JP3527518B2 - Manufacturing method of positive electrode for non-aqueous electrolyte lithium secondary battery - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [0001] The present invention relates to a nonaqueous electrolyte lithium secondary battery.
The following relates to batteries. [0002] 2. Description of the Related Art Lithium or a lithium compound is used as a negative electrode.
Non-aqueous electrolyte rechargeable batteries have high voltage and high energy density
Many studies have been conducted. Until now, positive electrode active materials for non-aqueous electrolyte secondary batteries
As LiCoO_Two, LiMn_TwoO _Four, LiFeO_Two, L
iNiO_Two, V_TwoO_Five, Cr_TwoO_Five, MnO_Two, TiS_Two, M
oS_TwoOxides and chalcogen compounds of transition metals such as
Are proposed, which are layered or tunneled
With a crystal structure that allows lithium ions to enter and exit
One. In particular, LiCoO_TwoAnd LiNiO_Two, LiMn_TwoO_FourIs
As a positive active material for 4V class non-aqueous electrolyte lithium secondary batteries
Is attracting attention. However, among these, the most promising in terms of characteristics
LiCoO as the positive electrode active material_TwoIs a source of expensive cobalt
And costly. Furthermore, the raw materials
There are concerns about supply, and supply is not
It is also possible that the price and price will rise. Also, LiM
n_TwoO_FourAnd LiNiO_TwoIs characteristically LiCoO_TwoCompare with
Is slightly inferior, but the manga
Supply of nickel and nickel compounds at very low cost
There is no need to worry about cost and raw material supply. further,
LiNiO_TwoIs LiCoO_TwoHas the same composition and structure as
High capacity, high voltage positive electrode active material for lithium secondary batteries
It is expected material. [0005] SUMMARY OF THE INVENTION However, LiN
iO_TwoWhen using as a positive electrode active material, its synthesis is easy
is not. Journal of American Chemical Sosa
Et., 76, 1499 (1954).
As described above, anhydrous lithium hydroxide and metallic nickel
Although it can be synthesized by reacting under an elemental atmosphere,
Material properties are inadequate. Also chemis
Tree Express, Volume 6, Issue 3, Item 161 (199
As described in 1), nickel hydroxide and nitric acid
Reaction in an aqueous solution system and 800
Obtaining an active material with good properties by firing at ℃
Although there are reports that they can be produced,
Would be complicated. And in this method
The reproducibility is poor, and the characteristics vary widely.
Therefore, a simpler synthesis method than the above method was adopted.
By heating and firing a mixture of a Li source and a Ni source.
A direct reaction is possible. In this case, the source of Li
Titanium, lithium hydroxide and lithium carbonate are Ni sources
Consider nickel nitrate, nickel hydroxide and nickel carbonate.
available. Firing at a temperature in the range of 600 ° C to 850 ° C
In any case, any combination of Li source and Ni source
NiO_TwoIs possible, but depending on the starting materials,
Crystal phase with inferior properties may be mixed.
You. Due to the formation of a crystal phase with inferior characteristics, the charge / discharge capacity
Is significantly reduced. Therefore, Lithium having excellent properties
In order to obtain a positive electrode for a secondary battery,
It is necessary to use a material in which a crystal phase is less mixed. The present invention solves such a problem.
Therefore, a positive electrode for lithium secondary batteries with excellent characteristics
To offer. [0007] SUMMARY OF THE INVENTION Reversible occlusion of lithium.
Positive electrode capable of release and lithium or lithium
From a negative electrode containing a compound mainly composed of
Positive electrode active material used in non-aqueous electrolyte lithium secondary batteries
A certain LiNiO_TwoOf lithium nitrate and carbonic acid
With nickel1: 1 molar ratioAfter mixing, 600 ~
By firing at 850 ° C., the Li by X-ray diffraction
NiO_Two003 reflection peak intensity and 104 reflection
Intensity ratio to peak intensity (003/104) 1.20 or less
Characterized by the aboveIs the thing. [0008] [Function] As one of composite oxides of nickel and lithium
LiNiO_TwoThere is a compound represented by the following composition: this
LiNiO_TwoIs LiCoO having a similar composition_TwoSame as the six directions
For non-aqueous electrolyte lithium secondary batteries
High potential for excellent properties as positive electrode active material
Is done. However, it is not easy to synthesize
It is very difficult to obtain sex. [0009] First, as a starting material, Ni source is added to Ni source.
Nickel acid, nickel hydroxide and nickel carbonate are
Lithium nitrate, lithium hydroxide and lithium carbonate
As a result of studying the sintering conditions used, it was found that
Baking in the temperature range of 0 ° C forms hexagonal crystals with excellent properties.
It was found that the synthesis of the crystal phase was possible. Below 600 ° C
The reaction does not proceed sufficiently at a temperature of 850 ° C or higher.
Crystal phase with inferior properties having rock salt type structure
Will be formed. However, firing at temperatures below 850 ° C
Even if it is formed, there is a large difference in capacity due to the difference in starting materials.
It was observed. Among the combinations of starting materials mentioned above,
And / or nickel hydroxide or nickel carbonate
In the case of the combination with, a large capacity was obtained. At this time, each sample by X-ray diffraction measurement
Investigation of the diffraction pattern of
, The intensity ratio of each peak is different.
The peak intensity changed greatly. 003 for each sample
Small change in intensity to quantitatively compare the peak intensity of the surface
Of the intensity ratio (003/104) with the peak of
As a result of calculation, 003/1 was obtained for a sample having a large capacity.
04 has a large peak intensity ratio,
The peak intensity ratio was also smaller in the sample. Especially 003 /
104 has excellent properties in samples of 1.20 or more
Was. In the rock salt type crystal structure, the reflection corresponding to 003 is
Because the peak intensity of 003 becomes smaller,
The mixing ratio of salt-type crystal phase is large and the capacity is small.
It is thought that there is. Therefore, the value of 003/104 is large.
Preferably, LiNiO of 1.20 or more_TwoUsing
Positive electrode for lithium secondary battery with excellent characteristics
Can be obtained. [0011] DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to embodiments.
However, the present invention is not limited to these examples. (Example 1) In this example, the starting material
LiNO as lithium source_Three(Lithium nitrate), Li (O
H)_Two(Lithium hydroxide), Li_TwoCO_Three(Lithium carbonate
Ni) for the nickel source_Three(Nickel nitrate), Ni
(OH)_Two(Nickel hydroxide), NiCO_Three(Nicke carbonate
) Is used as the positive electrode active material.
The case where lithium is used as the negative electrode active material will be described.
You. First, the respective combinations of the Li source and the Ni source
About 1: 1 molar ratio of lithium and nickel
Weigh in, add a small amount of water as a dispersion medium and mix thoroughly.
After drying, dry and bake at 650 ° C for 12 hours in air.
A color fired product was obtained. X-ray powder analysis of the obtained fired product
A folding measurement was performed to obtain each X-ray diffraction pattern. Fired
Lithium nitrate and carbonic acid as typical X-ray diffraction patterns
FIG. 2 shows a pattern when nickel is used as a starting material. Next, each fired product is used as an active material to form a positive electrode.
Produced. The preparation of the positive electrode begins with the active material and the conductive agent.
Cetylene black and polyfluoroethylene as binder
Mix the resins in a weight ratio of 7: 2: 1 and mix thoroughly
The dried product was used as a positive electrode mixture. This positive electrode mixture 0.15
g to 2 ton / cm^TwoInto a 17.5mm diameter pellet
Pressure molding was performed to obtain a positive electrode. Using the electrodes manufactured as described above,
FIG. 1 is a cross-sectional view of the battery. Place positive electrode 1 in case 2
And a porous polypropylene as a separator 3 on the positive electrode 1.
The ren film was placed. 0.8 m thick as the negative electrode 4
m, 17.5mm diameter lithium plate made of polypropylene
Pressure bonding to sealing plate 7 with gasket 5 and negative electrode current collector 6
did. 1 mol / l lithium perchlorate as non-aqueous electrolyte
Propylene carbonate in which chromium was dissolved. this
On the separator 3, the positive electrode 1 and the negative electrode 4,
The battery was sealed. As described above, for each combination
A battery was prepared and its initial discharge capacity was examined. The charging and discharging conditions are as follows.
The voltage range was 3.0 V to 4.3 V. Table 1
The initial discharge capacity of each battery and 003/104 are shown.
You. [0018] [Table 1] As shown in Table 1, the value of 003/104 is
1.20 or more lithium nitrate and nickel carbonate, nitric acid
In the case of a combination of lithium and nickel hydroxide starting materials
It turns out that a large capacity can be obtained. Among the,
The highest capacity is obtained when combining lithium nitrate and nickel carbonate.
The value of 003/104 is also 1.32, the largest value
It has become. Conversely, if the value of 003/104 is small,
In particular, the capacity is small when it is less than 1.00,
Unsatisfactory for positive electrode active material with initial capacity of 100 mAh or less
Characteristics. As shown above, the X-ray diffraction method
The ratio of the peak intensity ratio between the reflection on the 003 surface and the reflection on the 104 surface
The value of 003/104 is 1.20 or more.
LiNiO_TwoBy using as a positive electrode active material
Easy to use as a positive electrode for lithium secondary batteries with excellent characteristics
Can be obtained. [0021] As will be apparent from the above description of the embodiments.
Positive electrode capable of reversibly inserting and extracting lithium
And lithium or lithium-based compounds
A non-aqueous electrolyte comprising a negative electrode and a non-aqueous electrolyte
Positive electrode used for secondary battery, 003 surface by X-ray diffraction method
Of the peak intensity of the reflection of the surface and the peak intensity of the reflection of the 104 surface
LiNi with a degree ratio (003/104) of 1.20 or more
O_TwoNon-aqueous electrolyte lithium secondary battery characterized by containing
A positive electrode for a pond can be easily obtained.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal sectional view of a battery according to an embodiment of the present invention. FIG. 2 is a view showing an X-ray diffraction pattern of LiNiO ₂ . Gasket 6 Negative electrode current collector 7 Sealing plate 8 Positive electrode current collector

   ────────────────────────────────────────────────── ─── Continuation of front page    (72) Inventor Shuji Ito               1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric               Kiki Sangyo Co., Ltd. (72) Inventor Yasuhiko Mito               1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric               Kiki Sangyo Co., Ltd. (72) Inventor Yoshinori Toyoguchi               1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric               Kiki Sangyo Co., Ltd.                (56) References JP-A-6-111822 (JP, A)                 Tsutomu OHZUKU, et                 al. , "Synthesis an               d Characterization                 of LiNiO ▼ Bottom 2 ▲ (R3m)               for Rechangeable N               onagueous Cells ", C               hemistry Express (J               apan), Kinki Chemical               al Society, 1991, Vol.               6, No. 3, p161-164

Claims (1)

(57) [Claim 1] A positive electrode capable of inserting and extracting lithium reversibly, a negative electrode containing lithium or a compound mainly composed of lithium, and a nonaqueous electrolyte lithium comprising a nonaqueous electrolyte LiNiO, a positive electrode active material used for secondary batteries
Manufacturing method ₂ in which lithium nitrate and nickel carbonate are modeled.
After mixing at a mixing ratio of 1: 1 and firing at 600 to 850 ° C., the LiNiO ₂
A method for producing a positive electrode for a non-aqueous electrolyte lithium secondary battery, wherein the intensity ratio (003/104) between the reflection peak intensity on the three surfaces and the reflection peak intensity on the 104 surface is 1.20 or more.