Efficiencies of Various in situ Polymerizations of Liquid Electrolytes and the Practical Implications for Quasi Solid-state Batteries.

In situ polymerization of liquid electrolytes is currently the most feasible way for constructing solid-state batteries, which, however, is affected by various interfering factors of reactions and so the electrochemical performance of cells. To disclose the effects from polymerization conditions, two types of generally used in situ polymerizing reactions of ring-opening polymerization (ROP) and double bond radical polymerization (DBRP) were investigated on the aspects of monomer conversion and electrochemical properties (Li+ -conductivity and interfacial stability). The ROP generated poly-ester and poly-carbonate show a high monomer conversion of ≈90 %, but suffer a poor Li+ -conductivity of lower than 2×10-5  S cm-1 at room temperature (RT). Additionally, the terminal alkoxy anion derived from the ROP is not resistant to high-voltage cathodes. While, the DBRP produced poly-VEC(vinyl ethylene carbonate) and poly-VC(vinylene carbonate) show lower monomer conversions of 50-80 %, delivering relatively higher Li+ -conductivities of 2×10-4  S cm-1 at RT. Compared two polymerizing reactions and four monomers, the VEC-based F-containing copolymer possesses advantages in Li+ -conductivity and antioxidant capacity, which also shows simultaneous stability towards Li-metal with the help of LiF-based passivating layer, allowing a long-term stable cycling of high-voltage quasi solid-state cells.

Influencing Factors on Li-ion Conductivity and Interfacial Stability of Solid Polymer Electrolytes, Exampled by Polycarbonates, Polyoxalates and Polymalonates.

The application of solid polymer electrolytes (SPEs) in all-solid-state(ASS) batteries is hindered by lower Li+ -conductivity and narrower electrochemical window. Here, three families of ester-based F-modified SPEs of poly-carbonate (PCE), poly-oxalate (POE) and poly-malonate (PME) were investigated. The Li+ -conductivity of these SPEs prepared from pentanediol are all higher than the counterparts made of butanediol, owing to the enhanced asymmetry and flexibility. Because of stronger chelating coordination with Li+ , the Li+ -conductivity of PME and POE is around 10 and 5 times of PCE. The trifluoroacetyl-units are observed more effective than -O-CH2 -CF2 -CF2 -CH2 -O- during the in situ passivation of Li-metal. Using trifluoroacetyl terminated POE and PCE as SPE, the interfaces with Li-metal and high-voltage-cathode are stabilized simultaneously, endowing stable cycling of ASS Li/LiNi0.6 Co0.2 Mn0.2 O2 (NCM622) cells. Owing to an enol isomerization of malonate, the cycling stability of Li/PME/NCM622 is deteriorated, which is recovered with the introduce of dimethyl-group in malonate and the suppression of enol isomerization. The coordinating capability with Li+ , molecular asymmetry and existing modes of elemental F, are all critical for the molecular design of SPEs.

Thermally Depolymerizable Polyether Electrolytes for Convenient and Low-Cost Recycling of LiTFSI.

Solid polymer electrolytes (SPEs) with LiTFSI (lithium bis(trifluoromethane sulfonimide)) are promising candidates for solid-state batteries, owing to their good interfacial contact with solid electrodes. Here, three copolymerized polyethers were prepared as SPEs, using the catalysts of SnF2 or SnF2 -LiPF6 . The thermal depolymerization of these polyethers was observed at elevated temperatures, which limits their operating temperature ranges. Once the catalyst is removed, the thermal degradation temperatures of these SPEs are raised by 30-55 °C, together with improved thermal performance in cells. For SPEs, the high price of LiTFSI is an obstacle for their large-scale application, and it's recycling is hindered by the strong interaction with polymers. By the thermal depolymerization of polyethers, LiTFSI can be easier reclaimed from above mentioned SPEs and even the commercial PEO(poly(ethylene-oxide)) based SPE in rates of 70-80 %, providing a low-cost strategy for the recycling of LiTFSI.

Polymers in Lithium-Sulfur Batteries.

Lithium-sulfur batteries (LSBs) hold great promise as one of the next-generation power supplies for portable electronics and electric vehicles due to their ultrahigh energy density, cost effectiveness, and environmental benignity. However, their practical application has been impeded owing to the electronic insulation of sulfur and its intermediates, serious shuttle effect, large volume variation, and uncontrollable formation of lithium dendrites. Over the past decades, many pioneering strategies have been developed to address these issues via improving electrodes, electrolytes, separators and binders. Remarkably, polymers can be readily applied to all these aspects due to their structural designability, functional versatility, superior chemical stability and processability. Moreover, their lightweight and rich resource characteristics enable the production of LSBs with high-volume energy density at low cost. Surprisingly, there have been few reviews on development of polymers in LSBs. Herein, breakthroughs and future perspectives of emerging polymers in LSBs are scrutinized. Significant attention is centered on recent implementation of polymers in each component of LSBs with an emphasis on intrinsic mechanisms underlying their specific functions. The review offers a comprehensive overview of state-of-the-art polymers for LSBs, provides in-depth insights into addressing key challenges, and affords important resources for researchers working on electrochemical energy systems.

Lithium-Conducting Branched Polymers: New Paradigm of Solid-State Electrolytes for Batteries.

The past decades have witnessed rapid development of lithium-based batteries. Significant research efforts have been progressively diverted from electrodes to electrolytes, particularly polymer electrolytes (PEs), to tackle the safety concern and promote the energy storage capability of batteries. To further increase the ionic conductivity of PEs, various branched polymers (BPs) have been rationally designed and synthesized. Compared with linear polymers, branched architectures effectively increase polymer segmental mobility, restrain crystallization, and reduce chain entanglement, thereby rendering BPs with greatly enhanced lithium transport. In this Mini Review, a diversity of BPs for PEs is summarized by scrutinizing their unique topologies and properties. Subsequently, the design principles for enhancing the physical properties, mechanical properties, and electrochemical performance of BP-based PEs (BP-PEs) are provided in which the ionic conduction is particularly examined in light of the Li+ transport mechanism. Finally, the challenges and future prospects of BP-PEs in this rapidly evolving field are outlined.

Robust wrinkled MoS2/N-C bifunctional electrocatalysts interfaced with single Fe atoms for wearable zinc-air batteries.

The ability to create highly efficient and stable bifunctional electrocatalysts, capable of oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) in the same electrolyte, represents an important endeavor toward high-performance zinc-air batteries (ZABs). Herein, we report a facile strategy for crafting wrinkled MoS2/N-doped carbon core/shell nanospheres interfaced with single Fe atoms (denoted MoS2@Fe-N-C) as superior ORR/OER bifunctional electrocatalysts for robust wearable ZABs with a high capacity and outstanding cycling stability. Specifically, the highly crumpled MoS2 nanosphere core is wrapped with a layer of single-Fe-atom-impregnated, N-doped carbon shell (i.e., Fe-N-C shell with well-dispersed FeN4 sites). Intriguingly, MoS2@Fe-N-C nanospheres manifest an ORR half-wave potential of 0.84 V and an OER overpotential of 360 mV at 10 mA⋅cm-2 More importantly, density functional theory calculations reveal the lowered energy barriers for both ORR and OER, accounting for marked enhanced catalytic performance of MoS2@Fe-N-C nanospheres. Remarkably, wearable ZABs assembled by capitalizing on MoS2@Fe-N-C nanospheres as an air electrode with an ultralow area loading (i.e., 0.25 mg⋅cm-2) display excellent stability against deformation, high special capacity (i.e., 442 mAh⋅g-1Zn), excellent power density (i.e., 78 mW⋅cm-2) and attractive cycling stability (e.g., 50 cycles at current density of 5 mA⋅cm-2). This study provides a platform to rationally design single-atom-interfaced core/shell bifunctional electrocatalysts for efficient metal-air batteries.

Recent Advances in Silicon-Based Electrodes: From Fundamental Research toward Practical Applications.

The increasing demand for higher-energy-density batteries driven by advancements in electric vehicles, hybrid electric vehicles, and portable electronic devices necessitates the development of alternative anode materials with a specific capacity beyond that of traditional graphite anodes. Here, the state-of-the-art developments made in the rational design of Si-based electrodes and their progression toward practical application are presented. First, a comprehensive overview of fundamental electrochemistry and selected critical challenges is given, including their large volume expansion, unstable solid electrolyte interface (SEI) growth, low initial Coulombic efficiency, low areal capacity, and safety issues. Second, the principles of potential solutions including nanoarchitectured construction, surface/interface engineering, novel binder and electrolyte design, and designing the whole electrode for stability are discussed in detail. Third, applications for Si-based anodes beyond LIBs are highlighted, specifically noting their promise in configurations of Li-S batteries and all-solid-state batteries. Fourth, the electrochemical reaction process, structural evolution, and degradation mechanisms are systematically investigated by advanced in situ and operando characterizations. Finally, the future trends and perspectives with an emphasis on commercialization of Si-based electrodes are provided. Si-based anode materials will be key in helping keep up with the demands for higher energy density in the coming decades.

Sustainable Internal Electric Field for Enhanced Photocatalysis: From Material Design to Energy Utilization.

The intrinsic internal electric field in a ferroelectric photocatalyst is beneficial for improving the photocatalytic properties because of its positive effect on the separation and migration of photogenerated carriers. However, this kind of internal electric field is static and easily saturated by inner and outer shielding effects, seriously restricting its potential in photocatalysis. To overcome this problem, a sustainable internal electric field was introduced into photocatalysis based on piezoelectric and pyroelectric effect, which exhibits good capability in consistently boosting photocatalytic activity, thus becoming a hot research topic. In this Perspective we summarize the recent significant progress in the construction of sustainable internal electric fields for facilitating photocatalysis from material design to energy utilization. Moreover, the fascinating influence of sustainable internal electric fields on carrier behavior is also discussed. Finally, a summary and outlook for building a sustainable internal electric field to further enhance photocatalytic performance are provided.

Layered Birnessite Cathode with a Displacement/Intercalation Mechanism for High-Performance Aqueous Zinc-Ion Batteries.

Mn-based rechargeable aqueous zinc-ion batteries (ZIBs) are highly promising because of their high operating voltages, attractive energy densities, and eco-friendliness. However, the electrochemical performances of Mn-based cathodes usually suffer from their serious structure transformation upon charge/discharge cycling. Herein, we report a layered sodium-ion/crystal water co-intercalated Birnessite cathode with the formula of Na0.55Mn2O4·0.57H2O (NMOH) for high-performance aqueous ZIBs. A displacement/intercalation electrochemical mechanism was confirmed in the Mn-based cathode for the first time. Na+ and crystal water enlarge the interlayer distance to enhance the insertion of Zn2+, and some sodium ions are replaced with Zn2+ in the first cycle to further stabilize the layered structure for subsequent reversible Zn2+/H+ insertion/extraction, resulting in exceptional specific capacities and satisfactory structural stabilities. Additionally, a pseudo-capacitance derived from the surface-adsorbed Na+ also contributes to the electrochemical performances. The NMOH cathode not only delivers high reversible capacities of 389.8 and 87.1 mA h g-1 at current densities of 200 and 1500 mA g-1, respectively, but also maintains a good long-cycling performance of 201.6 mA h g-1 at a high current density of 500 mA g-1 after 400 cycles, which makes the NMOH cathode competitive for practical applications.

BiOBr/Ag6Si2O7 heterojunctions for enhancing visible light catalytic degradation performances with a sequential selectivity enabled by dual synergistic effects.

Efficient separation of photogenerated electron-hole pairs is always one of the key factors boosting visible light photodegradation efficiency. Till now, there are few reports on the synergistic competitive consumption of photogenerated active species and the synergistic adsorption of organic contaminants to promote the performance of a designed heterojunction. Herein, we design and construct a novel BiOBr/Ag6Si2O7 heterojunction with the dual synergistic effects towards methylene blue (MB) and methyl orange (MO). The dual synergistic effects could avoid the combination of photogenerated h+/e- pairs, improve the adsorption efficiency, and even regulate the photodegradation efficiency. Thus, for an aqueous mixture of MB and MO, the BiOBr/Ag6Si2O7 photocatalyst exhibits largely improved adsorption capacities of the dyes by a multi-layer adsorption mode. Moreover, the photocatalyst could further promote the photodegradation rate of MO while slow that of MB due to the competitive consumption of photogenerated active species, showing a sequential selectivity phenomenon. Thanks to the dual synergistic effects, the adsorption capacity of MO increases 1379% higher than that of neat MO solution, and the photodegradation time decrease from 30 to 12 min with a rate constant of 0.22 min-1, 38% higher than that of neat MO solution.

Anisotropic CoFe2O4@Graphene Hybrid Aerogels with High Flux and Excellent Stability as Building Blocks for Rapid Catalytic Degradation of Organic Contaminants in a Flow-Type Setup.

Macroscopic three-dimensional catalytic materials could overcome the poor operability and avoid secondary pollution of common powdery counterparts, especially in flow-type setups. However, conventional isotropic graphene-based aerogels and foams have randomly distributed graphene sheets, which may cause stream erosion and reduce the flux seriously. Herein, for the first time, we design and fabricate a novel anisotropic CoFe2O4@graphene hybrid aerogel (CFO@GA-A) with a hydrothermal synthesis followed by directional-freezing and freeze-drying for a tube-like flow-type setup analogous to a wastewater discharge pipeline. The long and vertically aligned pores inside the aerogel provide an exceptional flux of 1100 L m-2 h-1, 450% higher than that of the rough and zigzag paths in the isotropic CoFe2O4@graphene hybrid aerogel (CFO@GA-I), and the leaching of metal ions is obviously inhibited by relieving the erosion of CoFe2O4. Besides, the CFO@GA-A could sustain the scour of high-speed flowing wastewater and maintain its structural stability. Therefore, organic contaminants of indigo carmine, methyl orange, orange II, malachite green, phenol, and norfloxacin could readily flow over the nanocatalysts and be degraded rapidly within 7.5-12.5 min at varied flow rates from 60 to 120 mL h-1. The CFO@GA-A also exhibits a much better long-term stability with removal efficiencies toward indigo carmine at 100%, 91%, and 85% for at least 30 h (60 mL h-1), 25 h (90 mL h-1), and 21 h (120 mL h-1), respectively. On the contrary, the CFO@GA-I exhibits unsatisfactory removal efficiencies of <40%. Interestingly, CFO@GA-A could also serve as building blocks to stack on each other for degrading intense flowing wastewater, exhibiting an outstanding composability. The high-flux and long-term stability make the CFO@GA-A promising as an ideal catalytic material for wastewater treatments.

Hierarchical mesoporous cobalt silicate architectures as high-performance sulfate-radical-based advanced oxidization catalysts.

Self-sacrificial biomass-derived silica is a rising and promising approach to fabricate large metal silicates, which are practical water treatment agents ascribed for easy sedimentation and separation. However, the original biomass architecture is difficult to be maintained and utilized. Furthermore, sufficient ion diffusion pathways need to be created to satisfy massive mass transport in large bulk materials. Herein, a series of metal silicates, including cobalt silicate (CoSiOx), copper silicate, nickel silicate, iron silicate, and magnesium silicate, are synthesized from Indocalamus tessellatus leaf as the biomass-derived silica source and investigated as catalysts in sulfate-radical-based advanced oxidization processes (SR-AOPs) for the first time. Among them, CoSiOx presents an analogical sandwich structure as a leaf-derived template of micron-level size. More importantly, the interior hollow nanotubes assembled by small nanosheets provide numerous pathways for ion diffusion and remarkably promote the mass transport in such large bulk materials. Owing to the combination of the unique structure with the high reactivity of Co (II) toward peroxymonosulfate, CoSiOx exhibits excellent catalytic performance with 0.242 and 0.153 min-1 rate constants for the removal of methylene blue and phenol, respectively, which outperforms/is comparable to that of the reported nanomaterials toward organic contaminants in SR-AOPs.

Dual-Carbon-Confined Fe7 S8 Anodes with Enhanced Electrochemical Catalytic Conversion Process for Ultralong Lithium Storage.

Although the electrochemical catalytic conversion process is effective in increasing the reversible capacity of lithium-ion batteries, the low contact efficiency between metal catalyst and substrate and pulverization of the solid electrolyte interface (SEI) film without protection are not beneficial for the electrochemical reactions. Herein, Fe7 S8 nanoparticles are confined by both reduced graphene oxide (RGO) and in-situ-formed amorphous carbon (C) to form dual-carbon-confined Fe7 S8 as a lithium-ion anode. The dual-carbon-confined structure provides a confined space to prevent pulverization of the SEI film and increases the local concentration of intermediate phases, which could be electrocatalytically decomposed by Fe nanoparticles formed in situ to increase the reversibility of the electrochemical reactions and gain high reversible capacity. In addition, the dual-carbon-confined structure ensures fast transfer of electrons and boosts transport of lithium ions due to the highly conductive dual-carbon shell. Thus, the Fe7 S8 /C/RGO anode delivers an excellent rate performance and long cycling stability. At current densities of 2000 and 5000 mA g-1 , the reversible capacities are 520 mA h g-1 over 1500 cycles and 294 mA h g-1 over 2000 cycles, respectively.

α-Fe2O3 Nanodisk/Bacterial Cellulose Hybrid Membranes as High-Performance Sulfate-Radical-Based Visible Light Photocatalysts under Stirring/Flowing States.

High activity and long-term stability are particularly important for peroxymonosulfate (PMS)-based degradation processes in wastewater treatment, especially under a flowing state. However, if the highly active nanomaterials are in a powder form, they could disperse well in water but would not be convenient for application under varied flow rates. A metal oxide/bacterial cellulose hybrid membrane fixed in a flowing bed is expected to solve these problems. Herein, α-Fe2O3 nanodisk/bacterial cellulose hybrid membranes as high-performance sulfate-radical-based visible light photocatalysts are synthesized for the first time. The bacterial cellulose with excellent mechanical stability and film-forming feature not only benefits the formation of a stable membrane to avoid the separation and recycling problems but also helps disperse and accommodate α-Fe2O3 nanodisks and thus enhances the visible light absorption performances, leading to an excellent PMS-based visible light degradation efficiency under both stirring and flowing states. Particularly, the optimized hybrid membrane photocatalyzes both cationic and anionic organic dyes under a flowing bed state for at least 84 h with the catalytic efficiency up to 100% and can be easily separated after the reaction, confirming its remarkable catalytic performance and long-term stability. Even under varied flow rates during the continuous process, it efficiently degrades rhodamine B and orange II from 3 to 16 mL h-1. When the flow rate goes back from high to low, the hybrid membrane quickly recovers its original performance, demonstrating the high activity and stability of the α-Fe2O3/bacterial cellulose membrane.

Enhanced lithium storage performances of novel layered nickel germanate anodes inspired by the spatial arrangement of lotus leaves.

The rapid capacity degradation of Ge-based materials hinders their practical application for next generation lithium ion batteries, which could be solved by synthesizing Ge-containing ternary oxides, with new structures and hybridizing with carbon nanomaterials. Herein, novel Ni3Ge2O5(OH)4 nanosheets were synthesized and distributed in situ on reduced graphene oxide (RGO) sheets, with both flat-lying and vertically-grown spatial distributions to imitate the growth of lotus leaves. These two types of Ni3Ge2O5(OH)4 nanosheets enhance their efficient contact with RGO, and increase the mass loading of active materials. Furthermore, the interfacial bonds between RGO sheets and Ni3Ge2O5(OH)4 nanosheets are introduced to improve the diffusion rate of lithium ions. The RGO sheets act as a buffer matrix to sustain the volume change and prevent the nanosheets from aggregation. Consequently, the chemically bonded Ni3Ge2O5(OH)4/RGO hybrid delivers a high specific capacity of 863 mA h g-1 over 75 cycles, which is much higher than those for neat Ni3Ge2O5(OH)4 nanosheets or the hybrid without the interfacial bonding. This study provides a novel perspective for designing high-performance Ge-based anode materials for advanced lithium ion batteries.

Neuron-Inspired Fe3O4/Conductive Carbon Filament Network for High-Speed and Stable Lithium Storage.

Construction of a continuous conductance network with high electron-transfer rate is extremely important for high-performance energy storage. Owing to the highly efficient mass transport and information transmission, neurons are exactly a perfect model for electron transport, inspiring us to design a neuron-like reaction network for high-performance lithium-ion batteries (LIBs) with Fe3O4 as an example. The reactive cores (Fe3O4) are protected by carbon shells and linked by carbon filaments, constituting an integrated conductance network. Thus, once the reaction starts, the electrons released from every Fe3O4 cores are capable of being transferred rapidly through the whole network directly to the external circuit, endowing the nanocomposite with tremendous rate performance and ultralong cycle life. After 1000 cycles at current densities as high as 1 and 2 A g-1, charge capacities of the as-synthesized nanocomposite maintain 971 and 715 mA h g-1, respectively, much higher than those of reported Fe3O4-based anode materials. The Fe3O4-based conductive network provides a new idea for future developments of high-rate-performance LIBs.

High Lithium Storage Capacity and Long Cycling Life Fe3S4 Anodes with Reversible Solid Electrolyte Interface Films and Sandwiched Reduced Graphene Oxide Shells.

Increasing demands for lithium-ion batteries (LIBs) with high energy density and high power density require highly reversible electrochemical reactions to enhance the cyclability and capacities of electrodes. As the reversible formation/decomposition of the solid electrolyte interface (SEI) film during the lithiation/delithiation process of Fe3S4 could bring about a higher capacity than its theoretical value, in the present work, synthesized Fe3S4 nanoparticles are sandwich-wrapped with reduced graphene oxide (RGO) to fabricate highly reversible and long cycling life anode materials for high-performance LIBs. The micron-sized long slit between sandwiched RGO sheets effectively prevents the aggregation of intermediate phases during the discharge/charge process and thus increases cycling capacity because of the reversible formation/decomposition of the SEI film driven by Fe nanoparticles. Furthermore, the RGO sheets interconnect with each other by a face-to-face mode to construct a more efficiently conductive network, and the maximum interfacial oxygen bridge bonds benefit the fast electron hopping from RGO to Fe3S4, improving the depth of the electrochemical reactions and facilitating the highly reversible lithiation/delithiation of Fe3S4. Thus, the resultant Fe3S4/RGO hybrid shows a highly reversible charge capacity of 1324 mA h g-1 over 275 cycles at a current density of 100 mA g-1, even retains 480 mA h g-1 over 500 cycles at 1000 mA g-1, which are much higher than reported values.

One-pot synthesis of bismuth silicate heterostructures with tunable morphology and excellent visible light photodegradation performances.

Construction of a heterostructure to prolong the life of electron-hole pairs is a very important approach to endow it with excellent photodegradation performances. Particularly, one-pot synthesis of heterostructures with the same component but different crystal structures to form a proper band gap is still challenging. Herein, bismuth silicate (BSO) heterostructures are synthesized using a one-pot hydrothermal approach without adding any other inorganic components. The crystal phase, morphology, surface state, and photochemical properties of the BSO materials are precisely tuned to fabricate two kinds of bismuth silicate heterostructures: rod-like Bi2SiO5/Bi12SiO20 and flower-like Bi2SiO5/Bi4Si3O12 heterostructures. Thanks to the two heterostructures and clean surface, the optimized BSO material exhibits a highly active photocatalytic performance with a remarkable cycling stability. It photodegrades Rhodamine B under visible light irradiation as fast as 15min with the reaction rate constants k and ks to be 0.399min-1 and 0.698min-1Lm-2, respectively, which is up to 189 times faster than reported.

K2 Mn4 O8 /Reduced Graphene Oxide Nanocomposites for Excellent Lithium Storage and Adsorption of Lead Ions.

Ion diffusion efficiency at the solid-liquid interface is an important factor for energy storage and adsorption from aqueous solution. Although K2 Mn4 O8 (KMO) exhibits efficient ion diffusion and ion-exchange capacities, due to its high interlayer space of 0.70 nm, how to enhance its mass transfer performance is still an issue. Herein, novel layered KMO/reduced graphene oxide (RGO) nanocomposites are fabricated through the anchoring of KMO nanoplates on RGO with a mild solution process. The face-to-face structure facilitates fast transfer of lithium and lead ions; thus leading to excellent lithium storage and lead ion adsorption. The anchoring of KMO on RGO not only increases electrical conductivity of the layered nanocomposites, but also effectively prevents aggregation of KMO nanoplates. The KMO/RGO nanocomposite with an optimal RGO content exhibits a first cycle charge capacity of 739 mA h g-1 , which is much higher than that of KMO (326 mA h g-1 ). After 100 charge-discharge cycles, it still retains a charge capacity of 664 mA h g-1 . For the adsorption of lead ions, the KMO/RGO nanocomposite exhibits a capacity of 341 mg g-1 , which is higher than those of KMO (305 mg g-1 ) and RGO (63 mg g-1 ) alone.

Growth of nickel silicate nanoplates on reduced graphene oxide as layered nanocomposites for highly reversible lithium storage.

The combination of active materials with electrically conductive carbon materials and their contact efficiency are crucial for improving the electrochemical performances of active materials. Here, nickel silicate (NiSiOx) nanoplates are planted in situ on the surface of reduced graphene oxide (RGO) nanosheets to form a two dimensional face-to-face nanocomposite of NiSiOx/RGO for lithium storage. The face-to-face structure enhances the contact efficiency of NiSiOx with RGO, and thus leads to a higher reversible capacity and better rate performance of the NiSiOx/RGO nanocomposite than both carbon nanotube (CNT)@NiSiOx nanocables and NiSiOx. The layered NiSiOx/RGO nanocomposite exhibits a high reversible specific capacity of 797 mA h g(-1), which is 62% and 806% higher than those of CNT@NiSiOx nanocables and NiSiOx alone, respectively.