TWI416782B - Method for making electrode material of lithium battery - Google Patents
Method for making electrode material of lithium battery Download PDFInfo
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- TWI416782B TWI416782B TW099119361A TW99119361A TWI416782B TW I416782 B TWI416782 B TW I416782B TW 099119361 A TW099119361 A TW 099119361A TW 99119361 A TW99119361 A TW 99119361A TW I416782 B TWI416782 B TW I416782B
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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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Abstract
Description
本發明涉及一種鋰電池電極材料的製備方法，尤其涉及一種釩磷酸鐵鋰電極材料的製備方法。The invention relates to a preparation method of a lithium battery electrode material, in particular to a preparation method of a vanadium iron phosphate lithium electrode material.
磷酸鐵鋰(LiFePO4 )作為鋰電池電極材料以其結構穩定、安全性好、資源豐富、高溫性能和循環性能好及理論比容量高等優點備受關注。然由於其鋰離子的嵌入脫出是在一維方向上進行的，所以離子電導性差、高倍率充放電性能和低溫性能差。Lithium iron phosphate (LiFePO 4 ) as a lithium battery electrode material has attracted much attention due to its structural stability, good safety, abundant resources, high temperature performance and cycle performance, and high theoretical specific capacity. However, since the insertion and extraction of lithium ions are performed in one dimension, the ionic conductivity is poor, the high rate charge and discharge performance, and the low temperature performance are poor.
先前技術中為改善磷酸鐵鋰電極材料鋰離子擴散性能差的缺點，主要藉由細化磷酸鐵鋰顆粒尺寸的方法來減少鋰離子的擴散路徑。溶膠凝膠法和共沈澱法為細化磷酸鐵鋰顆粒尺寸通常採用的方法，該兩種方法可使所述磷酸鐵鋰顆粒尺寸達到奈米級，然溶膠凝膠法合成磷酸鐵鋰的整個過程所需時間較長，通常需要幾天或幾週，不容易實現產業化，而採用共沈澱法較容易產業化，但形成的磷酸鐵鋰顆粒易團聚。In the prior art, in order to improve the lithium ion diffusion performance of the lithium iron phosphate electrode material, the diffusion path of lithium ions is mainly reduced by refining the size of the lithium iron phosphate particles. The sol-gel method and the co-precipitation method are generally used for refining the size of lithium iron phosphate particles, and the two methods can make the lithium iron phosphate particle size reach the nanometer level, and the sol-gel method can synthesize the whole lithium iron phosphate. The process takes a long time, usually takes several days or weeks, and it is not easy to realize industrialization. However, the coprecipitation method is easier to industrialize, but the formed lithium iron phosphate particles are easily agglomerated.
有鑒於此，提供一種細化磷酸鐵鋰電極材料的製備方法實為必要，藉由該製備方法所形成的磷酸鐵鋰顆粒不易團聚，且該製備方法容易實現產業化。In view of the above, it is necessary to provide a method for preparing a lithium iron phosphate electrode material, and the lithium iron phosphate particles formed by the preparation method are not easily agglomerated, and the preparation method is easy to industrialize.
一種鋰電池電極材料的製備方法，其包括以下步驟：提供一鐵鹽和一磷源，將所述鐵鹽和磷源溶於一溶劑中，以形成一混合液；向該混合液中添加複數微顆粒填料，使該複數微顆粒填料與該混合液均勻混合，在該均勻混合的過程中，調節該混合液的PH值為1.5~5以使混合液反應形成一磷酸鐵前驅體顆粒；提供一鋰源溶液和一還原劑，將該鋰源溶液、還原劑和上述磷酸鐵前驅體顆粒均勻混合，以形成一混合漿料；乾燥並熱處理該混合漿料。A method for preparing a lithium battery electrode material, comprising the steps of: providing an iron salt and a phosphorus source, dissolving the iron salt and the phosphorus source in a solvent to form a mixed solution; adding a plurality of the mixed liquid to the mixed liquid a microparticle filler, wherein the plurality of microparticle fillers are uniformly mixed with the mixture; during the uniform mixing, the pH of the mixture is adjusted to 1.5 to 5 to react the mixture to form iron phosphate precursor particles; A lithium source solution and a reducing agent are uniformly mixed with the lithium source solution, the reducing agent and the iron phosphate precursor particles to form a mixed slurry; the mixed slurry is dried and heat treated.
一種鋰電池電極材料的製備方法，其包括以下步驟：提供一鐵鹽和一磷源，將所述鐵鹽和磷源溶於一溶劑中，以形成一混合液；將上述混合液按照100毫升/小時~150毫升/小時的流量連續輸入到一反應器中；在向所述反應器中輸入上述混合液之前或過程中，將複數微顆粒填料添加至該反應器中，並使該混合液與該複數微顆粒填料均勻混合；調節該混合液的PH值為1.5~5，反應器的溫度為25℃~50℃，混合液在反應器中的反應時間為40分鐘至2小時，從而形成水合磷酸鐵前驅體顆粒；在一惰性氣體的氛圍下，在400℃~700℃的溫度範圍內加熱所述磷酸鐵鋰前驅體顆粒2小時~24小時，從而形成無水磷酸鐵前驅體顆粒；提供一鋰源溶液和一還原劑，將該鋰源溶液、上述無水磷酸鐵前驅體顆粒和還原劑均勻混合，以形成一混合漿料；乾燥所述混合漿料，之後在一惰性氣體的氛圍中，在500℃~850℃的溫度下加熱所述乾燥後的混合漿料8小時~40個小時。A method for preparing a lithium battery electrode material, comprising the steps of: providing an iron salt and a phosphorus source, dissolving the iron salt and a phosphorus source in a solvent to form a mixed solution; and mixing the mixture according to 100 ml a flow rate of /hour to 150 ml/hr is continuously input to a reactor; a plurality of microparticle fillers are added to the reactor before or during the input of the above mixture into the reactor, and the mixture is added And uniformly mixing with the plurality of microparticle fillers; adjusting the pH of the mixture to 1.5 to 5, the temperature of the reactor is 25 ° C to 50 ° C, and the reaction time of the mixture in the reactor is 40 minutes to 2 hours, thereby forming Hydrated iron phosphate precursor particles; heating the lithium iron phosphate precursor particles in an inert gas atmosphere at a temperature ranging from 400 ° C to 700 ° C for 2 hours to 24 hours to form anhydrous iron phosphate precursor particles; a lithium source solution and a reducing agent, uniformly mixing the lithium source solution, the above anhydrous iron phosphate precursor particles and a reducing agent to form a mixed slurry; drying the mixed slurry, followed by an inert gas Wai heated at a temperature of 500 ℃ ~ 850 ℃ after drying the mixed slurry was 8 hours to 40 hours.
相較於先前技術，本發明藉由向所述混合液中添加複數微顆粒，並使該複數微顆粒與所述混合液均勻混合的方式，使該複數微顆粒與所形成的磷酸鐵前驅體顆粒產生互相摩擦、碰撞，從而增加了混合液中鐵鹽和磷源的混合強度，更有利於形成球形或類球形的水合磷酸鐵前驅體顆粒，且抑制了水合磷酸鐵前驅體顆粒的團聚和長大的作用；同時，該製備方法的整個過程所需時間較短，有利於實現產業化生產。Compared with the prior art, the present invention makes the plurality of microparticles and the formed iron phosphate precursor by adding a plurality of microparticles to the mixed solution and uniformly mixing the plurality of microparticles with the mixed solution. The particles collide and collide with each other, thereby increasing the mixing strength of the iron salt and the phosphorus source in the mixed liquid, facilitating the formation of spherical or spheroidal hydrated iron phosphate precursor particles, and inhibiting the agglomeration of the hydrated iron phosphate precursor particles. The role of growing up; at the same time, the entire process of the preparation process takes a short time, which is conducive to industrial production.
下面將結合附圖及具體實施例對本發明提供的鋰電池電極材料的製備方法作進一步的詳細說明。The preparation method of the lithium battery electrode material provided by the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.
請參閱圖1，本發明實施例提供一種磷酸鐵鋰電極材料的製備方法，其包括以下步驟：Referring to FIG. 1 , an embodiment of the present invention provides a method for preparing a lithium iron phosphate electrode material, which includes the following steps:
S1，提供一鐵鹽和一磷源，將所述鐵鹽和磷源溶於一溶劑中，以形成一混合液；S1, providing an iron salt and a phosphorus source, dissolving the iron salt and the phosphorus source in a solvent to form a mixed solution;
S2，向該混合液中添加複數微顆粒填料，使該複數微顆粒填料與該混合液均勻混合，在該均勻混合的過程中，調節該混合液的PH值為1.5~5，以使混合液反應形成一磷酸鐵前驅體顆粒；S2, adding a plurality of microparticle fillers to the mixed solution, uniformly mixing the plurality of microparticle fillers with the mixture, and adjusting the pH of the mixture to 1.5 to 5 during the uniform mixing to make the mixture Reacting to form iron monophosphate precursor particles;
S3，提供一鋰源溶液和一還原劑，將該鋰源溶液、上述磷酸鐵前驅體顆粒和還原劑均勻混合，以形成一混合漿料；S3, providing a lithium source solution and a reducing agent, uniformly mixing the lithium source solution, the iron phosphate precursor particles and the reducing agent to form a mixed slurry;
S4，乾燥並熱處理所述混合漿料。S4, drying and heat treating the mixed slurry.
以下將對該S1~S4的各步驟進行詳細說明。The respective steps of S1 to S4 will be described in detail below.
在S1步驟中，所述鐵鹽和磷源按照鐵元素與磷元素的摩爾比為1:0.8~1:1.2的比例溶於一溶劑中。所述鐵鹽可在所述溶劑中溶解，其可為氯化鐵、硝酸鐵及硫酸鐵中的一種或者幾種的混合物，且不限於該所列舉的幾種。所述磷源可溶於所述溶劑，且可形成磷酸根離子，其可為磷酸、磷酸銨、磷酸氫銨及磷酸二氫銨中的一種或幾種的混合物。所述溶劑可為水、乙醇或丙酮等，該溶劑優選為水，且該水優選為去離子水或蒸餾水，從而避免引入其他雜質元素。所述混合液中，所述鐵鹽和磷源的濃度優選為0.1mol/L~3mol/L。本實施例所述混合液中，所述鐵鹽為硝酸鐵，所述磷源為磷酸，所述溶劑為去離子水，且該硝酸鐵和磷酸的濃度均為0.2mol/L。In the step S1, the iron salt and the phosphorus source are dissolved in a solvent in a molar ratio of iron to phosphorus of 1:0.8 to 1:1.2. The iron salt may be dissolved in the solvent, which may be one or a mixture of iron chloride, iron nitrate, and iron sulfate, and is not limited to the ones listed. The phosphorus source is soluble in the solvent and may form a phosphate ion, which may be a mixture of one or more of phosphoric acid, ammonium phosphate, ammonium hydrogen phosphate, and ammonium dihydrogen phosphate. The solvent may be water, ethanol or acetone, etc., the solvent is preferably water, and the water is preferably deionized water or distilled water to avoid introduction of other impurity elements. The concentration of the iron salt and the phosphorus source in the mixed solution is preferably from 0.1 mol/L to 3 mol/L. In the mixed solution of the present embodiment, the iron salt is ferric nitrate, the phosphorus source is phosphoric acid, the solvent is deionized water, and the concentration of the ferric nitrate and phosphoric acid is 0.2 mol/L.
在S2步驟中，所述複數微顆粒填料由不溶於上述溶劑且不與上述鐵源和磷源發生反應的硬質材料組成。具體為，該複數微顆粒填料的材料可為陶瓷、石英及玻璃中的一種或者幾種，且並不限於此。該每個微顆粒填料的直徑以大於所形成的磷酸鐵前驅體顆粒的直徑為宜，可為20微米~1毫米，該複數微顆粒填料的體積佔上述混合液的體積的15%~50%。In the step S2, the plurality of microparticle fillers are composed of a hard material which is insoluble in the above solvent and does not react with the above iron source and phosphorus source. Specifically, the material of the plurality of microparticle fillers may be one or more of ceramics, quartz, and glass, and is not limited thereto. The diameter of each of the microparticle fillers is preferably larger than the diameter of the formed iron phosphate precursor particles, and may be 20 micrometers to 1 millimeter, and the volume of the plurality of microparticle fillers accounts for 15% to 50% of the volume of the mixture. .
該S2步驟具體可採用控制結晶工藝製備所述磷酸鐵前驅體顆粒，其具體可包括以下子步驟：The S2 step may specifically be performed by using a controlled crystallization process to prepare the iron phosphate precursor particles, which may specifically include the following sub-steps:
首先，將上述混合液按照一定的流量連續輸入到一反應器中，其中所述流量可為100毫升/小時~150毫升/小時，所述反應器可空置或預先注入一定量的溶劑。本實施例中，該流量為120毫升/小時，且所述反應器中注入60%體積的溶劑，該溶劑可為去離子水、蒸餾水或乙醇等，優選為，該溶劑與上述混合液中的溶劑相同，即去離子水。First, the above mixture is continuously fed to a reactor at a flow rate of 100 ml/hr to 150 ml/hr, and the reactor may be vacant or pre-filled with a certain amount of solvent. In this embodiment, the flow rate is 120 ml/hr, and the reactor is filled with 60% by volume of a solvent, and the solvent may be deionized water, distilled water or ethanol, etc., preferably, the solvent and the above mixture are The solvent is the same, ie deionized water.
其次，在向所述反應器中輸入上述混合液之前或過程中，將所述複數微顆粒填料添加至該反應器中，並使該混合液與該複數微顆粒填料均勻混合。具體為，採用攪拌方式使所述混合液和複數微顆粒填料均勻混合，該攪拌的具體方式不限，可為機械攪拌、磁力攪拌或超聲分散等，本實施例為採用磁力攪拌的方式以50~60瓦/升的功率攪拌上述混合液。Next, the plurality of microparticle fillers are added to the reactor before or during the introduction of the above mixture into the reactor, and the mixture is uniformly mixed with the plurality of microparticle fillers. Specifically, the mixing solution and the plurality of micro-particle fillers are uniformly mixed by a stirring method, and the specific manner of the stirring is not limited, and may be mechanical stirring, magnetic stirring or ultrasonic dispersion, etc., in this embodiment, a magnetic stirring method is adopted. The above mixture was stirred at a power of ~60 watts/liter.
再其次，調節輸入所述反應器中的混合液的PH值為1.5~5，從而形成水合磷酸鐵前驅體顆粒。具體為，可在上述混合液連續注入反應器的過程中，藉由向所述反應器中連續注入鹼性溶液以調節PH值，該鹼性溶液可為氨水、氫氧化鈉溶液等。本實施例中，所述鹼性溶液為氨水，所述反應器中混合液的PH值被調至2.3。在該整個反應過程中，由於所述混合液以一定的流量被連續地注入所述反應器中，故，當輸入反應器中的混合液反應一定時間之後，反應形成的水合磷酸鐵前驅體顆粒會由於混合液的連續輸入而自然溢出反應器外。收集該溢出反應器外的水合磷酸鐵前驅體顆粒。Further, the pH of the mixed liquid fed into the reactor is adjusted to 1.5 to 5 to form hydrated iron phosphate precursor particles. Specifically, in the process of continuously injecting the mixed liquid into the reactor, the pH may be adjusted by continuously injecting an alkaline solution into the reactor, and the alkaline solution may be ammonia water, a sodium hydroxide solution or the like. In this embodiment, the alkaline solution is ammonia water, and the pH of the mixed liquid in the reactor is adjusted to 2.3. During the entire reaction, since the mixed liquid is continuously injected into the reactor at a certain flow rate, the hydrated iron phosphate precursor particles formed by the reaction after the mixed liquid input to the reactor reacts for a certain period of time It will naturally overflow outside the reactor due to the continuous input of the mixed liquid. The hydrated iron phosphate precursor particles outside the overflow reactor were collected.
在上述攪拌的過程中，所述複數微顆粒填料與所形成的水合磷酸鐵沈澱產生互相摩擦、碰撞，從而增加了混合液中鐵鹽和磷源的混合強度，更有利於形成球形或類球形的水合磷酸鐵前驅體顆粒，且抑制了水合磷酸鐵前驅體顆粒的團聚和長大的作用。可以理解，該步驟若不加入該複數微顆粒，也可獲得所述水合磷酸鐵前驅體顆粒，且也可形成最終產物磷酸鐵鋰電極材料，其加入僅為在反應過程中更有效地控制水合磷酸鐵前驅體顆粒的形貌和粒徑尺寸等，進而優化該磷酸鐵鋰電極材料電化學性能。During the agitation process, the plurality of microparticle fillers and the formed hydrated iron phosphate precipitate collide and collide with each other, thereby increasing the mixing strength of the iron salt and the phosphorus source in the mixture, and is more favorable for forming a spherical or spheroidal shape. The hydrated iron phosphate precursor particles inhibit the agglomeration and growth of the hydrated iron phosphate precursor particles. It can be understood that if the step does not add the plurality of microparticles, the hydrated iron phosphate precursor particles can be obtained, and the final product lithium iron phosphate electrode material can also be formed, and the addition is only to more effectively control the hydration during the reaction. The morphology and particle size of the iron phosphate precursor particles are optimized to optimize the electrochemical properties of the lithium iron phosphate electrode material.
進一步地，為更好地控制所形成的水合磷酸鐵前驅體顆粒的粒徑，可控制輸入該反應器中混合液的溫度為25℃~50℃，藉由控制上述混合液的流量和反應器的體積大小以控制混合液在反應器中的反應時間，即停留時間為40分鐘至2小時之間。該反應溫度和反應時間會影響最終水合磷酸鐵前驅體顆粒的粒徑尺寸，反應溫度越高，反應時間越長，將會促進晶粒的長大，從而使所形成的磷酸鐵前驅體顆粒的粒徑尺寸較大。本實施例中，所述反應溫度控制在25℃，反應時間控制在1個小時。Further, in order to better control the particle size of the formed hydrated iron phosphate precursor particles, the temperature of the mixed liquid input into the reactor may be controlled to be 25 ° C to 50 ° C by controlling the flow rate of the mixed liquid and the reactor. The volume is sized to control the reaction time of the mixture in the reactor, i.e., the residence time is between 40 minutes and 2 hours. The reaction temperature and reaction time will affect the particle size of the final hydrated iron phosphate precursor particles. The higher the reaction temperature, the longer the reaction time will promote the growth of crystal grains, thereby forming the particles of the iron phosphate precursor particles. The diameter is large. In this embodiment, the reaction temperature is controlled at 25 ° C and the reaction time is controlled at 1 hour.
進一步，該S2步驟可進一步包括過濾、洗滌並乾燥所述磷酸鐵前驅體顆粒的過程。具體為，可藉由離心機將上述水合磷酸鐵前驅體顆粒篩分出，並採用去離子水或蒸餾水洗滌該篩分出的磷酸鐵前驅體顆粒，再將洗滌後的磷酸鐵前驅體顆粒在70℃ ~100℃的溫度下乾燥2~4個小時，從而獲得水合磷酸鐵前驅體顆粒，該水合磷酸鐵前驅體顆粒的直徑為20奈米~10微米。Further, the S2 step may further comprise the step of filtering, washing and drying the iron phosphate precursor particles. Specifically, the hydrated iron phosphate precursor particles may be sieved by a centrifuge, and the sieved iron phosphate precursor particles are washed with deionized water or distilled water, and the washed iron phosphate precursor particles are further disposed. The hydrated iron phosphate precursor particles are obtained by drying at a temperature of 70 ° C to 100 ° C for 2 to 4 hours, and the diameter of the hydrated iron phosphate precursor particles is 20 nm to 10 μm.
另，由於上述微顆粒填料並沒有參與反應，故，該水合磷酸鐵前驅體顆粒中仍存在該微顆粒填料，故，可進一步將該微顆粒填料篩分出，具體為，由於該微顆粒填料的直徑為20微米~1毫米，遠大於所形成的水合磷酸鐵前驅體顆粒的粒徑，故，可採用一孔徑小於微顆粒填料中的最小微顆粒的直徑並大於所形成的水合磷酸鐵前驅體顆粒中的最大微顆粒的直徑的過濾網將所述微顆粒填料篩分出，從而形成純的水合磷酸鐵前驅體顆粒。In addition, since the microparticle filler does not participate in the reaction, the microparticle filler is still present in the hydrated iron phosphate precursor particles, so the microparticle filler can be further sieved out, specifically, due to the microparticle filler. The diameter is 20 micrometers to 1 millimeter, which is much larger than the particle size of the formed hydrated iron phosphate precursor particles. Therefore, a diameter smaller than the smallest microparticles in the microparticle filler can be used and is larger than the formed hydrated iron phosphate precursor. A filter of the diameter of the largest microparticles in the bulk particles screens the microparticulate filler to form pure hydrated iron phosphate precursor particles.
請參閱圖2和圖3，該控制結晶工藝藉由控制反應器中混合液的反應溫度、反應時間及向混合液中加入微顆粒填料等方式有效控制了水合磷酸鐵晶粒的生長過程，從而使最終形成的水合磷酸鐵前驅體顆粒直徑尺寸可達到20奈米~10微米的可控範圍，且該水合磷酸鐵前驅體顆粒的形貌均為球形或類球形，且具有不結塊、分散性好等特點。可以理解，該水合磷酸鐵前驅體顆粒的形貌、粒徑尺寸及分散性等特點與最終形成的磷酸鐵鋰電極材料的形貌、粒徑尺寸及分散性有關，該水合磷酸鐵前驅體顆粒的粒徑越小、分散性越好、形貌越接近球形或類球形，則最終形成的磷酸鐵鋰電極材料的粒徑也越小、分散性也越好、形貌也越接近球形或類球形。本實施例中，該水合磷酸鐵鋰前驅體顆粒的直徑尺寸為100~200奈米。Referring to FIG. 2 and FIG. 3, the controlled crystallization process effectively controls the growth process of the hydrated iron phosphate crystal grains by controlling the reaction temperature of the mixed solution in the reactor, the reaction time, and adding the microparticle filler to the mixed solution. The final formed hydrated iron phosphate precursor particle diameter can reach a controllable range of 20 nm to 10 μm, and the morphology of the hydrated iron phosphate precursor particle is spherical or spheroidal, and has no agglomeration and dispersion. Good character and so on. It can be understood that the morphology, particle size and dispersibility of the hydrated iron phosphate precursor particles are related to the morphology, particle size and dispersibility of the finally formed lithium iron phosphate electrode material, and the hydrated iron phosphate precursor particles The smaller the particle size, the better the dispersibility, and the closer the morphology is to a spherical or spheroidal shape, the smaller the particle size of the finally formed lithium iron phosphate electrode material, the better the dispersibility and the closer the morphology to the sphere or class. spherical. In this embodiment, the hydrated lithium iron phosphate precursor particles have a diameter of 100 to 200 nm.
另，該步驟可進一步包括熱處理該水合磷酸鐵前驅體顆粒的步驟，即在一惰性氣體的氛圍下，在400℃~700℃的溫度範圍內加熱所述水合磷酸鐵前驅體顆粒2小時~24小時，本實施例為在氮氣的氛圍下，在520℃的溫度下加熱10個小時，從而去除水合磷酸鐵鋰前驅體顆粒中的結晶水，以獲得無水磷酸鐵前驅體顆粒。In addition, the step may further include the step of heat-treating the hydrated iron phosphate precursor particles, that is, heating the hydrated iron phosphate precursor particles in a temperature range of 400 ° C to 700 ° C for 2 hours to 24 in an inert gas atmosphere. In the hour, this example was heated under a nitrogen atmosphere at a temperature of 520 ° C for 10 hours to remove crystal water in the hydrated lithium iron phosphate precursor particles to obtain anhydrous iron phosphate precursor particles.
在上述S3步驟中，所述鋰源溶液為將一鋰鹽或氫氧化鋰（LiOH）溶於一溶劑中形成。該鋰鹽為一可溶性鋰鹽，可為碳酸鋰、硫酸鋰、硝酸鋰或氯化鋰等，且並不限於該所列舉的幾種。所述溶劑可為水、乙醇或丙酮等。該溶劑優選為水，且該水優選為去離子水或蒸餾水，從而避免引入其他雜質元素。所述還原劑可為抗壞血酸、氯化亞錫、硼氫化鈉或碳熱還原劑，優選為碳熱還原劑，其為可溶於上述溶劑中的還原性有機化合物，該類有機化合物均可裂解成碳，該碳熱還原劑按照鋰元素、磷元素與碳元素的摩爾比為1:1:1~ 1.2: 1:1.3的比例均勻混合。所述碳熱還原劑可為蔗糖、葡萄糖、酚醛樹脂、聚丙烯酸、聚丙烯腈、聚乙二醇或聚乙烯醇等。本實施例中，該鋰源溶液為氫氧化鋰溶液，該還原劑為蔗糖。In the above step S3, the lithium source solution is formed by dissolving a lithium salt or lithium hydroxide (LiOH) in a solvent. The lithium salt is a soluble lithium salt, and may be lithium carbonate, lithium sulfate, lithium nitrate or lithium chloride, and is not limited to the ones listed. The solvent may be water, ethanol or acetone or the like. The solvent is preferably water, and the water is preferably deionized water or distilled water to avoid introduction of other impurity elements. The reducing agent may be ascorbic acid, stannous chloride, sodium borohydride or a carbothermal reducing agent, preferably a carbothermal reducing agent, which is a reducing organic compound soluble in the above solvent, and the organic compound may be cleaved In the formation of carbon, the carbothermal reducing agent is uniformly mixed in a molar ratio of lithium element, phosphorus element and carbon element of 1:1:1 to 1.2:1:1. The carbothermal reducing agent may be sucrose, glucose, phenolic resin, polyacrylic acid, polyacrylonitrile, polyethylene glycol or polyvinyl alcohol. In this embodiment, the lithium source solution is a lithium hydroxide solution, and the reducing agent is sucrose.
為使上述鋰源溶液、還原劑和磷酸鐵前驅體顆粒均勻混合，可進一步攪拌該混合漿料一定時間，具體為藉由球磨、機械攪拌、磁力攪拌或超聲分散等方法攪拌該混合漿料。本實施例為藉由球磨方式球磨該混合漿料2小時。In order to uniformly mix the lithium source solution, the reducing agent and the iron phosphate precursor particles, the mixed slurry may be further stirred for a certain period of time, specifically, the mixed slurry is stirred by ball milling, mechanical stirring, magnetic stirring or ultrasonic dispersion. In this embodiment, the mixed slurry was ball milled by ball milling for 2 hours.
在上述S4步驟中，乾燥上述混合漿料以使其中的水分完全蒸發掉，之後直接進行所述熱處理過程。該熱處理的條件具體為：在一惰性氣體的氛圍中，在500℃~850℃的溫度下加熱所述乾燥後的混合漿料8小時~40個小時，從而使該乾燥後的混合漿料在還原劑的作用下發生還原反應，以形成磷酸鐵鋰電極材料。本實施例為在700℃的氮氣保護氛圍下加熱16個小時。請參閱圖4，在該高溫加熱的過程中，所述碳熱還原劑，即蔗糖便發生裂解產生碳，所述磷酸鐵前驅體顆粒中的鐵離子（Fe3+ ）被該碳還原形成亞鐵離子（Fe2+ ），並與鋰源發生反應，形成磷酸鐵鋰，該高溫熱處理過程中生成的碳也可起到抑制晶粒長大和團聚的作用，從而使最終形成的磷酸鐵鋰顆粒粒徑較小且分散性較好，且若該碳有殘餘，該殘餘的碳可包覆在磷酸鐵鋰顆粒的表面，從而可進一步提高磷酸鐵鋰電極材料的電子導電性。同時，由於所述磷酸鐵前驅體顆粒具有粒徑小、球形或類球形等特點，故藉由該磷酸鐵前驅體顆粒反應生成的磷酸鐵鋰顆粒也具有粒徑小、球形或類球形的特點。In the above step S4, the above mixed slurry is dried to completely evaporate the moisture therein, and then the heat treatment process is directly performed. The heat treatment is specifically carried out by heating the dried mixed slurry at a temperature of 500 ° C to 850 ° C for 8 hours to 40 hours in an inert gas atmosphere, thereby allowing the dried mixed slurry to be A reduction reaction occurs under the action of a reducing agent to form a lithium iron phosphate electrode material. This example was heated for 16 hours under a nitrogen atmosphere at 700 °C. Referring to FIG. 4, during the high-temperature heating, the carbothermal reducing agent, ie, sucrose, is cracked to generate carbon, and iron ions (Fe 3+ ) in the iron phosphate precursor particles are reduced by the carbon to form a sub Iron ions (Fe 2+ ) react with lithium source to form lithium iron phosphate. The carbon formed during the high-temperature heat treatment can also inhibit grain growth and agglomeration, so that the finally formed lithium iron phosphate particles The particle size is small and the dispersibility is good, and if the carbon has a residue, the residual carbon can be coated on the surface of the lithium iron phosphate particles, so that the electronic conductivity of the lithium iron phosphate electrode material can be further improved. At the same time, since the iron phosphate precursor particles have the characteristics of small particle size, spherical shape or spheroidal shape, the lithium iron phosphate particles formed by the reaction of the iron phosphate precursor particles also have the characteristics of small particle size, spherical shape or spheroidal shape. .
由於藉由上述氧化還原法製備的磷酸鐵鋰顆粒具有粒徑小、分散性好、球形或類球形的特點，從而有利於其作為鋰電池電極材料時，堆積密度的提高，且縮短了鋰離子在固相顆粒中的擴散路程。且該整個製備過程所需時間較短，有利於實現產業化生產。請參閱圖5為顆粒直徑為100nm~200nm左右的磷酸鐵鋰電極材料在2.5伏~4.2伏的電壓範圍內，在1C倍率下的循環性能曲線。從圖中可以看出，磷酸鐵鋰電極材料在1C倍率下的首次放電比容量為106.4mAh/g，50次循環後可逆比容量下降為95mAh/g，容量保持率高達90%，表明磷酸鐵鋰電材料的顆粒細化後可保持優異的循環性能。Since the lithium iron phosphate particles prepared by the above redox method have the characteristics of small particle size, good dispersibility, spherical or spheroidal shape, which is advantageous for the lithium-ion battery electrode material, the bulk density is improved, and the lithium ion is shortened. The diffusion path in the solid phase particles. Moreover, the entire preparation process takes a short time, which is advantageous for industrial production. Please refer to FIG. 5 for the cycle performance curve of the lithium iron phosphate electrode material with a particle diameter of about 100 nm to 200 nm in a voltage range of 2.5 volts to 4.2 volts at a rate of 1 C. It can be seen from the figure that the first discharge specific capacity of the lithium iron phosphate electrode material is 106.4 mAh/g at 1 C rate, the reversible specific capacity decreases to 95 mAh/g after 50 cycles, and the capacity retention rate is as high as 90%, indicating that iron phosphate The fineness of the particles of the lithium battery material maintains excellent cycle performance.
本發明第二實施例提供一種釩摻雜的磷酸鐵鋰電極材料的製備方法，其包括以下步驟：A second embodiment of the present invention provides a method for preparing a vanadium-doped lithium iron phosphate electrode material, which comprises the following steps:
S1，提供釩源、鐵鹽和磷源，將所述釩源、鐵鹽和磷源溶於一溶劑中，以形成一混合液；S1, providing a vanadium source, an iron salt and a phosphorus source, dissolving the vanadium source, the iron salt and the phosphorus source in a solvent to form a mixed liquid;
S2，向該混合液中添加複數微顆粒填料，使該複數微顆粒填料與該混合液均勻混合，在該均勻混合的過程中，調節該混合液的PH值為1.5~5以使混合液反應形成一釩摻雜的磷酸鐵前驅體顆粒；S2, adding a plurality of microparticle fillers to the mixed solution, uniformly mixing the plurality of microparticle fillers with the mixed solution, and adjusting the pH of the mixed solution to 1.5 to 5 during the uniform mixing to react the mixed solution Forming a vanadium-doped iron phosphate precursor particle;
S3，提供一鋰源溶液和一還原劑，將該鋰源溶液、上述釩摻雜的磷酸鐵前驅體顆粒和還原劑均勻混合，以形成一混合漿料；S3, providing a lithium source solution and a reducing agent, uniformly mixing the lithium source solution, the vanadium-doped iron phosphate precursor particles and a reducing agent to form a mixed slurry;
S4，乾燥並熱處理上述混合漿料，從而形成釩摻雜的磷酸鐵鋰電極材料。S4, drying and heat-treating the above mixed slurry to form a vanadium-doped lithium iron phosphate electrode material.
上述步驟中，僅S1步驟與上述第一實施例的S1步驟不同，其他S2~S4步驟與上述第一實施例中的S2~S4步驟基本相同，在此不再贅述。In the above steps, only the S1 step is different from the S1 step in the first embodiment, and the other S2 to S4 steps are substantially the same as the S2 to S4 steps in the first embodiment, and are not described herein again.
在S1步驟中，所述釩源、鐵鹽和磷源按照釩元素與鐵元素的摩爾數之和與磷元素的摩爾數之比為1:0.8~1:1.2的比例溶於所述溶劑中。所述釩源可為偏釩酸銨、五氧化二釩、二氧化釩或四氯化釩等，所述鐵鹽可為氯化鐵、硝酸鐵及硫酸鐵中的一種或者幾種的混合物。所述溶劑可為水、乙醇或丙酮等，該溶劑優選為水，且該水優選為去離子水或蒸餾水，從而避免引入其他雜質元素。本實施例所述混合液中，所述釩源為偏釩酸銨，所述鐵鹽為硝酸鐵，所述磷源為磷酸，所述溶劑為去離子水。該偏釩酸銨按照釩元素的摩爾分數X(V)為獲得的釩摻雜的磷酸鐵前驅體顆粒的1%~5%提供，本實施例X(V)分別按照1%、3%和5%提供該偏釩酸銨。In the step S1, the vanadium source, the iron salt and the phosphorus source are dissolved in the solvent in a ratio of a molar ratio of a vanadium element to an iron element to a molar ratio of a phosphorus element of 1:0.8 to 1:1.2. . The vanadium source may be ammonium metavanadate, vanadium pentoxide, vanadium dioxide or vanadium tetrachloride, etc., and the iron salt may be one or a mixture of ferric chloride, iron nitrate and iron sulfate. The solvent may be water, ethanol or acetone, etc., the solvent is preferably water, and the water is preferably deionized water or distilled water to avoid introduction of other impurity elements. In the mixed solution of this embodiment, the vanadium source is ammonium metavanadate, the iron salt is ferric nitrate, the phosphorus source is phosphoric acid, and the solvent is deionized water. The ammonium metavanadate is provided in an amount of 1% to 5% of the vanadium-doped iron phosphate precursor particles obtained according to the molar fraction X (V) of the vanadium element, and X(V) of the present embodiment is 1%, 3% and The ammonium metavanadate is provided in 5%.
請參閱圖6，本實施例測量出了未經摻釩的磷酸鐵鋰材料與摻雜釩1%、3%和5%的磷酸鐵鋰材料的XRD譜圖，該譜圖顯示釩摻雜的磷酸鐵鋰材料與純相的磷酸鐵鋰譜圖一致，沒有雜峰出現，表明經過摻釩的磷酸鐵鋰材料中的釩被完全摻雜到鐵位，沒有額外的其他材料形成。Referring to FIG. 6, the XRD spectrum of the undoped vanadium iron phosphate material and the doped vanadium 1%, 3% and 5% lithium iron phosphate materials is measured, and the spectrum shows vanadium doping. The lithium iron phosphate material is consistent with the pure phase lithium iron phosphate spectrum, and no hetero peaks appear, indicating that the vanadium in the vanadium-doped lithium iron phosphate material is completely doped to the iron level, and no additional materials are formed.
請參閱圖7，從該圖中可以發現，釩摻雜的水合磷酸鐵前驅體顆粒較不摻釩的水合磷酸鐵前驅體顆粒粒徑更小、分散性較好，這主要是因為釩的摻雜可抑制晶粒的長大，且可阻止釩摻雜的水合磷酸鐵前驅體顆粒形成過程中發生團聚。同時，所獲得的釩摻雜的磷酸鐵前驅體顆粒也具有形貌為球形或類球形、粒徑較小、分散性較好的特點。另，由於所述釩源、鐵鹽和磷源為在一溶劑中均勻混合，從而可使得所述釩源、鐵鹽和磷源達到原子級的均勻混合，從而可使釩均勻地摻雜入步驟S2所形成的磷酸鐵前驅體顆粒中，從而最終形成釩均勻摻雜的磷酸鐵鋰電極材料。Referring to Figure 7, it can be seen from the figure that the vanadium-doped hydrated iron phosphate precursor particles have smaller particle size and better dispersion than the vanadium-doped hydrated iron phosphate precursor particles, mainly because of vanadium doping. The impurities inhibit the growth of the grains and prevent agglomeration during the formation of the vanadium-doped hydrated iron phosphate precursor particles. At the same time, the obtained vanadium-doped iron phosphate precursor particles also have the characteristics of spherical or spheroidal shape, small particle size and good dispersibility. In addition, since the vanadium source, the iron salt and the phosphorus source are uniformly mixed in a solvent, the vanadium source, the iron salt and the phosphorus source can be uniformly mixed at an atomic level, so that the vanadium can be uniformly doped. In the iron phosphate precursor particles formed in step S2, a vanadium iron phosphate electrode material uniformly doped with vanadium is finally formed.
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。舉凡習知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 those skilled in the art in light of the spirit of the invention are intended to be included within the scope of the following claims.
無no
圖1為本發明第一實施例提供的磷酸鐵鋰電極材料的製備方法流程圖。1 is a flow chart of a method for preparing a lithium iron phosphate electrode material according to a first embodiment of the present invention.
圖2為本發明第一實施例製備的磷酸鐵前驅體顆粒的掃描電鏡照片。2 is a scanning electron micrograph of a ferric phosphate precursor particle prepared in accordance with a first embodiment of the present invention.
圖3為本發明第一實施例製備的磷酸鐵前驅體顆粒的透射電鏡照片。Figure 3 is a transmission electron micrograph of a ferric phosphate precursor particle prepared in accordance with a first embodiment of the present invention.
圖4為本發明第一實施例製備的磷酸鐵鋰材料的掃描電鏡照片。Figure 4 is a scanning electron micrograph of a lithium iron phosphate material prepared in accordance with a first embodiment of the present invention.
圖5為採用本發明第一實施例製備的磷酸鐵鋰材料作為正極的電池在1C倍率下的比容量-循環測試曲線圖。Fig. 5 is a graph showing a specific capacity-cycle test of a battery using a lithium iron phosphate material prepared as a positive electrode of the first embodiment of the present invention at a 1C rate.
圖6本發明第一實施例製備的未摻雜釩的磷酸鐵鋰材料與第二實施例製備的釩摻雜1%、3%和5%的磷酸鐵鋰材料的XRD比較譜圖。Figure 6 is a comparison of XRD of the undoped vanadium-doped lithium iron phosphate material prepared in the first embodiment of the present invention with the vanadium-doped 1%, 3% and 5% lithium iron phosphate materials prepared in the second embodiment.
圖7為本發明第二實施例製備的釩摻雜的磷酸鐵前驅體顆粒的掃描電鏡照片。Figure 7 is a scanning electron micrograph of a vanadium-doped iron phosphate precursor particle prepared in accordance with a second embodiment of the present invention.
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| CN101118963A (en) * | 2007-05-22 | 2008-02-06 | 龚思源 | Method for preparing anode material iron phosphate lithium of lithium ion battery |
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| CN101118963A (en) * | 2007-05-22 | 2008-02-06 | 龚思源 | Method for preparing anode material iron phosphate lithium of lithium ion battery |
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