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Designed Formulation of Se-Impregnated N‑Containing Hollow Core Mesoporous Shell Carbon Spheres: Multifunctional Potential Cathode for Li–Se and Na–Se Batteries
journal contribution
posted on 2017-07-18, 00:00 authored by Balakumar Kalimuthu, Kalaiselvi NallathambyNitrogen-containing
carbon spheres with hollow core and mesoporous shell (NHCS), capable
of confining Se at levels as high as 72 wt % has been demonstrated
to exhibit appreciable electrochemical behavior with 52 and 61 wt
% Se loading. In particular, 52 wt % Se confined NHCS cathode exhibits
265 mAh/g at 10C rate and retains 75% of initial capacity at 2C rate
up to 10 000 cycles with an insignificant decay of 0.0025%
per cycle, which is an ever first report on the extended cycle life
of Li–Se batteries. Due to the negligible difference found
between the transport kinetics of Se and that of Li2Se,
irrespective of the cycling rate, 52 wt % Se @ NHCS performs better
at high rates. Furthermore, capacity is governed by the extent of
utilization of confined Se and cycle life by the extent of mitigation
of volume expansion. Accordingly, rate capability studies recommend
52 wt % Se loaded cathode above 2C rate and 61 wt % Se loading up
to 2C rate. Furthermore, NHCS/Se-52 cathode demonstrates suitability
for Na–Se batteries by exhibiting 339 and 219 mAh/g of capacity
at rates of C/5 and 2C rates, respectively. NHCS with select Se concentration
could thus be exploited for multifunctional cathode behavior in Li–Se
and Na–Se systems.