Method for preparing solid electrolyte for lithium ion battery
Technical Field
The invention relates to the field of lithium batteries and the like, in particular to a method for preparing a solid electrolyte for a lithium ion battery.
Background
Since the first commercialization in the 90 s of the 20 th century, lithium ion batteries have been widely used in various fields such as mobile communication, digital products, and unmanned aerial vehicles due to their advantages of high energy density, large output power, no memory effect, environmental friendliness, and excellent cycle performance.
Currently, most commercial lithium ion batteries widely use liquid organic electrolytes, and meanwhile, a plurality of problems are also exposed. Firstly, the strict requirements on the packaging process bring about the limitation of the reduction of the battery volume; secondly, the liquid or gel electrolyte belongs to flammable and explosive organic matters, so that potential safety hazards exist; and thirdly, the liquid electrolyte is easy to participate in electrode reaction to destroy the electrode structure.
Solid electrolyte energy diffusion filmThe defects of liquid or gel electrolytes are compensated, but the development bottleneck of solid electrolytes is that the solid electrolytes have low ionic conductivity and cannot reach commercial conductivity (10)-3S/cm) standard. Currently, of the many solid oxide electrolytes, those with conductivities approaching commercial levels are lithium lanthanum titanyl and lithium lanthanum zirconyl.
Among the methods for synthesizing lithium lanthanum titanium oxide and lithium lanthanum zirconium oxide, the solid phase method is the first choice for the mass production process because of the advantages of simple equipment requirement, low raw material cost, environment-friendly preparation process and the like. The reaction activity of the micron-sized raw materials is low, and impurities are easy to generate; the nano-grade raw materials can reduce the synthesis temperature and improve the product purity. However, the nano material is generally expensive, so that the manufacturer is prohibited.
Disclosure of Invention
The purpose of the invention is: the method for preparing the solid electrolyte for the lithium ion battery is provided, and the material mixing is uniform, the particle size of the raw material is reduced, the activity of the raw material in the solid phase reaction is increased, the crystallinity of the final product is improved, and the cost is reduced.
The technical scheme for realizing the purpose is as follows: a method of making a solid state electrolyte for a lithium ion battery comprising the steps of: step S1) selecting a kind of solid electrolyte; step S2), weighing micron-sized raw material components for preparing the solid electrolyte and ethanol; the mass ratio of the total raw materials mixed by the raw material components to the ethanol is 1:1-1: 5; step S3) mixing the raw materials with the ethanol to obtain a mixed material, stirring and sanding the mixed material through zirconium balls; step S4), heating and keeping the temperature at 80-200 ℃, and drying to obtain fluffy dry powder; step S5) grinding the dry powder; and step S6), calcining the dry powder, controlling the calcining temperature at 900-1200 ℃, calcining for 1-3 times, and drying the calcined product after sanding each time to obtain the primary solid electrolyte.
In a preferred embodiment of the present invention, the step S6) is followed by a step S7) of sanding the primary solid electrolyte product with zirconium balls to obtain a final solid electrolyte product with a particle size distribution.
In a preferred embodiment of the present invention, the solid electrolyte includes one of lithium lanthanum titanium oxide and lithium lanthanum zirconium oxide.
In a preferred embodiment of the present invention, the raw material components of the lithium lanthanum titanium oxide include lithium carbonate, lanthanum oxide and titanium oxide, and the lithium carbonate, the lanthanum oxide and the titanium oxide are weighed according to a ratio of the number of molecules in the lithium lanthanum titanium oxide molecular formula, where the lithium lanthanum titanium oxide molecular formula is Li0.35La0.55TiO3Wherein, Li, La, Ti, 7, 11, 20.
In a preferred embodiment of the present invention, the raw material components of the lithium lanthanum zirconium oxide include lithium carbonate, lanthanum oxide, zirconium oxide; weighing the lithium carbonate, the lanthanum oxide and the zirconium oxide according to the molecular ratio in the molecular formula of the lithium lanthanum zirconium oxide; the molecular formula of the lithium lanthanum zirconium oxygen is Li7La3Zr2O12Wherein the molecular ratio of Li to La to Zr is 7 to 3 to 2.
In a preferred embodiment of the present invention, if the solid electrolyte is lithium lanthanum zirconium oxide, in the step S2), a certain amount of lithium carbonate is further weighed, and the mass of the lithium carbonate accounts for 1% to 15% of that of the lithium carbonate in the raw material composition.
In a preferred embodiment of the present invention, if the solid electrolyte is lithium lanthanum zirconium oxide, in the step S2), a certain amount of alumina is further weighed as a sintering aid, wherein the molecular ratio La: Zr ═ 2: 0.1-0.5.
In a preferred embodiment of the present invention, in the step S3), the rotation speed of the zirconium ball is 100rpm to 3000rpm, the diameter of the zirconium ball is 0.2mm to 1.2mm, and the sanding time is controlled to be 2h to 48 h.
In a preferred embodiment of the present invention, in the step S6), the calcination time is 2h to 20 h.
The invention has the advantages that: according to the method for preparing the solid electrolyte for the lithium ion battery, disclosed by the invention, the material mixing is uniform, the particle size of the raw material is reduced, the activity of the raw material in a solid-phase reaction is increased, and the crystallinity of a final product is improved. The method greatly reduces the raw material cost and the energy consumption of solid-phase reaction synthesis while improving the purity and quality of the product.
Drawings
The invention is further explained below with reference to the figures and examples.
FIG. 1 shows the XRD spectra of lithium lanthanum titanium oxide finally obtained in examples 1, 2 and 3.
FIG. 2 shows the Nyquist spectra at room temperature for sintering the lithium lanthanum titanyl powders obtained in examples 1, 2 and 3 to prepare ceramics. Figure 3, examples 4 and 5 finally obtain lithium lanthanum zirconium oxygen XRD spectra.
Detailed Description
The following description of the embodiments refers to the accompanying drawings for illustrating the specific embodiments in which the invention may be practiced.
A method of making a solid state electrolyte for a lithium ion battery comprising the steps of: step S1) selecting a kind of solid electrolyte; the solid electrolyte comprises one of lithium lanthanum titanium oxide and lithium lanthanum zirconium oxide.
Step S2), weighing micron-sized raw material components for preparing the solid electrolyte and ethanol; the mass ratio of the total raw materials mixed by the raw material components to the ethanol is 1:1-1: 5. The raw material components of the lithium lanthanum titanium oxide comprise lithium carbonate, lanthanum oxide and titanium oxide, and the lithium carbonate, the lanthanum oxide and the titanium oxide are weighed according to the molecular number ratio in the lithium lanthanum titanium oxide molecular formula, wherein the lithium lanthanum titanium oxide molecular formula is Li0.35La0.55TiO3Wherein, Li, La, Ti, 7, 11, 20.
The raw material components of the lithium lanthanum zirconium oxide comprise lithium carbonate, lanthanum oxide and zirconium oxide; weighing the lithium carbonate, the lanthanum oxide and the zirconium oxide according to the molecular ratio in the molecular formula of the lithium lanthanum zirconium oxide; the molecular formula of the lithium lanthanum zirconium oxygen is Li7La3Zr2O12Wherein the molecular ratio of Li to La to Zr is 7 to 3 to 2.
If the solid electrolyte is lithium lanthanum zirconium oxide, in the step S2), a certain amount of lithium carbonate is further weighed, and the mass of the lithium carbonate accounts for 1% -15% of that of the lithium carbonate in the raw material components.
If the solid electrolyte is lithium lanthanum zirconium oxide, in the step S2), a certain amount of alumina is further weighed as a sintering aid, wherein the molecular ratio La: Zr ═ 2: 0.1-0.5.
Step S3) mixing the raw materials with the ethanol to obtain a mixed material, stirring and sanding the mixed material through zirconium balls; the rotating speed of the zirconium balls is 100rpm to 3000rpm, the diameter of the zirconium balls is 0.2mm to 1.2mm, and the sanding time is controlled to be 2h to 48 h.
Step S4), heating and keeping the temperature at 80-200 ℃, and drying to obtain fluffy dry powder.
Step S5) grinding the dry powder;
and step S6), calcining the dry powder, controlling the calcining temperature to be 900-1200 ℃, the calcining time to be 2-20 h, and the calcining times to be 1-3, wherein the calcined product needs to be sanded and then dried, so as to obtain the primary solid electrolyte.
Step S7) sanding the primary solid electrolyte product through zirconium balls to obtain the final solid electrolyte product with the diameter distribution.
Example 1
Step S1) selecting Li-La-Ti-O ceramic0.35La0.55TiO3Ball milling and synthesizing.
Step S2) with the molecular formula Li0.35La0.55TiO3Weighing micron-sized raw materials of lithium carbonate, lanthanum oxide and titanium oxide according to the proportion of Li, La and Ti being 7:11:20, and adding absolute ethyl alcohol according to the proportion of ethyl alcohol to mixed materials being 1.2:1 by mass; step S3), adding zirconium balls with the diameter of 8mm and 5mm, wherein the mass ratio of the zirconium balls to the mixed materials is 1:1, the ball milling speed is 500rpm, and the time is 20 h; step S4), drying the mixed materials at 120 ℃ to obtain mixed dry powder; step S5) grinding the dry powder; step S6), calcining in a high temperature furnace for 2 hours at 1050 ℃ to obtain the primary product of lithium lanthanum titanium oxide powder, marked as a.
And (4) analyzing results: XRD shows that a small amount of impurities exist, and the superstructure is very unobvious, so that the ionic conductivity of the powder is low.
Example 2
Step S1) selecting Li-La-Ti-O ceramic0.35La0.55TiO3Ball milling and synthesizing.
Step 2) using the molecular formula Li0.35La0.55TiO3Weighing micron-sized raw materials of lithium carbonate, lanthanum oxide and titanium oxide according to the proportion of Li, La and Ti which is 7:11: 20; adding absolute ethyl alcohol according to the mass ratio of the ethyl alcohol to the mixed material of 1.2: 1; step 3) additionZirconium balls with the diameters of 8mm and 5mm, wherein the mass ratio of the zirconium balls to the mixed materials is 1:1, the ball milling rotating speed is 500rpm, and the time is 20 hours; step 4), drying the mixed materials at 120 ℃ to obtain mixed dry powder; step 5), grinding the dry powder; and 6) calcining in a high-temperature furnace at 1150 ℃ for 6 hours to obtain a primary product of the lithium lanthanum titanium oxide powder, which is marked as b.
And (4) analyzing results: XRD shows that a small amount of impurities exist, the powder has a certain superstructure, and the ionic conductivity of the powder is improved.
Example 3
Step S1) selecting Li-La-Ti-O ceramic0.35La0.55TiO3Ball milling and synthesizing.
Step S2) with the molecular formula Li0.35La0.55TiO3Weighing micron-sized raw materials of lithium carbonate, lanthanum oxide and titanium oxide according to the proportion of Li, La and Ti which is 7:11: 20; adding absolute ethyl alcohol according to the mass ratio of the ethanol to the mixed material of 1.2:1, and stirring for one quarter to obtain mixed slurry; step S3), continuously stirring the mixed slurry, and simultaneously, starting sanding at the rotating speed of 2000rpm, wherein the diameter of the zirconium ball is less than 0.4mm, and the sanding time is about 10 h; step S4), drying the mixed materials at 120 ℃ to obtain mixed dry powder; step S5) grinding the dry powder; step S6), calcining in a high-temperature furnace for 2 hours at 1050 ℃ to obtain a pure-phase lithium lanthanum titanium oxide primary product with a superstructure, which is marked as c; step S7) may finally control the lithium lanthanum titanium oxide particles D50 within the corresponding interval by sanding according to the customer' S needs.
And (4) analyzing results: XRD shows that the powder is relatively pure, the superstructure is relatively obvious, and the ionic conductivity of the powder is relatively high.
Example 4
Step S1) selecting Li-La-Zr-O ceramic Li7La3Zr2O12Ball milling and synthesizing.
Step S2) with the molecular formula Li7La3Zr2O12Weighing micron-sized raw materials of lithium carbonate, lanthanum oxide, zirconium oxide and aluminum oxide according to the proportion of Li, La, Zr and Al being 7.7, 3, 2 and 0.3, wherein the lithium carbonate is excessive by 10 percent, and the aluminum oxide is taken as a sintering aid; adding absolute ethyl alcohol according to the mass ratio of the ethyl alcohol to the mixed material of 1.2: 1; step S3) adding zirconium balls with diameters of 8mm and 5mm, mixing zirconium ballsThe material mass ratio is 1:1, the ball milling rotation speed is 500rpm, and the time is 20 h; step S4), drying the mixed materials at 120 ℃ to obtain mixed dry powder; step S5) grinding the dry powder; step S6), placing the powder into a high-temperature furnace for 2 times of calcination, calcining for 12 hours at 900 ℃, adding absolute ethyl alcohol according to the mass ratio of ethyl alcohol to mixed material being 1.2:1, ball-milling for 8 hours, drying, and calcining for 30 hours at 1200 ℃ to obtain a primary product of lithium lanthanum zirconium oxygen powder, which is marked as d.
And (4) analyzing results: XRD shows that the powder is relatively pure, but the temperature is relatively high, and lithium element is seriously volatilized, so that the ionic conductivity of the powder is relatively low.
Example 5
Step S1) selecting Li-La-Zr-O ceramic Li7La3Zr2O12Ball milling and synthesizing.
Step S2) with the molecular formula Li7La3Zr2O12Weighing micron-sized raw materials of lithium carbonate, lanthanum oxide, zirconium oxide and aluminum oxide according to the proportion of Li, La, Zr and Al being 7.7, 3, 2 and 0.3, wherein the lithium carbonate is excessive by 10 percent, and the aluminum oxide is taken as a sintering aid; adding absolute ethyl alcohol according to the mass ratio of the ethyl alcohol to the mixed material of 1.2: 1; step S3), stirring for one quarter to obtain mixed slurry; continuously stirring the mixed slurry, and simultaneously, starting sanding at the rotating speed of 2000rpm, wherein the diameter of a ground zirconia ball is less than 0.4mm, and the sanding time is about 10 hours; step S4), drying the mixed materials at 120 ℃ to obtain mixed dry powder; step S5) grinding the dry powder; step S6), placing the mixture into a high-temperature furnace for 2 times of calcination, calcining for 12 hours at 900 ℃, adding absolute ethyl alcohol according to the mass ratio of ethyl alcohol to mixed materials being 1.5:1, sanding for 6 hours, drying, and calcining for 20 hours at 1100 ℃ to obtain a primary lithium lanthanum zirconium oxide powder with a pure cubic phase, wherein the mark is e; step S7) may finally control the lithium lanthanum zirconium oxygen particles D50 within the corresponding interval by sanding according to the customer' S needs.
And (4) analyzing results: XRD shows that the powder is relatively pure, cubic phase is obvious, and the ionic conductivity of the powder is relatively high.
As shown in Table 1, Table 1 is a numerical table of the electrical conductivity of each of the first solid electrolyte articles a to e of examples 1 to 5.
The present invention is not limited to the above preferred embodiments, and any modifications, equivalent substitutions and improvements made within the spirit and principle of the present invention should be included in the protection scope of the present invention.