language: en

DOI: 10.1002/zaac.200700541

Synthesis, Structure and Electrochemical Lithium Intercalation Chemistry of Ramsdellite-Type LiCrTiO 4

A. Kuhn, M. Martín, and F. García-Alvarado*
Madrid/Spain,
Departamento de Quı ´mica, Universidad San Pablo-CEU

[Received December 4th, 2007.]

[Dedicated to Professor Joachim Strähle on the Occasion of his 70 th Birthday]

Abstract. LiCrTiO 4 , which crystallizes in the orthorhombic ramsdellite structure, has been obtained by heating spinel LiCrTiO 4 at 1250 °C in air. The refined cell parameters are a 񮽙 4.9835(6) A b 񮽙 9.5095(8) A ånd c 񮽙 2.9282(2) A space group Pbnm, as determined from Rietveld refinement of X-ray powder diffraction data. The intercalation chemistry of LiCrTiO 4 has been investigated. Lithium can be extracted from LiCrTiO 4 due to oxidation of Cr III at rather high potential 4 V. On the other hand, lithium intercalation proceeds readily at 1.5 V due to the reduction of tetravalent titanium. Regarding practical applications, as an electrode for lithium rechargeable batteries, specific capacities of 100 and 120 mAh · g 񮽙1 are developed at 0.1 mA · cm 񮽙2 , respectively. These findings point out that the ramsdellite form of LiCrTiO 4 may be an ambivalent electrode, which can be used either as the positive electrode or the negative electrode of a lithium ion rechargeable battery.

Keywords: Ramsdellite; In situ X-ray diffraction; Spinel-ramsdellite transition; Electrochemcial lithium intercalation; Electrode for lithium batteries Introduction