JPS58161260A - Cell - Google Patents

Abstract

PURPOSE:To eliminate the initial voltage drop by providing a negative pole employing a light metal as an active substance and a positive pole employing carbon fluoride as main active substance while added with specific chrome oxide. CONSTITUTION:In a cell having a negative pole employing light metal such as Li as an active substance and a positive pole employing nonaqueous electrolyte and carbon fluoride as main active substance, a chrome oxide shown by CrxOy (1.5<y/x<3) is added in the positive pole. consequently in the initial discharge, high potential chrome oxide is discharged precedently to increase the initial discharge voltage to provide the flat voltage characteristic essential to a carbon fluoride/Li cell and high discharge capacity.

Description

[Detailed Description of the Invention] The present invention eliminates the drop in the initial discharge voltage of a battery composed of a negative electrode made of a light metal such as lithium as an active material, a nonaqueous electrolyte, and a positive electrode made of fluorocarbon as a living material. This is what I did.

The above-mentioned fluorocarbon/lithium battery has high energy density, good storage performance, long-term operation reliability, leakage resistance, temperature characteristics, flat voltage stability, etc. It is already widely used as the best battery. However, along with these excellent characteristics, there is also a characteristic that the initial discharge voltage is slightly lower than the flat voltage, and depending on the device, the initial voltage drop may become an obstacle in the design. Conceptually, as shown in Figure 1, the flat voltage (-)
At the beginning of the discharge, as shown in (b), the voltage is slightly lower than that in (a) until the voltage reaches . In order to raise the voltage in (b) above (a) and still take advantage of the excellent characteristics of fluorocarbon/lithium batteries, especially the stability of energy density and flat voltage, a high-potential positive electrode such as manganese dioxide, etc. Methods of adding active materials have already been proposed, but the effect of the addition decreases due to storage, making them impractical.

The present invention aims to improve the characteristic that the initial discharge voltage of a fluorocarbon/lithium battery drops, and is characterized by adding an intermediate oxide of CrO2 and Cr2O3 to the positive electrode of the battery. be.

FIG. 2 shows the conceptual discharge characteristics of an intermediate oxide of chromium as a positive electrode active material with lithium as a counter electrode in an organic electrolyte. Chromium oxides include Cr2O3゜31, - In addition to CrO3, for example, Cr206. which is obtained by heating CrO3 under pressure. Cr3O8, Cr6o1. , C
Intermediate oxides between Cr2O3 and CrO3 such as rO2 (C
rxOy, 16〈y/x〉3), and although CrO3 and CrO2 have low electrochemical activity, as shown in Fig. 2, fluorocarbon (CF)n
Although it is inferior in voltage flatness and discharge capacity compared to Crsos + Cr 2051 Cr, it is characterized by a high initial discharge voltage, and is relatively superior to Crsos + Cr 2051 Cr among intermediate chromium oxides.
eol has excellent discharge characteristics. This Cr 30
8. Cr2O5+ Cr○2 can be obtained relatively easily at an oxygen pressure of about 20 atm and a nonthermal temperature of 250 to 350°C, but Cr6
o1. Since it can only be obtained under ultra-high pressure of about 10 oO atmosphere, it is somewhat difficult from an industrial perspective.

The present invention utilizes the advantages of the image material and compensates for its disadvantages by adding chromium oxide, which has a high initial discharge potential, to a positive electrode whose main component is fluorocarbon. The aim is to discharge chromium oxide preferentially to increase the initial discharge voltage, and to obtain characteristics that combine the voltage flatness and large discharge capacity inherent to fluorocarbon/lithium batteries. This figure shows a cross section of a battery that was prototyped to experimentally confirm the effects of the invention.

In Fig. 3, 1 is a stainless steel sealing plate;
2 is a negative electrode current collector made of nickel net welded to 1, 3 is a lithium negative electrode crimped to current collector 2, 4 is a separator made of polypropylene nonwoven fabric, 6 is mainly composed of fluorinated graphite,
Acetylene black and fluororesin powder were added thereto in an amount of 5% by weight, and chromium oxide was added in various ratios to be described later, then mixed and pressure molded to produce a positive electrode. 6 is a positive electrode current collector made of expanded titanium metal;
07, which is in close contact with the battery container, is made of stainless steel scale, and a current collector 6 is welded to the inner surface of the battery container.

Reference numeral 8 denotes a polypropylene gasket, which is compressed by folding inward at the opening of the battery container 7 to seal the battery. An electrolytic solution in which lithium fluoroborate was dissolved in a solvent containing a mixture of propylene carbonate and dimethoxyethane at a weight ratio of 1:1 at a concentration of 1 mol/rho was injected into the battery.

In order to confirm the effects of the present invention, various batteries with the above configurations were tested with different cathode formulations, and the diameter was 20 mm and the thickness was 20 mm.
A prototype battery of 1.0 mm in diameter was manufactured and tested, and the results are described below.

Representative examples of chromium oxide include Cr3O8 and C
The details of the batteries prototyped by selecting R206 and varying the amounts added to the positive electrode are shown in the following table.

In addition, Fig. 4 shows the initial discharge characteristics when Cr5o8 is added, Fig. 5 shows the initial discharge characteristics at 20°C and 30Ω load when Cr206 is added, and the initial discharge characteristics at 20°C after 3 months storage at 46°C. ,
The discharge characteristics at 30 KO were also almost unchanged from those shown in FIGS. 4 and 5.

From the following blank page 6, Figures 4 and 5 show that the desired discharge characteristics are obtained by adding chromium oxide, and the initial discharge voltage increases as the amount of chromium oxide added increases.OCr 308 and Cr2
The effect of adding 06 is qualitatively similar, but Cr5o8
When compared with the same amount of chromium oxide added, on the other hand, the characteristics at the end of the discharge show that as the amount of chromium oxide added increases, the flatness slightly deteriorates and the discharge capacity tends to decrease. However, these phenomena at the end of discharge occur when the addition ratio of chromium oxide is 1.
When the temperature is 1:03 or less, it is not noticeable, but it is relatively noticeable up to 1:05. Therefore, taking into account the rise in voltage at the initial stage of discharge, flatness, and capacity, an appropriate addition ratio is about 1:05-03, and if flatness is more important, about 1:05-02 is better.

However, it is desirable to select an appropriate value for these addition ratios depending on the purpose and use, and the best formulation should be determined each time - there is no need to determine it generally.

As described above, the effects of the present invention are extremely significant.

[Brief explanation of the drawing]

Figure 1 is a conceptual characteristic diagram of the initial discharge voltage of a fluorocarbon/lithium battery, Figure 2 is a diagram of the positive electrode discharge characteristics of various chlorine and oxides with the counter electrode ffi IJ lithium, and Figure 3 is the battery used in the experiment. FIG. 4 is a discharge characteristic diagram of various batteries containing Cr3O8, and FIG. 5 is a cross-sectional view of Cr2O. FIG. 2... Negative electrode current collector, 3... Lithium negative electrode, 6... Positive electrode, 6... Positive electrode current collector. Name of agent: Patent attorney Toshio Nakao, 1 person W+
−= Mi doctor 0%1 solution adventure mi

Claims (2)

[Claims] (1) A negative electrode made of a light metal as an active material, a non-aqueous electrolyte, and a positive electrode made of fluorocarbon as a main active material;
A battery characterized by adding a chromium oxide represented by rxOy (where 15<y/x<1). (2) The chromium oxide is Cr5o8 or Cr2O5
The battery according to claim 1, which contains as a main component.