KR102568998B1 - Method for manufacturing lithium bis(oxalato)borate - Google Patents

Abstract

A method for producing lithium bis(oxalato)borate (LiBOB) is provided. According to this, it is possible to obtain lithium bis(oxalato)borate with high purity and high yield while reducing man-hours and manufacturing time.

Description

Method for manufacturing lithium bis(oxalato)borate {Method for manufacturing lithium bis(oxalato)borate}

The present invention relates to a method for producing lithium bis (oxalato) borate (LiBOB), and more particularly, to a method for producing lithium bis (oxalato) borate capable of obtaining high-purity and high-yield lithium bis (oxalato) borate will be.

Lithium ion batteries are widely used charge/discharge batteries because of their high energy density, high operating voltage, memory function and long service life. A lithium secondary battery is composed of a cathode active material (cathode), an anode active material (anode), a separator (separator), and an electrolyte (electrolyte).

The cathode active material is a source of lithium ions, releases lithium ions as an oxidation reaction occurs during charging, and absorbs lithium ions as a reduction reaction occurs during discharging. In addition, the negative electrode active material absorbs lithium ions and electrons during charging and releases lithium ions and electrons during discharging. A lithium ion battery uses the energy difference between the positive electrode active material and the negative electrode active material. During discharge, lithium ions of the negative electrode active material are voluntarily inserted into the positive electrode active material having a relatively low chemical energy level through an electrolyte. It serves as a power source while flowing, and charging refers to a process in which lithium ions are stored as an anode active material by making the energy level of the cathode active material high through a charger, as opposed to the above-described discharging.

On the other hand, since high ion transport between the two electrodes is required to obtain excellent battery performance, it is very important to select an optimal electrolyte. Currently, most commercial lithium-ion batteries use lithium hexafluorophosphate (LiPF ₆ ) as a conductive salt included in the electrolyte, which is easily dissolved in an aprotic solvent and has high conductivity. It becomes an electrolyte with a high level of electrochemical stability, so it has essential conditions for use in high-energy batteries.

However, the commonly used LiPF ₆ induces cationic polymerization of the solvent due to its low thermal stability or reacts with moisture to liberate corrosive hydrofluoric acid, resulting in poor handling due to toxicity and corrosiveness. There is a problem that causes partial dissolution of a transition metal oxide (eg, LiMn ₂ O ₄ ), thereby adversely affecting charge/discharge cycle stability.

Accordingly, development of stable conductive salts is being actively carried out, and one of them is lithium bis(oxalato)borate (LiBOB). LiBOB is well soluble in aprotic solvents and has the advantage of being electrochemically stable, but conventional The LiBOB manufacturing method of was limited in its application as a secondary battery electrolyte due to its low purity. In addition, the conventional manufacturing method has problems in that the number of man-hours in the manufacturing process increases, the manufacturing time is extended, and the manufacturing cost increases as various types of purification solvents are used to solve the purity problem. In addition, various purification solvents used may act as another impurity, so there is a limit to increasing the purity.

Republic of Korea Patent Publication No. 10-2008-0000595

The present invention was devised in view of the above points, and by reducing the number of man-hours in the manufacturing process and the number of materials used in the process, the manufacturing time is shortened, and the manufacturing cost is reduced while removing impurities to obtain high-purity and high-yield lithium bis An object of the present invention is to provide a method for producing lithium bis(oxalato)borate capable of obtaining (oxalato)borate.

Another object of the present invention is to provide the high-purity lithium bis(oxalato)borate prepared according to the present invention as an electrolyte additive for a secondary battery.

In order to solve the above problems, the present invention (1) reacts a reactant including a lithium compound, a boron compound, and oxalic acid or oxalate in a first solvent containing an alcohol having a boiling point of 95 ° C or higher to obtain lithium bis (oxalato) Provided is a method for preparing lithium bis(oxalato)borate, which includes synthesizing and crystallizing borate (LiBOB), and (2) purifying and recrystallizing the crystallized LiBOB.

According to an embodiment of the present invention, the lithium compound is one selected from the group consisting of lithium hydroxide monohydrate (LiOH H ₂ O), lithium hydroxide (LiOH), lithium carbonate (Li ₂ CO ₃ ) and lithium oxalate. Including the above, the boron compound may include at least one selected from the group consisting of boric acid (H ₃ BO ₃ ), boric acid (HBO ₂ ) and boron oxide (B ₂ O ₃ ).

In addition, the alcohol may have a boiling point of 110° C. or more and have 5 or less carbon atoms.

Also, the first solvent may not contain water.

In addition, the alcohol may include one or more of propanol, butanol, and pentanol.

In addition, step (1) is 1-1) injecting a reactant and a first solvent including oxalic acid dehydrate, boric acid, and lithium hydroxide monohydrate into the reactor, 1-2) replacing the air inside the reactor with nitrogen gas, 1-3) heating the inside of the reactor to a temperature of 90 to 110 ° C, adding steam at 105 to 120 ° C, bubbling the reactant solution and filtering obtaining a first product containing the synthesized LiBOB, and 1-4) concentrating and then drying the first product to obtain a LiBOB crystal.

In addition, the yield of LiBOB crystals obtained after performing step (1) may be 97 to 99%.

In addition, step (2) includes 2-1) dissolving and purifying the crystallized LiBOB with a second solvent including a solvent represented by the following Chemical Formula 1, and 2-2) dissolving and purifying the LiBOB purified product in a solvent represented by the following Chemical Formula 2 It may include the step of recrystallizing with a third solvent containing.

[Formula 1]

Where n is an integer from 1 to 4.

[Formula 2]

where a and b are each independently an integer from 0 to 3.

In addition, the solvent represented by Formula 2 may be a solvent in which a and b in Formula 2 are independently integers of 0 to 2, and the sum of a and b satisfies 3 or less.

In addition, the solvent represented by Chemical Formula 1 may be a solvent in which n is 1 in Chemical Formula 1, and the solvent represented by Chemical Formula 2 may be a solvent in which a and b are respectively 0 in Chemical Formula 2.

In addition, the purity of the recrystallized LiBOB may be 99.80 to 99.99%.

The method for producing lithium bis(oxalato)borate according to the present invention increases the yield of the obtained lithium bis(oxalato)borate while reducing the number of man-hours in the manufacturing process and the type and number of materials used in the process to shorten the manufacturing time and manufacture It makes it possible to obtain lithium bis(oxalato)borate of high purity while reducing cost. Accordingly, the high-yield lithium bis(oxalato)borate can be widely applied as an electrolyte additive for secondary batteries.

Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art can easily implement the present invention. This invention may be embodied in many different forms and is not limited to the embodiments set forth herein.

Lithium bis(oxalato)borate according to an embodiment of the present invention is obtained by (1) reacting a reactant including a lithium compound, a boron compound, and oxalic acid or oxalate in a first solvent containing an alcohol having a boiling point of 95° C. or higher. It may be prepared by synthesizing and crystallizing lithium bis(oxalato)borate (LiBOB), and (2) purifying and recrystallizing the crystallized LiBOB.

First, in step (1) according to the present invention, lithium bis (oxalato) borate ( LiBOB) is synthesized and crystallized.

A lithium compound and a boron compound as reactants may be used without limitation in known compounds used to synthesize lithium bis(oxalato)borate. For example, the lithium compound may include at least one selected from the group consisting of lithium hydroxide monohydrate (LiOH H ₂ O), lithium hydroxide (LiOH), lithium carbonate (Li ₂ CO ₃ ) and lithium oxalate, Preferably, lithium hydroxide monohydrate (LiOH·H ₂ O) may be included. In addition, the boron compound may include at least one selected from the group consisting of boric acid (H ₃ BO ₃ ), boric acid (HBO ₂ ) and boron oxide (B ₂ O ₃ ), preferably boric acid (H ₃ BO ₃ ) may be included. In addition, preferably, oxalic acid may be included among oxalic acid and oxalate, and through this, there is an advantage in that an additional cation removal step can be omitted when oxalic acid is used.

In addition, the reactant may include 12 to 18 parts by weight of a lithium compound and 20 to 26 parts by weight of a boron compound based on 100 parts by weight of oxalic acid, more preferably 14 to 16 parts by weight of a lithium compound and 22 parts by weight of a boron compound. ~ 24 parts by weight. If the content of the lithium compound is less than 12 parts by weight and/or the content of the boron compound is less than 20 parts by weight, the yield of lithium bis(oxalato)borate may decrease. In addition, if the content of the lithium compound exceeds 18 parts by weight and/or the content of the boron compound exceeds 26 parts by weight, the purity of the synthesized lithium bis(oxalato)borate due to unreacted materials may be reduced. The number or input amount of solvents used in step (2) may increase, and there is a concern that the number of man-hours and time required for purification may increase.

The above reactants are synthesized into lithium bis(oxalato)borate in the first solvent containing an alcohol having a boiling point of 95°C or higher. The first solvent includes an alcohol having a boiling point of 95 ° C or higher as the main solvent, and an alcohol having a boiling point of 95 ° C or higher is a reaction solvent that has excellent solubility in the above-mentioned reactants, especially starting materials, and is advantageous in homogenizing them, bis (oxal In the process of synthesizing leito)borate, it is advantageous to increase the reaction rate and acts as an azeotropic solvent to remove water generated during the reaction, so that the forward reaction of synthesizing the reactant into bis(oxalato)borate occurs better, thereby increasing the yield Simultaneously synthesized bis(oxalato)borate may be advantageous in improving purity by significantly lowering the content of unreacted reactants. In addition, alcohol minimizes the synthesis of by-products that may be produced during the synthesis of bis(oxalato)borate, in particular, borolane diones having oxalic acid attached to only one side, or has high solubility even when synthesized. It may be more advantageous to remove it. If a solvent other than alcohol, for example, an organic solvent such as toluene, is used as the reaction solvent, it is difficult to achieve a sufficient yield compared to the case of using alcohol as a solvent, and the amount of by-products produced increases or is not easily removed. The solvent itself may cause a decrease in purity. In addition, an additional purification process may be added to increase the purity.

The alcohol has a boiling point of 95 ° C. or higher, preferably 110 ° C. or higher, and through this, there is an advantage in that the temperature is usable even though it is high temperature. In addition, when the boiling point of alcohol is less than 95 ° C., it may be difficult to achieve the object of the present invention, such as problems such as yield reduction due to the generation of a large amount of unreacted substances. Among the alcohols, primary alcohols, polyhydric alcohols, unsaturated aliphatic alcohols and/or aliphatic cyclic alcohols having a boiling point of 95° C. or higher may be used without limitation. However, the alcohol having a boiling point of 95 ° C or higher may preferably have 5 or less carbon atoms, and if the number of carbon atoms exceeds 5, the solubility in the reactants is lowered, and an increase in temperature is unavoidable to dissolve the reactants, resulting in manufacturing time, There is a problem of increasing cost, and there is a concern that the amount of unreacted reactants increases. In particular, when the number of carbon atoms exceeds 5, it is not easy to remove water generated during the synthesis of bis (oxalato) borate, so it is difficult to dominate the forward reaction in which bis (oxalato) borate is synthesized, thereby achieving a sufficient yield. It can be difficult. In addition, when the carbon number exceeds 5, the viscosity increases, which may interfere with stirring efficiency and distillation, and there is a concern that the use time of the reactor may be extended during mass production.

According to one embodiment of the present invention, an alcohol having a boiling point of 95 ° C or higher is advantageous as a solvent of the present invention, such as n-propanol, n-butanol, n-pentanol, cyclopentanol, tert-pentaol, and allyl alcohol (allyl alcohol). ), propen-2-ol, cyclopropanol, cyclobutanol, 2-buten-1-ol, 3-buten-2-ol, crotyl alcohol, 2-methyl-3-butyn-2-ol (2-METHYL-3-BUTYN-2-OL), 2-methyl-2-buten-1-ol, 2-methyl-3-buten-2-ol, cis-2-penten-1-ol, trans- The group consisting of 3-penten-2-ol, 3-butyn-1-ol, 1-penten-3-ol, 3-cyclopenten-1-ol, 4-penten-2-ol and 4-penten-1-ol It may include at least one selected from, and more preferably at least one selected from the group consisting of n-propanol, n-butanol, n-pentanol, cyclopentanol, tert-pentaol, cyclobutanol and cyclopropanol. may include, more preferably n-propanol, n-butanol, n-pentanol It may include one or more of them, and for example, it may include one of n-propanol, n-butanol, and n-pentaol.

In addition, according to an embodiment of the present invention, the first solvent may further include a known solvent used in the production of bis(oxalato)borate in addition to alcohol having a boiling point of 95°C or higher. However, as described above, when using a heterogeneous organic solvent, the yield increase may be insignificant and the production of by-products may increase, so it is advantageous to minimize the content even if it is further included. In addition, when water is contained in the first solvent, it is advantageous to minimize the formation of by-products, but it is not easy to remove water, and thus, the increase in purity may be limited. Accordingly, the content of heterogeneous solvents that may be included in the first solvent other than alcohol having a boiling point of 95° C. or higher is 10% by weight or less, more preferably 5% by weight or less, and even more preferably 3% by weight based on the total weight of the first solvent. Hereinafter, more preferably, a heterosolvent such as water may not be included.

The first solvent may be added in an amount of 100 to 200 parts by weight, more preferably 120 to 160 parts by weight, based on 100 parts by weight of oxalic acid or oxalate, and through this, it may be more advantageous to achieve the object of the present invention.

According to an embodiment of the present invention, step (1) is step 1-1), wherein the above-mentioned reactant and first solvent are introduced into the reactor, 1-2) the air inside the reactor is replaced with nitrogen gas, 1 -3) After raising the temperature of the inside of the reactor to 80 ~ 130 ℃, for example, 90 ~ 110 ℃, and then adding steam at 105 ~ 120 ℃, bubbling the reactant solution through an inert gas and filtering the synthesized LiBOB obtaining a first product containing the first product, and 1-4) concentrating and then drying the first product to obtain LiBOB crystals.

In step 1-1), preferably, reactants including oxalic acid dehydrate, boric acid, and lithium hydroxide monohydrate and a first solvent may be introduced as reactants.

Next, step 1-2) is a step of replacing the air inside the reactor with nitrogen gas, preferably by blowing nitrogen gas for 20 to 60 minutes at a temperature inside the reactor of 45 to 55 ° C, more preferably 45 to 50 ° C. By doing so, the air inside the reactor can be replaced with nitrogen gas.

After that, in step 1-3), the temperature of the inside of the reactor is raised to 80 ~ 130 ℃, for example, 90 ~ 110 ℃ to solution the reactant, and then steam at 105 ~ 120 ℃ is added and the reactant solution is bubbled through an inert gas After ringing, a step of obtaining a primary product containing the synthesized LiBOB by filtering may be performed.

First, the solubility of the reactant in the first solvent can be increased by increasing the temperature inside the reactor. It is preferable to raise the temperature to a temperature 5 to 40 ° C lower than the boiling point of the first solvent. Considering the boiling point of one solvent, the temperature of the reactor may be increased to 80 to 130° C., for example, to 90 to 110° C. If the temperature of the first reactor is raised to a temperature lower than 80 ° C, the amount of unreacted materials may increase and the yield may decrease, and when the temperature is raised to exceed 130 ° C, decomposition of the starting material may occur.

In addition, steam at 105 to 120 ° C. may be introduced into the reactor after the temperature inside the reactor is raised. If the temperature of the steam is less than 105 ° C, the yield and purity of the primary product may decrease, and if it exceeds 120 ° C, the temperature in the reactor becomes too high and the reaction proceeds rapidly, resulting in a problem with stability.

In addition, a reflux reaction can be performed by bubbling a gas into the reactant solution. The bubbling gas uses an inert gas, and the inert gas may include at least one selected from the group consisting of nitrogen, helium, neon, argon, krypton, xenon, and radon, and preferably may include nitrogen. there is. When gas is bubbling, it is possible to efficiently remove moisture, impurities and various gases coordinating with lithium ions after the reaction by weakening the surface area bonding distance between the first solvent and lithium of the first product, resulting in high-purity bis(oxal) It may be advantageous to obtain leito)borates. In addition, the reflux reaction may be performed for 1 to 3 hours, but is not limited thereto. Meanwhile, steps 1-3) may be performed using a generally used reflux reaction system.

In addition, a filtration process may be further performed after step 1-3). The filtration process may perform filtration of the primary product in the reactant solution in which the reaction is completed by a general filtration method in the art, and for example, the reactant solution in which the reaction is completed may be cooled to 15 to 35 ° C., more preferably After cooling to 25 ~ 30 ° C., the reactant solution in which the reaction has been cooled can be solid / liquid separated using a conventional method such as a filter medium to obtain a primary product.

Next, 1-4) the primary product may be concentrated and then dried to obtain LiBOB crystals.

The concentration may be performed by a known concentration method used in the art, and for example, concentration under reduced pressure may be performed under temperature conditions of 400 to 600 torr and 85 to 95 ° C.

In addition, high vacuum concentration may be further performed after concentration under reduced pressure, and the high vacuum concentration may be performed using a vacuum concentrator under a pressure of 1Х10 ^-1 ~ 1Х10 ^-2 torr and 110 ~ 140 ℃ more preferably 110 ~ 125 ℃.

As described above, the concentrated primary product may be obtained as LiBOB crystals after performing a drying process, and the drying process may be by a drying process and drying conditions known in the art, so the present invention is not particularly limited thereto. don't In addition, a cooling process may be further performed before the drying process, but is not limited thereto.

The yield of the primary product in a crystalline state obtained through the above-described step (1) may be 95 to 99%, more preferably 96 to 97%. In addition, the purity of the obtained primary product in a crystalline state may be 95.0% or more.

Next, steps of purifying and recrystallizing the crystallized LiBOB are performed as step (2) according to the present invention.

Step (2) includes 2-1) dissolving and purifying the crystallized LiBOB with a second solvent containing a solvent represented by Formula 1 below, and 2-2) dissolving and purifying the purified LiBOB product in a solvent represented by Formula 2 below. It may be performed including the step of recrystallizing with a third solvent containing

[Formula 1]

Where n is an integer from 1 to 4.

[Formula 2]

where a and b are each independently an integer from 0 to 3.

As step 2-1), a step of dissolving and purifying the crystallized LiBOB with a second solvent including the solvent represented by Formula 1 may be performed. Step 2-1) is a first purification process for removing foreign substances contained in the LiBOB crystal obtained through step (1), and a second solvent including the solvent represented by Formula 1 corresponding to the purification solvent may be used, More preferably, the second solvent may be composed of a solvent represented by Formula 1, and through this, the solvent cost can be reduced by reducing the types of purification solvents used, and furthermore, the removal of each purification solvent accompanying the increase in the types of purification solvents Man-hours in the process can be reduced. In addition, compared to other purification solvents, the solvent represented by Formula 1 does not have a high boiling point, so it has the advantage of shortening the drying time and lowering the heating temperature, and may be advantageous in obtaining a target product of higher purity. For example, alkylene carbonate, known as a solvent used in the primary purification process, dissolves LiBOB and removes foreign substances, but its high boiling point increases the drying time in the purification process, and its high heating temperature increases the manufacturing cost and prolongs the manufacturing time. It can be. In addition, in order to remove the remaining alkylene carbonate contained in the obtained primary purification product, a step of adding a dioxane solvent is necessarily further involved, thereby increasing the number of solvents used in step (1) and increasing the number of man-hours There is a concern that the additional solvent of dioxanes has a relatively high freezing point, so it is difficult to maintain a liquid phase in winter, so it is not easy to perform the process depending on the season.

In addition, the second solvent used in step 2-1) may be added in an amount of 220 to 420 parts by weight, more preferably 260 to 350 parts by weight, based on 100 parts by weight of oxalic acid added in step (1). On the other hand, the input amount of the second solvent used is smaller than that of the purification solvent in a general purification process, and there is an advantage in that the solvent cost of the purification solvent used is reduced.

On the other hand, the simplification and reduction of the amount of the purification solvent used in step 2-1) is due to the use of an alcohol having a boiling point of 95 ° C. or higher as the first solvent in step (1), resulting in the primary product crystal obtained in step (1). This is due to the decrease in the content of unreacted or by-products, and if the solvent used in step (1) is a non-aqueous solvent known to be used in LiBOB synthesis rather than alcohol, simplification and reduction in the amount of purification solvent in step 2-1) can be difficult

The solvent represented by Chemical Formula 1 used in the step 2-1) may more preferably be a solvent in which n is an integer of 1 to 2, and more preferably may be a solvent in which n is 1, and through this, the present invention It may be more advantageous to achieve the purpose of

In addition, step 2-1) may be performed at a temperature of 50 to 65° C. for 30 to 90 minutes, but is not limited thereto.

Thereafter, the filtrate is obtained by filtering using a known method, and then a process of concentration may be performed. At this time, the concentration may be, for example, vacuum concentration, and may be performed at a pressure of 5 torr to 300 torr, preferably at a pressure of 5 torr to 150 torr, which may be advantageous in achieving the object of the present invention. .

Subsequently, as step 2-2), a step of recrystallizing the purified LiBOB with a third solvent including a solvent represented by Chemical Formula 2 may be performed.

[Formula 2]

where a and b are each independently an integer from 0 to 3.

In step 2-2), a third solvent is used as the recrystallization solvent. The third solvent includes a solvent represented by Chemical Formula 2 below, and more preferably, a solvent represented by Chemical Formula 2. In addition, more preferably, in the solvent represented by Formula 2, a and b are each independently integers of 0 to 2, but the sum of a and b may be 3 or less, and more preferably, a and b are each independently It may be an integer of 0 to 1, more preferably, both a and b may be 0, through which the bis (oxalato) borate obtained through step 2-1) is partially dissolved and the remaining unreacted material, e.g. For example, oxalic acid can be additionally dissolved and removed and crystallized at the same time, so that higher purity bis(oxalato)borate crystals can be obtained again. In addition, in the case of the solvent represented by Chemical Formula 2 in which both a and b are 0, it is advantageous because it has little effect on the lithium secondary battery even when a trace amount remains in the finally obtained LiBOB crystal as a kind of solvent used in a lithium secondary battery.

In addition, the third solvent used in step 2-2) may be added in an amount of 220 to 420 parts by weight, more preferably 260 to 350 parts by weight, based on 100 parts by weight of oxalic acid added in step (1). may be advantageous to achieve the purpose of

Step 2-2) may be performed at a temperature of 50 to 65° C. for 30 to 90 minutes, but is not limited thereto.

In addition, solid/liquid separation may be performed after step 2-2) using a known method to obtain solid recrystallized bis(oxalato)borate.

In addition, a drying process may be further performed thereafter, and at this time, drying may be performed at a temperature of 140 to 180 ° C. for 12 to 20 hours, but is not limited thereto.

The recrystallized LiBOB finally obtained through the above-described step 2-2) may have a yield of 83% or more, more preferably 85% or more, even more preferably 90% or more, and more preferably 90 to 95% can be In addition, the purity may be 98.0% or more, more preferably 98.5% or more, even more preferably 99.0% or more, still more preferably 99.5 to 99.99%, or 99.80 to 99.99% or 99.99% or more.

The bis(oxalato)borate obtained by the above-described manufacturing method can be used for various known uses, preferably as an electrolyte additive for secondary batteries, and is suitable for use as a non-aqueous electrolyte additive for secondary batteries, for example. .

Although the present invention will be described in more detail through the following examples, the following examples are not intended to limit the scope of the present invention, which should be interpreted to aid understanding of the present invention.

<Example 1>

17.1 parts by weight of lithium hydroxide monohydrate, 25.1 parts by weight of boric acid, 100 parts by weight of oxalic acid dihydrate in a reactor, which is a four-necked 1000ml reaction flask equipped with a thermometer, a heating device, a distillation concentrating device, and a nitrogen bubble device, Boiling point as the first solvent 150.6 parts by weight of 1-butanol having a temperature of 117.3 ° C was added. After raising the temperature in the reactor to 50 ° C., the air in the reactor was replaced by passing nitrogen gas for 30 minutes. Then, after slowly raising the temperature to 105 ° C., 110 ° C. steam was introduced into the reactor while stirring, and the reaction was refluxed for 1 hour while bubbling nitrogen. Thereafter, a primary product was obtained by filtration, and then concentrated under reduced pressure at 500 torr and about 90° C. to obtain a concentrated product under reduced pressure. Thereafter, the vacuum concentrate was introduced into a vacuum concentrator, the pressure was lowered to about 6Х10 ^-2 torr using a high vacuum booster pump, and then high vacuum concentration was performed at 120 ° C to obtain a vacuum concentrate, and the vacuum concentrate was After cooling, LiBOB crystals having completed step (1) were obtained (yield: 98.1%, purity: 95.7%, moisture content: 500 ppm).

Then, the following process was performed to purify and recrystallize the obtained LiBOB crystals. Specifically, 302 parts by weight of a solvent represented by Chemical Formula 1-1 below was added as a second solvent to 100 parts by weight of LiBOB crystals obtained inside the reactor, the temperature was raised to 60 ° C, and stirring was performed for 1 hour to dissolve the second solvent. A solution in which LiBOB was dissolved was prepared.

[Formula 1-1]

(where n=1)

Thereafter, the solution was filtered and the filtrate was concentrated under vacuum at 150 torr.

Then, based on 100 parts by weight of oxalic acid added to the reactor, 305 parts by weight of a third solvent represented by the following formula 2-1 was added, stirred at 60 ° C for 1 hour, and then filtered through a filter to obtain a solid / liquid. After separation, the solid phase was dried at 160° C. for 15 hours to obtain recrystallized LiBOB which completed step (2) (yield: 91.3%, purity: 99.9%).

[Formula 2-1]

(where a=0, b=0)

<Examples 2 to 13>

It was prepared in the same manner as in Example 1, but the first solvent, the second solvent, and / or the third solvent were changed as shown in Table 1 to obtain recrystallized LiBOB shown in Table 1 below.

<Comparative Examples 1 to 3>

It was prepared in the same manner as in Example 1, but the first solvent was changed as shown in Table 1 below to obtain recrystallized LiBOB as shown in Table 1 below.

<Experimental Example 1>

During the manufacturing process of LiBOB according to Examples and Comparative Examples, the yield and purity of LiBOB crystals obtained after completion of step (1) and the yield and purity of recrystallized LiBOB obtained after completion of step (2) were measured. At this time, the purity was measured through the insoluble content method after dissolving LiBOB in a solvent, and the yield was calculated as the theoretical yield value versus the weight ratio after final drying.

(Level 1 (2) step 1st solvent
Type/boiling point (℃), carbon number LiBOB yield/
water second solvent 3rd solvent LiBOB yield/
water Example 1 1-Butanol/117.3/4 98.3 / 96.7 Formula 1-1 Formula 2-1 91.7 / 99.9 Example 2 1-propanol/97/3 95.8 / 95.1 Formula 1-1 Formula 2-1 89.7 / 99.9 Example 3 1-Pentanol/137/5 93.7 / 94.8 Formula 1-1 Formula 2-1 85.5 / 99.8 Example 4 1-Hexanol/156/6 85.1 / 91.1 Formula 1-1 Formula 2-1 78.3 / 99.8 Example 5 1-Butanol/117.3/4 98.3 / 96.7 Formula 1-2
(n=2) Formula 2-1 90.3 / 99.9 Example 6 1-Butanol/117.3/4 98.3 / 96.7 Formula 1-3
(n=3) Formula 2-1 85.1 / 99.9 Example 7 1-Butanol/117.3/4 98.3 / 96.7 Formula 1-5 (n = 5) Formula 2-1 80.2 / 98.8 Example 8 1-Butanol/117.3/4 98.3 / 96.7 propylene carbonate Formula 2-1 44.6 / 97.8 Example 9 1-Butanol/117.3/4 98.3 / 96.7 dimethyl ether Formula 2-1 36.7 / 97.7 Example 10 1-Butanol/117.3/4 98.3 / 96.7 Tetrohydrofuran (THF) Formula 2-1 58.4 / 98.3 Example 11 1-Butanol/117.3/4 98.3 / 96.7 Formula 1-1 chemical formula 2-2
(a=2,b=1) 83.4 / 99.1 Example 12 1-Butanol/117.3/4 98.3 / 96.7 Formula 1-1 toluene 92.2 / 96.5 Example 13 90% by weight of 1-butanol + 10% by weight of water (DI) 97.4 / 96.1 Formula 1-1 Formula 2-1 90.2 / 99.7 Comparative Example 1 Ethanol/78.3/2 75.6 / 93.0 Formula 1-1 Formula 2-1 66.1 / 99.7 Comparative Example 2 Isopropyl alcohol/82.6/3 77.2 / 93.8 Formula 1-1 Formula 2-1 70.8 / 99.7 Comparative Example 3 Water (DI)/100/0 90.8 / unmeasured Formula 1-1 Formula 2-1 86.2 / unmeasured

As can be seen from Table 1,

It can be seen that in Comparative Examples 1 and 2 using alcohol having a boiling point of less than 95° C. as the first solvent, the yield and purity of LiBOB are significantly lower than those of Examples.

In addition, it can be seen that the yield and / or purity of Examples using alcohol having a boiling point of 95 ° C. or higher as the first solvent is superior to Comparative Example 3 in which water is used as the first solvent.

On the other hand, even when alcohol having a boiling point of 95 ° C. or higher is used as the first solvent, it can be seen that Examples 1 to 3 using an alcohol having a carbon number of 5 or less are superior in yield and purity to Example 4.

In addition, even when alcohol having a boiling point of 95 ° C. or higher is used as the first solvent through Example 1 and Examples 5 to 13, purity and yield according to the second and third solvents used during purification and recrystallization when alcohol is used as alcohol It can be seen that there may be a difference in , and in particular, Example 8 using an alkylcarbonate-based solvent often used as the second solvent or Example 9 using an ether-based solvent had a greatly reduced yield, and was often used as a third solvent. Even in the case of toluene, the yield and purity are lowered, so it can be seen that it is not suitable for obtaining LiBOB with high yield and purity when alcohol with a boiling point of 95 ° C. or higher is used as the reaction solvent.

Although one embodiment of the present invention has been described above, the spirit of the present invention is not limited to the embodiments presented herein, and those skilled in the art who understand the spirit of the present invention may add elements within the scope of the same spirit. However, other embodiments can be easily proposed by means of changes, deletions, additions, etc., but these will also fall within the scope of the present invention.

Claims (10)

(1) Lithium bis(oxalato)borate (LiBOB) is obtained by reacting a reactant including a lithium compound, a boron compound, and oxalic acid or oxalate in a first solvent containing an alcohol having a boiling point of 95° C. or higher and a carbon number of 5 or less. synthesis and crystallization; and
(2) purifying and recrystallizing the crystallized LiBOB; including, wherein step (2)
2-1) dissolving and purifying the crystallized LiBOB with a second solvent containing a solvent represented by Formula 1 below, and 2-2) dissolving and purifying the LiBOB purified product with a third solvent containing a solvent represented by Formula 2 below Method for producing lithium bis(oxalato)borate including the step of recrystallization:
[Formula 1]

where n is an integer from 1 to 4,
[Formula 2]

Here, a and b are each independently an integer from 0 to 3. According to claim 1,
The lithium compound includes at least one selected from the group consisting of lithium hydroxide monohydrate (LiOH H ₂ O), lithium hydroxide (LiOH), lithium carbonate (Li ₂ CO ₃ ) and lithium oxalate,
The boron compound is a lithium bis (oxalato) borate production method comprising at least one selected from the group consisting of boric acid (H ₃ BO ₃ ), boric acid (HBO ₂ ) and boron oxide (B ₂ O ₃ ). delete According to claim 1,
The method for producing lithium bis (oxalato) borate, characterized in that the first solvent does not contain water. According to claim 1,
The alcohol is bis (oxalato) borate production method comprising at least one of propanol, butanol and pentanol. The method of claim 1, wherein step (1)
1-1) introducing a first solvent and reactants including oxalic acid dehydrate, boric acid, and lithium hydroxide monohydrate into a reactor;
1-2) replacing the air inside the reactor with nitrogen gas;
1-3) After raising the temperature of the inside of the reactor to 90 ~ 110 ℃, adding steam at 105 ~ 120 ℃, bubbling the reactant solution and then filtering to obtain a first product containing the synthesized LiBOB; and
1-4) concentrating and drying the primary product to obtain LiBOB crystals; Lithium bis (oxalato) borate production method comprising a. According to claim 1,
A method for producing lithium bis(oxalato)borate wherein the yield of LiBOB crystals obtained after performing step (1) is 97.0 to 99.0%. delete According to claim 1,
The solvent represented by Formula 2 is a lithium bis (oxalato) borate production method in which a and b in Formula 2 are independently integers of 0 to 2, and the sum of a and b satisfies 3 or less. According to claim 1,
The purity of the recrystallized LiBOB is 99.80 to 99.99% lithium bis (oxalato) borate production method.