Low-content SnO2 nanodots on N-doped graphene: lattice-confinement preparation and high-performance lithium/sodium storage

Rational construction of nanosized anode nanomaterials is crucial to enhance the electrochemical performance of lithium-/sodium-ion batteries (LIBs/SIBs). Various anode nanoparticles are created mainly via templating surface confinement, or encapsulation within precursors (such as metal-organic frameworks). Herein, low-content SnO₂ nanodots on N-doped reduced graphene oxide (SnO₂@N-rGO) were prepared as anode nanomaterials for LIBs and SIBs, via a distinctive lattice confinement of a CoAlSn-layered double hydroxide (CoAlSn-LDH) precursor. The SnO₂@N-rGO composite exhibits the advantagous features of low-content (17.9 wt%) and uniform SnO₂ nanodots (3.0 ± 0.5 nm) resulting from the lattice confinement of the Co and Al species to the surrounded Sn within the same crystalline layer, and high-content conductive rGO. The SnO₂@N-rGO composite delivers a highly reversible capacity of 1146.2 mA h g^-1 after 100 cycles at 0.1 A g^-1 for LIBs, and 387 mA h g^-1 after 100 cycles at 0.1 A g^-1 for SIBs, outperforming N-rGO. Furthermore, the dominant capacitive contribution and the rapid electronic and ionic transfer, as well as small volume variation, all give rise to the enhancement. Precursor-based lattice confinement could thus be an effective strategy for designing and preparing uniform nanodots as anode nanomaterials for electrochemical energy storage.

Cumulative effects of doping on Sn3O4 structure and electrode performance for rechargeable sodium-ion batteries

Interconnected nanoflakes of modified Sn3O4 are capable of providing fast carrier transmission dynamics and outstanding structural integrity, suggesting the feasibility of the current framework for sodium-ion storage.

Layered Niobium Oxide Hydrate Anode with Excellent Performance for Lithium-Ion Batteries

Benefiting from the advantages of cost-effectiveness and sustainability, lithium-ion batteries (LIBs) are recognized as a next-generation energy technology with great development potential. Herein, niobium oxide hydrate (H₃ONb₃O₈) synthesized by a facile and inexpensive solvothermal method is proposed as the anode of LIBs. It is a layered two-dimensional material composed of negatively charged two-dimensional lamellae and positively charged interlayer hydronium ions. The former consist of NbO₆ octahedral units connected by bridging oxygen. Because of the mutual effect of hydronium ions and niobium oxide quantum dots, niobium oxide hydrate exhibits excellent electrochemical activity when used as an anode material. This compound is first applied to lithium-ion batteries, obtaining a high specific capacity (1232 mAh g^-1) at 100 mA g^-1 and maintaining an outstanding performance after 200 cycles. Therefore, this work not only proposes a simple preparation method of niobium oxide hydrate but also expands the variety of high-performance anode materials.

A Nanosheet-Assembled SnO2-Integrated Anode

There is an ever-increasing trend toward bendable and high-energy-density electrochemical storage devices with high strength to fulfil the rapid development of flexible electronics, but they remain a great challenge to be realised by the traditional slurry-casting fabrication processes. To overcome these issues, herein, a facile strategy was proposed to design integrating an electrode with flexible, high capacity, and high tensile strength nanosheets with interconnected copper micro-fibre as a collector, loaded with a novel hierarchical SnO₂ nanoarchitecture, which were assembled into core-shell architecture, with a 1D micro-fibre core and 2D nanosheets shell. When applied as anode materials for LIBs, the resultant novel electrode delivers a large reversible specific capacity of 637.2 mAh g^-1 at a high rate of 1C. Such superior capacity may benefit from rational design based on structural engineering to boost synergistic effects of the integrated electrode. The outer shell with the ultrathin 2D nanoarchitecture blocks can provide favourable Li⁺ lateral intercalation lengths and more beneficial transport routes for electrolyte ions, with sufficient void space among the nanosheets to buffer the volume expansion. Furthermore, the interconnected 1D micro-fibre core with outstanding metallic conductivity can offer an efficient electron transport pathway along axial orientation to shorten electron transport. More importantly, the metal's remarkable flexibility and high tensile strength provide the hybrid integrated electrode with strong bending and stretchability relative to sintered carbon or graphene hosts. The presented strategy demonstrates that this rational nanoarchitecture design based on integrated engineering is an effective route to maintain the structural stability of electrodes in flexible LIBs.

A nanostructured SnO2/Ni/CNT composite as an anode for Li ion batteries

A SnO₂/Ni/CNT nanocomposite was synthesized using a simple one-step hydrothermal method followed by calcination. A structural study via XRD shows that the tetragonal rutile structure of SnO₂ is maintained. Further, X-ray photoelectron spectroscopy (XPS) and Raman studies confirm the existence of SnO₂ along with CNTs and Ni nanoparticles. The electrochemical performance was investigated via cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and galvanostatic charge–discharge measurements. The nanocomposite has been used as an anode material for lithium-ion batteries. The SnO₂/Ni/CNT nanocomposite exhibited an initial discharge capacity of 5312 mA h g⁻¹ and a corresponding charge capacity of 2267 mA h g⁻¹ during the first cycle at 50 mA g⁻¹. Pristine SnO₂ showed a discharge/charge capacity of 1445/636 mA h g⁻¹ during the first cycle at 50 mA g⁻¹. This clearly shows the effects of the optimum concentrations of CNTs and Ni. Further, the nanocomposite (SnNiCn) shows a discharge capacity as high as 919 mA h g⁻¹ after 210 cycles at a current density of 400 mA g⁻¹ in a Li-ion battery set-up. Thus, the obtained capacity from the nanocomposite is much higher compared to pristine SnO₂. The higher capacity in the nanoheterostructure is due to the well-dispersed nanosized Ni-decorated stabilized SnO₂ along with the CNTs, avoiding pulverization as a result of the volumetric change of the nanoparticles being minimized. The material accommodates huge volume expansion and avoids the agglomeration of nanoparticles during the lithiation and delithiation processes. The Ni nanoparticles can successfully inhibit Sn coarsening during cycling, resulting in the enhancement of stability during reversible conversion reactions. They ultimately enhance the capacity, giving stability to the nanocomposite and improving performance. Additionally, the material exhibits a lower Warburg coefficient and higher Li ion diffusion coefficient, which in turn accelerate the interfacial charge transfer process; this is also responsible for the enhanced stable electrochemical performance. A detailed mechanism is expressed and elaborated on to provide a better understanding of the enhanced electrochemical performance.

SnO₂/Ni/CNT nanocomposite approach has been demonstrated which confers shielding against volume expansion due to the use of optimum % of Ni & CNT exhibiting superior cycling stability and rate capabilities of the stable electrode structure.

SnO2 Nanoflower-Nanocrystalline Cellulose Composites as Anode Materials for Lithium-Ion Batteries

One of the biggest challenges in the commercialization of tin dioxide (SnO₂₎-based lithium-ion battery (LIB) electrodes is the volume expansion of SnO₂ during the charge-discharge process. Additionally, the aggregation of SnO₂ also deteriorates the performance of anode materials. In this study, we prepared SnO₂ nanoflowers (NFs) using nanocrystalline cellulose (CNC) to improve the surface area, prevent the particle aggregation, and alleviate the change in volume of LIB anodes. Moreover, CNC served not only as the template for the synthesis of the SnO₂ NFs but also as a conductive material, after annealing the SnO₂ NFs at 800 °C to improve their electrochemical performance. The obtained CNC-SnO₂NF composite was used as an active LIB electrode material and exhibited good cycling performance and a high initial reversible capacity of 891 mA h g^-1, at a current density of 100 mA g^-1. The composite anode could retain 30% of its initial capacity after 500 charge-discharge cycles.