JP2000067924A - Lithium ion battery having adjusted electrode interface and electrochemical process - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent gas generation in a battery due to the decomposition of a solvent by setting, in a certain range, the value of a relative thickness index relating to carbon and lithium in a discharge condition after performing charge and discharge of one or more cycles and the value of a relative lithium ion containing index regarding a stationary layer formed on the surface of a carbonaceous electrode. SOLUTION: The value of a relative thickness index equal to A[Cls(2)]/A[Cls(1)] is set around 10-90, and the value of a relative lithium ion containing index equal to A[Lils]/A[Cls(2)] is set around 0.1-0.7, where A[Cls(1)] represents a peak area of the ls level of carbon of which peak tops measured by an X-ray photo-electron spectroscopy reside in the range of 284.4-284.8 eV, A[Cls(2)] represents the entire peak area of the ls level of carbon measured by the X-ray photo-electron spectroscopy, and A[Lils] represents the entire peak area of the ls level of lithium measured by the X-ray photo-electron spectroscopy.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

FIELD OF THE INVENTION The present invention relates to a lithium ion battery having a tuned electrode interface and an electrochemical process. More specifically, the present invention prevents the generation of gas in the battery due to the decomposition of the solvent used in combination with the electrolyte, and the additive does not substantially generate gas in the decomposition of the additive itself during cycling and storage of the battery. And an electrolytic process having the same.

[0002]

2. Description of the Related Art Lithium ion batteries, such as lithium ion secondary batteries, have been known in the art for several years. Further, lithium batteries using a carbon electrode and a liquid, gel, polymer or plastic electrolyte are also well known.

[0003] Although a variety of such electrolytes have been utilized, the use of commercially available solvents in the electrolytes has led to the recognition of several problems associated with those solvents during battery cycling and storage. Became. In fact, two undesirable reactions occur when the solvent decomposes. Specifically, during the initial charging of the battery, the solvent reacts with the electrode interface, where a passivation layer is formed. As a result, the initial charge and discharge of the battery (cyc
le coulomic) efficiency is greatly reduced. Second
First, the solvent in the electrolyte continues to decompose when the battery is first subjected to a charge / discharge cycle, and then when the charge / discharge cycle is continued and when the battery is stored. As a result, gas is generated by the decomposition of the solvent, and the pressure inside the battery increases.

[0004] In order to solve the above problems, in the prior art, a method of reacting with the electrode surface before reacting with the solvent and utilizing an additive added to the solvent / electrolyte has been attempted. As a result, this additive forms a passivation layer to prevent decomposition of the solvent.

[0005] In such prior art batteries, attention has been paid to the decomposition of the solvent.
It has not been solved that the additive is offset by gas generation due to decomposition of the additive itself. Thus, while the use of additives may provide some benefit, the problem of gassing from additives, which opposes the suppression of gassing from solvents, still remains.

[0006]

SUMMARY OF THE INVENTION Gas generation in a battery due to decomposition of a solvent used in combination with an electrolyte is prevented, and substantially no gas is generated during decomposition of the additive itself during cycling and storage of the battery. It is to provide a lithium ion battery and an electrolytic process with additives.

[0007]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to achieve the above object, and as a result, the passive layer has been measured by X-ray photoelectron spectroscopy at least in the discharge state after the first cycle of the battery. It has been found that the above object can be achieved by defining the relationship between the peak areas of carbon and lithium.

The present invention has been completed based on the above findings, and a first gist of the present invention is that a first electrode and a second electrode, at least one of which is a carbonaceous electrode, an electrolyte, A lithium ion battery comprising a passivation layer formed on a surface, wherein the passivation layer contains at least carbon, lithium, an additive and / or a reaction product of the carbonaceous electrode and the additive, In addition, the relative thickness index related to carbon and lithium measured by X-ray photoelectron spectroscopy in a discharge state after one cycle or more of charge and discharge is about 10 to 90, which is represented by the following formula (I). And a relative lithium ion content index represented by the following formula (II) is about 0.1 to 0.7.

[0009]

(1) Relative thickness index = A [C1s (2)] / A [C1s (1)] (I) Relative lithium ion content index = A [Li1s] / A [C1s (2)] (II) (where A [C1s (1)] represents the peak area of the carbon 1s level having a peak top at 284.4 to 284.8 eV, measured by X-ray photoelectron spectroscopy, and A [C1s
(2)] represents the peak area of all carbon 1s levels measured by X-ray photoelectron spectroscopy, and A [Li1s] represents the peak area of all lithium 1s levels measured by X-ray photoelectron spectroscopy. Represents the peak area. )

In a preferred embodiment of the first aspect, at least one of the additive or the reaction product of the additive comprises:
Gas generation due to decomposition of components in the electrolyte or decomposition of additives or reaction products with the additives in the passive layer is substantially prevented.

In another preferred embodiment of the first aspect,
The passivation layer has a relative thickness index of about 20-80.

In another preferred embodiment of the first aspect,
The passivation layer has a relative thickness index of about 30-70.

In another preferred embodiment of the first aspect,
The passivation layer has a relative lithium ion content index of about 0.15 to
0.6.

In another preferred embodiment of the first aspect,
The passivation layer has a relative lithium ion content index of about 0.2 to
0.5.

A second gist of the present invention is that at least one of a first electrode and a second electrode, each of which is a carbonaceous electrode, an electrolyte containing at least one component, and at least one of an electrode having an electrolyte and a carbonaceous electrode. Associate with one (associa
te) An additive in a lithium ion battery comprising: an additive which satisfies the following conditions (a) and (b):

(A) charging a lithium ion battery, and forming a passivation layer on the carbonaceous electrode surface by a chemical reaction between the carbonaceous electrode surface and an additive; (b)
The passivation layer contains at least carbon, lithium, an additive, and / or a reaction product of the carbonaceous electrode and the additive, and (c) performs at least one cycle of charge / discharge in the passivation layer. The relative thickness index represented by the following formula (I) related to carbon and lithium measured by X-ray photoelectron spectroscopy in the discharged state after the discharge is about 10 to 10:
90 and a relative lithium ion content index represented by the following formula (II) is about 0.1 to 0.7.

[0017]

## EQU4 ## Relative thickness index = A [C1s (2)] / A [C1s (1)] (I) Relative lithium ion content index = A [Li1s] / A [C1s (2)] (II) (where A [C1s (1)] represents the peak area of the carbon 1s level where the peak is present at 284.4 to 284.8 eV, as measured by X-ray photoelectron spectroscopy, and A [C1s
(2)] represents the peak area of all carbon 1s levels measured by X-ray photoelectron spectroscopy, and A [Li1s] represents the peak area of all lithium 1s levels measured by X-ray photoelectron spectroscopy. Represents the peak area. )

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. Some aspects disclosed herein are disclosures of the basic principles of the invention and do not limit the invention to this disclosure, as the present invention is capable of many different embodiments.

FIG. 1 is a schematic view of a lithium ion battery 10 according to the present invention before application of electric charge. The lithium ion battery 10 includes a first electrode 12, a second electrode 14, and an electrolyte 16, and the first electrode 12 has a carbonaceous surface 24. The electrolyte 16 contains a solvent 18 or a solvent mixture, a lithium salt (not shown), and an additive 22. Prior to the application of the charge, the additive 22 is shown as being associated with the electrolyte 16, but it is also conceivable that the additive 22 is initially associated with either or both the first electrode 12, the second electrode 14, or both. .

In addition, additive 22 is described in the following experiments in two special ring-opened spiro-ketones (ring ops).
Compounds having similar functional groups, including ring-opened spiro or cycloorganic compounds, are exemplified as compounds consisting of an enzymatic spiro-ketone), especially 1) reacting with the carbonaceous electrode prior to the solvent in the electrolyte. 2) forming a passivation layer having a relative thickness index and a relative lithium ion content index in a specific range described below on the carbonaceous surface; and 3) as a result, a solvent having a gas generating ability in the electrolyte. Are also conceivable, which substantially prevent the gas from coming into contact with the carbonaceous surface and 4) substantially prevent gas evolution within the battery 10 due to decomposition during charge and discharge or storage.

It should be noted that the meaning that the additive 22 prevents gas generation does not prevent all gas generation, but does not prevent gas generation in cases where it is beneficial for the present invention to prevent gas generation. The meaning of preventing is understood by those skilled in the art.

As the solvent 18, an organic carbonate solvent such as PC (propylene carbonate), DEC (diethyl carbonate), DMC (dimethyl carbonate) and EC (ethylene carbonate) can be preferably used. Conventionally used solvents or electrolyte systems (such as liquids, polymers, gels and plastics) which are commercially available can be used as well.

As the lithium salt, LiPF ₆ , LiA
sF ₆ , LiClO ₄ or the like can be used.

FIG. 2 shows the lithium ion battery 1 after one or more cycles of charging and discharging following the initial charge application.
FIG. A passivation layer 40 is present on the carbonaceous surface 24 of the first electrode 12. The passivation layer 40 is made of at least one of carbon, lithium and an additive or a reaction product of the additive with the carbonaceous surface of the first electrode 12. Actual composition of passivation layer 40 and additives 22
(FIG. 1) and the interaction between the carbonaceous surface 24 are described in the corresponding U.S. patent application Ser.
0-50379).

FIG. 3 shows a method of manufacturing the lithium ion battery 10 (FIG. 1) and the actual electrochemical process that takes place in the battery during initial charging. These manufacturing methods and electrochemical processes consist of the following steps.

First, an initial battery is manufactured by assembling the first electrode 12, the second electrode 14, and the electrolyte 16. For purposes of the present disclosure, first electrode 12 includes an anode having a carbonaceous surface layer 24, and second electrode 14 includes a cathode. Of course, in the configuration of a secondary battery, the anode and cathode can be interchangeable depending on whether the battery is charging or discharging. As with the electrodes, certain electrolytes are made using conventional techniques. Further, solvent 18 and additive 22 may be initially associated with the electrolyte. However, at least the additives may be selectively or similarly associated with one or both of the electrodes.

After the completion of the battery assembly, initial charging is performed. With this charging, the additive 22 (FIG. 1) reacts with the carbonaceous surface 24 to form a passivation layer 40 (FIG. 2) on the carbonaceous surface 24 of the electrode 12. By the above reaction, the passivation layer 40
Consists of at least carbon, lithium and the additive 22 and / or a reaction product of the carbonaceous electrode 12 and the additive 22. Furthermore, the passivation layer 40 has a relative thickness index (passivation layer 4
0, which is related to the emission of carbon 1s level measured by X-ray photoelectron spectroscopy) is about 10-90, and the relative lithium ion content index (X-ray photoelectron spectroscopy in the passivation layer 40) (Related to the emission of lithium 1s level measured by the method) is about 0.1 to 0.7.

As shown in Table 1 of the following examples, a lithium ion battery having a passivation layer within the ranges of the relative thickness index and relative lithium ion content index described above corresponds to the corresponding US application Ser. No. 021 (Japanese application, Japanese Patent Application No. 10-50379), when no additive was used and / or the relative thickness index and relative lithium ion content index of the passivation layer 40 were determined by the present invention. It shows a substantially higher initial charge / discharge efficiency as compared to a case outside the specified range. For example, if the additive used in the present invention is used in the passivation layer and the relative thickness index is greater than 90 and the relative lithium ion content index is less than 0.1, the decomposition of the electrolyte is prevented even if the decomposition of the electrolyte is prevented. Electric conductivity and electric conductivity are poor. Conversely, when the relative thickness index of the passivation layer is smaller than 10, and the relative lithium ion content index is larger than 0.7, the passivation layer shows high conductivity, but the prevention of decomposition of the electrolyte is extremely insufficient.

[0029]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the following Examples. The following Examples and Comparative Examples were performed to confirm an increase in initial charge / discharge efficiency and a relative thickness index and a relative lithium ion content index of the passivation layer.

Examples 1 to 3 and Comparative Examples 1 and 2 In Examples 1 and 2 and Comparative Example 1, an electrode (anode) having a carbon surface was evaluated using a three-electrode cell.
The electrodes were cut into 2 × 2 cm ² strips and served as working electrodes. Lithium metal was also cut into 2 × 2 cm ² strips and served as a counter electrode. 0.5 × 0.5c lithium electrode
m ² strips were sandwiched between the working and counter electrodes. Next, the electrode group was separated by glass fiber paper and immersed in an electrolyte solution.

In Examples 1 and 2 and Comparative Example 1, the additives were combined with an electrolyte solution. The electrolyte additive was 5.0 grams of 1,6-dioxaspiro [4,4] nonane-
2,7-dione (hereinafter 1,6 spiro) or 1,4-
Dioxaspiro [4,5] decan-2-one (hereinafter referred to as
1,4 spiro) was prepared by dissolving either 95.0 grams of propylene carbonate or a mixture of propylene carbonate and ethylene carbonate (1: 1 by weight). The solution was then dried on a molecular sieve 4A electronic sieve for 3 days and the water content was less than 20 ppm as determined by conventional Karl-Fischer analysis.
To the solution was dissolved LiAsF ₆ to a concentration of 1M is obtained. The electrolyte solution was further dried using molecular sieves until the desired water content of 20 ppm was obtained, which was also confirmed by Karl-Fischer analysis.

In Examples 1 and 2 and Comparative Example 1, graphite carbon electrodes were produced by the following method. First, 4.9 grams of graphite powder (LONZA KS-6 from Lonza) was combined with 5.0 grams (by weight) of 2% PVdF / NMP (p).
olyvinylideneFluoride / N-m
(ethylpyrrolidone) solution.
The mixture of graphite was milled using a ball mill for about 12 hours to produce a paste. Next, the obtained paste was coated on an undercoated copper foil. Then the solvent NM
P was removed at 80 ° C. under vacuum for about 12 hours.

In Examples 1 and 2 and Comparative Example 1, KS
6 (commercially available carbon material, manufactured by TIMICAL CO., Switzerland) and a carbonaceous material consisting of 2% by weight of PVdF binder. In Example 1 and Comparative Example 1, P
A lithium salt (1M) electrolyte having a C: EC ratio of 1: 1 was used, while in Example 2, a lithium salt (1M) electrolyte without EC was used. In Examples 1 and 2,
The additive of the present invention was used, but in Comparative Example 1, no additive was used as a comparative battery or a prior art example.

In Example 3 and Comparative Example 2, 90% by weight of SFG15 (commercially available carbonaceous material, TI
MICAL CO. (Switzerland), 10% by weight of a PVdF binder was added, and a slurry slurried with an NMP solvent was applied to a copper foil and dried at 120 ° C. for 10 minutes. As the electrolyte, a general lithium salt / PC electrolyte was used. In Example 3, the additive of the present invention was used. In Comparative Example 2, a conventional additive was used for comparison.

In Example 3 and Comparative Example 2, an electrode having a carbon surface was evaluated using a coin-type cell. The electrode was cut into a 13φ disk shape to serve as a working electrode, and a 15φ disk-shaped lithium metal foil was used as a counter electrode. The working electrode was placed on the positive electrode can side, a polyethylene porous membrane separator (25 μm, R-φ) was laid thereon, a counter electrode was overlaid thereon, and finally the negative electrode can was swaged. A gasket made of polypropylene was inserted between the positive electrode can and the negative electrode can to secure insulation.

The determination of the initial charge / discharge efficiency is well known in the prior art and corresponds to US application Ser.
12,021 (Japanese application, Japanese Patent Application No. 10-50379)
), The following describes an experimental method for data that is not compensated by the measurement of X-ray photoelectron spectroscopy, which is a known technique.

In Examples 1 and 2 and Comparative Example 1, each of the lithium ion batteries was charged and discharged for one cycle, and then the carbonaceous electrodes were evaluated by X-ray photoelectron spectroscopy. On the other hand, in Example 3 and Comparative Example 2, after performing three cycles of charging and discharging of each lithium ion battery,
The carbonaceous electrode was evaluated. In Examples 1 and 2 and Comparative Example, charging was performed at a constant current (0.06 mA / cm ^2).
And discharge at a constant current (0.06 mA).
/ Cm ^{2 up} to 25 V). In Example 3 and Comparative Example 2, the charging was performed at a constant current and a constant voltage (0.06
Constant current charging to 5 mV at mA / cm ² and then 0.0
04mA / cm performed in ² Madejo voltage charge), was discharged at a constant current discharge (up to 15V at 0.06 mA / cm ^2).

After performing the above charge / discharge cycle, the battery was disassembled and the carbonaceous electrode was removed. The removed electrode is DME (1,2-dimethoxyethane) for about 10 minutes.
And further dried in vacuum at 40 ° C. for 1 hour.

X-ray photoelectron spectroscopy of the dried electrode was performed to determine the strength of carbon and lithium in the passivation layer formed. Specifically, as an X-ray photoelectron spectroscopy device, PHYSICAL ELECTRONICS
CO. A device consisting of a company ESCA-5500 system was used. Table 1 shows the measurement conditions using the above apparatus.

[0040]

[Table 1] X-ray used: Monochromatic Al Kα ray X-ray acceleration voltage, current: 14 kV, 10.7 mA Electron extraction angle: 65 ° with respect to the sample surface Field of view of electromagnetic focusing lens: 0.8 mm diameter circle Transmission energy : 29.35 eV Measurement data step: 0.125 eV / step Measurement resolution: Under the above measurement conditions, the half width (FWHM) of Ag 3d5 / 2 is 0.75 eV.

All operations were performed under a purified nitrogen atmosphere. Each sample / test electrode was held between the sample holder and the Mo-seat cover. The Mo-seat cover had a 5 mm diameter window. After the measurement, the operations shown in Table 2 below were performed.

[0042]

[Table 2] Background removal: use of the Shirley method Energy range of C1s: 281.5 to 296 eV Energy range of Li1s: 53 to 62 eV Smoothing operation of data: none Energy shift: peak top of Li1s becomes 57 eV Compensated energy scale

After measuring each of the electrodes, an X-ray photoelectron spectroscopic curve was prepared for carbon and lithium. Furthermore, in order to identify the carbonaceous electrode before charge / discharge, the original passivation layer, and the carbonaceous substance belonging solely to the binder, the X-ray photoelectron spectroscopy was performed on the carbonaceous electrode not subjected to the charge / discharge cycle. The measurement was performed (see FIG. 4). In addition, in order to accurately calculate the relative thickness index (to carbon) of the passivation layer formed by performing the charge / discharge cycle, all the carbonaceous materials measured for the carbonaceous electrode subjected to the charge / discharge cycle were measured. It is necessary to subtract the peak areas of all the carbonaceous materials at the 1s level measured for the carbonaceous electrode not subjected to the charge / discharge cycle from the sum of the peak areas at the 1s level of (see FIG. 5). ). The peak area of the “subtracted” carbonaceous material is around 284.6 eV and is defined under the conditions shown in Table 3 below.

[0044]

[Table 3] Peak full width at half maximum (FWHM): 0.75 eV Gaussian / Lorenzian ratio: 80/20 Peak of peak: 284.6 eV ± 0.2 eV Normalized based on the measured intensity of the spectrum at the carbon 1s level at 284.6 eV.

The relative thickness index of the passivation layer is given by the following formula (I)
Was calculated by

[0046]

## EQU5 ## Relative thickness index = A [C1s (2)] / A [C1s (1)] (I)

In the formula, A [C1s (1)] has a peak apex of 284.4 to 28 measured by X-ray photoelectron spectroscopy.
The peak area of the carbon 1s level present at 4.8 eV is represented, and A [C1s (2)] represents the peak area of all carbon 1s levels measured by X-ray photoelectron spectroscopy.

The relative lithium ion content index of the passivation layer was calculated by the following equation (II).

[0049]

(6) Relative lithium ion content index = A [Li1s] / A [C1s (2)] (II)

In the formula, A [Li1s] represents the peak area of all lithium 1s levels measured by X-ray photoelectron spectroscopy.

Based on the above calculations and the calculation of the initial charge / discharge efficiency, the results shown in Tables 4 and 5 were obtained.

[0052]

[Table 4]

[0053]

[Table 5]

As is clear from Tables 4 and 5, a lithium ion battery using the additive of the present invention and having a relative thickness index and a relative lithium ion content index of the passivation layer within the limits of the present invention ( Examples 1 to 3) show that the initial charge / discharge efficiency is substantially increased as compared with the batteries (Comparative Examples 1 and 2) outside the limited range of the present invention.

The above description and drawings merely illustrate and illustrate the invention, but the invention is not limited thereto. Various changes and modifications of the present invention are possible without departing from the scope of the invention.

[0056]

According to the present invention, gas generation in a battery due to decomposition of a solvent used in combination with an electrolyte is prevented, and gas is substantially removed during decomposition of the additive itself during cycling and storage of the battery. Lithium ion batteries and electrolysis processes with additives that do not occur are provided, and their industrial value is high.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of an initially charged lithium ion battery of the present invention.

FIG. 2 is a schematic diagram of a lithium ion battery in a first initial charge.

FIG. 3 is a flowchart of the electrochemical process of the present invention.

FIG. 4 shows a typical X-ray photoelectron spectroscopy spectrum of a carbonaceous electrode without a charge / discharge cycle.

FIG. 5 shows a typical X-ray photoelectron spectroscopy spectrum of a carbonaceous electrode subjected to one charge / discharge cycle.

[Explanation of symbols]

 10: Lithium ion battery 12: First electrode 14: Second electrode 16: Electrolyte 18: Solvent 22: Additive 24: Carbonaceous surface 40: Passive layer

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Kazuko Otani 1000 Kamoshita-cho, Aoba-ku, Yokohama-shi, Kanagawa Prefecture Inside Mitsubishi Chemical Research Institute (72) Inventor Eitaro Takahashi 1000 Kamoshita-cho, Aoba-ku, Yokohama-shi, Kanagawa Mitsubishi (72) Inventor Kenji Okahara 1000 Kamoshita-cho, Aoba-ku, Yokohama-shi, Kanagawa Prefecture Mitsubishi Chemical Corporation Yokohama Research Laboratory F-term (reference) 5H003 AA03 AA04 BA07 BB03 BC05 BD00 5H014 AA06 BB12 CC01 EE01 HH00 5H029 AJ04 AJ05 AJ07 AK06 AL12 AM01 AM02 AM03 AM04 AM05 AM06 BJ03 CJ11 DJ08 EJ11 HJ00

Claims (16)

[Claims] A first electrode, at least one of which is a carbonaceous electrode;
A lithium ion battery comprising an electrode and a second electrode, an electrolyte, and a passivation layer formed on a surface of the carbonaceous electrode, wherein the passivation layer includes at least carbon, lithium, an additive and / or The following equation, which contains the reaction product of the carbonaceous electrode and the additive and is related to carbon and lithium measured by X-ray photoelectron spectroscopy in a discharge state after one or more cycles of charge / discharge. Lithium having a relative thickness index represented by (I) of about 10 to 90 and a relative lithium ion content index of the following formula (II) of about 0.1 to 0.7. Ion battery. (1) Relative thickness index = A [C1s (2)] / A [C1s (1)] (I) Relative lithium ion content index = A [Li1s] / A [C1s (2)] (II) (where A [C1s (1)] represents the peak area of the carbon 1s level having a peak top at 284.4 to 284.8 eV, measured by X-ray photoelectron spectroscopy, and A [C1s
(2)] represents the peak area of all carbon 1s levels measured by X-ray photoelectron spectroscopy, and A [Li1s] represents the peak area of all lithium 1s levels measured by X-ray photoelectron spectroscopy. Represents the peak area. ) 2. The method according to claim 1, wherein the additive or at least one of the reaction products of the additive causes generation of gas due to decomposition of components in the electrolytic solution or decomposition of the additive or reaction product of the additive in the passive layer. The lithium ion battery according to claim 1, wherein the lithium ion battery is prevented. 3. The passivation layer has a relative thickness index of about 20-80.
The lithium ion battery according to claim 1, wherein 4. The method according to claim 1, wherein the relative thickness index of the passivation layer is about 30 to 70.
The lithium ion battery according to claim 1, wherein 5. The lithium ion battery according to claim 1, wherein the passivation layer has a relative lithium ion content index of about 0.15 to 0.6. 6. The lithium ion battery according to claim 1, wherein the passivation layer has a relative lithium ion content index of about 0.2 to 0.5. 7. The passivation layer having a relative thickness index of about 20-80.
The lithium ion battery according to claim 1, wherein the passivation layer has a relative lithium ion content index of about 0.15 to 0.6. 8. The passive layer having a relative thickness index of about 30 to 70.
The lithium ion battery according to claim 1, wherein the passivation layer has a relative lithium ion content index of about 0.2 to 0.5. 9. A method according to claim 1, wherein at least one of the first electrodes is a carbonaceous electrode.
An electrochemical process in a lithium ion battery comprising an electrode and a second electrode, an electrolyte containing at least one component, and an additive that associates with the electrolyte and at least one of the electrodes with a carbonaceous electrode. And (b) satisfying the following conditions (a) and (b). (A) charging a lithium ion battery, and forming a passivation layer on the carbonaceous electrode surface by a chemical reaction between the carbonaceous electrode surface and an additive, and (b) the passivation layer comprises: At least carbon, lithium, an additive and / or a reaction product of the additive with the carbonaceous electrode,
(C) The passivation layer is represented by the following formula (I) related to carbon and lithium measured by X-ray photoelectron spectroscopy in a discharge state after at least one cycle of charge / discharge. The relative thickness index is about 10 to 90, and the relative lithium ion content index represented by the following formula (II) is about 0.1 to 0.7. Relative thickness index = A [C1s (2)] / A [C1s (1)] (I) Relative lithium ion content index = A [Li1s] / A [C1s (2)] (II) (where A [C1s (1)] represents the peak area of the carbon 1s level where the peak is present at 284.4 to 284.8 eV as measured by X-ray photoelectron spectroscopy, and A [C1s
(2)] represents the peak area of all carbon 1s levels measured by X-ray photoelectron spectroscopy, and A [Li1s] represents the peak area of all lithium 1s levels measured by X-ray photoelectron spectroscopy. Represents the peak area. ) 10. The process of claim 9, further comprising:
Preventing the permeation of one or more electrolyte components through the passivation layer to substantially prevent gas generation in the battery due to decomposition of the components in the electrolyte; So that the occurrence of
10. The electrochemical process according to claim 9, comprising the step of decomposing one or more additives or reaction products with the additives in the passivation layer. 11. The relative thickness index of the passivation layer is about 20-8.
The electrochemical process according to claim 9 or 10, wherein the value is 0. 12. The passivation layer having a relative thickness index of about 30-7.
The electrochemical process according to claim 9 or 10, wherein the value is 0. 13. The electrochemical process according to claim 9, wherein the passivation layer has a relative lithium ion content index of about 0.15 to 0.6. 14. The electrochemical process according to claim 9, wherein the passivation layer has a relative lithium ion content index of about 0.2 to 0.5. 15. The passive layer having a relative thickness index of about 20-8.
15. The electrochemical process according to any of claims 9 to 14, wherein the passivation layer has a relative lithium ion content index of about 0.15 to 0.6. 16. The passivation layer having a relative thickness index of about 30-7.
15. The electrochemical process according to any of claims 9 to 14, wherein the passivation layer has a relative lithium ion content index of about 0.2 to 0.5.