posted on 2023-12-05, 22:00authored byHamid Mollania, Chaoqi Zhang, Ruifeng Du, Xueqiang Qi, Junshan Li, Sharona Horta, Maria Ibañez, Caroline Keller, Pascale Chenevier, Majid Oloomi-Buygi, Andreu Cabot
Lithium–sulfur
batteries are regarded as an advantageous
option for meeting the growing demand for high-energy-density storage,
but their commercialization relies on solving the current limitations
of both sulfur cathodes and lithium metal anodes. In this scenario,
the implementation of lithium sulfide (Li2S) cathodes compatible
with alternative anode materials such as silicon has the potential
to alleviate the safety concerns associated with lithium metal. In
this direction, here, we report a sulfur cathode based on Li2S nanocrystals grown on a catalytic host consisting of CoFeP nanoparticles
supported on tubular carbon nitride. Nanosized Li2S is
incorporated into the host by a scalable liquid infiltration–evaporation
method. Theoretical calculations and experimental results demonstrate
that the CoFeP–CN composite can boost the polysulfide adsorption/conversion
reaction kinetics and strongly reduce the initial overpotential activation
barrier by stretching the Li–S bonds of Li2S. Besides,
the ultrasmall size of the Li2S particles in the Li2S–CoFeP–CN composite cathode facilitates the
initial activation. Overall, the Li2S–CoFeP–CN
electrodes exhibit a low activation barrier of 2.56 V, a high initial
capacity of 991 mA h gLi2S–1, and outstanding cyclability with a small fading rate of 0.029%
per cycle over 800 cycles. Moreover, Si/Li2S full cells
are assembled using the nanostructured Li2S–CoFeP–CN
cathode and a prelithiated anode based on graphite-supported silicon
nanowires. These Si/Li2S cells demonstrate high initial
discharge capacities above 900 mA h gLi2S–1 and good cyclability with a capacity fading rate
of 0.28% per cycle over 150 cycles.