MXenes, represented by Ti3C2T
x
, have been widely studied
in the electrochemical
energy storage fields, including lithium-ion batteries, for their
unique two-dimensional structure, tunable surface chemistry, and excellent
electrical conductivity. Recently, Nb2CT
x
, as a new type of MXene, has attracted more and more attention
due to its high theoretical specific capacity of 542 mAh g–1. However, the preparation of few-layer Nb2CT
x
nanosheets with high-quality remains a challenge,
which limits their research and application. In this work, high-quality
few-layer Nb2CT
x
nanosheets
with a large lateral size and a high conductivity of up to 500 S cm–1 were prepared by a simple HCl-LiF hydrothermal etching
method, which is 2 orders of magnitude higher than that of previously
reported Nb2CT
x
. Furthermore,
from its aqueous ink, the viscosity-tunable organic few-layer Nb2CT
x
ink was prepared by HCl-induced
flocculation and N-methyl-2-pyrrolidone treatment.
When using the organic few-layer Nb2CT
x
ink as an additive-free anode of lithium-ion batteries, it
showed excellent cycling performance with a reversible specific capacity
of 524.0 mAh g–1 after 500 cycles at 0.5 A g–1 and 444.0 mAh g–1 after 5000 cycles
at 1 A g–1. For rate performance, a specific capacity
of 159.8 mAh g–1 was obtained at a high current
density of 5 A g–1, and an excellent capacity retention
rate of about 95.65% was achieved when the current density returned
to 0.5 A g–1. This work presents a simple and scalable
process for the preparation of high-quality Nb2CT
x
and its aqueous/organic ink, which demonstrates
important application potential as electrodes for electrochemical
energy storage devices.