Improved Lithium Storage Research Articles

Spectroscopic investigations on the origin of the improved performance of composites of nanoparticles/graphene sheets as anodes for lithium ion batteries

Composites of nanoparticles/graphene sheets show an improved lithium storage capacity and cycling stability compared to bare graphene sheets (GSs). They are therefore considered as one of the promising candidates of anode materials for portable electrochemical energy storage devices requiring lightweight and ultrathin batteries. The practical application of these materials relies on the in-depth understanding of the origin of their improved performance. In this work, a composite of silver nanoparticles and graphene sheets (Ag/GSs) has been used as a model material to investigate the origin of the improved electrochemical performance by impedance, ex situ XPS and in situ Raman spectroscopy. We found that the Ag/GSs composite electrode has higher electrical conductivity than GSs. AgLix alloy was formed during the lithiation. Insertion of Ag nanoparticles into the interlayers between graphene sheets reduced the mean number of graphene stacking layers in the composite and provided a better site accessibility for Li+ insertion. Comparative in situ Raman measurements of them showed a completely reversible structural evolution of graphene sheets in Ag/GSs during the first lithiation/de-lithiation process, while for GSs the structural stability was worse. In combination, these effects are favorable for improving the reversible capacity and retaining the cycle stability of the Ag/GSs composite.

A robust strategy for stabilizing SnO2: TiO2-supported and carbon-immobilized TiO2/SnO2/C composite towards improved lithium storage

With a much higher theoretical capacity than that of graphite anodes, SnO2 has attained great attention as a potential anode material for next-generation lithium-ion batteries. However, it's practical application yet be impeded by such disadvantages of poor conductivity and terrible structure stability during repeated discharge/charge process. Herein, a unique TiO2/SnO2/C hybrid (TiO2 SS@SnO2@C) consist of one-dimensional TiO2 nanobelts, zero-dimensional SnO2 nanoparticles and conformal carbon coating has been fabricated based on a strategy of synergistic effect of components with different dimensional nanostructures, which can provide improved electrochemical kinetic and outstanding structure stability for the TiO2 SS@SnO2@C. As a result, the TiO2 SS@SnO2@C is able to exhibit outstanding lithium storage performance as an anode material, delivering capacities of 904.9 and 492.4 mAhh g−1 after even 400 cycles at 200 and even 1000 mA g−1, respectively. It is demonstrated that the synergistic effect of these components is responsible for thus outstanding electrochemical performance.

Large‐Scale Fabrication of Core–Shell Structured C/SnO2 Hollow Spheres as Anode Materials with Improved Lithium Storage Performance

Due to the high theoretical capacity as high as 1494 mAh g-1 , SnO2 is considered as a potential anode material for high-capacity lithium-ion batteries (LIBs). Therefore, the simple but effective method focused on fabrication of SnO2 is imperative. To meet this, a facile and efficient strategy to fabricate core-shell structured C/SnO2 hollow spheres by a solvothermal method is reported. Herein, the solid and hollow structure as well as the carbon content can be controlled. Very importantly, high-yield C/SnO2 spheres can be produced by this method, which suggest potential business applications in LIBs field. Owing to the dual buffer effect of the carbon layer and hollow structures, the core-shell structured C/SnO2 hollow spheres deliver a high reversible discharge capacity of 1007 mAh g-1 at a current density of 100 mA g-1 after 300 cycles and a superior discharge capacity of 915 mAh g-1 at 500 mA g-1 after 500 cycles. Even at a high current density of 1 and 2 A g-1 , the core-shell structured C/SnO2 hollow spheres electrode still exhibits excellent discharge capacity in the long life cycles. Consideration of the superior performance and high yield, the core-shell structured C/SnO2 hollow spheres are of great interest for the next-generation LIBs.

Design and fabrication of N-doped graphene decorated LiFePO4@C composite as a potential cathode for electrochemical energy storage

Olivine-structured LiFePO4@C nanoparticles grown on N-doped graphene (NG) sheets have been fabricated by using a simple sol-gel method with post calcinations. During the synthesis process, both the carbon film and NG sheets can inhibit the growth of LiFePO4 particles. Meanwhile, the constructed conductive network between the NG and carbon film can greatly enhance the electronic conductivity of LiFePO4 material. These unique properties lead to markedly improved lithium storage performance. The NG-decorated LiFePO4@C (NG-LiFePO4@C) composite presents high specific capacity (163.1mAhg−1, 0.1C) and excellent rate capability (118.6mAhg−1, 10C). Therefore, this NG-LiFePO4@C composite can be regarded as a potential electrode for electrochemical energy storage.

Carbon sphere@Co9S8 yolk-shell structure with good morphology stability for improved lithium storage performance

The poor electronic conductivity and huge volume expansion of cobalt sulfides upon cycling would lead to their poor electrochemical performances for Lithium-ion batteries. Here, we rationally design a yolk-shell carbon sphere@Co9S8 (C@CS) composite, which demonstrates improved kinetics and excellent morphology stability during cycling. This structure can keep Co9S8 shell from collapse and aggregation. After cycling, a layer of thin solid electrolyte interphase is coated on the Co9S8 shells and prevented them from dissolving in electrolyte, which is helpful for the electrochemical performances. As a result, the C@CS electrodes exhibit good lithium storage performances, including excellent cyclic stability up to 300 cycles at 1000 and 2000 mA g−1 and high-rate property of 4000 mA g−1 with a capacity of 489 mA h g−1.

Tailored synthesis of monodispersed nano/submicron porous silicon oxycarbide (SiOC) spheres with improved Li-storage performance as an anode material for Li-ion batteries

A spherical silicon oxycarbide (SiOC) material (monodispersed nano/submicron porous SiOC spheres) is successfully synthesized via a specially designed synthetic strategy involving pyrolysis of phenyltriethoxysilane derived pre-ceramic polymer spheres at 900 °C. In order to prevent sintering of the pre-ceramic polymer spheres upon heating, a given amount of hollow porous SiO2 nanobelts which are separately prepared from tetraethyl orthosilicate with CuO nanobelts as templates are introduced into the pre-ceramic polymer spheres before pyrolysis. This material is investigated as an anode for lithium-ion batteries in comparison with the large-size bulk SiOC material synthesized under the similar conditions but without hollow SiO2 nanobelts. The maximum reversible specific capacity of ca. 900 mAh g−1 is delivered at the current density of 100 mA g−1 and ca. 98% of the initial capacity is remained after 100 cycles at 100 mA g−1 for the SiOC spheres material, which are much superior to the bulk SiOC material. The improved lithium storage performance in terms of specific capacity and cyclability is attributed to its particular morphology of monodisperse nano/submicron porous spheres as well as its modified composition and microstructure. This SiOC material has higher Li-storage activity and better stability against volume expansion during repeated lithiation and delithiation cycling.

Hydrothermal synthesis and high electrochemical performance of ordered mesoporous Co/CMK-3 nanocomposites

A novel ordered mesoporous Co/CMK-3 nanocomposites were successfully fabricated via a facile hydrothermal method. XRD patterns affirmed that the CoCl2 entirely reduced to metal Co. Cobalt particles were well-dispersed and embedded in the mesochannels of the CMK-3 according to the nitrogen adsorption-desorption technique and transmission electron microscopy (TEM) images. Electrochemical test shows that cobalt nanoparticle can significantly promote the electrochemical properties of CMK-3 leading to a remarkable enhancement of the reversible capacity, cyclic stability, and rate capacity. The Co/CMK-3 nanocomposites were delivering a high reversible capacity of 674 mAh g−1 at the current density of 50 mA g−1 after 50 cycles, which was much higher than that of original CMK-3 (400 mAh g−1). The Co/CMK-3 nanocomposites also demonstrate an excellent rate capability. The improved lithium storage properties of ordered Co/CMK-3 nanocomposites can be attributed to the CMK-3 that could restrain the aggregation of Co nanoparticles, the large surface area of the mesopores in which the Co nanoparticles are formed, as well as presence of Co which played the role of catalyst could promote the lithium storage reaction.

Mesoporous spinel ferrite composite derived from a ternary MgZnFe-layered double hydroxide precursor for lithium storage

Layered double hydroxides (LDHs), also known as hydrotalcite-like anionic clays, are very convenient precursors with a tunable flexibility toward multifunctional nanomaterials, especially in energy storage. Typical methods to improve lithium storage are to introduce additional or self-generating carbonaceous supports to LDH-derived transition metal oxides as anode nanomaterials which can host lithium mainly though a conversion mechanism. Here, we describe a preparation of mesoporous spinel ferrite composite (MgFe2O4/ZnFe2O4) for lithium storage, which is assisted by a combined conversion and alloying mechanism. The composite is derived by a thermal decomposition of a scalablely produced single-resource precursor of ternary Mg2+Zn2+Fe3+-layered double hydroxide (Mg2+Zn2+Fe3+-LDH), and subsequent selective etching. Electrochemical test shows that the electrode delivers an exceptional electrochemical performance, i.e., a reversible capacity of 1190 mA h g−1 after 100 cycles at 100 mA g−1, and, in particular, a reversible capacity of 981 mA h g−1 at 500 mA g−1 after 330 cycles, as well as a reversible capacity of 541 mA h g−1 at 2000 mA g−1 after 1000 cycles. The high electrochemical performance could be attributed to the following features: the combined alloying and conversion mechanisms of ZnFe2O4, synergistic MgFe2O4, and slight-content MgO as a non-active matrix, as well as an appropriate specific area and mesoporous size distribution. Our results show that the cation-tunable LDH precursor-derived synthesis route might be an alternative to prepare multiple-component composites of spinel ferrites and transition metal oxides.

Fabrication of novel hetero-nanostructure of SnO2@TiO2@C for improved lithium storage

Herein, a novel hetero-nanostructure of SnO2@TiO2@C has been fabricated by an elaborate approach. In the SnO2@TiO2@C, porous SnO2 quasi-nanocubes are double protected by ultrafine TiO2 nanorods and carbon coating. As anodes for lithium-ion batteries, the as-prepared SnO2@TiO2@C exhibit improved lithium storage and rate performance. It is demonstrated that the novel hetero-nanostructure should be responsible for thus improved performance.

Embedding ZnSe nanodots in nitrogen-doped hollow carbon architectures for superior lithium storage

Transition metal chalcogenides represent a class of the most promising alternative electrode materials for high-performance lithium-ion batteries (LIBs) owing to their high theoretical capacities. However, they suffer from large volume expansion, particle agglomeration, and low conductivity during charge/discharge processes, leading to unsatisfactory energy storage performance. In order to address these issues, we rationally designed three-dimensional (3D) hybrid composites consisting of ZnSe nanodots uniformly confined within a N-doped porous carbon network (ZnSe ND@N-PC) obtained via a convenient pyrolysis process. When used as anodes for LIBs, the composites exhibited outstanding electrochemical performance, with a high reversible capacity (1,134 mA·h·g−1 at a current density of 600 mA·g−1 after 500 cycles) and excellent rate capability (696 and 474 mA·h·g−1 at current densities of 6.4 and 12.8 A·g−1, respectively). The significantly improved lithium storage performance can be attributed to the 3D architecture of the hybrid composites, which not only mitigated the internal mechanical stress induced by the volume change and formed a 3D conductive network during cycling, but also provided a large reactive area and reduced the lithium diffusion distance. The strategy reported here may open a new avenue for the design of other multifunctional composites towards high-performance energy storage devices.

A Hierarchical, Nanofibrous, Tin‐Oxide/Silicon Composite Derived from Cellulose as a High‐Performance Anode Material for Lithium‐Ion Batteries

AbstractA hierarchical nanofibrous tin‐oxide/silicon composite with tin oxide nanoparticles anchored on the silicon nanofiber surface is fabricated employing natural cellulose substance (ordinary filter paper) as structural template. Tin oxide gel is deposited uniformly onto the surface of the silicon nanofibers that prepared by magnesiothermic reduction of the silica replica of the filter paper, and thereafter, the as‐prepared tin‐oxide−gel/silicon nanocomposite is calcined in argon atmosphere to yield the tin‐oxide/silicon nanocomposite. The resulted tin‐oxide/silicon nanocomposite possesses a hierarchical network structure that inherited from the initial cellulose substance. When the nanocomposite is evaluated as an anode material in lithium‐ion batteries, it exhibits superior lithium storage properties compared with the pure silicon nanofiber and tin oxide powder matters. For such a nanocomposite with 58.8 wt% tin oxide content delivers a specific reversible capacity of 547.8 mAh g−1 after 150 discharge/charge cycles at 100 mA g−1. The improved lithium storage performances are attributed to the unique three‐dimensional hierarchical porous network structure of the nanocomposite, high dispersed fine tin oxide nanoparticles on the silicon nanofiber surface, as well as the synergistic effects between the silicon nanofibers and the tin oxide nanoparticles on the lithium storage.

Laser in-situ synthesis of SnO2/N-doped graphene nanocomposite with enhanced lithium storage properties based on both alloying and insertion reactions

This paper reported a SnO2/N-doped graphene nanocomposite (SnO2/N-Gr) electrode which was prepared by a laser in-situ synthesis method. When demonstrated as anodes for lithium storage, the SnO2/N-Gr electrode showed improved lithium storage capacities and rate performance. In details, a reversible capacity of 830mAhg−1 was obtained after 300 cycles at a current density of 300mAg−1, and when the current density increased up to 3Ag−1, the SnO2/N-Gr electrode revealed a high reversible capacity of 600mAhg−1. It was proven that the excellent electrochemical performance mainly related to a hybrid lithium storage mechanism which combined with alloying and insertion reactions. By introducing huge numbers of micropores and defects on graphene sheets, N-doping increased the number of hosts for lithium insertion and enhanced the Li+ diffusion rate in graphene sheets, so both of lithium storage capacities and rate performance were effectively improved. The SnO2/N-Gr electrode had a short preparing procedure and good electrochemical performance, which hold potential for development of next generation lithium ion batteries with high specific capacities and good rate performance.

Formation of Porous Cu‐Doped CoSe2 Connected by Nanoparticles for Efficient Lithium Storage

AbstractA porous structure is widely considered as an efficient way to improve lithium storage performance. In this paper, a novel porous Cu‐doped CoSe2 product is prepared by annealing a ZIF‐67 precursor and Se powder. This Cu‐doped CoSe2 sample is composed of interconnected nanoparticles. The average particle size of the nanoparticles is around 80 nm. When evaluated as anode materials for lithium‐ion batteries, this porous structure could effectively shorten the charge‐transport path and accommodate volume expansion during charge/discharge cycling. Therefore, porous Cu‐doped CoSe2 manifests both a superior rate capacity of about 747 mAh/g at 5 A/g and a stable cycling capacity of about 807 mAh/g for 200 cycles.

Elaborate strategy for preparing Li4Ti5O12-based anode materials with significantly improved lithium storage: TiO2 nanodots in-situ decoration and hierarchical structure construction

Spinel Li4Ti5O12 (LTO) has attracted extensive attention as potential anode materials for power lithium-ion batteries due to its outstanding structural stability and remarkable safety. However, it's practical application yet be limited by such disadvantages of dissatisfied specific capacity, poor electron conductivity and low lithium-ion diffusion coefficient. Thus, design and preparation of LTO anodes with desirable performance is still a challenge. Herein, we have successfully and greatly improved the performance of LTO anodes, in terms of rate capability, life and specific capacity in particular via dot-to-face anatase TiO2in-situ decoration and hierarchical structure construction under a facile approach (directly using the tetrabutyl titanate as titanium source instead of specially prepared titanium oxide precursors). The as-prepared LTO-based anode (denoted as T-LTO) delivers an ultra-high reversible specific capacity of 196.5 mAh g−1 after 300 cycles at 20 mA g−1, and superior rate performance and even ultra-long life of more than 145.8 mAh g−1 at 28.5C between 1.0 and 3.0 V. The achieved outstanding electrochemical performance largely surpasses that of reportedly state-of-the-art LTO-based anode materials. This work may open up a broader vision into developing advanced LTO-based anode materials for lithium-ion batteries.

Facile preparation of quasi-coral-like SnOx@C for improved lithium storage

Herein, a quasi-coral-like nanostructure of SnO2/SnO@C composite (SnOx@C) has been prepared by a facile one-pot hydrothermal and subsequent carbonization strategy. This interesting architecture of ultrasmall SnOx nanoparticles embedded into quasi-coral-like carbon matrix can not only accommodate the volume change of SnO2, but also improve the conductivity of whole SnOx@C electrode. In consequence, the SnOx@C exhibits outstanding lithium storage.

Ultrathin amorphous TiO2 nanofilm-coated graphene with superior electrochemical performance for lithium-ion batteries

As a novel anode material for lithium-ion batteries, graphene has a higher theoretical capacity than graphite. However, the practical application of graphene suffers from a low coulombic efficiency and poor cycle stability due to the unstable solid electrolyte interphase layer. In this work, ultrathin amorphous TiO2 nanofilm-coated graphene is fabricated by controlled hydrolysis of tetrabutyl titanate on the surface of graphene, and shows superior cycle and rate performance compared to uncoated graphene because amorphous TiO2 nanofilms can prevent the detachment of graphene nanosheets and avoids the formation of thick and unstable solid-electrolyte interphase layers during cycling. Moreover, the electrochemical performance of TiO2-coated graphene can be further improved by controllable calcination of TiO2-coated graphene under a N2 atmosphere. The produced porosity of TiO2 nanofilms after calcination can improve both Li+ and electron transport, leading to the further improved lithium storage performance of graphene. This novel synthesis strategy may be employed in other graphene-based anode materials for high-performance lithium-ion batteries and other electrochemical devices.

Co 3 O 4 microtubules derived from a biotemplated method for improved lithium storage performance

Abstract A simple and effective biotemplated method is applied to fabricate porous microtubular cobalt oxide by infiltration of cotton fiber with a cobalt nitrate solution, followed by annealing at 500 °C in air. The as-obtained Co 3 O 4 have been characterized by: X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM), N 2 adsorption and desorption measurements, and thermal analysis (TG). According to these results, the as-prepared Co 3 O 4 display a perfect tubular morphology and mesoporous features. The electrochemical performance of the as-obtained sample was studied for use as a lithium-ion battery anode material by cyclic voltammetry (CV), and charge-discharge and electrochemical impedance spectroscopy (ESI) measurements. Compared to bulk Co 3 O 4 and previously reported nanostructured Co 3 O 4 electrodes, mesoporous microtubular Co 3 O 4 show an improved lithium storage properties, which can be attributed to their unique morphology, large specific surface area and mesoporous feature.

An elaborate strategy for fabricating one-dimensional quasi-hollow nanostructure of tin dioxide@carbon composite with improved lithium storage performance

The current research priorities about tin dioxide-based anodes mainly focus on improvement of structure stability and rate performance due to the intrinsic issues of huge volume change and poor conductivity of tin dioxide materials. Herein, it is demonstrated that a one-dimensional quasi-hollow nanostructure of tin dioxide@carbon (SnO2@C) composite with improved electrochemical performance can be prepared by an elaborately simplified approach. It is worthy of noting that a proposed hydrothermal treatment plays an indispensable role in formation of this SnO2@C composite. As a promising anode for lithium-ion batteries, this as-prepared versatile nanostructure of SnO2@C composite combining advantages of one-dimension, hollow-confine and carbon coating able to exhibit high capacities of 749.3 and 549.8 mAh g−1 after 100 cycles respectively at 200 and even 1000 mA g−1, as well as superior rate properties. The well-designed versatile nanostructure should be responsible for thus outstanding performance.

Achievement of significantly improved lithium storage for novel clew-like Li 4 Ti 5 O 12 anode assembled by ultrafine nanowires

Spinel lithium titanate (Li4Ti5O12) has attracted extensive attention by virtue of its inherent features of zero strain and high operating potential, which results in outstanding structural stability and remarkable safety as anode materials for lithium-ion batteries. But, there are two issues of low specific capacity and poor electrical conductivity yet need to be satisfactorily solved before the practical application of Li4Ti5O12 anode can be well achieved in lithium-ion batteries. Herein, a novel hierarchical structure of clew-like microparticles constructed by ultrafine Li4Ti5O12 nanowires has been successfully prepared via a facile approach. The combination effect of ultrafine nanowire unites and non-compact clew-like architecture provides the as-prepared Li4Ti5O12 with excellent electrochemical performance. A high reversible specific capacity of 184.1 mAh g−1 can be obtained at 20 mA g−1 after 400 cycles. What is more, a capacity of 177.8 and 152.2 mAh g−1 can be gained even after 2500 cycles respectively at 200 and 4000 mA g−1, exhibiting high capacity, superior rate property and outstanding cycling stability. This work may open up a broader vision into developing nanostructure Li4Ti5O12 anode materials for advanced lithium-ion batteries.

Template-free synthesis of hierarchical MoO2 multi-shell architectures with improved lithium storage capability

A hierarchical multi-shell structure of MoO2 is synthesized through a template-free one-pot solvothermal method. The relative MoO2 electrode exhibits high reversible specific capacity of 780mAhg−1 after 40cycles, good stability, high capacity retention and improved rate performance in the lithium ion battery application. This material has a unique hierarchical architecture which is a combination of pure hollow structure and core-shell structure. Such a hierarchical multi-shell structure can not only amplify active mass-electrolyte contact area and minimizes lithium ion diffusion path, but also provides a unique interstitial void space to relieve the huge volume change of material. Materials with a hierarchical multi-shell structure are expected to be promising candidates in lithium ion batteries application.