Abstract
Molybdenum disulfide (MoS2) is one of the promising electrochemical energy storage materials among the
recently explored 2D materials beyond the extensively studied graphene sheets. However, MoS2 in the form
of quantum sheets (QSs) has not yet been examined for use in energy storage devices (batteries and
supercapacitors). Here, we demonstrate the superior electrochemical charge-storage properties of
exfoliated MoS2 QSs (with lateral size in the range of 5 to 10 nm) for the first time. A salt-assisted ball
milling process was used to prepare MoS2 QSs in gram scale that leads to size confinement in both
lateral and vertical orientations. The electrochemical analysis of MoS2 QSs indicated their superior
capacitive properties compared to the bulk MoS2, which originates from the combination of quantum
capacitance and electrochemical capacitance. The device specific properties of MoS2 QSs were studied
by constructing a flexible symmetric supercapacitor (SSC) that demonstrated a high device capacitance
(162 F g1), energy density (14.4 Wh kg1), good rate capability, and long cycle life. The energy storage
performance metrics of MoS2 QSs based SSC device were superior compared to the state-of-art MoS2
based supercapacitors. Furthermore, a solar-driven wireless charging power system comprising the
fabricated MoS2 QSs-based SSC as an energy storage device is illustrated in the view of expanding its
utility towards practical applications.
