CN111252751A - Microfluidic droplet forming structural component and method for preparing solid spherical lithium iron phosphate - Google Patents

Abstract

The invention relates to a microfluidic droplet forming structure, comprising a matrix in which a continuous fluid channel, a dispersed fluid channel and a droplet formation channel are provided, and the liquid outlet of the continuous fluid channel, the liquid outlet of the dispersed fluid channel and the droplet The inlets that form the channels meet. A method for preparing solid spherical lithium iron phosphate by coupling microfluidic technology and gel method, mixing lithium acetate, nano-iron trioxide and ammonium dihydrogen phosphate in a water-ethanol solution to obtain fluid A; combining silicone oil and fluid A It is injected into the continuous fluid channel and the dispersed fluid channel respectively, and the water phase droplets are formed at the common intersection of the continuous fluid channel, the dispersed fluid channel and the droplet formation channel by the action of the fluid A through the silicone oil. The droplets flow into the droplet forming channel; the aqueous phase droplets are heated by an ultraviolet radiation source to form gel particles; the gel particles are sintered to obtain solid spherical lithium iron phosphate. The target product size can be controlled.

Description

Microfluidic droplet forming structure and method for preparing solid spherical lithium iron phosphate

technical field

The invention relates to the field of lithium batteries, in particular to a microfluidic droplet forming structure and a method for preparing solid spherical lithium iron phosphate by coupling the microfluidic technology and the gel method.

Background technique

The patent with the publication number CN106328906A provides a method for preparing a nano-spherical lithium iron phosphate positive electrode material. In the actual preparation process of the method, the uniformity of the carbon spheres is difficult to guarantee.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention is to provide a microfluidic droplet forming structure and a method for coupling the microfluidic technology and the gel method to prepare solid spherical lithium iron phosphate, so as to overcome the above-mentioned deficiencies in the prior art.

The technical solution of the present invention to solve the above-mentioned technical problems is as follows: a microfluidic droplet forming structure, including a matrix, in which a continuous fluid channel, a dispersion fluid channel and a droplet forming channel are provided, and the liquid outlet of the continuous fluid channel, The liquid outlet port of the dispersion fluid channel and the liquid inlet port of the droplet forming channel meet.

The beneficial effects of the invention are as follows: the water-phase droplet generation operation is simple, no external force is required, the target size particles can be synthesized in one step, the droplet monodispersity is good, the size is uniform, the system is closed, the consumption of reagents is small, and the reaction conditions are stable, Easy to control.

On the basis of the above technical solutions, the present invention can also be improved as follows.

Further, the continuous fluid channel, the dispersion fluid channel and the droplet forming channel together constitute a T-shape.

Further, the diameters of the continuous fluid channel, the dispersed fluid channel and the droplet formation channel are all 10-250 μm.

Further, the diameters of the continuous fluid channel, the dispersed fluid channel and the droplet formation channel are all 60 μm.

Further, the base body is made of transparent material.

The method for preparing solid spherical lithium iron phosphate by coupling microfluidic technology and gel method, and the method for preparing solid spherical lithium iron phosphate by coupling microfluidic droplet forming structure with gel method, includes the following steps:

S100, mixing lithium acetate, nano-ferric oxide and ammonium dihydrogen phosphate in a water-ethanol solution to obtain fluid A, for subsequent use;

S200, inject the silicone oil and the fluid A into the continuous fluid channel and the dispersed fluid channel respectively, and make the fluid A pass through the action of the silicone oil to form an aqueous liquid at the common intersection of the continuous fluid channel, the dispersed fluid channel and the droplet formation channel droplets, the formed water phase droplets flow into the droplet formation channel;

S300, using an ultraviolet radiation source to heat the water-phase droplets flowing into the droplet forming channel to form gel particles;

S400, sintering the gel particles to obtain solid spherical lithium iron phosphate.

Further, the specific preparation method of fluid A in step S100 is as follows: Lithium acetate, nano-iron trioxide and ammonium dihydrogen phosphate with a molar ratio of 2:1:1 are uniformly mixed into a water-ethanol solution containing 10% acetic acid, It is configured into a solution with a solute content of 5-30%, that is, fluid A is obtained.

Further, in step S200, the silicone oil is injected into the continuous fluid channel at a rate of 10-500 μL/h, and the fluid A is injected into the dispersion fluid channel at a rate of 0.1-100 μL/h.

Further, the silicone oil was injected into the continuous fluid channel at a rate of 15 μL/h, and the fluid A was injected into the dispersion fluid channel at a rate of 100 μL/h.

Further, in step S400, the temperature of sintering the gel particles is 1000-1800°C.

The beneficial effects of the invention are that: the microfluidic droplet generation technology is coupled with the gel method to prepare the lithium iron phosphate, so that the preparation process of the lithium iron phosphate becomes simple, and the size of the target product can be controlled, and it is easy to ensure the quality of the product. The uniformity, and the shape of the obtained solid spherical lithium iron phosphate are more regular.

Description of drawings

FIG. 1 is a schematic structural diagram of the microfluidic droplet forming structure according to the present invention;

FIG. 2 is an application diagram of the microfluidic droplet forming structure according to the present invention;

Fig. 3 is the SEM image of the solid spherical lithium iron phosphate prepared by the method of the present invention.

Detailed ways

The principles and features of the present invention will be described below with reference to the accompanying drawings. The examples are only used to explain the present invention, but not to limit the scope of the present invention.

As shown in FIG. 1 and FIG. 2 , the microfluidic droplet forming structure includes a substrate 1, in which a continuous fluid channel 110, a dispersion fluid channel 120 and a droplet forming channel 130 are opened, and the liquid outlet from the continuous fluid channel 110 In the design process, the diameters of the continuous fluid channel 110, the dispersion fluid channel 120 and the droplet forming channel 130 are all 10-250 μm. , preferably 60 μm, the continuous fluid channel 110 , the dispersion fluid channel 120 and the droplet formation channel 130 together form a T-shaped, Y-shaped, flow-focusing structure or confocal structure, which is given in the corresponding drawings of this embodiment as T-shaped, the base body 1 is made of transparent material, which is convenient for process observation.

A method for preparing solid spherical lithium iron phosphate by coupling a microfluidic technology and a gel method, comprising the following steps:

S100, mixing lithium acetate, nano-ferric oxide and ammonium dihydrogen phosphate in a water-ethanol solution to obtain fluid A, for subsequent use;

S200, inject the silicone oil and the fluid A into the continuous fluid channel 110 and the dispersion fluid channel 120 respectively, and make the fluid A pass through the silicone oil at the common intersection of the continuous fluid channel 110, the dispersion fluid channel 120 and the droplet formation channel 130 A water-phase droplet is formed at the place, and the formed water-phase droplet flows into the droplet forming channel 130;

S300, using an ultraviolet radiation source to heat the water-phase droplets flowing into the droplet forming channel 130 to form gel particles;

S400, sintering the gel particles to obtain solid spherical lithium iron phosphate.

Application example

As shown in Figure 1, Figure 2, Figure 3, a method for preparing solid spherical lithium iron phosphate by coupling microfluidic technology and gel method, including the following steps:

S100. Uniformly mix lithium acetate, nano-iron trioxide and ammonium dihydrogen phosphate with a molar ratio of 2:1:1 into a water-ethanol solution containing 10% acetic acid, and configure a solution with a solute content of 5-30% , preferably 10%, that is, fluid A is obtained, which is ready for use;

S200, use a syringe pump to inject silicone oil into the continuous fluid channel 110 at a speed of 10-500 μL/h, preferably 15 μL/h, and at the same time, use a syringe pump to inject fluid A into the dispersion fluid at a speed of 0.1-100 μL/h In the channel 120, preferably 100 μL/h, and by allowing the fluid A to pass through the silicone oil to form aqueous droplets at the common intersection of the continuous fluid channel 110, the dispersion fluid channel 120 and the droplet formation channel 130, the formed The aqueous phase droplets flow into the droplet forming channel 130;

S300, using an ultraviolet radiation source to heat the water-phase droplets flowing into the droplet forming channel 130 to form gel particles;

S400 , collecting the gel particles, and sintering the gel particles at 1000-1800° C., preferably 1,600° C., to obtain solid spherical lithium iron phosphate.

The microfluidic droplet generation technology can be coupled with one or both of the conventional carbon sphere production methods such as hydrothermal method and gel method. In the hydrothermal method, the carbon source can be an organic carbon source such as petroleum pitch, coal pitch, sucrose, glucose, starch, cellulose, sodium citrate, phenolic resin and epoxy resin. In the gel method, the gelling agent can be an organic substance such as ethanol and acetic acid, which can be dehydrated or polycondensed by dehydration, to synthesize carbon sources such as lipids.

Although the embodiments of the present invention have been shown and described above, it should be understood that the above-mentioned embodiments are exemplary and should not be construed as limiting the present invention. Embodiments are subject to variations, modifications, substitutions and variations.

Claims (10)

1. The microfluidic droplet forming structure is characterized by comprising a substrate (1), wherein a continuous fluid channel (110), a dispersed fluid channel (120) and a droplet forming channel (130) are arranged in the substrate (1), and a liquid outlet of the continuous fluid channel (110), a liquid outlet of the dispersed fluid channel (120) and a liquid inlet of the droplet forming channel (130) are intersected.

2. The microfluidic drop formation structure of claim 1, wherein the continuous fluid channel (110), the dispersive fluid channel (120), and the drop formation channel (130) collectively form a T-shape.

3. The microfluidic droplet formation structure of claim 2, wherein the continuous fluid channel (110), the dispersive fluid channel (120) and the droplet formation channel (130) each have a diameter of 10-250 μm.

4. The microfluidic drop formation structure of claim 3, wherein the continuous fluid channel (110), the dispersive fluid channel (120) and the drop formation channel (130) each have a diameter of 60 μm.

5. A microfluidic drop formation structure according to any one of claims 1 to 4, wherein the substrate (1) is made of a transparent material.

6. The method for preparing solid spherical lithium iron phosphate by coupling the microfluidic technology with the gel method is characterized by comprising the step of coupling the microfluidic droplet forming structural component as claimed in any one of claims 1 to 5 with the gel method to prepare the solid spherical lithium iron phosphate, and the method comprises the following steps:

s100, mixing lithium acetate, nano ferric oxide and ammonium dihydrogen phosphate in a water-ethanol solution to obtain a fluid A for later use;

s200, respectively injecting silicon oil and fluid A into the continuous fluid channel (110) and the dispersion fluid channel (120), enabling the fluid A to form aqueous phase droplets at the joint of the continuous fluid channel (110), the dispersion fluid channel (120) and the droplet forming channel (130) under the action of the silicon oil, and enabling the formed aqueous phase droplets to flow into the droplet forming channel (130);

s300, heating the aqueous phase liquid drops flowing into the liquid drop forming channel (130) by using an ultraviolet radiation source to form gel particles;

s400, sintering the gel particles to obtain the solid spherical lithium iron phosphate.

7. The method for preparing solid spherical lithium iron phosphate by coupling the microfluidic technology with the gel method according to claim 6, wherein the specific preparation method of the fluid A in the step S100 is as follows: evenly mixing lithium acetate, nano ferric oxide and ammonium dihydrogen phosphate with the molar ratio of 2:1:1 into a water-ethanol solution containing 10% acetic acid to prepare a solution with the solute content of 5-30%, thus obtaining the fluid A.

8. The method for preparing solid spherical lithium iron phosphate by coupling the micro-fluidic technology with the gel method according to claim 6, wherein in step S200, the silicone oil is injected into the continuous fluid channel (110) at a rate of 10-500 μ L/h, and the fluid A is injected into the dispersed fluid channel (120) at a rate of 0.1-100 μ L/h.

9. The method for preparing solid spherical lithium iron phosphate by coupling the micro-fluidic technology with the gel method according to claim 8, wherein the silicone oil is injected into the continuous fluid channel (110) at a rate of 15 μ L/h, and the fluid A is injected into the dispersed fluid channel (120) at a rate of 100 μ L/h.

10. The method as claimed in claim 6, wherein the sintering temperature of the gel particles in step S400 is 1800 ℃ below 1000 ℃.

Images