KR102529105B1 - Method for manufacturing lithium bisoxalatoborate using gas bubble - Google Patents

Abstract

The present invention relates to a method for producing lithium bisoxalatoborate using gas bubbles, and more specifically, by using gas bubbles to efficiently remove moisture, impurities and various gases coordinating with lithium ions after reaction to obtain high purity and It is characterized by producing high quality lithium bisoxalatoborate.

Description

Method for producing lithium bisoxalatoborate using gas bubbles {METHOD FOR MANUFACTURING LITHIUM BISOXALATOBORATE USING GAS BUBBLE}

The present invention relates to a method for producing lithium bisoxalatoborate using gas bubbles, and more specifically, by using gas bubbles to efficiently remove moisture, impurities and various gases coordinating with lithium ions after reaction to obtain high purity and It is characterized by producing high quality lithium bisoxalatoborate.

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. The anode active material absorbs lithium ions and electrons during charging and emits lithium ions and electrons during discharging. The separator functions to separate the cathode active material and the anode active material of the battery to prevent internal short circuit and pass lithium ions so that charging and discharging can occur. The electrolyte provides a passage through which ions reduced or oxidized in the cathode active material and the anode active material can move.

The battery uses the energy difference between the cathode active material and the anode active material. During discharging, lithium ions of the anode active material are voluntarily inserted into the cathode active material having a relatively low chemical energy level through the electrolyte, and at this time, electrons flow to an external wire and serve as a power source. Charging, on the contrary to discharging, is a process in which lithium ions are stored as an anode active material by increasing the energy level of the cathode active material through a charger. As the positive electrode active material contains more lithium ions, the capacity of the battery increases, and the battery life is extended only when the crystal structure of the positive electrode active material is stably maintained according to long-term charging and discharging.

In addition, since high ion transport between both electrodes is required to obtain good battery performance, it is very important to select an optimal electrolyte. Currently, most commercial lithium secondary batteries use lithium hexafluorophosphate (LiPF ₆ ) as a conductive salt included in the electrolyte. This salt has the necessary conditions for use in high-energy batteries. That is, the LiPF ₆ can be easily dissolved in an aprotic solvent, becomes an electrolyte having high conductivity, and has a high level of electrochemical stability.

However, the generally used LiPF ₆ has a disadvantage in that the degree of dissociation between lithium ions and PF ₆ ^-anions is lowered at low temperatures, so that the battery resistance of a secondary battery using the same is rapidly increased and the output is lowered. In addition, LiPF ₆ is separated into LiF and PF ₅ , which makes handling difficult due to toxicity and corrosiveness caused by PF ₅ , and on the other hand, transition metal oxides (eg, LiMn ₂ O ₄ ) used as negative electrodes. cause (partial) dissolution; This causes a problem in that the cycle stability of each electrochemical energy storage is affected.

A non-aqueous electrolyte solution using lithium bisoxalate borate (LiBOB) as an additive of the electrolyte solution has been used to overcome the decrease in electrical characteristics of the lithium secondary battery caused by the electrolyte solution. Korean Patent Publication No. 10-2008-0000595 (January 2, 2008) discloses a non-aqueous electrolyte solution using lithium bisoxalate borate (LiBOB) as an electrolyte additive for a lithium secondary battery, which can improve low-temperature performance. there is. When lithium bisoxalate borate (LiBOB) is used as an additive for an electrolyte solution, the demand for it is increasing because it can solve problems such as performance degradation of a lithium secondary battery caused by a conventional electrolyte solution. Development of a method for producing borate (LiBOB) is required.

KR 10-2008-0000595 A

The present invention has been made to solve the above problems of the prior art, and by using gas bubbles to efficiently remove moisture, impurities and various gases coordinated with lithium ions after reaction, high purity and high quality lithium bisoxal It is to provide a method for producing lithium bisoxalate borate capable of producing leytoborate.

As a technical means for achieving the above-described technical problem, one aspect of the present invention,

mixing oxalic acid dihydrate, a boron compound, a lithium compound, and a solvent, and then reacting by raising the temperature; and removing water generated in the reaction step by vacuum distillation while bubbling gas to the reactant.

The gas may be an inert gas or air.

The inert gas may include at least one selected from the group consisting of nitrogen, helium, neon, argon, krypton, xenon, and radon.

The boron compound may include at least one selected from the group consisting of boric acid (H ₃ BO ₃ ), boron oxide (B ₂ O ₃ ), and boric acid ester (B(OR) ₃ ) (where R is methyl or ethyl). can

The lithium compound is selected from the group consisting of lithium hydroxide monohydrate (LiOH H ₂ O), lithium hydroxide (LiOH), lithium carbonate (Li ₂ CO ₃ ), lithium oxalate and LiOR (where R is methyl or ethyl) One or more may be included.

The solvent is at least one selected from the group consisting of water, propylene carbonate, ethylene carbonate, dimethyl carbonate, ethyl methyl carbonate and diethyl carbonate can include

The solvent may include water and propylene carbonate.

The amount of the propylene carbonate relative to 100 parts by weight of the water may be 50 to 200 parts by weight.

The method for producing the lithium bisoxalate borate may include vacuum distillation while bubbling gas to the reactants to remove water generated in the reaction step; Thereafter, after cooling the reactant from which the water has been removed, first filtering to remove the first impurities; may be further included.

After cooling the reactant from which the water has been removed, adding propylene carbonate and dimethoxyethane to the reaction product and vacuum concentration may be further included.

The method for preparing the lithium bisoxalate borate may include cooling the reactant from which the water has been removed, and then first filtering to remove first impurities; Thereafter, adding dimethoxyethane to the reactant and removing secondary impurities by secondary filtration; may be further included.

The method may further include vacuum-concentrating the dimethoxyethane after removing the secondary impurities.

The method for preparing the lithium bisoxalate borate may include adding dimethoxyethane to the reactant and performing secondary filtration to remove secondary impurities; Thereafter, the step of adding ethylmethyl carbonate to the reactant, precipitating it as a solid by tertiary filtration, and vacuum drying; may be further included.

Another aspect of the present invention provides lithium bisoxalate borate prepared according to the above production method.

Another aspect of the present invention provides an electrolyte for a secondary battery containing the lithium bisoxalate borate.

The method for producing lithium bisoxalatoborate of the present invention uses gas bubbles to efficiently remove moisture, impurities and various gases coordinated with lithium ions after reaction, thereby producing high purity and high quality lithium bisoxalatoborate. There is an effect.

1 is a flow chart showing a method for producing lithium bisoxalate borate of the present invention.
Figure 2 is a flow chart showing a method for producing lithium bisoxalate borate of the present invention.

Hereinafter, the present invention will be described in more detail. However, the present invention can be implemented in many different forms, and the present invention is not limited by the embodiments described herein, and the present invention is only defined by the claims to be described later.

In addition, terms used in the present invention are only used to describe specific embodiments, and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly dictates otherwise. In the entire specification of the present invention, 'include' a certain element means that other elements may be further included without excluding other elements unless otherwise stated.

1 and 2 are flowcharts showing a method for producing lithium bisoxalate borate of the present invention.

Hereinafter, a method for preparing lithium bisoxalate borate according to the present invention will be described with reference to FIGS. 1 and 2.

First, after mixing oxalic acid dihydrate, a boron compound, a lithium compound, and a solvent, the temperature is raised to react.

The boron compound may use any boron compound for preparing lithium bisoxalate borate (LiBOB), preferably boric acid (H ₃ BO ₃ ), boron oxide (B ₂ O ₃ ) and boric acid ester (B(OR ) ₃ ) (where R is methyl or ethyl) may include one or more selected from the group consisting of, more preferably boric acid (H ₃ BO ₃ ) may be included.

The lithium compound may use any lithium compound for producing lithium bisoxalate borate (LiBOB), preferably lithium hydroxide monohydrate (LiOH H ₂ O), lithium hydroxide (LiOH), lithium carbonate (Li ₂ CO ₃ ), lithium oxalate, and LiOR (where R is methyl or ethyl), and may include at least one selected from the group consisting of, more preferably lithium hydroxide monohydrate (LiOH H ₂ O). can

The solvent is at least one selected from the group consisting of water, propylene carbonate, ethylene carbonate, dimethyl carbonate, ethyl methyl carbonate and diethyl carbonate It may include, preferably at least one selected from the group consisting of water and propylene carbonate.

According to one embodiment of the present invention, the solvent may include water and propylene carbonate.

The amount of the propylene carbonate relative to 100 parts by weight of the water may be 50 to 200 parts by weight.

The reaction formula of lithium bisoxalatoborate prepared according to the method for preparing lithium bisoxalatoborate of the present invention is shown in Scheme 1 below.

[Scheme 1]

After mixing the oxalic acid dihydrate, the boron compound, the lithium compound, and the solvent, the reaction may be performed by raising the temperature to a temperature of 90 to 110 ° C, preferably by raising the temperature to a temperature of 95 to 105 ° C. can

The reaction may be carried out for 0.5 to 5 hours, preferably 0.5 to 2 hours.

In the reaction step, 310 to 315 g of oxalic acid dihydrate, 72 to 77 g of boron compound, preferably boric acid, and a lithium compound, preferably lithium hydroxide monohydrate, are added to the reaction vessel. 58 to 63 g, 444 to 445 g of solvent are added, and the temperature is raised to 100° C., and then reacted for 1 hour.

When the amount of oxalic acid dihydrate is less than 310 g, the yield of the produced lithium bisoxalate borate (LiBOB) is undesirably lowered, and when the amount exceeds 315 g, the yield is not improved any more.

If the boric acid is less than 72 g, the yield of the produced lithium bisoxalate borate (LiBOB) is undesirably lowered, and if it exceeds 77 g, unremoved boric acid remains.

When the amount of lithium hydroxide monohydrate is less than 58 g, the yield of the produced lithium bisoxalate borate (LiBOB) is undesirably lowered, and when the amount exceeds 63 g, the yield is not further improved, which is not preferable.

Next, the water generated in the reaction step is removed by vacuum distillation while bubbling gas to the reaction product.

The gas may be an inert gas or air.

The inert gas may include at least one selected from the group consisting of nitrogen, helium, neon, argon, krypton, xenon, and radon, and may preferably include nitrogen.

When vacuum distillation is performed while bubbling nitrogen, the surface area bonding distance between the solvent and Li of the target compound, lithium bisoxalate borate (LiBOB) is weakened, so that after the reaction, moisture, impurities and various gases coordinating with lithium ions are efficiently removed. to obtain high-purity lithium bisoxalate borate.

The vacuum distillation may be performed at 80 to 100 °C, preferably at 85 to 95 °C.

Referring to FIG. 2, the method for producing the lithium bisoxalate borate includes removing water generated in the reaction step by vacuum distillation while bubbling gas to the reaction product; Thereafter, after cooling the reactant from which the water has been removed, first filtering to remove the first impurities; may be further included.

The cooling temperature may be 15 to 35 °C, preferably 20 to 30 °C.

After cooling the reactant from which the water has been removed, adding propylene carbonate and dimethoxyethane to the reaction product and vacuum concentration may be further included.

The reason for adding propylene carbonate and dimethoxyethane is to dissolve the target compound, LiBOB.

Dimethoxyethane can be completely concentrated through vacuum concentration, which is to remove remaining moisture by azeotropy while concentrating.

The step of adding propylene carbonate and dimethoxyethane and vacuum concentration may be performed before the primary filtration.

The vacuum concentration may be performed at a pressure of 5 torr to 300 torr, preferably at a pressure of 5 torr to 150 torr.

After the vacuum concentration, a step of cooling to 15 to 35° C., preferably 20 to 30° C. may be further included, which may be performed before the primary filtration.

Referring also to FIG. 2 , the method for producing the lithium bisoxalate borate may include cooling the reactant from which the water has been removed, followed by first filtration to remove first impurities; Thereafter, adding dimethoxyethane to the reactant and removing secondary impurities by secondary filtration; may be further included.

The reason for adding the dimethoxyethane is to remove impurities while filtering.

The method may further include vacuum-concentrating the dimethoxyethane after removing the secondary impurities.

The step of vacuum concentrating the dimethoxyethane is a step before crystallization of the target compound, LiBOB.

The step of vacuum concentrating the dimethoxyethane may be performed before introducing the following ethylmethyl carbonate.

The vacuum concentration may be performed at a pressure of 5 torr to 300 torr, preferably at a pressure of 5 torr to 150 torr.

Referring also to FIG. 2, the method for preparing the lithium bisoxalate borate may include adding dimethoxyethane to the reactant and performing secondary filtration to remove secondary impurities; Thereafter, the step of adding ethylmethyl carbonate to the reactant, precipitating it as a solid by tertiary filtration, and vacuum drying; may be further included.

The ethylmethyl carbonate is a solvent necessary for crystallizing the target compound, LiBOB, and the reason why ethylmethyl carbonate is added is to crystallize LiBOB.

The vacuum drying may be performed for 5 to 20 hours, preferably for 10 to 15 hours.

In the method for producing lithium bisoxalate borate (LiBOB) according to the present invention, the method is characterized by producing lithium bisoxalate borate (LiBOB) with a yield of 60 to 80%.

The yield of lithium bisoxalatoborate (LiBOB) according to the present invention is calculated according to Equation 1 below. In Equation 1 below, the unit of final weight is g.

[Equation 1]

Final weight / (number of moles of product × molecular weight of product)

In addition, the present invention provides lithium bisoxalate borate prepared according to the above preparation method.

In addition, the present invention provides an electrolyte for a secondary battery containing the lithium bisoxalate borate.

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

< Example >

Example: Preparation of LiBOB using nitrogen bubbles

Example 1

313 g of oxalic acid dihydrate, 75 g of boric acid, 60 g of lithium hydroxide monohydrate, and 444 g of water (DIW, H ₂ O) as a solvent were added to a 1000 ml four-necked reaction flask equipped with a thermometer, a heating device, a distillation concentrating device, and a nitrogen bubble device. . After slowly raising the temperature to 100 ° C., the mixture was reacted for 1 hour. Water was removed by vacuum distillation at 90° C. while bubbling nitrogen. After slowly cooling to 25°C, 329g of propylene carbonate and 329g of dimethoxyethane were added and stirred. After completely concentrating the dimethoxyethane through vacuum concentration, it was slowly cooled to 25° C. and filtered first to remove first impurities.

The filtrate was put into a 4-neck 1000ml reaction flask and dissolved by adding 682g of dimethoxyethane. Thereafter, secondary impurities were removed by secondary filtration, and the dimethoxyethane was vacuum concentrated to about 1/2. Thereafter, 237 g of ethylmethyl carbonate was added, filtered tertiary to obtain a solid, and vacuum dried to obtain 165 g (yield: 70%) of lithium bisoxalate borate (LiBOB).

Example 2

Lithium bis was prepared in the same manner as in Example 1, except that 296 g of water (H ₂ O) and 148 g of propylene carbonate (PC) were added as solvents instead of 444 g of water (H ₂ O) as the solvent in Example 1. Oxalatoborate (LiBOB) was obtained.

Example 3

Lithium bis was prepared in the same manner as in Example 1, except that 222 g of water (H ₂ O) and 222 g of propylene carbonate (PC) were added as solvents instead of 444 g of water (H ₂ O) as the solvent in Example 1. Oxalatoborate (LiBOB) was obtained.

Example 4

Lithium bis was prepared in the same manner as in Example 1, except that 178 g of water (H ₂ O) and 267 g of propylene carbonate (PC) were added as solvents instead of 444 g of water (H ₂ O) as the solvent in Example 1. Oxalatoborate (LiBOB) was obtained.

Example 5

Lithium bis was prepared in the same manner as in Example 1, except that 148 g of water (H ₂ O) and 296 g of propylene carbonate (PC) were added as solvents instead of 444 g of water (H ₂ O) as the solvent in Example 1. Oxalatoborate (LiBOB) was obtained.

Amount (g) of water (H ₂ O) and propylene carbonate (PC) used in Examples 1 to 5, ratio (w / w) of water (H ₂ O) / propylene carbonate (PC), and prepared lithium bis The amount (g) and yield (%) of oxalatoborate (LiBOB) are shown in Table 1 below.

Whether to use nitrogen bubbles amount of solvent used
(g) Ratio of H ₂ O/PC
(w/w) Amount of LiBOB Manufactured
(g) transference number
(%) H ₂ O PC Example 1 ○ 444 0 100/0 165 70 Example 2 ○ 296 148 100/50 170 72 Example 3 ○ 222 222 100/100 170 72 Example 4 ○ 178 267 100/150 172 73 Example 5 ○ 148 296 100/200 177 75

Comparative Example: Preparation of LiBOB without using nitrogen bubbles

Comparative Example 1

313 g of oxalic acid dihydrate, 75 g of boric acid, 60 g of lithium hydroxide monohydrate, and 444 g of water (DIW, H ₂ O) as a solvent were added to a 1000 ml four-necked reaction flask equipped with a thermometer, a heating device, and a distillation concentration device. After slowly raising the temperature to 100 ° C., the mixture was reacted for 1 hour. Water was removed by vacuum distillation at 90°C. After slowly cooling to 25°C, 329g of propylene carbonate and 329g of dimethoxyethane were added and stirred. After completely concentrating the dimethoxyethane through vacuum concentration, it was slowly cooled to 25° C. and filtered first to remove first impurities.

The filtrate was put into a 4-neck 1000ml reaction flask and dissolved by adding 682g of dimethoxyethane. Thereafter, secondary impurities were removed by secondary filtration, and the dimethoxyethane was vacuum concentrated to about 1/2. Thereafter, 236 g of ethylmethyl carbonate was added, filtered tertiary to obtain a solid, and vacuum dried to obtain lithium bisoxalate borate (LiBOB).

Comparative Example 2

Lithium bis was prepared in the same manner as in Comparative Example 1, except that 296 g of water (H ₂ O) and 148 g of propylene carbonate (PC) were added as solvents instead of 444 g of water (H ₂ O) as the solvent in Comparative Example 1. Oxalatoborate (LiBOB) was obtained.

Comparative Example 3

Lithium bis was prepared in the same manner as in Comparative Example 1, except that 222 g of water (H ₂ O) and 222 g of propylene carbonate (PC) were added as solvents instead of 444 g of water (H ₂ O) as the solvent in Comparative Example 1. Oxalatoborate (LiBOB) was obtained.

Comparative Example 4

Lithium bis was prepared in the same manner as in Comparative Example 1, except that 178 g of water (H ₂ O) and 267 g of propylene carbonate (PC) were added as solvents instead of 444 g of water (H ₂ O) as the solvent in Comparative Example 1. Oxalatoborate (LiBOB) was obtained.

Comparative Example 5

Lithium bis was prepared in the same manner as in Comparative Example 1, except that 148 g of water (H ₂ O) and 296 g of propylene carbonate (PC) were added as solvents instead of 444 g of water (H ₂ O) as the solvent in Comparative Example 1. Oxalatoborate (LiBOB) was obtained.

Amount (g) of water (H ₂ O) and propylene carbonate (PC) used in Comparative Examples 1 to 5, ratio (w / w) of water (H ₂ O) / propylene carbonate (PC), and prepared lithium bis The amount (g) and yield (%) of oxalate borate (LiBOB) are shown in Table 2 below.

Whether to use nitrogen bubbles amount of solvent used
(g) Ratio of H ₂ O/PC
(w/w) Amount of LiBOB Manufactured
(g) transference number
(%) H ₂ O PC Comparative Example 1 X 444 0 100/0 142 60 Comparative Example 2 X 296 148 100/50 144 61 Comparative Example 3 X 222 222 100/100 146 62 Comparative Example 4 X 178 267 100/150 146 62 Comparative Example 5 X 148 296 100/200 150 65

<Experimental Example>

Experimental Example 1: Comparison of purity and moisture (ppm) of prepared LiBOB

LiBOBs prepared according to Examples 1 to 5 and Comparative Examples 1 to 5 Purity and moisture (ppm) are shown in Tables 3 and 4 below, respectively.

Whether to use nitrogen bubbles Ratio of H ₂ O/PC
(w/w) transference number
(%) water moisture
(ppm) Example 1 ○ 100/0 70 99.9 93 Example 2 ○ 100/50 72 99.9 93 Example 3 ○ 100/100 72 99.9 92 Example 4 ○ 100/150 73 99.9 92 Example 5 ○ 100/200 75 99.9 92

Whether to use nitrogen bubbles Ratio of H ₂ O/PC
(w/w) transference number
(%) water moisture
(ppm) Comparative Example 1 X 100/0 60 99.6 150 Comparative Example 2 X 100/50 61 99.7 142 Comparative Example 3 X 100/100 62 99.7 140 Comparative Example 4 X 100/150 62 99.8 130 Comparative Example 5 X 100/200 65 99.8 130

Referring to Tables 3 and 4, it was possible to confirm differences in purity, yield, and moisture, which are the quality of the target compound (LiBOB), by comparing whether or not nitrogen bubbles were used. Comparative Examples 1 to 5 without using nitrogen bubbles had yields of 60-65%, but Examples 1 to 5 using nitrogen bubbles had yields of 70-75%. By using nitrogen bubbles, the yield of the target compound (LiBOB) was I could see it getting higher.

In Comparative Examples 1 to 5 without using nitrogen bubbles, the moisture content is 130-150 ppm, but in Examples 1 to 5 using nitrogen bubbles, the moisture content is 100 ppm or less, and by using nitrogen bubbles, moisture is efficiently removed to produce high-quality LiBOB. can be manufactured

In the above, the present invention has been described in detail with preferred embodiments with reference to the drawings, but the scope of the technical idea of the present invention is not limited to these drawings and embodiments. Therefore, various modifications or equivalent ranges of embodiments may exist within the scope of the technical idea of the present invention. Therefore, the scope of the technical idea according to the present invention should be interpreted by the claims, and the technical idea within the equivalent or equivalent range should be construed as belonging to the scope of the present invention.

Claims (15)

mixing oxalic acid dihydrate, a boron compound, a lithium compound, and a solvent, and then reacting by raising the temperature;
vacuum distillation while bubbling gas to the reacted reactants to remove generated water;
After cooling the reactant from which the water was removed, first filtering to remove first impurities;
Injecting dimethoxyethane into the reaction product from which primary impurities were removed by primary filtration and secondary filtration to remove secondary impurities; and
A method for producing lithium bisoxalate borate, comprising the steps of adding ethylmethyl carbonate to the reactant from which secondary impurities were removed by secondary filtration, precipitating as a solid by tertiary filtration, and vacuum drying. According to claim 1,
The method for producing lithium bisoxalatoborate, characterized in that the gas is an inert gas or air. According to claim 2,
The method for producing lithium bisoxalate borate, characterized in that the inert gas includes at least one selected from the group consisting of nitrogen, helium, neon, argon, krypton, xenon and radon. According to claim 1,
The boron compound includes at least one selected from the group consisting of boric acid (H ₃ BO ₃ ), boron oxide (B ₂ O ₃ ), and boric acid ester (B(OR) ₃ ) (where R is methyl or ethyl). Method for producing lithium bisoxalate borate, characterized in that. According to claim 1,
The lithium compound is selected from the group consisting of lithium hydroxide monohydrate (LiOH H ₂ O), lithium hydroxide (LiOH), lithium carbonate (Li ₂ CO ₃ ), lithium oxalate and LiOR (where R is methyl or ethyl) A method for producing lithium bisoxalate borate, characterized in that it comprises at least one. According to claim 1,
The solvent is at least one selected from the group consisting of water, propylene carbonate, ethylene carbonate, dimethyl carbonate, ethyl methyl carbonate and diethyl carbonate Method for producing lithium bisoxalate borate, characterized in that it comprises a. According to claim 6,
The method for producing lithium bisoxalate borate, characterized in that the solvent comprises water and propylene carbonate. According to claim 7,
Method for producing lithium bisoxalate borate, characterized in that the content of the propylene carbonate is 50 to 200 parts by weight relative to 100 parts by weight of the water. delete According to claim 1,
After cooling the reactant from which the water was removed, adding propylene carbonate and dimethoxyethane and concentrating in vacuum. delete According to claim 1,
Method for producing lithium bisoxalatoborate, characterized in that it further comprises; after removing the secondary impurities, vacuum-concentrating the dimethoxyethane. delete delete delete

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