Sumitomo Chemical Company, Limited

Masami Makidera

Taketsugu Yamamoto

Satoru Kuze

Takeshi Hattori

Maiko Sakai

The present invention provides a sodium secondary battery capable of reducing the amount of lithium used, and ensuring a larger discharge capacity maintenance rate when having repeated a charge and discharge, as compared with conventional techniques; and a mixed metal oxide usable as the positive electrode active material therefor. A mixed metal oxide of the present invention comprises Na and Mwherein Mrepresents three or more elements selected from the group consisting of Mn, Fe, Co and Ni with an Na:Mmolar ratio being a:1 wherein a is a value falling within the range of more than 0.5 and less than 1. Also, a mixed metal oxide of the present invention is represented by the following formula (1):NaMO&#x2003;&#x2003;(1)wherein Mand a each have the same meaning as above. The positive electrode active material for secondary batteries of the present invention comprises the mixed metal oxide above.

Mixed metal oxide and sodium secondary battery

Disclosed is a mixed metal oxide comprising Na, M, and M, where Mrepresents at least one element selected from the group consisting of Mg, Ca, Sr, and Ba; and Mrepresents at least one element selected from the group consisting of Mn, Fe, Co, and Ni, wherein the molar ratio of Na:M:Mis a:b:1, where a is a value within the range of not less than 0.5 and less than 1; b is a value within the range of more than 0 and not more than 0.5; and 'a+b' is a value within the range of more than 0.5 and not more than 1. An electrode having an active material containing the mixed metal oxide is also disclosed. Further disclosed is an electrode containing the electrode active material as well as a sodium secondary battery comprising the electrode as a positive electrode.

Mixed metal oxide, electrode, and sodium secondary battery

A sodium secondary battery capable of reducing the amount used of a scarce metal element such as lithium and cobalt and moreover, ensuring a larger discharge capacity after repeating charge/discharge as compared with conventional techniques, and a mixed metal oxide usable as the positive electrode active material therefor. The mixed metal oxide comprises Na, Mn and Mwherein Mis Fe or Ni, with a Na:Mn:Mmolar ratio being a:(1&#x2212;b):b wherein a is a value falling within the range of more than 0.5 and less than 1, and b is a value falling within the range of from 0.001 to 0.5. Another mixed metal oxide is a mixed metal oxide represented by the following formula (1): NaMnMO(1) wherein M, a and b each have the same meaning as above. The positive electrode active material for sodium secondary batteries comprises the mixed metal oxide above.

Disclosed are a positive electrode active material and a method for producing an olivine-type phosphate. The positive electrode active material comprises an olivine-type phosphate represented by the following formula (I), wherein the maximum peak in an X-ray diffraction pattern obtained using a CuK&#x3b1; ray is the peak of the (031) plane of the olivine-type phosphate and the half-value width of the peak is 1.5&#xb0; or less: AMPO(I), wherein A represents one or more elements selected from among alkali metals; M represents one or more elements selected from among transition metals; a is from 0.5 to 1.5; and b is from 0.5 to 1.5. The method for producing an olivine-type phosphate comprises preparing a raw material comprising element A, element M, and phosphorus (P) so that a A:M:P molar ratio may be a:b:1, preliminary calcining the raw material, and mainly calcining the preliminary calcined raw material.

Positive electrode active material, sodium secondary battery, and production method of olivine-type phosphate

The present invention provides a positive electrode active material that can suppress the necessity of performing sieving and is suitable for use in secondary batteries, particularly sodium secondary batteries. Also provided is a powder for a positive electrode active material as a raw material for the positive electrode active material. The powder for a positive electrode active material of the present invention comprises Mn-containing particles. In the cumulative particle size distribution on the volume basis of particles constituting the powder, D50, which is the particle diameter at a 50% cumulation measured from the smallest particle, is in the range of from 0.1 &#x3bc;m to 10 &#x3bc;m, and 90 vol % or more of the particles constituting the powder are in the range of from 0.3 times to 3 times D50. The powder for a positive electrode active material comprises Mn-containing particles, and 90 vol % or more of the particles constituting the powder are in the range of from 0.6 &#x3bc;m to 6 &#x3bc;m. The positive electrode active material is a powdery positive electrode active material obtained by calcining a mixture of the powder for positive electrode active material and a sodium compound. The positive electrode for sodium rechargeable batteries comprises the positive electrode active material.

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Tsukuba, Japan

Masami Makidera