Reconstruction of Conformal Nanoscale MnO on Graphene as a High‐Capacity and Long‐Life Anode Material for Lithium Ion Batteries

To tackle the issue of inferior cycle stability and rate capability for MnO anode materials in lithium ion batteries, a facile strategy is explored to prepare a hybrid material consisting of MnO nanocrystals grown on conductive graphene nanosheets. The prepared MnO/graphene hybrid anode exhibits a reversible capacity as high as 2014.1 mAh g^?1 after 150 discharge/charge cycles at 200 mA g^?1, excellent rate capability (625.8 mAh g^?1 at 3000 mA g^?1), and superior cyclability (843.3 mAh g^?1 even after 400 discharge/charge cycles at 2000 mA g^?1 with only 0.01% capacity loss per cycle). The results suggest that the reconstruction of the MnO/graphene electrodes is intrinsic due to conversion reactions. A long‐term stable nanoarchitecture of graphene‐supported ultrafine manganese oxide nanoparticles is formed upon cycling, which yields a long‐life anode material for lithium ion batteries. The lithiation and delithiation behavior suggests that the further oxidation of Mn(II ) to Mn(IV ) and the interfacial lithium storage upon cycling contribute to the enhanced specific capacity. The excellent rate capability benefits from the presence of conductive graphene and a short transportation length for both lithium ions and electrons. Moreover, the as‐formed hybrid nanostructure of MnO on graphene may help achieve faster kinetics of conversion reactions.     

Layered P2‐Type K0.65Fe0.5Mn0.5O2 Microspheres as Superior Cathode for High‐Energy Potassium‐Ion Batteries

Potassium‐ion batteries have been regarded as the potential alternatives to lithium‐ion batteries (LIBs) due to the low cost, earth abundance, and low potential of K (?2.936 vs standard hydrogen electrode (SHE)). However, the lack of low‐cost cathodes with high energy density and long cycle life always limits its application. In this work, high‐energy layered P2‐type hierarchical K_0.65Fe_0.5Mn_0.5O₂ (P2‐KFMO) microspheres, assembled by the primary nanoparticles, are fabricated via a modified solvent‐thermal method. Benefiting from the unique microspheres with primary nanoparticles, the K⁺ intercalation/deintercalation kinetics of P2‐KFMO is greatly enhanced with a stabilized cathodic electrolyte interphase on the cathode. The P2‐KFMO microsphere presents a highly reversible potassium storage capacity of 151 mAh g^?1 at 20 mA g^?1, fast rate capability of 103 mAh g^?1 at 100 mA g^?1, and long cycling stability with 78% capacity retention after 350 cycles. A full cell with P2‐KFMO microspheres as cathode and hard carbon as anode is constructed, which exhibits long‐term cycling stability (>80% of retention after 100 cycles). The present high‐performance P2‐KFMO microsphere cathode synthesized using earth‐abundant elements provides a new cost‐effective alternative to LIBs for large‐scale energy storage.     

General Synthesis of Dual Carbon‐Confined Metal Sulfides Quantum Dots Toward High‐Performance Anodes for Sodium‐Ion Batteries

Sponge‐like composites assembled by cobalt sulfides quantum dots (Co₉S₈ QD), mesoporous hollow carbon polyhedral (HCP) matrix, and a reduced graphene oxide (rGO) wrapping sheets are synthesized by a simultaneous thermal reduction, carbonization, and sulfidation of zeolitic imidazolate frameworks@GO precursors. Specifically, Co₉S₈ QD with size less than 4 nm are homogenously embedded within HCP matrix, which is encapsulated in macroporous rGO, thereby leading to the double carbon‐confined hierarchical composites with strong coupling effect. Experimental data combined with density functional theory calculations reveal that the presence of coupled rGO not only prevents the aggregation and excessive growth of particles, but also expands the lattice parameters of Co₉S₈ crystals, enhancing the reactivity for sodium storage. Benefiting from the hierarchical porosity, conductive network, structural integrity, and a synergistic effect of the components, the sponge‐like composites used as binder‐free anodes manifest outstanding sodium‐storage performance in terms of excellent stable capacity (628 mAh g^?1 after 500 cycles at 300 mA g^?1) and exceptional rate capability (529, 448, and 330 mAh g^?1 at 1600, 3200, and 6400 mA g^?1). More importantly, the synthetic method is very versatile and can be easily extended to fabricate other transition‐metal‐sulfides‐based sponge‐like composites with excellent electrochemical performances.     

3D MoS2–Graphene Microspheres Consisting of Multiple Nanospheres with Superior Sodium Ion Storage Properties

A novel anode material for sodium‐ion batteries consisting of 3D graphene microspheres divided into several tens of uniform nanospheres coated with few‐layered MoS₂ by a one‐pot spray pyrolysis process is prepared. The first discharge/charge capacities of the composite microspheres are 797 and 573 mA h g^?1 at a current density of 0.2 A g^?1. The 600th discharge capacity of the composite microspheres at a current density of 1.5 A g^?1 is 322 mA h g^?1. The Coulombic efficiency during the 600 cycles is as high as 99.98%. The outstanding Na ion storage properties of the 3D MoS₂–graphene composite microspheres may be attributed to the reduced stacking of the MoS₂ layers and to the 3D structure of the porous graphene microspheres. The reduced stacking of the MoS₂ layers relaxes the strain and lowers the barrier for Na⁺ insertion. The empty nanospheres of the graphene offer voids for volume expansion and pathways for fast electron transfer during repeated cycling.     

Self‐Standing Porous LiCoO2 Nanosheet Arrays as 3D Cathodes for Flexible Li‐Ion Batteries

Self‐standing electrodes are the key to realize flexible Li‐ion batteries. However, fabrication of self‐standing cathodes is still a major challenge. In this work, porous LiCoO₂ nanosheet arrays are grown on Au‐coated stainless steel (Au/SS) substrates via a facile “hydrothermal lithiation” method using Co₃O₄ nanosheet arrays as the template followed by quick annealing in air. The binder‐free and self‐standing LiCoO₂ nanosheet arrays represent the 3D cathode and exhibit superior rate capability and cycling stability. In specific, the LiCoO₂ nanosheet array electrode can deliver a high reversible capacity of 104.6 mA h g^?1 at 10 C rate and achieve a capacity retention of 81.8% at 0.1 C rate after 1000 cycles. By coupling with Li₄Ti₅O₁₂ nanosheet arrays as anode, an all‐nanosheet array based LiCoO₂//Li₄Ti₅O₁₂ flexible Li‐ion battery is constructed. Benefiting from the 3D nanoarchitectures for both cathode and anode, the flexible LiCoO₂//Li₄Ti₅O₁₂ battery can deliver large specific reversible capacities of 130.7 mA h g^?1 at 0.1 C rate and 85.3 mA h g^?1 at 10 C rate (based on the weight of cathode material). The full cell device also exhibits good cycling stability with 80.5% capacity retention after 1000 cycles at 0.1 C rate, making it promising for the application in flexible Li‐ion batteries.     

Engineering Hierarchical Hollow Nickel Sulfide Spheres for High‐Performance Sodium Storage

Sodium‐ion batteries (SIBs) are considered as promising alternatives to lithium‐ion batteries (LIBs) for energy storage due to the abundance of sodium, especially for grid distribution systems. The practical implementation of SIBs, however, is severely hindered by their low energy density and poor cycling stability due to the poor electrochemical performance of the existing electrodes. Here, to achieve high‐capacity and durable sodium storage with good rate capability, hierarchical hollow NiS spheres with porous shells composed of nanoparticles are designed and synthesized by tuning the reaction parameters. The formation mechanism of this unique structure is systematically investigated, which is clearly revealed to be Ostwald ripening mechanism on the basis of the time‐dependent morphology evolution. The hierarchical hollow structure provides sufficient electrode/electrolyte contact, shortened Na⁺ diffusion pathways, and high strain‐tolerance capability. The hollow NiS spheres deliver high reversible capacity (683.8 mAh g^?1 at 0.1 A g^?1), excellent rate capability (337.4 mAh g^?1 at 5 A g^?1), and good cycling stability (499.9 mAh g^?1 with 73% retention after 50 cycles at 0.1 A g^?1).     

Flexible Solid‐State Supercapacitors with Enhanced Performance from Hierarchically Graphene Nanocomposite Electrodes and Ionic Liquid Incorporated Gel Polymer Electrolyte

High energy density, durability, and flexibility of supercapacitors are required urgently for the next generation of wearable and portable electronic devices. Herein, a novel strategy is introduced to boost the energy density of flexible soild‐state supercapacitors via rational design of hierarchically graphene nanocomposite (GNC) electrode material and employing an ionic liquid gel polymer electrolyte. The hierarchical graphene nanocomposite consisting of graphene and polyaniline‐derived carbon is synthesized as an electrode material via a scalable process. The meso/microporous graphene nanocomposites exhibit a high specific capacitance of 176 F g^?1 at 0.5 A g^?1 in the ionic liquid 1‐ethyl‐3‐methylimidazolium tetrafluoroborate (EMIBF₄) with a wide voltage window of 3.5 V, good rate capability of 80.7% in the range of 0.5–10 A g^?1 and excellent stability over 10 000 cycles, which is attributed to the superior conductivity (7246 S m^?1), and quite large specific surface area (2416 m² g^?1) as well as hierarchical meso/micropores distribution of the electrode materials. Furthermore, flexible solid‐state supercapacitor devices based on the GNC electrodes and gel polymer electrolyte film are assembled, which offer high specific capacitance of 180 F g^?1 at 1 A g^?1, large energy density of 75 Wh Kg^?1, and remarkable flexible performance under consecutive bending conditions.     

Iron Oxide Nanoparticle‐Encapsulated CNT Branches Grown on 3D Ozonated CNT Internetworks for Lithium‐Ion Battery Anodes

Multidimensional hierarchical architecturing is a promising chemical approach to provide unique characteristics synergistically integrated from individual nanostructured materials for energy storage applications. Herein, hierarchical complex hybrid architectures of CNT‐on‐OCNT‐Fe are reported, where iron oxide nanoparticles are encapsulated inside carbon nanotube (CNT) branches grown onto the ozone‐treated surface of 3D CNT internetworked porous structures. The activated surface of the 3D ozonated CNT (OCNT) interacts with the iron oxide nanoparticles, resulting in different chemical environments of inner and outer tubes and large surface area. The mixed phases of iron oxide nanoparticles are confined by full encapsulation inside the conductive nanotubes and act as catalysts to vertically grow the CNT branches. This unique hierarchical architecture allows CNT‐on‐OCNT‐Fe to achieve a reasonable capacity of >798 mA h g^?1 at 50 mA g^?1, with outstanding rate capability (≈72% capacity retention at rates from 50 to 1000 mA g^?1) and cyclic stability (>98.3% capacity retention up to 200 cycles at 100 mA g^?1 with a coulombic efficiency of >97%). The improved rate and cyclic capabilities are attributed to the hierarchical porosity of 3D OCNT internetworks, the shielding of CNT walls for encapsulated iron oxide nanoparticles, and a proximate electronic pathway for the isolated nanoparticles.     

Ultrafine Nickel‐Nanoparticle‐Enabled SiO2 Hierarchical Hollow Spheres for High‐Performance Lithium Storage

The high theoretical capacity and natural abundance of SiO₂ make it a promising high‐capacity anode material for lithium‐ion batteries. However, its widespread application is significantly hampered by the intrinsic poor electronic conductivity and drastic volume variation. Herein, a unique hollow structured Ni/SiO₂ nanocomposite constructed by ultrafine Ni nanoparticle (≈3 nm) functionalized SiO₂ nanosheets is designed. The Ni nanoparticles boost not only the electronic conductivity but also the electrochemical activity of SiO₂ effectively. Meanwhile, the hollow cavity provides sufficient free space to accommodate the volume change of SiO₂ during repeated lithiation/delithiation; the nanosheet building blocks reduce the diffusion lengths of lithium ions. Due to the synergistic effect between Ni and SiO₂, the Ni/SiO₂ composite delivers a high reversible capacity of 676 mA h g^?1 at 0.1 A g^?1. At a high current density of 10 A g^?1, a capacity of 337 mA h g^?1 can be retained after 1000 cycles.     

Yolk–Shell Structured Assembly of Bamboo‐Like Nitrogen‐Doped Carbon Nanotubes Embedded with Co Nanocrystals and Their Application as Cathode Material for Li–S Batteries

Despite their high theoretical specific capacity (1675 mA h g^?1), the practical application of Li–S batteries remains limited because the capacity rapidly degrades through severe dissolution of lithium polysulfide and the rate capability is low because of the low electronic conductivity of sulfur. This paper describes novel hierarchical yolk–shell microspheres comprising 1D bamboo‐like N‐doped carbon nanotubes (CNTs) encapsulating Co nanoparticles (Co@BNCNTs YS microspheres) as efficient cathode hosts for Li–S batteries. The microspheres are produced via a two‐step process that involves generation of the microsphere followed by N‐doped CNTs growth. The hierarchical yolk–shell structure enables efficient sulfur loading and mitigates the dissolution of lithium polysulfides, and metallic Co and N doping improves the chemical affinity of the microspheres with sulfur species. Accordingly, a Co@BNCNTs YS microsphere‐based cathode containing 64 wt% sulfur exhibits a high discharge capacity of 700.2 mA h g^?1 after 400 cycles at a current density of 1 C (based on the mass of sulfur); this corresponds to a good capacity retention of 76% and capacity fading rate of 0.06% per cycle with an excellent rate performance (752 mA h g^?1 at 2.0 C) when applied as cathode hosts for Li–S batteries.     

Single‐Phase Mixed Transition Metal Carbonate Encapsulated by Graphene: Facile Synthesis and Improved Lithium Storage Properties

Transition metal carbonates (TMCs) with complex composition and robust hybrid structure hold great potential as high‐performance electrode materials for lithium‐ion batteries (LIBs). However, poor ionic/electronic conductivities and large volume changes of TMCs during lithiation/delithiation processes have hindered their applications. Herein, single‐phase Mn? Co mixed carbonate composites encapsulated by reduced graphene oxide (Mn_xCo_1?xCO₃/RGO), in which Mn and Co species are distributed randomly in one crystal structure, are successfully synthesized through a facial liquid‐state method. When evaluated as LIB anodes, the Mn_xCo_1?xCO₃/RGO composites exhibit enhanced electrochemical performance compared with the reference CoCO₃/RGO and MnCO₃/RGO. Specifically, the Mn_0.7Co_0.3CO₃/RGO delivers an ultrahigh capacity of 1454 mA h g^?1 after 130 cycles at 100 mA g^?1 and exhibits an ultralong cycling stability (901 mA h g^?1 after 1500 cycles at 2000 mA g^?1). This is the best lithium storage performance among carbonate‐based anodes reported up to date. Such superb performance is attributed to the hybrid structure and enhanced electroconductivity due to the integration of Co and Mn into one crystal structure, which is complemented by electrochemical impedance spectroscopy and density functional theory calculations. The facile synthesis, promising electrochemical results, and scientific understanding of the Mn_xCo_1?xCO₃/RGO provides a design principle and encourages more research on TMCs‐based electrodes.     

Walnut‐Like Multicore–Shell MnO Encapsulated Nitrogen‐Rich Carbon Nanocapsules as Anode Material for Long‐Cycling and Soft‐Packed Lithium‐Ion Batteries

Metal oxide‐based nanomaterials are widely studied because of their high‐energy densities as anode materials in lithium‐ion batteries. However, the fast capacity degradation resulting from the large volume expansion upon lithiation hinders their practical application. In this work, the preparation of walnut‐like multicore–shell MnO encapsulated nitrogen‐rich carbon nanocapsules (MnO@NC) is reported via a facile and eco‐friendly process for long‐cycling Li‐ion batteries. In this hybrid structure, MnO nanoparticles are uniformly dispersed inside carbon nanoshells, which can simultaneously act as a conductive framework and also a protective buffer layer to restrain the volume variation. The MnO@NC nanocapsules show remarkable electrochemical performances for lithium‐ion batteries, exhibiting high reversible capability (762 mAh g^?1 at 100 mA g^?1) and stable cycling life (624 mAh g^?1 after 1000 cycles at 1000 mA g^?1). In addition, the soft‐packed full batteries based on MnO@NC nanocapsules anodes and commercial LiFePO₄ cathodes present good flexibility and cycling stability.     

Hollow Mesoporous Carbon Nanocubes: Rigid‐Interface‐Induced Outward Contraction of Metal‐Organic Frameworks

Novel carbon materials derived from metal‐organic frameworks (MOFs) have attracted much attention, but the commonly inevitable inward contraction during the carbonization process has restricted their structural variety and applications. In this work, a novel rigid‐interface induced outward contraction approach is reported for synthesizing hollow mesoporous carbon nanocubes (HMCNCs) by using ZIF‐8 nanocubes as precursors. HMCNCs exhibit a cubic morphology with the particle sizes slightly larger than ZIF‐8 nanocubes. Due to the unique outward contraction process, uniform carbon nanocubes with a hollow cavity, an outer microporous shell, and an inner mesoporous wall are simultaneously formed with a large pore size (25 nm), high surface area (1085.7 m² g^?1), high porosity (3.77 cm³ g^?1), and high nitrogen content (12.2%). When used as a cathode material for Li–SeS₂ batteries, the HMCNCs deliver a stable capacity of 812.6 mA h g^?1 at 0.2 A g^?1 after 100 cycles and an outstanding rate capability (455.1 mA h g^?1 at 5.0 A g^?1). The findings may pave the way for the construction of distinctive MOF‐derived carbon materials for various applications.     

Face‐to‐Face Contact and Open‐Void Coinvolved Si/C Nanohybrids Lithium‐Ion Battery Anodes with Extremely Long Cycle Life

To develop high‐performance anode materials of lithium‐ion batteries (LIBs) instead of commercial graphite for practical applications, herein, a layer of silicon has been well‐anchored onto a 3D graphene/carbon nanotube (CNT) aerogels (CAs) framework with face‐to‐face contact and balanced open void by a simple chemical vapor deposition strategy. The engineered contact interface between CAs and Si creates high‐efficiency channels for the rapid electrons and lithium ions transport, and meanwhile, the balanced open‐void allows the free expansion of Si during cycling while maintaining high structural integrity due to the robust mechanical strength of 3D CAs framework. As a consequence, the as‐synthesized Si/CAs nanohybrids are highly stable anode materials for LIBs with a high reversible discharge capacity (1498 mAh g^?1 at 200 mA g^?1) and excellent rate capability (462 mAh g^?1 at 10 000 mA g^?1), which is much better than Si/graphene‐CNTs‐mixture (51 mAh g^?1 at 10 000 mA g^?1). More significantly, it is found that the Si/CAs nanohybrids display no obvious capacity decline even after 2000 cycles at a high current density of 10 000 mA g^?1. The present Si/CAs nanohybrids are one of the most stable Si‐based anode materials ever reported for LIBs to date.     

Multilayer‐Folded Graphene Ribbon Film with Ultrahigh Areal Capacitance and High Rate Performance for Compressible Supercapacitors

Limited by 2D geometric morphology and low bulk packing density, developing graphene‐based flexible/compressible supercapacitors with high specific capacitances (gravimetric/volumetric/areal), especially at high rates, is an outstanding challenge. Here, a strategy for the synthesis of free‐standing graphene ribbon films (GRFs) for high‐performance flexible and compressible supercapacitors through blade‐coating of interconnected graphene oxide ribbons and a subsequent thermal treatment process is reported. With an ultrahigh mass loading of 21 mg cm^?2, large ion‐accessible surface area, efficient electron and ion transport pathways as well as high packing density, the compressed multilayer‐folded GRF films (F‐GRF) exhibit ultrahigh areal capacitance of 6.7 F cm^?2 at 5 mA cm^?2, high gravimetric/volumetric capacitances (318 F g^?1, 293 F cm^?3), and high rate performance (3.9 F cm^?2 at 105 mA cm^?2), as well as excellent cycling stability (109% of capacitance retention after 40 000 cycles). Furthermore, the assembled F‐GRF symmetric supercapacitor with compressible and flexible characteristics, can deliver an ultrahigh areal energy density of 0.52 mWh cm^?2 in aqueous electrolyte, almost two times higher than the values obtained from symmetric supercapacitors with comparable dimensions.     

Bamboo‐Like Hollow Tubes with MoS2/N‐Doped‐C Interfaces Boost Potassium‐Ion Storage

Potassium‐ion batteries (KIBs) are new‐concept of low‐cost secondary batteries, but the sluggish kinetics and huge volume expansion during cycling, both rooted in the size of large K ions, lead to poor electrochemical behavior. Here, a bamboo‐like MoS₂/N‐doped‐C hollow tubes are presented with an expanded interlayer distance of 10 Å as a high‐capacity and stable anode material for KIBs. The bamboo‐like structure provides gaps along axial direction in addition to inner cylinder hollow space to mitigate the strains in both radial and vertical directions that ultimately leads to a high structural integrity for stable long‐term cycling. Apart from being a constituent of the interstratified structure the N‐doped‐C layers weave a cage to hold the potassiation products (polysulfide and the Mo nanoparticles) together, thereby effectively hindering the continuing growth of solid electrolyte interphase in the interior of particles. The density functional theory calculations prove that the MoS₂/N‐doped‐C atomic interface can provide an additional attraction toward potassium ion. As a result, it delivers a high capacity at a low current density (330 mAh g^?1 at 50 mA g^?1 after 50 cycles) and a high‐capacity retention at a high current density (151 mAh g^?1 at 500 mA g^?1 after 1000 cycles).     

Uniformly Confined Germanium Quantum Dots in 3D Ordered Porous Carbon Framework for High‐Performance Li‐ion Battery

Although abundant germanium (Ge)‐based anode materials have been explored to obtain high specific capacity, high rate performance, and long charge/discharge lifespans for lithium‐ion batteries (LIBs), their performances are still far from satisfactory due to the intrinsic defects of Ge and the relatively intricate anode structure. To work out these issues, a 3D ordered porous N‐doped carbon framework with Ge quantum dots uniformly embedded (3DOP Ge@N? C) as a binder‐free anode for LIBs via a facile polystyrene colloidal nanospheres template‐confined strategy is proposed. This unique structure not only facilitates Li‐ion diffusion and electron transport that can guarantee rapid de/alloying reaction, but also alleviates the huge volume changes during reactions and improves cycling stability. Notably, the resulting anode delivers a high specific reversible capacity (≈1160 mA h g^?1 at 1 A g^?1), superior rate properties (exceeding 500 mA h g^?1 at 40 A g^?1), and excellent cycling stability (over 90% capacity retention after 1200 cycles even at 5 A g^?1). Furthermore, both the 3DOP Ge@N? C anode with high areal mass loading (up to 8 mg cm^?2) and the full cell coupled with LiFePO₄ cathode display high capacity and cycling stability, further indicative of the favorable real‐life application prospects for high‐energy LIBs.     

Platinum‐Coated Hollow Graphene Nanocages as Cathode Used in Lithium‐Oxygen Batteries

One of the formidable challenges facing aprotic lithium‐oxygen (Li‐O₂) batteries is the high charge overpotential, which induces the formation of byproducts, loss in efficiency, and poor cycling performance. Herein, the synthesis of the ultrasmall Pt‐coated hollow graphene nanocages as cathode in Li‐O₂ batteries is reported. The charge voltage plateau can reduce to 3.2 V at the current density of 100 mA g^?1, even maintain below 3.5 V when the current density increased to 500 mA g^?1. The unique hollow graphene nanocages matrix can not only provide numerous nanoscale tri‐phase regions as active sites for efficient oxygen reduction, but also offer sufficient amount of mesoscale pores for rapid oxygen diffusion. Furthermore, with strong atomic‐level oxygen absorption into its subsurface, ultrasmall Pt catalytically serves as the nucleation site for Li₂O₂ growth. The Li₂O₂ is subsequently induced into a favorable form with small size and amorphous state, decomposed more easily during recharge. Meanwhile, the conductive hollow graphene substrate can enhance the catalytic activity of noble metal Pt catalysts due to the graphene‐metal interfacial interaction. Benefiting from the above synergistic effects between the hollow graphene nanocages and the nanosized Pt catalysts, the ultrasmall Pt‐decorated graphene nanocage cathode exhibits enhanced electrochemical performances.     

Facile Preparation of High‐Content N‐Doped CNT Microspheres for High‐Performance Lithium Storage

Herein, high‐content N‐doped carbon nanotube (CNT) microspheres (HNCMs) are successfully synthesized through simple spray drying and one‐step pyrolysis. HNCM possesses a hierarchically porous architecture and high‐content N‐doping. In particular, HNCM800 (HNCM pyrolyzed at 800 °C) shows high nitrogen content of 12.43 at%. The porous structure derived from well‐interconnected CNTs not only offers a highly conductive network and blocks diffusion of soluble lithium polysulfides (LiPSs) in physical adsorption, but also allows sufficient sulfur infiltration. The incorporation of N‐rich CNTs provides strong chemical immobilization for LiPSs. As a sulfur host for lithium–sulfur batteries, good rate capability and high cycling stability is achieved for HNCM/S cathodes. Particularly, the HNCM800/S cathode delivers a high capacity of 804 mA h g^?1 at 0.5 C after 1000 cycles corresponding to low fading rate (FR) of only 0.011% per cycle. Remarkably, the cathode with high sulfur loading of 6 mg cm^?2 still maintains high cyclic stability (capacity of 555 mA h g^?1 after 1000 cycles, FR 0.038%). Additionally, CNT/Co₃O₄ microspheres are obtained by the oxidation of CNTs/Co in the air. The as‐prepared CNT/Co₃O₄ microspheres are employed as an anode for lithium‐ion batteries and present excellent cycling performance.     

Local Built‐In Electric Field Enabled in Carbon‐Doped Co3O4 Nanocrystals for Superior Lithium‐Ion Storage

In this work, a novel concept of introducing a local built‐in electric field to facilitate lithium‐ion transport and storage within interstitial carbon (C‐) doped nanoarchitectured Co₃O₄ electrodes for greatly improved lithium‐ion storage properties is demonstrated. The imbalanced charge distribution emerging from the C‐dopant can induce a local electric field, to greatly facilitate charge transfer. Via the mechanism of “surface locking” effect and in situ topotactic conversion, unique sub‐10 nm nanocrystal‐assembled Co₃O₄ hollow nanotubes (HNTs) are formed, exhibiting excellent structural stability. The resulting C‐doped Co₃O₄ HNT‐based electrodes demonstrate an excellent reversible capacity ≈950 mA h g^?1 after 300 cycles at 0.5 A g^?1 and superior rate performance with ≈853 mA h g^?1 at 10 A g^?1.