Superior Long-term Cycling Stability Research Articles

Towards reusable 3D-printed graphite framework for zinc anode in aqueous zinc battery

Aqueous zinc ion batteries (AZIBs) are an increasingly popular high-safety and eco-friendly energy storage solution. However, the development of high-performance zinc (Zn) anodes remains a formidable challenge, primarily due to dendrite formation and poor reversibility. To address these challenges, this study harnesses the potential of digital light process (DLP) 3D printing technology to fabricate reduced graphite oxide-based 3D gyroid structure (3DP-rGG) as zinc anode frameworks for aqueous zinc batteries. The 3D-printed structure effectively regulates local current density distribution, offering ample nucleation sites and free space for inducing uniform zinc deposition and accommodating diminutive zinc nodules. Consequently, the 3D-printed graphite framework demonstrates remarkable reversibility in zinc plating and stripping processes, resulting in commendable coulombic efficiency and low voltage hysteresis. The full battery with a 3D-printed zinc anode, incorporating a polyaniline-intercalated vanadium oxide cathode (PVO), exhibits high specific capacity and superior long-term cycling stability. Remarkably, the robust 3DP-rGG structure can be reused over ten times without any discernible impact on its electrochemical performance, thereby underscoring the potential of this controllable and efficient fabrication of 3D graphite current collectors as a promising solution to develop reusable 3D frameworks for high-performance metal batteries.

Carbonized polyacrylonitrile-coated three-dimensional porous TiP2O7 as a high-rate capability anode for lithium-ion batteries

TiP2O7 is a hopeful anode material for lithium-ion batteries (LIBs) due to its three-dimensional (3D) open skeletons, excellent ion transfer kinetics, and good structural stability. However, the inferior intrinsic electronic conductivity degrades seriously the electrochemical performance of LIBs. Herein, a strategy of carbonized polyacrylonitrile-coated TiP2O7 (TPO/cPAN) with 3D porous structures was proposed to enhance Li+-storage capability. The TPO/cPAN modified with 30 wt% polyacrylonitrile and calcined at 800 ℃ delivers superior long-term cycling stability at 0.5 A g−1 and excellent rate capacities of 558.7, 523.8, 477.5, 409.8, and 303.4 mAh g−1 at 0.1, 0.2, 0.4, 0.8, and 1.6 A g−1, respectively. Structural characterizations and electrochemical analysis reveal that the pyrolytic N-doped carbon layer markedly ameliorates the electron transferability and protects the electrode from organic electrolyte erosion. Meanwhile, the design of 3D porous structures and the generation of rich oxygen defects facilitate Li+ transport and pseudocapacitance energy storage. The work provides a novel pathway for optimizing the electron/ion migration of polyanionic electrode materials.

Boosting the high-rate performance of lithium-ion battery anodes using MnCo2O4/Co3O4 nanocomposite interfaces.

Herein, a mesoporous MnCo2O4/Co3O4 nanocomposite was fabricated using a polyvinylpyrrolidone (PVP)-assisted hydrothermal synthesis method by maintaining only the non-stoichiometric ratio of Mn and Co (2 : 6), leading to an extra phase of Co3O4 coupled with MnCo2O4. Microstructural analysis showed that the obtained sample has a uniform nanowire-like morphology composed of interconnected nanoparticles. The stoichiometric ratio (2 : 4) was maintained to synthesize pure MnCo2O4 for comparative analysis. However, the obtained structure of pure MnCo2O4 was found to be irregular and fragile. After their employment as anode-active materials, the nanocomposite electrode showed superior high rate capability (1043.8 mA h g-1 at 5C) and long-term cycling stability (773.6 mA h g-1 after 500 cycles at 0.5C) in comparison to the pure MnCo2O4 electrode (771.5 mA h g-1 at 5C and 638.9 mA h g-1 at 0.5C after 500 cycles). It was believed that the extra phase of Co3O4 may also participate in the electrochemical reactions due to its high electrochemically active nature. Benefiting from the appealing architectural features and striking synergistic effect, the integrated MnCo2O4/Co3O4 nanocomposite anode exhibits excellent electrochemical properties and high cycle stability for LIBs.

MoS2@CoS2 heterostructured tube-in-tube hollow nanofibers with enhanced reaction reversibility and kinetics for sodium-ion storage

Rational synergism in spatial nanostructures and heterogeneity are effective ways to enhance reaction reversibility and kinetics of materials for sodium-ion battery electrodes. Herein, we have designed MoS2@CoS2 heterostructured tube-in-tube hollow nanofibers via simple electrospinning, pyrolysis and sulfuration processes. The unique double-walled tubular structure resulted from a stepwise crystallization accompanied by pyrolysis volume shrinkage. It has appropriate void space and abundant MoS2@CoS2 heterointerfaces that can effectively avoid the volumetric change during the reaction process and accelerate the whole infiltration of the electrolyte. The formed MoS2/CoS2 heterojunction introduces a built-in electric field, which increases the adsorption energy and reduces the migration energy barrier of sodium ions. The synergies between distinctive hollow structures and heterogeneous compositional advantages lead to enhanced electrochemical performance for sodium storage with remarkable reversible capacity (858.3 mAh g–1 at 0.5 A g–1), high-rate performance (555.7 mAh g–1 at 5 A g–1), and superior long-term cycling stability (399.6 mAh g–1 after 1400 cycles at 8 A g–1). This rational spatial structures and heterogeneity synergetic strategy provide favorable inspiration for designing extraordinary performance electrode materials for sodium-ion batteries.

Construction of FeSbO4-Sb2O4 hetero-nanocrystals anchored on reduced graphene oxide sheets for superior lithium and sodium storage

Antimony-based oxides with conversion-alloying/dealloying mechanism have attracted great attentions as alternative anode materials for lithium/sodium-ion batteries due to their high theoretical capacities. However, slow reaction kinetics, inherent poor conductivity and large volume change severely inhibit their practical application. Herein, a novel composite with FeSbO4-Sb2O4 hetero-nanocrystals anchored on reduced graphene oxide (rGO) sheets is designed and successfully constructed by a facile solvothermal method. The intense interaction between Fe3+ and Sb5+ oxidized from Sb3+ by graphene oxide (GO) boosts priority formation of rutile FeSbO4 nanoparticles. And the excess Sb3+ and Sb5+ subsequently generate nano-sized cervantite Sb2O4 to form FeSbO4-Sb2O4 hetero-interface. Such unique structure not only can enhance electrical conductivity and structural stability of electrode, but also shorten diffusion distance of lithium/sodium ions during discharge/charge processes. Moreover, the in-situ generated Fe during electrochemical reaction can boost lithium/sodium release from Li2O/Na2O. Attributed to the unique structure, the as-obtained FeSbO4-Sb2O4/rGO-200 electrode delivers greatly improved electrochemical performance for both lithium and sodium storage, including large reversible capacities, high rate capability, and superior long-term cycling stability. This work provides an efficient route to rationally design and synthesize hetero-structural composites boosting lithium-/sodium-storage properties.

Fast redox conversion and low shuttle effect enabled by functionalized zeolite for high-performance lithium–sulfur batteries

Lithium–sulfur (Li–S) batteries are among the most promising next-generation rechargeable battery systems because of their high theoretical energy density and low cost. Nevertheless, the notorious shuttle effect of polysulfides and poor redox kinetics significantly limit their practical applications. Herein, a metallic cobalt-doped ZSM-5 zeolite with extra-framework Li+ is constructed to inhibit the migration of polysulfides and simultaneously enhance their conversion kinetics via a separator coating strategy. The ZSM-5 zeolite possessing a sub-nanometer channel structure acts as an ionic sieve, and effectively suppresses the undesired polysulfide migration by spatial constraint. The negatively charged zeolite framework with Li+ as counterions helps to facilitate the fast Li+ transport. More importantly, Co dopants further strengthen the interaction with polysulfides and work as active sites to improve the kinetics of sulfur redox reactions, which is verified by theoretical calculations and experiments. As expected, a Li–S battery employing the modified separator delivers superior long-term cyclic stability (only 0.04% capacity decay per cycle over 500 cycles at 1.0 C) and excellent rate capability (706 mAh g−1 at 3.0 C). In addition, the stable operation of an assembled Li–S pouch cell under various bending angles demonstrates its feasibility in practical applications. This work offers a new insight into the design of advanced separator modifiers for high-performance Li–S batteries.

Eutectic-Based Polymer Electrolyte with the Enhanced Lithium Salt Dissociation for High-Performance Lithium Metal Batteries.

The deployment of lithium metal anode in solid-state batteries with polymer electrolytes has been recognized as a promising approach to achieving high-energy-density technologies. However, the practical application of the polymer electrolytes is currently constrained by various challenges, including low ionic conductivity, inadequate electrochemical window, and poor interface stability. To address these issues, a novel eutectic-based polymer electrolyte consisting of succinonitrile (SN) and poly (ethylene glycol) methyl ether acrylate (PEGMEA) is developed. The research results demonstrate that the interactions between SN and PEGMEA promote the dissociation of the lithium difluoro(oxalato) borate (LiDFOB) salt and increase the concentration of free Li+ . The well-designed eutectic-based PAN1.2 -SPE (PEGMEA: SN=1: 1.2 mass ratio) exhibits high ionic conductivity of 1.30 mS cm-1 at 30 °C and superior interface stability with Li anode. The Li/Li symmetric cell based on PAN1.2 -SPE enables long-term plating/stripping at 0.3 and 0.5 mA cm-2 , and the Li/LiFePO4 cell achieves superior long-term cycling stability (capacity retention of 80.3 % after 1500 cycles). Moreover, Li/LiFePO4 and Li/LiNi0.6 Co0.2 Mn0.2 O2 pouch cells employing PAN1.2 -SPE demonstrate excellent cycling and safety characteristics. This study presents a new pathway for designing high-performance polymer electrolytes and promotes the practical application of high-stable lithium metal batteries.

Synergistic "Anchor-Capture" Enabled by Amino and Carboxyl for Constructing Robust Interface of Zn Anode.

While the rechargeable aqueous zinc-ion batteries (AZIBs) have been recognized as one of the most viable batteries for scale-up application, the instability on Zn anode-electrolyte interface bottleneck the further development dramatically. Herein, we utilize the amino acid glycine (Gly) as an electrolyte additive to stabilize the Zn anode-electrolyte interface. The unique interfacial chemistry is facilitated by the synergistic "anchor-capture" effect of polar groups in Gly molecule, manifested by simultaneously coupling the amino to anchor on the surface of Zn anode and the carboxyl to capture Zn2+ in the local region. As such, this robust anode-electrolyte interface inhibits the disordered migration of Zn2+, and effectively suppresses both side reactions and dendrite growth. The reversibility of Zn anode achieves a significant improvement with an average Coulombic efficiency of 99.22% at 1mAcm-2 and 0.5mAhcm-2 over 500 cycles. Even at a high Zn utilization rate (depth of discharge, DODZn) of 68%, a steady cycle life up to 200h is obtained for ultrathin Zn foils (20μm). The superior rate capability and long-term cycle stability of Zn-MnO2 full cells further prove the effectiveness of Gly in stabilizing Zn anode. This work sheds light on additive designing from the specific roles of polar groups for AZIBs.

Understanding the mechanism of performance difference when substituting Al for different transition metal ions in Li-rich Mn-based cathode materials

The Al-doped modification strategy by substituting Al for different transition metal ions (TMs, TM = Mn, Ni, Co) has achieved excellent results in improving the cyclic performance of Li-rich Mn-based cathode materials (LRMs). However, the traditional explanation known as “pegging effect” is hard to distinguish how Al works in different TM substitutions. Herein, the electrochemical performances of Li1.2Mn0.52Ni0.13Co0.13Al0.02O2 (LRM-Mn), Li1.2Mn0.54Ni0.11Co0.13Al0.02O2 (LRM-Ni) and Li1.2Mn0.54Ni0.13Co0.11Al0.02O2 (LRM-Co) are studied, and LRM-Mn shows the superior long-term cycling stability, especially at the high temperature of 55 °C. Density functional theory (DFT) reveals that LRM-Mn crystal structure has higher thermodynamic stability than any other sample, which is advantageous for inhibiting the transition of LRMs to low-energy stable phases during cycling (e.g., spinel phase and rock salt phase). Combined with density of states and Bader charge analyses, we think that the increased thermodynamic stability of LRM-Mn results from the reduction of the charge transfer of Mn and Co ions in a single delithiation process, which lowers the reactivity of TMs, alleviates the Li/TM mixing and inhibits the irreversible oxygen release. In addition, the biggest volume change during the delithiation process was observed when Al was substituted for Co, which results in the materials’ premature production of fatigue stresses and intergranular cracking. This work comprehensively explains the modification mechanism of Al-doped in LRMs. It demonstrates practical significance for both the rational design of materials and the electrode electrochemical performance prediction.

Electrochemical Performance of Corn Waste Derived Carbon Electrodes Based on the Intrinsic Biomass Properties.

The exploration of cost-effective and sustainable biomass-derived carbon materials as electrodes for energy conversion and storage has gained extensive attention in recent research studies. However, the selection of the biomass and the electrochemical performance regulation of the derived biochar, as well as their interrelationship still remain challenging for practical application. Herein, corn wastes with high carbon content (>40%), corn cob and corn silk, were selected as precursors for the preparation of high value-added and high yield carbon materials via a modified synthetic process. Uniquely, this work put emphasis on the theoretical and experimental investigations of how the biomass properties influence the composition and nanostructure regulation, the electrolyte ion adsorption free energy, and the electrical conductivity of the derived carbon materials as well as their electrochemical performance optimization. Owing to the favorable specific surface area, the hierarchical porous structure, and the diverse elemental distribution, corn cob and corn silk derived carbon materials (CBC and SBC) present great potential as promising electrodes for alkaline aqueous zinc batteries and supercapacitors. The assembled CBC//Zn and SBC//Zn zinc batteries deliver high energy densities of 63.0 Wh kg-1 and 39.1 Wh kg-1 at a power density of 575 W kg-1, with excellent cycling performance of 91.1% and 84.3% capacitance retention after 10,000 cycles. As for the assembled symmetric supercapacitors, high energy densities of 14.9 Wh kg-1 and 13.6 Wh kg-1, and superior long-term cycling stability of 99.3% and 96.6% capacitance retention after 20,000 cycles could be achieved. This study highlights the advantages of utilizing corn cob and corn silk as carbon sources on the designed synthesis of carbon electrodes, and presents a meaningful perspective in the investigation of biomass-derived carbon materials and their potential applications in rechargeable devices.

Facile fabrication of ZrV2O7 nanostructures as an electrode material for supercapacitors

Energy depletion is an unavoidable reality in the twenty-first century because of the expansion of energy demands and population. In the past few decades extensive research is being focused on fabrication of novel high-performance active electrode materials for green energy storage devices. In the present work, zirconium vanadate (ZrV2O7) prepared by simple chemical route was proved to be the potential electrode material for supercapacitors (SCs). The synthesized material was analysed using different spectral as well as analytical studies. The pseudocapacitance of ZrV2O7 was evaluated by cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) and Electrochemical Impedance in an alkaline medium. ZrV2O7 delivered substantial specific capacitance (Cs) of 679 F g-1 at 5 mVs-1 and demonstrated a superior long-term cyclic stability, with Cs retention of 92.5% even after 3000 GCD cycles with 87% of coulombic efficiency. These findings substantiate the suitability of ZrV2O7 as alternate material for energy storage systems.

Cobalt Oxide Arrays Anchored to Copper Foam as Efficient Binder-free Anode for Lithium Ion Batteries.

The development of lithium-ion batteries with simplified assembling steps and fast charge capability is crucial for current battery applications. In this study, we propose a simple in-situ strategy for the construction of high-dispersive cobalt oxide (CoO) nanoneedle arrays, which grow vertically on a copper foam substrate. It is demonstrated that this nanoneedle CoO electrodes provide abundant electrochemical surface area. The resulting CoO arrays directly act as binder-free anodes in lithium-ion batteries with the copper foam functioning as the current collector. The highly-dispersed feature of the nanoneedle arrays enhances the effectiveness of active materials, leading to outstanding rate capability and superior long-term cycling stability. These impressive electrochemical properties are attributed to the highly-dispersed self-standing nanoarrays, the advantages of binder-free constituent, and the high exposed surface area of the copper foam substrate compared to copper foil, which enrich active surface area and facilitate charge transfer. The proposed approach to prepare binder-free lithium-ion battery anodes streamlines the electrode fabrication steps and holds significant promise for the future development of the battery industry.

Tetraiodo nickel phthalocyanine electrocatalyst enables superior Na–Se battery performances by enhancing the utilization of Na2Se

Sodium–Selenium (Na–Se) batteries are regarded as one of the most promising alternative energy storage devices compared to their room-temperature sodium-sulfur battery counterparts. Since Selenium cathodes operate well in carbonate-based electrolytes, the solubility issue of polyselenides is no longer an issue. However, the main obstacles of Na–Se batteries remain the precipitation and reoxidation of sodium selenide (Na2Se) owing to the high energy barrier of these reactions and passivation of the electrode during cycling. Herein, we propose a tetraiodo nickel phthalocyanine (NiPc) electrocatalyst to improve the electrochemical performance of Na–Se batteries. It is demonstrated that the presence of even a small amount of NiPc improves the electrocatalytic conversion of Na2Se by lowering the decomposition energy barrier of Na2Se. The improved cell performances are verified by the decrease in reaction polarization, Tafel slope values, and the measured internal resistance of Na–Se cells in addition to the density functional theory (DFT) calculations. Consequently, the Na–Se cell with the NiPc electrocatalyst exhibited outstanding rate capability (405 mAh∙g−1 after 250 cycles at 3375 mA g−1 and superior long-term cyclic stability (563 mAh∙g−1 after 250 cycles at 675 mA g−1), which are among the most promising rate performance characteristics demonstrated in the literature.

Conductive MOF on ZIF-Derived Carbon Fibers as Superior Anode in Sodium-Ion Battery.

Superior specific capacity, high-rate capability, and long-term cycling stability are essential to anode materials in sodium-ion batteries, and conductive metal-organic frameworks (cMOF) with good electronic and ionic conductivity may satisfy these requirements. Herein, conductive neodymium cMOF (Nd-cMOF) produced in situ on the zeolitic imidazolate framework (ZIF)-derived carbon fiber (ZIF-CFs) platform is used to synthesize the Nd-cMOF/ZIF-CFs hierarchical structure. Four types of ZIFs with different pore diameters are prepared by electrospinning. In this novel structure, ZIF-CFs provide the electroconductivity, flexible porous structure, and mechanical stability, while Nd-cMOF provides the interfacial kinetic activity, electroconductivity, ample space, and volume buffer, consequently giving rise to robust structural integrity and excellent conductivity. The sodium-ion battery composed of the Nd-cMOF/ZIF-10-CFs anode has outstanding stability and electrochemical properties, such as a specific capacity of 480.5 mAh g-1 at 0.05 A g-1 as well as capacity retention of 84% after 500 cycles.

Bottom-up gas phase construction of carbon coated Fe7Se8 nanosheet/carbon nanotube hybrid as ultrastable anode material for sodium-ion half/full batteries

Transition metal selenide/carbon nanotube (TMS/CNT) composites as one important category of anode material for rechargeable alkali metal ion batteries are always troubled by the high-quality combination between active matter and inert CNT matrices. Herein, a bottom-up gas phase pyrolysis strategy is introduced to avoid the tedious and time-consuming loading process of active nanostructures. With ferrocene and selenium powders as the raw materials, a carbon coated Fe7Se8 nanosheet/carbon nanotube (Fe7Se8@C/CNT) hybrid is synthesized. The critical role of selenium in the mass growth of CNTs at low deposition temperature is demonstrated for the first time. Benefiting from the molecular-level synthesis process, the carbon coated Fe7Se8 nanosheets are uniformly anchored on CNTs, and a porous hybrid network architecture is constructed. When tested in sodium-ion batteries (SIBs), the Fe7Se8@C/CNT electrode exhibits high reversible capacity (485 mA h g−1 at 0.1 A g−1), high initial Coulombic efficiency (97.4 %), superior long-term cycling stability upon 1000 cycles and excellent rate capability (397 mA h g−1 at 10.0 A g−1). Moreover, the full cell that coupled with a Na3V2(PO4)3 cathode also retains an undiscounted long-term cycling ability and high rate performance, reflecting its great potential for practical SIBs. The detail kinetics analyses including capacitive contribution, EIS and GITT are carried out. This work provides a new avenue for developing high-performance TMS/CNT electrode materials in electrochemical energy storage applications.

A facile preparation method and proof of cycle-stability of carbon-coated metal oxide and disulfide battery materials

Constructing composites of metal oxides and disulfides with carbonaceous materials is considered a useful approach to improve their lithium-ion storage performance. However, complicated synthesis processes and high-cost carbonaceous materials usually used hinder the commercialization of such composites. Here, as an example, carbon-coated tungsten oxides and disulfides are prepared using a facile and simple method on the basis of two kinds of low-cost carbon sources (CTAB and PVP). Following our postulated synthesis route, a variety of carbon-coated WOx, WS2, as well as mixed-phase WOx-WS2 is presented. The CTAB-assisted WOx/C (c-WOx/C), WS2/C (c-WS2/C), and mixed-phase (c-WOx/C-WS2/C) electrodes exhibit outstanding capacity retention of 74%, 99%, and 95%, respectively, which still have 420 mAh g−1, 460 mAh g−1, and 525 mAh g−1 capacity left after 200 cycles at 100 mA g−1. Particularly, the c-WS2/C electrode exhibits superior long-term cycle stability of 97% retention after 500 cycles. Similarly, the PVP-assisted WS2/C (p-WS2/C) electrode displays a capacity retention of 80% after 500 cycles. This work provides an easy and versatile route to fabricate carbon-coated tungsten oxides and disulfides with compelling battery performance and can be easily implemented for other metal oxides and disulfides.

Flexible core-shell PAN/CNTs@PVDF-HFP/Uio-66-NH2 hybrid nanofibers membrane for advanced lithium-ion batteries separator

Flexible core-shell polyacrylonitrile (PAN)/carbon nanotubes (CNTs)@Poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP)/Uio-66-NH2 (PC@PU) hybrid nanofiber membrane was prepared by coaxial electrospinning technology. PAN polymer and CNTs particles were used as core to improve the membrane structure stability for further ensuring the thermal stability of the separator. PVDF-HFP and Uio-66-NH2 nanoparticles were applied to reinforce the affinity of separator to electrolyte. The PC@PU composite membrane delivered high thermal stability and fantastic electrolyte affinity (545.76%). Furthermore, compared with Celgard 2325 commercial membrane, the PC@PU composite membrane exhibited higher porosity (80.22%) and higher Li+ conductivity (3.43 mS/cm), leading to superior rate performance and long-term cycle stability. The cell with the PC@PU hybrid membrane displayed high specific capacity of 143 mAh/g at 1C and only 0.0259% capacity attenuation of each cycle after 1000 cycles. In addition, the PC@PU composite membrane demonstrated remarkable flexibility, and the cells with bent separators exhibited outstanding electrochemical performance. Hence, the PC@PU hybrid nanofiber membrane can pave a way for the further application in the field of secondary batteries separator.

Manipulating Molecular Structure to Trigger Ultrafast and Long-Life Potassium Storage of Fe0.4 Ni0.6 S Solid Solution.

Currently, the main obstacle to the widespread utilization of metal chalcogenides (MSx ) as anode for potassium-ion batteries (PIBs) is their poor rate capability and inferior cycling stability as a result of the undesirable electrical conductivity and severe pulverization of the nanostructure during large K-ions intercalation-extraction processes. Herein, an ultrafast and long-life potassium storage of metal chalcogenide is rationally demonstrated by employing Fe0.4 Ni0.6 S solid-solution (FNS/C) through molecular structure engineering. Benefiting from improved electroactivity and intense interactions within the unique solid solution phase, the electrical conductivity and structure durability of Fe0.4 Ni0.6 S are vastly improved. As anticipated, the FNS/C electrode delivers superior rate properties (538.7 and 210.5 mAh g-1 at 0.1 and 10 A g-1 , respectively) and long-term cycle stability (180.8 mAh g-1 at 5 A g-1 after 2000 cycles with a capacity decay of 0.011% per cycle). Moreover, the potassium storage mechanisms of Fe0.4 Ni0.6 S solid solution are comprehensively revealed by several in situ characterizations and theoretical calculations. This innovative molecular structure engineering strategy opens avenues to achieve high-quality metal chalcogenides for future advanced PIBs.

Application of purified kish flake graphite as a potential cathode material for high-performance aluminum ion batteries

The separation and purification of kish graphite is an important prerequisite for its high value and comprehensive utilization. The comprehensive separation process including water washing dust removal, magnetic separation and acid leaching purification can effectively enrich and purify kish flake graphite (KFG) from low-cost industrial by-product kish graphite. When the magnetic strength is 2000 Gauss, the purified KFG has suitable recovery (57.34%), high fixed carbon content (99.38%) and low ash content (0.62%). Compared with natural flake graphite, KFG has a highly ordered graphite microcrystalline layer structure with higher graphitization degree (99.77%) and well-developed micro/nanopore with larger specific surface area (4.12 m2·g−1). Such distinctive microstructure features ensure KFG to be applied as a cathode material for aluminum ion batteries (AIBs) to exhibit superior electrochemical behaviors. KFG exhibits a high reversible specific capacity (110.7 mAh/g at 50 mA/g), outstanding rate capability (56.9 and 26.6 mAh/g at high current densities of 1000 and 2000 mA/g) and superior long-term cycling stability (101.8 mAh/g with a Coulombic efficiency of 99.5% at 1000 mA/g after 2000 cycles). This study demonstrates a promising feasibility for mass production of KFG from industrial by-product kish graphite for high performance AIBs.

Tailoring porous three-dimensional (Co,Mn)(Co,Mn)2O4/PPy architecture towards high-performance cathode for aqueous zinc-ion batteries

Aqueous zinc-ion batteries (AZIBs) have gained extensive interest due to their cost-effective and safe nature. Nonetheless, the long-term performance of AZIBs is restricted by the conductivity and structural stability of cathode materials. Herein, the porous (Co,Mn)(Co,Mn)2O4/PPy (CMO@PPy) core–shell microspheres have been favorably synthesized using a facile solvothermal method followed by a self-polymerization process. The porous structure endows CMO@PPy with more active sites which can facilitate ion and electrolyte diffusion. And PPy as coating layers not only improve the conductivity but also buffer the structural strain of cathode material, as well as inhibit the dissolution of Mn2+. Additionally, the core–shell nanostructure can effectively release the volume expansion of cathode during the cycling process. Benefitting from the unique structure, the CMO@PPy cathode delivers a high capacity of 305.2 mAh g−1 at 0.1 A g−1 and superior long-term cycling stability (90.8 mAh g−1 at 1 A g−1 after 1000 cycles with a decay of only 0.037% per cycle). Also, the enhanced electrochemical kinetic of CMO@PPy is evaluated by Galvanostatic intermittent titration technique. Additionally, the assembled flexible ZIBs demonstrate stable electrochemical properties at different bending states, indicating their potential practical applications.