阅读说明：本技术 一种锌掺杂磷酸铁锂/碳复合材料及制备方法 (Zinc-doped lithium iron phosphate/carbon composite material and preparation method thereof ) 是由 胡培 史德友 徐杉 刘航 高川 于 2019-06-28 设计创作，主要内容包括：本发明公开了一种锌掺杂磷酸铁锂/碳复合材料及制备方法,包括以下步骤,磷酸铁、碳酸锂、葡萄糖、乙酸锌为原料,以去离子水为分散剂形成浆料,浆料搅拌处理后进行超声分散；将分散均匀的浆料置于玛瑙罐中,在行星式球磨机上湿法球磨处理,球磨后的浆料进行微波处理；微波处理后的浆液通过喷雾干燥机干燥后得到半成品粉末,半成品粉末在球磨罐干磨处理,进行一次粉碎；一次粉碎颗粒在保护气氛下进行高温煅烧处理后进行二次粉碎后制得磷酸铁锂。通过过渡金属锌元素掺杂和碳包覆共改性,可显著提高磷酸铁锂动力电池容量和电性能。(The invention discloses a zinc-doped lithium iron phosphate/carbon composite material and a preparation method thereof, wherein the preparation method comprises the following steps of taking iron phosphate, lithium carbonate, glucose and zinc acetate as raw materials, taking deionized water as a dispersing agent to form slurry, and carrying out ultrasonic dispersion after the slurry is stirred; placing the uniformly dispersed slurry in an agate tank, carrying out wet ball milling treatment on the slurry in a planetary ball mill, and carrying out microwave treatment on the ball-milled slurry; drying the slurry subjected to microwave treatment by a spray dryer to obtain semi-finished powder, and performing dry grinding treatment on the semi-finished powder in a ball milling tank for primary crushing; and carrying out high-temperature calcination treatment on the primary crushed particles in a protective atmosphere, and then carrying out secondary crushing to obtain the lithium iron phosphate. Through the co-modification of transition metal zinc element doping and carbon coating, the capacity and the electrical property of the lithium iron phosphate power battery can be obviously improved.)

1. A zinc-doped lithium iron phosphate/carbon composite material and a preparation method thereof are characterized in that the method comprises the following steps:

(1) taking iron phosphate, lithium carbonate, glucose and zinc acetate as raw materials, taking deionized water as a dispersing agent to form slurry, and carrying out ultrasonic dispersion after stirring the slurry;

(2) placing the uniformly dispersed slurry in an agate tank, carrying out wet ball milling treatment on the slurry in a planetary ball mill, and carrying out microwave treatment on the ball-milled slurry;

(3) drying the slurry subjected to microwave treatment by a spray dryer to obtain semi-finished powder, and performing dry grinding treatment on the semi-finished powder in a ball milling tank for primary crushing;

(4) and carrying out high-temperature calcination treatment on the primary crushed particles in a protective atmosphere, and then carrying out secondary crushing to obtain the lithium iron phosphate.

2. The zinc-doped lithium iron phosphate/carbon composite material and the preparation method thereof as claimed in claim 1, wherein the stirring speed in step (1) is 300-400r/min, the stirring time is 0.5-1h, the ultrasonic dispersion setting frequency is 60-80kHz, and the ultrasonic time is 1-2 h.

3. The zinc-doped lithium iron phosphate/carbon composite material and the preparation method thereof as claimed in claim 1, wherein the ball-to-material ratio of the ball milling treatment in the step (2) is 10:1, the rotation speed is 800-; the microwave treatment power is 300-500W, and the microwave treatment time is 2-3 h.

4. The zinc-doped lithium iron phosphate/carbon composite material and the preparation method thereof as claimed in claim 1, wherein the drying temperature of the spray dryer in the step (3) is 250-300 ℃, the rotation speed of the ball milling process is 800-.

5. The zinc-doped lithium iron phosphate/carbon composite material and the preparation method thereof as claimed in claim 1, wherein the protective atmosphere in step (4) is nitrogen or argon, the sintering temperature is 700-800 ℃, and the sintering time is 7-10 h.

Technical Field

The invention belongs to the technical field of new energy materials, relates to a preparation method of lithium iron phosphate serving as a lithium ion battery anode material, and particularly relates to a zinc-doped lithium iron phosphate/carbon composite material and a preparation method thereof.

Background

With the rapid development of new energy automobiles and other related industries, the market demand of power batteries is rapidly increased, and the anode materials of domestic power batteries mainly comprise lithium iron phosphate and ternary lithium iron phosphate. Along with subsidy moves back the slope, advantages such as low cost, long-life, high security of lithium iron phosphate show in passenger car, commodity circulation car field, and the market space is still wide in addition to the leading position of lithium iron phosphate in the passenger train market to and the application in the energy storage market in the later stage.

However, lithium iron phosphate has low electron conductivity and lithium ion mobility, which seriously affect electrochemical performance and restrict the application of the lithium iron phosphate in commercial lithium ion batteries. Currently, there are two main ways to improve the electronic conductivity: (1) the lithium iron phosphate is compounded with a high conductive agent to increase the electronic conductivity, and the electrochemical performance of the material is improved through carbon coating. (2) Increasing the intrinsic conductivity of lithium iron phosphate, e.g. by doping the material with metal cations, by doping Li in the crystal⁺Bit or Fe²⁺Bit replacement, crystal structure enhancement and electron conduction rate improvement.

Disclosure of Invention

In order to solve the defects of low electronic conductivity and low lithium ion mobility of lithium iron phosphate, the invention provides a zinc-doped lithium iron phosphate/carbon composite material and a preparation method thereof, zinc is transition metal with the proton number similar to that of iron, and the surface carbon-coated and zinc metal ion-doped LiFe is prepared by ultrasonic dispersion, wet ball milling, microwave treatment, high-temperature solid phase sintering and secondary particle forming_0.9M_0.1PO₄(M=Zn)。

The invention provides a zinc-doped lithium iron phosphate/carbon composite material and a preparation method thereof, wherein the preparation method comprises the following steps:

(1) taking iron phosphate, lithium carbonate, glucose and zinc acetate as raw materials, taking deionized water as a dispersing agent to form slurry, and carrying out ultrasonic dispersion after stirring the slurry;

(2) placing the uniformly dispersed slurry in an agate tank, carrying out wet ball milling treatment on the slurry in a planetary ball mill, and carrying out microwave treatment on the ball-milled slurry;

(3) drying the slurry subjected to microwave treatment by a spray dryer to obtain semi-finished powder, and performing dry grinding treatment on the semi-finished powder in a ball milling tank for primary crushing;

(4) and carrying out high-temperature calcination treatment on the primary crushed particles in a protective atmosphere, and then carrying out secondary crushing to obtain the lithium iron phosphate.

As a preferable scheme, the stirring speed in the step (1) is 300-400r/min, the stirring time is 0.5-1h, the ultrasonic dispersion setting frequency is 60-80kHz, and the ultrasonic time is 1-2 h.

As a preferable scheme, the ball-material ratio of the ball-milling treatment in the step (2) is 10:1, the rotating speed is 800-; the microwave treatment power is 300-500W, and the microwave treatment time is 2-3 h.

As a preferable scheme, in the step (3), the drying temperature of the spray dryer is 250-300 ℃, the ball milling processing rotating speed is 800-.

Preferably, the protective atmosphere in the step (4) is nitrogen or argon, the sintering temperature is 700-800 ℃, and the sintering time is 7-10 h.

The invention has the following beneficial effects:

(1) the method has the advantages that the ferric phosphate is selected as a raw material, the ferric phosphate is used as a product obtained after electrochemical lithium removal of the ferric phosphate, the product and the lithium iron phosphate belong to an orthorhombic system, an iron source and a phosphorus source can be provided simultaneously, and the prepared lithium iron phosphate product has good consistency, high compaction density, excellent cycle performance, excellent rate performance and other electrochemical performances;

(2) the proton number of the zinc element is similar to that of the iron element, so that solid solution is formed to improve the conductivity, and the zinc ion doping is performed on Fe in the crystal²⁺The position replacement causes the lithium iron phosphate crystal lattice to generate distortion, generates more ion vacancies, improves Li⁺Diffusion in materialsRate, and thus improve LiFe_0.9M_0.1PO₄High rate performance of/C (M = Zn);

(3) the microwave treatment of the slurry after ball milling can be combined with the advantages of a liquid phase method, the size and the shape of primary particles of the product are controlled, the product is in a ball-like shape, the compaction density of the product is greatly improved, and the product has good volume energy density;

(4) the carbon coating is finished by drying through a spray dryer after ultrasonic dispersion and microwave treatment, the defects of non-uniform coating and uncontrollable coating in the process of carbon coating by a high-temperature solid phase method are overcome, the size and the shape of primary particles are further controlled, the tap density is improved, and the conductive capacity of the material is improved;

(5) the secondary particle crushing treatment is beneficial to controlling the granularity of the precursor and the granularity and the appearance of a product of a sintering reaction, so that the product has excellent rate performance and low-temperature performance.

Drawings

Fig. 1 is a scanning electron microscope image of the zinc-doped lithium iron phosphate/carbon composite material prepared in example 2.

Detailed Description

The following are only preferred embodiments of the present invention, and the scope of the present invention is not limited to the above embodiments, but equivalent modifications or changes made by those skilled in the art according to the present disclosure should be included in the scope of the present invention as set forth in the appended claims.