿料中會析出微小粒之含鋰碳酸鹽。又，此時，為了將碳酸鋰與金屬鹽溶液混合而進行攪拌，攪拌地愈充分則所生成的漿料粒子就會變得愈小，可更均勻且良好地進行反應、使未反應的碳酸鋰量減少，藉此可抑制所製作之鋰鹽複合體(鋰離子電池正極材料用前驅物)中的碳含量。攪拌條件係使用特定大小的攪拌翼以旋轉數250rpm左右將溶液攪拌。Next, lithium carbonate is suspended in pure water, and then a metal salt solution of the above metal is introduced to prepare a metal carbonate solution slurry. At this time, lithium carbonate containing fine particles is precipitated in the slurry. In addition, in this case, in order to mix the lithium carbonate and the metal salt solution, stirring is performed, and the more the stirring is, the smaller the slurry particles are formed, and the reaction can be performed more uniformly and satisfactorily, and unreacted carbonic acid can be obtained. The amount of lithium is reduced, whereby the carbon content in the produced lithium salt composite (precursor for lithium ion battery positive electrode material) can be suppressed. The stirring condition is to stir the solution by using a stirring blade of a specific size at a rotation number of about 250 rpm.

再者，於作為金屬鹽之硫酸鹽或氯化物等之熱處理時 其鋰化合物不進行反應之情形時，利用飽和碳酸鋰溶液將該等之鹽清洗後進行過濾分離。如硝酸鹽或乙酸鹽，其鋰化合物於熱處理過程中作為鋰原料進行反應之情形時，可不進行清洗，而直接過濾分離並加以乾燥，藉此使用作為前驅物。Furthermore, when heat treatment is used as a metal salt of a sulfate or a chloride When the lithium compound is not reacted, the salt is washed with a saturated lithium carbonate solution and then separated by filtration. For example, when a nitrate compound or an acetate compound is reacted as a lithium raw material during heat treatment, it may be used as a precursor without being washed and directly separated by filtration and dried.

其次，藉由將經過濾分離之含鋰碳酸鹽加以乾燥，而獲得鋰鹽之複合體(鋰離子電池正極材料用前驅物)之粉末。Next, a powder of a lithium salt composite (precursor for a lithium ion battery positive electrode material) is obtained by drying the filtered lithium-containing carbonate.

其次，準備具有特定大小之容量的燒成容器，將鋰離子電池正極材料用前驅物之粉末填充於該燒成容器。其次，將填充有鋰離子電池正極材料用前驅物之粉末的燒成容器搬移至燒成爐，進行燒成。燒成係藉由在氧氣環境下加熱保持特定時間來進行。又，若於101~202KPa之加壓下進行燒成，則由於會進一步增加組成中之氧量，故較佳。Next, a firing vessel having a capacity of a specific size is prepared, and a lithium ion battery positive electrode material is filled in the firing vessel with the powder of the precursor. Next, the firing container filled with the powder of the precursor for the positive electrode material for a lithium ion battery is transferred to a baking furnace and fired. The firing is carried out by heating in an oxygen atmosphere for a specific period of time. Further, if the firing is carried out under a pressure of 101 to 202 KPa, the amount of oxygen in the composition is further increased, which is preferable.

燒成步驟中之加熱保持溫度會對鋰離子電池正極材料之一次粒子的粒徑造成影響。於本發明中，因為於原料中使用有碳酸鋰，故反應性比將氫氧化鋰用作為原料之情形要弱。因此，變得必須於高溫進行長時間燒成，藉由該高溫且長時間之燒成，粒子之結晶性獲得增加且正極材料之一次粒子的粒徑變大。於本發明中，於原料中使用碳酸鋰，並於750℃以上進行12小時以上的燒成，藉此將一次粒子之粒徑控制在1.6~2.3μm。相對於此，於將氫氧化鋰作為原料之情形，通常因為反應性高故降低燒成溫度，且燒成時間變少，因此會造成生成之一次粒子的粒徑變小成0.5μ m左右。The heating and holding temperature in the firing step affects the particle size of the primary particles of the positive electrode material of the lithium ion battery. In the present invention, since lithium carbonate is used as a raw material, reactivity is weaker than when lithium hydroxide is used as a raw material. Therefore, it is necessary to perform baking for a long time at a high temperature, and by the high-temperature and long-time firing, the crystallinity of the particles is increased and the particle diameter of the primary particles of the positive electrode material is increased. In the present invention, lithium carbonate is used as a raw material, and firing is performed at 750 ° C or higher for 12 hours or longer, whereby the particle diameter of the primary particles is controlled to 1.6 to 2.3 μm. On the other hand, when lithium hydroxide is used as a raw material, usually, since the reactivity is high, the firing temperature is lowered, and the firing time is reduced, so that the particle diameter of the generated primary particles is reduced to 0.5 μ. m or so.

然後，自燒成容器取出粉末，使用市售之粉碎裝置等進行粉碎，藉此獲得正極活性物質之粉體。此時之粉碎係以盡量不生成微粉末的方式適當地調整粉碎強度及粉碎時間來進行。具體而言，藉由該粉碎，於將D90設為：累積曲線成為90%之點的粒徑(μm)，將D10設為：累積曲線成為10%之點的粒徑(μm)時，調整成(D90-D10)/2在8μm以下。又，更佳為調整成(D90-D10)/2在6μm以下。粉碎性佳的情形為微粉末發生少，且粗大粉體發生亦少，故D90成為相對較小的值，D10成為相對較大的值。特別是在粉碎性劣化之情形時，容易變成拉出長底邊(出現尾巴)至粒徑小之區域的狀態，若成為此情形，則D10會變成相對地小，其結果(D90-D10)/2變大。亦即，(D90-D10)/2可說是表示粒度不均少之指標。Then, the powder is taken out from the firing container, and pulverized using a commercially available pulverizing apparatus or the like to obtain a powder of the positive electrode active material. The pulverization at this time is carried out by appropriately adjusting the pulverization strength and the pulverization time so as not to generate fine powder as much as possible. Specifically, by the pulverization, D90 is set to a particle diameter (μm) at which the cumulative curve is 90%, and D10 is set to a particle diameter (μm) at which the cumulative curve becomes 10%. Cheng (D90-D10)/2 is below 8 μm. Further, it is more preferable to adjust (D90-D10)/2 to 6 μm or less. In the case where the pulverizability is good, the occurrence of fine powder is small, and the occurrence of coarse powder is small, so D90 becomes a relatively small value, and D10 becomes a relatively large value. In particular, when the pulverization property is deteriorated, it is easy to change the state in which the long base (the tail appears) to the region where the particle diameter is small. If this is the case, D10 becomes relatively small, and the result (D90-D10) /2 becomes bigger. That is, (D90-D10)/2 can be said to be an index indicating that the granularity is small.

於本發明中，藉由以上述方式抑制粉碎時之微粉的發生，可減少每體積之粉末的表面積，因此可抑制粒子表面之殘留碳酸鋰量。In the present invention, by suppressing the occurrence of fine powder during pulverization in the above manner, the surface area per volume of the powder can be reduced, so that the amount of residual lithium carbonate on the surface of the particles can be suppressed.

[實施例][Examples]

以下，提供用以更好地理解本發明及其優點之實施例，但本發明並不限定於此等實施例。The following examples are provided to better understand the present invention and its advantages, but the invention is not limited to the embodiments.

(實施例1~14)(Examples 1 to 14)

首先，使表1中記載之投入量的碳酸鋰懸浮於純水3.2公升後，投入4.8公升金屬鹽溶液。此處，金屬鹽溶液係調整各金屬之硝酸鹽的水合物，使各金屬成為表1中記載之 組成比，又，調整成使全部金屬莫耳數為14莫耳。攪拌係藉由具備攪拌翼的攪拌機以旋轉數250rpm來進行。First, the amount of lithium carbonate described in Table 1 was suspended in 3.2 liters of pure water, and then 4.8 liters of the metal salt solution was charged. Here, the metal salt solution adjusts the hydrate of the nitrate of each metal, and each metal is described in Table 1. The composition ratio was adjusted so that the total metal mole number was 14 moles. The stirring was carried out by a stirrer equipped with a stirring blade at a number of revolutions of 250 rpm.

再者，碳酸鋰之懸浮量為以Li_x N_1-y M_y O_2+α 表示製品(鋰離子二次電池正極材料，即正極活性物質)且x為表1之值的量，分別由下式算出者。Further, the amount of lithium carbonate suspended is represented by Li _x N _1-y M _y O _2+α (a positive electrode material of a lithium ion secondary battery, that is, a positive electrode active material), and x is an amount of Table 1, respectively The following formula is calculated.

W(g)=73.9×14×(1+0.5X)×AW(g)=73.9×14×(1+0.5X)×A

上述式中，「A」係用以除了作為析出反應必需之量外，預先自懸浮量減去過濾後原料中殘留之碳酸鋰以外的鋰化合物之鋰量而乘的數值。「A」，如硝酸鹽或乙酸鹽於鋰鹽作為燒成原料進行反應之情形時為0.9，如硫酸鹽或氯化物於鋰鹽未作為燒成原料進行反應之情形時為1.0。In the above formula, "A" is a value obtained by multiplying the amount of lithium of the lithium compound other than the lithium carbonate remaining in the filtered raw material from the amount of suspension in addition to the amount necessary for the precipitation reaction. "A" is 0.9 when the nitrate or acetate is reacted as a raw material of the lithium salt, and is 1.0 when the sulfate or chloride is not reacted as a raw material for the calcination.

藉由該處理，於溶液中會析出微小粒之含鋰碳酸鹽，使用壓濾機將該析出物過濾分離。By this treatment, lithium carbonate containing fine particles was precipitated in the solution, and the precipitate was separated by filtration using a filter press.

繼而，將析出物加以乾燥而獲得含鋰碳酸鹽(鋰離子電池正極材料用前驅物)。Then, the precipitate was dried to obtain a lithium-containing carbonate (precursor for a positive electrode material for a lithium ion battery).

其次，準備燒成容器，將含鋰碳酸鹽填充於該燒成容器內。其次，將燒成容器於大氣壓下放入氧氣環境爐，以表1中記載之燒成溫度加熱保持10小時後，進行冷卻，而獲得氧化物。Next, a baking container is prepared, and a lithium-containing carbonate is filled in the baking container. Next, the baking container was placed in an oxygen atmosphere furnace under atmospheric pressure, and heated and held at the baking temperature shown in Table 1 for 10 hours, and then cooled to obtain an oxide.

其次，使用小型粉碎機(hosokawamicron ACM-2EC)將所獲得之氧化物粉碎成特定粒徑之微粉為特定的粒度分布之分布幅度，而獲得鋰離子二次電池正極材料之粉末。Next, a small pulverizer (hosokawamicron ACM-2EC) was used to pulverize the obtained oxide into a specific particle size distribution powder to obtain a distribution of a specific particle size distribution, thereby obtaining a powder of a lithium ion secondary battery positive electrode material.

(實施例15)(Example 15)

實施例15，係使原料之各金屬為表1所示組成，使金 屬鹽為氯化物，析出含鋰碳酸鹽後，利用飽和碳酸鋰溶液進行清洗、過濾，除此之外，皆進行與實施例1~14相同之處理。In Example 15, the metals of the raw materials were the compositions shown in Table 1, and the gold was The salt was a chloride, and the same treatment as in Examples 1 to 14 was carried out except that the lithium carbonate was precipitated and washed with a saturated lithium carbonate solution and filtered.

(實施例16)(Embodiment 16)

實施例16，係使原料之各金屬為表1所示組成，使金屬鹽為硫酸鹽，使含鋰碳酸鹽析出後，利用飽和碳酸鋰溶液進行清洗、過濾，除此之外，皆進行與實施例1~14相同之處理。In Example 16, the metal of the raw material was a composition shown in Table 1, and the metal salt was a sulfate. After the lithium carbonate was precipitated, it was washed and filtered with a saturated lithium carbonate solution, and the same was carried out. The same treatments as in Examples 1 to 14 were carried out.

(實施例17)(Example 17)

實施例17，係使原料之各金屬為表1所示組成，並非於大氣壓下而是於120KPa之加壓下進行燒成，除此之外，皆進行與實施例1~14相同之處理。In Example 17, the same treatment as in Examples 1 to 14 was carried out except that the respective metals of the raw materials were the compositions shown in Table 1 and were not calcined under atmospheric pressure but under a pressure of 120 KPa.

(比較例1~3)(Comparative examples 1 to 3)

比較例1~3，係使原料之各金屬為表1所示組成，且碳酸鋰與金屬鹽溶液反應時的攪拌條件設為攪拌翼的旋轉數為150rpm，且對於最後之氧化物的粉碎不進行如實施例1~14般之調整，除此之外，皆進行與實施例1~14相同之處理。In Comparative Examples 1 to 3, the respective metals of the raw materials were the compositions shown in Table 1, and the stirring conditions in the reaction between the lithium carbonate and the metal salt solution were such that the number of rotations of the stirring blades was 150 rpm, and the pulverization of the last oxide was not The same procedures as in Examples 1 to 14 were carried out except that adjustments were made as in Examples 1 to 14.

(比較例4~5)(Comparative examples 4 to 5)

比較例4~5，係使原料之各金屬為表1所示組成，且並非於氧氣環境爐，而是於空氣環境爐進行燒成步驟，除此之外，皆進行與比較例1相同之處理。In Comparative Examples 4 to 5, the metals of the raw materials were the compositions shown in Table 1, and the firing steps were carried out in an air atmosphere furnace instead of the oxygen atmosphere furnace, except that the same procedure as in Comparative Example 1 was carried out. deal with.

(評價)(Evaluation) -正極材料組成之評價-- Evaluation of the composition of the positive electrode material -

各正極材料中之金屬含量係利用感應耦合電漿發射光譜分析儀(ICP-OES)測量，而算出各金屬之組成比(莫耳比)。又，含氧量係利用LECO法測量並算出α。確認該等結果如表1記載所示。The metal content in each of the positive electrode materials was measured by an inductively coupled plasma emission spectrometer (ICP-OES) to calculate the composition ratio (mol ratio) of each metal. Further, the oxygen content was measured by the LECO method and α was calculated. The results are confirmed as shown in Table 1.

-一次粒子之粒徑之評價-- Evaluation of the particle size of primary particles -

採集各正極材料之粉末，藉由雷射繞射型粒度分布測定裝置(Microtrack MT3300EX II)來測定一次粒子之粒徑。The powder of each positive electrode material was collected, and the particle diameter of the primary particles was measured by a laser diffraction type particle size distribution measuring apparatus (Microtrack MT3300EX II).

-碳量之評價-- Evaluation of carbon content -

正極材料中的碳量係依據JIS G1211、JIS G1215的規定，藉由LECO法來進行測定。即，採集0.1~0.3g的各正極材料粉末，且加入2g的不含碳之助燃材料，並放入陶瓷製的坩堝後，藉由高頻熔解爐使其燃燒。利用紅外線檢測器檢測燃燒時的成分並加以定量，藉此求得碳量。The amount of carbon in the positive electrode material was measured by the LECO method in accordance with JIS G1211 and JIS G1215. That is, 0.1 to 0.3 g of each positive electrode material powder was collected, and 2 g of a carbon-free combustion-supporting material was added, and placed in a ceramic crucible, and then burned by a high-frequency melting furnace. The amount of carbon is determined by detecting and quantifying the components at the time of combustion using an infrared detector.

-殘留碳酸鋰量之評價-- Evaluation of the amount of residual lithium carbonate -

使用鹽酸作為滴定液，藉由中和滴定來測定正極材料之粒子表面的殘留碳酸鋰量。The amount of residual lithium carbonate on the surface of the particles of the positive electrode material was measured by neutralization titration using hydrochloric acid as a titration solution.

-電池特性之評價-- Evaluation of battery characteristics -

以85：8：7之比例秤量各正極材料、導電材料與黏合劑，將黏合劑溶解於有機溶劑(N-甲基吡咯啶酮(N-methylpyrrolidone))後，再將正極材料與導電材料混合於其中進行漿料化，塗佈於Al箔上加以乾燥後進行壓製而製成正極。繼而，製作相對電極為Li之評價用2032型硬幣電池(coin cell)，使用1M-LiPF₆ 溶解於EC-DMC(1：1)而成者作為電解液，測量電流密度0.2C時之放電容量。又， 算出電流密度2C時相對於電流密度0.2C時之電池容量的放電容量之比，獲得比率特性。並且，容量保持率，係藉由在室溫下將1C之放電電流所獲得之初始放電容量與100循環後之放電容量加以比較而測得。The positive electrode material, the conductive material and the binder are weighed in a ratio of 85:8:7, and the binder is dissolved in an organic solvent (N-methylpyrrolidone), and then the positive electrode material is mixed with the conductive material. The slurry was applied thereto, coated on an Al foil, dried, and pressed to prepare a positive electrode. Then, a 2032 coin cell for evaluation of Li as a counter electrode was prepared, and 1 M-LiPF _{6 was} dissolved in EC-DMC (1:1) as an electrolyte solution, and a discharge capacity at a current density of 0.2 C was measured. . Moreover, the ratio of the discharge capacity of the battery capacity with respect to the current density of 0.2 C at the current density 2C was calculated, and the ratio characteristic was obtained. Further, the capacity retention ratio was measured by comparing the initial discharge capacity obtained by discharging a current of 1 C at room temperature with the discharge capacity after 100 cycles.

該等之結果示於表1及表2。The results of these are shown in Tables 1 and 2.

(評價)(Evaluation)

實施例1~17其電池特性皆為良好。又，原料之金屬鹽設為硝酸鹽的實施例1~14、17其電池特性特別良好。並且，並非於大氣壓力下進行燒成，而是於加壓下進行燒成的實施例17其電池特性為最好。The battery characteristics of Examples 1 to 17 were all good. Further, Examples 1 to 14 and 17 in which the metal salt of the raw material was a nitrate were particularly excellent in battery characteristics. Further, in Example 17, which was not fired under atmospheric pressure but was fired under pressure, the battery characteristics were the best.

雖然比較例1~3其作為原料的金屬之組成與本發明相同都過度地含有氧，但因為攪拌條件及粉碎條件之原因而使得電池特性不良。比較例4~5其作為原料的金屬之組成在本發明之範圍以外，並且因為攪拌條件及粉碎條件之原 因而使得電池特性不良。In Comparative Examples 1 to 3, the composition of the metal as the raw material excessively contained oxygen as in the present invention, but the battery characteristics were poor due to the stirring conditions and the pulverization conditions. The compositions of the metals of Comparative Examples 4 to 5 as raw materials are outside the scope of the present invention, and because of the conditions of stirring conditions and pulverization conditions Therefore, the battery characteristics are poor.

圖1，係正極活性物質之一次粒子及二次粒子的外觀照片。Fig. 1 is a photograph showing the appearance of primary particles and secondary particles of a positive electrode active material.

Claims (7)

一種鋰離子電池用正極活性物質，其係以下述組成式表示：Li_x Ni_1-y M_y O_2+α (該式中，M為選自Sc、Ti、V、Cr、Mn、Fe、Co、Cu、Zn、Ga、Ge、Bi、Sn、Mg、Ca、B及Zr中之1種以上，0.9≦x≦1.2，0<y≦0.7，α>0.1)，一次粒子之粒徑為1.6~2.3μm；利用LECO法測定之碳量為0.40質量%以下，利用中和滴定所測定之粒子表面的殘留鹼即碳酸鋰量為0.70質量%以下。A positive electrode active material for a lithium ion battery, which is represented by the following composition formula: Li _x Ni _1-y M _y O _2+α (wherein M is selected from the group consisting of Sc, Ti, V, Cr, Mn, Fe, One or more of Co, Cu, Zn, Ga, Ge, Bi, Sn, Mg, Ca, B, and Zr, 0.9≦x≦1.2, 0<y≦0.7, α>0.1), and the particle diameter of the primary particles is 1.6 to 2.3 μm; the amount of carbon measured by the LECO method is 0.40% by mass or less, and the amount of lithium carbonate, which is a residual alkali on the surface of the particles measured by the neutralization titration, is 0.70% by mass or less. 如申請專利範圍第1項之鋰離子電池用正極活性物質，其中，利用LECO法測定之碳量為0.20質量%以下，利用中和滴定所測定之粒子表面的殘留鹼即碳酸鋰量為0.60質量%以下。The positive electrode active material for a lithium ion battery according to the first aspect of the invention, wherein the amount of carbon measured by the LECO method is 0.20% by mass or less, and the amount of residual alkali on the surface of the particle measured by the neutralization titration is 0.60 mass. %the following. 如申請專利範圍第1或2項之鋰離子電池用正極活性物質，其中，該M為選自Mn及Co中之1種以上。The positive electrode active material for a lithium ion battery according to the first or second aspect of the invention, wherein the M is one or more selected from the group consisting of Mn and Co. 如申請專利範圍第1或2項之鋰離子電池用正極活性物質，其中，該組成式中，α>0.15。The positive electrode active material for a lithium ion battery according to claim 1 or 2, wherein α>0.15 in the composition formula. 如申請專利範圍第4項之鋰離子電池用正極活性物質，其中，該組成式中，α>0.20。The positive electrode active material for a lithium ion battery according to the fourth aspect of the invention, wherein in the composition formula, α>0.20. 一種鋰離子電池用正極，其使用有申請專利範圍第1或2項之鋰離子電池用正極活性物質。A positive electrode for a lithium ion battery using the positive electrode active material for a lithium ion battery according to claim 1 or 2. 一種鋰離子電池，其使用有申請專利範圍第6項之鋰 離子電池用正極。A lithium ion battery using lithium as claimed in claim 6 Positive electrode for ion batteries.