Nanosize Sn Particles Research Articles

Low-cost and highly safe solid-phase sodium ion battery with a Sn–C nanocomposite anode

• Nanosized Sn particles are embedded in an amorphous carbon host derived from sucrose. • Na 3 Zr 2 Si 2 PO 12 ceramic-based hybrid solid electrolyte is prepared for sodium ion battery. • Sn–C-based solid sodium battery show high discharge capacities and Coulombic efficiency. With the use of a conducting ceramic-based solid-phase hybrid electrolyte, the batteries can maintain safe and stable operation during the reversible insertion/extraction of sodium ions by the suppression of sodium dendrites. Here, Sn–C nanocomposites are prepared by a simple one-pot synthesis process, and they have a unique structure in which nanosized Sn particles are embedded in an amorphous carbon host derived from sucrose. The Sn–C nanocomposite is used to fabricate a solid-phase sodium-ion battery with a Na 3 Zr 2 Si 2 PO 12 ceramic-based hybrid solid electrolyte. The Sn–C-based solid-phase sodium battery shows high electrochemical performance with a high discharge capacity of 669.9 mA h g −1 at 0.2 C with a Coulombic efficiency close to 100%. The electrochemical alloy mechanism of the Sn–C nanocomposite is investigated by X-ray photoelectron spectroscopy. The good electrochemical performance demonstrates the advantages of using the Na 3 Zr 2 Si 2 PO 12 ceramic-based hybrid solid electrolyte and Sn–C nanocomposite in solid-phase sodium ion batteries.

Li2CO3 induced stable SEI formation: An efficient strategy to boost reversibility and cyclability of Li storage in SnO2 anodes

The unstable interfaces between a SnO2 anode and an electrolyte in a Li-ion battery dramatically impair the reversibility and cycling stability of lithiation and delithiation, resulting in low roundtrip Coulombic efficiency (CE) and fast capacity decay of SnO2-based anode materials. Herein, a simple strategy of modifying the solid electrolyte interphase (SEI) is developed to enhance the interfacial stability and lithium storage reversibility of SnO2 by compositing it with graphite (G) and an inorganic component of the SEI, such as Li2CO3 or LiF, which results in the SnO2-Li2CO3/G and SnO2-LiF/G composite anodes with high CEs, large capacities and long cycle lives. Specifically, the SnO2-Li2CO3/G composite anode exhibits an average initial CE of 79.6%, a stable reversible capacity of 927.5 mA h g−1 at a current rate of 0.2 A g−1, and a charge capacity over 1200 mA h g−1 with a CE >99% after 900 cycles at a higher current rate of 1 A g−1. It is revealed that Li2CO3 induces the formation of a dense and stable SEI on SnO2 grains and inhibits the coarsening of nanosized Sn particles generated from the dealloying reaction in the SnO2-Li2CO3/G electrode. Moreover, the CE and cycling stability of other alloying type (Si) and conversion reaction (MnO2 and Fe3O4) anodes can also be greatly promoted by simply milling with Li2CO3. Thus, a universal and simple strategy is developed to achieve highly reversible and stable electrodes for large capacity lithium storage.

Superior Cycling and Rate Performance of Micron‐Sized Tin Using Aqueous‐Based Binder as a Sustainable Anode for Lithium‐Ion Batteries

Recent developments in Sn‐based anodes for lithium‐ion batteries (LIBs) mostly rely on nanosized Sn particles with a conventional nonaqueous polyvinylidene fluoride binder, which is a major obstacle for the commercialization of Sn anodes due to the additional processing steps involved. Herein, the micron‐sized Sn (10 μm) is demonstrated as an anode material for LIBs using carbonyl‐β‐cyclodextrin as an environmentally benign and low cost aqueous binder. The optimized Sn electrode exhibits a remarkable reversible capacity of 577 mAh g−1 at 0.1 C rate between 3 and 0.05 V. A capacity of 256 and 117 mAh g−1 is obtained at 1 and 5 C, respectively, with a capacity retention of >80% after 1500 cycles. At 0.3 C lithiation rate, a delithiation capacity of 340 mAh g−1 is obtained at 5 C. The reversible capacities and cyclic stability further improve when the lithiation voltage is decreased to 0.025 V. The capacities at 0.1, 1, and 5 C are 723, 506, and 315 mAh g−1, respectively. A delithiation capacity of 478 mAh g−1 is obtained at 5 C at 0.3 C lithiation rate. It is believed that this method paves the way for using micron‐sized Sn as a sustainable anode material for LIBs.

Ultrasmall Sn Nanodots Dispersed in Cross-Linked N-Doped Carbon Cages for High-Performance Lithium Storage

Sn based materials are the promising anodes in Li-ion batteries for the advantages of high theoretical capacity (994 mAh g-1 for LIBs), high conductivity and low cost. However, the drastic volume change during charging and discharging process results in poor cycling stability. Dispersing nano-sized Sn particles in carbon matrix is an effective way to mitigate the volume change, but the thick carbon matrix may retard ion diffusion. Consider this, we designed nano-Sn/N-doped carbon microcages composites (Sn/NMCs) with Sn nanodots uniformly dispersed inside the N-doped carbon microcages through a simple spray drying process, followed by thermal treatment. The interconnected N-doped carbon skeleton enhances the electronic conductivity, meanwhile the internal channels supply fast paths for Li+ transmission. Taking the advantages of ultrasmall Sn and soft carbon matrix, the Sn/NMCs exhibit excellent electrochemical performance as Li-ion battery anode. It delivers an initial charging capacity of 780 mAh g-1 at 200 mA g-1, and maintains 472 mAh g-1 after 500 cycle.; 323 mAh g-1 is still maintained even at a high current density of 10 A g-1. Moreover, this Sn/NMCs is accessible to scale up and the modification strategy can be extended to other electrode materials. Figure 1 TEM image of Sn/NMCs and the schematic diagram of Li+ and electron transportation processes in Sn/NMCs Acknowledgments This work is supported by the National Natural Science Foundation of China (Grant No. 51371186), the “Strategic Priority Research Program” of the Chinese Project Academy of Science (Grant No.XDA09010201), Ningbo 3315 International Team of Advanced Energy Storage Materials, Zhejiang Province Key Science and Technology Innovation Team (2013TD16). Figure 1

A hierarchical tin/carbon composite as an anode for lithium-ion batteries with a long cycle life.

Tin is a promising anode candidate for next-generation lithium-ion batteries with a high energy density, but suffers from the huge volume change (ca. 260 %) upon lithiation. To address this issue, here we report a new hierarchical tin/carbon composite in which some of the nanosized Sn particles are anchored on the tips of carbon nanotubes (CNTs) that are rooted on the exterior surfaces of micro-sized hollow carbon cubes while other Sn nanoparticles are encapsulated in hollow carbon cubes. Such a hierarchical structure possesses a robust framework with rich voids, which allows Sn to alleviate its mechanical strain without forming cracks and pulverization upon lithiation/de-lithiation. As a result, the Sn/C composite exhibits an excellent cyclic performance, namely, retaining a capacity of 537 mAh g(-1) for around 1000 cycles without obvious decay at a high current density of 3000 mA g(-1) .

Electrochemical Degradation Mechanism of Nano-Sized Sn-C Composite Negative Electrodes for Libs

Lithium-ion batteries (LIBs) are an important power source for both portable devices and electric vehicles. In order for electrical vehicles with LIBs to be embraced more fully, the specific energy of LIBs needs to be improved without sacrificing safety, material availability, and cost. Tin (Sn), as a negative electrode material with various morphologies or nanostructures, is one possible solution because tin not only provides high specific energy (994 mAhg-1) compared to graphite (~374 mAh g-1), but is also inexpensive and abundant [1]. Moreover, tin can be used for the negative electrode of a sodium ion battery, which have recently received much attention as an alternative of LiBs due to much lower cost due to the natural abundance of Na [2]. In spite of the aforementioned advantages of tin as negative electrode materials, tin based electrodes are still difficult to commercialize due to their severe capacity fading during battery cycling. The fade has been associated with the large volume expansion during lithiation, but the mechanism is not yet fully understood. In order to use tin materials in practical devices, the first step is to elucidate the cause of the degradation behavior, and next is to improve the cyclability of tin based electrodes through design of material, coating, and electrolyte additive, etc. Herein, we investigated the degradation behavior of the Sn-C composite negative electrodes, using electrochemical and micro-structural methods.The Sn material used in this study was synthesized by a chemical reducing method [3]. The Sn is spherical-shaped with diameter of 80 ~120 nm, as shown in Fig. a. To fabricate negative electrodes using the prepared nano-sized Sn particles, carbon black as conducting agent and PVdF binder were added and mixed well together in NMP solvent. The ink was applied to a copper foil, dried in a vacuum oven, and calendered. Fig. b shows the XRD pattern of the prepared Sn-C electrode, where Sn peak was mainly detected. Fig.c-d shows the lithiation and delithiation curves and capacity fade of the half cell employing the Sn-C negative electrode. The cell was lithiated and delithiated at 40 mAg-1 (20 mAg-1 for the 1st cycle) between 0.01 and 1.5 VLi/Li+. As shown in Fig. c, the first irreversible capacity loss (ICL) is large (~60%) presumably due to formation of a thick SEI layer, thus reducing the cyclable Li ions and active material during the 1st lithiation. During subsequent cycles (Fig.d), the capacity decreased gradually by about 1.2 % cycle-1 from 2nd to 50thcycles probably due to loss of conductivity and active materials. To reveal more clearly this degradation behavior, we analyze the initial cycle and subsequent cycles separately. Specific methods used in each cycle include: differential capacity (dC/dV) curve, electrochemical impedance spectroscopy (EIS), Focus Ion Beam (FIB)-Scanning Electron Microscopy (SEM), X-ray diffraction (XRD), and X-ray Photoelectron Spectroscopy (XPS).

Enhanced electrochemical performance of graphene nanosheet thin film anode decorated with tin nanoparticles

Graphene nanosheet (GNS) was synthesized by using microwave plasma enhanced CVD on copper substrate and followed by evaporation of tin metal. Scanning and transmission electron microscopy show that nanosize Sn particles are well embedded into the GNS matrix. The composition, structure, and electrochemical properties were characterized by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), cyclic voltammetry (CV) and chrono-potentiometry. The first discharge capacity of as-deposited and annealed SnGNS obtained was 1551 mA h/g and 975 mA h/g, respectively. The anodes show excellent cyclic performance and coulombic efficiency.

High-performance Sn@carbon nanocomposite anode for lithium-ion batteries: Lithium storage processes characterization and low-temperature behavior

The electrochemical behavior of a composite anode for Li-ion batteries, based on nanosize tin particles embedded in electrically conducting porous multichannel carbon microtubes (Sn–PMCMT), synthesized by co-electrospinning, is here evaluated.An activation protocol aimed at maximizing anode mechanical stability and capacity retention upon cycling is presented. The results are compared with those obtained with an anode using pristine PMCMT carbon as active material.The Li uptake and release processes by Sn and C are evaluated by galvanostatic charge/discharge cycles, in order to differentiate the two contributions to the overall anode capacity. Electrochemical impedance spectroscopy (EIS) analysis is utilized in order to evaluate possible improvements to charge-transfer kinetics due to the nanosize Sn particles dispersion. Finally, the performances of the composite Sn–PMCMT anode are characterized at different charge/discharge currents and temperatures.The anode can deliver a capacity of 500mAhg−1 for more than 300 cycles, most of them at 1C or higher charge/discharge rate, which confirms its very high, stable cycling performances. Moreover, this tailored nanostructured anode retains a relevant amount of capacity even in very demanding cycling conditions, as the case for very low temperatures. These results make the proposed Sn–PMCMT an ideal candidate anode for high-performance Li-ion batteries able to operate in a wide array of operating conditions.

Characterization of sodium ion electrochemical reaction with tin anodes: Experiment and theory

Tin anodes show a rich structure and reaction chemistry which we have investigated in detail. Upon discharge five plateaus are observed corresponding to β-Sn, an unidentified phase (Na/Sn = 0.6), an amorphous phase (Na/Sn = 1.2), a hexagonal R-3m Na5Sn2, and fully sodiated I-43d Na15Sn4. With charging there are six plateaus related to the formation of Na5Sn2 followed by the formation of amorphous phases and β-Sn. Upon cycling the formation of metastable Na5Sn2 seems to be suppressed.Theoretical voltages calculated from existing crystal structures using DFT provide a good match with constant current and quasi-equilibrium measurements (GITT). Search for additional (meta)stable phases using cluster-expansion method predicts many phases lower in energy than the convex hull obtained from known structures, including the R-3m Na5Sn2 phase. The presence of multiple phases in varying lattices with similar formation energy suggests why the reaction mechanism is non-reversible. 119Sn Mössbauer spectroscopy results indicate a decrease of the isomer shift with increasing Na/Sn content, which is less pronounced than for Li–Sn compounds likely due to the lower electropositivity of Na.The electrode surface is terminated with an SEI layer rich in carbonates (Na2CO3 and Na CO3R) as evidenced by XPS. After charge at 2 V, strong evidence for the formation of oxidized Sn4+ is obtained. Subjecting the electrode to a rest after charge at 2 V reveals that aging in the electrolyte reduces the oxidized Sn4+ into Sn2+ and Sn0, and concomitantly suppresses the electrolyte decomposition represented by an anomalous discharge plateau at 1.2 V. Thereby, the catalytic decomposition of the electrolyte during discharge is caused by nanosized Sn particles covered by oxidized Sn4+ and not by pure metallic Sn.

The Sn Nano-Particles Coated on MCMB as Anodes Material for Lithium Ion Battery

Sn nano particle coatings on MCMB powder, as anodes of lithium ion battery are carried out in SnSO4 solutions by using cathodic electrochemical synthesis and subsequently dried at 100°C. The electro-deposition reaction was follow: Sn2+ + H2O ↔ SnOH+aq + H+; SnOH+aq ↔ SnOH+aqs + e-; SnOH+ads + e- → SnOH; SnOH + H+ + e- → Sn + H2O. The Sn-coated MCMB specimens are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), cyclic voltammetry (CV), and charge/discharge tests. The nano-sized Sn particles coated on MCMB powder are obtained in 0.2M SnSO4 solutions and desoition current 0.5A. An important parameter in electrode preparation is the adhesion of the coating to the current collector, which greatly affects the cyclability of the electrode. Therefore, the relationship between adhesion strength and cycle performance was investigate in this study. Charge/discharge cycle tests elucidated that Sn-coated MCMB showed higher capacity than MCMB. Compared with MCMB, the second discharge capacity of Sn–coated MCMB increased about 28.8%. After 50 cycles, the reversible capacity was about 339.6 mAhg-1. The capacity retention ratio C25/C2 was about 80.87%. It was shown good cycle life due to the nano-particles effects retarded to Sn aggregation.

High-performance Sn@carbon nanocomposite anode for lithium batteries

Nanosize tin particles (Sn-PMCMT) embedded in electrically conducting porous multichannel carbon microtubes are synthesized by co-electrospinning followed by air stabilization and carbonization in Ar/H2 atmosphere. Scanning and transmission electron microscopy show that the material is nanostructured with nanosize Sn particles well embedded into the carbon host matrix.Composite electrodes prepared using Sn-PMCMT, Super-P carbon and Na-carboxymethylcellulose as binder, exhibit a superior rate capability and exceptional cycle life in cell tests at room temperature. Discharge capacities as high as 632 mAh g−1 at 0.7 C rate are obtained during the first galvanostatic cycles. The delivered capacities are still in excess of 350 mAh g−1 after 600 cycles, most of them performed at 2 C rate. These outstanding results represent the highest performance so far reported for this type of electrode.

Wire Explosion Synthesis of a Sn/C Nanocomposite as an Anode Material for Li Secondary Batteries

As a top-down approach for nanomaterial synthesis, a “wire explosion in liquid media” process was applied to the preparation of a Sn/C nanocomposite as an alternative anode material for lithium secondary batteries. Using a highly-dispersed Sn nanoparticle suspension produced by electrical explosion of Sn wires in ethanol followed by gravimetric sedimentation for size separation and by addition of a carbon precursor and pyrolysis, we prepared nano-sized Sn particles embedded in a carbon matrix. The physical properties of the nano-sized Sn and its carbon composite were characterized by using scanning electron microscopy, transmission electron microscopy, X-ray diraction and dierential scanning calorimetry. The electrochemical property was analyzed by using cycled charge/discharge tests. The resulting Li storage performance of the Sn/C nanocomposite showed an initial discharge capacity of over 400 mAhg 1 and improved capacity retention of 340 mAhg 1 after 40 cycles. The simplicity and the scalability of nanocomposite synthesis provided by the “wire explosion in a liquid medium” process make this method a promising tool not only for new nanomaterial investigations but also for commercial production of nanomaterials.

Electrolytic Sn/Li 2O coatings for thin-film lithium ion battery anodes

Sn/Li 2O composite coatings on stainless steel substrate, as anodes of thin-film lithium battery are carried out in SnCl 2 and LiNO 3 mixed solutions by using cathodic electrochemical synthesis and subsequently annealed at 200 °C. Through cathodic polarization tests, three major regions are verified: (I) O 2 + 4H + + 4e − → 2H 2O (∼0.25 to −0.5 V), (II) 2H + + 2e − → H 2, Sn 2+ + 2e − → Sn, and NO 3 − + H 2O + 2e − → NO 2 − + 2OH − (−0.5 to −1.34 V), and (III) 2H 2O + 2e − → H 2 + 2OH − (−1.34 to −2 V vs. Ag/AgCl). The coated specimens are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV), and charge/discharge tests. The nano-sized Sn particles embedded in Li 2O matrix are obtained at the lower part of region II such as −1.2 V, while the micro-sized Sn with little Li 2O at the upper part, such as −0.7 V. Charge/discharge cycle tests elucidated that Sn/Li 2O composite film showed better cycle performance than Sn or SnO 2 film, due to the retarding effects of amorphous Li 2O on the further aggregation of Sn particles. On the other hand, the one tested for cut-off voltage at 0.9 V (vs. Li/Li +) is better than those at 1.2 and 1.5 V since the incomplete de-alloy at lower cut-off voltage may inhibit the coarsening of Sn particles, revealing capacity 587 mAh g −1 after 50 cycle, and capacity retention ratio C50/C2 81.6%, higher than 63.5% and 49.1% at 1.2 and 1.5 V (vs. Li/Li +), respectively.

Sn/graphene nanocomposite with 3D architecture for enhanced reversible lithium storage in lithium ion batteries

A general strategy has been demonstrated to achieve optimum electrochemical performance by constructing 3D nanocomposite architecture with the combination of nanosize Sn particles and graphene nanosheets. In the first step, the lithium storage properties of graphene have been investigated by first principles calculations. The results show that lithium can be stably stored on both sides of graphene sheets (LiC3), inducing in a theoretical capacity of 744 mAh/g. In the second step, a synthetic approach has been designed to prepare Sn/graphene nanocomposite with 3D architecture, in which Sn nanoparticles act as a spacer to effectively separate graphene nanosheets. FESEM and TEM analysis revealed the homogeneous distribution of Sn nanoparticles (2–5 nm) in graphene nanosheet matrix. Cyclic voltammetry measurement has proved the highly reversible nature of the reaction between Li+ and Sn/graphene nanocomposite. The 3D nanoarchitecture gives the Sn/graphene nanocomposite electrode an enhanced electrochemical performance. This strategy can be extended to prepare other anode and cathode materials for advanced energy storage and conversion devices such as lithium ion batteries, supercapacitors, and fuel cells.

Ni-P Coated Sn Powders as Anode for Lithium Secondary Batteries

Nano-sized Sn particles were coated with Ni-P layer using an electroless deposition method and their anodic performance was tested for lithium secondary batteries. Uniform coating layers were obtained, of which the thickness was controlled by varying the <TEX>$Ni^{2+}$</TEX> concentration in the plating bath. It was found that the Ni-P layer plays two important roles in improving the anodic performance of Sn powder electrode. First, it prevents the inter-particle aggregation between Sn particles during the charge/discharge process. Second, it provides an electrical conduction pathway to the Sn particles, which allows an electrode fabrication without an addition of conductive carbon. A pseudo-optimized sample showed a good cyclability and high capacity (<TEX>$>400mAh\;g^{-1}$</TEX>) even without conductive carbon loading.

Electrochemical characteristics of tin-coated MCMB graphite as anode in Lithium-ion cells

Several Sn-coated MCMB (mesocarbon microbeads) graphite anode materials were prepared by microencapsulating nanosize Sn particles in MCMB. The nanosized tin particles are homogeneously dispersed in MCMB graphite matrix via electroless in situ chemical reduction. X-ray diffraction and EDS measurement confirms the presence of Sn in MCMB matrix. A systematic electrochemical testing has been performed on the Sn-coated MCMB graphite electrodes. The tin-coated MCMB graphite electrodes demonstrated an improvement in lithium storage capacity. The reaction process of lithium intercalation and de-intercalation in MCMB structure and lithium alloying with tin has been identified by cyclic voltammetry measurement. The micro-encapsulation of Sn in MCMB graphite can enhance the electrochemical properties of MCMB graphite anodes.

Electrochemical properties of nanosize Sn-coated graphite anodes in lithium-ion cells

A series of Sn-coated graphite composite materials for lithium-ion batteries were prepared by microencapsulating nanosize Sn particles in graphite. The nanosize Sn particles are homogeneously dispersed in the graphite matrix via electroless chemical reduction. The tin-graphite composite showed a great improvement in lithium storage capacity. Since Sn is an active element to lithium, Sn can react with lithium to form Li4.4Sn alloys, a reaction accompanied by a dramatic volume increase, whereas the ductile graphite matrix provides a perfect buffer layer to absorb this volume expansion. Therefore, the integrity of the composite electrode is preserved during lithium insertion and extraction. Cyclic voltammetry was employed to identify the reaction process involved in lithium insertion and extraction in the graphite structure, as well as lithium alloying with tin. The tin-graphite composites provide a new type of anode material for lithium-ion batteries with an increased capacity.

Synthesis of tin-encapsulated spherical hollow carbon for anode material in lithium secondary batteries.

The tributylphenyltin (TBPT)-encapsulated resorcinol (R)-formaldehyde (F) sol was prepared inside the micelles of cetyltrimethylammonium bromide (CTAB). This core-shell-type sol was polymerized and further carbonized to obtain nanosized Sn-encapsulated spherical hollow carbon. The size of spherical hollow carbon and Sn metal particles was controllable by changing the R/CTAB or TBPT/CTAB mole ratio, respectively. It is likely that, when tested as the anode in Li secondary batteries, the spherical hollow carbon acts as a barrier to prevent the aggregation of nanosized Sn particles and provides a void space for Sn metal particles to experience a volume change without a collapse of carbon shell, giving rise to a better cycle performance than that of pure Sn metal.

Melting of nanostructured Sn probed by in-situ x-ray diffraction

In-situ x-ray diffraction allowed us to track the melting process of nanosized Sn droplets obtained by Sn evaporation on a substrate heated above the Sn melting temperature. We provide further evidence that the melting temperature of nanosized Sn particles is dramatically decreased with respect to the bulk value. The results, obtained by the analysis of in-situ x-ray diffraction patterns, indicate that thermal expansion of lattice parameters is anisotropic, the differences being related to the tetragonal crystal structure of β-Sn. Moreover, the behavior of Sn–Sn distance against the temperature suggests that the melting temperature is related to a critical Sn–Sn distance.