Binder-free Anode For Sodium Ion Batteries Research Articles

Stable Structure and Fast Ion Diffusion: A Flexible MoO2@Carbon Hollow Nanofiber Film as a Binder-Free Anode for Sodium-Ion Batteries with Superior Kinetics and Excellent Rate Capability.

Designing innovative anode materials that exhibit excellent ion diffusion kinetics, enhanced structural stability, and superior electrical conductivity is imperative for advancing the rapid charge-discharge performance and widespread application of sodium-ion batteries. Hollow-structured materials have received significant attention in electrode design due to their rapid ion diffusion kinetics. Building upon this, we present a high-performance, free-standing MoO2@hollow carbon nanofiber (MoO2@HCNF) electrode, fabricated through facile coaxial electrospinning and subsequent heat treatment. In comparison to MoO2@carbon nanofibers (MoO2@CNFs), the MoO2@HCNF electrode demonstrates superior rate capability, attributed to its larger specific surface area, its higher pseudocapacitance contribution, and the enhanced diffusion kinetics of sodium ions. The discharge capacities of the MoO2@HCNF (MoO2@CNF) electrode at current densities of 0.1, 0.2, 0.5, 1.0, 2.0 and 5.0 A g-1 are 195.55 (155.49), 180.98 (135.20), 163.81 (109.71), 144.05 (90.46), 121.16 (71.21) and 88.90 (44.68) mAh g-1, respectively. Additionally, the diffusion coefficients of sodium ions in the MoO2@HCNFs are 8.74 × 10-12 to 1.37 × 10-12 cm2 s-1, which surpass those of the MoO2@CNFs (6.49 × 10-12 to 9.30 × 10-13 cm2 s-1) during the discharging process. In addition, these prepared electrode materials exhibit outstanding flexibility, which is crucial to the power storage industry and smart wearable devices.

General synthesis of metal selenides embedded in N-doped carbon nanofibers covered with in-situ grown carbon nanotubes as binder-free anodes for sodium-ion storage

Due to the high theoretical capacity, metal selenides are considered to be promising materials for energy storage. Unfortunately, their practical use is still hampered by their flat electronic conductivity, large volume change and poor ion transport kinetics. In this work, a general synthesis method is presented for the preparation of metal selenides embedded in N-doped carbon nanofibers with in-situ grown carbon nanotubes (CNTs) on the surface (MSe2@NCF/CNTs, M=Co, Ni, Fe) as binder-free anodes for sodium-ion batteries. Metal precursors can be used as catalysts and as active materials after selenization treatment. The metal selenides are dispersed in the carbon nanofibers and CNTs, which effectively prevents agglomeration of the particles. The in-situ grown CNTs are strongly coupled to the surface of nanofibers, which improves the electrical conductivity, allows for efficient electrolyte infiltration and buffers the volume expansion during the charge/discharge processes. As a result, CoSe2@NCF/CNTs achieves extremely high reversible capacity, stable cycling stability (441.2 mAh g−1 after 1000 cycles at 200 mA g−1), and excellent rate properties (375.4 mAh g−1 at 2 A g−1) when used as binder-free anodes for sodium-ion batteries. The fast charge transport and Na+ diffusion rates, as well as a pseudocapacitance Na+ storage mechanism, are revealed by kinetic analysis. This synthetic approach is extendable to assembling CNTs in-situ on other substrates for advanced energy storage systems.

Hierarchical CoSe2/TiN/nitrogen-doped carbon nanofibers wrapped with carbon nanotubes: A binder-free anode for enhanced sodium-ion storage

Transition metal chalcogenide anodes have attracted significant attention for sodium-ion batteries (SIBs) owing to their relatively high theoretical capacity. However, the inherently poor electronic conductivity and rate performance hinder their practical application. In this study, hierarchically structured CoSe2/TiN/nitrogen-doped carbon nanofibers wrapped with in-situ grown carbon nanotubes (CNTs) on the surface (denoted as CoSe2@N-TCF/CNTs) are designed and fabricated as binder-free anodes for SIBs. The rational design can effectively avoid the agglomeration of CoSe2 nanoparticles, improve the conductivity of the composite materials, provide enough space for electrolyte penetration and volume expansion during the cycling process and shorten the transmission paths of electrons and Na+. With these structural and compositional advantages, the as-obtained hierarchical CoSe2@N-TCF/CNTs deliver a high reversible capacity of 401.2 mAh g−1 after 1000 cycles at 0.2 A g−1 and maintained at 353.7 mAh g−1 even at a high current density of 2 A g−1 when directly used as a binder-free anode for SIBs. The superior sodium-ion storage performance can be attributed to the decreased charge transfer resistance, improved Na+ diffusion rate and the pseudocapacitance behavior, as is evidenced by kinetics analysis.

In-situ pyrolysis preparation of Fe3O4@CNTs/CC as binder-free anode for sodium-ion batteries

N-doped carbon nanotubes (CNTs) coated Fe3O4 nanoparticles were prepared on flexible carbon cloth (CC) by in situ thermal decomposition method. The obtained Fe3O4@CNTs/CC composites have a three-dimensional network structure. The carbon nanotubes on the flexible carbon cloth can increase the conductivity of the electrode and alleviate the volume change of the active material Fe3O4 during sodium storage. The discharge capacity is 363.6 mAh g−1 after 200 cycles at a current density of 0.2 A g−1. The Fe3O4@CNTs/CC delivers stable discharge capacity of 542, 403, 312, 191, and 152 mAh g−1 at 0.1, 0.5, 1, 2 and 3 A g−1, respectively, having good rate performance.

Encapsulation of KTi2(PO4)3 nanoparticles in porous N-doped carbon nanofibers as a free-standing electrode for superior Na/K-storage performance

Herein, a self-supporting electrospinning film of porous N-doped carbon nanofibers impregnated with KTi2(PO4)3 nanoparticles (abbreviated as NF-KTP) is constructed. The free-standing NF-KTP exhibits excellent flexibility and is directly adopted as a binder-free anode for sodium-ion batteries (SIBs) and potassium-ion batteries (PIBs). The introduction of conductive N-doped carbon matrix enables enhanced intrinsic electronic conductivity and fast ion diffusion kinetics, as well as the fabrication of porous nitrogen-doped interconnected carbon fibers impregnated with KTi2(PO4)3 nanoparticles can offer a short transport path of sodium/potassium ions and buffer the volume expansion during repetitive intercalation/deintercalation. Therefore, the NF-KTP electrode delivers an initial charge capacity of 116.8 mAh g−1 at 0.2 C, superb rate capability of 107.8 mAh g−1 at 50 C and impressive cycling stability with a capacity retention of 92.8 % for 1000 cycles at 5 C in SIBs. Even at 0 °C and 50 °C, it still retains marvelous rate performance with capacities of 99.8 and 106.3 mAh g−1 at 50 C, respectively. Meanwhile, as an anode material for PIBs, NF-KTP also displays good electrochemical performances, as reflected by its exceptional rate performance (99.3 mA h g−1 at 10 C) and superb cycling performance (with no capacity fading after 300 cycles at 5 C). These satisfactory electrochemical properties can be ascribed to the superiority of the stable 3D network formed by KTP nanofibers. Such a simple and effective strategy may provide a new vision for other materials applied in energy storage systems.

In situ growth Zn2GeO4 nanorods network on 3D conductive foam as free standing electrode for sodium-ion batteries

• Zn 2 GeO 4 nanorods were anchored on nickel foam as a binder free anode for SIBs. • Zn 2 GeO 4 @NF anode shows 3D interlinked porous network structure. • The Zn 2 GeO 4 @NF showed excellent electrochemical sodium storage performances. Large-scale energy storage and scarcity of lithium bring exploration interest of high-performance anode materials for sodium-ion batteries (SIBs). Herein, Zn 2 GeO 4 nanorods was anchored directly on nickel foam to form a free standing, binder free anode for SIBs, though a facile hydrothermal method. Benefiting from composite effect of nanorod network structure, conductive network and mechanical stability, the Zn 2 GeO 4 @NF reaches an initial discharge capacity of 882.0 mAh g -1 and maintains a capacity of 435.6 mAh g -1 after 400 cycles at 0.1A g -1 . At a higher current density (2 A g -1 ) Zn 2 GeO 4 @NF also delivers a reversible discharge capacity of 239.7 mAh g -1 , which is higher than that for the Zn 2 GeO 4 particles.

Effective Combination of Fe2O3 with 3D Graphene Foam for Preparation of Binder-Free Anode for Sodium-Ion Batteries

Effective Combination of Fe2O3 with 3D Graphene Foam for Preparation of Binder-Free Anode for Sodium-Ion Batteries

Binary self-assembly of ordered Bi4Se3/Bi2O2Se lamellar architecture embedded into CNTs@Graphene as a binder-free electrode for superb Na-Ion storage

With the development of various flexible electronic devices, flexible energy storage devices have attracted more research attention. Binder-free flexible batteries, without a current collector, binder, and conductive agent, have higher energy density and lower manufacturing costs than traditional sodium-ion batteries (SIBs). However, preparing binder-free anodes with high electrochemical performance and flexibility remains a great challenge. In this study, a binary self-assembly composite of an ordered Bi4Se3/Bi2O2Se lamellar architecture wrapped by carbon nanotubes (CNTs) was embedded in graphene with strong interfacial interaction to form Bi2O2Se/Bi4Se3@CNTs@rGO (BCG), which was used as a binder-free anode for SIBs. A unique “one-changes-into-two” phenomenon was observed: the layered Bi2Se3 was transformed into a unique layered Bi4Se3/Bi2O2Se heterojunction structure, which not only provides more electrochemical channels but also reduces internal stress to improve the stability of the material structure. BCG-2 showed excellent sodium-ion storage, delivering a reversible capacity of 346 mA h/g at 100 mA/g and maintaining a capacity of 235 mA h/g over 50 cycles. Even at a high current density of 1 A/g, it retains a capacity of 105 mA h/g after 1000 cycles. This unique design concept can also be employed in synthesizing other binder-free electrodes to improve their properties.

Dual carbon composited with Co9S8 through C-S bond as a high performance Binder-Free anode for Sodium-Ion batteries

Cobalt sulfide/ carbon cloth composites with conversion reactions mechanism as anodes for sodium-ion storage have attracted tremendous attention due to high theoretical capacity and binder-free. However, the severe volume change and exfoliation of cobalt sulfide makes composite materials cycle stability and rate capability unsatisfactory. In this work, we report dual carbon materials composited with Co9S8 through C-S bonds to further stabilize the structure of the composite (Co9S8/CC@C). Dual C-S bonds can provide ultrafast charge transport paths between Co9S8 and carbon materials, further ensure the stable reversible conversion reaction process. Furthermore, dual C-S bonds effectively prevent exfoliation of Co9S8 from carbon cloth, significantly improved structural stability of the composite. Benefiting from dual C-S bonds, the Co9S8/CC@C composite electrode delivers high reversible capacity of 785.6 mAh g−1 at 0.1 A g−1 after 100 cycles with capacity retention of 74.81 %. Notably, it preserves a considerable capacity of 417.2 mAh g−1 after 1000 cycles at 5 A g−1. This work provides a good reference for improving cycle stability and rate performance of Co9S8-based electrodes to designing advanced anodes for sodium-ion batteries.

Carbon-coated tungsten diselenide nanosheets uniformly assembled on porous carbon cloth as flexible binder-free anodes for sodium-ion batteries with improved electrochemical performance

As large-scale energy storage systems, rechargeable sodium-ion batteries (SIBs) are promising to replace the lithium-ion batteries. Among transition-metal dichalcogenides, which exhibit high theoretical capacities and specific two-dimensional layered structures, tungsten diselenide (WSe2) is an efficient anode material for SIBs owing to the good energetics and large lattice parameter. In this study, well-crystallized WSe2 nanosheets uniformly assembled on a porous carbon cloth (WSe2@PCC) were fabricated by an underwater electrical explosion of a tungsten wire, dip coating, and complete selenization from WO3 to WSe2. To further improve the cycling performance of the WSe2@PCC electrode, a carbon coating was carried out by simply adding sucrose into a WO3 ink before dip coating. The carbon-coated WSe2@PCC (C@WSe2@PCC) electrode exhibited outstanding electrochemical performances as a flexible and binder-free anode for SIBs due to enhanced electrical conductivity and mitigation of volume expansion of WSe2 during repeated sodiation/desodiation. Benefiting from unique structural merits and efficient carbon coating, C@WSe2@PCC can deliver large reversible areal capacity of 1.37 and 1.05 mA h cm−2 at the 1st and 150th cycles, respectively, with excellent capacity retention and Coulombic efficiency even at a high current density of 0.75 mA cm−2.

Na‐Ion Batteries: A Confined Replacement Synthesis of Bismuth Nanodots in MOF Derived Carbon Arrays as Binder‐Free Anodes for Sodium‐Ion Batteries (Adv. Sci. 16/2019)

In article 1900162, Yaping Wang, Anqiang Pan, Shuquan Liang, and co-workers embed bismuth nanodots in metal–organic framework–derived carbon arrays on carbon fibers through a confined replacement reaction. As binder-free anode for sodium-ion batteries, nanosized bismuth and plenty phase boundaries enable fast sodium storage kinetics.

A Confined Replacement Synthesis of Bismuth Nanodots in MOF Derived Carbon Arrays as Binder-Free Anodes for Sodium-Ion Batteries.

The inferior tolerance with reversible accommodation of large‐sized Na+ ion in electrode materials has plagued the adaptability of sodium‐ion chemistry. The sluggish diffusion kinetics of Na+ also baffles the desirability. Herein, a carbon fiber supported binder‐free electrode consisting of bismuth and carbon composite is designed. Well‐confined bismuth nanodots are synthesized by replacing cobalt in the metal–organic frameworks (MOF)–derived, nitrogen‐doped carbon arrays, which are demonstrated with remarkable reversibility during sodiation and desodiation. Cobalt species in the pristine MOF catalyze the graphitization around organic components in calcination, generating a highly conductive network in which the bismuth is to be embedded. The uniformly dispersed bismuth nanodots provide plenty boundaries and abundant active sites in the carbon arrays, where fast sodium storage kinetics are realized to contribute extra capacity and excellent rate performance.

In Situ Fabrication of Branched TiO2 /C Nanofibers as Binder-Free and Free-Standing Anodes for High-Performance Sodium-Ion Batteries.

Herein, 1D free-standing and binder-free hierarchically branched TiO2 /C nanofibers (denoted as BT/C NFs) based on an in situ fabrication method as an anode for sodium-ion batteries are reported. The in situ fabrication endows this material with large surface area and strong structural stability, providing this material with abundant active sites and smooth channels for fast ion transportation. As a result, BT/C NFs with the character of free-standing membranes are directly used as binder-free anode for sodium-ion batteries, delivering a capacity of 284 mA h g-1 at a current density of 200 mA g-1 after 1000 cycles. Even at a high current density of 2000 mA g-1 , the reversible capacity can still achieve as high as 204 mA h g-1 . By means of kinetic analysis, it is demonstrated that the remarkable surface pseudocapacitive behavior is also a major factor to achieve excellent performance. The rationally designed structure coupled with the inherent pseudocapacitive behavior gives this material potential for sodium-ion batteries.

Functionalized N-Doped Carbon Nanotube Arrays: Novel Binder-Free Anodes for Sodium-Ion Batteries.

Boosting electrochemical sodium storage properties is achieved by utilizing functionalized N-doped carbon nanotube arrays (NCNAs) as anode materials. The NCNA anodes are first fabricated by self-polymerization of dopamine on cobalt hydroxide nanorod arrays as the template. The NCNAs with diameters of 100-120 nm are grown vertically to Ni foam, forming self-supported nanotube arrays. Such a structure has attractive advantages including large porosity and surface area, good electrical conductivity and mechanical strength. Consequently, the NCNAs are demonstrated to achieve excellent sodium storage performances with high capacity (335 mA h g-1 at 100 mA g-1), good rate capability (140 mA h g-1 at 2 A g-1), and superior capacity retention of 90.9% after 500 cycles. Especially, high performance is verified in the assembled full cells by using an NCNA anode and Na3V2(PO4)3/C cathode. The developed synthetic strategy provides an effective approach for the fabrication of advanced heteroatom-doped carbon-based electrodes for electrochemical energy storage.

Ultrathin carbon-coated Sb2Se3 nanorods embedded in 3D hierarchical carbon matrix as binder-free anode for high-performance sodium-ion batteries

A high-performance freestanding anode composed of carbon-coated Sb2Se3 nanorods and conductive carbon matrix of reduced graphene oxide (rGO) and multi-walled carbon nanotubes (MWCNTs) for sodium-ion batteries (SIBs) is fabricated by a modified vacuum filtration, subsequent free-drying, and annealing. In this electrode architecture, the ultrathin amorphous carbon layers connect Sb2Se3 nanorods with the 3D interconnected carbon matrix. This unique cross-bonding network structure with good electrical conductivity and volume buffering effect improves the structural stability during repeating Na+ insertion/extraction and electrochemical performance. As a binder-free anode for SIBs, it reveals preferable initial charge-specific capacity of 792 mA h g−1 at a current density of 100 mA g−1, and simultaneously sustains 100 cycles at 500 mA g−1 with a specific capacity of 485 mA h g−1, and capacity retention ratio of 90%. The flexible Sb2Se3-based material as an anode can expectantly apply to the further development of advanced low-cost and flexible electronics for SIBs.

In situ assembly of 2D cobalt sulfide on stainless steel mesh as a binder-free anode for sodium ion batteries

Sodium-ion batteries (SIBs) are promising alternatives to lithium-ion batteries (LIBs) in view of the natural abundance and low cost of sodium resource. Constructing high-performance anode is essential and challenging for the futuristic SIBs development. Transition metal sulfides have been proved as promising anode materials for SIBs due to their large specific capacities. Here, in situ assembly of cobalt sulfide nanosheets on stainless steel mesh (SSM/CoS) as a binder-free anode for SIBs is carried out through a facile electrochemical deposition procedure. The SSM/CoS products are directly used as anode electrodes without addition of binder and conductive additives. As a result, a high capacity of 313 mAh g−1 is obtained at a current density of 50 mA g−1 over 100 cycles.

Hierarchical Carbon@SnS2 Aerogel with "Skeleton/Skin" Architectures as a High-Capacity, High-Rate Capability and Long Cycle Life Anode for Sodium Ion Storage.

Developing high-performance electrode materials with high energy and long-term cycling stability is a hot topic and of great importance for sodium ion batteries (SIBs). In this work, a highly porous carbon/tin sulfide aerogel with a "skeleton/skin" morphology (SSC@SnS2) has been developed and further used as a binder-free anode for SIBs. This SSC@SnS2 electrode delivers a high specific capacity of 612 mA h g-1 at 0.1 A g-1, a good rate capability, and a long-term cycling stability up to 1000 times with an average Coulombic efficiency of ∼99.9%. Meanwhile, this SSC@SnS2 aerogel also achieves a stable cycling performance even at a high current density up to 5.0 A g-1. The fast-yet-stable sodium ion storage performance of the prepared SSC@SnS2 aerogel can be ascribed to the reasons that (i) the carbon nanofiber/graphene skeleton provides unimpeded pathways for the rapid transfer of electrons; (ii) thin SnS2 skin with nonaggregated morphology can provide a great number of active sites for sodium ion storage; (iii) the porous structure of the SSC@SnS2 aerogel ensures a rapid penetration of electrolyte and can further accommodate the volume expansion of active SnS2 nanoflakes; and (iv) the intermediate product of Na15Sn4 alloy contributes greatly to the sodium ion storage performance of the SSC@SnS2 aerogel. The excellent electrochemical performances coupling with the unique structural features of this SSC@SnS2 aerogel make it a promising anode candidate for SIBs.

Enhanced sodium storage capability enabled by super wide-interlayer-spacing MoS2 integrated on carbon fibers

Developing advanced electrode materials for effective pseudocapacitive charge storage is one of effective strategies to enhance the rate capability and cycling stability of sodium ion storage devices. Herein, we fabricate MoS2 nanoflowers with super wide interlayer spacing (nearly twice as large as that of the original MoS2) supported on carbon fibers (named as E-MoS2/carbon fibers) and demonstrate its superior electrochemical performances as flexible and binder-free anodes for sodium-ion batteries (SIBs) and sodium-ion hybrid capacitors (SIHCs). Grafting MoS2 nanoflowers onto the carbon fiber networks not only ensures the fast electron transfer, but also endows it with flexible feature. The super wide interlayer spacing of MoS2 nanoflowers can not only decrease the ion diffusion pathways and resistance, but also increase their available and accessible active surface area, thus guaranteeing the rapid mass transport. Also, it can accommodate the large internal strain during discharge/charge processes. Benefiting from these combined structure merits, the E-MoS2/carbon fibers electrodes deliver an ultralong cycling stability up to 3000 cycles and the superior rate capacity of 104mAhg−1 at 20Ag−1, which just takes ca. 18.7s to fully charge/discharge. When further employed as the anode for SIHCs, it delivers high energy and power densities due to the high pseudocapacitive charge storage of the super wide interlayer spacing E-MoS2/carbon fibers.

Controllable N-Doped CuCo2 O4 @C Film as a Self-Supported Anode for Ultrastable Sodium-Ion Batteries.

Rational synthesis of flexible electrodes is crucial to rapid growth of functional materials for energy-storage systems. Herein, a controllable fabrication is reported for the self-supported structure of CuCo2 O4 nanodots (≈3 nm) delicately inserted into N-doped carbon nanofibers (named as 3-CCO@C); this composite is first used as binder-free anode for sodium-ion batteries (SIBs). Benefiting from the synergetic effect of ultrasmall CuCo2 O4 nanoparticles and a tailored N-doped carbon matrix, the 3-CCO@C composite exhibits high cycling stability (capacity of 314 mA h g-1 at 1000 mA g-1 after 1000 cycles) and high rate capability (296 mA h g-1 , even at 5000 mA g-1 ). Significantly, the Na storage mechanism is systematically explored, demonstrating that the irreversible reaction of CuCo2 O4 , which decomposes to Cu and Co, happens in the first discharge process, and then a reversible reaction between metallic Cu/Co and CuO/Co3 O4 occurrs during the following cycles. This result is conducive to a mechanistic study of highly promising bimetallic-oxide anodes for rechargeable SIBs.

Bismuth nanosheets grown on carbon fiber cloth as advanced binder-free anode for sodium-ion batteries

The bismuth nanosheets grown on carbon fiber cloth were designed. For sodium-ion batteries, the Bi/CFC electrode exhibited a high reversible capacity of 350 and 240mAhg−1 after 300cycles at 50 and 200mAg−1, as well as a good rate capability. Besides, the electrode displayed two flat potential profiles during the charge/discharge process. The results suggest that the Bi/CFC electrode has excellent potential as an anode for sodium-ion batteries.