JPS5935012A - Purification of graphite fluoride - Google Patents

Abstract

PURPOSE:To prepare purified graphite fluoride useful as an active substance of cell, etc. free from a bad smell and corrosive properties, by treating graphite fluoride with an ammonia gas so that remaining unliked fluorine is removed. CONSTITUTION:The crude graphite fluoride 3 is packed on the porous plate 2 of the purification column 1, NH3 introduced from the pipe 5 is brought into contact with it for about 5min-48hr while it is heated by the heater 4 at room temperature - about 200 deg.C, unreacted NH3 and the reaction product are discharged from the pipe 6, to give graphite fluoride containing no unlinked fluorine.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention uses graphite fluoride (Graphite Fluori
This article is about the purification method of GF (hereinafter abbreviated as GF).
The purpose is to remove non-bonded fluorine present in F.

GF is a solid powder obtained by reacting carbon or graphite with fluorine, and is known to be represented by (OF)n or (02F)n, and has unique lubricity and para-oil properties. Because of its excellent resistance to wear and tear, it is used as a solid lubricant, wetting-proofing agent, antifouling agent, water blistering oil, etc. It is also used as a battery active material, and has good shelf life. , is well known to provide high energy density primary cells.

However, GF contains a small number of fluorine atoms that are not completely covalently bonded to carbon atoms, which causes problems in terms of odor and hygiene during handling, and may also cause problems in terms of physical properties depending on the application. For example, when IJF is used as a battery active material, the current collector of the positive electrode may be oxidized during storage of the battery, or the solvent of the non-aqueous electrolyte may be decomposed and deteriorated, or the lithium surface of the negative electrode may be corroded. It has the effect of

This fluorine is adsorbed in OF interlayers and crystal defects, and its desorption rate is very slow, so it cannot be easily removed. The amount of unbonded fluorine varies depending on the type of raw material and the reaction rate, and it is larger for graphitic raw materials with a lower reaction rate.

A method for removing such unbound fluorine is to add alcohol to OF, then add a strong alkaline aqueous solution or a strong acid aqueous solution and boil it (Japanese Patent Publication No. 56-36790). The process is very complicated as it must be separated and dried. Furthermore, when used as a battery active material, the storage life of the battery was not necessarily sufficient.

For these reasons, an efficient and simple method for removing non-bonded fluorine without deteriorating the performance of GF is desired.

Therefore, the present inventors have worked hard to find an efficient and simple method for removing non-bonded fluorine from GF (as a result of repeated research on GFf
It was discovered that non-bonded fluorine contained in GF can be efficiently removed by an extremely simple method of treatment using ammonia gas, and the present invention was completed.

The GF used in this book 56 is (OF)n.

(02F)r+ or a mixture C thereof may be present, or it may contain unreacted graphite during the reaction.

In the present invention, in addition to using ammonia gas alone, other N2. It can also be used in combination with a gas inert to GF and ammonia, such as Ar, A, ir, and He. The treatment temperature may be any temperature as long as the thermal decomposition of GF does not occur, and is preferably room temperature to 200°C from the viewpoint of ease of treatment.

The longer the treatment time, the less unbound fluorine in the CF, but the removal rate gradually slows down, so 5 minutes to 48 hours is preferable as long as the purification is within a range that poses no practical problems.

As the processing device, any device may be used as long as the ammonia gas and all the GFs come into contact with each other efficiently.

EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples, but the scope of the present invention is not limited to the Examples.

In addition, the non-bonded fluorine content in CF was determined by the following method. 50n volumetric flask (made of brown crow)
Add 500 mg of G'F' and saturated ethanol solution for 50. 1 and mix well. 48 in the darkroom
After standing for hr, liberated iodine was titrated with 1/250 N sodium thiosulfate, and fluorine capable of oxidizing iodine ions was determined as unbound fluorine.

Example 1 A schematic diagram of the apparatus used for the treatment is shown in FIG.

1 is a 50φ x 300H bolt purification tower made of 5U8304, 2 is a porous plate, 3 is a GF, 4 is a heating heater, 5 is an ammonia gas introduction pipe, and 6 is an exhaust pipe for unreacted ammonia gas and reaction products. show.

The GF used was manufactured from artificial graphite and was a (02F) type GF containing fluorine with a weight of 51.6w and 70cm. The amount of unbonded fluorine in this product was 0.30wt6 (J
After installing Floog in the apparatus, gas was introduced into the lower part at a rate of 10,000/min, and the treatment was carried out at room temperature for 5 hours. Thereafter, it was dried at 150°C for 5 hours. The non-bonded fluorine content of this product was 0.07 Wll-h.

Example 2 After 48 hours of treatment at room temperature in the same manner as in Example 1, 1
It was dried at 50°C for 5 hours.

Unbound fluorine t was 0.04 wt%.

Example 3 Ihr treatment was carried out at 130° C. in the same manner as in Example 1. However, drying was not performed. Unbound fluoric acid is 0.08W
It was 't;

Example 4 Example! It was treated in the same manner as above at 180°C for 5 hours.

However, drying was not performed. Unbound fluoric acid is 0,
It was 0.02 wt%.

Example 5 Processing device K1 The method was the same as in Example I, with 62.7 wt% of fluorine-containing needles made from petroleum coke as GF (
CF) n-type GF"i was used. The unbound fluoric acid content of this was 0.04 W'l;%.

The N1h treatment was performed at room temperature for 5 hours and dried at 150°C for 5 hours.

The amount of unbound fluorine is 0, Ofvi l; %/ζ.

Example 6 The processing equipment and method were the same as in Example 1, and the GF was (C2) with a fluorine content of 48.6W produced from natural graphite.
F') niGF containing a small amount of unreacted graphite was used. The amount of non-bonded fluorine in this product is 0.73wt%
Met.

The NH treatment was performed at room temperature for 48 hours, and then dried at 150° C. for 5 hours.

The amount of unbound fluorine was 0.06 wt%.

Comparative Example 1 Using the same GF as in Example 1, in vacuum (3 Torr), 1
Drying treatment was carried out at 20° C. for 24 hours. As a result, the amount of unbonded fluorine was 0.30 wt% in the untreated state, but 0.2
The amount was only 9 wt%, and no effect was observed at all.

Example 7, Comparative Example 2 Example! (a2ir)n (unbound fluoride,
0.07 wt%) [Example 7], used in Example 1 (0
2F) Add 22 methanol to type GF111/, and then add 22 6N#L acid! was added, washed by boiling for about 1 hour, then washed with gradients until no chlorine ions were detected, dehydrated, and dried to obtain a solution with zero unbound fluorine content.
．． 08wt% (02F)n (Comparative Example 2), and the untreated (OzF')n used in Example I (unbonded fluorine amount 0).
, 30 wt%) [Reference Example], the battery characteristics were measured by the following method, both initially and after storage at 45° C. for 6 months and 2 years.

Using expanded graphite (manufactured by Toyo Tanso Co., Ltd.) as a conductive agent and a binder, it was mixed with (02F)n at a weight ratio of I:1, and a
It was compressed for 1 minute at a pressure of KP/cy/I and formed into a pellet with a diameter of 1Qwa, which was used as a positive electrode. The negative electrode was cut out from a lithium block and used as it was. Lithium perchlorate (LIOQO4) as electrolyte
f I moQ/1. A dissolved flopylene carbonate solution was used. These 't4i and pond-forming elements were placed in a Tenron container, and all experiments were conducted in a dry box with a 30C argon atmosphere. fJf and interpolar distance were 10jI#.
The discharge characteristics were measured under a constant resistance load of 1 in 20 l. Table 1 shows the discharge duration resulting in a final voltage of 2.5 V for each.

Table 1 As is clear from this table, according to the present invention, the preservation characteristics are significantly improved compared to the untreated case, and the preservation characteristics are superior even when compared with conventional treatment methods. .

Figure 2 shows the release characteristics of each side after one year of storage. In the figure (gradient is 7% for Example), (B) indicates Comparative Example 2, and (0) indicates Reference Example.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an example of an apparatus for implementing the present invention. FIG. 2 is a graph showing the battery characteristics of GF treated according to the present invention, conventionally treated GF, and untreated GF.

Claims (1)

[Claims] A method for purifying fluorinated graphite characterized by treating fluorinated graphite with ammonia gas