Enhanced Rate Capability Research Articles

FeSe2/TiO2 heterostructure as an efficient photocatalyst and their electrochemical energy storage applications

This paper reported the facile synthesis of FeSe2 and TiO2 and their different wt.% composites (75 and 50% of TiO2, here after FT-1 and FT-2) via solvothermal in/ex-situ sol-gel method for the first time efficient photocatalytic degradation of Rhodamine removal and supercapacitor applications. Small bandgap energy was obtained for FT-1 samples from the optical analysis, with a more negligible band edge absorption. The result shows that the composite of FeSe2 and TiO2 increases the absorption, which collectively enhances the separation of the charge carriers and redox activities. The photocatalytic activities analysis demonstrated that the FT-1 sample reveals the fastest removal of the RB dye in just 60 min (FT-2, FeSe2, and TiO2 = 90, 100, and 180 min) with good stability (98%) after several cycles. As supercapacitor electrode materials, all electrodes showed well-defined peaks in their CV loops and voltage plateaus in their charge/discharge profile, illustrating the pseudocapacitive charge storage mechanism. No voltage decay was observed during many discharge currents from the charge/discharge investigation, demonstrating the chosen potential frame is a suitable window for the FeSe2 and TiO2 nanomaterials. The higher capacity of 295 (FT-1) than other electrodes (FeSe2, TiO2, and FT-2 = 220, 115, and 240 C/g) at 1 A/g was obtained to reach 180 at 10 A/g, resulting in an enhanced rate capability of 82%. The high rate capability is the cause of its more minor charge transfer resistance, resulting in higher conductivity and supporting rapid charge transport kinetics. These outstanding properties open a new avenue for other FeSe2 and TiO2 nanomaterials for efficient energy storage technologies.

Scalable Interlayer Nanostructure Design for High-Rate (10C) Submicron Silicon-Film Electrode by Incorporating Silver Nanoparticles

High C-rate capability at 10C is a key performance indicator for the commercialization of the next-generation high-charging lithium microbattery. However, silicon (Si) anode satisfying the prerequisite high specific capacity suffers from poor electron/ionic conductivity, seriously limiting the 10C rate capability. Accordingly, we propose the strategy of inserting highly conductive silver nanoparticles (AgNPs) as an interlayer between two RF-sputtered amorphous Si thin films to form an Si/Ag/Si multilayered anode, with the density and spatial distribution of the AgNPs well-controlled by thermal evaporation. This strategy is exclusively beneficial to scale up film thickness for higher capacity. Without AgNPs, the 10C rate performance of the double-layer Si (D_Si) is worse than the single layer (S_Si) in the same total thickness, suggesting the adverse effect of the interface. However, this situation is progressively improved with the AgNPs density incorporated at the interface, where the densest AgNPs anode (D_SiAg3) demonstrated a noticeable improvement reaching 1250 mAh/g at 10 C with a 46% capacity retention rate. By scaling up to triple layers, T_SiAg3 performed the superior 10C rate capability to T_Si, testifying to the scalable potential of the unique design for boosting high-power batteries. Finally, with electrochemical impedance spectroscopy results, a possible mechanism to explain the enhancement in rate capability is subject to where Li-ion diffusion is accelerated by the charge-induced electric field condensing around the AgNPs. This design for a multilayered nanocomposite can contribute to the design and fabrication of high-charging batteries and battery-on-chip.

Dynamic phase evolution of MoS3 accompanied by organodiselenide mediation enables enhanced performance rechargeable lithium battery

Considerable efforts have been devoted to Li-S batteries, typically the soluble polysulfides shuttling effect. As a typical transition metal sulfide, MoS2 is a magic bullet for addressing the issues of Li-S batteries, drawing increasing attention. In this study, we introduce amorphous MoS3 as analogous sulfur cathode material and elucidate the dynamic phase evolution in the electrochemical reaction. The metallic 1T phase incorporated 2H phase MoS2 with sulfur vacancies (SVs-1T/2H-MoS2) decomposed from amorphous MoS3 achieves refined mixing with the "newborn" sulfur at the molecular level and supplies continuous conduction pathways and controllable physical confinement. Meanwhile, the insitu-generated SVs-1T/2H-MoS2 allows lithium intercalation in advance at high discharge voltage (≥1.8 V) and enables fast electron transfer. Moreover, aiming at the unbonded sulfur, diphenyl diselenide (PDSe), as a model redox mediator is applied, which can covalently bond sulfur atoms to form conversion-type organoselenosulfides, changing the original redox pathway of "newborn" sulfur in MoS3, and suppressing the polysulfides shuttling effect. It also significantly lowers the activation energy and thus accelerates the sulfur reduction kinetics. Thus, the insitu-formed intercalation-conversion hybrid electrode of SVs-1T/2H-MoS2 and organoselenosulfides realizes enhanced rate capability and superior cycling stability. This work provides a novel concept for designing high-energy-density electrode materials.

LiNO3-Assisted Succinonitrile-Based Solid-State Electrolyte for Long Cycle Life toward a Li-Metal Anode via an In Situ Thermal Polymerization Method.

Succinonitrile (SN)-based electrolytes have a great potential for the practical application of all-solid-state lithium-metal batteries (ASSLMBs) due to their high room-temperature ionic conductivity, broad electrochemical window, and favorable thermal stability. Nevertheless, the poor mechanical strength and low stability toward Li metal hinder the further application of SN-based electrolytes to ASSLMBs. In this work, the LiNO3-assisted SN-based electrolytes are synthesized via an in situ thermal polymerization method. With this method, the mechanical problem is negligible, and the stability of the electrolyte enhances tremendously toward Li metal due to the addition of LiNO3. The LiNO3-assisted electrolytes exhibit a high ionic conductivity of 1.4 mS cm-1 at 25 °C, a wide electrochemical window (0-4.5 V vs Li+/Li), and excellent interfacial compatibility with Li (stable for over 2000 h at a current density of 0.1 mA cm-1). The LiFePO4/Li cells with the LiNO3-assisted electrolytes present significantly enhanced rate capability and cycling performance compared to the control group. NCM622/Li batteries also exhibit good cycling and rate performances with a voltage range of 3.0 to 4.4 V. Furthermore, ex situ SEM and XPS are employed. A compact interface is observed on Li anode after cycling, and the polymerization of SN is found to be suppressed. This paper will promote the development of practical application of SN-based ASSLMBs.

Electrode Separators for the Next-Generation Alkaline Water Electrolyzers.

Multi-gigawatt-scale hydrogen production by water electrolysis is central in the green transition when it comes to storage of energy and forming the basis for sustainable fuels and materials. Alkaline water electrolysis plays a key role in this context, as the scale of implementation is not limited by the availability of scarce and expensive raw materials. Even though it is a mature technology, the new technological context of the renewable energy system demands more from the systems in terms of higher energy efficiency, enhanced rate capability, as well as dynamic, part-load, and differential pressure operation capability. New electrode separators that can support high currents at small ohmic losses, while effectively suppressing gas crossover, are essential to achieving this. This Focus Review compares the three main development paths that are currently being pursued in the field with the aim to identify the advantages and drawbacks of the different approaches in order to illuminate rational ways forward.

Superior stability and electrochemical performance of Li2ZnTi3O8 anode enabled by the derivatives from the isomers of trithiocyanuric acid

Rechargeable Li-ion batteries with fast-charging performance, long cycle life and safety are desirable. Herein, an efficient hydrothermal avenue was adopted to modify Li2ZnTi3O8 (LZTO) with trithiocyanuric acid (TCA). The two isomers of keto and enol TCA undergo different evolutions in the hydrothermal and electrochemical processes. For the enol TCA in the hydrothermal process, the HS– bonds close to LZTO react with LZTO to introduce superficial S-doping to facilitate electron conductance, and the others oxidize into –SO3– groups which transform into –SO3Li groups in lithiation process to favor Li+ migration. The keto TCA is stable in the hydrothermal process, yet the CS groups oxidize into –SO3– groups in anodic process and yield –SO3Li groups in subsequent cathodic process for Li+ diffusion. Despite these changes, the six-membered cyclic structures in both the keto and enol TCA are stable and coordinate with LZTO to create coating layer. The organic coating with good mechanical performance and strong interaction with PVDF protects LZTO from electrolyte corrosion and side reactions. Therefore, the TCA-modified LZTO demonstrates accelerated Li-ion migration and electron transfer, significantly enhanced rate capability and cycling stability.

Optimized Fabrication of Bimetallic ZnCo Metal-Organic Framework at NiCo-Layered Double Hydroxides for Multiple Storage and Capability Synergy All-Solid-State Supercapacitors.

Rational design and structural regulation of hybrid nanomaterials with superior electrochemical performance are crucial for developing sustainable energy storage platforms. Among these materials, NiCo-layered double hydroxides (NiCo-LDHs) demonstrate an exceptional charge storage capabilities owing to their tunable 2D lamellar structure, large interlayer spacing, and rich redox electrochemically active sites. However, NiCo-LDHs still suffer from sever agglomeration of their particles with limited charge transfer rates, resulting in an inadequate rate capability. In this study, bimetallic ZnCo-metal organic framework (MOF) tripods were grown on the surface of NiCo-LDH nanowires, which significantly reduced the self-agglomeration and stacking of the NiCo-LDH nanowire arrays, offering more accessible active sites for charge transfer and shortening the path for ion diffusion. The fabricated hybrid ZnCo-MOF@NiCo-LDH and its individual counterparts were tested as supercapacitor electrodes. The ZnCo-MOF@NiCo-LDH electrode demonstrated a remarkable specific capacitance of 1611 F g-1 at 2 A g-1 with an enhanced rate capability of 66% from 2 to 20 A g-1. Moreover, an asymmetric all solid-state supercapacitor device was constructed using ZnCo-MOF@NiCo-LDH and palm tree-derived activated carbon (P-AC) as positive and negative poles, respectively. The constructed device can store a high specific energy of 44.5 Wh Kg-1 and deliver a specific power of 876.7 W Kg-1 with outstanding Columbic efficiency over 10,000 charging/discharging cycles at 15 A g-1.

Enhanced rate capability and cycling stability of conductive oxide-coated LiNi0.8Co0.1Mn0.1O2 for lithium-ion batteries

Enhanced rate capability and cycling stability of conductive oxide-coated LiNi0.8Co0.1Mn0.1O2 for lithium-ion batteries

Synergy between highly dispersed Ni nanocrystals and graphitized carbon derived from a single source as a strategy for high performance Lithium-Sulfur batteries

Due to their higher energy density, lower prices, and more environmentally friendly active components, Li-S batteries will soon compete with the current Li-ion batteries. However, issues persist that hinder this implementation, such as the poor conductivity of S and sluggish kinetics due to the polysulfide shuttle, among others. Herein, Ni nanocrystals encapsulated in a C matrix are obtained by a novel strategy based on the thermal decomposition of a Ni oleate-oleic acid complex at low-to-moderate temperatures: 500 and 700 °C. The two C/Ni composites were employed as hosts in Li-S batteries. Although the C matrix is amorphous at 500 °C, it is highly graphitized at 700 °C. At this moderate temperature, the simultaneous generation of Ni nanocrystals and the carbon matrix enhances the catalytic activity of Ni toward the graphitization process, which is negligible if starting from a mixture of a Ni salt and carbon source, even when calcined at temperatures as high as 1000 °C. The electrode made from the C/Ni composite obtained at 700 °C exhibits a high reversible capacity and an enhanced rate capability, much better not only than the C/Ni composite obtained at 500 °C but than others based on amorphous C calcined at very high temperatures, around 1000 °C. These properties are attributed to an increase in the electrical conductivity parallel to the ordering of the layers. We believe this work provides a new strategy to design C-based composites capable of combining the formation of nanocrystalline phases and the control of the C structure with superior electrochemical properties for Li-S batteries.

A Theory‐Driven Complementary Interface Effect for Fast‐Kinetics and Ultrastable Zn Metal Anodes in Aqueous/Solid Electrolytes

AbstractThe undesirable side reactions and uncontrolled deposition leads to the electrochemical failure of Zn metal anodes. Herein, driven by theory calculations, a surface texture engineering and passivation layer protection dual‐interface strategy is developed. Benefiting from the complementary interface effect, such a dual‐interface can realize the integrated regulation of interfacial transport and deposition. That is, inhibiting water‐induced side reactions, accelerating the de‐solvation of hydrated zinc ions, homogenizing the ion flux, and guiding the Zn(002)‐preferred orientation deposition. As a result, such a dual‐interface modulated Zn electrode enables a significantly extended stability and a smaller nucleation barrier and polarization effect. Unexpectedly, it can steadily operate for 6600 h at 0.5 mA cm−2 and 0.5 mA h cm−2, corresponding to a lifespan >9 months. Highly reversible Zn plating and stripping can be still retained when the current density is improved up to 1, 5, 10, and even 20 mA cm−2. Beyond that, when it is applied to Zn metal batteries, enhanced rate capability, and cyclic stability can be realized in both aqueous Zn/MnO2 batteries and solid‐state Zn/VO2 batteries. This design concept of complementary interface effect is expected to provide a new insight into high reversibility Zn metal anodes.

Synthesis of LaW/Ag/GNRs nanocomposite: Application as transducer material for the simultaneous nano molar detection of synthetic dyes and as anode material for Li ion batteries

In this present research, we have synthesized the lanthanum tungstate/silver nanoparticle/graphene nanoribbons (LaW/Ag/GNRs) nanocomposite as a novel system for the simultaneous electrochemical determination of two synthetic food colorants sunset yellow (SY) and acid yellow (AY). The synthesised nanocomposite modified graphite electrode (Gr) provides the presence of more active sites for the transfer of electrons, allowing for a stronger voltametric response that is due to the faster rate of electron transfer from the analytes. The as-synthesized nanocomposite was characterized by different analytical methods. The enhanced anodic peak currents represented the excellent analytical performance for simultaneous detection of SY and AY in the range of 20 nm to 450 nM, with a low limit of detection (LOD) of 0.025 nm for SY and 0.050 nM for AY. This proposed sensor showed excellent recovery values real sample analysis. Further the nanocomposite was used as the anode material in Li ion batteries and was evaluated in an aqueous saturated Li2SO4 electrolyte. In terms of cycle performance, enhanced rate capability, and high discharge capacity, LaW/Ag/GNRs nanocomposite has made significant advancements. The lithiated LaW/Ag/GNRs nanocomposite half-cell vs. SCE offers a 227.86 mA h g−1 capacity up to 10 cycles at 0.08 mA. In the potential range of 1.0 to 0.0 V, the whole cell configuration LaW/AgNPs/GNRs|aq.saturated Li2SO4|LiMn2O4 produced a discharge capacity of 240.24 mA h g−1. With 96.95% columbic efficiency, the battery performance of the cell has greatly boosted. This excellent result clearly fits this material as an anode in future aqueous rechargeable lithium batteries for energy technology.

Silk fibroin-based biopolymer composite binders with gradient binding energy and strong adhesion force for high-performance micro-sized silicon anodes

Micro-sized silicon anodes have shown much promise in large-scale industrial production of high-energy lithium batteries. However, large volume change (>300%) of silicon anodes causes severe particle pulverization and the formation of unstable solid electrolyte interphases during cycling, leading to rapid capacity decay and short cycle life of lithium-ion batteries. When addressing such issues, binder plays key roles in obtaining good structural integrity of silicon anodes. Herein, we report a biopolymer composite binder composed of rigid poly(acrylic acid) (PAA) and flexible silk fibroin (SF) tailored for micro-sized silicon anodes. The PAA/SF binder shows robust gradient binding energy via chemical interactions between carboxyl and amide groups, which can effectively accommodate large volume change of silicon. This PAA/SF binder also shows muchstronger adhesion force and improved binding towards high-surface/defective carbon additives, resulting in better electrochemical stability and higher coulombic efficiency, than conventional PAA binder. As such, micro-sized silicon/carbon anodes fabricated with novel PAA/SF binder exhibit much better cyclability (up to 500 cycles at 0.5 C) and enhanced rate capability compared with conventional PAA-based anodes. This work provides new insights into the design of functional binders for high-capacity electrodes suffering from large volume change for the development of next-generation lithium batteries.

New insights into high-rate and super-stable aqueous zinc-ion batteries via the design concept of voltage and solvation environment coordinated control

As the great potential host materials, the application of low-valent vanadium-based compounds for aqueous zinc-ion batteries are usually suffered from the insufficient storage capability and cycle performance. In this work, a unique voltage and solvation environment coordinated control strategy was developed to unlock the MXene derived VNxOy/C heterostructure as robust host applied for aqueous zinc-ion batteries. As the results indicated, such VNxOy/C can be completely converted to the new phase of Zn3(OH)2V2O7·2H2O when the cut-off voltage was controlled at 0.2–2.0 V. Moreover, unlike the mechanism of H+/Zn2+ co-insertion/extraction accompanied with the by-product formation in the electrolyte of pure H2O system, it was demonstrated that the introduction of hydrophilic polyethylene glycol (PEG) into electrolyte enables tailoring the solvation environment, forming the proton shielding to eliminate the blocking effect of by-products on interfacial transport kinetics and storage reversibility of the electrode, thus realizing controllable Zn2+-dominant insertion/extraction mechanism. Unexpectedly, such low-valent VNxOy/C electrode under the coordinated control of voltage and solvation environment enables achieving a significantly enhanced rate capability and ultralong cycle lifespan, which can retain the specific capacities of 369.4 and 112.7 mAh g−1 after 2000 cycles at 0.5 A g−1 and 14,200 cycles at 10 A g−1, respectively. Such novel and efficient avenue for the development of low-valent cathode material is expected to deepen the understanding of the construction of efficient energy storage systems including but not limited to aqueous zinc-ion batteries.

Enhanced rate capability of S@Co3O4 microsphere wrapped by rGO for cathodes of lithium-sulfur batteries

S@Co3O4/rGO (SCG) composite was synthesized via a readily solvothermal method and subsequent thermal treatment for cathodes of lithium-sulfur (Li-S) batteries, in which Co3O4 hollow microsphere used as a sulfur host has been initially wrapped by conductive reduced graphene oxide (rGO) network. Benefited from polar Co-S bond forming strong adsorption with polysulfides and hollow structure providing void spaces for volumetric expansion, Co3O4 additive effectively alleviates such issues as shuttle effect and electrode pulverization/failure. Moreover, rGO layer covering onto surface of Co3O4 microsphere further increases electrical conductivity and structural stability of electrode. As a result, SCG composite exhibits superior electrochemical performances with a high specific capacity of 1131.6 mAh g−1 at 0.2 C, and an enhanced rate capability tolerating a high current density of up to 5 C. The design strategy on composition and structure of cathode in this work will provide a novel route for achieving high-energy Li-S batteries.

Tri-functionalized Li2B4O7 coated LiNi0.5Co0.2Mn0.3O2 for boosted performance lithium-ion batteries

Building stable interfacial structure is regarded as an effective strategy to enhance structure stability and facilitate Li+ migration. Herein, LiNi0.5Co0.2Mn0.3O2 (NCM523) cathode materials are surface-modified with amorphous Li2B4O7 (LBO) Li+-conductor with high relative permittivity. Comparing to pristine NCM, surface-modified electrodes exhibit a significant improvement in capacity retention and rate capability, delivering a reversible capacity of 163.4 mAh·g−1 and 87.6 % capacity retention over 100 cycles at 1 C. Besides the protection from HF-attack, enlarged crystal lattice volume by boron-doping and Li+-conductor characteristic of Li2B4O7 is beneficial for Li+-ion diffusion in NCM523 and reduces charge transfer resistance. In addition, the reduced work function induced by Li2B4O7-coating is helpful for the suppression of the electrolyte oxidation, the enhanced rate capability and improved cyclic stability in terms of interfacial stability. Moreover, dielectric polarization field induced by high-permittivity Li2B4O7 at NCM523-Li2B4O7-electrolyte triple-phase interface would synergistically facilitate Li-ion migration across electric double-layer. Our work would provide a new insight into the enhanced performance of cathode material surface-modified by Li+-conductor with large relative permittivity.

Zeolites as multifunctional additives stabilize high-voltage Li-batteries based on LiNi0.5Mn1.5O4 cathodes, mechanistic studies

The work reported herein discusses the improved electrochemical and thermal behavior of LiNi0.5Mn1.5O4 (LNMO) spinel cathodes via surface engineering using a series of zeolites. The limiting issues of these high voltage electrodes are phase transition during Li-ions intercalation/de-intercalation processes, weakening the active material's structure. Besides, it initiates harmful interfacial side reactions, including solution species oxidation and Ni & Mn dissolution, affecting their long-term cycling stability severely and detrimentally. Therefore, we propose a zeolite-based surface modification of LNMO involving a simple surface coating strategy that includes liquid-phase (ethanol) mixing followed by heat treatment at 200 °C under nitrogen gas flow. The cathodes comprising LNMO coated with 2 wt% zeolites exhibited significantly improved cycling stability than the reference cathodes with the uncoated material. Furthermore, we discovered that the zeolite species adsorbed to the LNMO surface act as buffer interphase that enhance the electrodes' redox kinetics, trapping dissolved-TMs ions and serving as local Li+-ions reservoirs. Pouch cells containing graphite anodes and zeolite-coated LNMO cathodes demonstrated impressively improved electrochemical behavior in capacity retention during prolonged cycling, enhanced rate capability, lower voltage hysteresis, and direct current internal resistance (DCIR) evolution. The zeolite-based surface coating participates in (i) lowering HF formation in battery solutions by absorbing trace water, (ii) HF scavenging, and (iii) lowering TMs cations dissolution. Furthermore, Si and Al constituents of the zeolites can deposit on Li-anodes and possibly increase their stability, later established by additional electrochemical studies of full-pouch cells comprising uncoated LNMO cathodes vs. zeolite-coated graphite anodes. Other pivotal findings of this work are the coherent structural, morphological, and thermal stabilization of zeolite-coated LNMO cathodes during prolonged cycling experiments.

Structured aqueous processed lignin-based NMC cathodes for energy-dense LIBs with improved rate capability

The cost and environmental impact of Li-ion batteries can be reduced through aqueous processing of cathode materials. Here, we used aqueous processing to prepare lignin-based NMC111 cathodes for Li-ion batteries with enhanced rate capability.

Turning Berlin green frameworks into cubic crystals for cathodes with high-rate capability

One-pot synthesized Berlin green cubes exhibit enhanced rate capability and cycle life when employed as a lithium-ion battery cathode.

S/N-co-doped graphite nanosheets exfoliated via three-roll milling for high-performance sodium/potassium ion batteries

Due to its larger ionic radius, further studies are needed before graphite can be used as an anode for sodium/potassium-ion batteries (SIBs/KIBs). It is believed that doping and increasing the layer spacing can improve the Na+/K+ storage. Herein, S/N co-doped graphite nanosheets (GNS) with an enlarged interlayer spacing of 0.39 nm were prepared via exfoliation with three-roll milling (TRM) combined with thiourea heated at different temperatures. This method generates abundant defects and active sites for GNS, as well as facilitates rapid access and transport of electrolytes and electrons/ions. The electrochemical results show that the S/N-doped GNS exfoliated 15 times and heated at 600 °C (SNGNS15-600) with thiourea as the electrode delivers a discharge capacity of 94 mAh g–1 over 6000 cycles at 10 A g–1 with an enhanced rate capability and stable performance for application in SIBs. Calculations using density functional theory show that the increased interlayer spacing by TRM and S, N co-doping enhances the adsorption energies of Na+ on graphite, thus improving the Na+ storage. As the anode for KIBs, the SNGNS15-600 electrode has a capacity of 142 mAh g–1 after 5000 cycles at 0.5 A g–1. This study provides an essential theoretical basis for the effective exfoliation of layered graphite-based materials and their applications in energy storage.

Cauliflower-like nanostructured ZnV2S4 as a potential cathode material to boost-up high capacity and durability of the aqueous zinc-ion battery

Owing to their unique design and development, high safety and low-cost efficient cathode is still at the forefront of research for rechargeable zinc-ion batteries. However, the suitable cathode operating with ultrahigh capacity with a dendrite-free anode reaction mechanism remains challenging. In this, the first archetype of a high-rate and morphologically stabled cathode material is constructed from novel cauliflower-like nano-ZnV2S4 for aqueous zinc-ion batteries. Thus, nano-ZnV2S4 was prepared with an anion exchange reaction using ZnV2(OH)8 cauliflower-like nanostructured array as a template interestingly no morphological and shape changes were detected. The as-prepared nano-ZnV2S4 electrode reveals a specific discharge capacity of 348.2 mAh/g during 0.5 A/g with enhanced rate capability and excellent capacity retention of 89.2% at 4 A/g current density even after completing 1000 cycles.