High performance lithium-ion batteries using layered 2H-MoTe₂ as anode

The major challenges faced by candidate electrode materials in lithium-ion batteries (LIBs) include their low electronic and ionic conductivities. 2D van der Waals materials with good electronic conductivity and weak interlayer interaction have been intensively studied in the electrochemical processes involving ion migrations. In particular, molybdenum ditelluride (MoTe₂) has emerged as a new material for energy storage applications. Though 2H-MoTe₂ with hexagonal semiconducting phase is expected to facilitate more efficient ion insertion/deinsertion than the monoclinic semi-metallic phase, its application as an anode in LIB has been elusive. Here, 2H-MoTe₂, prepared by a solid-state synthesis route, has been employed as an efficient anode with remarkable Li⁺ storage capacity. The as-prepared 2H-MoTe₂ electrodes exhibit an initial specific capacity of 432 mAh g⁻¹ and retain a high reversible specific capacity of 291 mAh g⁻¹ after 260 cycles at 1.0 A g⁻¹. Further, a full-cell prototype is demonstrated by using 2H-MoTe₂ anode with lithium cobalt oxide cathode, showing a high energy density of 454 Wh kg⁻¹ (based on the MoTe₂ mass) and capacity retention of 80% over 100 cycles. Synchrotron-based in situ X-ray absorption near-edge structures have revealed the unique lithium reaction pathway and storage mechanism, which is supported by density functional theory based calculations.