The shuttle effect induced by soluble lithium polysulfides (LiPSs) is known as one of the crucial issues that limit the practical applications of lithium-sulfur (Li-S) batteries. Herein, a titanium dioxide nanoparticle embedded in nitrogen-doped porous carbon nanofiber (TiO₂@NCNF) composite is constructed via an interface-induced polymerization strategy to serve as an ideal sulfur host. Under the protection of the nanofiber walls, the uniformly dispersed TiO₂ nanocrystalline can act as capturing centers to constantly immobilize LiPSs towards durable sulfur chemistry. Besides, the mesoporous microstructure in the fibrous framework endows the TiO₂@NCNF host with strong physical reservation for sulfur and LiPSs, sufficient pathways for electron/ion transfer, and excellent endurance for volume change. As expected, the sulfur-loaded TiO₂@NCNF composite electrode presents a fabulous rate performance and long cycle lifespan (capacity fading rate of 0.062% per cycle over 500 cycles) at 2.0 C. Furthermore, the assembled Li-S batteries harvest superb areal capacity and cycling stability even under high sulfur loading and lean electrolyte conditions.

Lithium (Li) metal is regarded as the best anode material for lithium metal batteries (LMBs) due to its high theoretical specific capacity and low redox potential. However, the notorious dendrites growth and extreme instability of the solid electrolyte interphase (SEI) layers have severely retarded the commercialization process of LMBs. Herein, a double-layered polymer/alloy composite artificial SEI composed of a robust poly(1,3-dioxolane) (PDOL) protective layer, Sn and LiCl nanoparticles, denoted as PDOL@Sn-LiCl, is fabricated by the combination of in-situ substitution and polymerization processes on the surface of Li metal anode. The lithiophilic Sn-LiCl multiphase can supply plenty of Li-ion transport channels, contributing to the homogeneous nucleation and dense accumulation of Li metal. The mechanically tough PDOL layer can maintain the stability and compact structure of the inorganic layer in the long-term cycling, and suppress the volume fluctuation and dendrites formation of the Li metal anode. As a result, the symmetrical cell under the double-layered artificial SEI protection shows excellent cycling stability of 300 h at 5.0 mA·cm⁻² for 1 mAh·cm⁻². Notably, the Li||LiFePO₄ full cell also exhibits enhanced capacity retention of 150.1 mAh·g⁻¹ after 600 cycles at 1.0 C. Additionally, the protected Li foil can effectively resist the air and water corrosion, signifying the safe operation of Li metal in practical applications. This present finding proposed a different tactic to achieve safe and dendrite-free Li metal anodes with excellent cycling stability.

Despite the high theoretical specific capacity, the main challenges of rechargeable lithium-sulfur (Li-S) batteries, including the unceasing shuttle of soluble lithium polysulfides (LiPSs) and severe Li corrosion, seriously hinder their commercial and practical applications. Herein, a bifunctional polyvinyl alcohol/poly(lithium acrylate) (C-PVA/PAA-Li) composite nanofiber separator is developed to address the main challenges in Li-S batteries by simultaneously allowing rapid lithium ion transport and ionic shielding of polysulfides. The C-PVA/PAA-Li composite nanofiber membrane is prepared via the facile electrospinning strategy, followed by thermal crosslinking and in-situ lithiation processes. Differing from the conventional Celgard-based coating methods accompanied by impaired lithium ion transport efficiency, the C-PVA/PAA-Li composite nanofiber membrane possesses well-developed porous structures and high ionic conductivity, thus synergistically reducing the charge transfer resistance and inhibiting the growth of lithium dendrites. The resulting Li-S batteries exhibit an ultra-low fading rate of 0.08% per cycle after 400 cycles at 0.2 C, and a capacity of 633 mA·h·g^-1 at a high current density of 3 C. This study presents an inspiring and promising strategy to fabricate emerging dual-functional separators, which paves the pathway for the practical implementation of ultra-stable and reliable Li-S battery systems.