Novel Strategy for the Formulation of High-Energy-Density Cathodes via Porous Carbon for Li-S Batteries.

Porous carbon is considered an attractive host material for high-energy sulfur electrodes. This study concerns the design of a porous carbon-based sulfur electrode for the formulation of high-energy Li-S batteries. The porous carbon is impregnated with up to 80 vol.% of sulfur and a reduction in both the conductive agent and binder content. Therefore, less solvent can be used during slurry casting to inhibit crack formation following electrode drying. In addition, the utilization of two distinct electrically conducting networks enables reduced battery polarization, resulting in a battery with a capacity of 690 mAh g-1 (even after 100 cycles). Finally, pouch cells are prepared to characterize the practical performance of the optimized cathode. This yields a capacity of 741 mAh and a cathode energy density of 1001 Wh kg-1 . These findings are expected to guide the further development of high-energy-density cathode materials for Li-S batteries.

Development of titanium 3D mesh interlayer for enhancing the electrochemical performance of zinc-bromine flow battery.

Zinc dendrite growth negatively affects zinc-bromine flow battery (ZBB) performance by causing membrane damage, inducing self-discharge. Herein, in a ZBB, a conventional polymer mesh was replaced with a titanium-based mesh interlayer; this provided additional abundant active sites for the Zn2+/Zn redox reaction and well-developed electrolyte flow channels, which resulted in improved reaction kinetics and suppressed Zn dendrite growth. Compared with a ZBB cell comprising a conventional polymer mesh and a carbon-based electrode, the ZBB cell using the titanium mesh interlayer and a carbon-based electrode showed significantly reduced frequency of the refreshing process, which occurs at regular cycling intervals during practical use for removing residual zinc dendrites in ZBB; also, the average energy efficiency at a current density of 40 mA cm-2 increased by 38.5%. Moreover, the modified ZBB cell exhibited higher energy efficiency at a high current density of 80 mA cm-2, which is an improvement of 14.7% than in case of the contemporary polymer mesh. Consequently, this study can provide helpful insights for new anode side structures including spacer mesh for developing high-performance ZBBs.

Robust cycling of Li-O2 batteries through the synergistic effect of blended electrolytes.

Despite their exceptionally large specific capacities, the use of Li-O2 batteries has been limited because of their poor cycle lives, which originates from irreversible reaction processes during each cycle. Recent investigations have found that electrolyte decomposition is one of the most critical reasons for capacity decay. Herein, we report that a blended electrolyte, consisting of a carbonate solvent and an ionic liquid, improves the cycle lives of Li-O2 batteries remarkably through a synergistic effect from both components. Both electrolyte components perform complementary functions to each other: The ionic liquid suppresses the decomposition of the carbonate solvent, and the carbonate solvent resolves the poor ionic conductivity of the ionic liquid. This study confirms the importance and opportunities for the use of electrolytes in Li-O2 batteries.

Electrospun three-dimensional mesoporous silicon nanofibers as an anode material for high-performance lithium secondary batteries.

Mesoporous silicon nanofibers (m-SiNFs) have been fabricated using a simple and scalable method via electrospinning and reduction with magnesium. The prepared m-SiNFs have a unique structure in which clusters of the primary Si nanoparticles interconnect to form a secondary three-dimensional mesoporous structure. Although only a few nanosized primary Si particles lead to faster electronic and Li(+) ion diffusion compared to tens of nanosized Si, the secondary nanofiber structure (a few micrometers in length) results in the uniform distribution of the nanoparticles, allowing for the easy fabrication of electrodes. Moreover, these m-SiNFs exhibit impressive electrochemical characteristics when used as the anode materials in lithium ion batteries (LIBs). These include a high reversible capacity of 2846.7 mAh g(-1) at a current density of 0.1 A g(-1), a stable capacity retention of 89.4% at a 1 C rate (2 A g(-1)) for 100 cycles, and a rate capability of 1214.0 mAh g(-1) (at 18 C rate for a discharge time of ∼3 min).