2 research outputs found
Carbon Quantum Dots-Derived Carbon Nanosphere Coating on Ti<sub>3</sub>C<sub>2</sub> MXene as a Superior Anode for High-Performance Potassium-Ion Batteries
Potassium-ion batteries (PIBs) are receiving increasing
attention
at present because of their cheap and lithium-like charge/discharge
processes. Nevertheless, the large potassium-ion radius leads to poor
potassium intercalation/depotassium kinetics and unstable structure,
hindering their development. Here, we synthesized a novel carbon quantum
dot-derived carbon nanosphere-encapsulated Ti3C2 MXene (CNS@Ti3C2) composite by polymer pyrolysis,
while carbon nanospheres were derived from carbon quantum dots. The
composites can suppress the layer stacking of Ti3C2 and prevent oxidation, thereby stabilizing the layered structure
of Ti3C2 MXene and improving the cycle life.
Besides, carbon nanospheres can increase the specific surface area
and active sites, and then more potassium ions can enter the electrode
material and boost the reversible capacity. Further, carbon nanospheres
are embedded between the Ti3C2 layers, which
can increase the interlayer spacing, and the potassium ions are more
easily inserted and extracted, thereby improving the potassium storage
power and rate performance. The CNS@Ti3C2 composite
possesses an excellent synergy, resulting in a high reversible capacity
of 229 mAh g–1 at 100 mA g–1 after
200 repeated cycles and a long cycle life of 205 mAh g–1 at 500 mA g–1 after 1000 repeated cycles with
high coulombic efficiency (above 99%). This work offers a novel strategy
to utilize carbon with MXene in energy storage
In Situ Oxygen-Doped Porous Carbon Nanoribbons with Expanded Interlayer Distance for Enhanced Potassium Ion Storage
Carbon
materials have been widely concerned and studied
for potassium-ion
batteries because of abundant resources and low prices. But, the large
radius of potassium ions (1.38 Ã…) restricts its smooth intercalation
and deintercalation into the carbon layer, resulting in poor cycling
stability and rate performance. Herein, in situ oxygen-doped porous
carbon nanoribbons (OPCNBs) have been fabricated by freeze-drying
and pyrolysis of the polymer with enlarged interlayer spacing for
the first time. Due to the porosity and the enlarged interlayer spacing
(0.413 nm) of OPCNB, the potassium ions can be rapidly intercalated
into the carbon layer and smoothly extracted and some of the potassium
ions are adsorbed on the surface active site stemming from the oxygen-doped
group. Further, ex situ TEM showed that the enlarged interlayer spacing
was well preserved during repeated cycling. Therefore, OPCNB exhibits
excellent long cycle stability (180.5 mAh g–1 at
500 mA g–1 after 1000 cycles) and outstanding rate
capability (170 mAh g–1 at 1 A g–1) as a new generation electrode material with development potential
for potassium ions