Hollow Co2SiO4 microcube with amorphous structure as anode material for construction of high performance lithium ion battery

To solve the problem of large volume expansion of cobalt silicate electrode during cyclic process and low electric conductivity, Co₂SiO₄ with amorphous, porous and hollow structure is firstly designed to act as high performance lithium ion battery (LIB) anode. Compared with crystalline materials, the amorphous Co₂SiO₄ microcube could facilitate Li⁺ diffusion to enhance their performance of LIBs because of isotropic characteristics. Here, the amorphous Co₂SiO₄ hollow microcube (named as a-Co₂SiO₄ HC) was prepared by mild hydrothermal method with use of MnCO₃ microcube as hard-template. Benefitting from the advantages of such structure, Li⁺ diffusion rate was greatly accelerated and the volume expansion can be alleviated. The as-prepared amorphous Co₂SiO₄ hollow microcube as anode material of LIBs exhibited significantly improved electrochemical performance of 610 mAh g⁻¹ even after 380 cycles at 500 mAh g⁻¹ than their crystalline counterpart (only 280 mAh g⁻¹ retained after 380 cycles). This work is a good try to employ amorphous metal silicate in LIBs and simultaneously motivate the exploration of other amorphous materials for high performance LIBs, SIBs, catalysts, etc.     

Fullerene-like Re-Doped MoS2 Nanoparticles as an Intercalation Host with Fast Kinetics for Sodium Ion Batteries

Sodium ion batteries (SIBs) are considered as a promising alternative to threaten the reign of lithium ion batteries (LIBs) among various next-generation rechargeable energy storage systems, including magnesium ion, metal air, and metal sulfur batteries. Since both sodium and lithium are located in Group 1 of the periodic table, they share similar (electro)chemical properties with regard to ionization pattern, electronegativity, and electronic configuration; thus the vast number of compounds developed from LIBs can provide guidance to design electrode materials for SIBs. However, the larger ionic radius of the sodium cation and unique (de)sodiation processes may also lead to uncertainties in terms of thermodynamic or kinetic properties. Herein, we present the first construction of SIBs based on inorganic fullerene-like (IF) MoS₂ nanoparticles. Closed-shell-type structures, represented by C₆₀ fullerene, have largely been neglected for studies of alkali-metal hosting materials due to their inaccessibility for intercalating ions into the inner spaces. However, IF-MoS₂, with faceted surfaces, can diffuse sodium ions through the defective channels, thereby allowing reversible sodium ion intercalation/deintercalation. Interestingly, Re-doped MoS₂ showed good electrochemical performances with fast kinetics (ca. 74 mA h g⁻¹ at 20 C). N-type doping caused by Re substitution of Mo in IF-MoS₂ revealed enhanced electrical conductivity and an increased number of diffusion defect sites. Thus, chemical modification of fullerene-like structures through doping is proven to be a promising synthetic strategy to prepare improved electrodes.     

Binder-free multilayered SnO2/graphene on Ni foam as a high-performance lithium ion batteries anode

The reasonable structure construction of electrode materials with superior performance is desired for the new generation lithium ion batteries (LIBs). Herein, binder-free multilayered SnO₂/graphene (GN) on Ni foam was fabricated via a dip coating method. SnO₂ nanoparticles and GN were alternatively coated on Ni foam to form a sandwich-like structure. The wrapping of GN can raise the conductivity and keep the structural integrality of the binder-free material, preventing structure collapse arised from the volume expansion of SnO₂. Benefiting from the porous Ni foam framework and sandwich-like structure, the SnO₂/GN composite exhibited good rate performance and excellent cycle stability. High capacities of 708 and 609?mAh?g^?1 were achieved at rates of 1 and 2?A?g^?1. Besides, the SnO₂/GN electrode delivered a high capacity of 757?mAh?g^?1 after 500 cycles at 1?A?g^?1.     

Ultrafine SnO2 nanoparticles as a high performance anode material for lithium ion battery

In this paper, the ultrafine tin oxides (SnO₂) nanoparticles are fabricated by a facile microwave hydrothermal method with the mean size of only 14 nm. Phase compositions and microstructures of the as-prepared nanoparticles have been investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). It was found that the ultrafine SnO₂ nanoparticles are obtained to be the pure rutile-structural phase with the good dispersibility. Galvanostatic cycling and cyclic voltammetry results indicate that the first discharge capacity of the ultrafine SnO₂ electrode is 1196.63  mAh g⁻¹, and the reversible capacity could retain 272.63 mAh g⁻¹ at 100 mA g⁻¹ after 50 cycles for lithium ion batteries (LIBs). The excellent electrochemical performance of the SnO₂ anode for LIBs is attributed to its ultrafine nanostructure for providing active sites during lithium insertion/extraction processes. Pulverization and agglomeration of the active materials are effectively reduced by the microwave hydrothermal method.     

Free-standing SiOC/nitrogen-doped carbon fibers with highly capacitive Li storage

Silicon oxycarbide (SiOC) as a prospective electrode material for next-generation lithium ion batteries (LIBs) was restricted by the unsatisfactory discharge capacity and inflexibility used in flexible and wearable electronics. Herein, freestanding flexible SiOC/nitrogen-doped carbon fiber films are constructed through electrospinning process followed by carbonizing in NH₃ atmosphere. In this way, SiOC particles are tightly embedded in N-doped carbon fibers, forming a 3D conductive network to promote electron transport and faster reaction kinetics. The nitrogen dopants create more defects in carbon fibers matrix, which improve the electronic conductivity and electrochemical active sites of the electrodes. Owing to the above synergistic effect, SiOC/nitrogen-doped carbon fiber electrodes exhibit a high initial Coulombic efficiency of 73 % and a reversible remaining capacity of 595 mA h g⁻¹ at 200 mA g⁻¹ even after 200 cycles. The electrodes with good flexibility can successfully drive a light-emitting diode even when the package battery is bended to 180°.     

An ordered mesoporous network consisting of carbon-coated ultrasmall SnO2 nanoparticles with enhanced Lithium storage

An unique ordered mesoporous network consisting of carbon-coated SnO₂ nanoparticles (NPs) is developed by a facile self-assemble strategy via a solvethermal route in which employs N,N-dimethylformamide/H₂O as mixture solvent and polyvinyl pyrrolidone as barrier agent and carbon source. The SnO₂-NPs with an uniform dimension of ~5 nm are observed to interconnect with each other, and assemble into high-compact blocks where abundant mesopores with an average diameter of ~4 nm are found throughout the body. The carbon coating with a thickness of <1 nm are confirmed to exist on these SnO₂-NPs, which is of great importance to avoid the severe sintering that occurs in the case of bare SnO₂-NPs. Furthermore, the carbon coating plays roles in enhancing conductivity and keeping the active particles from being directly contacted with electrolyte, and thus contributes to enhanced reversible capacity of 949 mAh g⁻¹ and improved initial Coulombic efficiency. The composite electrode with a high tap density of 2.0 g cm⁻³ exhibits substantially elevated electrochemical performances, such as a charge capacity of 565 mAh g⁻¹ vs 223 mAh g⁻¹ of common SnO₂-NPs after 60 cycles and greatly improved rate capability, indicating the promising applications of this advanced micro-nano architecture for next-generation lithium-ion batteries.     

Facile fabrication of porous NiMoO4@C nanowire as high performance anode material for lithium ion batteries

Herein, porous NiMoO₄@C nanowire is purposefully synthesized using oleic acid as carbon source, and further evaluated as high performance anode material for Li-ion batteries (LIBs). Compared with the pure NiMoO₄, porous NiMoO₄@C nanowire exhibits high reversible charge/discharge specific capacity, excellent cycle stability and preeminent rate capability. A stable reversible lithium storage capacity of 975 mAh g⁻¹ can still be maintained after 100 cycles at 200 mA g⁻¹. When the current density decreases back from 3000 mA g⁻¹ to 100 mA g⁻¹, a high discharge specific capacity of 884 mAh g⁻¹ is recovered. The porous structure and carbon layers can enhance the electronic transmission and structural stability, shorten the path lengths for ion and electron transport, and provide a mechanical buffer space to accommodate the volume expansion/contraction during the repeated Li⁺ insertion/extraction processes. All the results highlight that the porous NiMoO₄@C nanowire composite would be a promising candidate for high performance anode material of LIBs owing to its excellent electrochemical properties.     

NiFe-NiFe2O4/rGO composites: Controlled preparation and superior lithium storage properties

Binary transition-metal oxides with spinel structure have great potential as advanced anode materials for lithium-ion batteries (LIBs). Herein, NiFe-NiFe₂O₄/ reduced graphene oxide (rGO) composites are obtained via a facile cyanometallic framework precursor strategy to improve the lithium storage performance of NiFe₂O₄. In the composites, NiFe-NiFe₂O₄ nanoparticles with adjustable mass ratios of NiFe₂O₄ to NiFe alloy are homogeneously deposited on rGO sheets. As anode material for LIBs, the optimized NiFe-NiFe₂O₄/rGO composite displays remarkably enhanced lithium storage performance with an initial specific capacity as high as 1362 mAh g⁻¹ at 0.1 A g⁻¹ and a decent capacity retention of ca. 80% after 130 cycles. Besides, the composite delivers a reversible capacity of 550 mAh g⁻¹ at 1 A g⁻¹ after 300 cycles. During the charge–discharge cycles, the aggregation of the NiFe-NiFe₂O₄ nanoparticles and the structural collapse of the electrode can be well alleviated by rGO sheets. Moreover, the conductivity of the electrode can be significantly improved by the well-conductive NiFe alloy and rGO sheets. All these contribute to the improved lithium storage performance of NiFe-NiFe₂O₄/rGO composites.     

Cellulose acetate-based separators prepared by a reversible acetylation process for high-performance lithium-ion batteries

Lithium-ion batteries (LIBs) are one of the most widely used technologies for various applications. However, polyolefin separators can hardly meet the needs of the development of LIBs due to the poor heat shrinkage and bad wettability with the electrolyte. Herein, a cellulose acetate (CA)-based separator is developed by blending with cellulose nanocrystals (CNCs) using a simple reversible acetylation process. This separator exhibits inherent thermal stability and improved ionic conductivity due to the finger-like and sponge-like porous structure. Moreover, the discharge capacity of the separator with a CNC loading of 3% remains at 132.9 mA h g⁻¹ when the rate reverts to 0.2 C and the capacity retention reaches 89.5% after 50 cycles. Therefore, the obtained CA-based separators can be a competitive candidate for high-performance LIBs and point the way to sustainable development.     

FeS2@TiO2 nanorods as high-performance anode for sodium ion battery

Sodium-ion battery (SIB) is an ideal device that could replace lithium-ion battery (LIB) in grid-scale energy storage system for power because of the low cost and rich reserve of raw material. The key challenge lies in developing electrode materials enabling reversible Na⁺ insertion/desertion and fast reaction kinetics. Herein, a core-shell structure, FeS₂ nanoparticles encapsulated in biphase TiO₂ shell (FeS₂@TiO₂), is developed towards the improvement of sodium storage. The diphase TiO₂ coating supplies abundant anatase/rutile interface and oxygen vacancies which will enhance the charge transfer, and avoid severe volume variation of FeS₂ caused by the Na⁺ insertion. The FeS₂ core will deliver high theoretical capacity through its conversion reaction mechanism. Consequently, the FeS₂@TiO₂ nanorods display notable performance as anode for SIBs including long-term cycling performance (637.8 mA·h·g⁻¹ at 0.2 A·g⁻¹ after 300 cycles, 374.9 mA·h·g⁻¹ at 5.0 A·g⁻¹ after 600 cycles) and outstanding rate capability (222.2 mA·h·g⁻¹ at 10 A·g⁻¹). Furthermore, the synthesized FeS₂@TiO₂ demonstrates significant pseudocapacitive behavior which accounts for 90.7% of the Na⁺ storage, and efficiently boosts the rate capability. This work provides a new pathway to fabricate anode material with an optimized structure and crystal phase for SIBs.     

Binder-free carbon-coated TiO2@graphene electrode by using copper foam as current collector as a high-performance anode for lithium ion batteries

Anatase TiO₂ is widely used in lithium ion batteries (LIBs) due to its excellent safety and excellent structural stability. However, due to the poor ion and electron transport and low specific capacity (335 mAh g⁻¹) of TiO₂, its application in LIBs is severely limited. For the first time, we report a binder-free, carbon-coated TiO₂@graphene hybrid by using copper foam as current collector (TG-CM) to enhance the ionic and electronic conductivity and increase the discharge specific capacity of the electrode material without adding conductive carbon (such as super P, etc.) and a binder (such as polyvinylidene fluoride (PVDF), etc.). When serving as an anode material for LIBs, TG-CM displays excellent electrochemical performance in the voltage range of 0.01–3.0 V. Moreover, the TG-CM hybrid delivers a high reversible discharge capacity of 687.8 mAh g⁻¹ at 0.15 A g⁻¹. The excellent electrochemical performance of the TG-CM hybrid is attributed to the increased lithium ion diffusion rate due to the introduction of graphene and amorphous carbon layer, and the increased contact area between the active material and electrolyte, and small resistance with copper foam as the current collector without an additional binder (PVDF) and conductivity carbon (super P).     

Carbon coated porous tin peroxide/carbon composite electrode for lithium-ion batteries with excellent electrochemical properties

A porous tin peroxide/carbon (SnO₂/C) composite electrode coated with an amorphous carbon layer is prepared using a facile method. In this electrode, spherical graphite particles act as supporter of electrode framework, and the interspace among particles is filled with porous amorphous carbon derived from decomposition of polyvinylidene fluoride and polyacrylonitrile. SnO₂ nanoparticles are uniformly embedded in the porous amorphous carbon matrix. The pores in amorphous carbon matrix are able to buffer the huge volume expansion of SnO₂ during charge/discharge cycling, and the carbon framework can prevent the SnO₂ particles from pulverization and re-aggregation. The carbon coating layer on the outermost surface of electrode can further prevent porous SnO₂/C electrode from contacting with electrolyte directly. As a result, the repeated formation of solid electrolyte interface is avoided and the cycling stability of electrode is improved. The obtained SnO₂/C electrode presents an initial coulombic efficiency of 77.3% and a reversible capacity of 742 mA h g⁻¹ after 130 cycles at a current density of 100 mA g⁻¹. Furthermore, a reversible capacity of 679 mA h g⁻¹ is obtained at 1 A g⁻¹.     

Synthesis and characterization of GaNb11O29@C for high-performance lithium-ion battery

The GaNb₁₁O₂₉ shows an open Wadsley-Roth shear structure, which is of great benefit to store ions in rechargeable batteries. In this work, we successfully synthesize GaNb₁₁O₂₉@C via a simple solid-state reaction method combined with carbon-coating modification. As anode for LIBs, the as-synthesized GaNb₁₁O₂₉@C sample exhibits wonderful electrochemical behaviors. It exhibits high reversible capacity (227.3 mA h g⁻¹), outstanding rate capability (58.91% retention at 700 mA g⁻¹) and excellent long cycle performance (0.036% capacity decay per cycle). The enhancement of diffusion kinetics and rate performance assigns to the increased surface reaction activity and electrical conductivity. The open and stable crystal framework structure guarantees rapid lithium-ion migration, excellent rate performance and long cycle performance. These results tell that GaNb₁₁O₂₉@C is promising anode material for the application in advanced LIBs.     

Rational Design of 3D Honeycomb-Like SnS<Subscript>2</Subscript> Quantum Dots/rGO Composites as High-Performance Anode Materials for Lithium/Sodium-Ion Batteries

Structure pulverization and poor electrical conductivity of metal dichalcogenides result in serious capacity decay both in lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs). To resolve the above problems, a combination of metal dichalcogenides with conductive scaffolds as high-performance electrode materials has aroused tremendous interest recently. Herein, we synthesize a 3D honeycomb-like rGO anchored with SnS₂ quantum dots (3D SnS₂ QDs/rGO) composite via spray-drying and sulfidation. The unique 3D-ordered honeycomb-like structure can confine the volume change of SnS₂ QDs in the lithiation/delithiation and sodiation/desodiation processes, provide enough space for electrolyte reservoirs, promote the conductivity of the SnS₂ QDs, and improve the electron transfer. As a result, the 3D SnS₂ QDs/rGO composite electrode delivers a high capacity and long cycling stability (862 mAh/g for LIB at 0.1 A/g after 200 cycles, 233 mAh/g for SIB at 0.5 A/g after 200 cycles). This study provides a feasible synthesis route for preparing 3D-ordered porous networks in varied materials for the development of high-performance LIBs and SIBs in future.     

NiCo2O4 nanosheets and nanocones as additive-free anodes for high-performance Li-ion batteries

Development of novel electrode materials with high energy and power densities for lithium-ion batteries (LIBs) is the key to meet the demands of electric vehicles. Transition metal oxides that can react with large amounts of Li⁺ for electrochemical energy storage are considered promising anode materials for LIBs. In this work, NiCo₂O₄ nanosheets and nanocones on Ni foam have been synthesized via general hydrothermal growth and low-temperature annealing treatment. They exhibit high rate capacities and good cyclic performance as LIB anodes owing to their architecture design, which reduces ion and electron transport distance, expands the electrode–electrolyte contact, increases the structural stability, and buffers volume change during cycles. Notably, NiCo₂O₄ nanosheets deliver an initial capacity of 2239 mAh g⁻¹ and a rate capacity of 964 mAh g⁻¹ at current densities of 100 and 5000 mA g⁻¹, respectively. The corresponding values of nanocones are 1912 and 714 mAh g⁻¹. Hence, the as-synthesized NiCo₂O₄ nanosheets and nanocones, which are carbon-free and binder-free with higher energy densities and stronger connections between active materials and current collectors for better stability, are promising for use in advanced anodes for high-performance LIBs.     

Boosted sodium storage of GeS2/GeO2/ZnS composite via heterostructure engineering

Transition metal dichalcogenides exhibit tremendous potential for sodium ion batteries (SIBs), owing to the outstanding specific capacity and aboundant reserves. However, the large ionic radius of sodium and poor conductivity often result in the fast decaying performance and inferior reaction kinetics. Herein, the GeS₂/GeO₂/ZnS@rGO (GGZ/C) ternary metal-based composite is fabricated as an anode material for SIBs. Notably, the GGZ/C composite is derived from the phase transformation of Zn₂GeO₄ precursor, which is beneficial for the heterostructure engineering. In this hierarchical structure, the metal phases ZnS and GeO₂ are used to form the heterogeneous framework, while graphene is applied to build a conductive network and anchor the host nanoparticles. Therefore, the great Na⁺ diffusion channels are achieved by the rational design of the huge exquisite interfaces among the heterogeneous mixed phases. Notably, it can almost completely relieve the volume expansion and restrain the internal stress of GGZ/C composite, providing the excellent structural tolerance. As expected, the GGZ/C composite exhibits excellent rate capability, with an impressive reversible capacity of 548 mAh g⁻¹ at a high rate of 5.0 A g⁻¹. Meanwhile, the GGZ/C also displays outstanding cycling performance with a specific capacity of 519 mAh g⁻¹ after 650 cycles at high rate of 5.0 A g⁻¹. This strategy offers the inspiration for rational heterostructure engineering for the energy storage materials with excellent reversible capacity and large volume variation.     

Synthesis of SnO2@MnO2@graphite nanosheet with high reversibility and stable structure as a high-performance anode material for lithium-ion batteries

In this study, SnO₂@MnO₂@graphite (SMG) anode material is prepared via a facile ball-milling approach combined with hydrothermal treatment. SnO₂ and MnO₂ nanoparticles are evenly dispersed on numerous sheet-like graphite. MnO₂ can not only play a catalytic role for facilitating the conversion reaction of Sn/Li₂O to SnO₂, but also as a barrier to impede the coarsening of Sn in the composite. Meanwhile, graphite nanosheets could serve as an ideal volume expansion buffer and good electron conductor. Consequently, the SMG anode delivers superior reversible capacity of 1048.5 mAhg⁻¹, ideal rate capability of 522.2 mAhg⁻¹ at 5.0 A g^-1 and stable long-life cyclic performance of 814.8 mAhg⁻¹ at 1.0 A g^-1 after 1000 cycles. This result indicates that the incorporation of MnO₂, graphite nanosheet and SnO₂ have a great potential in enhancing the performance of SnO₂-based anode for battery applications.     

Densely-stacked N-doped mesoporous TiO2/carbon microsphere derived from outdated milk as high-performance electrode material for energy storages

Spherical N-doped mesoporous TiO₂/C (MTC) composite micro-particles are produced by spray drying (SD) and carbonization process. The particle size of MTC microsphere is between 2 and 3.4?µm, and the N-doped amorphous C around TiO₂ could provide a conductive matrix, and buffer the volume change. When evaluated as electrodes for Li-ion batteries (LIBs) and Li-S batteries (LSBs), the MTC microsphere exhibits relatively high discharge-voltage plateau, excellent capacity retention and rate capability. As anode for LIBs, after 200 cycles, a reversible capacity more than 230?mA?h?g^?1 can achieved at 1?C. And for LSBs, a specific capacity of 1317.7?mA?h?g^?1 at 1?C and the capacity retention of 73.8% after 500 cycles. The superior electrochemical performance is ascribed to robust scaffolding architecture and conductive N-doped carbon matrix. The excellent electrochemical performance and process ability of the MTC microspheres make them very attractive as electrode materials for use in high rate battery application.     

Characterization of vacuum-annealed TiNb2O7 as high potential anode material for lithium-ion battery

Electrochemical properties of mixed titanium-niobium oxide TiNb₂O₇ (TNO) synthesized via vacuum annealing as high potential anode material for lithium-ion batteries were investigated. Crystal structure, size, and morphology are nearly independent of the annealing atmosphere for starting materials but the color of vacuum-annealed TNO (TNO-V) is dark blue while white for the air-annealed one (TNO-A). X-ray photoelectron spectroscopy analysis also indicated that Ti⁴⁺ and Nb⁵⁺ in TNO are partially reduced into Ti³⁺ and Nb⁴⁺ due to the introduction of oxygen vacancy. Electronic conductivity for TNO-V was around 10⁻³ S cm⁻¹ at room temperature and much higher than that for TNO-A (=10⁻¹¹ S cm⁻¹). In electrochemical testing, both TNO-A and TNO-V electrodes showed reversible capacity of 260-270 mAh g⁻¹ at low current density of 0.5 mA cm⁻², while at higher current density of 5.0 mA cm⁻², TNO-V electrode retained higher reversible capacity of 140 mAh g⁻¹ than that for TNO-A electrode (=80 mAh g⁻¹). The enhancement of intrinsic electronic conductivity greatly contributes to improve the rate performance of TNO.     

NiSe2 encapsulated in N-doped TiN/carbon nanoparticles intertwined with CNTs for enhanced Na-ion storage by pseudocapacitance

Transitional metal selenides are considered as potential anode candidates for sodium-ion batteries (SIBs) because of their relatively high theoretical capacity and environmental benign. However, the large volume change derived from the conversion reaction and the sluggish kinetics due to the inherent low electrochemical conductivity hinder their practical application. Herein, composite materials of NiSe₂ encapsulated in nitrogen-doped TiN/carbon nanoparticles with carbon nanotubes (CNTs) on the surface (NiSe₂@N-TCP/CNTs) are fabricated via pyrolysis and selenization processes. In this composite, TiN inside the carbon matrix can enhance the conductivity and structural stability. CNTs that are in-situ grown on the surface not only further enhance the conductivity of the composites, but also offer sufficient space to buffer the volume expansion and alleviate serious aggregation of NiSe₂ nanoparticles. Benefit from these merits, the NiSe₂@N-TCP/CNTs showed a lower charge transfer resistance and a faster Na⁺ diffusion rate than materials without growing CNTs. When used as the anode of SIBs, the NiSe₂@N-TCP/CNTs electrode delivered a reversible capacity of 344.0 mAh g^?1 after 1000 cycles at 0.2 A g^?1, and still maintained at 272.7 mAh g^?1 even at a high current density of 2 A g^?1. The remarkable electrochemical performance is mainly attributed to the special designed hierarchical structures and pseudocapacitance sodium storage behavior.