Flexible and binder free electrode with d-p band center manipulated MoTe2 nanosheets towards high energy Lithium–Sulfur batteries

Abstract

The practical usage of lithium sulfur (Li–S) batteries has been hampered by the severely sluggish conversion kinetics of lithium polysulfides (LiPSs) and the overused of binders and electrolyte, resulting in energy density decreased dramatically. In this work, as a catalyst for LiPSs conversion of great potential, the poor catalytic performance of MoTe2 is revealed to be the wide gap of d-p band center, which hinders the electron exchange of interfacial redox dynamics. Accordingly, the binder-free cathodes are fabricated by recrystallizing sulfur on phosphorus-doped MoTe2 decorated carbon cloth (P-MoTe2/CC) to boost Li–S battery performance. The electron deficient P in MoTe2 lifts the d-band center of P-MoTe2 to Fermi level and narrows the gap of d-p band center when it interacts with LiPSs, which significantly increases the catalytic activity of MoTe2 towards both LiPSs oxidation and reduction. With these features, the P-MoTe2/CC cathodes therefore offers a high initial discharge capacity of 1480.55 mAh g−1 and a low capacity decay of 0.42 % per cycle. Even at high sulfur loading and lean electrolyte of 4.3 (E/S ratio), the Li–S pouch cell can also perform an outstanding cycling stability and reach a high energy density of about 400 Wh kg−1.