Transition
metal dichalcogenides (TMDCs) are increasingly
studied
for their potential as anode materials in sodium-ion batteries (SIBs)
due to their diverse structural phases. Among them, ReTe2, a low-symmetry distorted 1T-phase with a narrow band gap of 0.2
eV emerges as a particularly promising candidate. This study presents
a comprehensive first-principles analysis to elucidate the electrochemical
reaction mechanism and sodium (Na) storage properties of ReTe2. It is uncovered that ReTe2 undergoes a semiconductor-to-metal
transition upon Na intercalation, which is attributed to significant
charge transfer. The theoretical investigations suggest a maximum
intercalation capacity of x = 1 (NaxReTe2), beyond which the structure evolves into
a Re monomer and a NayTe intermediate
phase. As Na intercalation progresses, tellurium (Te) atoms receive
an increasing number of electrons from Na, which raises the Fermi
level of the system and increases the antibonding contribution in
Re–Te bonds. Consequently, the Re–Te bond strength is
weakened. The intercalation of Na serves dual roles: bridging the
ReTe2 layers and simultaneously injecting carriers into
the lattice, both of which are instrumental in boosting the electrical
conductivity. These insights not only confirm ReTe2 as
a viable anode material for SIBs but also provide a detailed understanding
of the electrochemical behaviors of low-symmetry 1T-phase TMDCs.