Active Material Loading Research Articles

High performance supercapacitors based on WS2 nanoflower electrodes with commercial-level mass-loading

Supercapacitors with a commercial-level mass loading of active materials are designed to offer greater energy storage capacity than conventional supercapacitors. For the first time, we are reporting the fabrication and performance studies of a symmetric supercapacitor with 30 mg cm−2 commercial-level mass loading of 2D WS2 nanoflower electrode material, which exhibited superior electrochemical performance. At 5 mV s–1 specific capacitance achieved by the device is 204 F g–1. At 1 A g–1, the supercapacitor provides impressive specific energy and power values of 14 Wh kg−1 and 0.8 kW kg−1, respectively. The device maintains an exceptional cycling stability of 100 % over 10,000 cycles of continuous charging and discharging. Furthermore, supercapacitor coin cells fabricated using commercial-level-mass loaded 2D WS2 electrodes are used to power an LED.

Reasonable design of thick electrodes in lithium-ion batteries

To achieve a high energy density for Li-ion batteries (LIBs) in a limited space, thick electrodes play an important role by minimizing passive component at the unit cell level and allowing higher active material loading within the same volume. Currently, the capacity of active materials is close to the theoretical capacity; therefore, thick electrodes provide the clearest solution for the development of high-energy-density batteries. However, further research is needed to resolve the electrochemical and mechanical instabilities inside the electrode owing to its increased thickness. This review summarizes the various methods and recent research aimed at fabricating electrodes with low-torsion and uniform pore structure for fast ion transport, based on an in-depth consideration of the challenges encountered in thick electrodes. In addition, future developments and research directions necessary to apply these methods to the industry are presented. This review will be a valuable milestone for manufacturing robust thick electrodes with high performance and for realizing ultrahigh-capacity/density batteries in the future.

Influences on Reliable Capacity Measurements of Hard Carbon in Highly Loaded Electrodes

AbstractFor the development of a full‐cell battery system, typically appropriate cathodes and anodes are characterized within a half‐cell setup where a metal counter electrode is installed to gather data about the employed electrodes. Ultimately, the individual capacity loadings allow for suitable balancing of the anode to cathode capacity in the full‐cell. This approach seems rather unproblematic for lithium‐ion batteries. For sodium‐ion batteries, however, we show that the high reactivity of sodium metal strongly influences hard carbon‐based electrode measurements within sodium‐ion half‐cells. As hard carbon is considered state‐of‐the‐art anode material, the presented results have high impact on the development of sodium ion batteries. Specifically, we show that the type of electrolyte, as well as cell‐ and measurement‐setup are key factors for reliable sodium half‐cell measurements of hard carbon. The investigated hard carbon electrodes have a high active material loading of 7.2 mg/cm2 (with 93 % active material content) resulting in an areal capacity of 2.4 mAh/cm2, which represent application‐relevant conditions.

Highly Reversible Lithium-Ion Battery with Excellent Rate Performance and Cycle Stability Based on a Ti3C2/CoS2 Composite Anode.

Transition metal sulfide (TMS) CoS2 is considered an ideal anode material for new-generation lithium-ion batteries (LIBs) because of its high specific capacity, high electrochemical activity, and low cost. However, CoS2 is prone to volume expansion and structural collapse when it participates in the internal conversion reaction of the battery, which limits its practical application. After analyzing the failure mechanism of CoS2 as the anode material of LIBs, the concept of nanoengineered materials is introduced here. CoS2 particles are nanosized and stabilized by constructing a composite structure on an alkali-treated two-dimensional Ti3C2 Mxene conductive network. Both experiments and theoretical calculations show that special Ti-O-Co bonds are formed at the interface of the Ti3C2/CoS2 composite through oxygen-containing functional groups. Ti-O-Co bonding with adjustable electronic characteristics can effectively promote the utilization rate of anode materials, electronic conductivity, and ionic diffusivity and thus enhance the redox reaction kinetics of the device. When the Ti3C2/CoS2 composite is used as the anode material for LIBs, it still provides a high specific capacity of 405.8 mAh g-1 after 100 cycles at 0.1 A g-1. After running for 1000 cycles at a high current of 1 A g-1, the capacity retention is still close to 100%. Also, high cycle stability under the condition of highly active material loading (10.58 mg cm-2) and low electrolyte/active material ratio (10 μL mg-1) is achieved. This work provides a new idea for the development of commercial LIBs as anode materials.

Cellulose degradation of cottonseed meal derived porous carbon for supercapacitor

Enzyme, as a type of biocatalyst, has a superior degradability on the biomass component. Herein, the cellulase degradation of cottonseed meal (CCM) is used as carbon source and potassium citrate as activating agent to fabricate O, S, N co-doped carbon materials. Cellulase pretreatment degrades the cellulose (from 12.48 wt% to 2.24 wt%) of cottonseed meal (CM) as well as creates the pore structure. Most importantly, the enzymolytic process can enhance the O content and improve the activation efficiency of potassium citrate. The optimized CCM-800-2 with hierarchical porous structure and high O (11.33 at%) content exhibits a high specific capacitance of 364 F g-1 in 6 M KOH electrolyte. In addition, the assembled potassium citrate-chitosan gel electrolyte-based symmetric supercapacitor with 20 mg cm-2 mass loading of active material shows a high energy density of 28.8 Wh kg-1. This study provides an efficient enzyme assisted pretreatment and low activator ratio strategy to prepare biomass-based porous carbon, and expects to fabricate more carbon materials using other carbon precursors.

High Energy Density Porous RuO2 micro-Supercapacitors Using Protic Ionic Liquid Electrolytes

The rapid development of the Internet of Things (IoT) demands reliable and long-term energy supply to microelectronic devices distributed over the network with high power performance and less maintenance required.[1] Micro-supercapacitors (MSCs) have come to the foreground as miniaturized energy storage devices showing outstanding power density and long cycle life. However, the low cell voltage and low energy density remain major bottleneck that prevents their adoption in real device applications. To this end, several studies have been devoted to the engineering of MSC electrode materials and structural architecting of current collectors within the limited available footprint. This approach could offer opportunities to enhance the electrochemically active surface and mass loading of active materials with fast ion diffusion kinetics, leading to high areal energy density performance.[2] Although several efforts have been put forth in this direction, the complex synthesis route, unfavourable interfacial and mechanical stability of the electrode, electrolyte compatibility issues, etc. remain an arduous challenge.[3] The low cell voltage is another major issue preventing from achieving high energy density values in MSCs as it is directly linked to the electrochemical stability window (ESW) of the electrolytes used.[4] In addition, liquid-state electrolytes currently employed are inappropriate for the microfabrication route as it is prone to evaporation, leakage, and potential safety issues. Hence, a lot of research attention has been given to developing solid-state electrolytes able to afford large operational windows and help promote the application of on-chip MSCs. In this work, we have demonstrated the use of protic ionic liquid (PIL)-based electrolytes able to provide pseudocapacitance in hydrous ruthenium dioxide (RuO2) electrodeposited on interdigitated MSC substrates with extended operational cell voltage. As a pseudocapacitive material, RuO2 exhibits excellent conductivity, high electrochemical reversibility, and cycling stability.[5] On the other hand, as room temperature molten salts, PILs help to overcome evaporation and encapsulation problems associated with the conventional aqueous electrolytes and flammability and safety issues linked to common organic electrolytes.[6-9] We explored pyrrolidinium-based PILs with varying alkyl substitutions, their structure-property, and electrochemical studies for RuO2 MSCs. To further expand the use of these PILs in real devices, 3D MSCs with higher active material mass loading was realised using interdigitated porous Au current collector substrates. The PIL-based porous RuO2 MSCs showed superior charge storage and higher energy density performance as compared to conventional aqueous electrolytes. To envision the practical application of RuO2 MSCs and their subsequent integration with microelectronic devices, ionogel-based solid-state electrolytes were developed. This work opens pathways to develop micro-supercapacitors exhibiting high energy and power density by combining pseudocapacitive metal oxide-based active materials and protic ionic-liquid-based non-aqueous electrolytes and help their integration with on-chip IoT devices.

(Invited) Using Synchrotron Techniques to Pry into Lithium-Ion Batteries Limitations

Li-ion batteries have been highly successful since they were introduced commercially some 30 years ago. However, there are still improvement to be made to reduce cost, charging times, energy density etc. In this talk, we will present the some of our recent synchrotron radiation-based work on the sub-processes that must work in unison for lithium battery operation, in particular at high current densities. Specifically, we will present work at the particle level on high power charging, illustrating how under favorable conditions some commercial cathode materials may be fully charged within tens of seconds. Moving towards the electrode scale, our latest technique development include an x-ray fluorescence technique that permits the determination of the electrolyte concentration within the electrode during battery operation. As such, this represent a major step forward towards validating mesoscale modeling as well as testing novel electrode architectures specifically designed for improved electrolyte transport. The importance of the electrode design is that in theory it can provide higher active material loading per area without losss of power capabilities. As such, the mass and volume of separator as well as current collector could be minimized improving both energy density and cost.

Hydrothermal synthesis of Ni,Co hydroxide nanosheet array on vertically suspended Ni foam for high performance supercapacitors

Ni(OH)2 have attracted great attention as pseudocapacitor electrode materials due to its high theoretical capacitance. However, the intrinsic disadvantaged in low electronic conductivity and sluggish ion diffusion kinetics of Ni(OH)2 limit its performance and practical application. Herein, we report a simple hydrothermal method to synthesize Co doped Ni(OH)2 and NiOOH array structure on vertical hanging Ni foam. Compared with traditional hydrothermal methods, vertical hanging Ni foam provide sufficient reaction sites and ensure fully growth of array structure, leading to large mass loading of active materials. The array structure and the wide interlayer spacing due to interlayer embedded CH3COO− together build an effcient ion diffusion path. Morevoer, strong electron exchange between Ni(OH)2 or NiOOH and Ni provide high electrical conductivity at the interface, forming the fast and complete electron transport channel inside the electrode. As a result of robust electrochemical kinetics, NiCoLDH@vNF-12 shows a high capacitive and outstanding rate performance of 952.9 C g−1 at 1 A g−1 and 660.0 C g−1 even at 50 A g−1.

In Situ Synthesis Method of Approaching High Surface Capacity Sulfur and the Role of Cobalt Sulfide as Lithium–Sulfur Battery Materials

Lithium–sulfur batteries (Li–S) are potentially applicable in electrification and the replacement of fossil fuels due to the high energy density and the economy of sulfur. However, effectively an insulator, sulfur is known to suffer from inert electrochemical and poor conductivity. By synthetically incorporating conductive, low‐dimensional carbonaceous composites acting as both containment hosts and catalysts to active materials, this work entails an effective and straightforward materials engineering approach in fundamentally remodeling active materials utilization and activation. This synthetic‐based approach highlights direct processing capabilities than traditional thermal infusion processes without compromising performance and addresses the low activation, poor conductivity as well as alleviating side reactions due to polysulfide species. Motivated by recent efforts in excellent catalytic properties of cobalt sulfide (CoS)‐based materials, in this work, high‐performance CoS‐based carbonaceous composites are designed and employed, alleviating side reactions. These sulfide‐based catalysts are further elucidated in their role in facilitating charge/discharge of active materials, and assessed on practical polysulfide and side reaction alleviation with respect to various discharge/charge states. Proof‐of‐concept devices demonstrate the following performance highlights: 1) high‐performance stability, 2) strong polysulfide adsorption capability and kinetic characteristics, 3) large and workable areal capacity, and active materials loading.

Laser-induced oxygen vacancy defect Mn7O13·5H2O as binder-free cathode for high performance all-in-one zinc-ion battery

Reachable Zinc ion batteries (ZIBs) are regarded as promising large scale energy storge systems because of their advantages of high safety, high energy density (high volumetric capacity), and economic benefits. However, ZIBs suffer from of lack of suitable cathode materials with high capacity and long stability of circulation. In addition, conventional coating process to prepare cathode with binder (PVDF/PTFE et al.) will not only reduce active material loading but also hinder ion transmission. Hence, a simple binder-free cathode prepare process was proposed. We use laser irradiation the Mn7O13·5H2O/graphene oxide cathode. The laser irradiation will induce vacancy defect in the Mn7O13·5H2O, leading to more active contact sites. Finally, the prepared materials achieve an ultra-high specific capacity of 411.6 mAh g−1 (0.2 A g−1), an excellent rate performance (176.3 mAh g−1 at a current density of 5 A g−1), and a satisfactory capacity retention rate of 90.1% after long 3500 cycles at 2 A g−1. The assembled all-in-one architecture battery has a fair specific capacity of 177.3 mAh g−1 at the current density of 2 A g−1. This work opens up a new horizon for conveniently preparing binder-free cathode materials with defects for high energy density and long cycle life.

A sulfur cathode design strategy for polysulfide restrictions and kinetic enhancements in Li-S batteries through oxidative chemical vapor deposition

Lithium-sulfur (Li-S) batteries offer a promising solution for achieving high-density and low-cost energy storage devices. However, the practical utilization of Li-S batteries is hindered by the main bottleneck of polysulfides transport from the cathode to the electrolyte and anode, which leads to the detrimental degradation of the electrolyte and non-uniform microstructure evolution on the anode, ultimately resulting in rapid capacity fading. To overcome this limitation, we propose a groundbreaking mitigation strategy that leverages the oxidative chemical vapor deposition (oCVD) technique to limit the shuttling of polysulfides in the cathode. This gas-phase approach is unique in that highly conducting and conformal polymer coating entirely eliminates the use of traditional binders in the cathode while enhancing the kinetic conditions of the sulfur conversion and inhibiting the shuttling of polysulfides during battery operation. Complementary experimental and theoretical investigations identify that polysulfides are physically and chemically confined in the cathode region. The sulfur cathode manufactured using this approach demonstrates high active material loading (90 wt%), a high sulfur utilization ratio of 84.4% (∼1413 mAh g−1 at 0.1 C), and capacity retention of 85% after 300 cycles (∼810 mAh g−1) at 0.5 C. The pouch cell also showcases a high specific energy of up to 202 Wh kg−1 with a low electrolyte/sulfur ratio of 4.55, proving the immense potential for practical applications.

3D hierarchical self-supporting Bi2Se3-based anode for high-performance lithium/sodium-ion batteries

Bi2Se3 is a promising material for anodes in lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs) due to its abundance, easy preparation, and high capacity. However, its practical application is hindered by low conductivity and significant volume variation during cycling, leading to poor rate capability and cycling stability. Herein, a novel composite consisting of Bi2Se3 nanoplates deposited on carbon cloth (CC) and encapsulated by reduced graphene oxide (rGO) has been designed and synthesized. The composite structure combines the advantages of the Bi2Se3 nanoplates, CC substrate, and rGO encapsulation, leading to enhanced electrochemical properties. The physical vapor deposition of Bi2Se3 nanoplates onto CC ensures a high loading of active material, while the rGO encapsulation provides a conductive and stable framework for the composite. This synergistic design allows for improved electron and ion transport, as well as efficient accommodation of the volume changes during cycling. In LIBs, the composite demonstrates a high reversible capacity of 467.5 mAh/g at 0.1 A/g after 120 cycles. Moreover, it displays an outstanding rate capability, delivering a capacity of 398.6 mAh/g at 5.0 A/g. Similarly, in SIBs, the composite maintains a reversible capacity of 375.3 mAh/g at 0.1 A/g over 100 cycles and exhibits a high-rate capacity of 286.3 mAh/g at 5.0 A/g. This work represents a significant step forward in addressing the challenges associated with Bi2Se3 as an anode material, paving the way for the development of high-performance LIBs and SIBs.

Electrochemical activation strategy enabled ammonium vanadate cathodes for all-climate zinc-ion batteries

Aqueous zinc-ion batteries (ZIBs) have attracted significant attention for grid-scale energy applications due to their low cost, intrinsic safety, and environmental friendliness. However, the energy density of current ZIBs is impeded by unsatisfactory performance of cathodes, due to their limited areal capacity and low active material loading, especially at extreme environments. Herein, an electrochemical activation strategy is put forward to build high energy density ZIBs by designing a flexible cathode composed of NH4+ pillared ammonium vanadate nanosheets on carbon cloth (NVMCE@CC). The electrochemical activation process with high anodic potential (> 1.5 V vs. Zn2+/Zn) guarantees the effective conversion of low-valent to high-valent vanadium and promotes the utilization of large amounts of vanadium elements in the NVMCE@CC composite. Meanwhile, the pillared NH4+ ions expand the interlayer spacing and enhance the structural integrity through the hydrogen bonding between NH4+ and V-O framework. Consequently, the activated NVMCE@CC cathode with a high mass-loading of ∼5.2 mg cm−2 delivers large areal capacity (∼1.74 mAh cm−2 at 1 mA cm−2) and superior cycling stability (capacity retention of 72.1% after 1500 cycles). Importantly, the flexible cathode shows admirable capacities of 0.52 mAh cm−2 at 60 °C and 0.55 mAh cm−2 at − 10 °C, respectively. Moreover, the NVMCE@CC//Zn@CC quasi-solid-state battery demonstrates excellent safety performance and performs well in extreme situations, including bending, cutting, hammering, and washing. This work provides enlightenment for the development of large-areal-capacity vanadium-based cathode materials for practical ZIBs.

Great truths are always simple: Preoxidation-tuned cellulose-derived carbon fibers achieving ultrahigh areal desalination capacity in flow-through capacitive deionization

Constructing thick electrodes with both high strength and porous characteristics is challenging but critical to improve the desalination performance of flow-through capacitive deionization (FTCDI). Different from the most reported electrodes composed of carbon nanomaterials, micron-sized carbon fibers are more advantageous due to the innate excellent mechanical stability and macroscopic porous fibrous structure. Herein, we reported the preoxidation-tuned cellulose-derived carbon fibers (POCF) with improved specific surface area, pore volume, hydrophilicity, and carbon defect degree by precisely-controlled preoxidation process, resulting in enhanced electrochemical activity and sites. Further studies of the cellulose pyrolysis mechanism disclose that preoxidation temperature has a crucial influence on the carbon yield and electrical conductivity, which significantly affect the desalination capacity of the integrated (current collector-free and binder-free) POCF electrode. Compared with the conventional activated carbon-coated electrode and commercial activated carbon fibers cloth electrode, the POCF electrode exhibits outstanding desalination performance due to the synergistic effect of high active materials loading and good electrical conductivity. Most importantly, the desalination capacity of POCF electrode realizes the linear growth with 4-fold enhancement by increasing the thickness and remains almost unchanged even up to a large size of 120 cm2, indicating unlimited ion diffusion and excellent scalability. Impressively, an ultrahigh areal salt ion adsorption capacity of 0.76 mg cm−2 is achieved for the 2.4 mm thick POCF electrode. Our work successfully validates the feasibility and superiority of the POCF in constructing thick electrodes for achieving high areal desalination performance.

Bottom growth strategy for high areal capacity rechargeable aluminum batteries

Among all practical methods to build the high specific energy battery, increasing the areal loading of active materials is a promising choice. However, increasing the areal loading of the active material will inevitably increase the areal deposition amount of aluminum. If aluminum undergoes uneven deposition, dendrite growth is an inevitable problem with the increase of aluminum deposits. In this paper, an anode structure with bottom growth mode (2P-Al2O3/Al) are proposed through anodic oxidation and laser etching technology, which can provide an inverted electric field strength (Ebottom>Etop) to induce the directional deposition of Al. We have grown a dense alumina layer on the surface and pores of the 2P-Al2O3/Al electrode, which can form a stable electrode/electrolyte interface as an SEI layer. The in-situ deposition image of the electrode indicates that aluminum preferentially grows at the bottom of the electrode, and the deposition process of aluminum is very uniform. In addition, the electrode exhibits excellent cycling stability in both half and full batteries. Even under the large areal special capacity of 20 mAh·cm−2 without presenting significant interfacial degradation and early short circuit, it can operate cycle over 900 h, which is more than 3 times that of planer aluminum anode. This technology opens a new platform for designing highly safe and stable long-term energy storage system.

Enhancing the Electrode Gravimetric Capacity of Li1.2Mn0.4Ti0.4O2 Cathode Using Interfacial Carbon Deposition and Carbon Nanotube-Mediated Electrical Percolation.

Mn-based cation-disordered rocksalt oxides (Mn-DRX) are emerging as promising cathode materials for next-generation Li-ion batteries due to their high specific capacities and cobalt- and nickel-free characteristic. However, to reach the usable capacity, solid-state synthesized Mn-DRX materials require activation via postsynthetic ball milling, typically incorporating more than 20 wt % conductive carbon that adversely reduces the electrode-level gravimetric capacity. To address this issue, we first deposit amorphous carbon on the surface of the Li1.2Mn0.4Ti0.4O2 (LMTO) particles to increase the electrical conductivity by 5 orders of magnitude. Although the cathode material gravimetric first charge capacity reaches 180 mAh/g, its highly irreversible behavior leads to a first discharge capacity of 70 mAh/g. Subsequently, to ensure a good electrical percolation network, the LMTO material is ball-milled with a multiwall carbon nanotube (CNT) to obtain a 78.7 wt % LMTO active material loading in the cathode electrode (LMTO-CNT). As a result, a 210 mAh/g cathode electrode gravimetric first charge and 165 mAh/g first discharge capacity values are obtained, compared to the respective capacity values of 222 and 155 mAh/g for the LMTO material ball-milled with 20 wt % SuperP C65 electrode (LMTO-SP). After 50 cycles, LMTO-CNT delivers a 121 mAh/g electrode gravimetric discharge capacity, largely outperforming the value of 44 mAh/g of LMTO-SP. Our study demonstrates that while ball milling is necessary to achieve a significant amount of capacity of LMTO, a careful selection of additives, such as CNT, effectively reduces the required carbon quantity to achieve a higher electrode gravimetric discharge capacity.

Hybridization of graphene into NiCo2S4 hybrid composites as electrode materials for high performance supercapacitors

NiCo2S4 is one of the most promising bimetallic sulfides for use in energy-storage systems, but more studies are needed to endow NiCo2S4 (NCS) with a high electrochemical reaction capability and reversibility. In this work, we present rationally materials design of an optimal NiCo2S4 nanoparticle in a graphene (G) matrix as a NiCo2S4/graphene nanocomposite (NCSG). A uniform composite with NiCo2S4 nanoparticles anchored on graphene sheets is fabricated through an innovative one-step hydrothermal method. The XRD, Raman, XPS, SEM, HRTEM and EDS analyses are performed for characterizing the morphology and microstructure of the as-prepared NiCo2S4/graphene composite. Furthermore, we report the improvements in the materials technology, demonstrating the NiCo2S4/graphene (NCSG) nanocomposite electrode with an excellent specific capacitance of 1500 Fg−1 at 2 Ag−1, high capacitance retention of 85.6 %, and long cycle life of 6500 cycles. The practical application is showcased in an asymmetric supercapacitor with a high active-material loading. Tremendously, the produced NiCo2S4/AC asymmetric supercapacitor has a high energy density of 43.2 Wh kg−1 at a power density of 920 W kg−1.

Solar‐Driven CO2 Conversion via Optimized Photothermal Catalysis in a Lotus Pod Structure

AbstractPhotothermal CO2 reduction is one of the most promising routes to efficiently utilize solar energy for fuel production at high rates. However, this reaction is currently limited by underdeveloped catalysts with low photothermal conversion efficiency, insufficient exposure of active sites, low active material loading, and high material cost. Herein, we report a potassium‐modified carbon‐supported cobalt (K+−Co−C) catalyst mimicking the structure of a lotus pod that addresses these challenges. As a result of the designed lotus‐pod structure which features an efficient photothermal C substrate with hierarchical pores, an intimate Co/C interface with covalent bonding, and exposed Co catalytic sites with optimized CO binding strength, the K+−Co−C catalyst shows a record‐high photothermal CO2 hydrogenation rate of 758 mmol gcat−1 h−1 (2871 mmol gCo−1 h−1) with a 99.8 % selectivity for CO, three orders of magnitude higher than typical photochemical CO2 reduction reactions. We further demonstrate with this catalyst effective CO2 conversion under natural sunlight one hour before sunset during the winter season, putting forward an important step towards practical solar fuel production.

Solar-Driven CO2 Conversion via Optimized Photothermal Catalysis in a Lotus Pod Structure.

Photothermal CO2 reduction is one of the most promising routes to efficiently utilize solar energy for fuel production at high rates. However, this reaction is currently limited by underdeveloped catalysts with low photothermal conversion efficiency, insufficient exposure of active sites, low active material loading, and high material cost. Herein, we report a potassium-modified carbon-supported cobalt (K+ -Co-C) catalyst mimicking the structure of a lotus pod that addresses these challenges. As a result of the designed lotus-pod structure which features an efficient photothermal C substrate with hierarchical pores, an intimate Co/C interface with covalent bonding, and exposed Co catalytic sites with optimized CO binding strength, the K+ -Co-C catalyst shows a record-high photothermal CO2 hydrogenation rate of 758 mmol gcat -1 h-1 (2871 mmol gCo -1 h-1 ) with a 99.8 % selectivity for CO, three orders of magnitude higher than typical photochemical CO2 reduction reactions. We further demonstrate with this catalyst effective CO2 conversion under natural sunlight one hour before sunset during the winter season, putting forward an important step towards practical solar fuel production.

Development of carbon materials for sulfur cathodes in inorganic-based solid-state lithium–sulfur batteries

Inorganic-based solid-state lithium–sulfur batteries (SSLSBs) with high energy density and high safety have attracted wide attention as they are one of the most promising energy storage devices to meet future market requirements. However, the development of SSLSBs faces various challenges due to the unreasonable structural design in sulfur cathodes. Carbon is one of the indispensable components in sulfur cathodes. The rational design of carbon materials becomes an important strategy to address the challenges in sulfur cathodes. This review summarizes recent literature about the design and application of carbon materials for sulfur cathodes in inorganic-based SSLSBs. It starts with the introduction of different carbon materials from zero-dimensional to three-dimensional carbon materials. Particularly, this review paper highlights the structural design of carbon materials and the cathode fabrication methods, toward improving the conductivity of cathodes, buffering volume changes in cathodes, reducing interfacial resistance among cathode components, and increasing the mass loading of active materials. Finally, the existing challenges and promising solutions for carbon materials in the cathodes are discussed and proposed.