Li-to-Network Interaction in Electrochemically Lithiated Tin Hydrogen Phosphate

Abstract

Tin hydrogen phosphate (SnHPO4) has been tested as an electrode material in Li cells. It exhibits a high capacity for the first discharge and a capacity of ca. 200 mAh g(Sn)?1 after 25 cycles at 20°C. The Li-to-network interaction during the first discharge has been followed using X-ray diffraction and 7Li, 31P magic-angle spinning nuclear magnetic resonance. The results obtained allow us to propose a Li-reaction mechanism for this phase, based on the formation of Sn and Li3PO4 in the first stage followed by reversible Sn/Li alloying.