Pyroxene LiVSi_2O_6 as an electrode material for Li-ion batteries

摘要

Lithium vanadium metasilicate (LiVSi_2O_6) with pyroxene structure has been exploited as an electrode material for Li-ion batteries. Galvanostatic charge and discharge tests show that LiVSi_2O_6 is able to deliver a capacity of 85 mAhg~(-1) at 30℃,andahigh capacity of 181 mAhg~(-1) at 60 ℃. The high capacity is believed to be due to the reactions of V~(3+)/V~(4+) and V~(2+)/V~(3+) redox couples, accompanied by the excess 0.42 Li~+ insertion into the lattice forming a Li-rich phase Li_(1.42)VSi_2O_6. High-energy synchrotron XRD combined with the Rietveld refinement analysis confirms that the electrochemical delithiation-lithiation reaction proceeds by a single phase redox mechanism with an overall volume variation of 1.9% between LiVSi_2O_6 and its delithiated state, indicating a very stable framework of LiVSi_2O_6 for Li~+ ions extraction-insertion.