2 research outputs found
Offset Initial Sodium Loss To Improve Coulombic Efficiency and Stability of Sodium Dual-Ion Batteries
Sodium
dual-ion batteries (NDIBs) are attracting extensive attention recently
because of their low cost and abundant sodium resources. However,
the low capacity of the carbonaceous anode would reduce the energy
density, and the formation of the solid-electrolyte interphase (SEI)
in the anode during the initial cycles will lead to large amount
consumption of Na<sup>+</sup> in the electrolyte, which results in
low Coulombic efficiency and inferior stability of the NDIBs. To address
these issues, a phosphorus-doped soft carbon (P-SC) anode combined
with a presodiation process is developed to enhance the performance
of the NDIBs. The phosphorus atom doping could enhance the electric
conductivity and further improve the sodium storage property. On the
other hand, an SEI could preform in the anode during the presodiation
process; thus the anode has no need to consume large amounts of Na<sup>+</sup> to form the SEI during the cycling of the NDIBs. Consequently,
the NDIBs with P-SC anode after the presodiation process exhibit high
Coulombic efficiency (over 90%) and long cycle stability (81 mA h
g<sup>–1</sup> at 1000 mA g<sup>–1</sup> after 900 cycles
with capacity retention of 81.8%), far more superior to the unsodiated
NDIBs. This work may provide guidance for developing high performance
NDIBs in the future
Construction of Uniform Cobalt-Based Nanoshells and Its Potential for Improving Li-Ion Battery Performance
Surface
cobalt doping is an effective and economic way to improve the electrochemical
performance of cathode materials. Herein, by tuning the precipitation
kinetics of Co<sup>2+</sup>, we demonstrate an aqueous-based protocol
to grow uniform basic cobaltous carbonate coating layer onto different
substrates, and the thickness of the coating layer can be adjusted
precisely in nanometer accuracy. Accordingly, by sintering the cobalt-coated
LiNi<sub>0.5</sub>Mn<sub>1.5</sub>O<sub>4</sub> cathode materials,
an epitaxial cobalt-doped surface layer will be formed, which will
act as a protective layer without hindering charge transfer. Consequently,
improved battery performance is obtained because of the suppression
of interfacial degradation