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111 sitzr measurements of the Ni and Co K-edge XAFS spectra of Li1.~Ni02 and Lil.,CoOz as a function of x were successfully carried out for the first time using an electrocl~emical ceii. It is observed that a local Jahn-Teller distortion of the Ni06 octahedron in LiN102 was reduced with deintercalation of Li which caused oxidatiou of the Jahn-Teller d7 ~i~* ion to do Ni4+i011. A substitution of Co for Ni in LiNiO? also reduced the local distortion of the NiO, octahedron. XANES spectra of LiNi02 shifted to higher energy side with increasing x while an abrupt shape change was observed in the XANES spectra of Li,.,CoOl correspollding to phase trausition.