Ultrahigh Rate and Ultralong Life Span Sodium Storage of FePS3 Enabled by the Space Confinement Effect of Layered Expanded Graphite

Polar Molecule Intercalation to Weaken P2─S Bonding in MnPS3 Toward Ultrahigh-Capacity Sodium Storage

Layered transition metal trithiophosphates (TMPS3, TM = Mn, Fe, Co, etc.) with high theoretical capacity (>1 300 mAh g-1) are potential anode materials for sodium-ion batteries (SIBs). However, the strong bonding between P2 dimers and S atoms in TMPS3 hinders the efficient alloying reaction between P2 dimers and Na+, resulting in practical capacities much lower than theoretical values. Herein, a polar molecule diisopropylamine (DIPA) is intercalated into MnPS3 for the first time to improve the sodium storage performance effectively. Theoretical calculations show that the electron transfer between DIPA and MnPS3 induces more delocalized S p states and weaker P─S bonds, significantly enhancing the electrochemical activity and sodiation/desodiation reaction kinetics. Moreover, the expanded interlayer spacing from 6.48 to 10.75 Å enables faster Na+ diffusion and more active sites for Na+ adsorption. As expected, the DIPA-MnPS3 exhibits an ultrahigh capacity of 1,023 mAh g-1 at 0.2 A g-1 and excellent cycling performance (≈100% capacity retention after 4 200 cycles at 10 A g-1), far outperforming those metal thiophosphates anodes reported for SIBs. Interestingly, in situ and ex situ characterizations reveal a quasi-topological intercalation mechanism of DIPA-MnPS3. This work provides a novel strategy for the design of high-performance anode materials for SIBs.

Ultralong K0.5Mn0.75PS3 Nanowires Tailored by K-Ion Scissors for Extraordinary Sodium-Ion Storage

1D layered nanowires (NWs) are expected to be excellent electrode materials due to their efficient electron/ion transport and strain/stress relaxation. However, it is a great challenge to synthesize layered NWs by a top-down synthetic route. Herein, ultralong 1D layered K0.5Mn0.75PS3 NWs (length: >100 µm; diameter: ≈300 nm) are synthesized for the first time using "K-ion chemical scissors", whose excellent sodium storage performance originates from the bifunctional structural unit, ingeniously combining the alloying energy storage functional unit (P-P dimer) with the quasi-intercalated functional unit ([MnS3]4- framework). Stress-driven K-ion scissors achieve the rapid transformation of MnPS3 bulk to K0.5Mn0.75PS3 NWs with directed tailoring. Compared to MnPS3, the NWs exhibit enlarged interlayer spacing (9.32 Å), enhanced electronic conductivity (8.17 × 10-5 S m-1 vs 4.47 × 10-10 S m-1), and high ionic conductivity (2.14 mS cm-1). As expected, the NWs demonstrate high capacity (709 mAh g-1 at 0.5 A g-1) and excellent cycling performance (≈100% capacity retention after 2500 cycles at 10 A g-1), ranking among metal thiophosphates. A quasi-topological intercalation mechanism of the NWs is revealed through further characterizations. This work expands the top-down synthesis approach and offers innovative insights for the cost-effective and large-scale fabrication of NWs with outstanding electrochemical performance.

High-Entropy Transition Metal Phosphorus Trichalcogenides for Rapid Sodium Ion Diffusion

High-entropy strategies are regarded as a powerful means to enhance performance in energy storage fields. The improved properties are invariably ascribed to entropy stabilization or synergistic cocktail effect. Therefore, the manifested properties in such multicomponent materials are usually unpredictable. Elucidating the precise correlations between atomic structures and properties remains a challenge in high-entropy materials (HEMs). Herein, atomic-resolution scanning transmission electron microscopy annular dark field (STEM-ADF) imaging and four dimensions (4D)-STEM are combined to directly visualize atomic-scale structural and electric information in high-entropy FeMnNiVZnPS3. Aperiodic stacking is found in FeMnNiVZnPS3 accompanied by high-density strain soliton boundaries (SSBs). Theoretical calculation suggests that the formation of such structures is attributed to the imbalanced stress of distinct metal-sulfur bonds in FeMnNiVZnPS3. Interestingly, the electric field concentrates along the two sides of SSBs and gradually diminishes toward the two-dimensional (2D) plane to generate a unique electric field gradient, strongly promoting the ion-diffusion rate. Accordingly, high-entropy FeMnNiVZnPS3 demonstrates superior ion-diffusion coefficients of 10-9.7-10-8.3 cm2 s-1 and high-rate performance (311.5 mAh g-1 at 30 A g-1). This work provides an alternative way for the atomic-scale understanding and design of sophisticated HEMs, paving the way for property engineering in multi-component materials.

Synthesis of Graphitic Carbon Coated ZnPS3 and its Superior Electrochemical Properties for Lithium and Sodium Ion Storage

Graphitic carbon-coated ZnPS3 is prepared via direct phosphosulfurization and high energy mechanical milling (HEMM) with multiwall carbon nanotubes (MWCNTs) and first introduced as an anode for lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs). The HEMM process with MWCNTs reduces the particle size of as-synthesized ZnPS3 bulk to 100-500 nm and yields the ≈5 nm thick graphitic carbon coated ZnPS3 nanoparticles, which are the nanocomposites of 5 nm sized nanocrystallites embedded in the amorphous matrix. The ZnPS3 electrode undergoes the combined conversion and alloying reactions with Li and Na ions and exhibits high initial discharge and charge capacities in both LIBs and SIBs. The graphitic carbon-coated ZnPS3 electrode exhibits excellent high-rate capability and long-term cyclability. The superior electrochemical properties can be attributed to high electrical conductivity, high Li ion mobility, and high reversibility and structural stability derived from the graphitic carbon-coated nanoparticles. This study demonstrates that the novel graphitic carbon-coated ZnPS3 is a promising anode material for both LIBs and SIBs and the graphitic carbon coating methodology by HEMM is expected to apply to the various metal oxides, sulfides, and phosphides.

Hierarchical Architecture Engineering of Branch-Leaf-Shaped Cobalt Phosphosulfide Quantum Dots: Enabling Multi-Dimensional Ion-Transport Channels for High-Efficiency Sodium Storage

New-fashioned electrode hosts for sodium-ion batteries (SIBs) are elaborately engineered to involve multifunctional active components that can synergistically conquer the critical issues of severe volume deformation and sluggish reaction kinetics of electrodes toward immensely enhanced battery performance. Herein, it is first reported that single-phase CoPS, a new metal phosphosulfide for SIBs, in the form of quantum dots, is successfully introduced into a leaf-shaped conductive carbon nanosheet, which can be further in situ anchored on a 3D interconnected branch-like N-doped carbon nanofiber (N-CNF) to construct a hierarchical branch-leaf-shaped CoPS@C@N-CNF architecture. Both double carbon decorations and ultrafine crystal of the CoPS in-this exquisite architecture hold many significant superiorities, such as favorable train-relaxation, fast interfacial ion-migration, multi-directional migration pathways, and sufficiently exposed Na+ -storage sites. In consequence, the CoPS@C@N-CNF affords remarkable long-cycle durability over 10 000 cycles at 20.0 A g-1 and superior rate capability. Meanwhile, the CoPS@C@N-CNF-based sodium-ion full cell renders the potential proof-of-feasibility for practical applications in consideration of its high durability over a long-term cyclic lifespan with remarkable reversible capacity. Moreover, the phase transformation mechanism of the CoPS@C@N-CNF and fundamental springhead of the enhanced performance are disclosed by in situ X-ray diffraction, ex situ high-resolution TEM, and theoretical calculations.

Metal Phosphorous Chalcogenide: A Promising Material for Advanced Energy Storage Systems

The development of efficient and affordable electrode materials is crucial for clean energy storage systems, which are considered a promising strategy for addressing energy crises and environmental issues. Metal phosphorous chalcogenides (MPX3 ) are a fascinating class of two-dimensional materials with a tunable layered structure and high ion conductivity, making them particularly attractive for energy storage applications. This review article aims to comprehensively summarize the latest research progress on MPX3 materials, with a focus on their preparation methods and modulation strategies. Additionally, the diverse applications of these novel materials in alkali metal ion batteries, metal-air batteries, and all-solid-state batteries are highlighted. Finally, the challenges and opportunities of MPX3 materials are presented to inspire their better potential in energy storage applications. This review provides valuable insights into the promising future of MPX3 materials in clean energy storage systems.

Achieving Ultrahigh-Rate and Low-Temperature Sodium Storage of FePS3 via In Situ Construction of Graphitized Porous N-Doped Carbon

Sodium-ion batteries (SIBs) have become an important supplementation to lithium-ion batteries. Unfortunately, the low capacity and inferior low-temperature performance of traditional hard carbon led to limited energy density and a range of applications of SIBs. Herein, we present high-performance SIBs via embedding FePS₃ in graphitized porous N-doped carbon (FPS/GPNC) using coordination polymerization reaction. Such unique graphitized pores are in situ-constructed by the self-aggregation of Fe nanoparticles with high surface energy at high temperatures, which affords a three-dimensional open channel and a graphitized conductive network for fast transportation of Na⁺ and electrons. Moreover, an ingenious buffer barrier composed of graphitized pores is constructed for FePS₃ to withstand volume fluctuation during cycling. Consequently, a superior capacity of 354.2 mAh g^-1 is delivered even when the rate increases to 50 A g^-1. The impressing cycling lifespan up to 4700 cycles is achieved at 30 A g^-1 with excellent retention of 84.4%. Interestingly, the low-temperature performance (-20 °C) of FePS₃ is explored for the first time, and excellent stability (502.6 mAh g^-1 maintained after 100 cycles at 0.1 A g^-1) is obtained, indicating huge potential of practical application. This work provides insights into designing high-rate, high-capacity, and low-temperature SIBs.