Flexible Lithium-sulfur Batteries Research Articles

Roller-like Spore Carbon Sphere-Orientated Graphene Fibers Prepared via Rheological Engineering for Lithium Sulfur Batteries.

Flexible batteries with large energy densities, lightweight nature, and high mechanical strength are considered as an eager goal for portable electronics. Herein, we first propose free-standing graphene fiber electrodes containing roller-like orientated spore carbon spheres via rheological engineering. With the help of the orientated microfluidic cospinning technology and the plasma reduction method, spore carbon spheres are self-assembled and orientedly dispersed into numerous graphene flakes, forming graphene fiber electrodes enriched with internal rolling woven structures, which cannot only enhance the electrical contact between active materials but also effectively improve the mechanical strength and structure stability of graphene fiber electrodes. When the designed graphene fibers are combined with the active sulfur cathode and lithium metal anode, the assembled flexible lithium sulfur batteries possess superior electrochemical performance with high capacity (>1000 mA h g-1) and excellent cycling life as well as good mechanical properties. According to density functional theory and COMSOL simulations, the roller-like spore carbon sphere-orientated graphene fiber hosts provide reinforced trapping-catalytic-conversion behavior to soluble polysulfides and nucleation active sites to lithium metal, thus synergistically suppressing the shuttle effect of polysulfides at the cathode side and lithium dendrite growth at the anode side, thereby boosting the whole electrochemical properties of lithium sulfur batteries.

Bimetallic Coupling Strategy Modulating Electronic Construction to Accelerate Sulfur Redox Reaction Kinetics for High-Energy Flexible Li-S Batteries.

Lithium-sulfur (Li-S) batteries are considered the most promising energy storage battery due to their low cost and high theoretical energy density. However, the low utilization rate of sulfur and slow redox kinetics have seriously limited the development of Li-S batteries. Herein, the electronic state modulation of metal selenides induced by the bi-metallic coupling strategy is reported to enhance the redox reaction kinetics and sulfur utilization, thereby improving the electrochemical performance of Li-S batteries. Theoretical calculations reveal that the electronic structure can be modulated by Ni-Co coupling, thus lowering the conversion barrier of lithium polysulfides (LiPSs)and Li+, and the synergistic interaction between NiCoSe nanoparticles and nitrogen-doped porous carbon (NPC) is facilitating to enhance electron transport and ion transfer kinetics of the NiCoSe@NPC-S electrodes. As a result, the assembled Li-S batteries based on NiCoSe@NPC-S exhibit high capacities (1020mAhg-1 at 1C) and stable cycle performance (80.37% capacity retention after 500 cycles). The special structural design and bimetallic coupling strategy promote the batteries working even under lean electrolyte (7.2µLmg-1) with a high sulfur loading (6.5mgcm-2). The proposed bimetallic coupling strategy modulating electronic construction with N-doping porous carbon has jointly contributed the good redox reaction kinetics and high sulfur utilization.

Self-assembled 3D CoSe-based sulfur host enables high-efficient and durable electrocatalytic conversion of polysulfides for flexible lithium-sulfur batteries

Lithium-sulfur (Li-S) batteries are considered as promising candidates for next-generation energy storage systems. However, the commercial applications are severely limited by the sluggish kinetics and shuttling effect. Herein, we have designed an integrated free-standing functional CoSe-CNF-GO-MXene (CCGM) sulfur host with a “point-line-plane” 3D porous structure for Li-S batteries. The two-dimensional (2D) graphene, MXene and one-dimensional (1D) nanocellulose fibers combined with zero-dimensional (0D) transition metal selenide (CoSe) shows good electrical conductivity and enhanced catalytic performance, respectively. Additionally, the rationally designed porous structure (from 0D to 3D) demonstrates well-connected ion/electron transport channels, conferring the good kinetic performance. Electrochemical tests show that CoSe catalytic materials with moderate adsorption energies can catalyse both precipitation and dissolution processes of Li2S, enabling fast conversion kinetics. The density functional theory (DFT) calculations show that the synergistic effect of CoSe, Ti3C2Tx, and graphene can improve the chemisorption and catalytic performance. As a result, the 3D porous S@CCGM cathode exhibits a high initial discharge capacity of 1205.1 mAh g−1 at 0.2C and good long-term cycling performance with a low decay rate of 0.055 % per cycle at 1C. Furthermore, the gel electrolyte Li-S pouch cell successfully passes the 0–180° bending test, nailing test, and cutting test. Such design offers a new perspective for the commercialization of safe and flexible electrochemical energy-storage devices especially in Li-S batteries.

Highly conductive freestanding sulfur cathode based on low-defect graphene-PEDOT:PSS aerogel for Li-S batteries

Highly conductive freestanding cathode, featuring with a unique aerogel configuration with sulfur deposited on low-defect graphene and subsequent encapsulation in poly(3,4-ethylene-dioxythiophene):poly(styrenesulfonate), is designed and synthesized for lithium-sulfur batteries. The freestanding cathode exhibits an ultrahigh conductivity for fast ions/electrons transportation and realizes effective immobilization of polysulfides, thereby enhancing lithium storage performance. This research provides a potential for use in high-performance flexible lithium-sulfur batteries.

In Situ Growth of NiCoSe Nanoparticles/Holey Carbon Nanosheet on Carbon Cloth as an Efficient Sulfur Host for Flexible Li–S Batteries

Recently, commercial wearable electronic devices have gradually attracted research interest in flexible batteries. The electrode is the crucial component of a flexible lithium-sulfur battery, which restricts the development of flexible lithium-sulfur batteries (LSBs). Here, NiCoSe/holey carbon nanosheet in situ grown on carbon cloth (NiCoSe/CNS/CC) was successfully synthesized and used as an efficient sulfur host for the flexible sulfur cathode. Its special structure also provides optimal conditions for the loading of sulfur and promotes efficient transport of both electrons and Li-ions. Numerous polar NiCoSe nanoparticles are attached to the surface of carbon fibers, which can effectively anchor lithium polysulfides (LiPSs) by chemisorption and accelerate their conversion. Benefiting from this special architecture and the polar NiCoSe nanoparticles, the NiCoSe/CNS/CC/S demonstrates excellent electrochemical performance. At 1C, the NiCoSe/CNS/CC/S electrode delivers a discharge capacity of 454 mA h g−1 after 600 cycles. Furthermore, even at 2C, after 600 cycles, it still maintains a capacity of 426 mA h g−1, with a capacity decay of 0.079% per cycle. The NiCoSe/CNS/CC/S electrode enriches the flexible sulfur cathodes with its excellent electrochemical and mechanical properties while providing a new path for the research of flexible LSBs.

Conductive Polymer Coated Layered Double Hydroxide as a Novel Sulfur Reservoir for Flexible Lithium-Sulfur Batteries.

Lithium-sulfur battery (LSB) is widely regarded as the most promising next-generation energy storage system owing to its high theoretical capacity and low cost. However, the practical application of LSBs is mainly hampered by the low electronic conductivity of the sulfur cathode and the notorious "shuttle effect", which lead to high voltage polarization, severe over-charge behavior, and rapid capacity decay. To address these issues, a novel sulfur reservoir is synthesized by coating polypyrrole (PPy) thin film on hollow layered double hydroxide (LDH) (PPy@LDH). After compositing with sulfur, such PPy@LDH-S cathode shows a multi-functional effect to reserve lithium polysulfides (LiPSs). In addition, the unique architecture provides sufficient inner space to encapsulate the volume expansion and enhances the reaction kinetics of sulfur-based redox chemistry. Theoretical calculations have illustrated that the PPy@LDH has shown stronger chemical adsorption capability for LiPSs than those of porous carbon and LDH, preventing the shuttling of LiPSs and enhancing the nucleation affinity of liquid-solid conversion. As a result, the PPy@LDH-S electrode delivers a stable cycling performance and a superior rate capability. Flexible battery has demonstrated this PPy@LDH-S electrode can work properly with treatments of bending, folding, and even twisting, paving the way for wearable devices and flexible electronics.

Establishing highly efficient absorptive and catalytic network for depolarized high-stability lithium-sulfur batteries

Practical operation of lithium-sulfur (Li-S) batteries with high sulfur loading and efficient/stable sulfur conversion requires the suppression of the lithium polysulfides (LiPSs) shuttling and the facilitation of ion and electron transfer on the electrode material surface. Herein, a multifunctional current collector, composed of Ag@polypyrrole (PPy) coated electrospun carbon nanofibers (CNF) framework, was rationally designed to construct a highly efficient catalytic/absorptive/conductive network to improve the performance of Li-S batteries under practical operation condition. At the molecular scale, the Ag@PPy molecular not only effectively inhibits LiPSs shuttle effect, but also achieves the fast sulfur catalysis and depolarization during charge transfer due to the high conductivity of Ag nanoparticles. At the electrode scale, the three-dimensional (3D) robust fibrous nanostructure provides abundant physical space to realize high sulfur loading, maintains electrode integrity during large volume change of active sulfur and under mechanical abuse condition, as well as enables the high-flux Li+ diffusion and electrolyte flow. Consequently, Li-S batteries with the CNF/Ag@PPy current collector delivered excellent cycling stability (capacity fading of 0.048% per cycle over 500cycles at 1.0C) and high energy density (234.2 Wh kgcell-1 under high sulfur loading of 9.77 mg cm−2). Flexible Li-S batteries are also fabricated indicating the feasibility of the CNF/Ag@PPy current collector in flexible devices.

Using Organosulfur Materials to Solve Critical Challenges Facing Lithium-Sulfur Batteries

The high abundance and environmental benignity of sulfur coupled with its high energy density of nearly 2,500 Wh kg-1 render the lithium-sulfur (Li-S) battery technology a sustainable energy storage solution for the future. Unfortunately, in Li-S batteries, the sulfur cathode suffers from poor electronic and ionic conductivity and the notorious polysulfide shuttle effect. Meanwhile, the anode suffers from continuous degradation owing to the high reactivity of Li metal. Organosulfur materials may present a way to overcome these limitations. Organic functional groups bound to sulfur could enhance electronic and ionic conductivity. Limiting the polysulfide order in an organosulfur material can minimize the shuttle effect. Furthermore, organic groups could stabilize the electrolyte-anode interface.Two studies on using organosulfur materials to overcome the challenges of Li-S will be presented. The first study shows a method to rationally design organosulfide polymers that can provide inherent Li-ion conductivity. The enhancement in ionic conductivity results in an improvement in performance under high-rate and high-loading conditions. The application of such materials in flexible Li-S batteries will be showcased. In the second study, a mechanistic understanding of how organosulfide-rich interphase at the Li-metal anode improves the stripping/plating efficiency will be elucidated. By understanding the effect of different functional groups on the efficiency of the anode, a set of design rules for developing organosulfide molecules that generate a stable interface will be proposed.

Synergistic Interfacial Bonding in Reduced Graphene Oxide Fiber Cathodes Containing Polypyrrole@sulfur Nanospheres for Flexible Energy Storage

Flexible lithium sulfur batteries with high energy density and good mechanical flexibility are highly desirable. Here, we report a synergistic interface bonding enhancement strategy to construct flexible fiber-shaped composite cathodes, in which polypyrrole@sulfur (PPy@S) nanospheres are homogeneously implanted into the built-in cavity of self-assembled reduced graphene oxide fibers (rGOFs) by a facile microfluidic assembly method. In this architecture, sulfur nanospheres and lithium polysulfides are synergistically hosted by carbon and polymer interface, which work together to provide enhanced interface chemical bonding to endow the cathode with good adsorption ability, fast reaction kinetics, and excellent mechanical flexibility. Consequently, the PPy@S/rGOFs cathode shows enhanced electrochemical performance and high-rate capability. COMSOL Multiphysics simulations and density functional theory (DFT) calculations are conducted to elucidate the enhanced electrochemical performance. In addition, a flexible Li-S pouch cell is assembled and delivers a high areal capacity of 5.8 mAh cm-2 at 0.2 A g-1 . Our work offers a new strategy for preparation of advanced cathodes for flexible batteries.

Multi-functional bilayer carbon structures with micrometer-level physical encapsulation as a flexible cathode host for high-performance lithium-sulfur batteries

With the exceptional merits of high energy density, low cost, and environmental friendliness, lithium-sulfur batteries are considered to be one of the most promising next-generation flexible rechargeable batteries. However, the notorious “shuttle effect” has seriously hindered their practical applications. Herein, a strategy for designing multi-functional bilayer carbon structures is proposed, specifically, by employing a micrometer-thick graphene nanoflowers (GF) layer to encapsulate a micrometer-scale hybrid network skeleton composed of metallic Co and carbon nanotubes (CNT) as a flexible sulfur cathode host (Co/CNT@GF). Beneficial from the merits of chemical adsorption, electrocatalysis and volume expansion mitigation from the internal skeleton as well as the micrometer-level physical domain confinement by the external GF layer, the developed host could chemically trap, electrochemically catalyze, physically block and storage the lithium polysulfides. Due to the synergistic effect of these functions, the Co/CNT@GF-S delivers a superior discharge capacity of 799 mAh g−1 with a decay rate as low as 0.08 % per cycle after 400 cycles at 1 C. Even at a high sulfur loading of 8.16 mg cm−2, the average discharge capacity is as high as 5.05 mAh cm−2 in 100 cycles. This work does not only contribute to the rational design of multi-functional bilayer structures but also offers a novel design method for the commercialization of flexible lithium-sulfur batteries with high-energy–density.

Crosslinked Nanofiber‐Reinforced Solid‐State Electrolytes with Polysulfide Fixation Effect Towards High Safety Flexible Lithium–Sulfur Batteries

AbstractSolid‐state lithium–sulfur (Li–S) batteries using gel polymer electrolytes have attracted much attention owing to their higher safety compared to liquid electrolytes and lower interfacial resistance compared to ceramic electrolytes. However, except for their unsatisfactory lithium‐ion conductivity, relatively low mechanical strength, the unavoidable polysulfide shuttling in gel polymer electrolytes still limits their development. This work designed a poly(ethylene oxide)‐polyacrylonitrile (PEO‐PAN) copolymer membrane electrolyte, in which PAN fibers act as both a filler and crosslinker. This structure not only provides improved ionic conductivity, high mechanical strength, and lithium dendrite blocking ability, it also inhibits polysulfide shuttling as a result of strong polysulfide adsorption by the CNO functional groups formed during the PEO and PAN crosslinking process, which improves the safety, cycling stability and rate capability when used in Li–S batteries. A more than 96% capacity retention after 1000 bend cycles of the flexible battery is also achieved because of the high flexibility and high bonding strength of this electrolyte.

Mesoporous hierarchical NiCoSe2-NiO composite self-supported on carbon nanoarrays as synergistic electrocatalyst for flexible lithium-sulfur batteries

Lithium-sulfur batteries (LSBs) have enormous application potential in the flexible energy storage field due to their large theoretical specific capacities and high energy densities. However, lithium-sulfur batteries face a notorious shuttle effect problem. To address this challenge, this work reports a three-dimensional (3D) structure of binary transition metal selenides (B-TMSe) hierarchical composites (CC/NiCoSe2-NiO) on carbon cloth as a self-supporting sulfur host for flexible LSBs. According to the density functional theory (DFT) calculations, NiCoSe2can exert a synergetic effect of high affinity with Lithium polysulfides (LiPSs) and electrocatalytic activity to lower the adsorption energy barrier and accelerate the sluggish reaction kinetics of polysulfides. Consequently, the CC/NiCoSe2-NiO-based electrodes realize a large specific capacity of approximately 1363 mAh/g at a current density of 0.1C, excellent rate performance (454.66 mAh/g at 5C) and a reversible specific capacity of 978.9 mAh/g at 1C, along with impressive cycling stability with an attenuation rate of 0.038% per cycle for 1000 cycles. They also achieve a large reversible cycle capacity of 919.43 mAh/g at 0.2C even at a high sulfur loading (3.5 mg/cm2). With a lean electrolyte (E/S ratio 10 µL/mg) and a high sulfur loading of 2.65 mg/cm2, a large capacity of 934.1 mAh/g is retained after 150 cycles at 0.5C. The assembled pouch cells from S@CC/NiCoSe2-NiO electrodes show a high initial discharge capacity of 1039.5 mAh/g at 1C at a sulfur loading of 2.65 mg/cm2 and maintain strong stability under high twisting and buckling.

Self-extinguishing Janus separator with high safety for flexible lithium-sulfur batteries

Flexible lithium-sulfur (Li-S) batteries are considered one of the most promising candidates for high-energy-density storage devices in wearable electronics. However, the safety problem severely restricts the practical application of Li-S batteries because of the possible occurrence of thermal runaway caused by battery short circuits and combustible components, particularly under bending conditions. The development of advanced separators that can suppress lithium dendrite growth and are incombustible is the key to improving the safety of flexible Li-S batteries. In this work, a nonflammable multifunctional Janus separator with self-extinguishing capability, high thermal stability, high thermal conductivity, good electrolyte infiltration, uniform lithium deposition, and efficient polysulfide shuttling inhibition, is proposed. The separator is composed of polyacrylonitrile (PAN) fiber and decabromodiphenyl ethane (DBDPE) membrane as well as functional layers of boron nitride (BN) for suppressing lithium dendrite growth and reduced graphene oxide (rGO) for accelerating the sulfur convention kinetics. As a result, the Li-S battery with a sulfur mass loading of 2.7 mg cm−2 delivers a specific capacity of 916.8 mA h g−1 after 100 cycles at 0.1 C and maintains a stable performance during intermittent thermal shock. Moreover, the Li-S pouch cell with a sulfur mass loading of 8 mg exhibits a high capacity of 6.3 mA h under bending conditions.

MoO3/MoS2 flexible paper as sulfur cathode with synergistic suppress shuttle effect for lithium-sulfur batteries

Lithium-sulfur (Li-S) batteries have become one of the most promising candidate systems for electronic energy storage applications. However, the shuttle effect, which is caused by the intermediate lithium polysulfide (LiPs) dissolving in the electrolyte and commuting between electrodes, is the main factor leading to the deterioration of the electrochemical performance of the Li-S batteries. Different from most single physical confinement or chemical adsorption, we report a hydrogen ion intercalated molybdenum trioxide (MoO3-HI) with embedded molybdenum disulfide (MoS2) flexible paper as S hosts not only restricted soluble LiPs passively with physical adsorption, but also accelerate actively the transformation rate of polysulfides with strong chemical affinity and catalytic activity. Furthermore, the theoretical calculation showed that the MoO3-HI/MoS2 equipped the ability of directly convert S8 molecules into LiS2 molecules, eliminating the formation of lithium polysulfide. Based on the new strategy of synergistic suppress shuttle effect, the Li-S battery with MoO3-HI/MoS2/S cathode achieved a capacity of 911.3 mAh g − 1 after 500 cycles with outstanding cycle stability. In addition, MoO3-HI/MoS2 paper as a flexible carrier for Li-S batteries can be folded repeatedly and keep the structure intact. Hence, the current work provides a novel paper electrode with active and passive dual synergistic inhibition of shuttle effect characteristics for high performance flexible lithium-sulfur batteries.

Free-Standing Titanium Nitride Films as Carbon-Free Sulfur Hosts for Flexible Lithium–Sulfur Batteries

Free-Standing Titanium Nitride Films as Carbon-Free Sulfur Hosts for Flexible Lithium–Sulfur Batteries

Freestanding and Sandwich MXene-Based Cathode with Suppressed Lithium Polysulfides Shuttle for Flexible Lithium-Sulfur Batteries.

Flexible lithium-sulfur (Li-S) batteries with high mechanical compliance and energy density are highly desired. This manuscript reported that large-area freestanding MXene (Ti3C2Tx) film has been obtained through a scalable drop-casting method, significantly improving adhesion to the sulfur layer under the continuously bent. Titanium oxide anchored on holey Ti3C2Tx (TiO2/H-Ti3C2Tx) was also produced by the well-controlled oxidation of few-layer Ti3C2Tx, which greatly facilitates lithium ion transport as well as prevents the shuttling of lithium polysulfides. Therefore, the obtained sandwich electrode has demonstrated a high capacity of 740 mAh g-1 at 2 C and a high capacity retention of 81% at 1 C after 500 cycles. Flexible Li-S batteries based on this sandwich electrode have a capacity retention as high as 95% after bending 500 times. This work provides effective design strategies of MXene for flexible batteries and wearable electronics.

Polaron hopping-mediated dynamic interactive sites boost sulfur chemistry for flexible lithium-sulfur batteries

Developing flexible and robust sulfur cathodes while boosting sulfur chemistry is a crucial enabler for the implementation of energy-dense flexible lithium-sulfur (Li-S) batteries. Here, we report an all-electrochem-active hybrid sulfur cathode by integrating nest-like O-defective RuO2 (RuO2-x) with sulfur to simultaneously realize decent flexibility, durability, and energy density. The mechanically robust RuO2-x with high electrical conductivity, active capacity contribution and high electrocatalytic activity is proved to be an ideal matrix to unlock high gravimetric and volumetric performances. Moreover, from jointly chemical and physical perspectives, it is confirmed that the polaron hopping-mediated dynamic interactive sites are formed in this RuO2-x/S system, which overcomes the reaction barrier and expedites Li-S chemistry. Impressively, the prototype pouch cells exhibit superb capacity retention under harsh bending conditions and harvest jointly high energy densities of 328 Wh kg−1 and 357 Wh L−1 under lean electrolyte condition, holding great promise for achieving energy-dense flexible Li-S batteries.

Lithium-Sulfur Batteries Meet Electrospinning: Recent Advances and the Key Parameters for High Gravimetric and Volume Energy Density.

Lithium–sulfur (Li–S) batteries have been regarded as a promising next‐generation energy storage technology for their ultrahigh theoretical energy density compared with those of the traditional lithium‐ion batteries. However, the practical applications of Li–S batteries are still blocked by notorious problems such as the shuttle effect and the uncontrollable growth of lithium dendrites. Recently, the rapid development of electrospinning technology provides reliable methods in preparing flexible nanofibers materials and is widely applied to Li–S batteries serving as hosts, interlayers, and separators, which are considered as a promising strategy to achieve high energy density flexible Li–S batteries. In this review, a fundamental introduction of electrospinning technology and multifarious electrospinning‐based nanofibers used in flexible Li–S batteries are presented. More importantly, crucial parameters of specific capacity, electrolyte/sulfur (E/S) ratio, sulfur loading, and cathode tap density are emphasized based on the proposed mathematic model, in which the electrospinning‐based nanofibers are used as important components in Li–S batteries to achieve high gravimetric (W G) and volume (W V) energy density of 500 Wh kg−1 and 700 Wh L−1, respectively. These systematic summaries not only provide the principles in nanofiber‐based electrode design but also propose enlightening directions for the commercialized Li–S batteries with high W G and W V.

Free-Standing MrGO/S Film with Suppressive Shuttle Effect for High-Performance Flexible Lithium-Sulfur Batteries

Lithium-sulfur (Li–S) batteries have high expectations for large-scale applications in energy devices because of their high theoretical capacity and low cost. However, due to the insulation and shu...

Thirty-minute synthesis of hierarchically ordered sulfur particles enables high-energy, flexible lithium-sulfur batteries

An innovative lithium-sulfur (Li-S) battery technology is proposed that provides high energy density, fast charging, and mechanical flexibility. Via the rapid (30 min) one-pot reaction of elemental sulfur and vinyl phosphonic acid (VPA), SVPA microparticles containing dissimilar sulfur allotropes were developed. The spontaneous formation of wrinkles and pores on the particles facilitates electrolyte access and alleviates mechanical stress during battery cycling. The large surface area created by the ordered sulfur domains enhances lithium diffusion coefficients and facilitates polysulfide conversion kinetics in the Li-S cells, leading to a high discharge capacity of 1529 mAh·g −1 at 0.05 C and excellent rate performance (721 mAh·g −1 at 7 C). Additionally, owing to the inherent electrode porosity imparted by SVPA microparticles, a high areal capacity of ~5 mAh·cm −2 is obtained at increased cathode loadings. Abundant phosphonate moieties at the surfaces and interfaces of particles act as effective chemical anchors for lithium polysulfides, thereby mitigating the shuttle effects, which can prolong cycle lives at various C rates. The impressive properties of the SVPA microparticles are demonstrated for Li-S pouch cells, which exhibit stable operation under various deformations and highlight the SVPA microparticles as a promising candidate for next-generation Li-S batteries for wearable electronics A simple but radical approach is proposed to advance sulfur electrodes with smart nanostructures via the rapid one-pot reaction between elemental sulfur and vinyl phosphonic acid. This study serves as a platform for the development of next-generation Li-S batteries with high energy density, rate capability, and mechanical flexibility. • Hierarchically ordered sulfur electrodes were developed via rapid, solvent-free synthesis of SVPA microparticles. • The ordered sulfur domains and abundant phosphonate moieties at wrinkled surfaces of SVPA improved redox kinetics and cathode integrity. • Li-S batteries based on SVPA microparticles empowered one of the highest areal capacity, excellent rate capability and flexible characteristics