Scalable in Situ Synthesis of Li4Ti5O12/Carbon Nanohybrid with Supersmall Li4Ti5O12 Nanoparticles Homogeneously Embedded in Carbon Matrix

Ultrafine SnO2/Sn Nanoparticles Embedded into an In Situ Generated Meso-/Macroporous Carbon Matrix with a Tunable Pore Size

Ultrafine SnO₂/Sn nanoparticles encapsulated into an adjustable meso-/macroporous carbon matrix have been successfully fabricated by the in situ SiO_x sacrificial strategy. The control over the void space in the carbon matrix effectively improves the accessibility of the SnO₂/Sn toward an electrolyte solution. More importantly, the void space also provides an efficient means to accommodate the mechanical stress caused by the volume change of the SnO₂/Sn over cycles. As a result, the enhanced electrolyte accessibility and suppressed mechanical stress improve the electrochemical performance regarding reversible capacity, cyclic stability, and rate capability. A reversible capacity of 1105 mAh g^-1 is still retained after 290 cycles at 200 mAg^-1, and the capacity still can keep at 107 mAh g^-1 at a high current density of 10 A g^-1.

Enhanced Rate Performance of Lithium-Ion Battery Anodes Using Cobalt Incorporated Carbon Conductive Agent

Lithium-ion battery with enhanced rate performance is of crucial importance for practical applications. Extensive studies on structural design and surface modification of electrode materials to improve the rate performance have...

Impact of CO2 activation on the structure, composition, and performance of Sb/C nanohybrid lithium/sodium-ion battery anodes

Antimony (Sb) has been regarded as one of the most promising anode materials for both lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs) and attracted much attention in recent years. Alleviating the volumetric effect of Sb during charge and discharge processes is the key point to promote Sb-based anodes to practical applications. Carbon dioxide (CO₂) activation is applied to improve the rate performance of the Sb/C nanohybrid anodes caused by the limited diffusion of Li/Na ions in excessive carbon components. Based on the reaction between CO₂ and carbon, CO₂ activation can not only reduce the excess carbon content of the Sb/C nanohybrid but also create abundant mesopores inside the carbon matrix, leading to enhanced rate performance. Additionally, CO₂ activation is also a fast and facile method, which is perfectly suitable for the fabrication system we proposed. As a result, after CO₂ activation, the average capacity of the Sb/C nanohybrid LIB anode is increased by about 18 times (from 9 mA h g^-1 to 160 mA h g^-1) at a current density of 3300 mA g^-1. Moreover, the application of the CO₂-activated Sb/C nanohybrid as a SIB anode is also demonstrated, showing good electrochemical performance.

Spherical Li4Ti5O12/NiO Composite With Enhanced Capacity and Rate Performance as Anode Material for Lithium-Ion Batteries

Compositing with metal oxides is proved to be an efficient strategy to improve electrochemical performance of anode material Li₄Ti₅O₁₂ for lithium-ion batteries. Herein, spherical Li₄Ti₅O₁₂/NiO composite powders have been successfully prepared via a spray drying method. X-ray diffraction and high-resolution transmission electron microscopy results demonstrate that crystal structure of the powders is spinel. Scanning electron microscopy results show that NiO uniformly distributes throughout Li₄Ti₅O₁₂ matrix. It is found that compositing with NiO increases both discharge platform capacity and rate stability of Li₄Ti₅O₁₂. The as-prepared Li₄Ti₅O₁₂/NiO (5%) exhibits a high initial discharge capacity of 381.3 mAh g⁻¹ at 0.1 C, and a discharge capacity of 194.7 mAh g⁻¹ at an ultrahigh rate of 20 C.

CVD-assisted fabrication of hierarchical microparticulate Li2TiSiO5-carbon nanospheres for ultrafast lithium storage

Particular recent interest has been given to the Li₂TiSiO₅ (LTSO) anode material owing to its low lithiation potential (0.28 V vs. Li/Li⁺) and decent theoretical capacity (308 mA h g^-1). However, its poor electronic conductivity (∼10^-7 S m^-1) fundamentally limits the utilization of this material, and current strategies fail to tackle such issues in practical ways. Herein, a hierarchical microparticulate LTSO-carbon composite (LTSO/C) is fabricated by chemical vapor deposition (CVD), where microsized LTSO/C particles assembled from nanospheres guarantee a practical tap density of ∼1.3 g mL^-1. Meanwhile, significantly elevated conductivity of LTSO/C (∼10³ S m^-1) is achieved by a thin layer (15 nm) of graphitic carbon growth on LTSO, which is theoretically catalyzed by the surface functional groups on the parent LTSO. The electrochemical characterization of LTSO/C reveals a superior graphite-like volumetric capacity of 441.1 mA h cm^-3 and Li₄Ti₅O₁₂-like rate capability (120.1 mA h cm^-3 at 4.5 A g^-1), providing inspiring guidance for designing analogous Ti or Si-based compounds for ultrafast lithium storage materials.

A novel experimental approach for nanostructure analysis: simultaneous small-angle X-ray and neutron scattering

Exploiting small-angle X-ray and neutron scattering (SAXS/SANS) on the same sample volume at the same time provides complementary nanoscale structural information in two different contrast situations. Unlike an independent experimental approach, the truly combined SAXS/SANS experimental approach ensures the exactness of the probed samples, particularly for in situ studies. Here, an advanced portable SAXS system that is dimensionally suitable for installation in the D22 zone of ILL is introduced. The SAXS apparatus is based on a Rigaku switchable copper/molybdenum microfocus rotating-anode X-ray generator and a DECTRIS detector with a changeable sample-to-detector distance of up to 1.6 m in a vacuum chamber. A case study is presented to demonstrate the uniqueness of the newly established method. Temporal structural rearrangements of both the organic stabilizing agent and organically capped gold colloidal particles during gold nanoparticle growth are simultaneously probed, enabling the immediate acquisition of correlated structural information. The new nano-analytical method will open the way for real-time investigations of a wide range of innovative nanomaterials and will enable comprehensive in situ studies on biological systems. The potential development of a fully automated SAXS/SANS system with a common control environment and additional sample environments, permitting a continual and efficient operation of the system by ILL users, is also introduced.

Dehydration of Alginic Acid Cryogel by TiCl4 vapor: Direct Access to Mesoporous TiO2 @C Nanocomposites and Their Performance in Lithium-Ion Batteries

A new strategy for the synthesis of mesoporous TiO₂ @C nanocomposites through the direct mineralization of seaweed-derived alginic acid cryogel by TiCl₄ through a solid/vapor reaction pathway is presented. In this synthesis, alginic acid cryogel can have multiple roles; i) mesoporous template, ii) carbon source, and iii) oxygen source for the TiO₂ precursor, TiCl₄ . The resulting TiO₂ @alginic acid composite was transformed either into pure mesoporous TiO₂ by calcination or into mesoporous TiO₂ @C nanocomposites by pyrolysis. By comparing with a nonporous TiO₂ @C composite, the importance of the mesopores on the performance of electrodes for lithium-ion batteries based on mesoporous TiO₂ @C composite was clearly evidenced. In addition, the carbon matrix in the mesoporous TiO₂ @C nanocomposite also showed electrochemical activity versus lithium ions, providing twice the capacity of pure mesoporous TiO₂ or alginic acid-derived mesoporous carbon (A600). Given the simplicity and environmental friendliness of the process, the mesoporous TiO₂ @C nanocomposite could satisfy the main prerequisites of green and sustainable chemistry while showing improved electrochemical performance as a negative electrode for lithium-ion batteries.

Lithium titanate anode for high-performance lithium-ion batteries using octadecylamine and folic acid-functionalized graphene oxide for fabrication of ultrathin lithium titanate nanoflakes and modification of binder

Functionalized graphene oxide creates significant improvement in electrochemical performance of lithium titanate anode due to high conductivity and structural stability.