Multifunctional Electrocatalytic Cathodes Derived from Metal–Organic Frameworks for Advanced Lithium-Sulfur Batteries

The rechargeable lithium-sulfur (Li-S) battery is a promising candidate for the next generation of energy storage technology, owing to the high theoretical capacity, high specific energy density, and low cost of electrode materials. The main drawbacks in the development of long-life Li-S batteries are capacity fading and the sluggish kinetics at the cathode caused by the polysulfides shuttle. These limitations are addressed through the design of novel nanocages containing cobalt phosphide (CoP) nanoparticles embedded in highly porous nitrogen-doped carbon (CoP-N-GC) by thermal annealing of ZIF-67 in a reductive atmosphere followed by a phosphidation step using sodium hypophosphite. The CoP nanoparticles, with large surface area and uniform homogeneous distribution within the N-doped nanocage graphitic carbon, act as electrocatalysts to suppress the shuttle of soluble polysulfides through strong chemical interactions and catalyze the sulfur redox. As a result, the S@CoP-N-GC electrode delivers an extremely high specific capacity of 1410 mA h g⁻¹ at 0.1 C (1 C=1675 mA g⁻¹) with an excellent coulombic efficiency of 99.7 %. Moreover, capacity retention from 864 to 678 mA h g⁻¹ is obtained after 460 cycles with a very low decay rate of 0.046 % per cycle at 0.5 C. Therefore, the combination of the CoP catalyst and polar conductive porous carbon effectively stabilizes the sulfur cathode, enhancing the electrochemical performance and stability of the battery.     

A Rechargeable Al/S Battery with an Ionic‐Liquid Electrolyte

Aluminum metal is a promising anode material for next generation rechargeable batteries owing to its abundance, potentially dendrite‐free deposition, and high capacity. The rechargeable aluminum/sulfur (Al/S) battery is of great interest owing to its high energy density (1340 Wh kg^?1) and low cost. However, Al/S chemistry suffers poor reversibility owing to the difficulty of oxidizing AlS_x. Herein, we demonstrate the first reversible Al/S battery in ionic‐liquid electrolyte with an activated carbon cloth/sulfur composite cathode. Electrochemical, spectroscopic, and microscopic results suggest that sulfur undergoes a solid‐state conversion reaction in the electrolyte. Kinetics analysis identifies that the slow solid‐state sulfur conversion reaction causes large voltage hysteresis and limits the energy efficiency of the system.     

Catalytically Active CoSe2 Supported on Nitrogen-Doped Three Dimensional Porous Carbon as a Cathode for Highly Stable Lithium-Sulfur Battery

Lithium-sulfur batteries are promising secondary energy storage devices that are mainly limited by its unsatisfactory cyclability owing to inefficient reversible conversion of sulfur and lithium sulfide on the cathode during the discharge/charging process. In this study, nitrogen-doped three-dimensional porous carbon material loaded with CoSe₂ nanoparticles (CoSe₂-PNC) is developed as a cathode for lithium-sulfur battery. A combination of CoSe₂ and nitrogen-doped porous carbon can efficiently improve the cathode activity and its conductivity, resulting in enhanced redox kinetics of the charge/discharge process. The obtained electrode exhibits a high discharge specific capacity of 1139.6 mAh g⁻¹ at a current density of 0.2 C. After 100 cycles, its capacity remained at 865.7 mAh g⁻¹ thus corresponding to a capacity retention of 75.97 %. In a long-term cycling test, discharge specific capacity of 546.7 mAh g⁻¹ was observed after 300 cycles performed at a current density of 1 C.     

高效的尖晶石铁钴氧/氮掺杂有序介孔碳催化剂应用于可充电锌-空气电池

以电催化为核心的新能源储存和转换技术为缓解能源与环境问题提供了有效手段.可充电锌空气电池因其理论能量密度(1086 Wh·kg–1)高、成本效益显著、安全系数高、环境友好及放电平稳等优点被认为是一种具有前景的能源存储/转换装置,有望在新能源汽车、便携式电源等领域广泛应用.氧还原反应(ORR)和氧析出反应(OER)是锌-空气电池中的核心反应,目前,虽然贵金属催化剂对上述反应表现出一定的电催化活性,但由于其稀缺性、高昂价格和低稳定性因素严重阻碍了它们在锌-空气电池中的广泛应用.而非贵金属催化剂所面临的瓶颈在于ORR/OER反应动力学缓慢,导致其在实际应用过程中存在电压效率低和催化剂腐蚀等问题.因此,为了推进锌-空气电池商业化进程,研制低成本、高效、稳定的非贵金属催化剂迫在眉睫.本文通过一步法将双金属前驱体嵌入氮掺杂有序介孔碳(NOMC)中,合成了具有尖晶石型铁钴氧化物的高性能非贵金属电催化剂(FexCo/NOMC,x代表铁钴的摩尔比).实验结果表明,在x=0.5时,所制备的催化剂具有最佳的催化活性,与商业贵金属催化剂相比,该催化剂展现更优的电催化活性和稳定性.电化学测试结果表明,其ORR的半波电位为0.89 V(vs.RHE),当OER电流密度为10 mA·cm–1时,过电势仅为0.31 V,且电流-时间曲线测试结果表明催化剂表现出较好的稳定性.通过X射线光电子能谱(XPS)、穆斯堡尔谱(M?ssbauer)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)和拉曼光谱(Raman)等表征手段对电催化剂的物化性质进行表征,结果表明该材料优异的氧电催化性能归因于双金属氧化物的电子调控作用、NOMC的介孔结构、高导电性和高比表面积,其ORR与OER的催化活性位点分别是氮活化的碳(N-C)和双金属氧化物.以优化的Fe0.5Co/NOMC为正极组装可充电锌-空气电池,该电池在空气环境下展现出优良的充放电性能,其在电流密度为100 mA·cm–2条件下操作时能量密度达到820 Wh·kg–1,在1.0 V时功率密度达到153 mW·cm–2,它还表现出较好的稳定性,经过144 h的循环实验,活性没有明显下降.本文不仅制备了一种有前景的尖晶石型氧化物碳基氧电催化材料,还为高效氧电催化剂的合理开发与构筑提供了一条新的思路.     

A Bimetallic Zn/Fe Polyphthalocyanine‐Derived Single‐Atom Fe‐N4 Catalytic Site:A Superior Trifunctional Catalyst for Overall Water Splitting and Zn–Air Batteries

Developing an efficient single‐atom material (SAM) synthesis and exploring the energy‐related catalytic reaction are important but still challenging. A polymerization–pyrolysis–evaporation (PPE) strategy was developed to synthesize N‐doped porous carbon (NPC) with anchored atomically dispersed Fe‐N₄ catalytic sites. This material was derived from predesigned bimetallic Zn/Fe polyphthalocyanine. Experiments and calculations demonstrate the formed Fe‐N₄ site exhibits superior trifunctional electrocatalytic performance for oxygen reduction, oxygen evolution, and hydrogen evolution reactions. In overall water splitting and rechargeable Zn–air battery devices containing the Fe‐N₄ SAs/NPC catalyst, it exhibits high efficiency and extraordinary stability. This current PPE method is a general strategy for preparing M SAs/NPC (M=Co, Ni, Mn), bringing new perspectives for designing various SAMs for catalytic application.     

A carbonyl-rich covalent organic framework as a high-performance cathode material for aqueous rechargeable zinc-ion batteries

Aqueous rechargeable zinc-ion batteries (ZIBs) provide high theoretical capacity, operational safety, low-cost and environmental friendliness for large-scale energy storage and wearable electronic devices, but their future development is plagued by low capacity and poor cycle life due to the lack of suitable cathode materials. In this work, a covalent organic framework (Tp-PTO-COF) with multiple carbonyl active sites is synthesized and successfully introduced in aqueous rechargeable ZIBs for the first time. Tp-PTO-COF delivers high specific capacities of 301.4 and 192.8 mA h g⁻¹ at current densities of 0.2 and 5 A g⁻¹, respectively, along with long-term durability and flat charge–discharge plateaus. The remarkable electrochemical performance is attributed to the abundance of nucleophilic carbonyl active sites, well defined porous structure and inherent chemical stability of Tp-PTO-COF. Moreover, the structural evolution and Zn²⁺ ion intercalation mechanism are discussed and revealed by the experimental analysis and density functional theory calculations. These results highlight a new avenue to develop organic cathode materials for high performance and sustainable aqueous rechargeable ZIBs.

A covalent organic framework (Tp-PTO-COF) with carbonyl active sites was proposed as a novel cathode material and successfully applied in aqueous rechargeable zinc-ion batteries (ZIBs).     

Rechargeable Room‐Temperature Na–CO2 Batteries

Developing rechargeable Na–CO₂ batteries is significant for energy conversion and utilization of CO₂. However, the reported batteries in pure CO₂ atmosphere are non‐rechargeable with limited discharge capacity of 200 mAh g^?1. Herein, we realized the rechargeability of a Na–CO₂ battery, with the proposed and demonstrated reversible reaction of 3 CO₂+4 Na?2 Na₂CO₃+C. The battery consists of a Na anode, an ether‐based electrolyte, and a designed cathode with electrolyte‐treated multi‐wall carbon nanotubes, and shows reversible capacity of 60000 mAh g^?1 at 1 A g^?1 (≈1000 Wh kg^?1) and runs for 200 cycles with controlled capacity of 2000 mAh g^?1 at charge voltage <3.7 V. The porous structure, high electro‐conductivity, and good wettability of electrolyte to cathode lead to reduced electrochemical polarization of the battery and further result in high performance. Our work provides an alternative approach towards clean recycling and utilization of CO₂.     

Towards Highly Stable Storage of Sodium Ions: A Porous Na3V2(PO4)3/C Cathode Material for Sodium‐Ion Batteries

A porous Na₃V₂(PO₄)₃ cathode material coated uniformly with a layer of approximately 6 nm carbon has been synthesized by the sol–gel method combined with a freeze‐drying process. The special porous morphology and structure significantly increases the specific surface area of the material, which greatly enlarges the contact area between the electrode and electrolyte, and consequently supplies more active sites for sodium ions. When employed as a cathode material of sodium‐ion batteries, this porous Na₃V₂(PO₄)₃/C exhibits excellent rate performance and cycling stability; for instance, it shows quite a flat potential plateau at 3.4 V in the potential window of 2.7–4.0 V versus Na⁺/Na and delivers an initial capacity as high as 118.9 and 98.0 mA h g^?1 at current rates of 0.05 and 0.5 C, respectively, and after 50 cycles, a good capacity retention of 92.7 and 93.6 % are maintained. Moreover, even when the discharge current density is increased to 5 C (590 mA g^?1), an initial capacity of 97.6 mA h g^?1 can still be achieved, and an exciting capacity retention of 88.6 % is obtained after 100 cycles. The good cycle performance, excellent rate capability, and moreover, the low cost of Na₃V₂(PO₄)₃/C suggest that this material is a promising cathode for large‐scale sodium‐ion rechargeable batteries.     

Development of polymer‐based lithium secondary battery

Novel polymer composites based on polydisulfide compounds are developed as a high energy density cathode material for lithium rechargeable batteries. A polymer composite composed of 2,5‐dimercapto‐1,3,4‐thiadiazole (DMcT) and conducting polymer polyaniline (PAn) on a copper current collector provides high charge density exceeding 225Ah/kg‐cathode with average discharge voltage at 3.4V. The composite cathode showed excellent rate capability and cyclability (>500 cycles). Surface analysis and electrochemical studies indicate that a DMcT‐Cu complex plays an important role in the observed improvement of the battery performances with a copper current collector. Large increase in the charge density to 550Ah/kg‐cathode is achieved by adding elemental sulfur (S₈) to the DMcT/PAn composite cathode.     

Biomass Inspired Nitrogen Doped Porous Carbon Anode with High Performance for Lithium Ion Batteries

Ginkgo leave, a naturally abundant resource, has been successfully employed as the raw material to prepare nitrogen doped porous carbon (NDPC) materials. The preparation of the porous carbon does not involve assistance of any activation or template technique. The as‐obtained NDPC shows favorable features for electrochemical energy storage, which can not only provide multiple sites for the storage and insertion of Li ions, but also facilitate rapid mass transport of electrons and Li ions. As a result, the NDPC when evaluated as an anode material for lithium ion batteries delivers high reversible capacity (505 mAh·g^?1 at 0.1 C), excellent rate capability (190 mAh·g^?1 at 10 C). These favorable properties suggest that the NDPC can be a promising anode material for lithium ion batteries (LIBs).     

Graphdiyne Hybrid Nanowall Arrays for High-capacity Aqueous Rechargeable Zinc Ion Battery

Development of aqueous rechargeable zinc ion battery is an important direction towards grid energy storage sought in various applications.At present,the efficient utilization of aqueous rechargeable zinc ion batteries has been seriously affected due to the defects nature of the cathode materials,such as poor capacity,limited rate performance,and limited cycle stability.Therefore,the search for high-performance cathode materials is a main challenge in this field.Herein,we in-situ prepared graphdiyne-wrapped K0.25·MnO2(K0.25·MnO2@GDY)hybrid nanowall arrays as the cathode of aqueous rechargeable zinc ion battery.The hybridnanowall arrays have obviously alleviated the pulverization and sluggish kinetic process of MnO2 cathode materials and shown high specific capacity(520 mA·h/g at a current density of 55 mA/g),which is near-full two-electron capacity.The high specific capacity was resulted from more than one Zn2+(de)intercalation process occurring per formula unit,in which we observed a structural evolution that partially stemmed from ion exchange between the intercalated K+and Zn2+ions during the discharge process.The present investigation not only provides a new material for the aqueous rechargeable Zn ion batteries,also contributes a novel route for the development of next generation aqueous rechargeable Zn ion batteries with high capacity.     

基于三维多孔活性炭构筑安全、高性能以及长循环寿命的锌离子混合电容器

可充电水系锌离子电池因成本低、环境友好等优点,已经成为目前电化学储能领域的研究热点之一。然而锌离子电池中高容量、长循环寿命的阴极材料的开发仍然是一大难题。为了解决这一问题,本文中通过直接利用锌片做阳极和集流体,采用高比表面积的三维多孔活性炭(3DAC)做阴极构筑了一种锌离子混合电容器(ZIHC)。该ZIHC器件表现出了优异的电化学性能,具有目前文献报道的ZIHC最高的213 mAh·g~(-1)比容量,展示出164Wh·kg~(-1)的高能量密度和9.3kW·kg~(-1)的高功率密度以及优异的循环稳定性(10 A·g~(-1)下循环20000圈之后,容量保持率为90%,库伦效率接近100%)。我们认为这种采用高比表、三维多孔活性炭(3DAC)做阴极构筑的安全、高性能以及长寿命的水系锌离子混合电容器将为下一代高性能储能器件的开发提供新的研究思路。     

Electrodeposited Co-Fe as an oxygen evolution catalyst for rechargeable zinc-air batteries

Cobalt-iron (Co-Fe) nanocubes were directly electrodeposited onto carbon paper and utilized as efficient oxygen evolution reaction catalysts for rechargeable zinc-air batteries. The morphology and mass loading were directly controlled by adjusting deposition time and the deposits evolved from single crystal nanocubes into a continuous film. Co-Fe catalysts exhibited low overpotential, small Tafel slopes and high durability during testing. A zinc-air battery using Co-Fe showed the same cycling efficiency as one using commercial Pt/Ru catalysts.     

一锅法制备Fe2O3@Fe-N-C氧还原电催化剂及其锌-空气电池的性能研究

在金属空气电池和燃料电池阴极上的氧还原反应(ORR)对相关电化学能量转换装置的整体性能有重要影响,金属-氮-碳催化剂有望替代传统的商业Pt-C成为新一代ORR电催化剂。本文通过简便的一步热解工艺合成了具有Fe-N_x活性位点和Fe₂O₃纳米颗粒共存的电催化剂,Fe₂O₃@Fe-N-C-1000催化剂在0.1 mol·L^-1 KOH溶液中表现出良好的ORR活性,半波电位为0.84 V,应用在锌-空气电池中时也具有可以和商业Pt-C媲美的性能,能量密度为88.3 mW·cm^-2,同时和Pt-C相比具有更好电化学稳定性,表现出优良的ORR应用潜力。     

Rechargeable aqueous Na–air batteries: Highly improved voltage efficiency by use of catalysts

The first rechargeable aqueous Na–air battery has been fabricated, and its electrochemical properties and reversibility are reported herein. The charge–discharge properties of the battery were tested using both Vulcan XC72R- and Pt/C-coated carbon paper as the air electrode. Pt/C-coated carbon paper exhibited a voltage efficiency of 84.3%, whereas, for Vulcan XC72R-coated carbon paper and uncoated carbon paper, the observed efficiencies were 78.0% and 72.4%, respectively. Use of Pt/C-coated carbon paper led to a high and stable discharging voltage of 2.85 V. The reported rechargeable aqueous Na–air battery is a potential candidate for high energy density batteries in the future.     

Large Scale Synthesis of Three-dimensional Hierarchical Porous Framework with High Conductivity and its Application in Lithium Sulfur Battery

Quick capacity loss due to the polysulfide shuttle effects and poor rate performance caused by low conductivity of sulfur have always been obstacles to the commercial application of lithium sulfur batteries. Herein, an in-situ doped hierarchical porous biochar materials with high electron-ion conductivity and adjustable three-dimensional (3D) macro-meso-micropore is prepared successfully. Due to its unique physical structure, the resulting material has a specific surface area of 2124.9 m² g⁻¹ and a cumulative pore volume of 1.19 cm³ g⁻¹. The presence of micropores can effectively physically adsorb polysulfides and mesopores ensure the accessibility of lithium ions and active sites and give the porous carbon material a high specific surface area. The large pores provide channels for the storage of electrolyte and the transmission of ions on the surface of the substrate. The combined effect of these three kinds of pores and the N doping formed in-situ can effectively promote the cycle and rate performance of the battery. Therefore, prepared cathode can still reach a reversible discharge capacity of 616 mAh g⁻¹ at a rate of 5 C. After 400 charge–discharge cycles at 1 C, the reversible capacity is maintained at 510.0 mAh g⁻¹. This new strategy has provided a new approach to the research and industrial-scale production of adjustable hierarchical porous biochar materials.     

Rechargeable Aluminium–Sulfur Battery with Improved Electrochemical Performance by Cobalt-Containing Electrocatalyst

The rechargeable aluminium–sulfur (Al–S) battery is regarded as a potential alternative beyond lithium-ion battery system owing to its safety, promising energy density, and the high earth abundance of the constituent electrode materials, however, sluggish kinetic response and short life-span are the major issues that limit the battery development towards applications. In this article, we report Co^II,III as an electrochemical catalyst in the sulfur cathode that renders a reduced discharge–charge voltage hysteresis and improved capacity retention and rate capability for Al–S batteries. The structural and electrochemical analysis suggest that the catalytic effect of Co^II,III is closely associated with the formation of cobalt sulfides and the changes in the valence states of the Co^II,III during the electrochemical reactions of the sulfur species, which lead to improved reaction kinetics and sulfur utilization in the cathode. The Al–S battery, assembled with the cathode consisting of Co^II,III decorated carbon matrix, demonstrates a considerably reduced voltage hysteresis of 0.8 V, a reversible specific capacity of ≈500 mAh g⁻¹ at 1 A g⁻¹ after 200 discharge–charge cycles and of ≈300 mAh g⁻¹ at 3 A g⁻¹.     

Multi‐Electron Reactions Enabled by Anion‐Based Redox Chemistry for High‐Energy Multivalent Rechargeable Batteries

The development of multivalent metal (such as Mg and Ca) based battery systems is hindered by lack of suitable cathode chemistry that shows reversible multi‐electron redox reactions. Cationic redox centres in the classical cathodes can only afford stepwise single‐electron transfer, which are not ideal for multivalent‐ion storage. The charge imbalance during multivalent ion insertion might lead to an additional kinetic barrier for ion mobility. Therefore, multivalent battery cathodes only exhibit slope‐like voltage profiles with insertion/extraction redox of less than one electron. Taking VS₄ as a model material, reversible two‐electron redox with cationic–anionic contributions is verified in both rechargeable Mg batteries (RMBs) and rechargeable Ca batteries (RCBs). The corresponding cells exhibit high capacities of >300 mAh g^?1 at a current density of 100 mA g^?1 in both RMBs and RCBs, resulting in a high energy density of >300 Wh kg^?1 for RMBs and >500 Wh kg^?1 for RCBs. Mechanistic studies reveal a unique redox activity mainly at anionic sulfides moieties and fast Mg²⁺ ion diffusion kinetics enabled by the soft structure and flexible electron configuration of VS₄.     

Multi-Electron Reactions Enabled by Anion-Based Redox Chemistry for High-Energy Multivalent Rechargeable Batteries

The development of multivalent metal (such as Mg and Ca) based battery systems is hindered by lack of suitable cathode chemistry that shows reversible multi-electron redox reactions. Cationic redox centres in the classical cathodes can only afford stepwise single-electron transfer, which are not ideal for multivalent-ion storage. The charge imbalance during multivalent ion insertion might lead to an additional kinetic barrier for ion mobility. Therefore, multivalent battery cathodes only exhibit slope-like voltage profiles with insertion/extraction redox of less than one electron. Taking VS₄ as a model material, reversible two-electron redox with cationic–anionic contributions is verified in both rechargeable Mg batteries (RMBs) and rechargeable Ca batteries (RCBs). The corresponding cells exhibit high capacities of >300 mAh g⁻¹ at a current density of 100 mA g⁻¹ in both RMBs and RCBs, resulting in a high energy density of >300 Wh kg⁻¹ for RMBs and >500 Wh kg⁻¹ for RCBs. Mechanistic studies reveal a unique redox activity mainly at anionic sulfides moieties and fast Mg²⁺ ion diffusion kinetics enabled by the soft structure and flexible electron configuration of VS₄.     

Dual‐Template Pore Engineering of Whey Powder‐Derived Carbon as an Efficient Oxygen Reduction Reaction Electrocatalyst for Primary Zinc‐Air Battery

Cost‐effective and high‐performance electrocatalysts for oxygen reduction reactions (ORR) are needed for many energy storage and conversion devices. Here, we demonstrate that whey powder, a major by‐product in the dairy industry, can be used as a sustainable precursor to produce heteroatom doped carbon electrocatalysts for ORR. Rich N and S compounds in whey powders can generate abundant catalytic active sites. However, these sites are not easily accessible by reactants of ORR. A dual‐template method was used to create a hierarchically and interconnected porous structure with micropores created by ZnCl₂ and large mesopores generated by fumed SiO₂ particles. At the optimum mass ratio of whey power: ZnCl₂ : SiO₂ at 1 : 3 : 0.8, the resulting carbon material has a large specific surface area close to 2000 m² g^?1, containing 4.6 at.% of N with 39.7% as pyridinic N. This carbon material shows superior electrocatalytic activity for ORR, with an electron transfer number of 3.88 and a large kinetic limiting current density of 45.40 mA cm^?2. They were employed as ORR catalysts to assemble primary zinc‐air batteries, which deliver a power density of 84.1 mW cm^?2 and a specific capacity of 779.5 mAh g^?1, outperforming batteries constructed using a commercial Pt/C catalyst. Our findings open new opportunities to use an abundant biomaterial, whey powder, to create high‐value‐added carbon electrocatalysts for emerging energy applications.