Behavior of some potassium tungstates in the course of electrochemical lithium insertion

Electrochemical lithium insertion has been studied in K2WO4, K2W3O10 and K2W4O13 through galvanostatic intermittent titration technique. We have monitored structural changes in the host matrix as lithium insertion proceeds through in situ X-ray diffraction experiments. In particular, K2WO4 showed to be unable to insert lithium in appreciable amounts. The maximum amount of lithium inserted in each oxide leads to specific capacities of 18 Ah/kg for K2WO4, 220 Ah/kg for K2W3O10 and 265 Ah/kg for K2W4O13. Nevertheless, due to irreversible structural transformations in the host matrix, such capacities were dramatically lost after the first cycle.