High Areal Mass Loading Research Articles

A novel cathode interphase formation methodology by preferential adsorption of a borate-based electrolyte additive.

The coupling of high-capacity cathodes and lithium metal anodes promises to be the next generation of high-energy-density batteries. However, the fast-structural degradations of the cathode and anode challenge their practical application. Herein, we synthesize an electrolyte additive, tris(2,2,3,3,3-pentafluoropropyl) borane (TPFPB), for ultra-stable lithium (Li) metal||Ni-rich layered oxide batteries. It can be preferentially adsorbed on the cathode surface to form a stable (B and F)-rich cathode electrolyte interface film, which greatly suppresses the electrolyte-cathode side reactions and improves the stability of the cathode. In addition, the electrophilicity of B atoms in TPFPB enhances the solubility of LiNO3 by 30 times in ester electrolyte to significantly improve the stability of the Li metal anode. Thus, the Li||Ni-rich layered oxide full batteries using TPFPB show high stability and an ultralong cycle life (up to 1500 cycles), which also present excellent performance even under high voltage (4.8V), high areal mass loading (30mg cm-2) and wide temperature range (-30∼60°C). The Li||LiNi0.9Co0.05Mn0.05O2 (NCM90) pouch cell using TPFPB with a capacity of 3.1Ah reaches a high energy density of 420Wh kg-1 at 0.1C and presents outstanding cycling performance.

CeO2/Co heterostructure encapsulated in hollow necklace-like carbon fiber as an advanced host material for high-performance lithium-sulfur batteries

The shuttle effect of lithium polysulfides (LiPSs) and the sluggish reaction kinetics of LiPSs conversion pose serious challenges to the commercial feasibility of lithium-sulfur (Li-S) batteries. To address these obstacles, herein, we construct CeO2/Co heterostructures in hollow necklace-like carbon fibers (CeO2/Co-CNFs) as the cathode host material for Li-S batteries. The specific surface area of fibers is significantly enhanced by using a template, thereby promoting the utilization efficiency of sulfur. Meanwhile, CeO2/Co-CNFs show strong conductivity, effective adsorption to LiPSs, and robust catalytic activity for LiPSs conversion. As a result, the Li-S battery with CeO2/Co-CNFs displays 961 mAh g−1 at 0.2 C, with an 86 % capacity retention rate after 100 cycles. At 2.0 C current density, the composite cathode maintains an initial discharge capacity of 782 mAh g−1, with a mere 0.044 % capacity loss per cycle. Furthermore, in situations with limited electrolytes, high sulfur loading, and high areal mass loading, the composite cathode can provide a high areal capacity of 6.2 mg cm−2 over 100 cycles. This work provides a useful approach for investigating high-performance Li-S battery cathodes.

Striking a Balance: Exploring Optimal Functionalities and Composition of Highly Adhesive and Dispersing Binders for High‐Nickel Cathodes in Lithium‐Ion Batteries

AbstractNickel‐rich layered oxide, LiNixCoyMnzO2 (NCM, x > 0.8), has emerged as a promising cathode material for lithium‐ion batteries due to its high specific capacity and energy density. However, there remains a challenge regarding NCM degradation during cycling, associated with interfacial side reactions and microcrack formation. Herein, a functional poly(norbornene‐co‐norbornene dicarboxylic acid‐co‐heptafluorobutyl norbornene imide) (PNCI)‐based binder system is introduced, with controlled functionalities and monomer compositions, to preserve the structural integrity of NCM. The PNCI binder system incorporates three different norbornene‐derived monomers with distinct functionalities, allowing for multifunctionality, including electro‐chemo‐mechanical stability, strong adhesion, and dispersibility. By systematically adjusting the molar composition of the PNCI binders, the overall binder characteristics are fine‐tuned, optimizing the adhesion and dispersion of electrode components. The optimized PNCI binder, with desired adhesion strength, surface energy, and polarity, plays a crucial role in facilitating the formation of a uniform electrode structure with a high areal mass loading of NCM, ensuring long‐term cycling stability. This study highlights the significance of striking a balance between functionalities and composition in binder systems to achieve high‐performance NCM cathodes.

A 3D-Printed Proton Pseudocapacitor with Ultrahigh Mass Loading and Areal Energy Density for Fast Energy Storage at Low Temperature.

The sluggish ionic transport in thick electrodes and freezing electrolytes has limited electrochemical energy storage devices in lots of harsh environments for practical applications. Here, a 3D-printed proton pseudocapacitor based on high-mass-loading 3D-printed WO3 anodes, Prussian blue analog cathodes, and anti-freezing electrolytes is developed, which can achieve state-of-the-art electrochemical performance at low temperatures. Benefiting from the cross-scale 3D electrode structure using a 3D printing direct ink writing technique, the 3D-printed cathode realizes an ultrahigh areal capacitance of 7.39Fcm-2 at a high areal mass loading of 23.51mgcm-2 . Moreover, the 3D-printed pseudocapacitor delivers an areal capacitance of 3.44 Fcm-2 and excellent areal energy density (1.08 mWhcm-2 ). Owing to the fast ion kinetics in 3D electrodes and the high ionic conductivity of the hybrid electrolyte, the 3D-printed supercapacitor delivers 61.3% of the room-temperature capacitance even at -60°C. This work provides an effective strategy for the practical applications of energy storage devices with complex physical structure at extreme temperatures.

Wide‐Temperature, Long‐Cycling, and High‐Loading Pyrite All‐Solid‐State Batteries Enabled by Argyrodite Thioarsenate Superionic Conductor

AbstractRechargeable FeS2 battery has been regarded as a promising energy storage device, due to its potentially high energy density and ultralow cost. However, the short lifespan associated with the shuttle effect of polysulfides, large volume change, agglomeration of Fe0 nanoparticles, narrow operating temperature range, and sluggish reaction kinetics, greatly impede the application of rechargeable FeS2 lithium‐ion batteries. Herein, an all‐solid‐state battery (ASSB) coupling commercialized FeS2 is proposed with a novel superionic conductor Li6.8Si0.8As0.2S5I (LASI‐80Si) to overcome these challenges. The shuttle effect of polysulfides and volume change of FeS2 are suppressed or completely eliminated in ASSB, due to solid‐solid conversion of Li2S/S and large stacking pressure, respectively. Furthermore, the operating temperature range (−60–60 °C) is significantly expanded by the ultra‐high and temperature‐insensitive ionic conductivity of LASI‐80Si (Ea = 0.20 eV), along with the superior FeS2/LASI‐80Si interface stability. Thanks to the extra Li+ provided by Li2S and LiI functional phases, the “bridge” effect of LiI on facile interfacial Li‐ion conduction, and the enhanced reaction kinetics of LASI‐80Si ( 10.4 mS cm−1), ASSBs with LASI‐80Si deliver long cycle life (244 cycles at 0.1 C and 600 cycles at 1 C), superior rate capability (20 C), high areal mass loading (13.37 mg cm−2), and ultrahigh areal capacity (9.05 mAh cm−2). These inspiring results demonstrate the enormous potential of LASI‐80Si and FeS2 combination for practical application of wide‐temperature and large‐capacity ASSBs.

Achieving Sustainable and Stable Potassium-Ion Batteries by Leaf-Bioinspired Nanofluidic Flow.

In nature, living systems have evolved integrated structures, matching optimized nanofluidics to adapt to external conditions. In rechargeable batteries, high-capacity electrodes are often plagued by the crucial and universal bottleneck of dissolution and shuttle of active substance into electrolyte, posing obstacles of inevitable capacity degradation. Introducing the concept of intelligent nanofluidics to electrodes, a leaf-bioinspired electrode configuration with hierarchical architecture to tackle this problem is proposed. This integrated structure with fine-tuned surface pores and unobstructed interior porous media, can spatially control the anisotropic nanofluidic flux, in an efficient and self-protectable way: tailoring the outflow across the electrode's surface and free transport in interior, to ensure speedy and stable energy conversion. As proofs of concept, applications of sustainable electrodes rejuvenated from fallen leaf and spent commercial batteries, are designed with leaf-bioinspired architecture. Both KCoS2 and KS battery systems show advanced steady cycling with effectively mitigated shuttle issues in this smart architecture (0.15% and 0.21% capacity decay per cycle), even at high areal mass loading, when compared with open porous structure (0.60% and 0.39%). This work may pave a new way from a biomimetic view to integrated electrode engineering with regulated surface shielding to conquer the universal dissolution-shuttle problems facing high-capacity materials.

Preparation of carbon nanotubes‐hollow Co 9 S 8 composite and its use in separator modification for lithium‐sulfur battery

Lithium-sulfur batteries (LSBs) have received numerous studies because of their advantages of high specific capacity, low cost of the sulfur element and so on. However, there are several obstacles restricting the commercial use of LSBs, including low conductance of sulfur, volume expansion effect of the positive sulfur electrode and serious shuttle effect of soluble lithium polysulfides. In this work, a composite of carbon nanotubes (CNTs) and hollow Co9S8 (CNTs/Co9S8) is synthesized via ZIF-67 as a template and is applied on the surface of the PE separator for LSBs. Benefited from the excellent conductance of CNTs as well as the adsorption and catalysis properties of polar hollow Co9S8, the cell with the CNTs/Co9S8 composite functional separator delivered the discharge capacity of 977.6 and remained 456 mAh g−1 after 500 loops at a current density of 0.5 C, corresponding to a low attenuation rate of only 0.1% per cycle, as well as excellent rate properties. Even at high areal mass loading of active sulfur, LSBs exhibited excellent long-term cycling stability at various current rates. In addition, the Li dendrites were remarkably restrained, which further enhanced the safety of batteries. This paper provides an effective and newfangled approach with modified separators coating composite materials of carbon species and structural sulfide to inhibit the shuttle of intermediate polysulfides and further enhance the utility of LSBs in the future.

Micrometer-Sized SiMgy Ox with Stable Internal Structure Evolution for High-Performance Li-Ion Battery Anodes.

In recent years, micrometer-sized Si-based anode materials have attracted intensive attention in the pursuit of energy-storage systems with high energy and low cost. However, the significant volume variation during repeated electrochemical (de)alloying processes will seriously damage the bulk structure of SiOx microparticles, resulting in rapid performance fade. This work proposes to address the challenge by preparing in situ magnesium-doped SiOx (SiMgy Ox ) microparticles with stable structural evolution against Li uptake/release. The homogeneous distribution of magnesium silicate in SiMgy Ox contributes to building a bonding network inside the particle so that it raises the modulus of lithiated state and restrains the internal cracks due to electrochemical agglomeration of nano-Si. The prepared micrometer-sized SiMgy Ox anode shows high reversible capacities, stable cycling performance, and low electrode expansion at high areal mass loading. A 21700 cylindrical-type cell based on the SiMgy Ox -graphite anode and LiNi0.8 Co0.15 Al0.05 O2 cathode demonstrates a 1000-cycle operation life using industry-recognized electrochemical test procedures, which meets the practical storage requirements for consumer electronics and electric vehicles. This work provides insights on the reasonable structural design of micrometer-sized alloying anode materials toward realization of high-performance Li-ion batteries.

Achieving ion accessibility within graphene films by carbon nanofiber intercalation for high mass loading electrodes in supercapacitors

Achieving high specific surface area and ion accessibility in graphene-based electrodes with a high mass loading for supercapacitors poses a significant challenge because strong π-π stacking of graphene sheets often blocks the access of electrolyte ions to active sites. Herein, we report a novel protocol to prepare free-standing laminated graphene/carbon nanofiber films as high areal mass-loading electrodes through a layer-by-layer electrospinning technique. The unique laminated structure of graphene/carbon nanofiber thin films can enhance electrolyte penetration and increase transportations of ions/electrons. The symmetric supercapacitors (SCs) using the as-obtained graphene/carbon nanofiber films as electrodes reach areal specific capacitance of 1536 mF cm−2 at a current density of 1 mA cm−2. Most importantly, the areal energy density of the SCs can reach 0.22 mWh cm−2 at a power density of 1 mW cm−2 with a high areal mass loading of 24 mg cm−2. The exceptional electrochemical properties of the laminated graphene/carbon nanofiber films render them promising materials for electrodes in SCs.

Wood-Derived, Conductivity and Hierarchical Pore Integrated Thick Electrode Enabling High Areal/Volumetric Energy Density for Hybrid Capacitors.

For the proliferation of the supercapacitor technology, it is essential to attain superior areal and volumetric performance. Nevertheless, maintaining stable areal/volumetric capacitance and rate capability, especially for thick electrodes, remains a fundamental challenge. Here, for the first time, a rationally designed porous monolithic electrode is reported with high thickness of 800 µm (46.74mg cm-2 , with high areal mass loading of NiCo2 S4 6.9mg cm-2 ) in which redox-active Ag nanoparticles and NiCo2 S4 nanosheets are sequentially decorated on highly conductive wood-derived carbon (WC) substrates. The hierarchically assembled WC@Ag@NiCo2 S4 electrode exhibits outstanding areal capacitance of 6.09 F cm-2 and long-term stability of 84.5% up to 10 000 cycles, as well as exceptional rate capability at 50mA cm-2 . The asymmetric cell with an anode of WC@Ag and a cathode of WC@Ag@NiCo2 S4 delivers areal/volumetric energy density of 0.59 mWh cm-2 /3.93 mWh cm-3 , which is much-improved performance compared to those of most reported thick electrodes at the same scale. Theoretical calculations verify that the enhanced performance could be attributed to the decreased adsorption energy of OH- and the down-shifted d-band of Ag atoms, which can accelerate the electron transport and ion transfer.

Constructing a Highly Efficient Aligned Conductive Network to Facilitate Depolarized High‐Areal‐Capacity Electrodes in Li‐Ion Batteries

AbstractIn order to prepare electrodes with high mass loading and areal capacities, the key issue is to achieve depolarization for both ion and electron transfer on the electrode material surface. In this work, through copolymerization of xanthan gum (XG) and amorphophallus konjac gum (KG) followed by an ice‐templating method, aligned electrodes with high areal mass loading of active materials are prepared. In addition to firmly holding active materials together, the prepared KG–XG copolymer also facilitates improved effective porosity as well as homogeneous dispersion of conductive agents (i.e., CNTs). Consequently, with minimum inactive components (i.e., binder and conductive agents), the proposed electrode structure delivers good cycling stability and rate capability under high areal loading (as high as 200 mg cm−2). The excellent electrochemical performance can be attributed to the unique aligned structure where the robust conductive network provides an efficient electron and lithium‐ion pathway, and the homogenous porosity is beneficial for the electrolyte percolation, hence the reduced polarization during charge transfer. In addition, this electrode preparation method is found to be universal as it is suitable for various types of anode and cathode materials.

Hollow carbon nanocages toward long cycle lifespan lithium/sodium-ion half/full batteries

• The structure of HCN can be controlled by the carbonization temperature. • HCN-800 shows an ultra-long cycle life and excellent electrochemical performance. • Achieved high areal mass loading through 3D printing technology. • LiCo 2 O 4 ||HCN-800 and Na 3 V 2 (PO 4 ) 3 ||HCN-800 full cells exhibits a stable cycle. Hollow nanostructures have shown great potential in energy storage and have attracted widespread attention. Here, we report a series of hollow carbon nanocage (HCN) by carbonizing ZIF-8@ZIF-67 core–shell precursor at different temperatures. The study found that when the carbonization temperature is 800 °C, HCN-800 has a good hollow structure, thin shell and large specific surface area, and contains abundant micropores and mesopores. When used as an anode material, even at a current density of 10.0 A g −1 , it can still obtain reversible capacities of 236.1 mA h g −1 (5000 cycles, lithium ion batteries LIBs) and 111.7 mA h g −1 (10000 cycles, sodium ion batteries SIBs), showing excellent cycle stability and long cycle lifespan. And this outstanding ability can still be maintained under high areal mass loading. In addition, the lithium/sodium storage behavior was analyzed by CV kinetic analysis, ex-situ XPS and Raman tests. Benefiting from these advantages, HCN-800 can be prepared with higher areal mass loading by 3D printing and exhibit excellent lithium/sodium storage performance, which will bring broad application prospects for the development of high energy density secondary batteries. Finally, by using LiCoO 2 /Na 3 V 2 (PO 4 ) 3 cathode and HCN-800 anode to assemble a full cell to study the cycle performance. After 100 cycles at 0.1 A g −1 current density, the reversible capacity of 561.5 mA h g −1 (LIBs) and 164.7 mA h g −1 (SIBs) can be provided respectively, indicates that it has the potential of practical application.

A novel fabricated conductive substrate for enhancing the mass loading of NiCoLDH nanosheets for high areal specific capacity in hybrid supercapacitors

Nickel foam (NF), as an excellent conductive substrate, is usually applied to the preparation of electrodes. However, the surface of nickel foam is too smooth to increase the loading of active materials. In this work, a facile method is developed to improve the mass loading of NiCo-layered double hydroxide nanosheets (NiCoLDH NSs) by directly vulcanizing nickel foam. The Ni3S2 nanocone formed on the surface of nickel foam (Ni3S2@NF) is characterized by XRD, XPS and SEM. The obtained NiCoLDH@Ni3S2@NF-480 using Ni3S2@NF as substrate possesses high NiCoLDH areal mass loading of 4.0 mg cm−2, which is far above that of NiCoLDH@NF-480 using pure NF as substrate (0.2 mg cm−2). Accordingly, the NiCoLDH@Ni3S2@NF-480 electrode displays a high specific capacity of 2.021 C cm−2 under the current density of 1 mA cm−2. It also presents excellent cycling stability with 92% of capacity retention after 5000 times cycles. The hybrid asymmetric supercapacitor (NiCoLDH@Ni3S2@NF-480//nitrogen-doped mesoporous carbon) exhibits a high volumetric energy density of 0.52 mW h cm−3 and high power density of 32 mW cm−3. This work may provide a new substrate for fabricating the high mass loading electrode in energy storage device.

Engineering the defects of Co3O4-x bubbles in lotus root-like multichannel nanofibers to realize superior performance and high durability for fiber-shaped hybrid Zn battery

Herein, a lotus root-like nanofibers composed of Co3O4-x bubbles (MCB) with engineered defects is introduced as a novel cathode for hybrid Zn battery (HZB). The nanoscale Co3O4-x bubbles with tailored defects are encapsulated by porous carbon matrix and construct the lotus root-like multichannel structure. The porous and conductive carbon based substrate enables the fast electron/ion transport and facilitates highly reversible redox reaction. In addition, the engineered defects of Co3O4-x bubbles and the multichannels inside the nanofiber provide abundant active sites and ensure the high bifunctional activities towards oxygen evolution/reduction (OER/ORR) reactions. Meanwhile, the good mechanical characteristics and unique structure enable it a good flexible electrode with high areal mass loading and superior electrochemical properties. Accordingly, the MCB nanofiber is a highly efficient platform to synergistically achieve fast kinetics, high energy/power density and excellent durability. For the first time, the formation mechanism of the MCB nanofiber is probed. The relationship between the oxygen vacancies regulated by Kirkendall effect and the electrochemical performance of the electrode is clarified. Moreover, the fabricated fiber-shaped HZB achieves high energy density, superior high-rate capability and long-term cycling stability. Even after high-rate and long-term cycling, it still retains the characteristic two-set charge/discharge profiles and high energy efficiency. More impressively, it exhibits high durability in different outside deformation, working environments or even during working condition transitions.

Groundnut shell–derived porous carbon-based supercapacitor with high areal mass loading using carbon cloth as current collector

The present study demonstrates fabrication, characterization, and electrochemical performances of bio-waste-based groundnut shell–derived activated porous carbon as supercapacitor electrodes by using carbon cloth as a current collector with high-level mass loading of 9–10 mg cm−2. The higher mass loading on the electrode is mainly attributed to interconnected porous network of carbon cloth, which helps to accommodate more active materials per unit volume as compared with that of other metallic current collectors. The obtained activated porous carbon possesses a very high specific surface area of 1700 m2 g−1 and a total pore volume of 0.82 cm3 g−1. The electrochemical performances of the supercapacitor electrodes are systematically investigated by using two different aqueous electrolytes such as 6 M KOH and 0.5 M Na2SO4 in two-electrode systems. The obtained results revealed that the supercapacitor electrodes exhibited a higher energy density of about 16.92 Wh kg−1 in 0.5 M Na2SO4 as compared with 6 M KOH electrolyte due to its low potential window of 1 V. Furthermore, the electrode is having more advantages like high packing density (0.73 g cm−3) and high volumetric performances with long durability. It is also found that the supercapacitor exhibits excellent durability upon 12,000 charge-discharge cycles with 99% of capacitance retention and also 99% of Coulombic efficiency. This study unveils an eco-friendly, cost-effective, and facile route to fabricate the activated porous carbon, and it is explored as a potential electrode for high volumetric supercapacitor applications.

3D printed cellular cathodes with hierarchical pores and high mass loading for Li–SeS2 battery

To satisfy the vast demand on high energy density for the next-generation electrochemical energy storage system, lithium selenium-sulfur (Li-SexSy) battery has drawn ever-growing interest with great advantages of low cost and promising capacity. However, its practical application with high areal mass loading of electrode manufacturing is still challenging. Here, we firstly print three-dimensional (3D) freestanding electrodes for Li–SeS2 batteries via direct ink writing based on the high-solid-content ink. The characteristic rheology properties of the ink possess excellent printability and enable the stable extrusion of 3D-printed cellular scaffold. In such a printed architecture, the low-cost commercial conducting ketjenblack (KB) with abundant pores is selected as the host material for selenium sulfide. For a well-controlled 3D-printed KB/SeS2 electrode, the areal SeS2 loading reaches 7.9 mg cm−2. More importantly, with the hierarchical porosity engineering, the 3D-printed cellular KB/SeS2 cathode delivers a high initial discharge capacity of 9.5 mA h cm−2 at 1.8 mA cm−2 and high Coulombic efficiency of 96% over 80 cycles is achieved with such high mass loading. This 3D-printed Li–SeS2 battery electrode may guide more energy storage systems with ultrahigh capacity to the practical application.

Single atomic cobalt catalyst significantly accelerates lithium ion diffusion in high mass loading Li2S cathode

It is widely accepted that catalysts in batteries can decrease the energy barriers of conversion reactions. However, little attention has been paid to their influence on ionic diffusion in the electrode or across the interface. Herein, we report that lithium ion diffusivity can be significantly accelerated in an intrinsically electrode by atomically-distributed metal catalyst. Electrochemical measurements have found single atomic cobalt catalyst embedded in a nanocarbon network is capable of increasing the kinetics of lithium ion, providing rapid conversion reaction rate in an ultrahigh-rate Li2S battery. Meanwhile, density functional theory simulations have revealed that the lithium ion diffusion barrier on a nanocarbon surface is highly sensitive to the dopant atoms and can be decreased by introduction of cobalt atoms. The synergetic effects of the well-known Li2S decomposition catalysis and the lithium ion diffusion acceleration allow us to achieve a high Li2S mass loading cathode with superior rate performance and reversibility. The as-prepared Li2S electrode converted from cheap Li2SO4 precursors can deliver a high rate capacity (441 ​mA ​h ​g-1 based on Li2S at 10 ​C) and long lifespan for 1500 cycles at 2 ​C with average capacity fading of 0.04% per cycle. Impressively, the high areal mass loading cells display a specific capacity of 340 ​mA ​h ​g-1 based on Li2S mass at 23.4 ​mA ​cm-2 (5 ​C) and a long cycle life (2.26 ​mA ​h ​cm-2 at 6.77 ​mA ​cm-2 after 200 cycles), which have not been reported for Li2S cathodes.

Uniformly Confined Germanium Quantum Dots in 3D Ordered Porous Carbon Framework for High‐Performance Li‐ion Battery

AbstractAlthough abundant germanium (Ge)‐based anode materials have been explored to obtain high specific capacity, high rate performance, and long charge/discharge lifespans for lithium‐ion batteries (LIBs), their performances are still far from satisfactory due to the intrinsic defects of Ge and the relatively intricate anode structure. To work out these issues, a 3D ordered porous N‐doped carbon framework with Ge quantum dots uniformly embedded (3DOP Ge@NC) as a binder‐free anode for LIBs via a facile polystyrene colloidal nanospheres template‐confined strategy is proposed. This unique structure not only facilitates Li‐ion diffusion and electron transport that can guarantee rapid de/alloying reaction, but also alleviates the huge volume changes during reactions and improves cycling stability. Notably, the resulting anode delivers a high specific reversible capacity (≈1160 mA h g−1 at 1 A g−1), superior rate properties (exceeding 500 mA h g−1 at 40 A g−1), and excellent cycling stability (over 90% capacity retention after 1200 cycles even at 5 A g−1). Furthermore, both the 3DOP Ge@NC anode with high areal mass loading (up to 8 mg cm−2) and the full cell coupled with LiFePO4 cathode display high capacity and cycling stability, further indicative of the favorable real‐life application prospects for high‐energy LIBs.

Nano-carbon-fiber-penetrated sulfur crystals as potential cathode active material for high-performance lithium–sulfur batteries

A novel composite consisting of vapor-grown carbon fibers penetrating sulfur crystals is developed. Using this new composite as the cathode active material greatly improves the ionic and electronic conductivity of fabricated lithium–sulfur batteries and helps to suppress the polarization of S intermediates during the charging and discharging processes. Importantly, the special structure of the composite also offers the potential of freely achieving high areal mass loading and capacity via the cost-efficient tape-casting method. The constructed battery exhibits a highly stable capacity of 920 mA h g−1 at 0.1C with good retention of 90% after 200 charge–discharge cycles and a good coulombic efficiency of 100%. Furthermore, good areal capacities of 3.4–4.4 mAh cm−2 with retention of 93–97% through cycles under 0.2–0.5C are achieved. These good performances are attributed to the greatly improved conductivity of the sulfur electrode, better utilization of sulfur, and the lower dissolution and shuttle effect of the polysulfides in the cell.

Scalable Solution Processing MoS2 Powders with Liquid Crystalline Graphene Oxide for Flexible Freestanding Films with High Areal Lithium Storage Capacity.

Freestanding flexible electrodes with high areal mass loading are required for the development of flexible high-performance lithium-ion batteries (LIBs). Currently they face the challenge of low mass loading due to the limited concentrations attainable in processable dispersions. Here, we report a simple low-temperature hydrothermal route to fabricate flexible layered molybdenum disulfide (MoS2)/reduced graphene oxide (MSG) films offering high areal capacity and good lithium storage performance. This is achieved using a self-assembly process facilitated by the use of liquid crystalline graphene oxide (LCGO) and commercial MoS2 powders at a low temperature of 70 °C. The amphiphilic properties of ultralarge LCGO nanosheets facilitates the processability of large-size MoS2 powders, which is otherwise nondispersible in water. The resultant film with an areal mass of 8.2 mg cm-2 delivers a high areal capacity of 5.80 mAh cm-2 (706 mAh g-1) at 0.1 A g-1. This simple method can be adapted to similar nondispersible commercial battery materials for films fabrication or production of more complicated constructs via advanced fabrication technologies.