JP3133308B2 - Manufacturing method of electrochemical cell - Google Patents

Description

The present invention relates to a secondary electrochemical cell.

Is known manganese oxide as a primary cathode material (MnO ₂₎ electrochemical cells, it has been reported to have only recharge capacity is limited. The present invention provides Mn as a cathode material.
Based on the finding that when an electrochemical cell containing O ₂ is assembled in a charged state and then discharged, the resulting battery can function as a secondary battery.

Accordingly, the present invention provides (a) an anode containing an alkali metal as an active anode material,
Assembling a solid electrochemical cell having a solid alkali metal ion conductive electrolyte and a cathode containing manganese (IV) oxide as the active cathode material; and (ii) conditions for in situ conversion of the cathode material to a rechargeable material. A method for manufacturing a secondary electrochemical cell, comprising discharging the battery below.

In embodiments of the present invention described below, the resulting battery can be recharged at high temperatures and then discharged, and can be repeatedly recharged and discharged without loss of capacity after the first discharge cycle. It was surprisingly found.

In the step (a), the battery is manufactured in a laminated form such as a film composed of an anode, an electrolyte, and a cathode constituting a flexible sandwich structure. In the step (a), for example, the flexible laminate is stacked, wound or folded in a desired shape, and then housed in a flexible package or casing, and terminals are provided so that the battery can be discharged in the step (b).

In the step (b), the conditions for converting the cathode material are most preferably high temperature conditions, for example, in the range of 100 ° C to 150 ° C.

Hereinafter, the components of the battery used in the present invention and obtained by processing will be described in detail.

Anode The anode may be, for example, an alkali metal such as lithium (which is preferred), sodium or potassium,
Alternatively, it can be constituted entirely in a form such as an alloy or a mixture thereof (the form is capable of electrochemically releasing a metal from the form when the battery is discharged).
If desired, the active anode material may be carried as an underlying structure of a support material.

Electrolyte The electrolyte may be, for example, a solid polymer electrolyte comprising a complex of a solid polymer and an alkali metal salt. Here, the polymer can form a donor-acceptor type bond with an alkali metal ion and can conduct the alkali metal ion.

Such electrolytes are known to those skilled in the art and are described, for example, in European Patent Publication No. 0013199 (corresponding to US Pat. No. 4,303,748) and British Patent Publication No. 2139410 (US Pat.
(Corresponding to No. 7440). As a specific example, for example, poly (ethylene oxide) (hereinafter simply referred to as “PE
Say O ") and a plastic polymer material such as poly (propylene oxide), alkali metal salts (preferably lithium salt, the anion of the alkali metal salts, for ^{example, I -, Br -, ClO} 4 -, SCN ^- or F ₃ CSO ₃ ^- a is) complex and the like with.

Cathode MnO ₂ used for the cathode of the battery in the step (a) is MnO ₂ of a grade for a storage battery used for a commercial primary battery. Preferably, when the cathode is MnO _2, the electrolyte material and a solid alkali metal ion conducting polymer such as that used as the electrolyte as it is, desired, it is constructed as a composite structure including a conductive medium, such as graphite .

In the step (b), the structure of MnO ₂ is reconverted by the entry of an alkali metal such as lithium, for example, and the spinel compound {Mn ₂ O ₄ (wherein, Μ is an alkali metal)
It is considered that this spinel-type compound gives the battery the characteristics as a secondary battery. In fact, it is known to use LiMn ₂ O ₄ as the cathode of a secondary battery (see, for example, GB-A-2122412, GB-A-2196785 and EP-A-0279235). However, none of the above describes producing LiMn ₂ O ₄ electrochemically in situ.

 Hereinafter, the present invention will be described in more detail with reference to Examples.

EXAMPLES (A) Assembly of Battery Components and Composite Cathode of Battery Battery-grade MnO ₂ was dried at 170 ° C. for 14 hours under a partial pressure of 10 ⁻² torr (C.10 ⁻² torr). MnO ₂ (22.62g),
Ketjenblack Carbon
(1.10g), acetone (120ml) and Span80
In a 250 ml pot containing 4 large alumina balls and 16 small alumina balls,
Ball milled for 2.5 hours. PEO (3.00 g, manufactured by Union Carbide, molecular weight 4,000,000) was added to the pot, and ball milling was continued for another 10 minutes. Then, LiClO ₄ (1.
21 g) and acetonitrile (120 ml) are added, and the mixture is diluted with 1
Ball milled for hours.

The mixture was cast by doctor blade solution casting using a 0.5 mm blade on a nickel foil functioning as a current collector. The resulting composite cathode is 43 micrometers thick, about 1.0 mA based on 308 mA hg ^{-1 of} Mno _2.
hcm- ² . The composition of the electrolyte in the composite cathode was PEO ₁₂ : LiClO ₄ .

The above preparations were performed in an open laboratory under normal atmospheric conditions. Dry the composite cathode in a drying room (temperature: 20 ° C, dew point: -30
° C), the final drying was performed for several days, and processed into a battery (see the description below).

Electrolyte A mixture of LiClO ₄ (1.21 g) and acetonitrile (120 ml) ball-milled for one hour was cast with a doctor blade solution using a 0.5 mm blade to prepare a polymer electrolyte to be used as an electrolyte for the battery. . That is, the mixture was cast on a silicone release paper,
₁₂ : An electrolyte having a composition of LiClO ₄ was obtained. The preparation and transfer of the electrolyte were performed under the same conditions as those described for the composite cathode.

Anode One piece of lithium foil (ex Lithco, 4
0.0 cm ² , 150 micrometers) was wrapped around a small piece of nickel foil that served as the anode current collector.

Battery Using a thin blade, one piece of the dried composite cathode (9 cm × 6
cm; 54 cm ² ). After measuring the weight of this cathode,
The thickness before and after winding was measured. 6 layers of said electrolyte with equal area (14 micrometers)
Was placed on the cathode, and the components were laminated under high temperature and vacuum. The anode was placed on the electrolyte and the entire cell was vacuum laminated at high temperature. To avoid possible short circuits, the edges of the cells were insulated using high temperature insulating tape and the cells were vacuum packaged using standard packaging materials.

(B) Discharge of Battery The battery was placed in an oven at 120 ° C., connected to a battery cycle rig, and discharged at a rate of C / 10 using a constant current.

(C) Test of discharged battery The battery was charged to a maximum voltage of 3.25 V at a constant current at a rate of C / 10. The battery was heavily charged and was able to discharge about 60% of the theoretical discharge capacity in the second discharge cycle.
When the subsequent cycle was performed under the same conditions, the next 20
The discharge loss was found to be small over the number of cycles. FIG. 1 shows a fourth discharge-charge cycle of the battery. Figure 2 shows the first forming
After discharge, there is a slight or no decrease in capacity over the next 20 cycles. This test was performed at 120 ° C.

[Brief description of the drawings]

FIG. 1 is a graph of battery voltage versus theoretical capacity% of the fourth discharge-charge of a battery manufactured by the method of the present invention. FIG. 2 is a graph of the theoretical capacity% with respect to the cycle number of the battery manufactured by the method of the present invention.

────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Raymond John Powell Oxfordshire OX110RA Harwell Laboratory Building 329 United Kingdom Atomic Energy Conservation Patents Branch (56) References JP-A-62-108456 (JP, A) JP-A-2-82450 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01M 10/40

Claims (4)

(57) [Claims] (1) assembling a solid electrochemical cell having an anode containing an alkali metal as an active anode material, a solid electrolyte capable of conducting alkali metal ions, and a cathode containing manganese (IV) oxide as an active cathode material; And (b) discharging the battery under the condition where the temperature is raised to a temperature in the range of 100 to 150 ° C., and converting the cathode material into a spinel compound
MMn ₂ O ₄ (M is an alkali metal) comprising the step of converting in situ the cathode material capable of recharging includes a method for manufacturing a rechargeable electrochemical cell. 2. The method of claim 1, further comprising the step of recharging the battery. 3. An electrolyte comprising a complex of a solid polymer and an alkali metal salt, said polymer being capable of forming a donor-acceptor type bond with the alkali metal ion and being capable of conducting the alkali metal ion. The method according to claim (1) or (2). 4. The cathode according to claim 1, wherein the cathode is constructed as a composite structure containing manganese (IV) oxide and a solid polymer electrolyte substance capable of conducting alkali metal ions. the method of.