LAYERED DOUBLE HYDROXIDE AND METHOD FOR PRODUCTION THEREOF, AND AIR ELECTRODE AND METAL-AIR SECONDARY BATTERY THAT USE SAID LAYERED DOUBLE HYDROXIDE

A layered double hydroxide is represented by the following formula (I): NiFeVCo(OH)A·mHO . . . (I). In one embodiment, in the formula (I), (x+y+z) is from 0.2 to 0.5, “x” represents more than 0 and 0.3 or less, “y” represents from 0.04 to 0.49, and “z” represents more than 0 and 0.2 or less.