Enhancing the Lithium Storage Performance of Graphene/SnO2 Nanorods by a Carbon-Riveting Strategy

Interfacial engineering in SnO2-embedded graphene anode materials for high performance lithium-ion batteries

Tin dioxide is regarded as an alternative anode material rather than graphite due to its high theoretical specific capacity. Modification with carbon is a typical strategy to mitigate the volume expansion effect of SnO2 during the charge process. Strengthening the interface bonding is crucial for improving the electrochemical performance of SnO2/C composites. Here, SnO2-embedded reduced graphene oxide (rGO) composite with a low graphene content of approximately 5 wt.% was in situ synthesized via a cetyltrimethylammonium bromide (CTAB)-assisted hydrothermal method. The structural integrity of the SnO2/rGO composite is significantly improved by optimizing the Sn-O-C electronic structure with CTAB, resulting a reversible capacity of 598 mAh g-1 after 200 cycles at a current density of 1 A g-1. CTAB-assisted synthesis enhances the rate performance and cyclic stability of tin dioxide/graphene composites, and boosts their application as the anode materials for the next-generation lithium-ion batteries.

Insight into Reversible Conversion Reactions in SnO2 -Based Anodes for Lithium Storage: A Review

Various anode materials have been widely studied to pursue higher performance for next generation lithium ion batteries (LIBs). Metal oxides hold the promise for high energy density of LIBs through conversion reactions. Among these, tin dioxide (SnO₂ ) has been typically investigated after the reversible lithium storage of tin-based oxides is reported by Idota and co-workers in 1997. Numerous in/ex situ studies suggest that SnO₂ stores Li⁺ through a conversion reaction and an alloying reaction. The difficulty of reversible conversion between Li₂ O and SnO₂ is a great obstacle limiting the utilization of SnO₂ with high theoretical capacity of 1494 mA h g^-1 . Thus, enhancing the reversibility of the conversion reaction has become the research emphasis in recent years. Here, taking SnO₂ as a typical representative, the recent progress is summarized and insight into the reverse conversion reaction is elaborated. Promoting Li₂ O decomposition and maintaining high Sn/Li₂ O interface density are two effective approaches, which also provide implications for designing other metal oxide anodes. In addition, some in/ex situ characterizations focusing on the conversion reaction are emphatically introduced. This review, from the viewpoint of material design and advanced characterizations, aims to provide a comprehensive understanding and shed light on the development of reversible metal oxide electrodes.

Diverse-shaped tin dioxide nanoparticles within a plastic waste-derived three-dimensional porous carbon framework for super stable lithium-ion storage

Tin dioxides (SnO₂) inserted into carbons to serve as anodes for rechargeable lithium-ion batteries are known to improve their cycling stability. However, studies on diverse-shaped SnO₂ nanoparticles within a porous carbon matrix for super stable lithium-ion storage are rare. Herein, a hollow carbon sphere/porous carbon flake (HCS/PCF) framework is fabricated through template carbonization of plastic waste. By changing the doping mechanism and tuning the loading content, nano SnO₂ spheres and cubes as well as bulk SnO₂ flakes and blocks are in-situ grown within the HCS/PCF. Then, the as-prepared hybrids with built-in various morphological SnO₂ nanoparticles serve as anodes towards advanced lithium-ion batteries. Notably, HCS/PCF embedded with nano SnO₂ spheres and cubes anodes possess superb long-term cycling stability (~0.048% and ~0.05% average capacitance decay per cycle at 1 A/g over 400 cycles) with high reversible specific capacities of 0.45 and 0.498 Ah/g after 1000 cycles at 5 A/g. The ultra-stabilized Li⁺ storage is attributed to the effective mitigation of nano SnO₂ spheres/cubes volume expansion, originating from the compact SnO₂ yolk-HCS/PCF shell construction. This study paves a general strategy for disposing of polymeric waste to produce SnO₂ core-carbon shell anodes for super stable lithium-ion storage.

Carbon-coated SnO2 riveted on a reduced graphene oxide composite (C@SnO2/RGO) as an anode material for lithium-ion batteries

The research on graphene-based anode materials for high-performance lithium-ion batteries (LIBs) has been prevalent in recent years. In the present work, carbon-coated SnO₂ riveted on a reduced graphene oxide sheet composite (C@SnO₂/RGO) was fabricated using GO solution, SnCl₄, and glucose via a hydrothermal method after heat treatment. When the composite was exploited as an anode material for LIBs, the electrodes were found to exhibit a stable reversible discharge capacity of 843 mA h g⁻¹ at 100 mA g⁻¹ after 100 cycles with 99.5% coulombic efficiency (CE), and a specific capacity of 485 mA h g⁻¹ at 1000 mA g⁻¹ after 200 cycles; these values were higher than those for a sample without glucose (SnO₂/RGO) and a pure SnO₂ sample. The favourable electrochemical performances of the C@SnO₂/RGO electrodes may be attributed to the special double-carbon structure of the composite, which can effectively suppress the volume expansion of SnO₂ nanoparticles and facilitate the transfer rates of Li⁺ and electrons during the charge/discharge process.

The combined action of GO and glucose makes the SnO₂ dispersed uniformly. The synergistic effect of the unique double-carbon structure can effectively improve the electrical conductivity of the SnO₂ and strengthen lithium storage capability.

Superior and Reversible Lithium Storage of SnO2/Graphene Composites by Silicon Doping and Carbon Sealing

The poor cycle stability and reversibility seriously hinder the widespread application of SnO₂ materials as anodes for lithium-ion batteries (LIBs). A novel sandwich-architecture composite of Si-doped SnO₂ nanorods and reduced graphene oxide with carbon sealing (Si-SnO₂@G@C) is engineered and fabricated by a facile two-step hydrothermal process and subsequent annealing treatment, which exhibit not only extraordinary rate performance and ultrahigh reversible capacity but also excellent cycle stability and high electrical conductivity as the anode of LIBs. The Si-doped SnO₂ nanoparticles on the surface of graphene were firmly wrapped in the C-coating and formed a porous sandwich structure, which can efficiently prevent the Sn nanoparticles from aggregation and provide more extra space for accommodating the volume variations and more active sites for reactions. The carbon layer also blocks the direct contact of the SnO₂ nanorods with electrolyte and prevents the graphene nanosheets from the restacking. More importantly, the reversibility of lithiation/delithiation reactions can be remarkably improved by the doping silicon. The doped Si not only accelerates the diffusion of Li⁺ but also brings a significant increase in the specific capacity. As a consequence, the Si-SnO₂@G@C nanocomposite can maintain a high capacity of 654 mAh/g at 2 A/g even after 1200 cycles with negligible capacity loss and excellent reversibility with a Coulombic efficiency retention over 99%, which can be capable of the alternative to commercial graphite anodes. This work provides a new strategy for the reasonable design of advanced anode materials with superior and reversible lithium storage capacity.

Tin Oxide Based Nanomaterials and Their Application as Anodes in Lithium-Ion Batteries and Beyond

Herein, recent progress in the field of tin oxide (SnO2 )-based nanosized and nanostructured materials as conversion and alloying/dealloying-type anodes in lithium-ion batteries and beyond (sodium- and potassium-ion batteries) is briefly discussed. The first section addresses the importance of the initial SnO2 micro- and nanostructure on the conversion and alloying/dealloying reaction upon lithiation and its impact on the microstructure and cyclability of the anodes. A further section is dedicated to recent advances in the fabrication of diverse 0D to 3D nanostructures to overcome stability issues induced by large volume changes during cycling. Additionally, the role of doping on conductivity and synergistic effects of redox-active and -inactive dopants on the reversible lithium-storage capacity and rate capability are discussed. Furthermore, the synthesis and electrochemical properties of nanostructured SnO2 /C composites are reviewed. The broad research spectrum of SnO2 anode materials is finally reflected in a brief overview of recent work published on Na- and K-ion batteries.

Extraordinary lithium ion storage capability achieved by SnO2 nanocrystals with exposed {221} facets

Rational design of SnO2 nanomaterials with superior architectures and excellent electrochemical properties is highly desirable for lithium ion storage. Here, several SnO2 nanoparticles with different exposed crystal planes, such as {101}, {110} and {221} facets, are developed and further embedded into graphene/carbon nanotube (G/CNT) networks, achieving highly conductive carbon/SnO2 films (C/SnO2) with homogeneous dispersion of SnO2 nanoparticles. Three-dimensional (3D) G/CNT networks with highly porous structures and electronic contacts with imbedded SnO2 nanoparticles provide excellent pathways for transfer of electrons and ions and further buffer structural changes of SnO2 nanocrystals during lithium-ion insertion/extraction processes. Close contact between G/CNT matrix and embedded SnO2 nanoparticles ensures that all high-energy {221} facets of SnO2 are exploited during rapid electrochemical reactions. The high electrical conductivity of G/CNT networks can further prevent pulverization of nanostructured SnO2. As a result, C/SnO2 film with 90% content of octahedral SnO2 nanocrystals (C/SnO2-O (90%)) exhibits superior reversible specific capacity of 1008 mA h g-1 at 0.1 A g-1, excellent rate capability, low internal resistance and long-term cycling stability for 1000 cycles. These results further confirm that SnO2 nanocrystals with high-energy {221} facets can provide numerous active sites for lithium ion storage than other SnO2 nanomaterials.