Fast Electrochemical Reaction Research Articles

Vacancy engineering and hydrophilic construction of CoFe-MOF for boosting water splitting by in situ phytic acid treatment

Deliberate engineering of the structures and components of Metal–organic frameworks (MOFs) can provide unlimited potential for developing efficient electrocatalysts for water splitting. Herein, we develop a green strategy to synthesize CoFe–MOF@Pa via a simple and controllable phytic acid (Pa) etching technique. The Pa etching strategy can break the M−O in CoFe–MOF to create vacancies and introduce hydrophilic groups on the surface of CoFe–MOF to enhance the hydrophilicity. The obtained porous CoFe–MOF@Pa with vacancies not only creates more active sites and facilitates charge redistribution, but also the improved hydrophilicity promotes the adequate contact of electrolytes with active sites, thereby enhancing the fast electrochemical reactions. As a result, the CoFe–MOF@Pa shows excellent OER performance (203 mV at 10 mA cm−2) and low Tafel slope (57.1 mV dec-1). Furthermore, CoFe–MOF@Pa&CoFe–MOF@Pa for water splitting, it only requires a cell voltage of 1.66 V without iR compensation at 10 mA cm−2. More importantly, CoFe–MOF@Pa also shows long-term activity and stability compared to pristine CoFe–MOF. This feasible strategy in this study is expected to provide insights into the preparation of efficient and robust electrocatalysts for water splitting.

Advanced Fiber-Shaped Aqueous Zn Ion Battery Integrated with Strain Sensor.

Multifunctional batteries have attracted increasing attention, offering additional functionalities beyond the conventional batteries. Herein, we report a fiber-shaped Zn ion battery that not only acts as a high-performance power supply but also provides a sensing function to monitor human motions. Titanium fiber coated with α-MnO2 nanoflowers is exploited as the cathode for the fiber-shaped Zn ion battery, taking full advantage of such unique three-dimensional nanoflower structures of α-MnO2 with a large electrochemically active surface area and fast electrochemical reaction kinetics. Thus, the obtained fiber-shaped Zn ion battery shows a high capacity of 280 mAh g-1 at 0.1 A g-1, resulting in a notable energy density of 396 Wh kg-1, good stability (capacity retention of 80.6% after 300 cycles), and high flexibility. As a demonstration, an electronic watch and five LEDs are successfully driven by two fiber-shaped Zn ion batteries. Furthermore, the fiber-shaped Zn ion battery is integrated with a strain sensor based on a carbon nanotube/polydimethylsiloxane film, offering good sensitivity to monitor motions of different body parts, such as the wrist, finger, elbow, and knee. This work provides insights into multifunctional battery applications for next-generation wearable electronics.

Theoretical Progress of 2D Six-Membered-Ring Inorganic Materials as Anodes for Non-Lithium-Ion Batteries.

The use and storage of renewable and clean energy has become an important trend due to resource depletion, environmental pollution, and the rising price of refined fossil fuels. Confined by the limited resource and uneven distribution of lithium, non-lithium-ion batteries have become a new focus for energy storage. The six-membered-ring (SMR) is a common structural unit for numerous material systems. 2DSMR inorganic materials have unique advantages in the field of non-lithium energy storage, such as fast electrochemical reactions, abundant active sites and adjustable band gap. First-principles calculations based on density functional theory (DFT) can provide a basic understanding of materials at the atomic-level and establish the relationship between SMR structural units and electrochemical energy storage. In this review, the theoretical progress of 2D SMR inorganic materials in the field of non-lithium-ion batteries in recent years is discussed to summarize the common relationship among 2D SMR non-lithium energy storage anodes. Finally, the existing challenges are analyzed and potential solutions are proposed.

Two-dimensional montmorillonite-based heterostructure for high-rate and long-life lithium-sulfur batteries

In lithium-sulfur batteries, the polysulfide redox reaction kinetics is obstructed by unfavorable electron conduction and ion transportation. To address this issue, a two-dimensional (2D) heterostructure with fast ion/electron transport bi-pathways is designed herein by well integrating monolayer lithium-montmorillonite (MMT) and nitrogen-doped reduced graphene oxide (RGO). The low diffusion barrier on the Li-MMT contributes to the fast lithium ion transport, and the nearby RGO builds high electron conduction network, which enables high-efficiency adsorption-diffusion-conversion for polysulfides and achieves fast electrochemical reaction kinetics. Consequently, the lithium-sulfur batteries using the heterostructure interlayer show effective suppression towards the notorious “shuttle effect” of polysulfides, as well as deliver high initial specific capacity of 1317 mAh g−1 at 0.2 C, high rate capability of 848 mAh g−1 even at 3 C, and low capacity decay rate of 0.011% per cycle at 1 C over 200 cycles and 0.067% per cycle at 2 C over 600 cycles. The corresponding pouch cell shows high initial discharge capacity of 1542 mAh g−1 at 0.05 C. This work exhibits the potential application of the low-cost and environmentally-friendly clay as the 2D heterostructure interlayer material for realizing high-energy-density, long-lasting, and high-rate Li-S batteries.

Accordion Frameworks Enable Free‐Standing, High Si Content Anode for Li‐ion Batteries

Implementing high‐performance silicon (Si) anode in actual processing and application is highly desirable for next‐generation, high‐energy Li‐ion batteries. However, high content of inactive matrix (including conductive agent and binder) is often indispensable in order to ensure local conductivity and suppress pulverization tendency of Si particles, which thus cause great capacity loss based on the mass of whole electrode. Here, we designed an accordion‐structured, high‐performance electrode with high Si content up to 95%. Si nanoparticles were well anchored into the interlayer spacings of accordion‐like graphene arrays, and free‐standing electrode was prepared via a simple filtration process without any binder. Conductive accordion framework ensures strong confinement effect of Si nanoparticles and also provides direct, non‐tortuous channels for fast electrochemical reaction kinetics. As a consequence, the accordion Si electrodes exhibit ultrahigh, electrode‐based capacities up to 3149 mAh g−1 (under Si content of 91%), as well as long‐term stability. Also, the accordion electrode can bear extreme condition of over‐lithiation and maintains stable in full‐cell test. This design provides a significant stride in high Si content toward realistic, high‐performance electrodes.

Diamond Supercapacitors: Towards Durable, Safe, and Biocompatible Aqueous-Based Energy Storage.

Durable and safe energy storage is required for the next generation of miniature bioelectronic devices, in which aqueous electrolytes are preferred due to the advantages in safety, low cost, and high conductivity. While rechargeable aqueous batteries are among the primary choices with relatively low power requirements, their lifetime is generally limited to a few thousand charging/discharging cycles as the electrode material can degrade due to electrochemical reactions. Electrical double layer capacitors (EDLCs) possess increased cycling stability and power density, although with as-yet lower energy density, due to quick electrical adsorption and desorption of ions without involving chemical reactions. However, in aqueous solution, chemical reactions which cause electrode degradation and produce hazardous species can occur when the voltage is increased beyond its operation window to improve the energy density. Diamond is a durable and biocompatible electrode material for supercapacitors, while at the same time provides a larger voltage window in biological environments. For applications requiring higher energy density, diamond-based pseudocapacitors (PCs) have also been developed, which combine EDLCs with fast electrochemical reactions. Here we inspect the properties of diamond-related materials and discuss their advantages and disadvantages when used as EDLC and PC materials. We argue that further optimization of the diamond surface chemistry and morphology, guided by computational modelling of the interface, can lead to supercapacitors with enhanced performance. We envisage that such diamond-based supercapacitors could be used in a wide range of applications and in particular those requiring high performance in biomedical applications.

Fabrication of three-dimensional nanocomposite with open cage fullerene polymer and MoS2 for enhanced electrochemical hydrogen evolution activity

Development of advanced materials for electrocatalytic water splitting to generate hydrogen is the key in utilization of renewable energy. In the present work, we constructed three-dimensional (3D) nanoparticles (P-PC60@MoS2) based on an open-cage fullerene polymer (P-PC60), on the surface of which two-dimensional (2D) molybdenum disulfide (MoS2) are grafted vertically. The rational design endows the nanocomposite materials with combined advantages of open-cage fullerenes and MoS2. Especially, compared with traditional fullerenes, polymeric fullerene derivatives are expected to have remarkable electronic, optical, or catalytic properties due to the formation of an interconnected continuous network. The results indicate that the few-layer MoS2 slices arranged vertically on the surface of the fullerene, showing an expanded layer spacing of 6.4 Å, which is beneficial for maximally exposing active edge sites. The hybrid P-PC60@MoS2 with proper synthetic engineering possesses superior catalytic kinetics with surpassing overpotential of 59 mV, Tafel slope of 37 mV dec−1, which are much lower than those of pure MoS2 and P-PC60. The small values indicate fast electrochemical hydrogen evolution reaction (HER) kinetics.

Nanoparticle-modified coatings by electrophoretic deposition for corrosion protection of magnesium

ABSTRACT Magnesium (Mg) and its biocompatible alloys are used as biodegradable materials for temporary implant applications. However, the fast electrochemical reactions in the physiological environment can lead to premature implant failure and damage the surrounding tissues. Here, we report on nanoparticle-modified biopolymer composite coatings processed using alternating current electrophoretic deposition (AC-EPD) to control the corrosion process of Mg–Al alloys. Chitosan–gelatin coatings incorporating bioactive glass particles as reinforcement were supplemented with ZnO and CeO2 nanoparticles and the corrosion resistance was evaluated. CeO2 nanoparticle-modified coatings obtained using AC signals superimposed with a direct current field appeared compact and homogeneous. ZnO nanoparticle-modified coatings had a low surface coverage with significant defects. As a result, CeO2-supplemented coatings processed for as little as 4 min effectively reduced the corrosion current density (i corr) of Mg–Al in Ringer’s solution, whereas ZnO-supplemented coatings did not. CeO2 nanoparticle-modified biopolymer coatings hold potential for fine-tuning the degradation of Mg implants.

Co[sbnd]Fe hydroxyoxalate nanosheets chemically bonded with reduced graphene oxide as High-performance anode for lithium-ion batteries

Transition metal layered double hydroxide (LDHs) materials are promising anodes for high-energy lithium-ion batteries (LIBs) due to their high specific capacities. However, the conductivity and the influence of intercalated anions are key issues for improving their electrochemical performances. Herein, a C2O42− intercalated CoFe-LDH nanosheets anchored on reduced graphene oxide (Co0.83Fe0.17(OH)2(C2O4)0.085·0.08H2O/rGO, CFO) composite was successfully synthesized for the first time by a two-step hydrothermal process. Graphene provides abundant nucleation sites for CoFe-LDH and forms the interconnected porous network skeleton. The intercalated C2O42− ions widen the interlayer spacing of CoFe-LDH to 0.92 nm, which can enhance the transportation of lithium ions. The lithium storage mechanism was proved that the CFO was transformed into a heterostructure nanocomposite (metal hydroxide and lithium oxalate) after discharge, and the high-valent carbon in lithium oxalate was electrocatalytically converted into low-valent carbon. This results in fast electrochemical reactions and high capacity. What’s more, the CFO shows a high reversible capacity (1603 mAh g−1 after 120 cycles), and long-term cycle stability under high current density (CFO delivers a reversible capacity of 860 mAh·g−1 after 1000 cycles at 4 A·g−1). This work provides a new anodes material for application in high-energy LIBs.

Block Copolymer‐Derived Porous Carbon Fibers Enable High MnO2 Loading and Fast Charging in Aqueous Zinc‐Ion Battery

AbstractRechargeable aqueous Zn−MnO2 batteries are promising for stationary energy storage because of their high energy density, safety, environmental benignity, and low cost. Conventional gravel MnO2 cathodes have low electrical conductivity, slow ion (de‐)insertion, and poor cycle stability, resulting in poor recharging performance and severe capacity fading. To improve the rechargeability of MnO2, strategies have been devised such as depositing micrometer‐thick MnO2 on carbon cloth and blending nanostructured MnO2 with additives and binders. The low electrical conductivity of binders and sluggish ion (de‐)insertion in micrometer‐thick MnO2, however, still limit the fast‐charging performance. Herein, we have prepared porous carbon fiber (PCF) supported MnO2 cathodes (PCF@MnO2), comprised of nanometer‐thick MnO2 uniformly deposited on electrospun block copolymer‐derived PCF that have abundant uniform mesopores. The high electrical conductivity of PCF, fast electrochemical reactions in nanometer‐thick MnO2, and fast ion transport through porous nonwoven fibers contribute to a high rate capability at high loadings. PCF@MnO2, at a MnO2 loading of 59.1 wt %, achieves a MnO2‐based specific capacity of 326 and 184 mAh g−1 at a current density of 0.1 and 1.0 A g−1, respectively. Our approach of block copolymer‐based PCF as a support for zinc‐ion cathode inspires future designs of fast‐charging electrodes with other active materials.

Mussel-inspired polydopamine-assisted uniform coating of Li+ conductive LiAlO2 on nickel-rich LiNi0.8Co0.1Mn0.1O2 for high-performance Li-ion batteries

A Li+ conductive LiAlO2 coating layer was uniformly covered on the surfaces of a nickel-rich LiNi0.8Co0.1Mn0.1O2 cathode material through a mussel-inspired, adhesive polydopamine-assisted approach. The adhesive and uniform PDA pre-coating on the Ni0.8Co0.1Mn0.1(OH)2 microspherical surfaces could act as a superior mediator to conformally concentrate the Al3+ precursor on the microsphere surfaces through chemical complexation, thus resulting in a uniform LiAlO2 coating on the LiNi0.8Co0.1Mn0.1O2 microspherical surfaces. The PDA-assisted uniform coating layer of Li+ conductive LiAlO2 could offer multifunctional effects, including effective prohibition of side-reactions between the LiNi0.8Co0.1Mn0.1O2 and electrolyte, significant suppression of the Li/Ni mixing in the LiNi0.8Co0.1Mn0.1O2 crystal lattices, and high Li-ion conductivity for fast electrochemical reactions. Therefore, the PDA-assisted LiAlO2 coated LiNi0.8Co0.1Mn0.1O2 cathode material ([email protected]) presents outstanding cycling stability and rate performance with high discharge capacity of 209 mAh/g at the 1st cycle at the current rate of 0.2 C, 178 mAh/g at the 100th cycle at the current rate of 0.2 C, 138 mAh/g at the 200th cycle at the current rate of 2 C, and 114 mAh/g at the 200th cycle at the current rate of 5 C. These encouraging results demonstrate that the mussel-inspired, adhesive PDA-assisted uniform coating of Li+ conductive LiAlO2 is a promising strategy to achieve high performance of nickel-rich layered oxide cathode material for advanced Li-ion secondary batteries.

Fingerprint-like NiCoP electrode material with rapid charging/discharging performance under large current density

Supercapacitance electrode materials with rapid charging/discharging performance are considerably useful in practical applications for time saving. However, the supercapacitance performance of the electrode materials is sharply degraded with the increase in current density. To achieve fast energy storage for portable devices, bimetallic nickel cobalt phosphides (NiCoPs), composed of special fingerprint-like nanosheets (NSs), are developed as electrode materials, which exhibit a high specific supercapacitance under large charging/discharging current density. The NiCoP NSs are assembled using entangled nanowires with a wide pore size distribution through hydrothermal and phosphorization reactions. The influence of phosphorization temperature on the morphologies, chemical compositions, and supercapacitance performance of NiCoP compounds is investigated. Electrochemical tests show that the fingerprint-like NiCoP NSs deliver a high specific capacitance of 2360, 1900, and 900 F g−1 at 1, 20, and 50 A g−1, respectively, indicating outstanding capacity retentions of 81% (1–20 A g−1) and 38% (1–50 A g−1) at large charging/discharging current density. The assembled asymmetric supercapacitor of NiCoP//activate carbon presents an energy density of 156 Wh kg−1 at 1331 W kg−1 and maintains 67.5 Wh kg−1 at 27000 W kg−1 in aqueous KOH electrolyte. The bimetallic NiCoPs with a tunable fingerprint-like structure can enhance conductivity, provide nanoporous channels, and facilitate fast electrochemical reactions, which are remarkably beneficial for rapid energy storage and conversion applications.

Interface engineering of hierarchical NiCoP/NiCoSx heterostructure arrays for efficient alkaline hydrogen evolution at large current density.

The development of non-noble metal electrocatalysts with high activity and long-term stability for the hydrogen evolution reaction (HER), especially at large current density, is of great significance for industrial hydrogen production from water using renewable electricity. Constructing heterostructures with interfacial interactions is an effective strategy to improve the catalytic performance for large-current-density HER. Herein, we innovatively present a facile two-step electrodeposition method to immobilize a hierarchical NiCoP/NiCoSx heterostructure on Ni foam (NF) for alkaline HER. The strong interfacial coupling effect between NiCoP and NiCoSx not only offers abundant active sites for fast electrochemical reaction, but also enhances the charge transfer ability accompanied by high electrical conductivity. Consequently, the obtained self-supporting NiCoP/NiCoSx/NF exhibits an excellent catalytic performance with low overpotentials of 68, 144 and 222 mV to deliver current densities of 10, 100 and 500 mA cm-2 in 1 M KOH, along with good stability for more than 110 h, outperforming most of the reported non-noble metal based HER catalysts. Density functional theory (DFT) results further confirm that this bimetal phosphide/sulfide heterostructure can synergistically optimize the Gibbs free energy of H* during the HER process, thus accelerating the HER reaction kinetics. This work provides a new strategy toward the rational design of large-current-density electrocatalysts, which have great potential in practical large-scale hydrogen production.

Vapor-Mediated Infiltration of Nanocatalysts for Low-Temperature Solid Oxide Fuel Cells Using Electrosprayed Dendrites.

Electrode architecturing for fast electrochemical reaction is essential for achieving high-performance of low-temperature solid oxide fuel cells (LT-SOFCs). However, the conventional droplet infiltration technique still has limitations in terms of the applicability and scalability of nanocatalyst implementation. Here, we develop a novel two-step precursor infiltration process and fabricate high-performance LT-SOFCs with homogeneous and robust nanocatalysts. This novel infiltration process is designed based on the principle of a reversible sol-gel transition where the gelated precursor dendrites are uniformly deposited onto the electrode via controlled nanoscale electrospraying process then resolubilized and infiltrated into the porous electrode structure through subsequent humidity control. Our infiltration technique reduces the cathodic polarization resistance by 18% compared to conventional processes, thereby achieving an enhanced peak power density of 0.976 W cm-2 at 650 °C. These results, which provide various degrees of freedom for forming nanocatalysts, exhibit an advancement in LT-SOFC technology.

Engineering porous structure in Bi-component-active ZnO quantum dots anchored vanadium nitride boosts reaction kinetics for zinc storage

The electrochemical performance of aqueous zinc-ion battery (AZIB) is largely dependent on the fast reaction kinetics, therefore, researchers made a lot of research to improve the ion/electron transfer rate, but did not achieve satisfactory results. Herein, pore engineering is performed by a simple self-sacrificial strategy to obtain bi-component-active ZnO quantum dots (QDs) modified VN nanosheets (ZnO-QDs-VN-0.5) with an interconnected framework. The abundant and evenly distributed porous structure provides a short Zn 2+ ion channel for rapid diffusion. Compared to bulk VN-0.5, a unique high-surficial fast electrochemical reaction process is realized by rationally design the electrode. The formed ZnO-QDs-VN-0.5 exhibits a satisfactory specific capacity (384.1 mAh g −1 at 0.1 A g −1 ), good rate capability and satisfactory cycle life. Moreover, the flexible quasi-solid-state ZnO-QDs-VN-0.5//Zn battery also shows excellent stability, high energy density and power density, which proves that this material can be applied in different fields. The excellent performance may be due to the reasonable adjustment of the multi-phase interface and porous structure control, which significantly promotes the transfer rate of ions of ZnO-QDs-VN-0.5 (D Zn 2+ ≈10 −8 cm 2 s −1 ), and greatly enhances the ion storage sit. In addition, the mechanism of the electrochemical reaction was elucidated by different ex-situ methods. This work provides great hope for the preparation of porous electrode materials and provides a basis for guiding the construction of electrode materials with excellent performance. • The ZnO-QDs-VN-0.5 is used as the cathode material of AZIBs for the first time. • The ZnO-QDs-VN-0.5 cathode deliver high capacity and excellent long cycle stability. • The flexible quasi-solid-state ZnO-QDs-VN-0.5//Zn battery also shows excellent stability. • The Zn-storage mechanism of ZnO-QDs-VN cathode was discussed.

Construction of all-carbon micro/nanoscale interconnected sulfur host for high-rate and ultra-stable lithium-sulfur batteries: Role of oxygen-containing functional groups

Carbon nanotubes (CNTs) are often used to settle down the sluggish reaction kinetics in lithium–sulfur batteries (LSBs). However, the self-aggregation of CNTs often makes them fail to effectively inhibit the shuttling effect of soluble lithium polysulfide (LiPS) intermediates. Herein, a type of ultra-stable carbon micro/nano-scale interconnected “carbon cages” has been designed by incorporating polar acid-treated carbon fibers (ACF) into three-dimensional (3D) CNT frameworks during vacuum filtration processes. Results show that the ACF-CNT composite frameworks possess a reinforced-concrete-like structure, in which the ACFs can well work as the main mechanical supporting frames for the composite electrodes, and the oxygen-containing functional groups (OFGs) formed on them as cross linker between ACFs and CNTs. Benefitted from this design, the ACF-CNT/S cathodes deliver an excellent rate capability (retain 72.6% at 4C). More impressively, the ACF-CNT/S cathodes also show an ultrahigh cycling stability (capacity decay rate of 0.001% per cycle over 350 cycles at 2C). And further optimization suggests that the suitable treatment on CFs could balance the chemical adsorption (OFGs) and physical confinement (carbon cages), leading to fast and durable electrochemical reaction dynamics. In addition, the assembled soft-pack LSBs further show a high dynamic bending stability.

Self-formed carbon layer on calcium Metal-organic framework and rGO composite with High-stable K-storage performance in K-ion batteries

Potassium ion (K-ion) batteries are expected to be utilized as potential energy storage devices to replace the commercialized lithium ion (Li-ion) batteries in the upcoming large-scale system due to their abundant potassium resources as well as fast ion transport capability. Nevertheless, developing superior anode materials that can store K+ with a large ion radius has been the hotspot and leading edge. Herein, a self-formed carbon layer on calcium metal–organic framework and rGO composite with high-stable K-storage performance was initially introduced as an advanced anode material for K-ion battery. Due to the in-situ formed carbon coating layer on the surface by proper thermal treatment, the highly stable crystal structure and molecule structure of CaC8H4O4, as well as enhanced electronic conductivity from the two-dimentional rGO, the as-prepared CaC8H4O4/rGO-450 composite could exhibit excellent cyclic stability and rapid electrochemical reaction rate with a reversible capacity of 110 mAh g−1 over 700 cycles at the current density of 100 mAg−1. This work provides guidelines for the further realization of the preparation of K-ion battery anode materials with a fast electrochemical reaction rate, high rate and long life.

Coordinately Unsaturated Manganese-Based Metal-Organic Frameworks as a High-Performance Cathode for Aqueous Zinc-Ion Batteries.

The slow Zn2+ intercalation/deintercalation kinetics in cathodes severely limits the electrochemical performance of aqueous zinc-ion batteries (ZIBs). Herein, we demonstrate a new kind of coordinately unsaturated manganese-based metal-organic framework (MOF) as an advanced cathode for ZIBs. Coordination unsaturation of Mn is performed with oxygen atoms of two adjacent -COO-. Its proper unsaturated coordination degree guarantees the high-efficiency Zn2+ transport and electron exchange, thereby ensuring high intrinsic activity and fast electrochemical reaction kinetics during repeated charging/discharging processes. Consequently, this MOF-based electrode possesses a high capacity of 138 mAh g-1 at 100 mA g-1 and a long life span (93.5% capacity retention after 1000 cycles at 3000 mA g-1) due to the above advantages. Such distinct Zn2+ ion storage performance surpasses those of most of the recently reported MOF cathodes. This concept of adjusting the coordination degree to tune the energy storage capability provides new avenues for exploring high-performance MOF cathodes in aqueous ZIBs.

In-situ TEM observation of fast and stable reaction of lithium polysulfide infiltrated carbon composite and its application as a lithium sulfur battery electrode for improved cycle lifetime

Lithium sulfur batteries (LSB) are attracting attention as a next generation energy storage device because of their high energy density, low cost, and environmental friendliness surpassing that of lithium ion batteries (LIBs). An in-situ transmission electron microscopy experiment performed in this work revealed a fast electrochemical reaction and minimum volume changes during lithiation and delithiation for lithium polysulfide infiltrated vat black particles. Based on this observation, we developed a simple and cost-effective method for the lithium polysulfide battery to achieve high performance by employing a nanostructured vat black/carbon cloth electrode that exhibits high electrical conductivity, good mechanical properties, and a high surface area. These benefits enabled a high sulfur loading mass, captured the lithium polysulfide intermediate reaction products, and avoided structural changes. As a result, high specific discharge capacity of 1300 mAhg−1 at 0.2 C, an outstanding rate performance (846 mAhg−1 at 2 C) and an areal capacity of up to 3.352 mAhcm−2 with a sulfur loading mass of 3.8 mg were achieved. Increasing the sulfur loading mass to 7 mg (areal capacity of up to 4.24 mAhcm−2) still resulted in a desirable discharge capacity of 928 mAhg−1. This work provides a promising path towards practical lithium sulfur batteries.

Dual Pseudocapacitive Oxides Accelerate Kinetics of Sulfur Intermediates in Lithium-Sulfur Batteries

The sluggish electrochemical kinetics of sulfur species has impeded the wide adoption of lithium-sulfur battery, which is one of the most promising candidates for next-generation energy storage system. Here, we present the electronic and geometric structures of all possible sulfur species and construct an electronic energy diagram to unveil their reaction pathways in batteries, as well as the molecular origin of their sluggish kinetics. By decoupling the contradictory requirements of accelerating charging and discharging processes, we select two pseudocapacitive oxides to enable the efficient transport of electron/Li+ to and from sulfur intermediates respectively. After incorporating Li x Nb2O5/Nb2O5 as electron-ion source and MnO2/Li y MnO2 as electron-ion drain, the electrochemical kinetics of sulfur cathode is significantly accelerated by a factor of 5 times and 1.8 times, respectively. This strategy, which couples a fast-electrochemical reaction with a spontaneous chemical reaction to bypass a slow-electrochemical reaction pathway, offers a solution to accelerate an electrochemical reaction, providing new perspectives for the development of high-energy battery systems.