Silica nanonetwork confined in nitrogen-doped ordered mesoporous carbon framework for high-performance lithium-ion battery anodes

Diatom-Based Artificial Anode-Uniform Coating of Intrinsic Carbon to Enhance Lithium Storage

Pursuing improved electrode materials is essential for addressing the challenges associated with large-scale Li-ion battery applications. Specifically, silicon oxide (SiOx) has emerged as a promising alternative to graphite anodes, despite issues related to volume expansion and rapid capacity degradation. In this study, we synthesized carbon-coated SiOx using diatom biomass derived from artificially cultured diatoms. However, the inherent carbon content from diatoms poses a significant challenge for the electrochemical performance of diatom-based anodes in large-scale applications. Subsequently, we conducted further research and demonstrated excellent performance with a carbon content of 33 wt.% as anodes. Additionally, real-time characterization of the carbonization process was achieved using thermogravimetry coupled with infrared spectroscopy and gas chromatography mass spectrometry (TG-FTIR-GCMS), revealing the emission of CO and C3O2 during carbonization. Furthermore, electrochemical tests of the processed diatom and carbon (PD@C) anode exhibited outstanding rate capability (~500 mAh g-1 at 2 A g-1), high initial Coulomb efficiency (76.95%), and a DLi+ diffusion rate of 1.03 × 10-12 cm2 s-1. Moreover, structural characterization techniques such as HRTEM-SAED were employed, along with DFT calculations, to demonstrate that the lithium storage process involves not only reversible transport in Li2Si2O5 and Li22Si5, but also physical adsorption between the PD and C layers. Exploring the integration of diatom frustules with the intrinsic carbon content in the fabrication of battery anodes may contribute to a deeper understanding of the mechanisms behind their successful application.

A Brief Overview of Silicon Nanoparticles as Anode Material: A Transition from Lithium-Ion to Sodium-Ion Batteries

The successful utilization of silicon nanoparticles (Si-NPs) to enhance the performance of Li-ion batteries (LIBs) has demonstrated their potential as high-capacity anode materials for next-generation LIBs. Additionally, the availability and relatively low cost of sodium resources have a significant influence on developing Na-ion batteries (SIBs). Despite the unique properties of Si-NPs as SIBs anode material, limited study has been conducted on their application in these batteries. However, the knowledge gained from using Si-NPs in LIBs can be applied to develop Si-based anodes in SIBs by employing similar strategies to overcome their drawbacks. In this review, a brief history of Si-NPs' usage in LIBs is provided and discuss the strategies employed to overcome the challenges, aiming to inspire and offer valuable insights to guide future research endeavors.

Insights on microstructural evolution and capacity fade on diatom [Formula: see text] anodes for lithium-ion batteries

[Formula: see text] is a promising material for developing high-capacity anodes for lithium-ion batteries (LIBs). However, microstructural changes of [Formula: see text] anodes at the particle and electrode level upon prolonged cycling remains unclear. In this work, the causes leading to capacity fade on [Formula: see text] anodes were investigated and simple strategies to attenuate anode degradation were explored. Nanostructured [Formula: see text] from diatomaceous earth was integrated into anodes containing different quantities of conductive carbon in the form of either a conductive additive or a nanometric coating layer. Galvanostatic cycling was conducted for 200 cycles and distinctive trends on capacity fade were identified. A thorough analysis of the anodes at selected cycle numbers was performed using a toolset of characterization techniques, including electrochemical impedance spectroscopy, FIB-SEM cross-sectional analysis and TEM inspections. Significant fragmentation of [Formula: see text] particles surface and formation of filigree structures upon cycling are reported for the first time. Morphological changes are accompanied by an increase in impedance and a loss of electroactive surface area. Carbon-coating is found to restrict particle fracture and to increase capacity retention to 66%, compared to 47% for uncoated samples after 200 cycles. Results provide valuable insights to improve cycling stability of [Formula: see text] anodes for next-generation LIBs.

Encapsulating silicon particles by graphitic carbon enables High-performance Lithium-ion batteries

Silicon combines the advantages of high theoretical specific capacity, low potential and natural abundance, which exhibits great promise as an anode for lithium-ion batteries. However, the main challenges associated with Si anode are continuous volume expansion upon cycling and intrinsic low electronic conductivity, leading to sluggish reaction kinetics and rapid capacity fading. Herein we propose a novel in-situ self-catalytic strategy for the growth of highly graphitic carbon to encapsulate Si nanoparticles by chemical vapor deposition, where the magnesiothermic reduction byproducts are used as templates and catalysts for the formation of three-dimensional (3D) conductive network architecture. Benefiting from the improved electronic conductivity and significant suppression of volume expansion, the as-synthesized Si carbon composites exhibit excellent lithium storage capabilities in terms of high specific capacity (2126 mAh g^-1 at 0.1 A g^-1), remarkable rate capability (750 mAh g^-1 at 5 A g^-1), and good cycling stability over 450 cycles. Furthermore, the as-fabricated full cell (Si//Ni-rich LiNi_0.815Co_0.185-xAl_xO₂) shows high energy density of 395.1 Wh kg^-1 and long-term stable cyclability. Significantly, this work demonstrates the effectiveness of in-situ self-catalysis reaction by using magnesiothermic reduction byproducts catalytically derived carbon matrix to encapsulate alloy-type anode material in giving rise to the overall energy storage performance.

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.

Enabling high electrochemical activity of a hollow SiO2 anode by decorating it with ultrafine cobalt nanoparticles and a carbon matrix for long-lifespan lithium ion batteries

Silica is a very promising anode material for lithium-ion batteries, due to its advantages of being resource-rich and having high theoretical specific capacity. However, poor electrochemical activity severely limits its practical application. To solve this issue, a nanosheet-assembled silica hierarchical hollow sphere decorated with ultrafine cobalt nanoparticles and carbon (SiO2/Co/C) is successfully synthesized. The hollow structure can effectively alleviate the volume expansion, shorten the migration distance of lithium ions, and increase the binding site. Furthermore, the carbon matrix and highly active ultrafine cobalt nanoparticles enhance not only the electronic conductivity but also the electrochemical activity (catalyzing the breaking of Si-O and Li-O bonds) of SiO2. The resulting SiO2/Co/C composite has a high reversible capacity of 1160 mA h g-1 at 0.2 A g-1 and still has a specific capacity of 548 mA h g-1 after 1000 cycles at a high current density of 1.0 A g-1. Moreover, the SiO2/Co/C composite also exhibits good electrochemical performance in a full cell.

Carbon/Polymer Bilayer-Coated Si-SiOx Electrodes with Enhanced Electrical Conductivity and Structural Stability

Si-based electrodes offer exceptionally high capacity and energy density for lithium-ion batteries (LIBs),but suffer from poor structural stability and electrical conductivity that hamper their practical applications. To tackle these obstacles, we design a C/polymer bilayer coating deposited on Si-SiO_x microparticles. The inner C coating is used to improve electrical conductivity. The outer C-nanoparticle-reinforced polypyrrole (CNP-PPy) is a polymer matrix composite that can minimize the volumetric expansion of Si-SiO_x and enhance its structural stability during battery operation. Electrodes made of such robust Si-SiO_x@C/CNP-PPy microparticles exhibit excellent cycling performance: 83% capacity retention (794 mAh g^-1) at a 2 C rate after more than 900 cycles for a coin-type half cell, and 80% capacity retention (with initial energy density of 308 Wh kg^-1) after over 1100 cycles for a pouch-type full cell. By comparing the samples with different coatings, an in-depth understanding of the performance enhancement is achieved, i.e., the C/CNP-PPy with cross-link bondings formed in the bilayer coating plays a key role for the improved structural stability. Moreover, a full battery using the Si-SiO_x@C/CNP-PPy electrode successfully drives a car model, demonstrating a bright application prospect of the C/polymer bilayer coating strategy to make future commercial LIBs with high stability and energy density.

Interface Heteroatom-doping: Emerging Solutions to Silicon-based Anodes

Silicon-based composites have been recognized as a promising anode material for high-energy lithium-ion batteries (LIBs). However, the intrinsically low conductivity and the huge volume expansion during lithiation/delithiation progresses impede its further practical applications. In the past decades, numerous efforts have been made for surface and interface modification of Si-based anodes. Among these, doping of active materials with heteroatoms is one promising method to endow silicon many unmatched electrochemical properties. In this review, we focus on the effects of heteroatom doping on the interfacial properties of Si-based anodes, and some typical strategies for the interface doping are highlighted. We aim to give some reference for interfacial doping of Si-based anodes in LIBs.

Nanostructured diatom earth SiO2 negative electrodes with superior electrochemical performance for lithium ion batteries

Diatomaceous earth (DE) is a naturally occurring silica source constituted by fossilized remains of diatoms, a type of hard-shelled algae, which exhibits a complex hierarchically nanostructured porous silica network. In this work, we analyze the positive effects of reducing DE SiO₂ particles to the sub-micrometer level and implementing an optimized carbon coating treatment to obtain DE SiO₂ anodes with superior electrochemical performance for Li-ion batteries. Pristine DE with an average particle size of 17 μm is able to deliver a specific capacity of 575 mA h g⁻¹ after 100 cycles at a constant current of 100 mA g⁻¹, and reducing the particle size to 470 nm enhanced the reversible specific capacity to 740 mA h g⁻¹. Ball-milled DE particles were later subjected to a carbon coating treatment involving the thermal decomposition of a carbohydrate precursor at the surface of the particles. Coated ball-milled silica particles reached stable specific capacities of 840 mA h g⁻¹ after 100 cycles and displayed significantly improved rate capability, with discharge specific capacities increasing from 220 mA h g⁻¹ (uncoated ball-milled SiO₂) to 450 mA h g⁻¹ (carbon coated ball-milled SiO₂) at 2 A g⁻¹. In order to trigger SiO₂ reactivity towards lithium, all samples were subjected to an electrochemical activation procedure prior to electrochemical testing. XRD measurements on the activated electrodes revealed that the initial crystalline silica was completely converted to amorphous phases with short range ordering, therefore evidencing the effective role of the activation procedure.

Diatomaceous earth SiO₂ anodes with superior electrochemical performance are obtained by ball milling, carbon coating and electrochemical activation of SiO₂ particles.

Rational design of the pea-pod structure of SiOx/C nanofibers as a high-performance anode for lithium ion batteries

Pea-pod structured SiO_x/C nanofibers were synthesized by the electrospinning method, whose structure can be controlled by adjusting the addition amounts of organosilica-polymer nanospheres and they exhibit superior electrochemical performance.

Hierarchical porous carbons from polysaccharides carboxymethyl cellulose, bacterial cellulose, and citric acid for supercapacitor

This study reports excellent supercapacitor performance of hierarchical composite porous carbon (HPC) materials successfully fabricated by one-step carbonization and activation process derived from polysaccharides carboxymethyl cellulose, bacterial cellulose, and citric acid. The resultant HPC displayed unique porous nanosheet morphology with high specific surface area (2490 m² g^-1) and rich oxygen content (7.3%). The developed structures with macropores, mesopore walls, micropores, and high oxygen content led to excellent electrochemical performance for electrode of electric double-layer capacitors (EDLCs). In a three-electrode system, the HPC electrode showed a high specific capacitance of 350 F g^-1, good rate performance, and excellent cycling stability. The energy density of supercapacitor based on HPC was comparable to or higher than that of commercially supercapacitors. More importantly, two series-wound devices were easy to light light-emitting diode (LED, 3.0 V). These results suggest that the current material is a promising candidate for low-cost and eco-friendly energy storage devices.

The State of Research Regarding Ordered Mesoporous Materials in Batteries

Ordered mesoporous materials, porous materials with a pore size of 2-50 nm which are prepared via the sol-gel process using surfactant molecular aggregates as a template to assemble channels through the interfacial action of organic and inorganic substances, have recently triggered a heated debate. In addition to applications in the catalytic cracking of heavy oils and residues, the manufacturing of graft materials, the purification of water, the conversion of automobile exhaust, biochips, and the treatment of environmental pollutants via photocatalysts, ordered mesoporous materials have drawn substantial attention in the field of electrochemical energy storage due to advantages such as large specific surface area, uniform and continuously adjustable pore size, and orderly arrangement. Here, a general summary and appraisal of the study of ordered mesoporous materials for batteries in recent years is given, including the synthesis methods, meso/nanostructural features, and electrochemical capabilities of such materials.

Silicon oxides: a promising family of anode materials for lithium-ion batteries

Silicon oxides have been recognized as a promising family of anode materials for high-energy lithium-ion batteries (LIBs) owing to their abundant reserve, low cost, environmental friendliness, easy synthesis, and high theoretical capacity. However, the extended application of silicon oxides is severely hampered by the intrinsically low conductivity, large volume change, and low initial coulombic efficiency. Significant efforts have been dedicated to tackling these challenges towards practical applications. This Review focuses on the recent advances in the synthesis and lithium storage properties of silicon oxide-based anode materials. To present the progress in a systematic manner, this review is categorized as follows: (i) SiO-based anode materials, (ii) SiO2-based anode materials, (iii) non-stoichiometric SiOx-based anode materials, and (iv) Si-O-C-based anode materials. Finally, future outlook and our personal perspectives on silicon oxide-based anode materials are presented.

Titanosilicate Derived SiO2/TiO2@C Nanosheets with Highly Distributed TiO2 Nanoparticles in SiO2 Matrix as Robust Lithium Ion Battery Anode

Carbon-coated SiO₂/TiO₂ (SiO₂/TiO₂@C) nanosheets consisting of TiO₂ nanoparticles uniformly embedded in SiO₂ matrix and a carbon-coating layer are fabricated by using acidified titanosilicate JDF-L1 nanosheets as template and precursor. SiO₂/TiO₂@C has unique structural features of sheetlike nanostructure, ultrafine TiO₂ nanoparticles distributed in SiO₂ matrix, and carbon coating, which can expedite ion diffusion and electron transfer and relieve volume expansion efficiently, and thus, the synergetic combination of these advantages significantly enhances its Li storage capability. As anode of lithium-ion batteries (LIBs), SiO₂/TiO₂@C nanosheets exhibit a high capacity of 998 mAh g^-1 at 100 mA g^-1 after 100 cycles. Moreover, an ultrahigh capacity of 410 mAh g^-1 retains at 2000 mA g^-1 after 400 cycles. A mixed reaction mechanism of capacitance and diffusion-controlled intercalation is revealed by qualitative and quantitative analysis.

Recent advances in functionalized micro and mesoporous carbon materials: synthesis and applications

Functionalized nanoporous carbon materials have attracted the colossal interest of the materials science fraternity owing to their intriguing physical and chemical properties including a well-ordered porous structure, exemplary high specific surface areas, electronic and ionic conductivity, excellent accessibility to active sites, and enhanced mass transport and diffusion. These properties make them a special and unique choice for various applications in divergent fields such as energy storage batteries, supercapacitors, energy conversion fuel cells, adsorption/separation of bulky molecules, heterogeneous catalysts, catalyst supports, photocatalysis, carbon capture, gas storage, biomolecule detection, vapour sensing and drug delivery. Because of the anisotropic and synergistic effects arising from the heteroatom doping at the nanoscale, these novel materials show high potential especially in electrochemical applications such as batteries, supercapacitors and electrocatalysts for fuel cell applications and water electrolysis. In order to gain the optimal benefit, it is necessary to implement tailor made functionalities in the porous carbon surfaces as well as in the carbon skeleton through the comprehensive experimentation. These most appealing nanoporous carbon materials can be synthesized through the carbonization of high carbon containing molecular precursors by using soft or hard templating or non-templating pathways. This review encompasses the approaches and the wide range of methodologies that have been employed over the last five years in the preparation and functionalisation of nanoporous carbon materials via incorporation of metals, non-metal heteroatoms, multiple heteroatoms, and various surface functional groups that mostly dictate their place in a wide range of practical applications.

Nitrogen-rich sandwich-like carbon nanosheets as anodes with superior lithium storage properties

Nitrogen-rich sandwich-like carbon nanosheets used as anodes for LIBs exhibited high discharge capacity and remarkable rate capability.

Self-assembly synthesis of nitrogen-doped mesoporous carbons used as high-performance electrode materials in lithium-ion batteries and supercapacitors

Guanine was, for the first time, used as a nitrogen source during the synthesis of nitrogen-doped porous carbons (NMCs) with enhanced electrochemical performance.

Strong contribution of pore morphology to the high-rate electrochemical performance of lithium-ion batteries

The interconnected ordered pore channels facilitate faster permeation of Li⁺ ions than the isolated ordered pore channels.

Flour food waste derived activated carbon for high-performance supercapacitors

Activated carbon was prepared by carbonization of flour food waste residue and subsequent KOH activation. It shows great prospects in high-performance supercapacitor applications.

Multi-dimensional construction of a novel active yolk@conductive shell nanofiber web as a self-standing anode for high-performance lithium-ion batteries

A novel active yolk@conductive shell nanofiber web with a unique synergistic advantage of various hierarchical nanodimensional objects including the 0D monodisperse SiO2 yolks, the 1D continuous carbon shell and the 3D interconnected non-woven fabric web has been developed by an innovative multi-dimensional construction method, and thus demonstrates excellent electrochemical properties as a self-standing LIB anode.

Nitrogen-doped dual mesoporous carbon for the selective oxidation of ethylbenzene

A nanocasting method to fabricate nitrogen-doped dual mesoporous carbon is proposed by the carbonization of nitrile functional ionic liquid (FIL) grafted SBA-15 for the first time. These carbon materials have high nitrogen content (12.8%), large specific surface areas (763 m(2) g(-1)) and uniform rod morphologies, which are derived from FILs grafted on the surface of SBA-15. Furthermore, by adjusting the impregnation amount of ionic liquids on SBA-15, pore structures of these carbon materials can be adjusted from single to dual mesopores. The developed dual mesoporous carbon materials exhibit good catalytic performance in the selective oxidation of ethylbenzene, ascribed to the promoting effects of nitrogen-doping, high surface area and dual mesostructure. It may be concluded that the dual mesostructure has an advantage over a single mesostructure to obtain a fast mass transport rate, resulting in higher acetophenone yield.

A plum-pudding like mesoporous SiO2/flake graphite nanocomposite with superior rate performance for LIB anode materials

A novel kind of plum-pudding like mesoporous SiO₂ nanospheres (MSNs) and flake graphite (FG) nanocomposite (pp-MSNs/FG) was designed and fabricated via a facile and cost-effective hydrothermal method.

Highly stable cycling of a lead oxide/copper nanocomposite as an anode material in lithium ion batteries

Nanostructure composites of PbO/Cu–C were synthesized byin situsolvothermal synthesis and heat treatment of PbO/Cu with PVP, used as lithium battery anodes. It exhibits >90% capacity retention after 9500 cycles at a current density of 5.5 A g⁻¹.