Realizing High-Performance Li/Na-Ion Half/Full Batteries via the Synergistic Coupling of Nano-Iron Sulfide and S-doped Graphene

Magnetopyrite Fe1-xS modified with N/S-doped carbon as a synergistic electrocatalyst for lithium-sulfur batteries

Rational design of effective cathode host materials is an effective way to solve the problems of serious shuttle and slow conversion of polysulfides in lithium-sulfur batteries (LSBs). However, the redox reaction of sulfur differs from conventional "Rocking chair" type batteries and involves a cumbersome phase transition process, so a single-component catalyst cannot consistently and steadily enhance the reaction rate throughout the redox process. In this work, a hybrid composed of magnetopyrite Fe1-xS catalyst-modified with N/S-doped porous carbon spheres (Fe1-xS@NSC) is proposed as a novel sulfur host to synergistically promote the adsorption and redox catalysis conversion of polysulfides. In this hybrid, the NSC skeleton provides excellent electrical conductivity and abundant adsorption sites for the physical immobilization of polysulfides; the magnetopyrite Fe1-xS nanoparticles promote the fast conversion reaction from Li2S2 to Li2S, affording strong adsorption and catalytic conversion. The optimal LSB with Fe1-xS@NSC manifests a high initial capacity of 971 mAh g-1 at 0.2 C (1 C = 1675 mAh g-1) and a retention rate of up to 75 % after 100 cycles. This work can provide a new approach for rationalizing the novel transition metal sulfide/porous carbon-based composite hosts with efficient lithium polysulfides (LiPSs) adsorption and catalytic conversion in high-performance lithium-sulfur batteries.

Experimental and Theoretical Insights on Interface Engineered FeS/rGO as Anode for Fast-Charging Lithium- and Sodium-Ion Batteries

Interface engineering facilitates the development of stable energy storage devices that can endure the severe changes encountered during operation. In the context of fast-charging anodes for lithium- and sodium-ion batteries (LIBs and SIBs), the interface needs to promote charge/ion transfer processes, enhance Li-/Na-ion storage capacity, and ensure good reversibility in order to function efficiently at high rates. Herein, a simple synthetic strategy is reported to design interfaces between transition metal sulfides and carbonaceous supports to generate high-performance fast-charging anodes. FeS/rGO nanostructures are synthesized via a simple solid-state annealing method by employing FeOOH/rGO, a metastable precursor, which is annealed at 600 °C in the presence of H₂S gas. Interface engineering between FeS and rGO significantly improved the electrochemical performance, particularly demonstrated by stable capacities at high rates (625 mAh g⁻¹ at 5 A g⁻¹ for LIBs and 708 mAh g⁻¹ at 10 A g⁻¹ for SIBs). The high-rate charge storage is primarily governed by capacitive processes. Density functional theory (DFT) calculations attributed the enhanced performance of the FeS/rGO anode to a lower diffusion energy barrier for Li- and Na-ion diffusion at the interface along with the presence of a built-in electric field at the heterointerface.

The role of graphene aerogels in rechargeable batteries

Energy storage systems, particularly rechargeable batteries, play a crucial role in establishing a sustainable energy infrastructure. Today, researchers focus on improving battery energy density, cycling stability, and rate performance. This involves enhancing existing materials or creating new ones with advanced properties for cathodes and anodes to achieve peak battery performance. Graphene aerogels (GAs) possess extraordinary attributes, including a hierarchical porous and lightweight structure, high electrical conductivity, and robust mechanical stability. These qualities facilitate the uniform distribution of active sites within electrodes, mitigate volume changes during repeated cycling, and enhance overall conductivity. When integrated into batteries, GAs expedite electron/ion transport, offer exceptional structural stability, and deliver outstanding cycling performance. This review offers a comprehensive survey of the advancements in the preparation, functionalization, and modification of GAs in the context of battery research. It explores their application as electrodes and hosts for the dispersion of active material nanoparticles, resulting in the creation of hybrid electrodes for a wide range of rechargeable batteries including lithium-ion batteries (LIBs), Li-metal-air batteries, sodium-ion batteries (SIBs), zinc-ion batteries (AZIBs) and zinc-air batteries (ZABs), aluminum-ion batteries (AIBs) and aluminum-air batteries and other.

Overcoming copper-induced conversion reactions in nickel disulphide anodes for sodium-ion batteries

Employing copper (Cu) as an anode current collector for metal sulphides is perceived as a general strategy to achieve stable cycle performance in sodium-ion batteries, despite the compatibility of the aluminium current collector with sodium at low voltages. The capacity retention is attributed to the formation of copper sulphide with the slow corrosion of the current collector during cycling which is not ideal. Conventional reports on metal sulphides demonstrate excellent electrochemical performances using excessive carbon coatings/additives, reducing the overall energy density of the cells and making it difficult to understand the underlying side reaction with Cu. In this report, the negative influence of the Cu current collector is demonstrated with in-house synthesised, scalable NiS2 nanoparticles without any carbon coating as opposed to previous works on NiS2 anodes. Ex situ TEM and XPS experiments revealed the formation of Cu2S, further to which various current collectors were employed for NiS2 anode to rule out the parasitic reaction and to understand the true performance of the material. Overall, this study proposes the utilisation of carbon-coated aluminium foil (C/Al) as a suitable current collector for high active material content NiS2 anodes and metal sulphides in general with minimal carbon contents as it remains completely inert during the cycling process. Using a C/Al current collector, the NiS2 anode exhibits stable cycling performance for 5000 cycles at 50 A g-1, maintaining a capacity of 238 mA h g-1 with a capacity decay rate of 8.47 × 10-3% per cycle.

Recent Progress on Graphene-Based Nanocomposites for Electrochemical Sodium-Ion Storage

In advancing battery technologies, primary attention is paid to developing and optimizing low-cost electrode materials capable of fast reversible ion insertion and extraction with good cycling ability. Sodium-ion batteries stand out due to their inexpensive price and comparable operating principle to lithium-ion batteries. To achieve this target, various graphene-based nanocomposites fabricate strategies have been proposed to help realize the nanostructured electrode for high electrochemical performance sodium-ion batteries. In this review, the graphene-based nanocomposites were introduced according to the following main categories: graphene surface modification and doping, three-dimensional structured graphene, graphene coated on the surface of active materials, and the intercalation layer stacked graphene. Through one or more of the above strategies, graphene is compounded with active substances to prepare the nanocomposite electrode, which is applied as the anode or cathode to sodium-ion batteries. The recent research progress of graphene-based nanocomposites for SIBs is also summarized in this study based on the above categories, especially for nanocomposite fabricate methods, the structural characteristics of electrodes as well as the influence of graphene on the performance of the SIBs. In addition, the relevant mechanism is also within the scope of this discussion, such as synergistic effect of graphene with active substances, the insertion/deintercalation process of sodium ions in different kinds of nanocomposites, and electrochemical reaction mechanism in the energy storage. At the end of this study, a series of strategies are summarized to address the challenges of graphene-based nanocomposites and several critical research prospects of SIBs that provide insights for future investigations.

Facile synthesis of S-doped LiFePO4@N/S-doped carbon core-shell structured composites for lithium-ion batteries

Heteroatom-doped carbon can significantly improve the electrochemical performance of LiFePO₄cathodes, but it is limited by the complex preparation process and expensive dopants. A self-assembled S-doped LiFePO₄@N/S-doped C core-shell structured composites were synthesized by a convenient solvothermal method are reported. The structure and the electrochemical performance of the composites were characterized. In the S-doped LiFePO₄@N/S-doped C composites, the glucose-derived carbon microspheres were attached by LiFePO₄/C particles to form secondary particles in the core-shell structure. The thioacetamide regulated the morphology of LiFePO₄/C particles and provided N and S atoms to dope the composites. The S-doped LiFePO₄@N/S-doped C composites delivered specific discharge capacities of 157.81 mAh g^-1at 0.1 C and 121.26 mAh g^-1at 5 C, and capacity retention of 99.88% after 100 charge/discharge cycles. The excellent electrochemical performance of the S-doped LiFePO₄@N/S-doped C composites can be attributed to the synergism of thioacetamide and glucose.