Abstract
AbstractLithium–sulfur batteries (Li–S) have become a viable alternative to future energy storage devices. The electrochemical reaction based on lithium and sulfur promises an extraordinary theoretical energy density, which is far higher than current commercialized Li‐ion batteries. However, the principal disadvantage impeding the success of Li–S batteries lies in the severe leakage and migration of soluble lithium polysulfide intermediates out of cathodes upon cycling. The loss of active sulfur species incurs significant capacity decay and poor battery lifespans. Considerable efforts have been devoted to developing various sulfur host materials that can effectively anchor lithium polysulfides. Herein, a comprehensive review is presented of recent advances in sulfur host materials. On the basis of the electrochemistry of Li–S batteries, the strategies for anchoring polysulfides are systematically categorized into physical confinement and chemical bonding. The structural merits of various sulfur host materials are highlighted, and the interaction mechanisms with sulfur species are discussed in detail, which provides valuable insights into the rational design and engineering of advanced sulfur host materials facilitating the commercialization of Li–S batteries. Future challenges and promising research prospects for sulfur host materials are proposed at the end of the review.
Highlights
Introduction energy storage devicesThe electrochemical reaction based on lithium and sulfur promises an extraordinary theoretical energy density, which is far higher than current commercialized Li-ion batteries
The as-prepared MoS2@HCS host materials revealed some interesting characteristics: 1) the hollow carbon bubbles provided many voids for sulfur loading and alleviated the electrode swelling upon lithiation; 2) highly conductive HCS ensured the charge transport, improving the sulfur utilization; 3) the polar MoS2 dispersed at HCS inhibited the polysulfide shuttling process and prolonged the electrodes cycle life by effective polysulfide adsorption; 4) the introduced MoS2 accelerated the electrochemical redox kinetics
With regard to physical confinement, sulfur hosts with porous and layered or shelled electrode structures can serve as physical barriers to successfully confine polysulfides upon cycling
Summary
In 2014, he has been appointed as International Adjunct Faculty at Amrita University, Coimbatore (India), as group leader at Forschungszentrum Jülich (Germany), and in 2018 as honorary professor at University of Technology Sydney This two-electron (per S atom) redox process offers a considerable theoretical capacity of sulfur cathodes, which is almost ten times higher than that of the present commercial Li-ion cathode materials.[33] In comparison with conventional metal oxide cathode materials undergoing insertion reactions with lithium, sulfur involves numerous structural changes and. A small voltage peak emerges at the end of this discharge stage, which results from a higher overpotential caused by the high electrolyte viscosity due to polysulfide dissolution.[37] Stages I and II contribute to the one fourth (419 mAh g−1) of the overall theoretical specific capacity, corresponding to the acceptance of 0.5 electron per sulfur atom.[38]. Various strategies to effectively anchor polysulfides within the cathode have proven to be successful for the design of highperformance Li–S batteries
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