Preparation of lithium indium oxide via a rheological phase route and its electrochemical characteristics in LiOH and Li2SO4 solutions

Submicrometer-sized lithium indium oxide (LiInO 2 ) powder via a rheological phase method using trilithium citrate tetra hydrate (C 6 H 5 Li 3 O 7 · 4H 2 O) and indium oxide (In 2 O 3 ) has been prepared in this work for the first time. The optimal pyrolyzing temperature range to prepare crystalline LiInO 2 is between 650 and 900 °C, which was confirmed by thermal gravimetric and differential thermogravimetric analysis of the precursor and X-ray diffraction analysis. The pure phase LiInO 2 sample obtained has a uniform particle morphology and submicrosize, which was observed by scanning electron microscopy. The electrochemical studies show that a new pair of cathodic and anodic peaks at 0.23 and 0.38 V (vs. saturated calomel electrode) was obviously observed from the cyclic voltammetry curve of LiInO 2 in 1 M LiOH solution, indicating a battery characteristic of the material in this electrolyte. While in 1 M Li 2 SO 4 solution, the sample presents a supercapacitive characteristic within the same potential range. The reasons for different electrochemical behaviors in these two electrolytes can be attributed to the fact that the reaction of lithium ion insertion/extraction into/out of a LiInO 2 electrode takes place in the bulk material in LiOH electrolyte solution, whereas it takes place on the electrode/ electrolyte interface for Li 2 SO 4 electrolyte case.