Trace ethanol as an efficient electrolyte additive to reduce the activation voltage of the Li2S cathode in lithium-ion-sulfur batteries.

Trace ethanol is applied as a cheap and effective electrolyte additive for reducing the activation voltage of Li2S cathodes in lithium-ion-sulfur batteries. Because Li2S can dissolve in ethanol, the solid-solid phase reaction in the first stage of the activation process converts into a liquid-solid phase reaction, which expedites the transport of electrons and lithium ions and reduces the activation voltage of Li2S. This strategy can be extended to other solvents that can dissolve Li2S.

A new high-capacity and safe energy storage system: lithium-ion sulfur batteries.

Lithium-ion sulfur batteries as a new energy storage system with high capacity and enhanced safety have been emphasized, and their development has been summarized in this review. The lithium-ion sulfur battery applies elemental sulfur or lithium sulfide as the cathode and lithium-metal-free materials as the anode, which can be divided into two main types. One is anode-type, where elemental sulfur is applied as the cathode, and the anode provides lithium ions. The other one is cathode-type, where lithium sulfide as the cathode provides lithium ions, and lithium-metal-free materials (e.g., graphite, silicon/carbon) function as the anode. Recently, some new lithium-ion sulfur battery systems have also been proposed, and are discussed in this review as well. The lithium-ion sulfur batteries not only maintain the advantage of high energy density because of the high capacities of sulfur and lithium sulfide, but also exhibit the improved safety of the batteries due to a non-lithium-metal in the anode. This review paper aims to track the recent progress in the development of lithium-ion sulfur batteries and summarize the challenges and the approaches for improving their electrochemical performances, including the lithiation methods to prepare lithium-metal-free anodes in anode-type lithium-ion sulfur batteries and the lithium sulfide cathode modification approaches in cathode-type lithium-ion sulfur batteries. Furthermore, the challenges and perspectives for future research and commercial applications have also been enumerated.

Ternary confined-functional sulfur composite with a host-sulfur-container architecture for lithium/sulfur batteries.

In this work, a ternary confined-functional sulfur composite with a Host-Sulfur-Container structure is designed and synthesized for high performance lithium sulfur batteries. The host in this unique architecture is porous carbon, which contains interconnected macropore tunnels and meso/micropores on the macropore tunnel walls. These hierarchical pores exhibit a synergistic effect to adsorb sulfur in their spaces and provide more nucleation sites to direct the uniform coating of sulfur. Moreover, the interconnected porous structure can facilitate electron transfer and also ensure high sulfur utilization. Furthermore, the poly(3,4-ethylenedioxythiophene) layer container improves the conductivity of the electrode, prevents the diffusion of dissolved polysulfide, and prevents volume expansion during the charge-discharge processes. As a result, the electrode with the poly(3,4-ethylenedioxythiophene)/sulfur/porous carbon composite and Host-Sulfur-Container architecture maintains a reversible capacity of 831.9 mA h g-1 after 200 cycles at a current density of 0.5 C and presents long-term cycling stability with 0.088% capacity decay per cycle over 500 cycles at 1 C. This indicates that the prepared Host-Sulfur-Container composite is a promising cathode material for lithium-sulfur batteries, and its hierarchical tunnel pore carbon host with meso/micropores inside shows great potential in the energy storage field.