Superior Long-term Cycling Stability Research Articles

A family of dual-anion-based sodium superionic conductors for all-solid-state sodium-ion batteries.

The sodium (Na) superionic conductor is a key component that could revolutionize the energy density and safety of conventional Na-ion batteries. However, existing Na superionic conductors are primarily based on a single-anion framework, each presenting inherent advantages and disadvantages. Here we introduce a family of amorphous Na-ion conductors (Na2O2-MCly, M = Hf, Zr and Ta) based on the dual-anion framework of oxychloride. Benefiting from a dual-anion chemistry and with the resulting distinctive structures, Na2O2-MCly electrolytes exhibit room-temperature ionic conductivities up to 2.0 mS cm-1, wide electrochemical stability windows and desirable mechanical properties. All-solid-state Na-ion batteries incorporating amorphous Na2O2-HfCl4 electrolyte and a Na0.85Mn0.5Ni0.4Fe0.1O2 cathode exhibit a superior rate capability and long-term cycle stability, with 78% capacity retention after 700 cycles under 0.2 C (1C = 120 mA g-1) at room temperature. The discoveries in this work could trigger a new wave of enthusiasm for exploring new superionic conductors beyond those based on a single-anion framework.

Sodium Octahydridotriborate as a Solid Electrolyte with Excellent Stability Against Sodium-Metal Anode.

Solid-state sodium metal batteries have been extensively investigated because of their potential to improve safety, cost-effectiveness, and energy density. The development of such batteries urgently required a solid-state electrolyte with fast Na-ion conduction and favorable interfacial compatibility. Herein, the progress on developing the NaB3H8 solid-state electrolytes is reported, which show a liquid-like ionic conductivity of 0.05 S cm-1 at 56°C with an activation energy of 0.35eV after an order-disorder phase transformation, matching or surpassing the best single-anion hydridoborate conductors investigated up to now. The steady polarization voltage and significantly decreased resistance are achieved in the symmetric Na/NaB3H8/Na cell, indicating the great electrochemical stability and favorable interfacial contact with the Na metal of NaB3H8. Furthermore, a Na/NaB3H8/TiS2 battery, the first high-rate (up to 1C) solid-state sodium metal battery using the single-anion hydridoborate electrolyte, is demonstrated, which exhibits superior rate capability (168.2 mAh g-1 at 0.1 C and 141.2 mAh g-1 at 1 C) and long-term cycling stability (70.9% capacity retention at 1 C after 300 cycles) at 30°C. This work may present a new possibility to solve the interfacial limitations and find a new group of solid-state electrolytes for high-performance sodium metal batteries.

Research on Fe doping regulation of vanadium-based phosphate material K3V3-xFex(PO4)4/C for potassium-ion battery cathodes

K3V3(PO4)4(KVP), a novel cathode material for potassium-ion batteries (KIBs), is recognized for its stable crystal structure and robust cycling performance. Despite these attributes, it is hampered by poor electronic conductivity and limited rate capability. In this research, Fe3+ has been substituted for a portion of V3+ to modulate the electronic structure of K3V3-xFex(PO4)4/C, aimed at enhancing its electrochemical performance. Theoretical calculations expectedly show that Fe doping at the V site reduces the band gap energy from 2.674 eV to 1.92 eV, thereby improving electron transfer. Both physical and chemical analyses confirm the successful integration of Fe3+ into the crystal structure and the adjustment of relevant lattice parameters. Additionally, Fe serves as an effective catalyst, enhancing the graphitization of the carbon coating. SEM demonstrates that Fe3+ doping encourages the development of a porous structure, which not only promotes electrolyte penetration but also provides a buffer to the crystal framework during K+ deintercalation. K3V3-xFex(PO4)4/C, when doped with Fe3+, shows superior discharge capacity and long-term cycling stability compared to KVP/C. Specifically, K3V2.8Fe0.2(PO4)4/C, with an Fe3+ doping level of x=0.2, exhibits minimal electrode polarization and outstanding rate performance. After 380 cycles at 400 mA·g−1, it maintains a discharge capacity of 46 mAh·g−1, significantly surpassing KVP/C. These findings offer valuable insights into the commercial synthesis of scalable, high-performance rechargeable KIBs cathode materials.

Sodium storage performance and mechanism of amorphous FePO4/rGO nanocomposite as a novel anode material for sodium ion batteries

Exploring novel and cost-effective anode materials is highly desired for the development of sodium-ion batteries (SIBs). Herein, an amorphous FePO4/reduced graphene oxide (FP-G) composite is prepared by a simple chemical precipitation method with leaching liquor of jarosite residue as Fe source. When used as a novel anode material for SIBs, this FP-G composite exhibits a high sodium storage activity (341.6 mAh g−1 after 100 cycles at 0.2 A g−1), superior long-term cycling stability (215.8 mAh g−1 after 1500 cycles at 0.5 A g−1), and outstanding high-rate capability (190.8 mAh g−1 at 5.0 A g−1). The FP-G composite shows a significant pseudocapacitance behavior and good electrochemical reversibility during discharge and charge processes. This work proposes a simple, feasible, and cost-effective strategy for the high-valued utilization of jarosite residue, and deeply investigates the sodium storage mechanism and potential value of FP-G composite as a novel anode material for SIBs.

Vanadium Molybdenum Disulfide Nanosheets Anchoring on Carbon Cloth as High-Energy Density Cathode for Magnesium-Lithium Hybrid Batteries.

Magnesium-lithium-ion hybrid batteries (MLIBs) have gained significant attention since the combination of a dendrite-free and low-cost magnesium anode with lithium-ion storage cathodes. However, the lack of high-performance cathodes has severely hindered their development, limited by the lower operating voltages of electrolytes. Herein, vanadium molybdenum disulfide nanosheets anchoring on flexible carbon cloth (VMS@CC) are constructed as high-performance cathodes for MLIBs, which inherit the electrochemical properties of high-voltage VS2 and high-capacity MoS2, simultaneously. By adjusting the V and Mo atomic ratio, the VMS@CC cathode for MLIBs delivers a record maximum energy density of 275.5 Wh kg-1 with a high working voltage of 1.07 V at 50 mA g-1. Meanwhile, under the synergistic effects of the conductive carbon cloth matrix, abundant hetero-interfaces and defects, as well as expanded interlayer spacing, the VMS@CC cathode displays superior rate capability and long-term cycling stability. Ex situ analyses demonstrate the VMS nanosheets cathode exhibits a Li+/Mg2+ co-insertion/extraction mechanism in MLIBs, following the in situ insertion of organic species in the hybrid electrolyte during the aging process. The fabricated flexible cathode herein provides a new insight into the construction of high-energy density cathodes for MLIBs.

Co-CoSe heterogeneous fibers with strong interfacial built-in electric field as bifunctional electrocatalyst for high-performance Zn-air battery

The explorations of efficient electrocatalysts to accelerate oxygen reactions in a wide temperature range is a crucial issue to the development of zinc-air batteries (ZAB) for all-climate applications. Herein, the Co-CoSe heterogeneous furry fibers (Co-CoSe@NHF) are developed as a bifunctional oxygen electrocatalyst for ZAB towards wide-temperature range applications. The Co-CoSe heterostructure with large work function difference (ΔWF) endows interfacial electron redistribution, which builds strong interfacial built-in electric field (BIEF) and improves the oxygen reactions. Meanwhile, the Co-CoSe heterostructure is encapsulated by in-situ grown carbon nanotubes, and forms the hollow fiber (NHF) with furry surface and beads-on-string configuration. The highly porous and conductive NHF configuration facilitates the fast kinetics and favors to accommodates volume change during cycling. As a result, the Co-CoSe@NHF achieves the superior bifunctional properties and good reliability for oxygen reactions. Integrated with the Co-CoSe@NHF fiber, the ZAB cell delivers the superior power density (301 mW cm−2) and long-term cycling stability over 280 h at 25 °C, and maintains the power densities of 126 mW cm−2 even the temperature decreases to −25 °C. Moreover, the solid-state ZAB exhibits significant flexibility and superior properties in a wide temperature range. Therefore, this work not only proposes a new strategy to design the high-performance bifunctional electrocatalysts, but also propels the development of flexible power sources for all-climate applications.

Coupling bimetallic selenides with homogeneous mediators synergistically accelerating overall sulfur redox kinetics for high-performances lithium–sulfur batteries

The practical applications of lithium-sulfur batteries (LSBs) are hampered by poor electrical conductivity, severe shuttling of intermediate lithium polysulfides (LiPSs) and sluggish redox kinetics. Herein, we introduce a multifunctional catalytic system by integrating bimetallic ZnSe-CoSe2 with CoCp2 mediators, aimed at serving as redox kinetic accelerators in LSBs. In this design, the ZnSe-CoSe2 heterostructure with hierarchical pores and large surface area, is capable of immobilizing both soluble LiPSs and CoCp2 mediators, but also provides abundant active sites for catalyzing LiPSs conversions. Concurrently, the soluble CoCp2 mediators contribute to promoting the high-dimensional growth of Li2S and reducing the interface polarization. Electrochemical experiments and theoretical analyses reveal that the ZnSe-CoSe2/CoCp2 system synergistically accelerates overall sulfur redox kinetics. Consequently, the cell with the ZnSe-CoSe2/CoCp2 system under a sulfur loading of 2.3 mg cm−2 exhibits superior long-term cycling stability at 1.0C. Additionally, it achieves a remarkable areal capacity of 6.5 mAh cm−2 under a high sulfur loading of 8.0 mg cm−2 and a low electrolyte-to-sulfur ratio of 5.0 µL mg−1.

Interacted Ternary Component Ensuring High-Security Eutectic Electrolyte for High Performance Sodium-Metal Batteries.

Due to the intrinsic flame-retardant, eutectic electrolytes are considered a promising candidate for sodium-metal batteries (SMBs). However, the high viscosity and ruinous side reaction with Na metal anode greatly hinder their further development. Herein, based on the Lewis acid-base theory, a new eutectic electrolyte (EE) composed of sodium bis(trifluoromethanesulfonyl)imide (NaTFSI), succinonitrile (SN), and fluoroethylene carbonate (FEC) is reported. As a strong Lewis base, the ─C≡N group of SN can effectively weaken the interaction between Na+ and TFSI-, achieving the dynamic equilibrium and reducing the viscosity of EE. Moreover, the FEC additive shows a low energy level to construct thicker and denser solid electrolyte interphase (SEI) on the Na metal surface, which can effectively eliminate the side reaction between EE and Na metal anode. Therefore, EE-1:6+5% FEC shows high ionic conductivity (2.62mScm-1) and ultra-high transference number of Na+ (0.96). The Na||Na symmetric cell achieves stable Na plating/stripping for 1100h and Na||Na3V2(PO4)3/C cell shows superior long-term cycling stability over 2000 cycles (99.1% retention) at 5C. More importantly, the Na||NVP/C pouch cell demonstrates good cycling performance of 102.1mAhg-1 after 135 cycles at 0.5C with an average coulombic efficiency of 99.63%.

CoS2/carbon network flexible film with Co-N bond/π-π interaction enables superior mechanical properties and high-rate sodium ion storage

Flexible electrodes based on conversion-type materials have potential applications in low-cost and high-performance flexible sodium-ion batteries (FSIBs), owing to their high theoretical capacity and appropriate sodiation potential. However, they suffer from flexible electrodes with poor mechanical properties and sluggish reaction kinetics. In this study, freestanding CoS2 nanoparticles coupled with graphene oxides and carbon nanotubes (CoS2/GO/CNTs) flexible films with robust and interconnected architectures were successfully synthesized. CoS2/GO/CNTs flexible film displays high electronic conductivity and superior mechanical properties (average tensile strength of 21.27 MPa and average toughness of 393.18 KJ m−3) owing to the defect bridge for electron transfer and the formation of the π–π interactions between CNTs and GO. In addition, the close contact between the CoS2 nanoparticles and carbon networks enabled by the Co-N chemical bond prevents the self-aggregation of the CoS2 nanoparticles. As a result, the CoS2/GO/CNTs flexible film delivered superior rate capability (213.5 mAh g−1 at 6 A g−1, better than most reported flexible anode) and long-term cycling stability. Moreover, the conversion reaction that occurred in the CoS2/GO/CNTs flexible film exhibited pseudocapacitive behavior. This study provides meaningful insights into the development of flexible electrodes with superior mechanical properties and electrochemical performance for energy storage.

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.