Hybrid Cathode Research Articles

Betavoltaic rechargeable Zn-ion battery based on hybrid cathode by combining betavoltaic structure with intercalation host

To address the issue of low power output of betavoltaic cells in practical applications, a 63Ni-powered betavoltaic rechargeable Zn-ion battery (BRZiB) is presented in this paper for simultaneously harvesting, converting, and storing beta-radioactive energy within one device. Experimentally, a patterned ZnO microrod array nanostructure was prepared using hydrothermal and lithography methods, in which a 63Ni beta source was deposited by chemical plating to form a 63Ni@ZnO structure for betavoltaic power generation. A carbon-coated VO2 nanocomposite (C@VO2), used as the intercalation host for Zn ions, was coated on the betavoltaic structure for fabricating the hybrid cathode of BRZiB. Without using any external power source, the 63Ni-powered BRZiB demonstrated a voltage rise of 0.3 V in 82 h, which was calculated to have an energy conversion efficiency of 5.1% and an energy density of 128 mWh/g over a half-life of 63Ni (∼100 years). The experimental results verify the effectiveness of multi-energy synergistic conversion in the electrochemical betavoltaic system.

Improvement in Rate Capabilities of Hybrid Cathodes with through-Holed Layers of Cathode Material and Activated Carbon on Each Side of a Current Collector in Lithium-Ion Batteries

This study was conducted to improve the rate capability and cyclability of cathodes for lithium-ion batteries (LIBs) with hybrid cathode structure. Through-holed LIB cathode material and activated carbon layers formed on each side of a current collector were drilled with a picosecond pulsed laser beam for preparing the cathode structure (Figure). The hybrid cathodes exhibited excellent rate capabilities of 93% capacity retention at 100 C. The results were dependent on the weight percentage of the activated carbon relative to the total weight of the active materials and on the difference in discharge/charge voltages between the LIB cathode and activated carbon materials. The cathode could have cycle stability at 50 C during 100 cycles. The performance characteristics of the hybrid cathode, the through-holed and nontreated LIB cathodes and the nontreated activated carbon cathodes were compared in a Ragone plot. In the plot, the hybrid cathode was located in the region where conventional through-holed and nontreated cathodes could not be located. Figure 1

Wet Procedure-Driven Performance Enhancement of Poly-Crystalline Cathodes in All-Solid-State Batteries

As the demand for electrical energy continues to rise, battery systems have gained significant attention. All-solid-state batteries (ASSBs) have emerged as promising candidates for the next generation of energy storage systems due to their enhanced safety and high energy density. By replacing the flammable organic liquid electrolytes used in conventional lithium-ion batteries (LIBs) with solid-state alternatives, ASSBs offer enhanced safety features, eliminating risks of leakage, fire, and explosions. Furthermore, recent research efforts have been directed towards improving energy density by increasing the capacity of nickel-rich layered oxide cathode materials (NCM), facilitating safer and more efficient energy storage system[1].Conventional dry methods for manufacturing bulk-type electrodes in all-solid-state batteries (ASSBs) are limited in scalability, posing challenges for commercialization. Wet-slurry casting methods are essential for synthesizing large-area cathodes; however, difficulties arise due to the severe reactivity between sulfide solid electrolytes (SEs), such as Li6PS5Cl (LPSCl), and polar solvents like N-Methyl-2-pyrrolidone (NMP).Kim et al. proposed an infiltration method as a solution to address this issue. By elevating the temperature during the infiltration process, we enhance the molecular motion of the SE, facilitating its efficient incorporation into the cathode structure. This approach enabled the fabrication of a high-energy-density NCM622/Li–In half cell with a capacity of 136 mA h g-1 and a loading level of 17 mg cm-2. Electrochemical testing with cathode materials of varying particle sizes revealed that hybrid cathodes containing a mixture of large and small particles exhibited optimal SE infiltration, minimizing void formation within the electrode. Among the fabricated ASSBs, those with SE–NCM electrodes comprising a blend of active materials demonstrated superior electrochemical performance, achieving a capacity of 108.6 mA h g-1[2].In this study, a scalable infiltration sheet-type process was used to fabricate composite electrodes with different cathode-material morphologies for ASSBs. LPSCl-infiltrated polycrystalline electrodes showed an excellent retention performance and rate capability. Galvanostatic intermittent titration technique (GITT) analysis and transmission electron microscopy (TEM) confirmed severe polarization and the presence of a rock-salt-structure layer in single-crystalline cathode particles. In contrast, composite electrodes comprising polycrystalline cathode materials infiltrated with the SE LPSCl showed an excellent electrochemical performance owing to intimate electrode–electrolyte interfacial contact. The as-fabricated poly-NCM infiltration electrodes showed an excellent electrochemical performance (with an initial discharge capacity of 196 mA h g−1, a discharge capacity of 112 mA h g−1 at a high rate of 2 C, and a retention of 81 % after 30 charge–discharge cycles). The infiltration method proposed in this study could enable the fabrication of high-performance composite electrodes for ASSBs in the future.

Solid-State Architecture Batteries for Enhanced Rechargeability and Safety (SABERS) Beyond Li-Ion: Technology to Enable Next-Generation Sustainable Electric Aviation

All-electric vertical take-off and landing vehicles (eVTOL) for urban air mobility (UAM) concepts face numerous challenging technical barriers before their introduction into the consumer marketplace. The primary barrier to overcome is developing an energy storage system that meets rigorous aerospace safety and performance criteria. The performance metrics for eVTOL vehicles are at least two times greater than those of electric ground vehicles. Furthermore, inherently non-flammable batteries are essential for the safe operation of commercial electric aero vehicles. The SABERS concept proposes a battery that meets the critical performance criteria by developing a solid-state architecture battery utilizing a high-capacity sulfur-selenium cathode and lithium metal anode. The combination of sulfur and selenium offers a balanced energy-to-power density ratio, which can be tailored to the specific application by altering the stoichiometric ratios of sulfur to selenium. This hybrid cathode will be developed using NASA-patented holey graphene technology as a highly conductive, ultra-lightweight electrode scaffold. A solid-state electrolyte will be used as a safe, non-flammable replacement for the highly flammable liquid organic electrolytes currently in SOA lithium-ion batteries. This solid-state lithium-sulfur/selenium cell will be designed in a serial stacking configuration to enable the dense packaging of the battery cells. The serial stacking configuration is termed a bipolar stack, which has the advantages of reducing overall cell weight, simplifying the interfaced connections for the cell, and minimizing the cooling requirements. Lastly, the optimization of battery components will occur through a robust and rigorous combination of various computational modeling techniques covering multiple length scales. The expected result will be a fully solid-state battery with operational temperatures up to 150 °C, providing the required energy density, discharge rates, and inherent safety to meet the strict aerospace mission performance criteria. The SABERS team employed novel materials development, computational modeling, and design-of-experiments (DOE) optimization studies in their research. This presentation will show the results of these studies and demonstrate a feasible path for solid-state cells with a specific energy greater than 400 Wh/kg to enable electric aircraft. Figure 1

Organic-inorganic hybrid cathode enabled by in-situ interface polymerization engineering boosts Zn2+ desolvation in aqueous zinc-ion batteries

Rechargeable aqueous zinc-ion batteries (RAZIBs) have attracted considerable attention for application in large-scale energy storage systems. However, the progress of RAZIBs has been hindered by the sluggish reaction kinetics and poor structural stability, which are closely associated with the desolvation process of hydrated Zn2+. To overcome these issues, an in situ interfacial polymerization strategy is proposed to uniformly germinate a polyaniline (PANI) layer on α-MnO2 and form an organic–inorganic hybrid cathode (MnO2@PANI). Theoretical calculations and experimental characterizations disclose that the polyaniline layer equipped with hydrophilic functional groups can effectively trap the active water molecules to break the strong attraction between H2O and Zn2+, thereby facilitating the desolvation process of hydrated Zn2+, and regulating the Zn2+ diffusion kinetics and electrode reaction kinetics on the cathode/electrolyte surface. Meanwhile, the irreversible phase evolution and dissolution of active species are largely suppressed due to the PANI shell protecting the α-MnO2 from the attack of active water molecules. As a consequence, the organic–inorganic hybrid cathode exhibits 401.9 mAh/g after 200 cycles at a current density of 0.5 A/g and long-term durability over 1000 cycles at a current density of 2.0 A/g without irreversible phase transformation. This work provides insight into the regulation of the desolvation process for high performance aqueous energy storage systems.

Efficiently controllable synthesis of high performance Na3V2(PO4)2O2F/C hybrid cathode with robust micro-nano architecture

The Na3V2(PO4)2O2F (NVPOF) is synthesized with high conversion rates and uniform morphology, by rapid precipitation of adjusting the pH and temperature. And the effect of reaction temperature on the performance is mainly investigated, and the results show that the rise of reaction temperature is beneficial to the increase of F content and conversion rate. Furthermore, micro morphology can be designed by adjusting temperature and other conditions. Then the NVPOF/C with modification of robust carbon coating is conducted, and the surface structure has been characterized. The optimized NVPOF/C based hybrid exhibits a specific capacity of 116.7 mAh·g−1 at 0.1C and it has long cycle performance (92.0 % retention rate after 200 cycles at 1C) and high capacity at high current density (78 mAh·g−1 at 10C). Consequently, a simple and controllable precipitation method is provided to prepare micro-nano NVPOF/C with high rate performance and indicate the importance of morphology and surface stability control.

Boosting Zn2+ Intercalation in High-Performance Aqueous Zinc-Ion Batteries with Coupling-Induced Biphase Interface.

Effectively addressing the trade-off between fast charging kinetics and long cycle life of aqueous zinc ion batteries (AZIBs) has proven challenging due to JahnTeller distortion and high lattice strain induced by inserted Zn2+ ions in cathode structures. Herein, a hybrid cathode of NiCo2O4-MnO2 with abundant electrochemical phase interfaces and interface coupling induced defects is developed via a simple electrochemical oxidation strategy to boost rich redox reactions. The formation of Ni─O─Mn and Co─O─Mn bonds promoted the electron transfer between the biphase interface, adjusted the electron density of the material body, effectively alleviated the electrostatic effect between Zn2+ embedding and the main frame, and further maintained the stability of the structure and alleviated the dissolution of manganese. The resulting NiCo2O4-MnO2 cathode exhibited a high reversible specific capacity of 343.5 mA h g-1 at a current density of 100 mA g-1 and retained 95.5 % of its initial capacity after 1000 cycles at a current density of 1 A g-1. This discovery enriches insights into performance mechanisms at interfaces and paves the way for designing advanced energy storage materials.

Achieving Superior Cyclability Pouch Cells with Oxygen Vacancy-Moderated P'2/P3 Hybrid Layered Sodium Cathode Materials.

Layered P2-type sodium manganese oxide has emerged as a promising cathode candidate for sodium-ion batteries due to its appealing cost-effectiveness and high discharge voltage. However, its practical capacity within the voltage range of 2.0-4.0 V (vs Na+/Na) is relatively low, and its rate capability is hampered by the adverse charge/vacancy ordering during charge/discharge. In this study, a layered P'2/P3 mixed-phase Na0.8-aMn0.675Ni0.225Li0.1O2-x cathode with high (003) crystal plane intensity was designed by introducing oxygen vacancies to P2-structured materials. Aided by these advantages, the hybrid cathode material demonstrates impressive structural and thermal stability and faster Na-ion diffusion kinetics compared to a regular P2 material. Half-cell shows an initial discharge capacity retention of 101 mA h/g at 12 mA/g and 92.25% retention after 500 cycles at 120 mA/g. In combination with a hard carbon anode, the 0.5 A h pouch cell achieved a prevailing capacity retention of 95.2% after 2600 cycles at 36 mA/g. This work opens new dimensions for layered cathode materials with the aim of achieving superior cyclabilities.

A novel fuel cell cathode hybrid intake structure design and control for integrated hydrogen energy utilization system

The typical Integrated Hydrogen Energy Utilization System (IHEUS) does not recycle oxygen. For maximizing the system's efficiency, this study proposes a method for recycling byproduct oxygen in a Fuel Cell (FC) hybrid cathode intake structure and its control. By introducing the pure oxygen produced as a byproduct of hydrogen production into the FC, a hybrid cathode intake structure is formed with the air branch. To control this structure, models of the oxygen and air branch, and the FC stack are established. Subsequently, using BiLSTM network to learn historical data and extract relevant features, the output power demand of the FC system is predicted. Based on the prediction results, the required gas flow is calculated, and a fuzzy PID control strategy is employed to adjust the opening of the solenoid valve to change the gas flow to meet the demand. Finally, comparative studies show that our FC system, operating in a pure oxygen state, outperforms conventional air intake design: heat production increases by 13 %, electric efficiency improves by 20 %, and pure water savings reach 65.57 %. The air compressor witnesses a substantial 37.63 % reduction in power consumption, contributing to an overall energy efficiency increase of 8.92 % for the IHEUS.

High-Capacity and Ultra-Long-Life Mg-Metal Batteries Enabled by Intercalation-Conversion Hybrid Cathode Materials.

The advancement of rechargeable Mg-metal batteries (RMBs) is severely impeded by the lack of suitable cathode materials. Despite the good cyclic stability of intercalation-type compounds, their specific capacity is relatively low. Conversely, the conversion-type cathodes can deliver a higher capacity but often suffer from poor cycling reversibility and stability. Herein, a WSe2/Se intercalation-conversion hybrid material with elemental Se uniformly distributed into WSe2 nanosheets is fabricated via a simple solvothermal method for high-performance RMBs. The uniformly introduced Se confined in WSe2 nanosheets can not only efficiently improve the conductivity of the hybrid cathodes, facilitating the fast electron transport and ion diffusion, but also provide additional specific capacity. Besides, the WSe2 can effectively inhibit the detrimental Se dissolution and polyselenide shuttle, thereby activating the activity of Se and improving its utilization. Consequently, the synergy of intercalation and conversion mechanisms endows WSe2/Se hybrids with superior reversible capacity of 252mAhg-1at 0.1Ag-1 and ultra-long cyclability of up to 5000 cycles at 2.0Ag-1 with capacity retention of 78.1%. This work demonstrates the feasibility of the strategy by integrating intercalation and conversion mechanisms for developing high-performance cathode materials for RMBs.

Multi-layered carbon accommodation of MnO2 enabling fast kinetics for highly stable zinc ion batteries

Large-scale durable aqueous zinc ion batteries for stationary storage are realized by spray-coating conductive PEDOT(Poly(3,4-ethylenedioxythiophene)) wrapping MnO2/carbon microspheres hybrid cathode in this work. The porous carbon microspheres with multiple layers deriving from sucrose provide suitable accommodation for MnO2 active materials, exposing more redox active sites and enhancing the contact surface between electrolyte and active materials. As a result, MnO2/microspheres are adhered to the current collector by a conductive PEDOT coating without any binder. The ternary design retards the structural degradation during cycling and shortens the electron and ion transport path, rendering the full batteries high capacity and long cycle stability. The resulting batteries perform the capacity of 277, 227, 110, 85 and 50 mAh/g at 0.2, 0.5, 1, 2 and 5 A/g, respectively. After 3000 cycles the initial capacity retains 86%, and 80% after 5000 cycles. GITT indicates PEDOT wrapping MnO2/microspheres cathode enables better ion intercalating kinetics than conventional MnO2. The work could represent a novel and significant step forward in the studies on the large-scale application of zinc ion batteries.

Substantially boosted energy density of NiCoMn layered double hydroxides with nanocrystalline-amorphous domains

To promote the energy density (E) of the hybrid asymmetric supercapacitance (ASC) device, both anode and cathode materials are crucial. The multi-component layered double hydroxides (LDH) as anode materials boost a surprisingly supercapacitance, while the functions of dual-phase nanodomains induced by multi-constituents on the electrochemical reactions are still puzzled and need to be explored. In this work, Ni1Co1Mnx (Ni/Co/Mn = 1/1/x) LDH microspheres are developed, characterizing by quantum-sized nanocrystals embedded in amorphous matrix modulated via Mn doping. The specific capacities (C) of Ni1Co1Mn1.5 reach up to 5750 at 1 A g−1 and 5300 F g−1 at 10 A g−1, exceeding four times of 1367 (1 A g−1) and 1133 F g−1 (10 A g−1) of the Ni1Co1Mn0 counterpart. To break through the upper limit of the traditional active cardon cathode, bamboo-derived porous carbon (BPC) powders are produced from green raw resource by two stages calcination to increase the C. The assembled ASC cell with Ni1Co1Mn1.5 as an anode and BPC as a cathode possesses a large E of 97.8 Wh kg−1 at a power density (P) of 749.2 W kg−1. An exceptional sustainability of Ni1Co1Mn1.5//BPC device is attained with 91.4 % retention after 8000 cycles at a large charging current of 10 A g−1. The insights of Mn-regulated transition of nanocrystal-amorphous microstructure and the enhanced energy storage performance are explored.

Pressure-driven molecule implantation enabling ultrahigh-rate and ultralong-life zinc ion batteries

Durable cathode materials with high specific capacity are essential for aqueous zinc ion batteries (AZIBs). However, vanadium-based materials endure irreversible structural collapse, sluggish diffusion kinetics, and low working voltage. In this study, we propose a unique pressure-driven molecule implantation (PMI) strategy to fabricate a laminar organic–inorganic hybrid cathode (PMI-VO) for AZIBs by coupling polyaniline (PANI) with vanadium oxide. The bipolar protonation of implanted electroactive PANI provides abundant active sites for ion/electron transfer and Zn2+/H+ storage in PMI-VO. Importantly, the formed C-V-O interfacial coupling bonds in the cycling process effectively relieve the intercalation stress and strengthen the redox kinetics and structural integrity of V2O5. In situ infrared spectroscopy and theoretical calculations reveal the PMI-induced multiple ions storage mechanisms in the PMI-VO cathode. Accordingly, PMI-VO cathode performs a superior specific capacity of 522 mAh∙g−1 at 0.2 A∙g−1, a high operating voltage of 0.86 V, a high energy density (387.4 Wh∙kg−1), and splendid long-life stability (over 15,000 cycles at 20 A∙g−1 with 191 mAh∙g−1). Therefore, this pressure-driven molecule implantation strategy provides a pioneering method to fabricate superior cathode materials of advanced AZIBs.

Enhanced lithium battery cathode performance via mechanical grinding of CFx_MnO2 hybrid materials for space-grade applications: Unveiling synergistic effects

CFx_MnO2 hybrid cathode materials are prepared from a (C2F)n-type graphite fluoride (CFx) and industrial MnO2. Because of its physicochemical (insulating behavior, low content of CF2 and CF3 groups, no or a few remaining sp2 carbon atoms) and electrochemical properties (flat plateau on galvanostatic curve and theoretical capacity of 623 mAh/g, higher than other conventional cathodes for primary lithium battery), graphite fluoride of (C2F)n-type is selected to evidence synergetic effects with MnO2 that occur at the fluoride/oxide and electrolyte/ electrode interfaces. Both materials are mixed by mechanical ball-milling using different sets of parameters. The hybrid material presents very good electrochemical properties with a maximum energy density of about 1600 Wh per kg of active material. Notably, it shows a considerable improvement in voltage plateau and voltage delay compared to CFx. The parameters applied during ball-milling also shape the electrochemical performance of the new hybrid material. Ball milling increases the average discharge voltage plateau, and the power density of the battery, and avoids ohmic drop which may cause a battery to be eliminated as soon as it begins to discharge. More finely, electrochemical impedance spectroscopy shows that pushed grinding leads to more homogeneous but more polarized material-electrolyte interfaces so better diffusion and capacity but lower discharge potential.

Glutamic Acid Induced Proton Substitution of Sodium Vanadate Cathode Promotes High Performance in Aqueous Zinc‐Ion Batteries

AbstractLacking strategies to simultaneously address the narrow interlayer spacing, irreversible phase transitions, dissolution and electrical transport issues of vanadium oxides is restricting their application in aqueous zinc‐ion batteries. Herein, to address these challenges concurrently, an organic‐inorganic hybrid cathode is explored, HNaV6O16·4H2O‐Glu (HNVO‐Glu), through a guest material‐mediated NVO synthesis strategy utilizing glutamic acid (Glu) to induce Na substituted by proton and enable crystal transformation of Na2V6O16·3H2O (NVO). Specially, Glu insertion kills three birds with one arrow: i) induces the formation of a structurally stable monoclinic HNaV6O16·4H2O phase by introducing H into the NVO framework, preventing structural phase change and collapse of NVO material; ii) acts as a pillar to expand the interlayer spacing, which improves the Zn2+ diffusion kinetics; moreover, the polar groups on the Glu surface weaken the electrostatic interaction between Zn2+ and the host materials, further enhancing the zinc‐ionic transport rate; iii) enhances the electrical conductivity of HNVO by converting the p‐type semiconductor into the n‐type semiconductor structure. Consequently, the HNVO‐Glu exhibits a high specific capacity (354.6 mAh g−1 at 1 A g−1), excellent Zn2+ diffusion capability (10−9 to 10−7 cm2 s−1) and outstanding cycling stability with a capacity retention of 87.2% after 12 000 cycles at 10 A g−1.

Boosting Zn2+ intercalation in manganese oxides for aqueous zinc ion batteries via delocalizing the d-electrons spin states of Mn site

Rechargeable aqueous zinc-ion batteries (AZIBs) have received increasing attention on account of their eco-friendliness and low cost. However, the limited capacity and poor rate properties of cathodes remain a major challenge due to the low electrochemical reactivity of cathode materials and sluggish Zn2+ transport kinetics. Herein, we design a 1,5-naphthalenediamine (NAPD) pre-intercalate potassium manganese dioxide (KMO-NAPD) with high capacity and rate capability for AZIBs. The introduction of NAPD can delocalize the d-electrons spin states of the Mn site and activate the reactivity of KMO-NAPD for Zn2+ intercalation. Moreover, the interaction between intercalated Zn2+ and KMO-NAPD is weakened due to the decreased electrostatic interaction force, which promotes the diffusion of Zn2+. Consequently, the KMO-NAPD cathode exhibits high specific capacity (237 mAh g−1 at 1 A g−1) satisfying rate capability (129 mAh g−1 at 4 A g−1), and excellent cycling stability (85 % capacity retention after 1000 cycles). Furthermore, the fabricated AZIBs based on the KMO-NAPD exhibit a high energy density of 294.3 Wh kg−1 and a peak power density of 8.6 kW kg−1. This study opens up a new path for the development of high-energy organic-inorganic hybrid cathode materials with modulated electronic structures for advanced AZIBs.

Selenium-Doped Sulfurized Polyacrylonitrile Hybrid Cathodes with Ultrahigh Sulfur Content for High-Performance Solid-State Lithium Sulfur Batteries.

The solid-state lithium sulfur battery (SSLSB) is an attractive next-generation energy storage system by reason of its remarkably high energy density and safety. However, the SSLSB still faces critical challenges, such as sluggish reaction kinetics, mismatched interface, and undesirable reversible capacity. Herein, a high-performance SSLSB is reported using sulfurized polyacrylonitrile with rich selenium-doped sulfur (Se/S-S@pPAN) as a cathode and poly(ethylene oxide)/Li7La3Zr1.4Ta0.6O12 (PEO-LLZTO) as an electrolyte. The sulfur content of the cathode up to 60.9 wt % can be achieved by dispersing selenium sulfide (SeSx) species in the sulfurized polyacrylonitrile (S@pPAN) skeleton at a molecular level. Selenium as a eutectic accelerator can be uniformly distributed in the composite through the Se-S bond and can accelerate the reaction kinetics. The PEO-LLZTO hybrid solid-state electrolyte (SSE) displays an attractive electrochemical performance and provides an intimate contact with electrodes. At 60 °C, Se/S-S@pPAN delivers an impressive discharge capacity of 1042 mAh g-1 at 0.1C and 445 mAh g-1 at 1C. Additionally, the LiFePO4 cathodes combined with PEO-LLZTO deliver a high reversible capacity (158.9 mAh g-1, 1C) and an ultralong lifespan (a capacity retention of 80%, 1000 cycles) at 1C. The synergetic design of the high-performance sulfur cathode and the organic/inorganic hybrid electrolyte is crucial for enabling the high-performance SSLSB.

Halide Exchange in Perovskites Enables Bromine/Iodine Hybrid Cathodes for Highly Durable Zinc Ion Batteries.

With the increasing need for reliable storage systems, the conversion-type chemistry typified by bromine cathodes attracts considerable attention due to sizeable theoretical capacity, cost efficiency, and high redox potential. However, the severe loss of active species during operation remains a problem, leading researchers to resort to concentrated halide-containing electrolytes. Here, profiting from the intrinsic halide exchange in perovskite lattices, a novel low-dimensional halide hybrid perovskite cathode, TmdpPb2[IBr]6, which serves not only as a halogen reservoir for reversible three-electron conversions but also as an effective halogen absorbent by surface Pb dangling bonds, C─H…Br hydrogen bonds, and Pb─I…Br halogen bonds, is proposed. As such, the Zn||TmdpPb2[IBr]6 battery delivers three remarkable discharge voltage plateaus at 1.21V (I0/I-), 1.47V (I+/I0), and 1.74V (Br0/Br-) in a typical halide-free electrolyte; meanwhile, realizing a high capacity of over 336 mAh g-1 at 0.4 A g-1 and high capacity retentions of 88% and 92% after 1000 cycles at 1.2 A g-1 and 4000 cycles at 3.2 A g-1, respectively, accompanied by a high coulombic efficiency of ≈99%. The work highlights the promising conversion-type cathodes based on metal-halide perovskite materials.

DFT Simulations Investigating the Trapping of Sulfides by 1T-LixMoS2 and 1T-LixMoS2/Graphene Hybrid Cathodes in Li-S Batteries

The aim of this study is to investigate new materials that can be employed as cathode hosts in Li-S batteries, which would be able to overcome the effect of the shuttling of soluble polysulfides and maximize the battery capacity and energy density. Density functional theory (DFT) simulations are used to determine the adsorption energy of lithium sulfides in two types of cathode hosts: lithiated 1T-MoS2 (1T-LixMoS2) and hybrid 1T-LixMoS2/graphene. Initial simulations of lithiated 1T-MoS2 structures led to the selection of an optimized 1T-Li0.75MoS2 structure, which was utilized for the formation of an optimized 1T-Li0.75MoS2 bilayer and a hybrid 1T-Li0.75MoS2/graphene bilayer structure. It was found that all sulfides exhibited super-high adsorption energies in the interlayer inside the 1T-Li0.75MoS2 bilayer and very good adsorption energy values in the interlayer inside the hybrid 1T-Li0.75MoS2/graphene bilayer. The placement of sulfides outside each type of bilayer, over the 1T-Li0.75MoS2 surface, yielded good adsorption energies in the range of −2 to −3.8 eV, which are higher than those over a 1T-MoS2 substrate.

A hybrid cathode catalytic layer composed of M–N–C and Pt/C for direct methanol fuel cells with high methanol tolerance

Pt/C based direct methanol fuel cells (DMFCs) always suffer from a serious methanol crossover under a high concentration of methanol solution. In this paper, we report a novel hybrid cathode catalytic layer (CCL) consisting of a physical blend of Pt/C and Fe-N-C. DMFC based on the hybrid CCL with an optimized loadings (0.25 mg cm−2 Fe-N-C and 2 mgPt cm-2Pt/C) outputs a high power density of 28.87 mW cm−2 at 10 M methanol, and the single Pt/C based cell only shows a low power density of 12.04 mW cm−2 in comparison. Such a large improvement attributes to the increasing amount of reactive oxygen species (ROS), which is produced by Fe-N-C via an incomplete four-electron transfer process in oxygen reduction reaction (ORR). Inspired by this strategy, several M−N−C catalysts were synthesized, among which Cu-N-C shows the most brilliant performance to enhance the methanol tolerance of Pt/C. The peak power density of DMFC with Cu-N-C based hybrid CCL exceeds 31 mW cm−2 at 10 M methanol, which is superior to that of cells with Fe-N-C based hybrid CCL. This work provides a new approach for designing DMFCs with high energy density, which is practical for applications of portable power devices.