TWI547000B - Cathode of lithium-ion battery and method for making same - Google Patents
Cathode of lithium-ion battery and method for making same Download PDFInfo
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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Description
本發明涉及一種鋰離子電池正極及其製備方法，尤其涉及一種基於奈米碳管的鋰離子電池正極及其製備方法。 The invention relates to a positive electrode of a lithium ion battery and a preparation method thereof, in particular to a positive electrode of a lithium ion battery based on a carbon nanotube and a preparation method thereof.
鋰離子電池係一種新型的綠色化學電源，與傳統的鎳鎘電池、鎳氫電池相比具有電壓高、壽命長、能量密度大的優點。自1990年日本索尼公司推出第一代鋰離子電池後，它已經得到迅速發展並廣泛用於各種可擕式設備。 Lithium-ion battery is a new type of green chemical power source. Compared with traditional nickel-cadmium batteries and nickel-hydrogen batteries, it has the advantages of high voltage, long life and high energy density. Since Sony introduced the first generation of lithium-ion batteries in 1990, it has been rapidly developed and widely used in a variety of portable devices.
鋰離子電池正極包括正極材料，正極材料主要由正極活性材料構成。鋰離子電池正極的結構有兩種，一種係直接採用具有自支撐結構的正極材料作為鋰離子電池正極，一種係將正極材料塗敷或固定於一集電體上制得。正極活性材料一般選用嵌入化合物，常見的有氧化鈷鋰、氧化鎳鋰、氧化錳鋰等，其他的正極材料的活性物質還包括鐵的氧化物，其他金屬氧化物等。然，由於這些正極活性材料本身的導電性能差，電極的內阻較大，放電深度不夠，結果導致正極活性材料的利用率低，電極的殘餘容量大，故改善活性物質和集電體之間以及活性材料顆粒之間的導電性對鋰離子電池正極的性能至關重要，故，在實際應用中一般需要加入導電劑來改善活性材料的導電性能。 The positive electrode of the lithium ion battery includes a positive electrode material, and the positive electrode material is mainly composed of a positive electrode active material. There are two kinds of structures for the positive electrode of a lithium ion battery, one is directly using a positive electrode material having a self-supporting structure as a positive electrode of a lithium ion battery, and the other is obtained by coating or fixing a positive electrode material on a current collector. The positive electrode active material is generally selected from an intercalation compound, and commonly used are lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, etc. The active materials of other positive electrode materials include iron oxides and other metal oxides. However, since the positive electrode active material itself has poor conductivity, the internal resistance of the electrode is large, and the depth of discharge is insufficient. As a result, the utilization rate of the positive electrode active material is low, and the residual capacity of the electrode is large, so that the active material and the current collector are improved. And the conductivity between the active material particles is critical to the performance of the positive electrode of the lithium ion battery. Therefore, in practical applications, it is generally required to add a conductive agent to improve the electrical conductivity of the active material.
導電劑的種類及用量對活性物質的電極比容量及倍率放電行為有較大的影響。石墨、乙炔黑和碳纖維具有導電性好、密度小、結構穩定以及化學性質穩定等特性，常被用作鋰離子電池正極材料的導電劑。為了充分利用活性物質，這些導電劑在正極材料中的質量百分含量通常達到10%，使鋰離子電池正極的質量和體積增加。 The type and amount of the conductive agent have a great influence on the specific capacity of the electrode of the active material and the discharge behavior of the rate. Graphite, acetylene black and carbon fiber have good electrical conductivity, low density, stable structure and stable chemical properties, and are often used as conductive agents for lithium ion battery cathode materials. In order to make full use of the active material, the mass percentage of these conductive agents in the positive electrode material is usually 10%, which increases the mass and volume of the positive electrode of the lithium ion battery.
故，提供一種與先前技術相比在同等質量和體積前提下具有較低的內阻、較好的充放電性能或者與先前技術相比在同等內阻和充放電性能的前提下具有質量輕、體積小的鋰離子電池正極及其製備方法實為必要。 Therefore, it is provided with a lower internal resistance, better charge and discharge performance under the premise of the same quality and volume compared with the prior art, or has a light weight under the premise of equivalent internal resistance and charge and discharge performance compared with the prior art. A small-sized lithium ion battery positive electrode and a preparation method thereof are really necessary.
該鋰離子電池正極包括：正極活性材料、粘合劑，其中，該鋰離子電池正極進一步包括複數個奈米碳管，該複數個奈米碳管均勻分散在該鋰離子電池中，且該複數個奈米碳管的質量百分比大於等於0.001wt%小於1wt%。 The positive electrode of the lithium ion battery includes: a positive electrode active material, a binder, wherein the positive electrode of the lithium ion battery further comprises a plurality of carbon nanotubes, the plurality of carbon nanotubes are uniformly dispersed in the lithium ion battery, and the plurality The mass percentage of the carbon nanotubes is 0.001 wt% or more and less than 1 wt%.
一種鋰離子電池正極的製備方法，包括以下步驟：提供一膏狀混合物，該膏狀混合物包括鋰離子電池正極活性材料和粘合劑；將該膏狀混合物軋成一片狀結構；在該片狀結構的表面均勻地形成一奈米碳管層狀結構，從而形成一正極預製體；捲曲該正極預製體，將捲曲後的正極預製體軋成鋰離子電池正極片；以及烘乾該鋰離子電池正極片。 A method for preparing a positive electrode of a lithium ion battery, comprising the steps of: providing a paste mixture comprising a positive active material of a lithium ion battery and a binder; rolling the paste mixture into a sheet structure; The surface of the structure uniformly forms a carbon nanotube layer structure to form a positive electrode preform; the positive electrode preform is crimped, the curled positive electrode preform is rolled into a positive electrode of a lithium ion battery; and the lithium ion battery is dried Positive electrode sheet.
相較於先前技術，本發明所提供的鋰離子電池正極中，奈米碳管均勻分佈，奈米碳管在質量百分比大於0.001wt%小於1wt%的情況下，即可使鋰離子電池正極具有較低的內阻；同時，由於奈米碳 管的質量含量較小，在與先前技術中的鋰離子電池質量相同的情況下，可使鋰離子電池正極中活性物質的質量比提高，使鋰離子電池的充放電性能較好；另外，在鋰離子電池中的正極活性物質和導電劑的質量一定的情況下，由於奈米碳管的質量含量較小及可以明顯提高鋰離子電池正極的導電性，無需添加其他的導電顆粒，故，該鋰離子電池正極的質量和體積較小，使用該鋰離子電池正極的鋰離子電池的質量和體積亦會減小。 Compared with the prior art, in the positive electrode of the lithium ion battery provided by the invention, the carbon nanotubes are uniformly distributed, and the carbon nanotubes have a positive electrode of the lithium ion battery at a mass percentage of more than 0.001 wt% and less than 1 wt%. Lower internal resistance; at the same time, due to nanocarbon The mass content of the tube is small, and the mass ratio of the active material in the positive electrode of the lithium ion battery can be improved under the condition of the same quality as the lithium ion battery in the prior art, so that the charge and discharge performance of the lithium ion battery is better; When the mass of the positive electrode active material and the conductive agent in the lithium ion battery is constant, since the mass content of the carbon nanotube is small and the conductivity of the positive electrode of the lithium ion battery can be remarkably improved, it is not necessary to add other conductive particles, so The mass and volume of the positive electrode of the lithium ion battery are small, and the mass and volume of the lithium ion battery using the positive electrode of the lithium ion battery are also reduced.
相較於先前技術，本發明所提供的鋰離子電池正極的製備方法將奈米碳管層狀結構形成於包括正極活性材料的片狀結構表面後再滾軋，無需解決奈米碳管在正極活性材料中的分散問題，操作簡單。 Compared with the prior art, the method for preparing a positive electrode of a lithium ion battery provided by the present invention forms a layer structure of a carbon nanotube on a surface of a sheet structure including a positive electrode active material, and then rolls it, without solving the problem of the carbon nanotube in the positive electrode. The problem of dispersion in the active material is simple to operate.
圖1為本發明第一實施例所提供的鋰離子電池正極的製備方法的流程圖。 1 is a flow chart of a method for preparing a positive electrode of a lithium ion battery according to a first embodiment of the present invention.
圖2為本發明所提供的鋰離子電池正極截面的掃描電鏡照片。 2 is a scanning electron micrograph of a cross section of a positive electrode of a lithium ion battery provided by the present invention.
圖3為本發明所提供的鋰離子電池正極與只加入炭黑作為導電劑的鋰離子電池正極的充放電性能的對比圖。 3 is a comparison diagram of charge and discharge performance of a positive electrode of a lithium ion battery provided by the present invention and a positive electrode of a lithium ion battery in which only carbon black is added as a conductive agent.
以下將結合附圖及具體實施例對本發明實施例作進一步的詳細說明。 The embodiments of the present invention will be further described in detail below with reference to the drawings and specific embodiments.
請參閱圖1，本發明實施例提供一種鋰離子電池正極的製備方法。本發明實施例鋰離子電池正極的製備方法主要包括以下幾個步驟： 步驟一、提供一膏狀混合物，該膏狀混合物包括鋰離子電池正極活性材料和粘合劑。 Referring to FIG. 1 , an embodiment of the present invention provides a method for preparing a positive electrode of a lithium ion battery. The preparation method of the positive electrode of the lithium ion battery of the embodiment of the invention mainly comprises the following steps: Step 1. A paste mixture is provided, the paste mixture comprising a lithium ion battery positive active material and a binder.
所述正極活性材料可為磷酸鐵鋰(LiFePO4)、鋰鎳鈷(LiNi0.8Co0.2O2)、鋰鎳鈷錳(LiNi1/3Co1/3Mn1/3O2)、鈷酸鋰(LiCoO2)、鎳酸鋰(LiNiO2)及錳酸鋰(LiMn2O4)中的一種或幾種。本實施例中選用磷酸鐵鋰做為正極活性材料。 The positive electrode active material may be lithium iron phosphate (LiFePO 4 ), lithium nickel cobalt (LiNi 0.8 Co 0.2 O 2 ), lithium nickel cobalt manganese (LiNi 1/3 Co 1/3 Mn 1/3 O 2 ), cobalt acid One or more of lithium (LiCoO 2 ), lithium nickelate (LiNiO 2 ), and lithium manganate (LiMn 2 O 4 ). In the present embodiment, lithium iron phosphate is selected as the positive electrode active material.
所述粘合劑包括粘合材料和溶劑。粘合材料可以為含氟樹脂或聚烯烴化合物，所述聚烯烴化合物可選擇為聚偏二氟乙烯(PVDF)、聚四氟乙烯(PTFE)或丁苯橡膠(SBR)等。 The binder includes an adhesive material and a solvent. The binder material may be a fluorine-containing resin or a polyolefin compound, and the polyolefin compound may be selected from polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), or styrene-butadiene rubber (SBR).
所述膏狀混合物的製備方法包括以下步驟：首先，提供一粘合劑，該粘合劑包括粘合材料和溶劑。 The method of preparing the paste mixture comprises the steps of first providing an adhesive comprising a binding material and a solvent.
該粘合材料均勻分散於該溶劑中形成一懸濁液狀態的粘合劑或者溶液狀態的粘合劑。該溶劑可以為乙醇、乙二醇、N-甲基吡咯烷酮(NMP)及水中的一種或幾種。所述粘合劑中粘合材料的質量濃度為5%~60%。本實施例中的溶劑為水，粘合材料為聚四氟乙烯，聚四氟乙烯分散於水中，形成一懸濁液狀態的粘合劑，所述粘合劑中粘合材料的質量濃度為20%。 The binder is uniformly dispersed in the solvent to form a binder in a suspension state or a binder in a solution state. The solvent may be one or more of ethanol, ethylene glycol, N-methylpyrrolidone (NMP), and water. The binder has a mass concentration of the binder in the range of 5% to 60%. The solvent in the embodiment is water, the bonding material is polytetrafluoroethylene, and the polytetrafluoroethylene is dispersed in water to form a binder in a suspension state, and the mass concentration of the binder in the binder is 20%.
其次，將鋰離子電池正極活性材料粉末加入該粘合劑中，攪拌均勻，形成一膏狀混合物。 Next, a lithium ion battery positive active material powder is added to the binder and stirred uniformly to form a paste mixture.
該膏狀混合物中，鋰離子電池正極活性材料與粘合材料的質量比為5：1~20：1。可以理解，為使正極活性材料加入到粘合劑中能形成膏狀混合物，所加入正極活性材料的量與粘合劑的濃度相關。當粘合劑的濃度較大時，需要的正極活性材料的量較小，當粘合 劑的濃度較小時，需要的正極活性材料的量較多。本實施例中，磷酸鐵鋰與聚四氟乙烯的質量比為8：1。 In the paste mixture, the mass ratio of the positive active material of the lithium ion battery to the binding material is 5:1 to 20:1. It is understood that in order to form a paste mixture by adding a positive electrode active material to the binder, the amount of the positive electrode active material added is related to the concentration of the binder. When the concentration of the binder is large, the amount of the positive electrode active material required is small when bonding When the concentration of the agent is small, the amount of the positive electrode active material required is large. In this embodiment, the mass ratio of lithium iron phosphate to polytetrafluoroethylene is 8:1.
可選擇地，在將正極材料粉末加入粘合劑之前，還可以在正極材料粉末中加入少量炭黑粉末，混合均勻後，再將該混合的粉末加入粘合劑中，炭黑與鋰離子電池正極活性材料的質量比小於等於0.1：1，優選地為0.02：1。 Alternatively, a small amount of carbon black powder may be added to the positive electrode material powder before the positive electrode material powder is added to the binder, and after mixing uniformly, the mixed powder is added to the binder, the carbon black and the lithium ion battery. The mass ratio of the positive electrode active material is 0.1:1 or less, preferably 0.02:1.
步驟二、將該膏狀混合物軋成一片狀結構。 Step 2. The paste mixture is rolled into a sheet structure.
該片狀結構的厚度不限，優選為10微米~1毫米。該片狀結構的形狀不限，可以為方形、圓形或不規則形狀。 The thickness of the sheet structure is not limited, and is preferably 10 μm to 1 mm. The shape of the sheet structure is not limited and may be square, circular or irregular.
所述膏狀混合物可在一軋片機可以通過滾軋或垂直下壓的方式壓成片狀結構。該膏狀混合物可以直接軋成片狀結構，也可以將該膏狀混合物包裹於一柔性薄片中再進行軋片。該柔性薄片可以為鋁箔片、塑膠薄膜或者紙張。本實施例中，所述將膏狀混合物軋片的過程具體包括以下步驟：首先，將該膏狀混合物包裹於一鋁箔片；其次，將包裹有膏狀混合物的鋁箔片放入一軋片機中滾軋形成片狀結構，該軋片機包括兩個滾軋輪；最後，將鋁箔片從該片狀結構上揭下。通過將該膏狀混合物包裹於一柔性薄片中再進行軋片可以防止膏狀混合物被軋片機污染，還可以防止膏狀混合物在軋片過程中粘到軋片機上，造成材料浪費。 The paste mixture can be pressed into a sheet-like structure by means of rolling or vertical pressing on a sheet rolling machine. The paste mixture may be directly rolled into a sheet structure, or the paste mixture may be wrapped in a flexible sheet and then rolled. The flexible sheet may be an aluminum foil, a plastic film or paper. In this embodiment, the process of rolling the paste mixture comprises the following steps: first, wrapping the paste mixture on an aluminum foil sheet; secondly, placing the aluminum foil sheet wrapped with the cream mixture into a sheet rolling machine The middle rolling forms a sheet-like structure, and the rolling mill includes two rolling wheels; finally, the aluminum foil is peeled off from the sheet structure. By wrapping the paste mixture in a flexible sheet and then rolling the sheet, the paste mixture can be prevented from being contaminated by the sheet rolling machine, and the paste mixture can be prevented from sticking to the sheet rolling machine during the sheet rolling, resulting in waste of material.
步驟三、在該片狀結構的表面均勻地形成一奈米碳管層狀結構，從而形成一正極預製體。 Step 3: uniformly forming a carbon nanotube layer structure on the surface of the sheet structure to form a positive electrode preform.
奈米碳管層狀結構可以為通過將一含有奈米碳管的漿料噴塗或塗敷於該片狀結構的表面形成，也可以直接將奈米碳管層狀結構鋪 設於片狀結構的表面。優選地，所述奈米碳管層狀結構為一自支撐結構。所謂自支撐係指奈米碳管層狀結構無需基體支撐，可自支撐保持一層的形態。該自支撐的奈米碳管結構可以通過鋪設方式形成於片狀結構的表面。當採用自支撐的奈米碳管層狀結構時，無須將奈米碳管形成漿料，無需解決奈米碳管的分散問題，也不會在鋰離子電池正極中引入其他雜質。且，採用自支撐的奈米碳管層狀結構可以通過鋪設的方式將奈米碳管層狀結構形成於片狀結構表面，操作簡單。 The carbon nanotube layer structure may be formed by spraying or coating a slurry containing a carbon nanotube on the surface of the sheet structure, or directly laminating the carbon nanotube layer structure. It is provided on the surface of the sheet structure. Preferably, the carbon nanotube layered structure is a self-supporting structure. The so-called self-supporting means that the carbon nanotube layered structure can be self-supported to maintain a layer shape without the need of a matrix support. The self-supporting carbon nanotube structure can be formed on the surface of the sheet structure by laying. When the self-supporting carbon nanotube layered structure is used, it is not necessary to form a slurry of the carbon nanotubes, and it is not necessary to solve the problem of dispersion of the carbon nanotubes, and no other impurities are introduced into the positive electrode of the lithium ion battery. Moreover, the self-supporting carbon nanotube layered structure can form the carbon nanotube layered structure on the surface of the sheet structure by laying, and the operation is simple.
所述自支撐的奈米碳管層狀結構包括至少一層奈米碳管膜。當該自支撐的奈米碳管層狀結構包括兩層或兩層以上奈米碳管膜時，該複數層奈米碳管膜可層疊設置或並列設置。該奈米碳管膜包括複數個均勻分佈的奈米碳管。該奈米碳管膜可僅由奈米碳管構成，奈米碳管膜本身具有一定的粘性，故，由奈米碳管膜構成的奈米碳管層狀結構可以直接貼合於片狀結構的表面，無須粘合劑。 該奈米碳管層狀結構的厚度為10奈米~~100微米。所述奈米碳管膜可以為奈米碳管拉膜、奈米碳管絮化膜或奈米碳管碾壓膜。所述奈米碳管層狀結構可以由上述三種奈米碳管膜中的任一種或者任意兩種以上的膜層疊設置或並列設置等任意組合構成。 The self-supporting carbon nanotube layered structure comprises at least one layer of carbon nanotube film. When the self-supporting carbon nanotube layered structure comprises two or more layers of carbon nanotube film, the plurality of layers of carbon nanotube film may be stacked or juxtaposed. The carbon nanotube membrane comprises a plurality of uniformly distributed carbon nanotubes. The carbon nanotube film can be composed only of a carbon nanotube tube, and the carbon nanotube film itself has a certain viscosity, so that the carbon nanotube layer structure composed of a carbon nanotube film can directly adhere to the sheet structure. Surface, no adhesive required. The carbon nanotube layered structure has a thickness of 10 nm to 100 microns. The carbon nanotube film may be a carbon nanotube film, a carbon nanotube film or a carbon nanotube film. The carbon nanotube layered structure may be composed of any one of the above three types of carbon nanotube films or any combination of two or more types of films stacked or arranged in parallel.
(一)奈米碳管拉膜的製備方法包括以下步驟：首先，提供一奈米碳管陣列形成於一生長基底，該陣列為超順排的奈米碳管陣列。 (1) A method for preparing a carbon nanotube film comprises the steps of: firstly, providing a carbon nanotube array formed on a growth substrate, the array being a super-aligned carbon nanotube array.
該奈米碳管陣列的製備方法採用化學氣相沈積法，其具體步驟包括：(a)提供一平整生長基底，該生長基底可選用P型或N型矽生長基底，或選用形成有氧化層的矽生長基底，本發明實施例優 選為採用4英寸的矽生長基底；(b)在生長基底表面均勻形成一催化劑層，該催化劑層材料可選用鐵(Fe)、鈷(Co)、鎳(Ni)或其任意組合的合金之一；(c)將上述形成有催化劑層的生長基底在700℃~900℃的空氣中退火約30分鐘~90分鐘；(d)將處理過的生長基底置於反應爐中，在保護氣體環境下加熱到500℃~740℃，然後通入碳源氣體反應約5分鐘~30分鐘，生長得到奈米碳管陣列。該奈米碳管陣列為複數個彼此平行且垂直於生長基底生長的奈米碳管形成的純奈米碳管陣列。通過上述控制生長條件，該定向排列的奈米碳管陣列中基本不含有雜質，如無定型碳或殘留的催化劑金屬顆粒等。 The method for preparing the carbon nanotube array adopts a chemical vapor deposition method, and the specific steps thereof include: (a) providing a flat growth substrate, the growth substrate may be a P-type or N-type germanium growth substrate, or an oxide layer may be formed.矽 growth substrate, the embodiment of the invention is excellent It is selected to use a 4-inch germanium growth substrate; (b) a catalyst layer is uniformly formed on the surface of the growth substrate, and the catalyst layer material may be selected from iron (Fe), cobalt (Co), nickel (Ni) or any combination thereof. (c) annealing the growth substrate on which the catalyst layer is formed in air at 700 ° C to 900 ° C for about 30 minutes to 90 minutes; (d) placing the treated growth substrate in a reaction furnace in a protective gas atmosphere The mixture is heated to 500 ° C to 740 ° C, and then passed through a carbon source gas for about 5 minutes to 30 minutes to grow to obtain a carbon nanotube array. The carbon nanotube array is a plurality of pure carbon nanotube arrays formed of carbon nanotubes that are parallel to each other and perpendicular to the growth substrate. The aligned carbon nanotube array contains substantially no impurities, such as amorphous carbon or residual catalyst metal particles, etc., by controlling the growth conditions described above.
其次，採用一拉伸工具從奈米碳管陣列中拉取奈米碳管獲得至少一奈米碳管拉膜，其具體包括以下步驟：(a)從所述超順排奈米碳管陣列中選定一個或具有一定寬度的複數個奈米碳管，優選為採用具有一定寬度的膠帶、鑷子或夾子接觸奈米碳管陣列以選定一個或具有一定寬度的複數個奈米碳管；(b)以一定速度拉伸該選定的奈米碳管，從而形成首尾相連的複數個奈米碳管片段，進而形成一連續的奈米碳管拉膜。該拉取方向沿基本垂直於奈米碳管陣列的生長方向。 Secondly, a drawing tool is used to pull the carbon nanotubes from the carbon nanotube array to obtain at least one carbon nanotube film, which specifically comprises the following steps: (a) from the super-sequential carbon nanotube array Selecting one or a plurality of carbon nanotubes having a certain width, preferably adopting a tape, a braid or a clip having a certain width to contact the array of carbon nanotubes to select one or a plurality of carbon nanotubes having a certain width; (b The selected carbon nanotubes are drawn at a certain speed to form a plurality of carbon nanotube fragments connected end to end, thereby forming a continuous carbon nanotube film. The pull direction is substantially perpendicular to the growth direction of the nanotube array.
在上述拉伸過程中，該複數個奈米碳管片段在拉力作用下沿拉伸方向逐漸脫離生長基底的同時，由於凡德瓦爾力作用，該選定的複數個奈米碳管片段分別與其他奈米碳管片段首尾相連地連續地被拉出，從而形成一連續、均勻且具有一定寬度的奈米碳管拉膜。 In the above stretching process, the plurality of carbon nanotube segments are gradually separated from the growth substrate in the stretching direction under the tensile force, and the selected plurality of carbon nanotube segments are respectively combined with the other due to the van der Waals force. The carbon nanotube segments are continuously pulled out end to end to form a continuous, uniform, and wide-width carbon nanotube film.
該奈米碳管拉膜的寬度與奈米碳管陣列的尺寸有關，該奈米碳管 拉膜的長度不限，可根據實際需求制得。當該奈米碳管陣列的面積為4英寸時，該奈米碳管拉膜的寬度為0.5奈米~10厘米，該奈米碳管拉膜的厚度為0.5奈米~100微米。該奈米碳管拉膜的製備方法請參見範守善等人於民國96年2月12日申請的，於民國97年8月16日公開的第96105016號台灣公開專利申請“奈米碳管膜結構及其製備方法”，申請人：清華大學，鴻富錦精密工業(深圳)有限公司。為節省篇幅，僅引用於此，但上述申請所有技術揭露也應視為本發明申請技術揭露的一部分。 The width of the carbon nanotube film is related to the size of the carbon nanotube array, the carbon nanotube The length of the film is not limited and can be made according to actual needs. When the area of the carbon nanotube array is 4 inches, the width of the carbon nanotube film is 0.5 nm to 10 cm, and the thickness of the carbon nanotube film is 0.5 nm to 100 μm. For the preparation method of the carbon nanotube film, please refer to Fan Shoushan et al., filed on February 12, 1996, in the Republic of China, No. 96110016, published on August 16, 1997, Taiwan Patent Application "Nano Carbon Tube" Membrane structure and preparation method thereof, Applicant: Tsinghua University, Hongfujin Precision Industry (Shenzhen) Co., Ltd. In order to save space, only the above is cited, but all the technical disclosures of the above application are also considered as part of the technical disclosure of the present application.
(二)奈米碳管絮化膜的製備方法包括以下步驟：首先，提供一奈米碳管原料。 (2) The preparation method of the carbon nanotube flocculation membrane comprises the following steps: First, a carbon nanotube raw material is provided.
所述奈米碳管原料可以為通過化學氣相沈積法、石墨電極恒流電弧放電沈積法或鐳射蒸發沈積法等各種方法製備的奈米碳管。 The carbon nanotube raw material may be a carbon nanotube prepared by various methods such as chemical vapor deposition, graphite electrode constant current arc discharge deposition or laser evaporation deposition.
採用刀片或其他工具將上述定向排列的奈米碳管陣列從基底刮落，獲得一奈米碳管原料。優選地，所述之奈米碳管原料中，奈米碳管的長度大於100微米。 The aligned carbon nanotube arrays are scraped off the substrate using a blade or other tool to obtain a carbon nanotube material. Preferably, in the carbon nanotube raw material, the length of the carbon nanotube is greater than 100 micrometers.
其次，將上述奈米碳管原料添加到一溶劑中並進行絮化處理獲得一奈米碳管絮狀結構，將上述奈米碳管絮狀結構從溶劑中分離，並對該奈米碳管絮狀結構定型處理以獲得一奈米碳管絮化膜。 Next, the above carbon nanotube raw material is added to a solvent and subjected to flocculation treatment to obtain a nano carbon tube floc structure, and the above carbon nanotube floc structure is separated from the solvent, and the carbon nanotube is separated. The flocculated structure is shaped to obtain a carbon nanotube flocculation film.
溶劑可選用水、易揮發的有機溶劑等。絮化處理可通過採用超聲波分散處理或高強度攪拌等方法。優選地，本發明實施例採用超聲波分散10分鐘~30分鐘。由於奈米碳管具有極大的比表面積，相互纏繞的奈米碳管之間具有較大的凡德瓦爾力。上述絮化處理並不會將該奈米碳管原料中的奈米碳管完全分散在溶劑中，奈米 碳管之間通過凡德瓦爾力相互吸引、纏繞，形成網路狀結構。 The solvent can be selected from water, a volatile organic solvent, and the like. The flocculation treatment can be carried out by a method such as ultrasonic dispersion treatment or high-intensity stirring. Preferably, the embodiment of the invention uses ultrasonic dispersion for 10 minutes to 30 minutes. Due to the extremely large specific surface area of the carbon nanotubes, there is a large van der Waals force between the intertwined carbon nanotubes. The above flocculation treatment does not completely disperse the carbon nanotubes in the carbon nanotube raw material in the solvent, and the nanometer The carbon tubes are attracted and entangled by van der Waals forces to form a network structure.
所述之分離奈米碳管絮狀結構的方法具體包括以下步驟：將上述含有奈米碳管絮狀結構的溶劑倒入一放有濾紙的漏斗中；靜置乾燥一段時間從而獲得一分離的奈米碳管絮狀結構。 The method for separating the carbon nanotube floc structure specifically comprises the steps of: pouring the solvent containing the carbon nanotube floc structure into a funnel with a filter paper; and drying for a period of time to obtain a separation. Nano carbon tube floc structure.
所述之奈米碳管絮狀結構的定型處理過程具體包括以下步驟：將上述奈米碳管絮狀結構置於一容器中；將該奈米碳管絮狀結構按照預定形狀攤開；施加一定壓力於攤開的奈米碳管絮狀結構；以及，將該奈米碳管絮狀結構中殘留的溶劑烘乾或等溶劑自然揮發後獲得一奈米碳管絮化膜。 The shaping treatment process of the nano carbon tube floc structure specifically comprises the steps of: placing the above carbon nanotube floc structure in a container; spreading the nano carbon tube floc structure according to a predetermined shape; applying A certain pressure is applied to the expanded carbon nanotube floc structure; and the residual solvent in the nano carbon tube floc structure is dried or the solvent is naturally volatilized to obtain a carbon nanotube flocculation film.
可以理解，本發明可通過控制該奈米碳管絮狀結構攤開的面積來控制該奈米碳管絮化膜的厚度和麵密度。奈米碳管絮狀結構攤開的面積越大，則該奈米碳管絮化膜的厚度和麵密度就越小。 It will be appreciated that the present invention controls the thickness and areal density of the carbon nanotube flocculation membrane by controlling the area over which the carbon nanotube floc is spread. The larger the area spread by the carbon nanotube floc structure, the smaller the thickness and areal density of the carbon nanotube flocculation film.
另外，上述分離與定型處理奈米碳管絮狀結構的步驟也可直接通過抽濾的方式實現，具體包括以下步驟：提供一孔隙濾膜及一抽氣漏斗；將上述含有奈米碳管絮狀結構的溶劑經過該孔隙濾膜倒入該抽氣漏斗中；抽濾並乾燥後獲得一奈米碳管絮化膜。該孔L隙濾膜為一表面光滑、尺寸為0.22微米的濾膜。由於抽濾方式本身將提供一較大的氣壓作用於該奈米碳管絮狀結構，該奈米碳管絮狀結構經過抽濾會直接形成一均勻的奈米碳管絮化膜。且，由於孔隙濾膜表面光滑，該奈米碳管絮化膜容易剝離，得到一自支撐的奈米碳管絮化膜。 In addition, the step of separating and shaping the carbon nanotube floc structure can also be directly carried out by suction filtration, and specifically includes the following steps: providing a pore filter membrane and an air suction funnel; and the above-mentioned carbon nanotube containing The solvent of the structure is poured into the suction funnel through the pore filter membrane; after suction filtration and drying, a carbon nanotube flocculation membrane is obtained. The pore L-gap filter is a filter having a smooth surface and a size of 0.22 μm. Since the suction filtration method itself will provide a large gas pressure on the carbon nanotube floc structure, the carbon nanotube floc structure directly forms a uniform carbon nanotube flocculation membrane by suction filtration. Moreover, since the pore filter membrane surface is smooth, the carbon nanotube flocculation membrane is easily peeled off, and a self-supporting carbon nanotube flocculation membrane is obtained.
可以理解，該奈米碳管絮化膜具有一定的厚度，且通過控制該奈米碳管絮狀結構攤開的面積以及壓力大小可以控制奈米碳管絮化 膜的厚度。該奈米碳管絮化膜可作為一奈米碳管層狀結構使用，也可以將至少兩層奈米碳管絮化膜層疊設置或並排設置形成一奈米碳管層狀結構。 It can be understood that the carbon nanotube flocculation membrane has a certain thickness, and the carbon nanotube flocculation can be controlled by controlling the area of the carbon nanotube floc structure and the pressure. The thickness of the film. The carbon nanotube flocculation membrane can be used as a carbon nanotube layer structure, or at least two layers of carbon nanotube flocculation membranes can be stacked or arranged side by side to form a carbon nanotube layer structure.
(三)奈米碳管碾壓膜的製備方法包括以下步驟： 首先，提供一奈米碳管陣列形成於一生長基底，該陣列為定向排列的奈米碳管陣列。 (3) The preparation method of the carbon nanotube rolled film includes the following steps: First, an array of carbon nanotubes is provided on a growth substrate, the array being an array of aligned carbon nanotubes.
所述奈米碳管陣列優選為一超順排的奈米碳管陣列。所述奈米碳管陣列與上述奈米碳管陣列的製備方法相同。 The carbon nanotube array is preferably a super-aligned array of carbon nanotubes. The carbon nanotube array is prepared in the same manner as the above-described carbon nanotube array.
其次，採用一施壓裝置，擠壓上述奈米碳管陣列獲得一奈米碳管碾壓膜，其具體過程為：該施壓裝置施加一定的壓力於上述奈米碳管陣列上。在施壓的過程中，奈米碳管陣列在壓力的作用下會與生長基底分離，從而形成由複數個奈米碳管組成的具有自支撐結構的奈米碳管碾壓膜，且所述之複數個奈米碳管基本上與奈米碳管碾壓膜的表面平行。 Next, a carbon nanotube array is extruded by using a pressing device to obtain a carbon nanotube rolled film, wherein the pressing device applies a certain pressure to the carbon nanotube array. During the pressing process, the carbon nanotube array is separated from the growth substrate by pressure to form a carbon nanotube rolled film having a self-supporting structure composed of a plurality of carbon nanotubes, and The plurality of carbon nanotubes are substantially parallel to the surface of the carbon nanotube rolled film.
施壓裝置為一壓頭，壓頭表面光滑，壓頭的形狀及擠壓方向決定製備的奈米碳管碾壓膜中奈米碳管的排列方式。優選地，當採用平面壓頭沿垂直於上述奈米碳管陣列生長基底的方向擠壓時，可獲得奈米碳管為各向同性排列的奈米碳管碾壓膜；當採用滾軸狀壓頭沿某一固定方向碾壓時，可獲得奈米碳管沿該固定方向取向排列的奈米碳管碾壓膜；當採用滾軸狀壓頭沿不同方向碾壓時，可獲得奈米碳管沿不同方向取向排列的奈米碳管碾壓膜。 The pressing device is an indenter, the surface of the indenter is smooth, and the shape and extrusion direction of the indenter determine the arrangement of the carbon nanotubes in the prepared carbon nanotube rolled film. Preferably, when the planar indenter is pressed in a direction perpendicular to the growth substrate of the carbon nanotube array, the carbon nanotubes are obtained as isotropically arranged carbon nanotubes; when the roller is used When the indenter is rolled in a certain fixed direction, a carbon nanotube film which is aligned along the fixed direction of the carbon nanotubes can be obtained; when the roller-shaped indenter is rolled in different directions, the nanometer can be obtained. A carbon nanotube rolled film in which carbon tubes are aligned in different directions.
可以理解，當採用上述不同方式擠壓上述的奈米碳管陣列時，奈米碳管會在壓力的作用下傾倒，並與相鄰的奈米碳管通過凡德瓦 爾力相互吸引、連接形成由複數個奈米碳管組成的具有自支撐結構的奈米碳管碾壓膜。 It can be understood that when the above-mentioned carbon nanotube array is extruded in the above different manner, the carbon nanotubes are poured under the action of pressure and passed through the van der Waals with the adjacent carbon nanotubes. The force attracts and connects with each other to form a carbon nanotube film with a self-supporting structure composed of a plurality of carbon nanotubes.
可以理解，該奈米碳管碾壓膜具有一定的厚度，且通過奈米碳管陣列的高度以及壓力大小可以控制其厚度。所以該奈米碳管碾壓膜可以直接作為一奈米碳管層狀結構使用。另外，可以將至少兩層奈米碳管碾壓膜層疊設置或並排設置形成一奈米碳管層狀結構。 It can be understood that the carbon nanotube rolled film has a certain thickness, and the thickness can be controlled by the height of the carbon nanotube array and the pressure. Therefore, the carbon nanotube rolled film can be directly used as a carbon nanotube layered structure. In addition, at least two layers of carbon nanotube rolled films may be stacked or arranged side by side to form a carbon nanotube layered structure.
本實施例中，所述在片狀結構的表面均勻地形成一奈米碳管層狀結構的方法為將一自支撐的奈米碳管層狀結構直接鋪設於該片狀結構的表面，所述自支撐的奈米碳管層狀結構包括5層相互層疊設置的奈米碳管拉膜。 In this embodiment, the method for uniformly forming a carbon nanotube layer structure on the surface of the sheet structure is to directly lay a self-supporting carbon nanotube layer structure on the surface of the sheet structure. The self-supporting carbon nanotube layered structure comprises five layers of carbon nanotube film laminated on each other.
步驟四、捲曲該正極預製體，將捲曲後的正極預製體軋形成鋰離子電池正極片。 Step 4: The positive electrode preform is crimped, and the crimped positive electrode preform is rolled to form a positive electrode of a lithium ion battery.
所述捲曲的方式不限，方向不限，可以為朝一個方向捲曲也可以朝複數個方向捲曲。優選地，朝設置有奈米碳管層狀結構的正極預製體表面的方向捲曲，即捲曲後，奈米碳管層狀結構被包裹在正極預製體內。這種捲曲方式可防止奈米碳管層狀結構在滾壓過程中被破壞。該捲曲後的正極材料預製體可以直接軋成片狀結構，也可以將捲曲後的正極材料預製體包裹於一柔性薄片中再進行軋片。本實施例中，所述將捲曲後的正極材料預製體軋成鋰離子電池正極片的過程具體包括以下步驟：首先，將該捲曲後的正極材料預製體包裹於一鋁箔片；其次，將包裹有捲曲後的正極材料預製體的鋁箔片放入一軋片機中滾軋形成鋰離子電池正極片，該軋片機包括兩個滾軋輪；最後，將鋁箔片從該鋰離子電池正極片 上揭下。 The manner of crimping is not limited, and the direction is not limited, and may be curled in one direction or may be curled in a plurality of directions. Preferably, the carbon nanotube layered structure is wrapped in the positive electrode preform in the direction of the surface of the positive electrode preform provided with the carbon nanotube layer structure. This crimping method prevents the carbon nanotube layered structure from being destroyed during rolling. The crimped positive electrode material preform may be directly rolled into a sheet-like structure, or the crimped positive electrode material preform may be wrapped in a flexible sheet and then rolled. In this embodiment, the process of rolling the crimped positive electrode material preform into the positive electrode of the lithium ion battery comprises the following steps: first, wrapping the crimped positive electrode material preform on an aluminum foil; secondly, wrapping The aluminum foil having the curled positive electrode material preform is rolled into a sheet rolling machine to form a positive electrode of a lithium ion battery, the rolling mill comprising two rolling wheels; and finally, the aluminum foil is taken from the positive electrode of the lithium ion battery. Uncover it.
可選擇地，可依次多次重複步驟三和步驟四，即依次重複所述在片狀結構表面形成奈米碳管層狀結構形成正極預製體，再捲曲正極預製體，將捲曲後的正極預製體滾軋鋰離子電池正極片。經過多次形成奈米碳管層狀結構，多次滾壓之後，奈米碳管在鋰離子電池正極中的含量增加，同時，奈米碳管可更加均勻分散在鋰離子電池正極片中。每次鋪設的奈米碳管層狀結構中，奈米碳管膜的層數可以相同也可以不同。每次滾壓之後形成的鋰離子電池正極片的厚度可以相同也可以不同。 Alternatively, the third step and the fourth step may be repeated a plurality of times, that is, the formation of the carbon nanotube layer structure on the surface of the sheet structure is sequentially performed to form the positive electrode preform, and the positive electrode preform is curled, and the curled positive electrode is prefabricated. Body rolled lithium ion battery positive electrode. After a plurality of layers of carbon nanotubes are formed, the content of the carbon nanotubes in the positive electrode of the lithium ion battery increases after multiple rolling, and the carbon nanotubes can be more uniformly dispersed in the positive electrode of the lithium ion battery. In the layered structure of the carbon nanotubes laid each time, the number of layers of the carbon nanotube film may be the same or different. The thickness of the positive electrode sheets of the lithium ion battery formed after each rolling may be the same or different.
可選擇地，可多次重複步驟四，即所述捲曲正極預製體，將捲曲後的正極預製體滾軋的步驟可以重複進行。即將正極預製體經過多次捲曲和多次滾壓的步驟形成鋰離子電池正極片。這種多次捲曲和多次滾壓的方法可以使奈米碳管均勻地分散在鋰離子電池正極片中。每次滾壓之後形成的鋰離子電池正極片的厚度可以相同也可以不同。 Alternatively, the step four, that is, the crimped positive electrode preform, may be repeated a plurality of times, and the step of rolling the crimped positive electrode preform may be repeated. The positive electrode preform is subjected to a plurality of crimping and multiple rolling steps to form a positive electrode of a lithium ion battery. This multiple crimping and multiple rolling method allows the carbon nanotubes to be uniformly dispersed in the positive electrode of the lithium ion battery. The thickness of the positive electrode sheets of the lithium ion battery formed after each rolling may be the same or different.
本實施鋰中，連續4次依次重複步驟三和步驟四，每次鋪設的奈米碳管層狀結構中包括5層奈米碳管拉膜，4次鋪設奈米碳管層狀結構，共包括20層奈米碳管膜。 In the lithium implementation of this embodiment, steps 3 and 4 are repeated four times in succession, and the layered carbon nanotube layer structure includes 5 layers of carbon nanotube film and 4 layers of carbon nanotube layer structure. Includes 20 layers of carbon nanotube film.
在形成該鋰離子電池正極片之後，可進一步切割鋰離子電池正極片，形成預定的尺寸。 After the positive electrode sheet of the lithium ion battery is formed, the positive electrode sheet of the lithium ion battery can be further cut to form a predetermined size.
步驟五、烘乾該鋰離子電池正極片，形成鋰離子電池正極。 Step 5: drying the positive electrode of the lithium ion battery to form a positive electrode of the lithium ion battery.
所述烘乾該鋰離子電池正極片的過程為將該鋰離子電池正極片在100ºC~150ºC溫度下烘10~40小時。所述烘乾的步驟係將鋰離子電 池正極片中的粘合劑中的溶劑去除。 The process of drying the positive electrode sheet of the lithium ion battery is to dry the positive electrode sheet of the lithium ion battery at a temperature of 100 ° C to 150 ° C for 10 to 40 hours. The drying step is to charge lithium ions Solvent removal in the binder in the positive electrode of the cell.
所述鋰離子電池正極的大小不限，該鋰離子電池正極的厚度為10微米~~2毫米。當鋰離子電池正極為長方體結構時，其長度為100微米~300毫米，寬度為50微米~100毫米。當鋰離子電池正極為圓形結構時，其直徑為1毫米~10厘米。當該鋰離子電池正極用作微型鋰離子電池時，鋰離子電池的厚度為10微米~100微米，長度為100微米~1毫米，寬度為50微米~0.5毫米。本實施例中，該鋰離子電池正極為厚度為0.3毫米，直徑為8毫米的圓形結構。 The size of the positive electrode of the lithium ion battery is not limited, and the thickness of the positive electrode of the lithium ion battery is 10 micrometers to 2 millimeters. When the positive electrode of the lithium ion battery has a rectangular parallelepiped structure, the length is from 100 micrometers to 300 millimeters and the width is from 50 micrometers to 100 millimeters. When the positive electrode of the lithium ion battery has a circular structure, its diameter is 1 mm to 10 cm. When the lithium ion battery positive electrode is used as a micro lithium ion battery, the lithium ion battery has a thickness of 10 micrometers to 100 micrometers, a length of 100 micrometers to 1 millimeter, and a width of 50 micrometers to 0.5 millimeters. In this embodiment, the positive electrode of the lithium ion battery is a circular structure having a thickness of 0.3 mm and a diameter of 8 mm.
由上述方法製備的該鋰離子電池正極包括正極活性材料、粘合材料和複數個奈米碳管。所述奈米碳管包括單壁奈米碳管、雙壁奈米碳管或多壁奈米碳管。奈米碳管的直徑為1奈米~200奈米，所述奈米碳管的長度為10微米~1厘米。優選地，奈米碳管的長度大於300微米，當奈米碳管的長度大於300微米時，鋰離子電池正極具有更好的導電性能。請參見圖2，在鋰離子電池正極中，正極活性材料、粘合材料和奈米碳管均勻地混合在一起，其中，奈米碳管均勻地分散在鋰離子電池正極中，亦即，在鋰離子電池正極的不同區域，相等的面積或體積內奈米碳管的數量基本相等。通過控制鋪設奈米碳管層狀結構的次數和奈米碳管層狀結構的厚度，可以控制奈米碳管在鋰離子電池正極的質量百分含量。該複數個奈米碳管在該鋰離子電池正極中的質量百分比大於等於0.001wt%小於1wt%，優選地，該複數個奈米碳管在鋰離子電池正極重的質量百分比小於等於0.1wt%。所述鋰離子電池正極中，正極活性物質的質量百分比為大於等於83wt%小於等於95wt%。優選地，正極活性物質的質量百分比為大於等於89wt%小於等於 95wt%。本實施例中，鋰離子電池正極中的正極活性材料、粘合材料、奈米碳管的質量比為8：1：0.01。該複數個奈米碳管在該鋰離子電池中均勻分佈，且為各向同性，故，該鋰離子電池正極的電阻率均一。所述各向同性係指奈米碳管在鋰離子電池正極中的分佈密度係基本相同的，即單位體積的鋰離子電池中奈米碳管的質量百分含量基本相同。 The positive electrode of the lithium ion battery prepared by the above method includes a positive electrode active material, a binder material, and a plurality of carbon nanotubes. The carbon nanotubes include single-walled carbon nanotubes, double-walled carbon nanotubes or multi-walled carbon nanotubes. The diameter of the carbon nanotubes is from 1 nm to 200 nm, and the length of the carbon nanotubes is from 10 μm to 1 cm. Preferably, the length of the carbon nanotubes is greater than 300 microns, and when the length of the carbon nanotubes is greater than 300 microns, the positive electrode of the lithium ion battery has better electrical conductivity. Referring to FIG. 2, in the positive electrode of the lithium ion battery, the positive electrode active material, the binding material and the carbon nanotubes are uniformly mixed together, wherein the carbon nanotubes are uniformly dispersed in the positive electrode of the lithium ion battery, that is, In different regions of the positive electrode of a lithium ion battery, the number of carbon nanotubes in an equal area or volume is substantially equal. By controlling the number of layers of the carbon nanotube layered structure and the thickness of the layer of the carbon nanotube layer, the mass percentage of the carbon nanotubes in the positive electrode of the lithium ion battery can be controlled. The mass percentage of the plurality of carbon nanotubes in the positive electrode of the lithium ion battery is 0.001 wt% or more and less than 1 wt%, and preferably, the mass percentage of the plurality of carbon nanotubes in the positive electrode of the lithium ion battery is 0.1 wt% or less. . In the positive electrode of the lithium ion battery, the mass percentage of the positive electrode active material is 83% by weight or more and 95% by weight or less. Preferably, the mass percentage of the positive electrode active material is greater than or equal to 89% by weight or less. 95wt%. In this embodiment, the mass ratio of the positive electrode active material, the binder material, and the carbon nanotubes in the positive electrode of the lithium ion battery is 8:1:0.01. The plurality of carbon nanotubes are uniformly distributed in the lithium ion battery and are isotropic, so that the positive resistivity of the positive electrode of the lithium ion battery is uniform. The isotropic means that the distribution density of the carbon nanotubes in the positive electrode of the lithium ion battery is substantially the same, that is, the mass percentage of the carbon nanotubes per unit volume of the lithium ion battery is substantially the same.
表1為由本發明所提供的鋰離子電池製備方法通過6個不同實施例所製備的鋰離子電池正極的電阻率與對比試驗中所製備的鋰離子電池正極的電阻率的對比表格。每個實施例中，鋰離子電池正極的測試尺寸為20毫米×8毫米×0.34毫米，鋰離子電池正極活性材料均為磷酸鐵鋰，粘合材料均為聚四氟乙烯，磷酸鐵鋰與聚四氟乙烯的質量比為8：1，奈米碳管層數結構中奈米碳管膜的層數和奈米碳管層狀結構的鋪設次數不同，但每個實施例中，奈米碳管的質量在鋰離子電池正極中所占的質量百分比均小於0.1wt%。對比試驗1中的鋰離子電池正極只包括磷酸鐵鋰與聚四氟乙烯，質量比為8：1。對比試驗2中的鋰離子電池包括磷酸鐵鋰、聚四氟乙烯和炭黑，磷酸鐵鋰、聚四氟乙烯和炭黑的質量比為8：1：1。 Table 1 is a comparison table of the resistivity of the positive electrode of the lithium ion battery prepared by the six different examples and the resistivity of the positive electrode of the lithium ion battery prepared in the comparative test by the lithium ion battery preparation method provided by the present invention. In each of the embodiments, the test size of the positive electrode of the lithium ion battery is 20 mm × 8 mm × 0.34 mm, and the positive active material of the lithium ion battery is lithium iron phosphate, and the bonding materials are polytetrafluoroethylene, lithium iron phosphate and poly The mass ratio of tetrafluoroethylene is 8:1, and the number of layers of the carbon nanotube film and the number of laying of the carbon nanotube layer structure in the carbon nanotube layer structure are different, but in each embodiment, the carbon carbon The mass of the tube is less than 0.1% by weight in the positive electrode of the lithium ion battery. The positive electrode of the lithium ion battery in Comparative Experiment 1 only included lithium iron phosphate and polytetrafluoroethylene, and the mass ratio was 8:1. The lithium ion battery in Comparative Test 2 included lithium iron phosphate, polytetrafluoroethylene and carbon black, and the mass ratio of lithium iron phosphate, polytetrafluoroethylene and carbon black was 8:1:1.
表1 鋰離子電池正極的電阻率對比表
由表1可以看出，本發明實施例所提供的製備方法製備的鋰離子電池正極的電阻率比對比試驗1所提供的鋰離子電池的電阻率可降低兩個數量級，即本發明實施例所提供的製備方法製備的鋰離子電池正極導電性能有明顯提高。本發明實施例所提供的製備方法製備的鋰離子電池正極中，奈米碳管的質量百分含量小於0.1wt%，而對比試驗2中，炭黑的質量百分比為10wt%，本發明實施例所提供的製備方法製備的鋰離子電池正極的電阻率與對比試驗2中的鋰離子電池正極電阻率相差不多，甚至還可以低於對比試驗2中鋰離子電池正極的電阻率。 It can be seen from Table 1 that the resistivity of the positive electrode of the lithium ion battery prepared by the preparation method provided by the embodiment of the present invention can be reduced by two orders of magnitude compared with the resistivity of the lithium ion battery provided by the comparative test 1, that is, the embodiment of the present invention The conductivity of the positive electrode of the lithium ion battery prepared by the preparation method is obviously improved. In the positive electrode of the lithium ion battery prepared by the preparation method provided by the embodiment of the invention, the mass percentage of the carbon nanotubes is less than 0.1 wt%, and in the comparative test 2, the mass percentage of the carbon black is 10 wt%, the embodiment of the invention The resistivity of the positive electrode of the lithium ion battery prepared by the preparation method is similar to that of the positive electrode of the lithium ion battery in Comparative Experiment 2, and may even be lower than the resistivity of the positive electrode of the lithium ion battery in Comparative Test 2.
進一步地，分別測量實施例1和對比試驗2中的鋰離子電池正極的比容量，該兩個鋰離子電池正極的比容量均為160-170毫安培時/克(mAh/g)。但本發明實施例所提供的製備方法製備的鋰離子電池正極中，奈米碳管的質量比小於0.1wt%，可忽略不計，故，可以使該鋰離子電池正極中的活性物質的質量比相對於對比試驗2可提高10%，即在比容量和總容量相同的條件下，由實施例1所 提供的鋰離子電池正極構成的電池具有更小的質量和體積。 Further, the specific capacities of the positive electrodes of the lithium ion batteries in Example 1 and Comparative Test 2 were respectively measured, and the specific capacities of the positive electrodes of the two lithium ion batteries were both 160-170 mAh/g (mAh/g). However, in the positive electrode of the lithium ion battery prepared by the preparation method provided by the embodiment of the present invention, the mass ratio of the carbon nanotubes is less than 0.1 wt%, which is negligible, so that the mass ratio of the active materials in the positive electrode of the lithium ion battery can be made. Compared with Comparative Test 2, it can be increased by 10%, that is, under the condition of the same specific capacity and total capacity, by the first embodiment The battery provided by the positive electrode of the lithium ion battery has a smaller mass and volume.
從上述表1中還可以看到，鋰離子電池正極中，隨著奈米碳管膜總層數的增大電阻率變小，故，奈米碳管的含量可以在其在該鋰離子電池正極中的質量百分比為0.001wt%~1wt%範圍內根據需要進行調整。 It can also be seen from Table 1 above that in the positive electrode of the lithium ion battery, as the total number of layers of the carbon nanotube film increases, the resistivity becomes smaller, so the content of the carbon nanotube can be in the lithium ion battery. The mass percentage in the positive electrode is adjusted in the range of 0.001 wt% to 1 wt% as needed.
可以理解，採用上述方法製備的鋰離子電池正極中還可以進一步包括少量的炭黑，即，該鋰離子電池正極同時包括奈米碳管和炭黑，該炭黑在鋰離子電池正極中的質量百分比小於10%，優選地，小於等於1wt%，該奈米碳管在鋰離子電池正極中的質量百分含量大於等於0.001wt%小於1wt%。當鋰離子電池正極包括少量炭黑時，由於炭黑以顆粒的形式存在，而奈米碳管為連續的線性材料，炭黑顆粒可以更好的填充在奈米碳管和鋰離子電池正極材料之間或者鋰離子電池正極材料顆粒之間，進一步提高鋰離子電池正極的導電性，增加鋰離子電池比容量。請參見圖3，其中1號鋰離子電池正極中，鈷酸鋰、炭黑、聚四氟乙烯和奈米碳管的質量比為8：0.1：1：0.005；2號鋰離子電池正極中，鈷酸鋰、炭黑和聚四氟乙烯的質量比為8：0.1：1，2號鋰離子電池正極不包括奈米碳管，1號和2號鋰離子電池正極均為圓形結構，其測試時的直徑為8厘米。從圖3可以看出，同時含有炭黑和奈米碳管的鋰離子電池正極具有較好的充放電循環性能和較大的比容量。 It can be understood that the positive electrode of the lithium ion battery prepared by the above method may further include a small amount of carbon black, that is, the positive electrode of the lithium ion battery includes both a carbon nanotube and a carbon black, and the quality of the carbon black in the positive electrode of the lithium ion battery. The percentage is less than 10%, preferably, less than or equal to 1% by weight, and the mass percentage of the carbon nanotube in the positive electrode of the lithium ion battery is 0.001% by weight or more and less than 1% by weight. When the positive electrode of the lithium ion battery includes a small amount of carbon black, since the carbon black exists in the form of particles, and the carbon nanotube is a continuous linear material, the carbon black particles can be better filled in the carbon nanotube and the lithium ion battery cathode material. Between the particles of the positive electrode material of the lithium ion battery, the conductivity of the positive electrode of the lithium ion battery is further improved, and the specific capacity of the lithium ion battery is increased. Referring to FIG. 3, in the positive electrode of the lithium ion battery No. 1, the mass ratio of lithium cobaltate, carbon black, polytetrafluoroethylene and carbon nanotubes is 8:0.1:1:0.005; in the positive electrode of the No. 2 lithium ion battery, The mass ratio of lithium cobaltate, carbon black and polytetrafluoroethylene is 8:0.1:1. The positive electrode of lithium ion battery No. 2 does not include carbon nanotubes, and the positive electrodes of lithium ion batteries No. 1 and No. 2 are circular structures. The diameter of the test was 8 cm. As can be seen from Fig. 3, the positive electrode of the lithium ion battery containing both carbon black and carbon nanotubes has better charge and discharge cycle performance and a larger specific capacity.
本發明所提供的鋰離子電池正極中，奈米碳管均勻分佈，奈米碳管在質量百分比大於等於0.001wt%小於1wt%的情況下，即可使鋰離子電池正極具有較低的內阻；同時，由於奈米碳管的質量含量較小，在鋰離子電池質量一定的情況下，可使鋰離子電池正極中 活性物質的質量比提高，使鋰離子電池的充放電性能較好；另外，在鋰離子電池中的正極活性物質和導電劑的質量一定的情況下，由於奈米碳管的質量含量較小，該鋰離子電池正極的質量和體積較小，故，使用該鋰離子電池正極的鋰離子電池的質量和體積亦會減小。 In the positive electrode of the lithium ion battery provided by the invention, the carbon nanotubes are evenly distributed, and the carbon nanotubes have a lower internal resistance in the case of a mass percentage of 0.001 wt% or more and less than 1 wt%. At the same time, due to the small mass content of the carbon nanotubes, in the case of a certain quality of the lithium ion battery, the positive electrode of the lithium ion battery can be The mass ratio of the active material is improved, so that the charge and discharge performance of the lithium ion battery is better; in addition, in the case where the mass of the positive electrode active material and the conductive agent in the lithium ion battery is constant, since the mass content of the carbon nanotube is small, The lithium ion battery positive electrode has a small mass and volume, so the mass and volume of the lithium ion battery using the lithium ion battery positive electrode are also reduced.
本發明所提供的鋰離子電池正極的製備方法以奈米碳管層狀結構為原料，將奈米碳管層狀結構鋪設於包括正極活性材料的片狀結構表面後再滾軋，無需解決奈米碳管在正極活性材料中的分散問題，操作簡單，且製備的奈米碳管正極中奈米碳管不會發生團聚現象，奈米碳管分佈均勻，故在奈米碳管含量較小的情況下也可明顯提高鋰離子電池正極材料的導電性能，從而提高該鋰離子電池充放電性能。 The method for preparing a positive electrode of a lithium ion battery provided by the invention adopts a layered structure of a carbon nanotube tube as a raw material, and lays a layered structure of a carbon nanotube tube on a surface of a sheet-like structure including a positive electrode active material, and then rolls it, without solving the solution. The problem of dispersion of the carbon nanotubes in the positive electrode active material is simple, and the carbon nanotubes in the prepared carbon nanotube positive electrode do not agglomerate, and the carbon nanotubes are evenly distributed, so the content of the carbon nanotubes is small. In the case of the lithium ion battery, the conductivity of the cathode material can be significantly improved, thereby improving the charge and discharge performance of the lithium ion battery.
綜上所述，本發明確已符合發明專利之要件，遂依法提出專利申請。惟，以上所述者僅為本發明之較佳實施例，自不能以此限制本案之申請專利範圍。舉凡熟悉本案技藝之人士援依本發明之精神所作之等效修飾或變化，皆應涵蓋於以下申請專利範圍內。 In summary, the present invention has indeed met the requirements of the invention patent, and has filed a patent application according to law. However, the above description is only a preferred embodiment of the present invention, and it is not possible to limit the scope of the patent application of the present invention. Equivalent modifications or variations made by persons skilled in the art in light of the spirit of the invention are intended to be included within the scope of the following claims.
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