Rational design of sulfur host materials to synergize the retention and catalysis of lithium polysulfides (LiPSs) is of great significance to accomplish efficient sulfur electrochemistry for lithium–sulfur (Li–S) batteries. Herein, we have elaborately designed Fe single atom decorated porous carbon nanofibers (FeSA-PCNF) through electrospinning to construct self-standing and binder-free cathodes for Li–S batteries. The unique architecture of FeSA-PCNF with interconnected fibrous networks and hierarchical porous structures guarantees rapid charge transfer kinetics as well as abundant active interfaces for LiPS conversions. Moreover, the highly active FeN₄ moieties with surrounding graphitic N dopants embedded in the porous carbon nanofibers ensure strong chemisorption and superior electrocatalytic conversion towards LiPSs. As a consequence, the Li–S batteries assembled with FeSA-PCNF demonstrate superior electrochemical performances with a high rate capability of 791 mA h g⁻¹ at 5C and a low capacity decay rate of 0.048% per cycle after 500 cycles at 2C. More encouragingly, a high areal capacity of 11.1 mA h cm⁻² is achieved after 50 cycles with an ultrahigh sulfur loading of 17 mg cm⁻² and a low electrolyte/sulfur ratio of 5 μl mg⁻¹. This work presents a promising strategy for rational design of self-standing and binder-free cathodes for practically feasible and high-performance Li–S batteries.

The large-scale implementations of lithium iron phosphate (LFP) batteries for energy storage systems have been gaining attention around the world due to their quality of high technological maturity and flexible configuration. Unfortunately, the exponential production of LFP batteries is accompanied by an annual accumulation of spent batteries and a premature consumption of the lithium resource. Recycling souring critical battery materials such as Li₂CO₃ is essential to reduce the supply chain risk and achieve net carbon neutrality goals. During the recovery of Li₂CO₃, impurity removal is the most crucial step in the hydrometallurgy process of spent LiFePO₄, which determines the purity of Li₂CO₃. By investigating and comparing the results of impurity elimination from the purified Li⁺-containing liquids with strong and weak alkalis under identical pH conditions, respectively, a strategy based on an alkali mixture has been proposed. The purified Li⁺-containing liquid was, thereafter, concentrated and sodium carbonate was added in order to precipitate Li₂CO₃. As a result, a high purity Li₂CO₃ (99.51%) of battery grade was obtained. LiFePO₄ prepared with the recovered Li₂CO₃ and FePO₄ as raw materials also displayed a comparative high capacity and stable cycle performance to the commercial product and further verified the electrochemical activity of the recovered materials.

The deployment of Li–S batteries in the commercial sector faces obstacles due to their low electrical conductivity, slow redox reactions, quick fading of capacity, and reduced coulombic efficiency. These issues stem from the “shuttle effect” associated with lithium polysulfides (LiPSs). In this work, a haystack-like CeO₂ derived from a cerium-based metal-organic framework (Ce-MOF) is obtained for the modification of a polypropylene separator. The carbon framework and CeO₂ coexist in this haystack-like structure and contribute to a synergistic effect on the restriction of LiPSs shuttling. The carbon network enhances electron transfer in the conversion of LiPSs, improving the rate performance of the battery. Moreover, CeO₂ enhances the redox kinetics of LiPSs, effectively reducing the “shuttle effect” in Li–S batteries. The Li–S battery with the optimized CeO₂ modified separator shows an initial discharge capacity of 870.7 mAh/g at 2 C, maintaining excellent capacity over 500 cycles. This research offers insights into designing functional separators to mitigate the “shuttle effect” in Li–S batteries.

Aqueous zinc-ion batteries (ZIBs) are an appealing rechargeable battery technology for next-generation energy storage devices, known for their low cost and high safety. Among the promising cathode materials used for aqueous ZIBs, anthraquinone (AQ) stands out due to its high theoretical specific capacity, low cost, and environmental friendliness. In this study, we investigate the cyclic stability of AQ in aqueous ZIBs. We demonstrate that AQ exhibits a good capacity retention at a high current density even after 1000 charge–discharge cycles, while more obvious capacity fading is observed at a low current density. Density functional theory calculations reveal that the mechanism of the rapid capacity fading under a low current density is due to the significant structural deformation of AQ crystal during Zn insertion into the AQ bulk. Furthermore, the energy barrier of Zn ions that diffuse into the AQ bulk is much higher than the diffuse on the AQ surface, leading to an irreversible Zn insertion. However, under a high current density, Zn ions prefer to adsorb and diffuse on the AQ surface without bulk insertion and structural deformation, rending a higher cycling stability. These insights into the factors influencing the cycling stability of AQ-based electrodes offer a guidance to improve their performance for practical applications.