Metal-Organic Frameworks-Derived Co2P@N-C@rGO with Dual Protection Layers for Improved Sodium Storage

Engineering CoP Alloy Foil to a Well-Designed Integrated Electrode Toward High-Performance Electrochemical Energy Storage

Nanostructured integrated electrodes with binder-free design show great potential to solve the ever-growing problems faced by currently commercial lithium-ion batteries such as insufficient power and energy densities. However, there are still many challenging problems limiting practical application of this emerging technology, in particular complex manufacturing process, high fabrication cost, and low loading mass of active material. Different from existing fabrication strategies, here using a CoP alloy foil as a precursor  a simple neutral salt solution-mediated electrochemical dealloying method to well address the above issues is demonstrated. The resultant freestanding mesoporous np-Co(OH)_x /Co₂ P product possesses not only active compositions of high specific capacity and large electrode packing density (>3.0 g cm^-3 ) to meet practical capacity requirements, high-conductivity and well-developed nanoporous framework to achieve simultaneously fast ion and electron transfer, but also interconnected ligaments and suitable free space to ensure strong structural stability. Its comprehensively excellent electrochemical energy storage (EES) performances in both lithium/sodium-ion batteries and lithium-ion capacitors can further illustrate the effectiveness of the integrated electrode preparation strategy, such as remarkable reversible specific capacities/capacitances, dominated pseudo-capacitive EES mechanism, and ultra-long cycling life. This study provides new insights into preparation and design of high-performance integrated electrodes for practical applications.

In Situ Fabrication of Porous Cox P Hierarchical Nanostructures on Carbon Fiber Cloth with Exceptional Performance for Sodium Storage

Superior high-rate performance and ultralong cycling life have been constantly pursued for rechargeable sodium-ion batteries (SIBs). In this work, a facile strategy is employed to successfully synthesize porous Co_x P hierarchical nanostructures supported on a flexible carbon fiber cloth (Co_x P@CFC), constructing a robust architecture of ordered nanoarrays. Via such a unique design, porous and bare structures can thoroughly expose the electroactive surfaces to the electrolyte, which is favorable for ultrafast sodium-ion storage. In addition, the CFC provides an interconnected 3D conductive network to ensure firm electrical connection of the electrode materials. Besides the inherent flexibility of the CFC, the integration of the hierarchical structures of Co_x P with the CFC, as well as the strong synergistic effect between them, effectively help to buffer the mechanical stress caused by repeated sodiation/desodiation, thereby guaranteeing the structural integrity of the overall electrode. Consequently, Co_x P@CFC as an anode shows a record-high capacity of 279 mAh g^-1 at 5.0 A g^-1 with almost no capacity attenuation after 9000 cycles.

Phosphorus/Phosphide-Based Materials for Alkali Metal-Ion Batteries

Phosphorus- and phosphide-based materials with remarkable physicochemical properties and low costs have attracted significant attention as the anodes of alkali metal (e.g., Li, Na, K, Mg, Ca)-ion batteries (AIBs). However, the low electrical conductivity and large volume expansion of these materials during electrochemical reactions inhibit their practical applications. To solve these problems, various promising solutions have been explored and utilized. In this review, the recent progress in AIBs using phosphorus- and phosphide-based materials is summarized. Thereafter, the in-depth working principles of diverse AIBs are discussed and predicted. Representative works with design concepts, construction approaches, engineering strategies, special functions, and electrochemical results are listed and discussed in detail. Finally, the existing challenges and issues are concluded and analyzed, and future perspectives and research directions are given. This review can provide new guidance for the future design and practical applications of phosphorus- and phosphide-based materials used in AIBs.

Hierarchical Core-Shell Co2 N/CoP Embedded in N, P-doped Carbon Nanotubes as Efficient Oxygen Reduction Reaction Catalysts for Zn-air Batteries

Projecting a cost-effective and highly efficient electrocatalyst for the oxygen reaction reduction (ORR) counts a great deal for Zn-air batteries. Herein, a hierarchical core-shell ORR catalyst (Co₂ N/CoP@PNCNTs) is developed by embedding cobalt phosphides and/or cobalt nitrides as the core into N, P-doped carbon nanotubes (PNCNTs) as the shell via one-step carbonization, nitridation, and phosphorization of pyrolyzing Co-MOF precursor. The globally N, P-doped structure of Co₂ N/CoP@PNCNTs demonstrates an outstanding electrocatalytic activity in the alkaline solution with the onset and half-wave potentials of 1.07 and 0.85 V respectively. Moreover, a Zn-air battery assembled from Co₂ N/CoP@PNCNTs as the air cathode delivers an open circuit potential of 1.49 V, a maximum power density of 151.1 mW cm^-2 and a specific capacity of 823.8 mAh kg^-1 . It is reflected that Co₂ N/CoP@PNCNTs provides a long-term durability with a slight decline of 15 h in the chronoamperometry measurement and an excellent charge-discharge stability with negligible voltage decay for 150 h at 10 mA cm^-2 in Zn-air batteries. The results reveal that Co₂ N/CoP@PNCNTs has superiority over most Co-N_x -C or Co_x P@C catalysts reported so far. The excellent catalytic properties and stability of Co₂ N/CoP@PNCNTs derive from synergistic effects between Co₂ N/CoP and mesoporous N, P-doped carbon nanotubes.

FeCo alloy encased in nitrogen-doped carbon for efficient formaldehyde removal: Preparation, electronic structure, and d-band center tailoring

Formaldehyde is a typical indoor air pollutant that has posed severely adverse effects on human health. Herein, a novel FeCo alloy nanoparticle-embedded nitrogen-doped carbon (FeCo@NC) was synthesized with the aim of tailoring the transition-metal d-band structure toward an improved formaldehyde oxidation activity for the first time. A unique core@shell metal-organic frameworks (MOFs) architecture with a Fe-based Prussian blue analogue core and Co-containing zeolite imidazole framework shell was firstly fabricated. Then, Fe and Co ion alloying was readily achieved owing to the inherent MOF porosity and interionic nonequilibrium diffusion occurring during pyrolysis. High-angle annular dark-field scanning transmission electron microscopy and X-ray absorption fine structure spectra confirm that small FeCo alloys in situ form in FeCo@NC, which exhibits a higher formaldehyde removal efficiency (93%) than the monometallic Fe-based catalyst and a remarkable CO₂ selectivity (85%) at room temperature. Density functional theory calculations indicate the number of electrons transferred from the metal core to the outer carbon layer is altered by alloying Fe and Co. More importantly, a downshift in the d-band center relative to the Fermi level occurs from - 0.93 to - 1.04 eV after introducing Co, which could alleviate the adsorption of reaction intermediates and greatly improve the catalytic performance.

Graphene-supported polyoxometalate entrapped in MIL-88A network with highly efficient conversion of polysulfides in Li-S batteries

Polyoxometalates (POMs) have been demonstrated to have strong anchoring and efficient catalysis for lithium polysulfides (LiPSs). However, the severe aggregation buries the effective active sites of POMs, along with poor...

Reversing electron transfer in a covalent triazine framework for efficient photocatalytic hydrogen evolution

Covalent triazine-based frameworks (CTFs) have emerged as some of the most important materials for photocatalytic water splitting. However, development of CTF-based photocatalytic systems with non-platinum cocatalysts for highly efficient hydrogen evolution still remains a challenge. Herein, we demonstrated, for the first time, a one-step phosphidation strategy for simultaneously achieving phosphorus atom bonding with the benzene rings of CTFs and the anchoring of well-defined dicobalt phosphide (Co₂P) nanocrystals (∼7 nm). The hydrogen evolution activities of CTFs were significantly enhanced under simulated solar-light (7.6 mmol h⁻¹ g⁻¹), more than 20 times higher than that of the CTF/Co₂P composite. Both comparative experiments and in situ X-ray photoelectron spectroscopy reveal that the strong interfacial P–C bonding and the anchoring of the Co₂P cocatalyst reverse the charge transfer direction from triazine to benzene rings, promote charge separation, and accelerate hydrogen evolution. Thus, the rational anchoring of transition-metal phosphides on conjugated polymers should be a promising approach for developing highly efficient photocatalysts for hydrogen evolution.

Reversing the electron transfer in a covalent triazine-based framework by Co₂P anchoring achieved highly efficient photocatalytic hydrogen evolution from water splitting.

Realizing high-performance and low-cost lithium-ion capacitor by regulating kinetic matching between ternary nickel cobalt phosphate microspheres anode with ultralong-life and super-rate performance and watermelon peel biomass-derived carbon cathode

Lithium-ion capacitors (LICs) are emerging as one of the most advanced energy storage devices by combining the virtues of both supercapacitors (SCs) and lithium-ion batteries (LIBs). However, the kinetic and capacity mismatch between anode and cathode is the main obstacle to wide applications of LICs. Therefore, the effective strategy of constructing a high-performance LIC is to improve the rate and cycle performance of the anode and the specific capacity of the cathode. Herein, the nickel cobalt phosphate (NiCoP) microspheres anode is demonstrated with robust structural integrity, high electrical conductivity, and fast kinetic feature. Simultaneously, the watermelon-peel biomass-derived carbon (WPBC) cathode is demonstrated a sustainable synthesis strategy with high specific capacity. As expected, the NiCoP exhibits high specific capacities (567 mAh g^-1 at 0.1 A g^-1), superior rate performance (300 mAh g^-1 at 1A g^-1), and excellent cycle stability (58 mAh g^-1 at 5 A g^-1 after 15,000 cycles). The WPBC possesses a high specific surface area (SSA) of 3303.6 m² g^-1 and a high specific capacity of 226 mAh g^-1 at 0.1 A g^-1. Encouragingly, the NiCoP//WPBC-6 LIC device can deliver high energy density (ED) of 127.4 ± 3.3 and 67 ± 3.8Wh kg^-1 at power density (PD) of 190 and 18240 W kg^-1 (76.4% capacity retention after 7000 cycles), respectively.

Activity Promotion of Core and Shell in Multifunctional Core-Shell Co2 P@NC Electrocatalyst by Secondary Metal Doping for Water Electrolysis and Zn-Air Batteries

Developing cost-efficient multifunctional electrocatalysts is highly critical for the integrated electrochemical energy-conversion systems such as water electrolysis based on hydrogen/oxygen evolution reactions (HER/OER) and metal-air batteries based on OER/oxygen reduction reactions (ORR). The core-shell structured materials with transition metal phosphide as the core and nitrogen-doped carbon (NC) as the shell have been known as promising HER electrocatalysts. However, their oxygen-related electrocatalytic activities still remain unsatisfactory, which severely limits their further applications. Herein an effective strategy to improve the core and shell performances of core-shell Co₂ P@NC electrocatalysts through secondary metal (e.g., Fe, Ni, Mo, Al, Mn) doping (termed M-Co₂ P@M-N-C) is reported. The as-synthesized M-Co₂ P@M-N-C electrocatalysts show multifunctional HER/OER/ORR activities and good integrated capabilities for overall water splitting and Zn-air batteries. Among the M-Co₂ P@M-N-C catalysts, Fe-Co₂ P@Fe-N-C electrocatalyst exhibits the best catalytic activities, which is closely related to the configuration of highly active species (Fe-doping Co₂ P core and Fe-N-C shell) and their subtle synergy, and a stable carbon shell for outstanding durability. Combination of electrochemical-based in situ Fourier transform infrared spectroscopy with extensive experimental investigation provides deep insights into the origin of the activity and the underlying electrocatalytic mechanisms at the molecular level.

Flower-like Spherical α-Ni(OH)2 Derived NiP2 as Superior Anode Material of Sodium-Ion Batteries

Transition metal phosphides (TMPs) are promising anode candidates for sodium-ion batteries, due to their high theoretical specific capacity and working potential. However, the low conductivity and excessive volume variation of TMPs during insertion/extraction of sodium ions result in a poor rate performance and long-term cycling stability, largely limiting their practical application. In this paper, NiP₂ nanoparticles encapsulated in three-dimensional graphene (NiP₂ @rGO) were obtained from the flower-like spherical α-Ni(OH)₂ by phosphating and carbon encapsulation processes. When used as a sodium-ion batteries anode material, the NiP₂ @rGO composite shows an excellent cycling performance (117 mA h g^-1 at 10 A g^-1 after 8000 cycles). The outstanding electrochemical performance of NiP₂ @rGO is ascribed to the synergistic effect of the rGO and NiP₂ . The rGO wrapped on the NiP₂ nanoparticles build a conductive way, improving ionic and electronic conductivity. The effective combination of NiP₂ nanoparticles with graphene greatly reduces the aggregation and pulverization of NiP₂ nanoparticles during the discharge/charge process. This study may shed light on the construction of high-performance anode materials for sodium-ion batteries and to other electrode materials.

Rational Confinement of Yttrium Vanadate within Three-Dimensional Graphene Aerogel: Electrochemical Analysis of Monoamine Neurotransmitter (Dopamine)

Real-time monitoring of neurotransmitter levels is of tremendous technological demand, which requires more sensitive and selective sensors over a dynamic concentration range. As a use case, we report yttrium vanadate within three-dimensional graphene aerogel (YVO/GA) as a novel electrocatalyst for detecting dopamine (DA). This synergy effect endows YVO/GA nanocomposite with good electrochemical behaviors for DA detection compared to other electrodes. Benefiting from tailorable properties, it provides a large specific surface area, rapid electron transfer, more active sites, good catalytic activity, synergic effect, and high conductivity. The essential analytical parameters were estimated from the calibration plot, such as a limit of detection (1.5 nM) and sensitivity (7.1 μA μM^-1 cm^-2) with the YVO/GA sensor probe electrochemical approach. The calibration curve was fitted with the correlation coefficient of 0.994 in the DA concentration range from 0.009 to 83 μM, which is denoted as the linear working range. We further demonstrate the proposed YVO/GA sensor's applicability to detect DA in human serum sample with an acceptable recovery range. Our results imply that the developed sensor could be applied to the early analysis of dementia, psychiatric, and neurodegenerative disorders.

Crystal Phase-Controlled Synthesis of the CoP@Co2P Heterostructure with 3D Nanowire Networks for High-Performance Li-Ion Capacitor Applications

The paramount focus in the construction of lithium-ion capacitors (LICs) is the development of anode materials with high reversible capacity and fast kinetics to overcome the mismatch of kinetics and capacity between the anode and cathode. Herein, a strategy is presented for the controllable synthesis of cobalt-based phosphides with various morphologies by adjusting the time of the phosphidation process, including 3D hierarchical needle-stacked diabolo-shaped CoP nanorods, 3D hierarchical stick-stacked diabolo-shaped Co₂P nanorods, and 3D hierarchical heterostructure CoP@Co₂P nanorods. 3D hierarchical nanostructures and a highly conductive project to accommodate volume changes are rational designs to achieve a robust construction, effective electron-ion transportation, and rapid kinetics characteristics, thus leading to excellent cycling stability and rate performance. Owing to these merits, the 3D hierarchical CoP, Co₂P, and CoP@Co₂P nanorods demonstrate prominent specific capacities of 573, 609, and 621 mA h g^-1 at 0.1 A g^-1 over 300 cycles, respectively. In addition, a high-performance CoP@Co₂P//AC LIC is successfully constructed, which can achieve high energy densities of 166.2 and 36 W h kg^-1 at power densities of 175 and 17524 W kg^-1 (83.7% capacity retention after 12000 cycles). Therefore, the controllable synthesis of various simultaneously constructed crystalline phases and morphologies can be used to fabricate other advanced energy storage devices.

Co2P nanoparticle/multi-doped porous carbon nanosheets for the oxygen evolution reaction

Co₂P hybridized with multi-doped carbon nanoleaves is obtained via direct carbonization of ZIF-L/PEI/PA and show good electro-catalytic performance in OER.

Ion Reservoir Enabled by Hierarchical Bimetallic Sulfides Nanocages Toward Highly Effective Sodium Storage

Designing and constructing bimetallic hierarchical structures is vital for the conversion-alloy reaction anode of sodium-ion batteries (SIBs). Particularly, the rationally designed hetero-interface engineering can offer fast diffusion kinetics in the interface, leading to the improved high-power surface pseudocapacitance and cycling stability for SIBs. Herein, the hierarchical zinc-tin sulfide nanocages (ZnS-NC/SnS₂ ) are constructed through hydrothermal and sulfuration reactions. The unconventional hierarchical design with internal void space greatly optimizes the structure stability, and bimetallic sulfide brings a bimetallic composite interface and N heteroatom doping, which are devoted to high electrochemical activity and improved interfacial charge transfer rate for Na⁺ storage. Remarkably, the ZnS-NC/SnS₂ composite anode exhibits a delightful reversible capacity of 595 mAh g^-1 after 100 cycles at 0.2 A g^-1 , and long cycling capability for 500 cycles with a low capacity loss of 0.08% per cycle at 1 A g^-1 . This study opens up a new route for rationally constructing hierarchical heterogeneous interfaces and sheds new light on efficient anode material for SIBs.

The Progress of Cobalt-Based Anode Materials for Lithium Ion Batteries and Sodium Ion Batteries

Limited by the development of energy storage technology, the utilization ratio of renewable energy is still at a low level. Lithium/sodium ion batteries (LIBs/SIBs) with high-performance electrochemical performances, such as large-scale energy storage, low costs and high security, are expected to improve the above situation. Currently, developing anode materials with better electrochemical performances is the main obstacle to the development of LIBs/SIBs. Recently, a variety of studies have focused on cobalt-based anode materials applied for LIBs/SIBs, owing to their high theoretical specific capacity. This review systematically summarizes the recent status of cobalt-based anode materials in LIBs/SIBs, including Li+/Na+ storage mechanisms, preparation methods, applications and strategies to improve the electrochemical performance of cobalt-based anode materials. Furthermore, the current challenges and prospects are also discussed in this review. Benefitting from these results, cobalt-based materials can be the next-generation anode for LIBs/SIBs.

Zinc Phosphides as Outstanding Sodium-Ion Battery Anodes

To design a high-performance sodium-ion battery anode, binary zinc phosphides (ZnP₂ and Zn₃P₂) were synthesized by a facile solid-state heat treatment process, and their Na storage characteristics were evaluated. The Na reactivity of ZnP₂ was better than that of Zn₃P₂. Therefore, a C-modified ZnP₂-based composite (ZnP₂-C) was fabricated to achieve better electrochemical performance. To investigate the electrochemical reaction mechanism of ZnP₂-C during sodiation/desodiation, various ex situ analytical techniques were employed. During sodiation, ZnP₂ in the composite was transformed into NaZn₁₃ and Na₃P phases, exhibiting a one-step conversion reaction. Conversely, Zn and P in NaZn₁₃ and Na₃P, respectively, were fully recombined to the original ZnP₂ phase during desodiation. Owing to the one-step conversion/recombination of ZnP₂ in the composite during cycling, the ZnP₂-C showed high electrochemical performance with a highly reversible capacity of 883 mA h g^-1 after 130 cycles with no capacity deterioration and a fast C-rate capability of 500 mA h g^-1 at 1 C and 350 mA h g^-1 at 3 C.

Flower-like NiO/ZnO hybrid coated with N-doped carbon layer derived from metal-organic hybrid frameworks as novel anode material for high performance sodium-ion batteries

Metal-organic hybrid frameworks are considered as the promising precursor to prepare high performance anode materials for sodium-ion batteries (SIBs). In the present work, flower-like NiO/ZnO@NC with hollow and porous structure was prepared via a facile solvothermal and calcination process. The hollow and porous structure not only improve the electron transport capability, and but also inhibits the aggregation and accommodates the volume change of NiO/ZnO@NC. Meanwhile, the coated amorphous carbon layer could also increase the electron conductivity and buffer the huge volume expansion of active material NiO/ZnO. When used as anode for SIBs, NiO/ZnO@NC demonstrates a high specific capacity of 300 mAh g^-1 with good cycling stability for 150 cycles, fast charge and discharge capability (154 mAh g^-1 at 2500 mA g^-1) and superior long cycling life at high current density for 2500 cycles. The strategy in this work should provide a new insight into fabrication novel structural anode materials for high performance SIBs.

High Capacity and Energy Density of Zn-Ni-Co-P Nanowire Arrays as an Advanced Electrode for Aqueous Asymmetric Supercapacitor

Developing multicomponent transition-metal phosphides has become an efficient way to improve the capacitive performance of single-component transition-metal phosphides. However, reports on quaternary phosphides for supercapacitor applications are still scarce. Here, we report high capacity and energy density of Zn-Ni-Co-P quaternary phosphide nanowire arrays on nickel foam (ZNCP-NF) composed of highly conductive metal-rich phosphides as an advanced binder-free electrode in aqueous asymmetric supercapacitors. In a three-electrode system using the new electrode, a high specific capacity of 1111 C g^-1 was obtained at a current density of 10 A g^-1. Analysis of this aqueous asymmetric supercapacitor with ZNCP-NF as the positive electrode and commercial activated carbon as the negative electrode reveals a high energy density (37.59 Wh kg^-1 at a power density of 856.52 W kg^-1) and an outstanding cycling performance (capacity retention of 92.68% after 10 000 cycles at 2 A g^-1). Our results open a path for a new design of advanced electrode material for supercapacitors.

ZIF-Derived Cobalt-Containing N-Doped Carbon-Coated SiOx Nanoparticles for Superior Lithium Storage

N-Doped carbon-encapsulated SiO_x and Co nanoparticles are synthesized by the calcination of ZIF-67-coated SiO_x nanoparticles. This composite exhibits good electrochemical conductivity and superior accommodation to volume change from N-doped carbon and Co with SiO_x nanoparticles, exhibiting improved cycle and rate performances for lithium storage. It retains a capacity of 1044 mA h g^-1 over 150 cycles at 1.5 A g^-1, outperforming those without Co or N-doped carbon. It well confirms the contributions of Co- and N-doped carbon to the electrochemical properties of SiO_x. Even after 350 cycles at 1.0 A g^-1, this composite nonetheless delivers a capacity of 900 mA h g^-1. If it is coupled with LiFePO₄, the full cells show a stable cycling, indicating the promising application of this composite.

In situ fabrication of a rose-shaped Co2P2O7/C nanohybrid via a coordination polymer template for supercapacitor application

Using a coordination polymer as the template, the porous rose-shaped Co₂P₂O₇/C-X were fabricated by in situ hybrid Co₂P₂O₇ nanoparticles and nanocarbon for supercapacitor applications.

Recent progress on metal–organic framework-derived materials for sodium-ion battery anodes

Recent progress on MOF-derived materials, including carbon and metal oxides/sulfides/selenides/phosphides, as anode materials for sodium-ion batteries is summarized.

Embracing high performance potassium-ion batteries with phosphorus-based electrodes: a review

The ever-increasing global energy demand and rising price of raw materials adopted in currently prevalent lithium ion batteries (LIBs) have boosted the development of potassium ion batteries (KIBs). Despite the similarity in the working principle to LIBs, it remains a big challenge to select a suitable electrode material for KIBs. Phosphorus (P) and P-based composites have been identified as promising electrodes for LIBs or sodium ion batteries (NIBs) with remarkable electrochemical performance. Yet it was not until recent years that P-based materials have been explored as potential electrodes for KIBs. In this paper, we will try to provide a timely review of the current research progress of the P-based electrode materials, both cathodes and anodes, for KIBs. The synthetic strategies, electrochemical behaviours, and ion storage mechanisms will be discussed in detail. The challenges and future perspectives worth investigating will also been presented. Through timely update of the research progress and presentation of the existing arguments, it is expected that this review will help to clarify the puzzles encountered in current KIBs and benefit their future development and commercialization.

Interfacial Molecule Mediators in Cathodes for Advanced Li-S Batteries

The complicated reactions at the cathode-electrolyte interface in Li-S batteries are a large barrier for their successful commercialization. Herein, we developed a molecular design strategy and employed three small molecules acting as interfacial mediators to the cathodes of Li-S batteries. The theoretical calculation results show that the incorporation of tris(4-fluorophenyl)phosphine (TFPP) has a strong binding performance. The experimental results demonstrate that the strong chemical interactions between polysulfides and the F, P atoms in TFPP not only modify the kinetics of the electrochemical processes in the electrolyte but also promote the formation of short-chain clusters (Li₂S_x, x = 1, 2, 3, and 4) at the interface during the charge-discharge process. As a result, an optimized electrode exhibits a low capacity decay rate of 0.042% per cycle when the current rate is increased to 5 C over 1000 cycles.

Self-Supporting Hybrid Fiber Mats of Cu3P-Co2P/N-C Endowed with Enhanced Lithium/Sodium Ions Storage Performances

Recently, Cu₃P has been targeted as an alternative anode material for alkali-metal-ion batteries because of their safety potential and high volumetric capacity. However, designing a high-rate Cu₃P electrode with long durability is still faced with huge challenges. Here, we report a self-supporting three-dimensional (3D) composite of Cu₃P and Co₂P interconnected by N-doped C fibers (Cu₃P-Co₂P/N-C). The advanced 3D structure not only provides fast reaction kinetics but also improves the structural stability, leading to excellent rate capability and long-term cycling stability, and pseudocapacitance behavior is also beneficial to the high rate performance. Additionally, the synergistic effects between Cu₃P, Co₂P, and N-doped carbon can increase the electrical conductivity and active sites, ensuring more ion storage. The Cu₃P-Co₂P/N-C anode for lithium-ion batteries delivers high discharge capacity, superior rate performance, and ultralong lifespan over 2000 cycles accompanied by a stable capacity of around 316.9 mAh/g at 5 A/g. When the 3D structured material works in sodium-ion batteries, it also displays improved electrochemical performance. Our method provides a new insight to design advanced metal phosphides anodes for energy storage devices.

MOF derived CoP-decorated nitrogen-doped carbon polyhedrons/reduced graphene oxide composites for high performance supercapacitors

A CoP-NPC/RGO composite prepared through an efficient pyrolysis–phosphidation–assembly strategy exhibits an enhanced electrochemical performance.

Electrospun Kraft Lignin/Cellulose Acetate-Derived Nanocarbon Network as an Anode for High-Performance Sodium-Ion Batteries

An innovative nanocarbon network material was synthesized from electrospun kraft lignin and cellulose acetate blend nanofibers after carbonization at 1000 °C in a nitrogen atmosphere, and its electrochemical performance was evaluated as an anode material in sodium-ion batteries. Apart from its unique network architecture, introduced carbon material possesses high oxygen content of 13.26%, wide interplanar spacing of 0.384 nm, and large specific surface area of 540.95 m²·g^-1. The electrochemical test results demonstrate that this new nanocarbon network structure delivers a reversible capacity of 340 mA h·g^-1 at a current density of 50 mA·g^-1 after 200 cycles and exhibits a high rate capacity by delivering a capacity of 103 mA h·g^-1 at an increased current density of 400 mA·g^-1. The present work rendered an innovative approach for preparing nanocarbon materials for energy-storage applications and could open up new avenues for novel nanocarbon fabrication from green and environmentally friendly raw materials.

Layered g-C3N4@Reduced Graphene Oxide Composites as Anodes with Improved Rate Performance for Lithium-Ion Batteries

As important anodes in lithium-ion batteries, graphene is always faced with the aggregation problem that makes most of the active sites lose their function at high current densities, resulting in low Li-ion intercalation capacity and poor rate performance. To address this issue, a layered g-C₃N₄@reduced graphene oxide composite (g-C₃N₄@RGO) was prepared via a scalable and easy strategy. The resultant g-C₃N₄@RGO composite possesses large interlayer distances, rich N-active sites, and a microporous structure, which largely improves Li storage performance. It shows excellent cycle stability (899.3 mA h g^-1 after 350 cycles under 500 mA g^-1) and remarkable rate performance (595.1 mA h g^-1 after 1000 cycles under 1000 mA g^-1). Moreover, the g-C₃N₄@RGO electrode exhibits desired capacity retention and relatively high initial Coulombic efficiency of 58.8%. Impressively, this result is better than that of RGO (29.1%) and most of RGO-based anode materials reported in the literature. Especially, the g-C₃N₄@RGO-based electrode is enough to power two tandem red-light-emitting diodes and run a digital watch. Interestingly, the electronic watch can work continuously for more than 20 days. This novel strategy shows the great potential of g-C₃N₄@RGO composites as energy-storage materials.

A versatile strategy for ultrathin SnS2 nanosheets confined in a N-doped graphene sheet composite for high performance lithium and sodium-ion batteries

Ultrathin SnS₂ nanosheets confined in N-doped graphene sheets composite is synthesized by using a simple thermal decomposition method and as excellent electrodes for lithium/sodium-ion batteries.