Prolifera‐Green‐Tide as Sustainable Source for Carbonaceous Aerogels with Hierarchical Pore to Achieve Multiple Energy Storage

The increasing demand for efficient energy storage and conversion devices has aroused great interest in designing advanced materials with high specific surface areas, multiple holes, and good conductivity. Here, we report a new method for fabricating a hierarchical porous carbonaceous aerogel (HPCA) from renewable seaweed aerogel. The HPCA possesses high specific surface area of 2200 m² g^?1 and multilevel micro/meso/macropore structures. These important features make HPCA exhibit a reversible lithium storage capacity of 827.1 mAh g^?1 at the current density of 0.1 A g^?1, which is the highest capacity for all the previously reported nonheteroatom‐doped carbon nanomaterials. It also shows high specific capacitance and excellent rate performance for electric double layer capacitors (260.6 F g^?1 at 1 A g^?1 and 190.0 F g^?1 at 50 A g^?1), and long cycle life with 91.7% capacitance retention after 10 000 cycles at 10 A g^?1. The HPCA also can be used as support to assemble Co₃O₄ nanowires (Co₃O₄@HPCA) for constructing a high performance pseudocapacitor with the maximum specific capacitance of 1167.6 F g^?1 at the current density of 1 A g^?1. The present work highlights the first example in using prolifera‐green‐tide as a sustainable source for developing advanced carbon porous aerogels to achieve multiple energy storage.     

A Lyotropic Liquid‐Crystal‐Based Assembly Avenue toward Highly Oriented Vanadium Pentoxide/Graphene Films for Flexible Energy Storage

A novel lyotropic liquid‐crystal (LC) based assembly strategy is developed for the first time, to fabricate composite films of vanadium pentoxide (V₂O₅) nanobelts and graphene oxide (GO) sheets, with highly oriented layered structures. It is found that similar lamellar LC phases can be simply established by V₂O₅ nanobelts alone or by a mixture of V₂O₅ nanobelts and GO nanosheets in their aqueous dispersions. More importantly, the LC phases can be retained with any proportion of V₂O₅ nanobelts and GO, which allows facile optimization of the ratio of each component in the resulting films. Named VrGO, composite films manifest high electrical conductivity, good mechanical stability, and excellent flexibility, which allow them to be utilized as high performance electrodes in flexible energy storage devices. As demonstrated in this work, the VrGO films containing 67 wt% V₂O₅ exhibit excellent capacitance of 166 F g^?1 at 10 A g^?1; superior to those of the previously reported composites of V₂O₅ and nanocarbon. Moreover, the VrGO film in flexible lithium ion batteries delivers a high capacity of 215 mAh g^?1 at 0.1 A g^?1; comparable to the best V₂O₅ based cathode materials.     

A Low‐Cost,Self‐Standing NiCo2O4@CNT/CNT Multilayer Electrode for Flexible Asymmetric Solid‐State Supercapacitors

The demand for a new generation of flexible, portable, and high‐capacity power sources increases rapidly with the development of advanced wearable electronic devices. Here we report a simple process for large‐scale fabrication of self‐standing composite film electrodes composed of NiCo₂O₄@carbon nanotube (CNT) for supercapacitors. Among all composite electrodes prepared, the one fired in air displays the best electrochemical behavior, achieving a specific capacitance of 1,590 F g^?1 at 0.5 A g^?1 while maintaining excellent stability. The NiCo₂O₄@CNT/CNT film electrodes are fabricated via stacking NiCo₂O₄@CNT and CNT alternately through vacuum filtration. Lightweight, flexible, and self‐standing film electrodes (≈24.3 µm thick) exhibit high volumetric capacitance of 873 F cm^?3 (with an areal mass of 2.5 mg cm^?2) at 0.5 A g^?1. An all‐solid‐state asymmetric supercapacitor consists of a composite film electrode and a treated carbon cloth electrode has not only high energy density (≈27.6 Wh kg^?1) at 0.55 kW kg^?1 (including the weight of the two electrodes) but also excellent cycling stability (retaining ≈95% of the initial capacitance after 5000 cycles), demonstrating the potential for practical application in wearable devices.     

Multifunctional Carbon for Electrochemical Double‐Layer Capacitors

Multifunctional carbon materials are prepared for application as an active electrode material in an electrochemical capacitor displaying both charge storage and binder properties. The synthesis of the materials involves the functionalization of high surface area Black Pearls 2000 carbon black by a covalent attachment of polyacrylic acid. The polyacrylic acid polymer is formed by atom transfer radical polymerization using 1‐(bromoethyl)benzene groups initially bonded to the carbon by spontaneous grafting from the corresponding diazonium ions. The grafting of 1‐(bromoethyl)benzene and polyacrylic acid is confirmed by thermogravimetric analysis, Fourier transform infrared spectroscopy, energy‐dispersive X‐ray spectroscopy, and nitrogen gas adsorption isotherm. The composite electrode films prepared from the modified carbon are more hydrophilic and have better wettability in an aqueous electrolyte than the one prepared with the unmodified carbon. The modified electrodes also show a higher specific capacitance (≈140 F g^?1), a wider working potential window (1.5 V) and excellent specific capacitance retention upon cycling (99.9% after 5000 cycles) in an aqueous 0.65 m K₂SO₄ electrolyte. Moreover, a relatively high specific capacitance (≈90 F g^?1) is maintained at a scan rate of 1000 mV s^?1 with the polyacrylic‐acid‐modified carbon electrode.     

Boosting the Electrical Double‐Layer Capacitance of Graphene by Self‐Doped Defects through Ball‐Milling

Improving the capacitance of carbon materials for supercapacitors without sacrificing their rate performance, especially volumetric capacitance at high mass loadings, is a big challenge because of the limited assessable surface area and sluggish electrochemical kinetics of the pseudocapacitive reactions. Here, it is demonstrated that “self‐doping” defects in carbon materials can contribute to additional capacitance with an electrical double‐layer behavior, thus promoting a significant increase in the specific capacitance. As an exemplification, a novel defect‐enriched graphene block with a low specific surface area of 29.7 m² g^?1 and high packing density of 0.917 g cm^?3 performs high gravimetric, volumetric, and areal capacitances of 235 F g^?1, 215 F cm^?3, and 3.95 F cm^?2 (mass loading of 22 mg cm^?2) at 1 A g^?1, respectively, as well as outstanding rate performance. The resulting specific areal capacitance reaches an ultrahigh value of 7.91 F m^?2 including a “self‐doping” defect contribution of 4.81 F m^?2, which is dramatically higher than the theoretical capacitance of graphene (0.21 F m^?2) and most of the reported carbon‐based materials. Therefore, the defect engineering route broadens the avenue to further improve the capacitive performance of carbon materials, especially for compact energy storage under limited surface areas.     

Ultralight and Binder‐Free All‐Solid‐State Flexible Supercapacitors for Powering Wearable Strain Sensors

Flexible energy storage devices play a pivotal role in realizing the full potential of flexible electronics. This work presents high‐performance, all‐solid‐state, flexible supercapacitors by employing an innovative multilevel porous graphite foam (MPG). MPGs exhibit superior properties, such as large specific surface area, high electric conductivity, low mass density, high loading efficiency of pseudocapacitive materials, and controlled corrugations for accommodating mechanical strains. When loaded with pseudocapacitive manganese oxide (Mn₃O₄), the MPG/Mn₃O₄ (MPGM) composites achieve a specific capacitance of 538 F g^?1 (1 mV s^?1) and 260 F g^?1 (1 mV s^?1) based on the mass of pure Mn₃O₄ and entire electrode composite, respectively. Both are among the best of Mn₃O₄‐based supercapacitors. The MPGM is mechanically robust and can go through 1000 mechanical bending cycles with only 1.5% change in electric resistance. When integrated as all‐solid‐state symmetric supercapacitors, they offer a full cell specific capacitance as high as 53 F g^?1 based on the entire electrode and retain 80% of capacitance after 1000 continuous mechanical bending cycles. Furthermore, the all‐solid‐state flexible supercapacitors are incorporated with strain sensors into self‐powered flexible devices for detection of both coarse and fine motions on human skins, i.e., those from finger bending and heart beating.     

A Scalable Free‐Standing V2O5/CNT Film Electrode for Supercapacitors with a Wide Operation Voltage (1.6 V) in an Aqueous Electrolyte

While vanadium oxides have many attractive pseudocapacitive features for energy storage, their applications are severely limited by the poor electronic conductivity and low specific surface area. To overcome these limitations, a scalable, free‐standing film electrode composed of intertwined V₂O₅ nanowires and carbon nanotubes (CNTs) using a blade coating process has been prepared. The unique architecture of this hybrid electrode greatly facilitates electronic transport along CNTs while maintaining rapid ion diffusion within V₂O₅ nanowires and fast electron transfer across the V₂O₅/CNTs interfaces. When tested in a neutral aqueous electrolyte, this hybrid film electrode demonstrates a volumetric capacitance of ≈460 F cm^?3. Moreover, a symmetric capacitor based on two identical film electrodes displays a wide operation voltage window of 1.6 V, delivering a volumetric energy density as high as 41 Wh L^?1.     

Polypyrrole‐Derived Activated Carbons for High‐Performance Electrical Double‐Layer Capacitors with Ionic Liquid Electrolyte

As electrical energy storage and delivery devices, carbon‐based electrical double‐layer capacitors (EDLCs) have attracted much attention for advancing the energy‐efficient economy. Conventional methods for activated carbon (AC) synthesis offer limited control of their surface area and porosity, which results in a typical specific capacitance of 70–120 F g^?1 in commercial EDLCs based on organic electrolytes and ionic liquids (ILs). Additionally, typical ACs produced from natural precursors suffer from the significant variation of their properties, which is detrimental for EDLC use in automotive applications. A novel method for AC synthesis for EDLCs is proposed. This method is based on direct activation of synthetic polymers. The proposed procedure allowed us to produce ACs with ultrahigh specific surface area of up to 3432 m² g^?1 and volume of 0.5–4 nm pores up to 2.39 cm³ g^?1. The application of the produced carbons in EDLCs based on IL electrolyte showed specific capacitance approaching 300 F g^?1, which is unprecedented for carbon materials, and 5–8% performance improvement after 10 000 charge–discharge cycles at the very high current density of 10 A g^?1. The remarkable characteristics of the produced materials and the capability of the fabricated EDLCs to operate safely in a wide electrochemical window at elevated temperatures, suggest that the proposed synthesis route offers excellent potential for large‐scale material production for EDLC use in electric vehicles and industrial applications.     

Fe3O4 Nanoparticles Confined in Mesocellular Carbon Foam for High Performance Anode Materials for Lithium‐Ion Batteries

Fe₃O₄ nanocrystals confined in mesocellular carbon foam (MSU‐F‐C) are synthesized by a “ host–guest ” approach and tested as an anode material for lithium‐ion batteries (LIBs). Briefly, an iron oxide precursor, Fe(NO₃)₃·9H₂O, is impregnated in MSU‐F‐C having uniform cellular pores ～30 nm in dia­meter, followed by heat‐treatment at 400 °C for 4 h under Ar. Magnetite Fe₃O₄ nanocrystals with sizes between 13–27 nm are then successfully fabricated inside the pores of the MSU‐F‐C, as confirmed by transmission electron microscopy (TEM), dark‐field scanning transmission electron microscopy (STEM), energy dispersive X‐ray spectroscopy (EDS), X‐ray diffraction (XRD), and nitrogen sorption isotherms. The presence of the carbon most likely allows for reduction of some of the Fe³⁺ ions to Fe²⁺ ions via a carbothermoreduction process. A Fe₃O₄/MSU‐F‐C nanocomposite with 45 wt% Fe₃O₄ exhibited a first charge capacity of 1007 mA h g^?1 (Li⁺ extraction) at 0.1 A g^?1 (～0.1 C rate) with 111% capacity retention at the 150^th cycle, and retained 37% capacity at 7 A g^?1 (～7 C rate). Because the three dimensionally interconnected open pores are larger than the average nanosized Fe₃O₄ particles, the large volume expansion of Fe₃O₄ upon Li‐insertion is easily accommodated inside the pores, resulting in excellent electrochemical performance as a LIB anode. Furthermore, when an ultrathin Al₂O₃ layer (<4 Å) was deposited on the composite anode using atomic layer deposition (ALD), the durability, rate capability and undesirable side reactions are significantly improved.     

Rational Construction of a Functionalized V2O5 Nanosphere/MWCNT Layer‐by‐Layer Nanoarchitecture as Cathode for Enhanced Performance of Lithium‐Ion Batteries

Vanadium pentoxide (V₂O₅) has received considerable attention owing to its potential application in energy storage with high specific capacity (294 mAh g^?1). However, the development of V₂O₅ cathodes has been limited by the intrinsically low electrical conductivity and slow electrochemical kinetics resulting in a significant capacity decay. In this article, in order to overcome the issues, V₂O₅ nanospheres and multiwalled carbon nanotubes (MWCNTs) are used to fabricate layer‐by‐layer composited paper as the cathode, which is prepared via electrostatic interaction and vacuum filtration by alternating the positively charged V₂O₅ nanospheres and the negatively charged terminated MWCNT solutions. As a result, the V₂O₅ nanospheres are closely intercalated between the adjacent MWCNT layers leading to minimize the disadvantage voids and enhance the overall conductivity of the composited electrode, which exhibits an enhanced cycling durability as well as improved rate capability.     

Layered H2Ti6O13‐Nanowires: A New Promising Pseudocapacitive Material in Non‐Aqueous Electrolyte

Layered H₂Ti₆O₁₃‐nanowires are prepared using a facile hydrothermal method and their Li‐storage behavior is investigated in non‐aqueous electrolyte. The achieved results demonstrate the pseudocapacitive characteristic of Li‐storage in the layered H₂Ti₆O₁₃‐nanowires, which is because of the typical nanosize and expanded interlayer space. The as‐prepared H₂Ti₆O₁₃‐nanowires have a high capacitance of 828 F g^?1 within the potential window from 2.0 to 1.0 V (vs. Li/Li⁺). An asymmetric supercapacitor with high energy density is developed successfully using H₂Ti₆O₁₃‐nanowires as a negative electrode and ordered mesoporous carbon (CMK‐3) as a positive electrode in organic electrolyte. The asymmetric supercapacitor can be cycled reversibly in the voltage range of 1 to 3.5 V and exhibits maximum energy density of 90 Wh kg^?1, which is calculated based on the mass of electrode active materials. This achieved energy density is much higher than previous reports. Additionally, H₂Ti₆O₁₃//CMK‐3 asymmetric supercapacitor displays the highest average power density of 11 000 W kg^?1. These results indicate that the H₂Ti₆O₁₃//CMK‐3 asymmetric supercapacitor should be a promising device for fast energy storage.     

Ultrathin‐Nanosheet‐Induced Synthesis of 3D Transition Metal Oxides Networks for Lithium Ion Battery Anodes

A general ultrathin‐nanosheet‐induced strategy for producing a 3D mesoporous network of Co₃O₄ is reported. The fabrication process introduces a 3D N‐doped carbon network to adsorb metal cobalt ions via dipping process. Then, this carbon matrix serves as the sacrificed template, whose N‐doping effect and ultrathin nanosheet features play critical roles for controlling the formation of Co₃O₄ networks. The obtained material exhibits a 3D interconnected architecture with large specific surface area and abundant mesopores, which is constructed by nanoparticles. Merited by the optimized structure in three length scales of nanoparticles–mesopores–networks, this Co₃O₄ nanostructure possesses superior performance as a LIB anode: high capacity (1033 mAh g^?1 at 0.1 A g^?1) and long‐life stability (700 cycles at 5 A g^?1). Moreover, this strategy is verified to be effective for producing other transition metal oxides, including Fe₂O₃, ZnO, Mn₃O₄, NiCo₂O₄, and CoFe₂O₄.     

Oxygen‐Deficient Bismuth Oxide/Graphene of Ultrahigh Capacitance as Advanced Flexible Anode for Asymmetric Supercapacitors

Oxygen‐deficient bismuth oxide (r‐Bi₂O₃)/graphene (GN) is designed, fabricated, and demonstrated via a facile solvothermal and subsequent solution reduction method. The ultrafine network bacterial cellulose (BC) as substrate for r‐Bi₂O₃/GN exhibits high flexibility, remarkable tensile strength (55.1 MPa), and large mass loading of 9.8 mg cm^?2. The flexible r‐Bi₂O₃/GN/BC anode delivers appreciable areal capacitance (6675 mF cm^?2 at 1 mA cm^?2) coupled with good rate capability (3750 mF cm^?2 at 50 mA cm^?2). In addition, oxygen vacancies have great influence on the capacitive performance of Bi₂O₃, delivering significantly improved capacitive values than the untreated Bi₂O₃ flexible electrode, and ultrahigh gravimetric capacitance of 1137 F g^?1 (based on the mass of r‐Bi₂O₃) can be obtained, achieving 83% of the theoretical value (1370 F g^?1). Flexible asymmetric supercapacitor is fabricated with r‐Bi₂O₃/GN/BC and Co₃O₄/GN/BC paper as the negative and positive electrodes, respectively. The operation voltage is expanded to 1.6 V, revealing a maximum areal energy density of 0.449 mWh cm^?2 (7.74 mWh cm^?3) and an areal power density of 40 mW cm^?2 (690 mW cm^?3). Therefore, this flexible anode with excellent electrochemical performance and high mechanical properties shows great potential in the field of flexible energy storage devices.     

Detonation Nanodiamond and Onion‐Like‐Carbon‐Embedded Polyaniline for Supercapacitors

The detonation nanodiamond is a versatile low‐cost nanomaterial with tunable properties and surface chemistry. In this work, it is shown how the application of nanodiamond (ND) can greatly increase the performance of electrochemically active polymers, such as polyaniline (PANI). Symmetric supercapacitors containing PANI‐ND nanocomposite electrodes with 3–28 wt% ND show dramatically improved cycle stability and higher capacitance retention at fast sweep rate than pure PANI electrodes. Contrary to other PANI‐carbon nanocomposites, specific capacitance of the selected PANI electrodes with embedded ND increases after 10 000 galvanostatic cycles and reaches 640 F g^?1, when measured in a symmetric two‐electrode configuration with 1 M H₂SO₄ electrolyte. The demonstrated specific capacitance is 3–4 times higher than that of the activated carbons and more than 15 times higher than that of ND and onion‐like carbon (OLC).     

ZnCl2 “Water‐in‐Salt” Electrolyte Transforms the Performance of Vanadium Oxide as a Zn Battery Cathode

Zn batteries potentially offer the highest energy density among aqueous batteries that are inherently safe, inexpensive, and sustainable. However, most cathode materials in Zn batteries suffer from capacity fading, particularly at a low current rate. Herein, it is shown that the ZnCl₂ “water‐in‐salt” electrolyte (WiSE) addresses this capacity fading problem to a large extent by facilitating unprecedented performance of a Zn battery cathode of Ca_0.20V₂O₅?0.80H₂O. Upon increasing the concentration of aqueous ZnCl₂ electrolytes from 1 m to 30 m, the capacity of Ca_0.20V₂O₅?0.80H₂O rises from 296 mAh g^?1 to 496 mAh g^?1; its absolute working potential increases by 0.4 V, and most importantly, at a low current rate of 50 mA g^?1, that is, C/10; its capacity retention increases from 8.4% to 51.1% over 100 cycles. Ex situ characterization results point to the formation of a new ready‐to‐dissolve phase on the electrode in the dilute electrolyte. The results demonstrate that the Zn‐based WiSE may provide the underpinning platform for the applications of Zn batteries for stationary grid‐level storage.     

Fe2O3 Nanoneedles on Ultrafine Nickel Nanotube Arrays as Efficient Anode for High‐Performance Asymmetric Supercapacitors

High performance of electrochemical energy storage devices depends on the smart structure engineering of electrodes, including the tailored nanoarchitectures of current collectors and subtle hybridization of active materials. To improve the anode supercapacitive performance of Fe₂O₃ for high‐voltage asymmetric supercapacitors, here, a hybrid core‐branch nanoarchitecture is proposed by integrating Fe₂O₃ nanoneedles on ultrafine Ni nanotube arrays (NiNTAs@Fe₂O₃ nanoneedles). The fabrication process employs a bottom‐up strategy via a modified template‐assisted method starting from ultrafine ZnO nanorod arrays, ensuring the formation of ultrafine Ni nanotube arrays with ultrathin tube walls. The novel developed NiNTAs@Fe₂O₃ nanoneedle electrode is demonstrated to be a highly capacitive anode (418.7 F g^?1 at 10 mV s^?1), matching well with the similarly built NiNTAs@MnO₂ nanosheet cathode. Contributed by the efficient electron collection paths and short ion diffusion paths in the uniquely designed anode and cathode, the asymmetric supercapacitors exhibit an excellent maximum energy density of 34.1 Wh kg^?1 at the power density of 3197.7 W kg^?1 in aqueous electrolyte and 32.2 Wh kg^?1 at the power density of 3199.5 W kg^?1 in quasi‐solid‐state gel electrolyte.     

Molecular Design of Mesoporous NiCo2O4 and NiCo2S4 with Sub‐Micrometer‐Polyhedron Architectures for Efficient Pseudocapacitive Energy Storage

Spinel‐type NiCo₂O₄ (NCO) and NiCo₂S₄ (NCS) polyhedron architectures with sizes of 500–600 nm and rich mesopores with diameters of 1–2 nm are prepared facilely by the molecular design of Ni and Co into polyhedron‐shaped zeolitic imidazolate frameworks as solid precursors. Both as‐prepared NCO and NCS nanostructures exhibit excellent pseudocapacitance and stability as electrodes in supercapacitors. In particular, the exchange of O^2? in the lattice of NCO with S^2? obviously improves the electrochemical performance. NCS shows a highly attractive capacitance of 1296 F g^?1 at a current density of 1 A g^?1, ultrahigh rate capability with 93.2% capacitance retention at 10 A g^?1, and excellent cycling stability with a capacitance retention of 94.5% after cycling at 1 A g^?1 for 6000 times. The asymmetric supercapacitor with an NCS negative electrode and an active carbon positive electrode delivers a very attractive energy density of 44.8 Wh kg^?1 at power density 794.5 W kg^?1, and a favorable energy density of 37.7 Wh kg^?1 is still achieved at a high power density of 7981.1 W kg^?1. The specific mesoporous polyhedron architecture contributes significantly to the outstanding electrochemical performances of both NCO and NCS for capacitive energy storage.     

Graphene Oxide Gel‐Derived,Free‐Standing,Hierarchically Porous Carbon for High‐Capacity and High‐Rate Rechargeable Li‐O2 Batteries

Lithium‐oxygen (Li‐O₂) batteries are one of the most promising candidates for high‐energy‐density storage systems. However, the low utilization of porous carbon and the inefficient transport of reactants in the cathode limit terribly the practical capacity and, in particular, the rate capability of state‐of‐the‐art Li‐O₂ batteries. Here, free‐standing, hierarchically porous carbon (FHPC) derived from graphene oxide (GO) gel in nickel foam without any additional binder is synthesized by a facile and effective in situ sol‐gel method, wherein the GO not only acts as a special carbon source, but also provides the framework of a 3D gel; more importantly, the proper acidity via its intrinsic COOH groups guarantees the formation of the whole structure. Interestingly, when employed as a cathode for Li‐O₂ batteries, the capacity reaches 11 060 mA h g^?1 at a current density of 0.2 mA cm^?2 (280 mA g^?1); and, unexpectedly, a high capacity of 2020 mA h g^?1 can be obtained even the current density increases ten times, up to 2 mA cm^?2 (2.8 A g^?1), which is the best rate performance for Li‐O₂ batteries reported to date. This excellent performance is attributed to the synergistic effect of the loose packing of the carbon, the hierarchical porous structure, and the high electronic conductivity of the Ni foam.     

Porosity‐ and Graphitization‐Controlled Fabrication of Nanoporous Silicon@Carbon for Lithium Storage and Its Conjugation with MXene for Lithium‐Metal Anode

Silicon (Si) and lithium metal are the most favorable anodes for high‐energy‐density lithium‐based batteries. However, large volume expansion and low electrical conductivity restrict commercialization of Si anodes, while dendrite formation prohibits the applications of lithium‐metal anodes. Here, uniform nanoporous Si@carbon (NPSi@C) from commercial alloy and CO₂ is fabricated and tested as a stable anode for lithium‐ion batteries (LIBs). The porosity of Si as well as graphitization degree and thickness of the carbon layer can be controlled by adjusting reaction conditions. The rationally designed porosity and carbon layer of NPSi@C can improve electronic conductivity and buffer volume change of Si without destroying the carbon layer or disrupting the solid electrolyte interface layer. The optimized NPSi@C anode shows a stable cyclability with 0.00685% capacity decay per cycle at 5 A g^?1 over 2000 cycles for LIBs. The energy storage mechanism is explored by quantitative kinetics analysis and proven to be a capacitance‐battery dual model. Moreover, a novel 2D/3D structure is designed by combining MXene and NPSi@C. As lithiophilic nucleation seeds, NPSi@C can induce uniform Li deposition with buffered volume expansion, which is proven by exploring Li‐metal deposition morphology on Cu foil and MXene@NPSi@C. The practical potential application of NPSi@C and MXene@NPSi@C is evaluated by full cell tests with a Li(Ni_0.8Co_0.1Mn_0.1)O₂ cathode.     

Rationally Designed Vanadium Pentoxide as High Capacity Insertion Material for Mg‐Ion

Owing to high energy density and economic viability, rechargeable Mg batteries are considered alternatives to lithium ion batteries. However besides the chevrel phase, none of the conventional inorganic cathode materials demonstrate reversible intercalation/deintercalation of Mg⁺² ions in an anhydrous electrolyte system. The lack of high voltage and high capacity cathode frustrates the realization of Mg batteries. Previous studies indicate that vanadium pentoxide (V₂O₅) has the potential to reversibly insert/extract Mg ions. However, many attempts to utilize V₂O₅ demonstrate limited electrochemical response, due to hindered Mg ion mobility in solid. Here, monodispersed spherical V₂O₅ with a hierarchical architecture is rationally designed, through a facile and scalable approach. The V₂O₅ spheres exhibit initial discharge capacity of 225 mA h g^?1 which stabilizes at ≈190 mA h g^?1 at 10 mA g^?1, much higher than previous reports. The V₂O₅ spheres exhibit specific discharge capacity of 55 mA h g^?1 at moderate current rate (50 mA g^?1) with negligible fading after 50 cycles (≈5%) and 100 cycle (≈13%), while it retains ≈95% columbic efficiency after 100 cycles demonstrating excellent stability during Mg⁺² ion intercalation/deintercalation. Most interestingly, exact phase and morphology are completely retained even after repeated Mg⁺² ion intercalation/deintercalation at different current rates, demonstrating pronounced electrochemical activity in an anhydrous magnesium electrolyte.