KR19980059079A - Activation method of active material for positive electrode - Google Patents

Abstract

Method of Activation of a Battery Including a Process of Supplying a Pulse Current in a High Temperature Atmosphere After Producing a Battery by a Positive Plate, a Negative Plate, and an Electrolyte The battery activation method uses a pulse current, and thus a thin and dense plating layer is applied by applying a high current at a pulse-on time. By lowering the contact resistance and increasing the electrical conductivity, it is possible to obtain a plating layer of excellent conductivity, effectively obtain the properties of the plating layer to be obtained, and also to pulse-off the concentration polarization phenomenon generated during the pulse-on time By controlling the diffusion of reactive species in time, there is an advantage that can selectively occur the desired reaction.

In addition, the efficiency of the Co additive can be increased by adding a small amount to increase the utilization, and thus can be effectively utilized in manufacturing a high capacity battery.

Description

Activation method of active material for positive electrode

[Prior art]

Recently, with the trend toward miniaturization and lightening of new portable electronic devices such as camera-integrated VTRs, audio, laptop personal computers, portable telephones, and the like, there is a need for a technology for increasing the performance and capacity of batteries used as power sources for these devices. In particular, efforts are being made to develop technologies that reduce manufacturing costs of these batteries, particularly in economic terms. In general, batteries include primary batteries used for single use, such as manganese batteries, alkaline batteries, mercury batteries, and silver oxide batteries, Ni-MH (nickel-metal hydride) batteries using lead-acid batteries, and metal hydrides as negative active materials, and sealed nickel. Rechargeable batteries such as cadmium and lithium-metal batteries, lithium-ion batteries (LIB: Lithium Ion Battery), lithium-ion batteries such as Lithium Polymer Battery (LPB), and the like; It can be divided into fuel cell, solar cell and the like.

Among them, primary batteries have a small capacity, short lifespan, and cannot be recycled, causing environmental pollution. On the other hand, secondary batteries can be recharged and used for a long time, and voltage is much higher than that of primary batteries. It is excellent in terms of efficiency and efficiency, and generates less waste, which is also excellent in environmental protection.

Among the secondary batteries described above, nickel-based batteries are most frequently used because they have the most established recycling technology, which is excellent in environmental protection, and enables high performance of the batteries.

The Ni electrode used as the positive electrode in the Ni-MH secondary battery is changed through a redox process as shown in the following Reaction Formula (I) during the charge and discharge process.

^{_{Ni (OH) 2 + OH -}} ↔ NiOOH + H 2 O + e - ---- (Ⅰ)

In the charging and discharging process, NiOOH has high conductivity while Ni (OH) ₂ does not have good conductivity, so the overpotential is largely generated in the reaction scheme (I) during charging to generate oxygen gas initially. As a result, the capacity of the battery is reduced by reducing the utilization rate of the positive electrode active material, and there is a problem in that the negative electrode is oxidized and deteriorated due to the generation of oxygen gas.

In order to solve this problem, a positive electrode active material composition in which a cobalt compound (Co, CoO, CoOOH, Co ₂ O ₃ , Co ₃ O ₄ ), which is a conductive agent, is added to a composition for manufacturing a positive electrode of a nickel-based battery, is used. Thus, a slurry is prepared by mixing a cobalt compound and Ni (OH) ₂ as an active material, followed by filling in a nickel foam to form an electrode, or mixing an active material and a Co compound with a KOH solution to form a Co (OH) ₂ . The electrode was prepared by forming a circumference around the active material to increase the dispersibility of the Co compound. The added cobalt is electrochemically oxidized at the initial stage of supercharging of the cell to form cobaltoxyhydride (CoOOH), which is a conductive material on the surface of nickel hydroxide, as shown in the following scheme (II).

^{_{Co (OH) 2 + OH -}} ↔ CoOOH + H 2 O + e - ----- (Ⅱ)

The electrode produced by the above method was activated by a constant current charging method.

As described above, as a method of activating a battery by using a constant current, there are a case of using a high current and a method of using a constant current. When activating the battery with high current, that is, high density, the nucleation site can be formed and grown so that the CoOOH layer plated around the active material Ni (OH) ₂ can be densely formed. If the overvoltage is increased quickly to reach a potential at which Ni (OH) ₂ is oxidized to NiOOH, the formation of CoOOH and NiOOH is not preferable.

Because of this problem, in the past, in most cases, it was charged with a low current of 0.1C. In this case, there is an advantage in that NiOOH is formed after CoOOH is formed. In addition, the activation time is long, there is a process difficulty.

The present invention is to solve the above problems, an object of the present invention is to form an active material coated with a conductive agent, it is easy to activate the electrode, the activation of a battery that can manufacture a high capacity battery To provide a way.

1 is a cross-sectional view schematically showing an active material for a positive electrode after activating a battery using a pulse current represented by a current versus time graph under a high temperature atmosphere according to the method of the present invention.

2 is a cross-sectional view schematically showing an active material for a positive electrode after activating a battery using a constant current represented by a current versus time graph according to a conventional method.

3 is a cross-sectional view schematically showing a negative electrode active material activated in a high temperature atmosphere according to the method of the present invention.

In order to achieve the above object, the present invention provides a method for activating a battery comprising the step of supplying a pulse current in a high-temperature atmosphere after the battery is prepared by a positive electrode plate, a negative electrode plate, an electrolyte solution.

In this invention mentioned above, it is preferable that the temperature of the said high temperature atmosphere is 20-80 degreeC.

In the present invention described above, the pulse-on time and the pulse-off time of the pulse current are preferably 10 msec to 100 msec.

EXAMPLE

Hereinafter, preferred examples and comparative examples of the present invention are described. However, the following examples are only one preferred embodiment of the present invention and the present invention is not limited to the following examples.

(Example 1)

On both sides of the separator, a positive electrode plate and a negative electrode plate were disposed around the winding shaft, and the positive electrode plate, the negative electrode plate, and the separator were wound around the winding shaft, stored in a can, an electrolyte solution was injected, and then formed and assembled to manufacture a battery. The cell was supplied with a current of 10 msec (pulse-on time) in a 20-80 ° C. atmosphere, and then activated using a pulse current that cuts off for 10 msec (pulse-off time).

(Example 2)

On both sides of the separator, a positive electrode plate and a negative electrode plate were disposed around the winding shaft, and the positive electrode plate, the negative electrode plate, and the separator were wound around the winding shaft, stored in a can, an electrolyte solution was injected, and then formed and assembled to manufacture a battery. The cell was supplied with a current for 100 msec (pulse-on time) under a 20-80 ° C. temperature atmosphere, and then activated using a pulse current that cuts off for 100 msec (pulse-off time).

(Comparative Example)

On both sides of the separator, a positive electrode plate and a negative electrode plate were disposed around the winding shaft, and the positive electrode plate, the negative electrode plate, and the separator were wound around the winding shaft, stored in a can, an electrolyte solution was injected, and then formed and assembled to manufacture a battery. The battery was energized and activated.

By using a pulse current as in the present invention, by applying a high current in the pulse-on time to obtain a thin and dense plated layer, it is possible to obtain a plated layer having excellent conductivity by reducing the contact resistance and increasing the electric conductivity. It can be effectively obtained, and also by controlling the concentration polarization phenomenon generated in the pulse-on time through the diffusion of the reactive species in the pulse-off time there is an advantage that can selectively occur the desired reaction.

In addition, the efficiency of Co additives can be increased to increase the efficiency even with the addition of a small amount, so it can be effectively utilized in the manufacture of high capacity batteries, and the pulse charging can be omitted in a high temperature atmosphere to omit separate chemical conditions and increase the activity of the negative electrode. have.

Claims (3)

A method of activating a battery comprising the step of manufacturing a battery with a positive electrode plate, a negative electrode plate, and an electrolyte solution, and then supplying a pulse current under a high temperature atmosphere. The method of activating a battery according to claim 1, wherein the temperature of the high temperature atmosphere is 20 to 80 ° C. The method of claim 1, wherein the pulse-on time and pulse-off time of the pulse current are 10 msec to 100 msec.