Solid State Ionics 107 (1998) 123–133 ‘Chimie douce’ synthesis and electrochemical properties of amorphous and crystallized LiNiVO vs. Li 4 a, a a a a b b * F. Orsini , E. Baudrin , S. Denis , L. Dupont , M. Touboul , D. Guyomard ,Y. Piffard , a J.-M. Tarascon a ´ ´ Laboratoire de Reactivite et de Chimie des Solides, UPRES- A 6007 UPJV , 33 rue Saint-Leu, 80039 Amiens Cedex, France b ` IMN, Laboratoire de Chimie des Solides,2 Rue de la Houssiniere, 44072 Nantes Cedex 3, France Received 6 October 1997; accepted 21 October 1997 Abstract Amorphous LiNiVO has been synthesized by a new ‘chimie douce’ method, which consists of a precipitation reaction 4 occurring at a well-defined pH. This new amorphous lithiated vanadate was shown, by means of thermal analyses and X-ray powder diffraction, to progressively crystallize in the spinel-type structure upon increasing the annealing temperature from 2008C to 7008C. Both amorphous and crystallized LiNiVO can reversibly react with 7 Li per formula unit, similar to the 4 compounds synthesized by the classical high temperature route. To understand the chemical transformations occurring during the Li uptake / removal in crystallized LiNiVO , and thereby to throw some light on the origin of the large capacity of those 4 materials, in-situ XRD measurements have been performed. Keywords: LiNiVO ; Lithiated vanadate; Chimie douce; Lithium battery 4 1. Introduction (HT), can reversibly react with about 7 lithium ions per transition metal when discharged to voltages The commercial success of the rechargeable lower than 0.2 V [3], so that specific capacities as lithium-ion technology has prompted research in the high as 800–900 mA h/g, about twice greater than field of transition metal oxides. Besides the common- those of presently used graphite electrodes, could be ly used cathode materials, such as LiMn O , LiCoO achieved. However, this vanadate was shown to 2 4 2 and LiNiO [1,2], other oxides (and particularly become amorphous upon the first electrochemical 2 vanadium oxides) have been identified as good discharge, which must be performed at a slow candidates for anode materials [3]. Among the cycling rate to ensure a proper function of this various vanadates tested, crystallized LiNiVO electrode upon subsequent cycles. A simple way to 4 showed the most promising electrochemical behav- bypass this slow forming step (e.g. amorphization of iour, not as a cathode as previously reported [4,5] but the vanadate) consists in chemically preparing the as an anode. For instance, crystallized LiNiVO , vanadate in its amorphous state. 4 synthesized by the classical high temperature route A ‘chimie douce’ method [6] was previously reported for the synthesis of amorphous RVO (R 5 4 * Corresponding author. In, Fe, Cr, Al, Y) compounds. We experienced that a 0167-2738 / 98 / $19.00  1998 Elsevier Science B.V. All rights reserved. PII S0167-2738(97)00514-6