Low Specific Capacity Research Articles

Electrochemical performance of Li-ion battery-based porous silicon nanowires (PSiNWs) decorated with silver nanoparticles

ABSTRACT In recent years, silicon-based materials have attracted great interest for their use as anode in lithium-ion batteries due to their low charging potential and high specific capacity. Morever, silicon nanowires (SiNWs) have been shown to successfully solve the volume-expansion problem by providing free volumes to accommodate silicon expansion. In this work, we fabricated porous silicon nanowires (PSiNWs) on an n-type silicon wafer using a single low-cost metal-assisted chemical etching (MACE) step. Then, the formed (PSiNWs) nanowires were extracted and covered with silver nanoparticles. To reveal the underlying physical and electrochemical mechanisms, we also process a sample of comparative porous silicon nanowires, ranging in diameter from 50 to 100 nm and having a porosity of approximately 60%. The specific capacity is approximately 3635 mA h g−1 with a Coulomb efficiency of 98.8% in the first charge/discharge cycle for PSiNWs/AgNPs, while PSiNWs exhibit low capacity during the first cycle. This study highlights the design of porous silicon nanowires with a large specific surface area and the structural modification of the surface with silver nanoparticles.

Low-defect potassium vanadyl hexacyanoferrate cathode material with high specific capacity for aqueous zinc ion batteries

Prussian blue analogues (PBAs) are considered to be one of the most promising cathode materials for aqueous zinc-ion batteries (AZIBs). However, the low specific capacity due to defects and low activity has become the major problem limiting their application. In this work, a potassium vanadyl hexacyanoferrate K0.37VO[Fe(CN)6]0.61·2.6H2O was synthesized by ethanol-assisted co-precipitation. Controlled growth by ethanol addition results in smaller particle size and fewer defects in K0.37VO[Fe(CN)6]0.61·2.6H2O, leading to excellent zinc ion storage properties. The K0.37VO[Fe(CN)6]0.61·2.6H2O cathode material exhibits a high specific capacity of 190 mAh·g−1 at 0.1 A·g−1 and an outstanding rate performance of 160 mAh·g−1 at 2 A·g−1. Ex-situ characterization technologies reveal that the zinc-ion storage process is involve with redox reaction of Fe2+/Fe3+ and V3+/V4+/V5+, as well as phase transition.

Flux Synthesis of Robust Polyimide Covalent Organic Frameworks with High-Density Redox Sites for Efficient Proton Batteries.

Aqueous proton batteries are attracting increasing attention in the large-scale next-generation energy storage field. However, the electrode materials for proton batteries often suffer from low specific capacity and unsatisfactory cycle durability. Herein, we synthesize two highly crystalline and robust polyimide covalent organic frameworks (COFs) through a solvent-free flux synthesis approach with benzoic acid as a flux and catalyst. The as-synthesized COFs possess enriched redox-active sites for proton storage and intrinsic Grotthuss proton conduction, rendering them ideal candidates for proton electrode materials. The optimal COF electrodes achieve a high specific capacity of 180 mAh/g at 0.1 A/g, among the highest COF-based proton batteries, and exhibit an outstanding rate capability of up to 100 A/g and long-term cycling stability with capacity retention of 99% after 5000 cycles at 5 A/g. The assembled full cells deliver a specific capacity of 150 mAh/g at 0.2 A/g with a maximum energy density of 72 Wh/kg and a maximum supercapacitor-level power density of 64 kW/kg, surpassing all reported COF-based systems. This work paves a new avenue for the design of electrode materials for aqueous proton batteries with high energy density, power density, rate capability and long-term cycling stability.

Polymeric Iodine Transport Layer Enabled High Areal Capacity Dual Plating Zinc‐Iodine Battery

Iodine cathode in aqueous battery has drawn great attention due to its high energy density and high safety. However, iodine has extremely low conductivity of 1×10‐7 S cm‐1, which usually results in low specific capacity. In this work, a PVA‐hydrogel layer was designed to enhance the areal capacity of zinc‐iodine cell. The areal capacity of PVA‐hydrogel layer modified CNT cathode showed twice as higher capacity than that of pure CNT film in a dual‐plating cell, The significant enhancement of the capacity was attributed to the fast iodine transport in the PVA‐hydrogel layer. Besides, the strong interaction between PVA chain and polyiodide anions prevented the shuttle effect. The PVA modified CNT cathode could stably operate for over 3000 hours with remarkably higher capacity and cycle life. We analyzed the uniquely fast transport behavior of polyiodides in PVA hydrogel by in‐situ Raman spectroscopy, in‐situ optical micrography, as well as DFT calculations. It was found that the strong binding force together with lower dissociation energy of iodine on PVA chain is the dominate reason for reduced shuttle effect and fast polyiodide transport. As a result, the assembled PVA‐I2 pouch cells showed excellent performance in both dual‐plating cells and conventional‐type cells.

Polymeric Iodine Transport Layer Enabled High Areal Capacity Dual Plating Zinc-Iodine Battery.

Iodine cathode in aqueous battery has drawn great attention due to its high energy density and high safety. However, iodine has extremely low conductivity of 1×10-7 S cm-1, which usually results in low specific capacity. In this work, a PVA-hydrogel layer was designed to enhance the areal capacity of zinc-iodine cell. The areal capacity of PVA-hydrogel layer modified CNT cathode showed twice as higher capacity than that of pure CNT film in a dual-plating cell, The significant enhancement of the capacity was attributed to the fast iodine transport in the PVA-hydrogel layer. Besides, the strong interaction between PVA chain and polyiodide anions prevented the shuttle effect. The PVA modified CNT cathode could stably operate for over 3000 hours with remarkably higher capacity and cycle life. We analyzed the uniquely fast transport behavior of polyiodides in PVA hydrogel by in-situ Raman spectroscopy, in-situ optical micrography, as well as DFT calculations. It was found that the strong binding force together with lower dissociation energy of iodine on PVA chain is the dominate reason for reduced shuttle effect and fast polyiodide transport. As a result, the assembled PVA-I2 pouch cells showed excellent performance in both dual-plating cells and conventional-type cells.

Electrospun Mesoporous Ni0.5Zn0.5Fe2O4 - CNT - Hollow Carbon Ternary Composite Nanofibers as High Performance Electrodes for Advanced Symmetric Supercapacitors.

Spinel ferrites have attracted considerable interest in energy storage systems due to their unique magnetic, electrical and catalytic properties. However, they suffer from poor electronic conductivity and low specific capacity. We have addressed this limitation by synthesizing composite hollow carbon nanofibers (HCNF) embedded with nanostructured Nickel Zinc Ferrite (NZF) and Multiwalled carbon nanotubes (CNT), through coaxial electrospinning. These ternary composite nanofibers NZF-CNT-HCNF have a high specific capacity of 833 C g-1 at a current density of 1 A g-1 and have a capacity retention of 90 % after 3000 cycles. Their performance is much better than pure NZF fibers (180 C g-1) or hollow carbon nanofibers (96 C g-1), suggesting synergy between various constituents of the composite. A symmetric supercapacitor fabricated from NZF-CNT-HCNF composite nanofibers (30 % NZF) has a high specific capacity of 302 C g-1 (302 A g-1) at a current density of 1 A g-1 and has a capacity retention of 95 % after 5000 cycles. At the same current density, the device has a high energy density of 39 Whkg-1 and power density of 1000 Wkg-1 at a current density of 1 A g-1. This performance can be attributed to the high specific surface area (776 m2 g-1), mesoporosity (pore size ~4 nm), interconnectedness of the nanofibers and high electrical conductivity of CNTs. These fibers can be used as light-weight high performance electrode materials in advanced energy storage devices.

Design, perspectives, and challenges of modification strategies for alkali metal anodes

Abstract. The alkali metal anode has emerged as a focal point of research due to its extremely low oxidation-reduction potential and high theoretical specific capacity. However, challenges such as unstable solid electrolyte interphase (SEI), infinite volume expansion, and uncontrollable dendrite growth result in low coulombic efficiency and irreversible losses during the deposition and stripping processes. To address these issues, various effective strategies have been proposed to protect the alkali metal anode and achieve dendrite-free growth. In this review, we summarize recent advancements in enhancement strategies for alkali metal anodes, including the construction of three-dimensional current collectors and interface engineering. Specifically, we delve into the development of carbon-based current collectors with various dimensions and structures and the application of interface engineering techniques to tackle the challenges of unstable SEI, volume changes, and dendrite growth. Furthermore, we explore advanced characterization techniques that provide deeper insights into the reaction mechanisms and behavior of these enhancement strategies. Finally, we discuss the current limitations and future research directions in protecting alkali metal anodes, aiming to provide valuable insights into the study of dendrite growth and the development of effective protection strategies for alkali metal anodes.

Understanding the Wettability of C1N1 (Sub)Nanopores: Implications for Porous Carbonaceous Electrodes.

Understanding how water interacts with nanopores of carbonaceous electrodes is crucial for energy storage and conversion applications. A high surface area of carbonaceous materials does not necessarily need to translate to a high electrolyte-solid interface area. Herein, we study the interaction of water with nanoporous C1N1 materials to explain their very low specific capacitance in aqueous electrolytes despite their high surface area. Water was used to probe chemical environments, provided by pores of different sizes, in 1H MAS NMR experiments. We observe that regardless of their high hydrophilicity, only a negligible portion of water can enter the nanopores of C1N1, in contrast to a reference pure carbon material with a similar pore structure. The common paradigm that water easily enters hydrophilic pores does not apply to C1N1 nanopores below a few nanometers. Calorimetric and sorption experiments demonstrated strong water adsorption on the C1N1 surface, which restricts water mobility across the interface and impedes its penetration into the nanopores.

Regulation plateau capacity and initial coulombic efficiency of furfural residues-derived hard carbon via components engineering

The scale-up application of biomass-based hard carbon (HC) in sodium-ion battery (SIB) is hampered by low initial coulombic efficiency (ICE) and specific capacity, especially for the plateau capacity. By taking advantage of furfural residues (FRs), which are mainly constructed with lignin and cellulose, a component modulation engineering strategy is adopted to prepare high performance HC. In this work, the microstructure of FR-derived HCs can be well-regulated after component modulation. Specifically, the introduction of oxygen functional groups during low-temperature oxidation process promotes the recombination of cellulose and lignin in FRs and produces more C=O in oxidized FRs, which is favorable to suppress the carbon structure from melting and rearranging during the high-temperature carbonization process, leading to a well-balanced pseudo-graphitized/disordered microstructure and excellent corresponding electrochemical performance. Experiment results reveal that the sample underwent component engineering delivers a high capacity of 302.5 mAh g−1 and excellent ICE of 90.9 %, which are higher than that of the sample direct carbonized (225.0 mAh g−1 and 75.6 %). Notably, the plateau capacity increases from 147.0 mAh g−1 to 204.2 mAh g−1, accounting for nearly 100 % of the reversible capacity increase. Our work provides a new insight of microstructure regulation of biowaste-based HC with high electrochemical performance.

Coupling (NixCo1-x)0.85Se with N-doped MoSe2 for hybrid supercapacitors with remarkable cyclic durability

Despite being a novel supercapacitive material, the widespread application of layered molybdenum diselenide has been hindered by its low specific capacity, significant volume changes during electrochemical reactions, and slow kinetics. In this study, we successfully combined (NixCo1-x)0.85Se nanoparticles with N-MoSe2 to create (NixCo1-x)0.85Se/N-MoSe2 hybrids (labeled as AxB1-xC). The electrochemical performance of AxB1-xC was dramatically improved due to the synergistic effects between nickel and cobalt, as well as between (NixCo1-x)0.85Se and N-MoSe2. Among the various AxB1-xC electrodes, the A0.8B0.2C electrode exhibited the best electrochemical performance when the Ni/Co ratio was 0.8/0.2. It provided a specific capacity of 397.9 C g−1 at 0.5 A g−1 and retained 220.0 C g−1 after 2,000 cycles at 10 A g−1. Furthermore, we constructed an A0.8B0.2C//AC hybrid supercapacitor to assess its energy storage capability. The A0.8B0.2C//AC device achieved a specific capacitance of 72.6 F g−1 at 0.5 A g−1 with an energy density of 25.8 Wh kg−1 at 400 W kg−1. The capacitive retention of the A0.8B0.2C//AC device was 92.9 % after 40,000 cycles at 3 A g−1. Impressively, a self-constructed A0.8B0.2C//AC device could power a timer for about 24 min, demonstrating its potential for practical applications.

A versatile opened hollow carbon sphere with highly loaded antimony alloy for ultra-stable potassium-ion storage

Carbon materials meet the stringent practical requirements for anodes for potassium-ion batteries (PIBs) due to their abundance and chemical stability. The major issue of carbon-based anodes is the low specific capacity and poor cyclic stability. Equally importantly, scalable synthesis approaches for electrodes are highly desired for the future application in large-scale energy storage systems. Herein, we developed a novel composite of Sb encapsulated in N/P co-doped opened hollow carbon spheres (N/POHCs) with high Sb loading through a simple carbonization and subsequent impregnation process. Beneficial from the virtue of abundant pyridinic-N−P bonding and opened hollow spherical structure advantages, N/POHCs exhibit much lower diffusion barrier than that of pure carbon, prominent Sb carrier capability, as well as the extraordinary resistance to volume expansion. The resulting Sb@N/POHCs composite delivers a high specific capacity of 533.3 mAh g−1 at 0.1 A g−1 with an initial Coulombic efficiency of 83 %, and can maintain a specific capacity of 345 mAh g−1 at 1 A g−1 after 4000 cycles. This work provides rational structure design with universal carrier capability of active materials to achieve high-capacity and long cycle life anode for advanced PIBs accompanied by the potential for large-scale production.

Experimental investigations on strength and microstructural characteristics of air-cell impregnated light weight concrete

Concrete structures have high massive building materials than steel structures and possess very low thermal conductivity and high specific heat capacity. However, an efficient approach to reducing high production cost and structural weight of concrete elements without impacting their strength evolve as a growing necessity that leads to innovation in the Light weight concrete (LWC) fields such as aerated concrete and foamed concrete. Those large bubbles seem highly likely to get a break, move upwards through buoyancy and may get lost, while concrete has been mixed, transported, placed and vibrated. Hence to prevent increased bubble spacing, and air loss and to increase concrete durability, a sort of micron-sized air-cells could be generated in aerosol form, by passing out compressed air to dense form generating surfactants. Therefore to circumvent certain drawbacks of conventional LWC, the study delineated to bring out an innovative air-cell impregnated concrete (AIC) material, with homogenous mixing of cement, sand, water and uniformly distributed micron-sized air-cells wherein course-aggregates were replaced with air-cells. This uniform air-cell distribution creates durable concrete with unique feature characteristics since the micron-sized air-cells will be stable and does not collapse. The suitable surfactant towards contributing the strength and durability of proposed AIC structure are assessed, based on results.

Tailoring the Li+ Intercalation Energy of Carbon Nanocage Anodes Via Atomic Al-Doping for High-Performance Lithium-Ion Batteries.

Graphitic carbon materials are widely used in lithium-ion batteries (LIBs) due to their stability and high conductivity. However, graphite anodes have low specific capacity and degrade over time, limiting their application. To meet advanced energy storage needs, high-performance graphitic carbon materials are required. Enhancing the electrochemical performance of carbon materials can be achieved through boron and nitrogen doping and incorporating 3D structures such as carbon nanocages (CNCs). In this study, aluminum (Al) is introduced into CNC lattices via chemical vapor deposition (CVD). The hollow structure of CNCs enables fast electrolyte penetration. Density functional theory (DFT) calculations show that Al doping lowers the intercalation energy of Li+. The Al-boron (B)-nitrogen (N-doped CNC (AlBN-CNC) anode demonstrates an ultrahigh rate capacity (≈300 mAhg-1 at 10 Ag-1) and a prolonged fast-charging lifespan (862.82 mAhg-1 at 5 Ag-1 after 1000 cycles), surpassing the N-doped or BN-doped CNCs. Al doping improves charging kinetics and structural stability. Surprisingly, AlBN-CNCs exhibit increased capacity upon cycling due to enlarged graphitic interlayer spacing. Characterization of graphitic nanostructures confirms that Al doping effectively tailors and enhances their electrochemical properties, providing a new strategy for high-capacity, fast-charging graphitic carbon anode materials for next-generation LIBs.

Experimental and comparative analysis between nitrile rubber foam insulated and vacuum insulated fiber reinforced plastic tank used in a low temperature sensible heat storage system for building space cooling applications

AbstractThermal energy storage devices are gaining importance and momentum in the building space cooling and renewable energy applications. Retaining the stored energy for long hours through proper insulation is crucial in achieving economic benefits. In the present research, a novel composite material (FRP) is introduced for the development of cool storage tank along with two different methods of insulation (nitrile rubber foam insulation and vacuum insulation) to assess the performance of cool energy retention. The results show that the effect of vacuum insulation is lower compared with nitrile rubber foam insulation. This is due to the low specific heat capacity of the FRP material compared with air that increases the surface temperature of the tank than the ambient air during the day time in the case of vacuum insulation. Hence the study concludes that the additional layer of insulation material with high specific heat capacity than the ambient air to be added on the surface to avoid the overheating of the wall surface. The results are useful in designing the insulation for thermal storage tanks and managing the heat loss.

Reviving Sodium Tunnel Oxide Cathodes Based on Structural Modulation and Sodium Compensation Strategy Toward Practical Sodium-Ion Cylindrical Battery.

As a typical tunnel oxide, Na0.44MnO2 features excellent electrochemical performance and outstanding structural stability, making it a promising cathode for sodium-ion batteries (SIBs). However, it suffers from undesirable challenges such as surface residual alkali, multiple voltage plateaus, and low initial charge specific capacity. Herein, an internal and external synergistic modulation strategy is adopted by replacing part of the Mn with Ti to optimize the bulk phase and construct a Ti-containing epitaxial stabilization layer, resulting in reduced surface residual alkali, excellent Na+ transport kinetics and improved water/air stability. Specifically, the Na0.44Mn0.85Ti0.15O2 using water-soluble carboxymethyl cellulose as a binder can realize a capacity retention rate of 94.30% after 1,000 cycles at 2C, and excellent stability is further verified in kilogram large-up applications. In addition, taking advantage of the rich Na content in Prussian blue analog (PBA), PBA-Na0.44Mn1-xTixO2 composites are designed to compensate for the insufficient Na in the tunnel oxide and are matched with hard carbon to achieve the preparation of coin full cell and 18650 cylindrical battery with satisfactory electrochemical performance. This work enables the application of tunnel oxides cathode for SIBs in 18650 cylindrical batteries for the first time and promotes the commercialization of SIBs.

Evaluation of the Polypyrrole Coupling Mode for High-Performance Dual-Ion Batteries.

Due to the advantages of large interstitial sites, antisolubility, and reversible insertion and extraction of anions, polypyrrole (PPy) has become an excellent P-type electrode material for dual-ion batteries. Unfortunately, PPy electrodes inevitably suffer from low specific capacity and poor cycle stability because of structural disintegration during repeated cycling as well as poor doping ability brought on by aggregation or cross-linking within the PPy chain. In this work, PPy with different proportions of coupling mode (α-α, α-β, or β-β coupling) was derived from different preparation methods. Among them, PPy derived from the interfacial frozen polymerization method (I-PPy) is dominated by the α-α coupling mode and possesses the best anion doping ability and the highest specific capacity of 119 mAh g-1 at 100 mA g-1 compared with PPy derived from electrochemical deposition (E-PPy) and chemical oxidation method (C-PPy) (both less than 40 mAh g-1). This work verifies that increasing the proportion of the α-α coupling mode in the PPy electrode is a useful strategy to enhance the anion doping ability and capacity of dual-ion batteries.

Low-crystalline 1T/2H-MoSe2 heterostructure as the high-rate and ultra-long-lifespan cathode materials for magnesium ion batteries

Two-dimensional layered-like materials are attracted extensive attention to be the potential cathode materials for magnesium ion batteries because of the wide layer distances and high capacities. Whereas such strong interaction between bivalent Mg2+ and layered cathode materials is prone to cause the slow diffusion kinetics, and irreversible electrochemical reaction, finally bringing about the low specific capacity and inferior rate capability. Meanwhile, limited by the inherent crystal structure of MoSe2 and unsuitable electrolyte, the magnesium storage properties are not ideal. Herein, the low-crystalline 1T/2H-MoSe2 heterostructure (LC-MoSe2) is synthesized via one-step hydrothermal method. Such low-crystalline feature of LC-MoSe2 and MgCl+ in the electrolyte significantly decrease the Mg2+ diffusion barrier, and largely promote the Mg2+ diffusion kinetics. The rich heterogeneous interfaces in the 1T/2H-MoSe2 boost the electron/ion transfer kinetics and endow plentiful active sites for the Mg2+ storage. As expected, the LC-MoSe2 exhibits a high discharge capacity (257.4 mAh g−1/0.5 A g−1/200 cycles) and stable long-span cyclic life of 2000/1000 loops even at 2/5 A g−1, distinctly transcending those of relatively high-crystalline MoSe2 (HC-MoSe2). Such electrode can also surprisingly cycle at an ultra-high rate of 10 A g−1. Meanwhile, the charge transfer/ion diffusion kinetics along with charge storage mechanism of LC-MoSe2 are carried out by various kinetics strategies from experimental and theoretical aspects. The reaction mechanism has also been discussed by some ex-situ characterization techniques. The remarkable Mg2+ storage properties of LC-MoSe2 cathode materials provide new ideas for the long-run development of MIBs.

A high-capacity and stable dual-ion battery based on an ultra-large lattice-spacing amorphous carbon anode

Compared with traditional lithium-ion batteries (LIBs), dual-ion batteries (DIBs) offer advantages such as high operating voltage, good safety performance, and low cost. However, DIBs often suffer from challenges such as low specific capacity and poor cycling performance in practical applications. Here, a layered nitrogen-doped carbon anode has been prepared using a one-step pyrolysis method with excellent Li+ storage sites. The large lattice spacing of 0.55 nm provides more space for the storage and migration of active ions. Concurrently, the utilization of concentrated electrolyte facilitated the electrochemical window and the restrained solvation of ions, which helps to boost ion transport and improve the stability of the electrolyte and the operating voltage of DIBs. The assembled DIBs exhibit a high specific discharge capacity of 179.27 mA h g−1, within a 2.5–4.8 V voltage range, and excellent cycling stability of 3500 cycles without degradation. Specifically, the structural evolution of the electrodes during charging and discharging and the working mechanism of the DIBs are also explored. The DIBs system designed in this paper provides a facile and scalable approach to promote the development of DIBs with low-cost and high-performance.

Boosting the Efficiency and Stability of Li-CO2 Batteries via a Ruthenium-Based Olefin-Metathesis Catalyst.

The practical application of Li-CO2 batteries is significantly hindered by high charge potential and short lifespan, mainly due to sluggish reaction kinetics and inadequate reaction reversibility. Homogeneous catalysts added to the electrolyte provide a promising strategy to address these issues. In this work, the third-generation Grubbs catalyst (G-III), which is efficient for olefin metathesis reactions, has been adopted as a homogeneous catalyst for Li-CO2 batteries. Batteries with G-III exhibited a low overpotential of 0.86 V and a lifespan of 1300 h at a current density of 300 mA g-1. Even at a high current density of 2000 mA g-1, the batteries remained stable for over 300 cycles, with an initial overpotential of 1.11 V. A two-step discharge/charge reaction involving Li2C2O4 as an intermediate was well illustrated, attributed to both low overpotentials and high specific capacity. These findings provide insights into catalyst selection and mechanism analysis for Li-CO2 batteries, offering practical strategies for Li-CO2 battery performance enhancement and practical applications.

Constructing MXene-/coconut-derived carbon composite as a robust anode material for enhanced lithium storage

MXene is one kind of a promising anode material due to its graphene-like structure, excellent electrochemical characteristics and low lithium ion diffusion barrier. But the lower specific capacity couldn’t meet the demands in practical application. Here, we have constructed coconut-derived carbon anchored within the MXene layers, which improves the conductivity to prompt the kinetics upon redox reactions, in the meantime, shorts the transfer distance and buffers volume changes, synergistically improving the electrochemical reversibility during charge and discharge processes. Naturally, the MXene/C hybrid anode delivers a high initial discharge specific capacity of 1951.7 mAh g[Formula: see text] at 0.1 A g[Formula: see text]. Additionally, it maintains a stable cycle with a reversible capacity of 511.7 mAh g[Formula: see text] after 500 cycles at 0.5 A g[Formula: see text]. This work paves a straightforward avenue to developing a versatile MXene-based anode for high performance LIBs.