Chemistry: electrical current producing apparatus – product – and – Regenerating – salvage or repair feature other than only...
Reexamination Certificate
1999-06-23
2001-07-17
Kalafut, Stephen (Department: 1745)
Chemistry: electrical current producing apparatus, product, and
Regenerating, salvage or repair feature other than only...
C429S231950, C429S231100, C429S231300, C429S231200, C423S179500, C423S441000, C423S050000
Reexamination Certificate
active
06261712
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of reclaiming a cathodic active material of a lithium ion secondary battery which is used as a power source for various electronics such as videotape recorders and communication tools.
2. Related Art
Nonaqueous electrolytic batteries attract considerable attention as the battery with a high energy density and have come to be widely used as the power source for electronics along with the recent progress of a variety of down-sized and light-weight electronics such as videotape recorders, communication tools and the like. Among these nonaqueous electrolytic batteries, lithium ion secondary batteries, unlike other secondary batteries, do not contain the metal components of which use must be carefully considered from the standpoint of environmental problems, such as mercury, cadmium and lead, and are also characterized by having a sufficient cycle life. Hence the usage of the lithium ion secondary batteries is steadily increasing. As for materials used for the lithium ion secondary batteries, both of materials currently used and materials proposed for the next generation contain rare metals such as cobalt and the like, which are specified as the national stock material. Hence public attention is focused on the recovery of rare metals from used lithium ion secondary batteries to reuse these metals.
In the above-described circumstances, it has been activated in view of conservation of natural resources, to develop the technology for recycling lithium ion secondary batteries, and the target for reclamation is on the metal compounds used as a cathodic active material such as cobalt compounds, lithium compounds, nickel compounds, manganese compounds and the like.
For example, there is a proposed process for recovering cobalt hydroxide, in which the batteries are calcined and crushed, the crushed batteries are screened after iron is removed from the crushed batteries by means of magnetic separation, the minus sieve of the crushed batteries are dissolved in an acid, and solvent extraction is made on the acid solution, thereby obtaining cobalt hydroxide. This process can yield cobalt hydroxide of a relatively high purity as a recovery product.
In the above process, however, an expensive organic agent is used for precipitation and much electric power is also necessary for recovering lithium by electrolysis which is performed separately from the recovery of cobalt. Therefore, this process has a problem in running cost. Moreover, if the recovered materials, cobalt and lithium, are used in preparation of the cathode of batteries, they must be further refined before blending them to make a starting material for production of the carhodic active material. Therefore, it costs much to apply the above recovery process to reclamation and recycle of the active material.
As clearly understood from the above description, the conventional process for recovering cobalt from lithium ion secondary batteries costs much because of the use of expensive organic agent and has a disadvantage that the metal elements from which the cathodic active material is composed, or lithium and cobalt, are separately recovered and an active material such as can be reused is not directly obtained.
SUMMARY OF THE INVENTION
With these problems in mind, therefore, it is the primary object of the present invention to provide a novel method of reclaiming a cathodic active material from a lithium ion secondary battery, that is, a reclamation method which enables to directly recover the cathodic active material such as bears reusing.
In order to achive the above-mentioned object, a method of reclaiming a cathodic active material from a lithium ion secondary battery having a casing and a content including a cathodic active material, according to the present invention, comprises the steps of: breaking the lithium ion secondary battery and separating the casing and the content to remove the casing from the content; dissolving the content into a mineral acid to separate remaining non-dissolved content from the mineral acid to obtain a liquid containing the cathodic active material; adding a lithium salt to the liquid; and recovering the cathodic active material from the liquid.
In another aspect of the present invention, a method of reclaiming a cathodic active material of a lithium ion secondary battery, wherein the cathodic active material comprises a lithium compound represented by the formula: LiMO
2
, where the letter M represents a transion metal element selected from the group consisting of cobalt, nickel and manganese, the method comprises the steps of: preparing a liquid in which the cathodic active material is dissolved; adding a small amount of a lithium salt into the prepared liquid; producing a precipitate containing lithium element and the transition metal element of the cathodic active material from the prepared liquid; and separating and calcining the precipitate to reclaim a cathodic active material.
The features and advantages of the recovering method according to the present invention over the proposed recovering process will be more clearly understood from the following description of the preferred embodiments of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Batteries, including galvanic cells and battery packs, have, in general, positive and negative electrodes, an electrolyte and a casing for covering these parts. Each of the electrodes comprises a collector which is a main body of the electrode and a layer of an anodic or cathodic active material which is formed on the surface of the collector. The anodic and cathodic active materials are respectively laminated as a film on the surface of each of the collectors by using a binder such as a PVdF, and they work for an exchange of electrons and ions on the surface of the collector. These active materials also serve to protect the surface of the collector. In the lithium ion secondary battery, the cathodic collector is commonly formed of aluminum and the anodic collector is formed of copper. As the anoodic active material, carbon or the like is used, and as the cathodic active material, lithium cobaltate (LiCoO
2
), lithium nickelate (LiNiO
2
) and the like are commonly used.
The layer of cathodic active material is formed using a powder of cathodic active material which is typically represented by a formula: LiMO
2
,wherein the letter M is a transition metal element selected from the group consisting of Co, Ni and Mn. Powdered lithium cobaltate (LiCoO
2
) as an active material can be obtained by calcining a mixture of a powder of a lithium compound and a powder of a cobalt compound to produce lithium cobaltate. The lithium compound and the cobalt compound are, respectively, such a compound as can produce a corresponding oxide by calcination thereof, for instance, oxide, hydroxide, carbonate, carbide and the like, of each of lithium and cobalt. Specific examples of the lithium compound include Li
2
O, Li
2
CO
3
and the like, and those of the cobalt compound include Co(OH)
2
, Co
2
(CO
3
)(OH)
2
, Co
2
O
3
and the like. Here, it should be noted that the mixing ratio of the lithium compound and the cobalt compound is commonly regulated so that the content of lithium is slightly in excess of its stoichiometric amount. The excess amount of lithium compound remains in the calcined product, which is possibly removed by washing the calcined product with cleaning water. In a case of the cathodic active material being lithium nickelate, it is similarly obtained by calcining a mixture of a powder of a lithium compound and a powder of a nickel compound to produce lithium nickelate. Examples of the nickel compound include Ni(OH)
2
, Ni
2
(CO
3
)(OH)
2
, Ni
2
O
3
and the like.
In the present invention, the cathodic active material of the used batteries is reclaimed by preparing a liquid dissolving the cathodic active material, recovering the cathodic active material in the form of a mixture of the lithium compound and the cobalt compound or the nickel compo
Hayashi Masaru
Sasaki Kunihiko
Tachibe Tetsuya
Tezuka Fuminobu
Tomioka Yuki
Kabushiki Kaisha Toshiba
Kalafut Stephen
Martin Angela J.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
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