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

Soft-in-Rigid Strategy Promoting Rapid and High-Capacity Lithium Storage by Chemical Scissoring

Large and rapid lithium storage is hugely demanded for high-energy/power lithium-ion batteries; however, it is difficult to achieve these two indicators simultaneously. Sn-based materials with a (de)alloying mechanism show low working potential and high theoretical capacity, but the huge volume expansion and particle agglomeration of Sn restrict cyclic stability and rate capability. Herein, a soft-in-rigid concept was proposed and achieved by chemical scissoring where a soft Sn-S bond was chosen as chemical tailor to break the Ti-S bond to obtain a loose stacking structure of 1D chain-like Sn1.2Ti0.8S3. The in situ and ex situ (micro)structural characterizations demonstrate that the Sn-S bonds are reduced into Sn domains and such Sn disperses in the rigid Ti-S framework, thus relieving the volume expansion and particle agglomeration by chemical and physical shielding. Benefiting from the merits of large-capacity Sn with an alloying mechanism and high-rate TiS2 with an intercalation mechanism, the Sn1.2Ti0.8S3 anode offers a high specific capacity of 963.2 mA h g-1 at 0.1 A g-1 after 100 cycles and a reversible capacity of 250 mA h g-1 at 10 A g-1 after 3900 cycles. Such a strategy realized by chemical tailoring at the structural unit level would broaden the prospects for constructing joint high-capacity and high-rate LIB anodes.

High Coulomb Efficiency Sn-Co Alloy/rGO Composite Anode Material for Li-ion Battery with Long Cycle-Life

The low cycle performance and low Coulomb efficiency of tin-based materials confine their large-scale commercial application for lithium-ion batteries. To overcome the shortage of volume expansion of pristine tin, Sn-Co alloy/rGO composites have been successfully synthesized by chemical reduction and sintering methods. The effects of sintering temperature on the composition, structure and electrochemical properties of Sn-Co alloy/rGO composites were investigated by experimental study and first-principles calculation. The results show that Sn-Co alloys are composed of a large number of CoSn and trace CoSn₂ intermetallics, which are uniformly anchored on graphene nanosheets. The sintering treatment effectively improves the electrochemical performance, especially for the first Coulomb efficiency. The first charge capacity of Sn-Co alloy/rGO composites sintered at 450 °C is 675 mAh·g^-1, and the corresponding Coulomb efficiency reaches 80.4%. This strategy provides a convenient approach to synthesizing tin-based materials for high-performance lithium-ion batteries.

Amorphous SnSx (1 < x < 2) Anode with a High-Rate Li Alloying Reaction for Li-Ion Batteries

Here, we report the conversion of bulk Li alloying anode reactions into surface reactions by the construction of amorphous structured SnS_x active materials encapsulated in robust carbon nanofiber anodes. The high-temperature phase transformation from SnS to SnS₂ is used to construct the SnS_x (1 < x < 2) active material with an amorphous structure and ultra-tiny particle size, leading to a decreased Li⁺ diffusion path, weakened volume change ratio, but considerably enhanced capacitance. The amorphous structure changes the Li-storage mechanism from Li-intercalation to the surface reaction, which endows each active particle with a rapid (de)lithiation characteristic. As a result, the high-rate (dis)charge property with a long-term cycle life is obtained for SnS_x@NC, which delivers an excellent rate capability of 633.4 mAh g^-1 under 7 A g^-1 and a capability retention of 785.2 mAh g^-1 after 1600 cycles under 2 A g^-1.

A Review on Mechanochemistry: Approaching Advanced Energy Materials with Greener Force

Mechanochemistry with solvent-free and environmentally friendly characteristics is one of the most promising alternatives to traditional liquid-phase-based reactions, demonstrating epoch-making significance in the realization of different types of chemistry. Mechanochemistry utilizes mechanical energy to promote physical and chemical transformations to design complex molecules and nanostructured materials, encourage dispersion and recombination of multiphase components, and accelerate reaction rates and efficiencies via highly reactive surfaces. In particular, mechanochemistry deserves special attention because it is capable of endowing energy materials with unique characteristics and properties. Herein, the latest advances and progress in mechanochemistry for the preparation and modification of energy materials are reviewed. An outline of the basic knowledge, methods, and characteristics of different mechanochemical strategies is presented, distinguishing this review from most mechanochemistry reviews that only focus on ball-milling. Next, this outline is followed by a detailed and insightful discussion of mechanochemistry-involved energy conversion and storage applications. The discussion comprehensively covers aspects of energy transformations from mechanical/optical/chemical energy to electrical energy. Finally, next-generation advanced energy materials are proposed. This review is intended to bring mechanochemistry to the frontline and guide this burgeoning field of interdisciplinary research for developing advanced energy materials with greener mechanical force.

Improving Na/Na3 Zr2 Si2 PO12 Interface via SnOx /Sn Film for High-Performance Solid-State Sodium Metal Batteries

Sodium (Na) metal batteries have attracted much attention due to their rich resources, low cost, and high energy density. As a promising solid electrolyte, Na₃ Zr₂ Si₂ PO₁₂ (NZSP) is expected to be used in solid-state Na metal batteries addressing the safety concerns. However, due to the poor contact between NZSP and the Na metal, the interfacial resistance is too large to gain proper performance for practical solid-state batteries (SSBs) application. Here, a SnO_x /Sn film is successfully introduced to improve the interface between Na and NZSP for enhancing the electrochemical performance of SSBs. As a result, the Na/NZSP interfacial resistance is dramatically reduced from 581 to 3 Ω cm² . The modified Na||Na symmetric cell keeps cycling over 1500 h with an overpotential of 40 mV at 0.1 mA cm^-2 at room temperature. Even at current densities of 0.3 and 0.5 mA cm^-2 , the cell still maintains an excellent cyclability. When coupled with NaTi₂ (PO₄ )₃ and a Na₃ V₂ (PO₄ )₃ cathode, the full-cell demonstrates a good performance at 0.2 C and 1 C, respectively. The present work provides an effective way to solve the interface issue of SSBs.

Intercalation and delamination of Ti2SnC with high lithium ion storage capacity

Li-ion batteries attract great attention due to the rapidly increasing and urgent demand for high energy storage devices. MAX phase compounds, layered ternary transition metal carbides and/or nitrides show promise as candidate materials of electrodes for Li-ion batteries. However, the highest specific capacity reported up to now is relatively low (180 mA h g^-1), preventing them from use in real applications. Exploring more MAX phase compounds with delaminated two-dimensional structure is an effective solution to increase the specific capacity. Herein, we report the reversible electrochemical intercalation of Li⁺ into Ti₂SnC (MAX phase) nanosheets. Owing to the synergistic effects of intercalation and dimethyl sulfoxide (DMSO)-assisted exfoliation, Ti₂SnC nanosheets are successfully obtained via sonication in DMSO. Moreover, when using as an anode of a Li-ion battery, Ti₂SnC nanosheets exhibited an increasing specific capacity with cycling due to the exfoliation of Ti₂SnC nanosheets via reversible Li-ion intercalation. After 1000 charge-discharge cycles, Ti₂SnC nanosheets delivered a high specific capacity of 735 mA h g^-1 at a current density of 50 mA g^-1, which is far better than other MAX phases, such as Ti₂SC, Ti₃SiC₂ and Nb₂SnC. The current work demonstrates the Li-ion storage potential and indicates a novel strategy for further intercalation and delamination of MAX phases.

Enhanced Electrochemical Performance Promoted by Tin in Silica Anode Materials for Stable and High-Capacity Lithium-Ion Batteries

Although the silicon oxide (SiO2) as an anode material shows potential and promise for lithium-ion batteries (LIBs), owing to its high capacity, low cost, abundance, and safety, severe capacity decay and sluggish charge transfer during the discharge-charge process has caused a serious challenge for available applications. Herein, a novel 3D porous silicon oxide@Pourous Carbon@Tin (SiO2@Pc@Sn) composite anode material was firstly designed and synthesized by freeze-drying and thermal-melting self-assembly, in which SiO2 microparticles were encapsulated in the porous carbon as well as Sn nanoballs being uniformly dispersed in the SiO2@Pc-like sesame seeds, effectively constructing a robust and conductive 3D porous Jujube cake-like architecture that is beneficial for fast ion transfer and high structural stability. Such a SiO2@Pc@Sn micro-nano hierarchical structure as a LIBs anode exhibits a large reversible specific capacity ~520 mAh·g-1, initial coulombic efficiency (ICE) ~52%, outstanding rate capability, and excellent cycling stability over 100 cycles. Furthermore, the phase evolution and underlying electrochemical mechanism during the charge-discharge process were further uncovered by cyclic voltammetry (CV) investigation.

Sandwich shelled TiO2@Co3O4@Co3O4/C hollow spheres as anode materials for lithium ion batteries

A sandwich shelled hollow TiO₂@Co₃O₄@Co₃O₄/C composite is synthesized by consecutive coating of Co₃O₄ nanosheets and TiO₂ particles on Co₃O₄/C hollow spheres. The composite delivers an excellent lithium storage performance, maintaining 1081.78 mA h g^-1 after 100 cycles at 0.2 A g^-1 and 772.23 mA h g^-1 after 300 cycles at 1 A g^-1, due to its superior structure combining the advantages of each component with favorable electron-transfer, Li⁺-diffusion properties, and distinguished stability.

Organic molecule confinement reaction for preparation of the Sn nanoparticles@graphene anode materials in Lithium-ion battery

Sn@Graphene composites as anode materials in Lithium-ion batteries have attracted intensive interest due to the inherent high capacity. On the other side, the high atomic ratio (Li_4.4Sn) induces the pulverization of the electrode with cycling. Thus, suppressing pulverization by designing the structure of the materials is an essential key for improving cyclability. Applying the nanotechnologies such as electrospinning, soft/hard nano template strategy, surface modification, multi-step chemical vapor deposition (CVD), and so on has demonstrated the huge advantage on this aspect. These strategies are generally used for homogeneous dispersing Sn nanomaterials in graphene matrix or constructing the voids in the inner of the materials to obtain the mechanical buffer effect. Unfortunately, these processes induce huge energy consumption and complicated operation. To solve the issue, new nanotechnology for the composites by the bottom-up strategy (Organic Molecule Confinement Reaction (OMCR)) was shown in this report. A 3D organic nanoframes was synthesized as a graphene precursor by low energy nano emulsification and photopolymerization. SnO₂ nanoparticles@3D organic nanoframes as the composites precursor were in-situ formed in the hydrothermal reaction. After the redox process by the calcination, the Sn nanoparticles with nanovoids (~100 nm, uniform size) were homogeneously dispersed in a Two-Dimensional Laminar Matrix of graphene nanosheets (2DLM_G) by the in-situ patterning and confinement effect from the 3D organic nanoframes. The pulverization and crack of the composites were effectively suppressed, which was proved by the electrochemical testing. The Sn nanoparticles@2DLM_G not delivered just the high cyclability during 200 cycles, but also firstly achieved a high specific capacity (539 mAh g^-1) at the low loading Sn (19.58 wt%).

Stabilization of Sn Anode through Structural Reconstruction of a Cu-Sn Intermetallic Coating Layer

The metallic tin (Sn) anode is a promising candidate for next-generation lithium-ion batteries (LIBs) due to its high theoretical capacity and electrical conductivity. However, Sn suffers from severe mechanical degradation caused by large volume changes during lithiation/delithiation, which leads to a rapid capacity decay for LIBs application. Herein, a Cu-Sn (e.g., Cu₃ Sn) intermetallic coating layer (ICL) is rationally designed to stabilize Sn through a structural reconstruction mechanism. The low activity of the Cu-Sn ICL against lithiation/delithiation enables the gradual separation of the metallic Cu phase from the Cu-Sn ICL, which provides a regulatable and appropriate distribution of Cu to buffer volume change of Sn anode. Concurrently, the homogeneous distribution of the separated Sn together with Cu promotes uniform lithiation/delithiation, mitigating the internal stress. In addition, the residual rigid Cu-Sn intermetallic shows terrific mechanical integrity that resists the plastic deformation during the lithiation/delithiation. As a result, the Sn anode enhanced by the Cu-Sn ICL shows a significant improvement in cycling stability with a dramatically reduced capacity decay rate of 0.03% per cycle for 1000 cycles. The structural reconstruction mechanism in this work shines a light on new materials and structural design that can stabilize high-performance and high-volume-change electrodes for rechargeable batteries and beyond.

Intercalating Sn/Fe Nanoparticles in Compact Carbon Monolith for Enhanced Lithium Ion Storage

Given its high-capacity of multielectron (de-)lithiation, SnO2 is deemed as a competitive anode substance to tackle energy density restrictions of low-theoretical-capacity traditional graphite. However, its pragmatic adhibition seriously encounters poor initial coulombic efficiency from irreversible Li2O formation and drastic volume change during repeated charge/discharge. Here, an applicable gel pyrolysis methodology establishes a SnO2/Fe2O3 intercalated carbon monolith as superior anode materials for Li ion batteries to effectively surmount problems of SnO2. Its bulk-like, micron-sized, compact, and non-porous structures with low area surfaces (14.2 m2 g−1) obviously increase the tap density without compromising the transport kinetics, distinct from myriad hierarchically holey metal/carbon materials recorded till date. During the long-term Li+ insertion/extraction, the carbon matrix not only functions as a stress management framework to alleviate the stress intensification on surface layers, enabling the electrode to retain its morphological/mechanic integrity and yielding a steady solid electrolyte interphase film, but also imparts very robust connection to stop SnO2 from coarsening/losing electric contact, facilitating fast electrolyte infiltration and ion/electron transfer. Besides, the closely contacted and evenly distributed Fe2O3/SnO2 nanoparticles supply additional charge-transfer driving force, thanks to a built-in electric field. Benefiting from such virtues, the embedment of binary metal oxides in the dense carbons enhances initial Coulombic efficiency up to 67.3%, with an elevated reversible capacity of 726 mAh/g at 0.2 A/g, a high capacity retention of 84% after 100 cycles, a boosted rate capability between 0.2 and 3.2 A g−1, and a stable cycle life of 466 mAh/g over 200 cycles at 1 A g−1. Our scenario based upon this unique binary metal-in-carbon sandwich compact construction to achieve the stress regulation and the so-called synergistic effect between metals or metal oxides and carbons is economically effective and tractable enough to scale up the preparation and can be rifely employed to other oxide anodes for ameliorating their electrochemical properties.

Tin and Tin Compound Materials as Anodes in Lithium-Ion and Sodium-Ion Batteries: A Review

Tin and tin compounds are perceived as promising next-generation lithium (sodium)-ion batteries anodes because of their high theoretical capacity, low cost and proper working potentials. However, their practical applications are severely hampered by huge volume changes during Li⁺ (Na⁺) insertion and extraction processes, which could lead to a vast irreversible capacity loss and short cycle life. The significance of morphology design and synergic effects-through combining compatible compounds and/or metals together-on electrochemical properties are analyzed to circumvent these problems. In this review, recent progress and understanding of tin and tin compounds used in lithium (sodium)-ion batteries have been summarized and related approaches to optimize electrochemical performance are also pointed out. Superiorities and intrinsic flaws of the above-mentioned materials that can affect electrochemical performance are discussed, aiming to provide a comprehensive understanding of tin and tin compounds in lithium(sodium)-ion batteries.

Tin-graphene tubes as anodes for lithium-ion batteries with high volumetric and gravimetric energy densities

Limited by the size of microelectronics, as well as the space of electrical vehicles, there are tremendous demands for lithium-ion batteries with high volumetric energy densities. Current lithium-ion batteries, however, adopt graphite-based anodes with low tap density and gravimetric capacity, resulting in poor volumetric performance metric. Here, by encapsulating nanoparticles of metallic tin in mechanically robust graphene tubes, we show tin anodes with high volumetric and gravimetric capacities, high rate performance, and long cycling life. Pairing with a commercial cathode material LiNi_0.6Mn_0.2Co_0.2O₂, full cells exhibit a gravimetric and volumetric energy density of 590 W h Kg⁻¹ and 1,252 W h L⁻¹, respectively, the latter of which doubles that of the cell based on graphite anodes. This work provides an effective route towards lithium-ion batteries with high energy density for a broad range of applications.

Here the authors report a tin anode design by encapsulating tin nanoparticles in graphene tubes. The design exhibits high capacity, good rate performance and cycling stability. Pairing with NMC, the full cell delivers a volumetric energy density twice as high as that for the commercial cell.

Stringing Bimetallic Metal-Organic Framework-Derived Cobalt Phosphide Composite for High-Efficiency Overall Water Splitting

Water electrolysis is an emerging energy conversion technology, which is significant for efficient hydrogen (H2) production. Based on the high-activity transition metal ions and metal alloys of ultrastable bifunctional catalyst, the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) are the key to achieving the energy conversion method by overall water splitting (OWS). This study reports that the Co-based coordination polymer (ZIF-67) anchoring on an indium-organic framework (InOF-1) composite (InOF-1@ZIF-67) is treated followed by carbonization and phosphorization to successfully obtain CoP nanoparticles-embedded carbon nanotubes and nitrogen-doped carbon materials (CoP-InNC@CNT). As HER and OER electrocatalysts, it is demonstrated that CoP-InNC@CNT simultaneously exhibit high HER performance (overpotential of 153 mV in 0.5 m H2SO4 and 159 mV in 1.0 m KOH) and OER performance (overpotential of 270 mV in 1.0 m KOH) activities to reach the current density of 10 mA cm-2. In addition, these CoP-InNC@CNT rods, as a cathode and an anode, can display an excellent OWS performance with η10 = 1.58 V and better stability, which shows the satisfying electrocatalyst for the OWS compared to control materials. This method ensures the tight and uniform growth of the fast nucleating and stable materials on substrate and can be further applied for practical electrochemical reactions.

Filled Carbon Nanotubes as Anode Materials for Lithium-Ion Batteries

Downsizing well-established materials to the nanoscale is a key route to novel functionalities, in particular if different functionalities are merged in hybrid nanomaterials. Hybrid carbon-based hierarchical nanostructures are particularly promising for electrochemical energy storage since they combine benefits of nanosize effects, enhanced electrical conductivity and integrity of bulk materials. We show that endohedral multiwalled carbon nanotubes (CNT) encapsulating high-capacity (here: conversion and alloying) electrode materials have a high potential for use in anode materials for lithium-ion batteries (LIB). There are two essential characteristics of filled CNT relevant for application in electrochemical energy storage: (1) rigid hollow cavities of the CNT provide upper limits for nanoparticles in their inner cavities which are both separated from the fillings of other CNT and protected against degradation. In particular, the CNT shells resist strong volume changes of encapsulates in response to electrochemical cycling, which in conventional conversion and alloying materials hinders application in energy storage devices. (2) Carbon mantles ensure electrical contact to the active material as they are unaffected by potential cracks of the encapsulate and form a stable conductive network in the electrode compound. Our studies confirm that encapsulates are electrochemically active and can achieve full theoretical reversible capacity. The results imply that encapsulating nanostructures inside CNT can provide a route to new high-performance nanocomposite anode materials for LIB.

Monodisperse CoSn and NiSn Nanoparticles Supported on Commercial Carbon as Anode for Lithium- and Potassium-Ion Batteries

Monodisperse CoSn and NiSn nanoparticles were prepared in solution and supported on commercial carbon black. The obtained nanocomposites were applied as anodes for Li- and K-ion batteries. CoSn@C delivered stable average capacities of 850, 650, and 500 mAh g^-1 at 0.2, 1.0, and 2.0 A g^-1, respectively, well above those of commercial graphite anodes. The capacity of NiSn@C retained up to 575 mAh g^-1 at a current of 1.0 A g^-1 over 200 continuous cycles. Up to 74.5 and 69.7% pseudocapacitance contributions for Li-ion batteries were measured for CoSn@C and NiSn@C, respectively, at 1.0 mV s^-1. CoSn@C was further tested in full-cell lithium-ion batteries with a LiFePO₄ cathode to yield a stable capacity of 350 mAh g^-1 at a rate of 0.2 A g^-1. As electrode in K-ion batteries, CoSn@C composites presented a stable capacity of around 200 mAh g^-1 at 0.2 A g^-1 over 400 continuous cycles, and NiSn@C delivered a lower capacity of around 100 mAh g^-1 over 300 cycles.

Hierarchical Sulfur-Doped Graphene Foam Embedded with Sn Nanoparticles for Superior Lithium Storage in LiFSI-Based Electrolyte

Lithium-ion batteries based on tin (Sn) anode have the advantage of high energy density at a reasonable cost. However, their commercialization suffers from rapid capacity fading caused by active material aggregation, huge volumetric change, and continuous formation/deformation of solid-electrolyte interphase (SEI). Herein, we report an anode made of nanosized metallic Sn particles embedded in a hierarchically porous sulfur-doped graphene foam (Sn@3DSG). In this design, the sulfur-doped graphene foam provides abundant active defect sites to facilitate the rapid lithium-ion diffusion from outside to inside the Sn nanoparticles. Meanwhile, the hierarchical pores resulting from the self-assembly of graphene and evaporation of nanosized metallic Zn provide sufficient space to hold the volumetric changes of Sn. Owing to these merits, the as-prepared Sn electrode exhibits an excellent lithiated capacity (1272 mA h g^-1 at 200 mA g^-1) and high-rate performance (345 mA h g^-1 at 2000 mA g^-1) in the LiFSI-based electrolyte. It is also discovered that a LiF-Li₃N-rich SEI layer is formed on the surface of the Sn electrode in a LiFSI-based electrolyte, which is beneficial for enhancing the electrode's cycling stability. Our work shows great promise of composite Sn anodes for future high-energy-density lithium-ion batteries.

Facile Synthesis of Sn/Nitrogen-Doped Reduced Graphene Oxide Nanocomposites with Superb Lithium Storage Properties

Sn/Nitrogen-doped reduced graphene oxide (Sn@N-G) composites have been successfully synthesized via a facile method for lithium-ion batteries. Compared with the Sn or Sn/graphene anodes, the Sn@N-G anode exhibits a superb rate capability of 535 mAh g⁻¹ at 2C and cycling stability up to 300 cycles at 0.5C. The improved lithium-storage performance of Sn@N-G anode could be ascribed to the effective graphene wrapping, which accommodates the large volume change of Sn during the charge–discharge process, while the nitrogen doping increases the electronic conductivity of graphene, as well as provides a large number of active sites as reservoirs for Li⁺ storage.

Nanocrystal Conversion-Assisted Design of Sn-Fe Alloy with a Core-Shell Structure as High-Performance Anodes for Lithium-Ion Batteries

Sn-based alloy materials are strong candidates to replace graphitic carbon as the anode for the next generation lithium-ion batteries because of their much higher gravimetric and volumetric capacity. A series of nanosize Sn _y Fe alloys derived from the chemical transformation of preformed Sn nanoparticles as templates have been synthesized and characterized. An optimized Sn₅Fe/Sn₂Fe anode with a core-shell structure delivered 541 mAh·g^-1 after 200 cycles at the C/2 rate, retaining close to 100% of the initial capacity. Its volumetric capacity is double that of commercial graphitic carbon. It also has an excellent rate performance, delivering 94.8, 84.3, 72.1, and 58.2% of the 0.1 C capacity (679.8 mAh/g) at 0.2, 0.5, 1 and 2 C, respectively. The capacity is recovered upon lowering the rate. The exceptional cycling/rate capability and higher gravimetric/volumetric capacity make the Sn _y Fe alloy a potential candidate as the anode in lithium-ion batteries. The understanding of Sn _y Fe alloys from this work also provides insight for designing other Sn-M (M = Co, Ni, Cu, Mn, etc.) system.

Sn-encapsulated N-doped porous carbon fibers for enhancing lithium-ion battery performance

Tin (Sn) has wide prospects in applications as an anode electrode material for Li-ion batteries, due to its high theoretical specific capacity. However, the large volume expansion of Sn during the charge–discharge process causes a performance reduction of lithium-ion batteries (LIBs). Here, Sn encapsulated N-doped porous carbon fibers (Sn/NPCFs) were synthesized through an electrospinning method with a pyrolysis process. This structure was beneficial for the lithium ion/electron diffusion and buffered the large volume change. By adjusting the amount of Sn, the hybrid carbon fibers with different Sn/carbon ratios could be prepared, and the morphology, composition and properties of the Sn/NPCFs were characterized systematically. The results indicated that the Sn/NPCFs with a Sn-precursor/polymer weight ratio at 0.5 : 1 showed the best cycling stability and specific capacity, preserving the specific capacity of 400 mA h g⁻¹ at the current density of 500 mA g⁻¹ even after 100 cycles.

Sn-encapsulated N-doped porous carbon fibers showed enhanced lithium-ion battery performance due to the Sn loading and porous structure.

Tin nanoparticles embedded in an N-doped microporous carbon matrix derived from ZIF-8 as an anode for ultralong-life and ultrahigh-rate lithium-ion batteries

A carbon matrix with abundant micropores derived from ZIF-8 can confine Sn particles in an ultrasmall nanosize, contributing to the buffering of the huge volume changes.

Rattle-type porous Sn/C composite fibers with uniformly distributed nanovoids containing metallic Sn nanoparticles for high-performance anode materials in lithium-ion batteries

Rattle-type porous Sn/carbon (Sn/C) composite fibers with uniformly distributed nanovoids containing metallic Sn nanoparticles in void space surrounded by C walls (denoted as RT-Sn@C porous fiber) were prepared by electrospinning and subsequent facile heat-treatment. Highly concentrated polystyrene nanobeads used as a sacrificial template played a key role in the synthesis of the unique structured RT-Sn@C porous fiber. The RT-Sn@C porous fiber exhibited excellent long-term cycling and rate performances. The discharge capacity of the RT-Sn@C porous fiber at the 1000^th cycle was 675 mA h g^-1 at a high current density of 3.0 A g^-1. The RT-Sn@C porous fiber had final discharge capacities of 991, 924, 890, 848, 784, 717, 679, and 614 mA h g^-1 at current densities of 0.1, 0.2, 0.3, 0.5, 1.0, 2.0, 3.0, 5.0, and 10.0 A g^-1, respectively. The numerous void spaces, surrounding a Sn nanoparticle as the rattle-type particle, and the surrounding C could efficiently accommodate the volume changes of the Sn nanoparticles, improve the electrical conductivity, and enable efficient penetration of the liquid electrolyte into the structure.

Tin Nanoparticles Encapsulated Carbon Nanoboxes as High-Performance Anode for Lithium-Ion Batteries

One of the crucial challenges for applying Sn as an anode of lithium-ion batteries (LIBs) is the dramatic volume change during lithiation/delithiation process, which causes a rapid capacity fading and then deteriorated battery performance. To address this issue, herein, we report the design and fabrication of Sn encapsulated carbon nanoboxes (denoted as Sn@C) with yolk@shell architectures. In this design, the carbon shell can facilitate the good transport kinetics whereas the hollow space between Sn and carbon shell can accommodate the volume variation during repeated charge/discharge process. Accordingly, this composite electrode exhibits a high reversible capacity of 675 mAh g⁻¹ at a current density of 0.8 A g⁻¹ after 500 cycles and preserves as high as 366 mAh g⁻¹ at a higher current density of 3 A g⁻¹ even after 930 cycles. The enhanced electrochemical performance can be ascribed to the crystal size reduction of Sn cores and the formation of polymeric gel-like layer outside the electrode surface after long-term cycles, resulting in improved capacity and enhanced rate performance.

The Design and Synthesis of Hollow Micro-/Nanostructures: Present and Future Trends

Hollow micro-/nanostructures have attracted tremendous interest owing to their intriguing structure-induced physicochemical properties and great potential for widespread applications. With the development of modern synthetic methodology and analytical instruments, a rapid structural/compositional evolution of hollow structures from simple to complex has occurred in recent decades. Here, an updated overview of research progress made in the synthesis of hollow structures is provided. After an introduction of definition and classification, achievements in synthetic approaches for these delicate hollow architectures are presented in detail. According to formation mechanisms, these strategies can be categorized into four different types, including hard-templating, soft-templating, self-templated, and template-free methods. In particular, the rationales and emerging innovations in conventional templating syntheses are in focus. The development of burgeoning self-templating strategies based on controlled etching, outward diffusion, and heterogeneous contraction is also summarized. In addition, a brief overview of template-free methods and recent advances on combined mechanisms is provided. Notably, the strengths and weaknesses of each category are discussed in detail. In conclusion, a perspective on future trends in the research of hollow micro-/nanostructures is given.

Organometallic Precursor-Derived SnO2/Sn-Reduced Graphene Oxide Sandwiched Nanocomposite Anode with Superior Lithium Storage Capacity

Benefiting from the reversible conversion reaction upon delithiation, nanosized SnO₂, with its theoretical capacity of 1494 mA h g^-1, has gained special attention as a promising anode material. Here, we report a self-assembled SnO₂/Sn-reduced graphene oxide (rGO) sandwich nanocomposite developed by organometallic precursor coating and in situ transformation. Ultrafine SnO₂ nanoparticles with an average diameter of 5 nm are sandwiched within the rGO/carbonaceous network, which not only greatly alleviates the volume changes upon lithiation and aggregation of SnO₂ nanoparticles but also facilitates the charge transfer and reaction kinetics of SnO₂ upon lithiation/delithiation. As a result, the SnO₂/Sn-rGO nanocomposite exhibited a superior lithium storage capacity with a reversible capacity of 1307 mA h g^-1 at a current density of 80 mA g^-1 in the potential window of 0.01-2.5 V versus Li⁺/Li and showed a reversible capacity of 767 mA h g^-1 over 200 cycles at a current density of 400 mA g^-1. When cycling at a higher current density of 1600 mA g^-1, the SnO₂/Sn-rGO nanocomposite showed a highly stable capacity of 449 mA g^-1 without obvious decay after 400 cycles.

Self-Relaxant Superelastic Matrix Derived from C60 Incorporated Sn Nanoparticles for Ultra-High-Performance Li-Ion Batteries

Homogeneously dispersed Sn nanoparticles approximately ⩽10 nm in a polymerized C₆₀ (PC₆₀) matrix, employed as the anode of a Li-ion battery, are prepared using plasma-assisted thermal evaporation coupled by chemical vapor deposition. The self-relaxant superelastic characteristics of the PC₆₀ possess the ability to absorb the stress-strain generated by the Sn nanoparticles and can thus alleviate the problem of their extreme volume changes. Meanwhile, well-dispersed dot-like Sn nanoparticles, which are surrounded by a thin SnO₂ layer, have suitable interparticle spacing and multilayer structures for alleviating the aggregation of Sn nanoparticles during repeated cycles. The Ohmic characteristic and the built-in electric field formed in the interparticle junction play important roles in enhancing the diffusion and transport rate of Li ions. SPC-50, a Sn-PC₆₀ anode consisting of 50 wt % Sn and 50 wt % PC₆₀, as confirmed by energy-dispersive X-ray spectroscopy analysis, exhibited the highest electrochemical performance. The resulting SPC-50 anode, in a half-cell configuration, exhibited an excellent capacity retention of 97.18%, even after 5000 cycles at a current density of 1000 mA g^-1 with a discharge capacity of 834.25 mAh g^-1. In addition, the rate-capability performance of this SPC-50 half-cell exhibited a discharge capacity of 544.33 mAh g^-1 at a high current density of 10 000 mA g^-1, even after the current density was increased 100-fold. Moreover, a very high discharge capacity of 1040.09 mAh g^-1 was achieved with a capacity retention of 98.67% after 50 cycles at a current density of 100 mA g^-1. Futhermore, a SPC-50 full-cell containing the LiCoO₂ cathode exhibited a discharge capacity of 801.04 mAh g^-1 and an areal capacity of 1.57 mAh cm^-2 with a capacity retention of 95.27% after 350 cycles at a current density of 1000 mA g^-1.

Self-Healing Wide and Thin Li Metal Anodes Prepared Using Calendared Li Metal Powder for Improving Cycle Life and Rate Capability

The commercialization of Li metal electrodes is a long-standing objective in the battery community. To accomplish this goal, the formation of Li dendrites and mossy Li deposition, which cause poor cycle performance and safety issues, must be resolved. In addition, it is necessary to develop wide and thin Li metal anodes to increase not only the energy density, but also the design freedom of large-scale Li-metal-based batteries. We solved both issues by developing a novel approach involving the application of calendared stabilized Li metal powder (LiMP) electrodes as anodes. In this study, we fabricated a 21.5 cm wide and 40 μm thick compressed LiMP electrode and investigated the correlation between the compression level and electrochemical performance. A high level of compression (40% compression) physically activated the LiMP surface to suppress the dendritic and mossy Li metal formation at high current densities. Furthermore, as a result of the LiMP self-healing because of electrochemical activation, the 40% compressed LiMP electrode exhibited an excellent cycle performance (reaching 90% of the initial discharge capacity after the 360th cycle), which was improved by more than a factor of 2 compared to that of a flat Li metal foil with the same thickness (90% of the initial discharge capacity after the 150th cycle).

Oxidized Co-Sn nanoparticles as long-lasting anode materials for lithium-ion batteries

Herein, we present the synthesis and systematic comparison of Sn- and Co-Sn-based nanoparticles (NPs) as anode materials for lithium-ion batteries. These nanomaterials were produced via inexpensive routes combining wet chemical synthesis and dry mechanochemical methods (ball milling). We demonstrate that oxidized, nearly amorphous CoSn₂O_x NPs, in contrast to highly crystalline Sn and CoSn₂ NPs, exhibit high cycling stability over 1500 cycles, retaining a capacity of 525 mA h g^-1 (92% of the initial capacity) at a high current density of 1982 mA g^-1. Moreover, when cycled in full-cell configuration with LiCoO₂ as the cathode, such CoSn₂O_x NPs deliver an average anodic capacity of 576 mA h g^-1 over 100 cycles at a current of 500 mA g^-1, with an average discharge voltage of 3.14 V.

Mercaptopropionic Acid-Capped Wurtzite Cu9Sn2Se9 Nanocrystals as High-Performance Anode Materials for Lithium-Ion Batteries

In this research, we provide a simple but sound solution to address the low performance of lithium-ion batteries through preparation of wurtzite Cu₉Sn₂Se₉ nanoparticles with uniform size distribution and morphology via a hot injection colloidal approach as a promising anode material. The Cu₉Sn₂Se₉ nanoparticles anode exhibits superior rate performance and high reversible capacity of 979.8 mAh g^-1 in the 100th cycle at a current density of 100 mA g^-1, which is approximate 2 times of reported Cu-Sn-S framework (563 mA g^-1), 1.5 times of reported pristine Cu₂SnS₃ (621 mA g^-1) and comparable or higher than a number of reported Sn-based nanocomposites based anodes for lithium-ion batteries at the same cycle. The study demonstrate such outstanding properties are attributed to the high structural flexibility of the metal selenide and increased electronic connectivity by colloidal quantum dot ligand exchange procedure associated with mercaptopropionic acid (MPA). In addition, unlike most metal sulfides or selenides, it possesses a stepwise intercalation mechanism during the lithiation/delithiation cycles which is beneficial to buffer against volume variation of the alloy electrode materials. Such findings provide a new and feasible insight into guide the design and manufacturing of high performance lithium-ion batteries for a broad variety of engineering applications.

Ultrasmall Sn nanoparticles embedded in spherical hollow carbon for enhanced lithium storage properties

Ultrasmall Sn nanoparticles (∼5 nm) homogeneously embedded in the shell of spherical hollow carbon show enhanced lithium storage properties with high capacity and a long life.

In situ growth of heterostructured Sn/SnO nanospheres embedded in crumpled graphene as an anode material for lithium ion batteries

Heterostructured Sn/SnO core–shell nanospheres embedded in graphene have been prepared by heating tin oleate coated on the surface of sodium carbonate crystals, and they exhibit excellent electrochemical performance for LIBs.

NiMoO4nanorod deposited carbon sponges with ant-nest-like interior channels for high-performance pseudocapacitors

Monolithic carbon sponges with uniformly deposited NiMoO₄nanorods and ant-nest-like interior channels are reported as elastic electrodes for asymmetric supercapacitors.

Formation of N-Doped Carbon-Coated ZnO/ZnCo2 O4 /CuCo2 O4 Derived from a Polymetallic Metal-Organic Framework: Toward High-Rate and Long-Cycle-Life Lithium Storage

Metal-organic frameworks (MOFs) are very promising self-sacrificing templates for the large-scale fabrication of new functional materials owing to their versatile functionalities and tunable porosities. Most conventional metal oxide electrodes derived from MOFs are limited by the low abundance of incorporated metal elements. This study reports a new strategy for the synthesis of multicomponent active metal oxides by the pyrolysis of polymetallic MOF precursors. A hollow N-doped carbon-coated ZnO/ZnCo₂ O₄ /CuCo₂ O₄ nanohybrid is prepared by the thermal annealing of a polymetallic MOF with ammonium bicarbonate as a pore-forming agent. This is the first report on the rational design and preparation of a hybrid composed of three active metal oxide components originating from MOF precursors. Interestingly, as a lithium-ion battery anode, the developed electrode delivers a reversible capacity of 1742 mAh g^-1 after 500 cycles at a current density of 0.3 mA g^-1 . Furthermore, the material shows large storage capacities (1009 and 667 mAh g^-1 ), even at high current flow (3 and 10 A g^-1 ). The remarkable high-rate capability and outstanding long-life cycling stability of the multidoped metal oxide benefits from the carbon-coated integrated nanostructure with a hollow interior and the three active metal oxide components.

Metallic Sn-Based Anode Materials: Application in High-Performance Lithium-Ion and Sodium-Ion Batteries

With the fast-growing demand for green and safe energy sources, rechargeable ion batteries have gradually occupied the major current market of energy storage devices due to their advantages of high capacities, long cycling life, superior rate ability, and so on. Metallic Sn-based anodes are perceived as one of the most promising alternatives to the conventional graphite anode and have attracted great attention due to the high theoretical capacities of Sn in both lithium-ion batteries (LIBs) (994 mA h g-1) and sodium-ion batteries (847 mA h g-1). Though Sony has used Sn-Co-C nanocomposites as its commercial LIB anodes, to develop even better batteries using metallic Sn-based anodes there are still two main obstacles that must be overcome: poor cycling stability and low coulombic efficiency. In this review, the latest and most outstanding developments in metallic Sn-based anodes for LIBs and SIBs are summarized. And it covers the modification strategies including size control, alloying, and structure design to effectually improve the electrochemical properties. The superiorities and limitations are analyzed and discussed, aiming to provide an in-depth understanding of the theoretical works and practical developments of metallic Sn-based anode materials.