1. Field of the Invention
The present invention discloses a manufacturing method of a battery electrode.
More particularly, the present invention discloses a manufacturing method of a battery electrode consisting primarily of iron.
2. Description of the Prior Art
Generally, a nickel-iron battery is structured with a negative electrode using ferric powder, a positive electrode using nickel hydroxide, electrolytic solution generally being potassium hydroxide solution, and a separating coating between the electrodes to separate the electrodes thereof. The capacity of the ferric electrode of a nickel-iron battery was limited in the past such that the overall energy density of a battery was only 50 Wh/kg and the power density thereof was also merely 100 W/kg, on top of high self-discharge effect. Therefore, nickel-iron batteries were gradually replaced by lead acid batteries, lithium batteries, etc. in the 1970's. However, compared with other batteries, nickel-iron batteries still hold advantages such as extremely long cycle period (>1000 cycle), over-charge and -discharge endurance, sufficient source materials, and eco-friendly, etc.
U.S. Pat. No. 4,356,101 of Jackovitz et al. filed in 1982 discussed reducing ferric oxide prepared from ferric sulfate as precursor with hydroxide at 700° C., thereby producing active iron powder with a capacity as high as 620 mAh/g; however, whether it was the actual cyclic capacity or the first-time discharge capacity was not elaborated. Research document of Huang published in 2007 also indicated that using nano-iron micro-particles prepared by chemical reduction as the material for ferric electrodes could provide 200 mA/g-Fe current with capacity up to 510 mAh/g-Fe, without applying any conductive adjuvant and activator. This implies that high surface area ratio of nano-iron micro-particle indeed effectively enhances utilization of the ferric atoms. Nevertheless, electrical capacity of a nano-iron electrode is different from that of a traditional battery electrode in that the former will decrease as the number of charge-discharge cycles increase (See
Various disadvantages mentioned above exist for the ferric electrode of nickel-iron batteries. Therefore, it is necessary to provide a battery electrode with better charge-discharge cycle characteristics and large current capacity to solve issues faced with present nickel-iron batteries.
To overcome the disadvantages discussed above, the present invention discloses a manufacturing method of a battery electrode. The method includes providing a reducing reagent, a conductive adjuvant, and a solution comprising ferric ions; next applying the conductive adjuvant into the solution to form a first mixture solution, which is then mixed with the reducing reagent to form a second mixture solution; then isolating a composite micro-particle comprising at least one of conductive substances from the second mixture solution with a magnet; and finally mixing an adhesive reagent with the composite micro-particle to form a coating reagent, and applying the coating reagent onto a metal mesh.
Thus, the main purpose of the present invention is to provide a manufacturing method of a battery electrode to enable the electrode consisting primarily of ferric ions with better charge-discharge cycle.
The other objective of the present invention is to provide a manufacturing method of a battery electrode to produce a battery electrode with large current capacity.
The present invention discloses a manufacturing method of battery electrode materials, wherein physical and chemical principles applied are known to those skilled in the art, and thus will not be described in detail hereinafter. Meanwhile, it is to be understood that drawings corresponding to the following descriptions are to illustrate demonstrations related to characteristics of the present invention, not and no need to be fully drawn based on actual conditions.
Refer to
In the foregoing embodiment, the reducing reagent consists of a strong reducing reagent such as, but not limited to, NaBH4 or KBH4, and pure water. The conductive adjuvant may comprise a metallic salt such as Co, Ni, Cu, Sn, Sb, Bi, In, Au, Pb and Cd solutions, or may be directly applied of an extremely fine metal micro-particle or metal compound in the form of powder, filament, slice, etc. Taking the metal micro-particle for example, it is a micro-particle structure made up of pure metal atoms, and may further take the form of powder, filament, or slice. In the example of the metal compound, it refers to metal oxide or nitride, etc.
Further, the carbon substance may be carbon black, carbon nanotube, or graphite. In addition, the solution comprising the ferric ions discussed in the embodiment is soluble ferric compound solution, e.g. FeSO4, Fe(NO3)3, FeCl3, etc. The adhesive reagent is made up of Teflon.
Moreover, in the foregoing embodiment, an inhibitor may further be applied, wherein the inhibitor comprises molybdate, phosphate, organophosphorus compound, silicate, chromate, long carbon chain organic compound with polarized base group, surfactant, etc., to retard the self-discharge effect of the ferric electrode by various mechanisms.
Further, the manufacturing method disclosed in the foregoing embodiment utilizes chemical reducing deposition, producing micro-particles with very small diameters, wherein the iron micro-particle is of nano-scale to enable compact combination of the conductive adjuvant and the active iron micro-particle. In addition, a mass of heterogeneous micro-particles are distributed evenly in the electrode, serving as the place where a core is precedingly formed after dissolving in the crystallized ferric ions during charging, to effectively avoid the diameter from increasing, enabling the electrode to have excellent charge-discharge characteristic and large current capacity.
With reference to
The present invention will be described with reference to the following example, which is not to limit privileges of the claims of the present invention.
At first, dissolve 0.1 mole of sodium borohydride (NaBH4) in 100 ml pure water to serve as the reducing reagent. Then, slowly mix the 100 ml mixture solution containing 0.025 mole of FeSO4.7H2O and 0.0025 to 0.05 mole of metallic salt or micro conductive substance with the reducing reagent, enabling the metallic salt or the micro conductive substance and ferric sulfate to generate reduction reaction together, forming the composite micro-particle consisting of the conductive substance and the ferric ions. The metallic salt may consist of Co, Ni, Cu, Sn, Sb, Bi, In, Ag, Au, Pb or Cd, and the micro conductive substance may be metal powder, metal filament, metal slice, carbon black, carbon nanotube, or graphite. After the reduction is completed, rinse several times by pure water, followed by isolating with a magnet to obtain the composite micro-particle consisting of the ferric ions and the conductive substance. Add into the composite micro-particle perfluoroethylene (Teflon, PTFE) with a weight percentage of 10% to serve as the adhesive reagent and mix up to prepare the coating reagent, which is then applied onto the current collecting mesh to produce the electrode.
What is disclosed above is only the preferred embodiments of the present invention, not to limit privileges of the claims thereof. Meanwhile, descriptions mentioned above should be understood and performed by those skilled in the art; therefore, any other changes or amendments applied under the spirits revealed in the present invention should be included in the claims appended.
Number | Date | Country | Kind |
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098124508 | Jul 2009 | TW | national |