The patent's assignee is Toyota Jidosha Kabushiki Kaisha.
News editors obtained the following quote from the background information supplied by the inventors: "Air batteries are rechargeable batteries that use an elemental metal or metal compound for the negative electrode active material and oxygen for the positive electrode active material. Since oxygen used for the positive electrode active material is obtained from the air, it is not necessary to seal the positive electrode active material in the battery. Accordingly, air batteries are theoretically able to realize greater capacity than secondary batteries using a solid positive electrode active material.
"In a lithium-air battery, which is one type of air battery, the reaction of the following Formula (I) proceeds at the negative electrode during discharge:
"Electrons generated in Formula (I) perform work in an external load via an external circuit, after which they reach the air electrode. Then, lithium ions (Li.sup.+) generated in Formula (I) migrate within an electrolyte retained between the negative electrode and the air electrode from the negative electrode side to the air electrode side by electroosmosis.
"In addition, the reactions of the following Formulae (II) and (III) proceed at the air electrode during discharge:
"The generated lithium peroxide (Li.sub.2O.sub.2) and lithium oxide (LiO.sub.2) accumulate on the air electrode in a solid state.
"During charging, the reverse reaction of Formula (I) proceeds at the negative electrode, while the reverse reactions of Formulae (II) and (III) proceed at the air electrode, thereby causing metal lithium to be regenerated at the negative electrode and enabling redischarging.
"Conventionally, spherical carbon material such as Ketjenblack, etc. has been used as an electrically conductive material in the air electrode. However, in the case of using the spherical carbon material, there has been a problem that the initial capacity is high but the capacity significantly decreases after repeated charging and discharging. As a technique to solve such a problem, Patent Literature 1 discloses techniques related to a metal air secondary battery comprising an air electrode having an air electrode layer including an electrically conductive material, an negative electrode and a nonaqueous electrolyte, wherein the electrically conductive material is needle-shaped carbon of an average aspect ratio of 10 or more."
As a supplement to the background information on this patent application, NewsRx correspondents also obtained the inventor's summary information for this patent application: "Technical Problem
"As a result of diligent researches on the metal air secondary battery disclosed in Patent Literature 1, the inventor of the present invention has found out that the discharge capacity obtainable per one time of discharge has been significantly low.
"The present invention has been achieved in light of this circumstance. An object of the present invention is to provide an air battery comprising a needle-shaped carbon material in an air electrode layer having more reaction starting points of oxygen reduction reaction than conventional carbon materials.
"Solution to Problem
"An air battery of the present invention comprises at least an air electrode, a negative electrode and an electrolyte layer disposed between the air electrode and the negative electrode, wherein the air electrode is provided with at least an air electrode layer, and the air electrode layer contains a needle-shaped carbon material having an average aspect ratio of 10 or more and a DIG ratio of 0.1 or more.
"In the present invention, it is preferable that an average lattice spacing of (002) plane of the needle-shaped carbon material is 0.335 nm or more and less than 0.370 nm.
"In the present invention, the needle-shaped carbon material may have a
"In the present invention, the needle-shaped carbon material may be a cup-stacked carbon nanotube.
"Advantageous Effects of Invention
"Since the air electrode layer of the present invention contains the needle-shaped carbon material having a D/G ratio of 0.1 or more, that is, a carbon material in a shape of needle having more reaction starting points of the oxygen reduction reaction than conventional carbon materials, giving and receiving electrons between the needle-shaped carbon material and more oxygen molecules are capable. As a result, the present invention can realize greater capacity and higher energy density than conventional air batteries.
BRIEF DESCRIPTION OF DRAWINGS
"FIG. 1 is a schematic perspective view of cup-stacked carbon nanotube.
"FIG. 2 is a drawing schematically showing a cross-sectional view sectioned in the direction of lamination of the layer configuration of an example of an air battery according to the present invention.
"FIG. 3 is a schematic perspective view of conventional carbon nanotube."
For additional information on this patent application, see:
Keywords for this news article include: Chalcogens, Toyota Jidosha Kabushiki Kaisha.
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