Reversibility of the electrochemical lithium insertion in “Cr 3O 8”—comparison with LiCr 3O 8

Abstract

Electrochemical lithium insertion in Cr 3O 8 at room temperature and at 125°C is compared to that of LiCr 3O 8. The capacity is ca 1.4 Li/Cr in Cr 8O 21 at both temperatures by discharge to 2 V vs Li. During recharge a structural change takes place. By discharge to 1.5 V, additional 0.4 Li/Cr (1.8 in total) is accepted by the oxide. At high temperature, it is difficult to extract the inserted lithium. Only 2–3 cycles are obtained. At room temperature the system appears to be fairly insensitive to overdischarge. By discharge of the system Li/LiCr 3O 8, ca 1.7 Li/Cr is accepted by both temperatures and at potentials above 1.5 V vs Li. The reaction involves major structural changes as insertion of even small amounts of lithium leads to irreversible structural breakdown. Comparison of the lithium insertion of the two compounds, indicates that the reaction products of the insertion reactions are similar in nature after a number of cycles.