Electrochemical activity of Li2FeTiO4 and Li2MnTiO4 as potential active materials for Li ion batteries: A comparison with Li2NiTiO4

We demonstrate, for the first time, a considerable electrochemical activity of two members of lithium transition element titanates: Li2FeTiO4 and Li2MnTiO4. Both materials consist of 10–20 nm particles embedded in a conductive carbon coating. We show that not the coating but the small particle size is decisive for materials’ activity. Li2FeTiO4 shows a stable reversible capacity of up to 123 mA hg−1 at C/20 and 60 °C which is 83% of the theoretical value for exchange of 1 electron (148 mA hg−1). Li2MnTiO4 could only be prepared in a nanosized form that contained about 30% of impurities. The capacity of the whole material (including impurities) is comparable to that of Li2FeTiO4 but the cycling stability is much poorer. In contrast to the Fe and Mn analogues, the third member of the titanate family, Li2NiTiO4, shows a good electrochemistry even when the particle size is much larger (about 100 nm). During initial cycles at C/10 and 60 °C, exchange of more than 1 electron per compound formula has been observed. The cycling stability at high temperatures, however, is poor.