On really stoichiometric LiCoO2
نویسندگان
چکیده
The Li NMR T1 relaxation time is shown to be a very severe criterion for determining the stoichiometry of LiCoO2. When Co3O4 containing minimum impurity level of paramagnetic ions such as Fe or Ni is used as starting material (together with Li2CO3), a T1 value as long as 18 s is obtained but this requires a rather long thermal treatment for complete elimination of excess Li. Such highly stoichiometric Li1CoO2 exhibits a rather early insulator to metal transition upon Li deintercalation. Magnetic susceptibility and specific heat capacity investigations show the exclusive presence of diamagnetic LS Co. Introduction LiCoO2 has been the subject of quite a lot of investigations, as reviewed by Antolini (1). Being still the most common positive electrode material for Li-ion batteries, it is quite significant that some aspects of its structure or properties are still under debate. Close similarity of its structure with the Na based cobaltites that presently receive considerable attention for their thermoelectric behaviour (2 , 3) also makes LiCoO2 a material of particular interest. 1 Corresponding author, [email protected] 2 Electrochemical society active member 1 ha l-0 03 24 04 2, v er si on 1 23 S ep 2 00 8 Author manuscript, published in "Electrochemical and Solid-State Letters 11, 11 (2008) A179-A182" DOI : 10.1149/1.2968953
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