Active Material Research Articles

Rational Design of Electrolyte Additives for Improved Solid Electrolyte Interphase Formation on Graphite Anodes: A Study of 1,3,6-Hexanetrinitrile

The construction of a thin, uniform, and robust solid electrolyte interphase (SEI) film on the surface of active materials is pivotal for enhancing the overall performance of lithium-ion batteries (LiBs). However, conventional electrolytes often fail to achieve the desired SEI characteristics. In this work, we introduced 1,3,6-hexanetrinitrile (HTCN) in the baseline electrolyte (BE) of 1.0 M LiPF6 in Ethylene Carbonate/Dimethyl Carbonate (EC/DMC) (3:7 by volume) with 5 wt.% fluoroethylene carbonate (FEC), denoted as BE-FH. By systematically investigating the influence of FEC: HTCN weight ratios on the electrochemical performance of graphite anodes, we identified an optimal composition (FEC:HTCN = 5:4 by weight, denoted as BE-FH54) that demonstrated greatly improved initial Coulombic efficiency, rate capability, and cycling stability compared with the baseline electrolyte. Deviations from the optimal FEC:HTCN ratio resulted in the formation of either small cracks or excessively thick SEI layers. The enhanced performance of BE-FH54-based LiB is mainly ascribed to the synergistic effect of FEC and HTCN in forming a robust, thin, homogeneous, and ion-conducting SEI. This research highlights the importance of rational electrolyte design in enhancing the electrochemical performance of graphite anodes in LiBs and provides insights into the role of nitrile-based additives in modulating the SEI properties.

Synergistic effect between S and Te enhancing the electrochemical behavior of heteroatomic TeS-x cathodes in aqueous Zn–TeS batteries

Aqueous Zn–S batteries (AZSBs) have garnered increasing attention in the energy storage field owing to their high capacity, energy density, and cost effectiveness. Nevertheless, sulfur (S) cathodes face challenges, primarily stemming from sluggish reaction kinetics and the formation of an irreversible byproduct (SO42−) during the charge, hindering the progress of AZSBs. Herein, Te–S bonds within S-based cathodes were introduced to enhance electron and ion transport and facilitate the conversion reaction from zinc sulfide (ZnS) to S. This was achieved by constructing heteroatomic TeS-x@Ketjen black composite cathodes (HM-TeS-x@KB, where x = 36, 9, and 4). The HM-TeS-9@KB electrode exhibits long-term cycling stability, maintaining a capacity decay rate of 0.1 % per cycle over 450 cycles at a current density of 10 A g−1. Crucially, through a combination of experimental data analysis and theoretical calculations, the impact mechanism of Te on the charge and discharge of S active materials within the HM-TeS-9@KB cathode in AZSBs was investigated. The presence of Te–S bonds boost the intrinsic conductivity and wettability of the HM-TeS-9@KB cathode. Furthermore, during the charge, the interaction of preferentially oxidized Te with S atoms within ZnS promotes the oxidation reaction from ZnS to S and suppresses the irreversible side reaction between ZnS and H2O. These findings indicate that the heteroatomization of chalcogen S molecules represents a promising approach for enhancing the electrochemical performance of S cathodes in AZSBs.

Exploiting Mixed Valence Charge Transfer for Electrochromic and Electrofluorochromic Use.

An asymmetric mixed valence fluorophore with two different electron rich termini was investigated as a dual-role active material for electrochromism and electrofluorochromism. The fluorescence quantum yield (Φfl) and emission wavelength of the fluorophore were dependent on solvent polarity. The quantum yield of the material in an electrolyte gel, on a glass substrate and in a device was 40 %, 20 % and 13 % respectively. The fluorophore further underwent two near-simultaneous electrochemical oxidations. The first oxidation resulted in a 1000 nm red shift in the absorption to broadly absorb in the NIR, corresponding to the intervalence charge transfer (IVCT). Whereas the second oxidation led to a perceived green color at 715 nm with the extinction of the NIR absorbing IVCT. Owing to the dissymmetry of the fluorophore along with its two unique oxidation sites, the IVCT gives rise to a mixed valence transfer charge (MVCT). The coloration efficiency of the fluorophore in both solution and a device was 1433 and 200 cm2 C-1, respectively. The fluorescence intensity could be reversibly modulated electrochemically. The photoemission intensity of the fluorophore was modulated with applied potential in an operating electrochromic/electrofluorochromic device. Both the dual electrochromic and the electrofluorochromic behavior of the fluorophore were demonstrated.

Ultra–thin ePTFE–enforced electrolyte and electrolyte–electrode(s) assembly for high–performance solid–state lithium batteries

Challenges including low stability, excessive thickness, a low ionic conductivity of current solid–state electrolytes, and large interfacial resistance in solid–state lithium batteries (SSLBs) hinder their application. Herein, an ultra–thin electrolyte (∼20 μm) was prepared by using expanded porous polytetrafluoroethylene (ePTFE) as a framework and filling the pores with a hybrid electrolyte; it exhibited a high stability, mechanical strength, flexibility, and ionic conductivity (0.27 mS cm−1). A new mechanism for fast lithium-ion conduction in the composite electrolyte was creatively proposed, whereby the interface orients and concentrates lithium ions to accelerate ion transport. An electrolyte–electrode(s) assembly (EEA) was developed by directly spraying active material(s) with highly dispersed electrolytes on the electrolyte. EEA–based copper– and aluminum–free SSLBs with or without a low-dose liquid electrolyte achieved an excellent performance at room temperature. Furthermore, EEA–series–connected pouch batteries demonstrated high voltage, safety, and performance, making our ultra–thin electrolyte and EEA promising for the development of SSLBs.

A Multifunctional Secondary Based on Heterogeneous Co-MnO@NC for Depth-Induced Deposition and Conversion of Polysulfides in Li─S Batteries.

The conductive carbon-based interlayer, as the secondary current collector in the self-dissolving battery system, can effectively capture escaping cathode active materials, inducing deep release of remaining capacity. In the multi-step reactions of Li─S batteries, the environmental tolerance of the conductive carbon-based interlayer to polysulfides determines the inhibition of shuttle effects. Here, a modified metal-organic framework (Mn-ZIF67) is utilized to obtain nitrogen-doped carbon-coated heterogeneous Co-MnO (Co-MnO@NC) with dual catalytic center for the functional interlayer materials. The synergistic coupling mechanism of NC and Co-MnO achieves rapid deposition and conversion of free polysulfide and fragmented active sulfur on the secondary current collector, reducing capacity loss in the cathode. The Li─S battery with Co-MnO@NC/PP separator maintains an initial capacity of 1050mAhg-1 (3C) and excellent cycle stability (0.056% capacity decay rate). Under extreme testing conditions (S load = 5.82mgcm-2, E/S=9.1µLmg-1), a reversible capacity of 501.36mAhg-1 is observed after 200 cycles at 0.2C, showing good further practical reliability. This work demonstrates the advancement application of Co-MnO@NC bimetallic heterojunctions catalysts in the secondary current collector for high-performance Li─S batteries, thereby providing guidance for the development of interlayer in various dissolution systems.

High-Voltage Long-Cycling All-Solid-State Lithium Batteries with High-Valent-Element-Doped Halide Electrolytes.

All-solid-state batteries (ASSBs) have garnered considerable attention as promising candidates for next-generation energy storage systems due to their potentially simultaneously enhanced safety capacities and improved energy densities. However, the solid future still calls for materials with high ionic conductivity, electrochemical stability, and favorable interfacial compatibility. In this study, we present a series of halide solid-state electrolytes (SSEs) utilizing a doping strategy with highly valent elements, demonstrating an outstanding combination of enhanced ionic conductivity and oxidation stability. Among these, Li2.6In0.8Ta0.2Cl6 emerges as the standout performer, displaying a superionic conductivity of up to 4.47 mS cm-1 at 30 °C, along with a low activation energy barrier of 0.321 eV for Li+ migration. Additionally, it showcases an extensive oxidation onset of up to 5.13 V (vs Li+/Li), enabling high-voltage ASSBs with promising cycling performance. Particularly noteworthy are the ASSBs employing LiCoO2 cathode materials, which exhibit an extended cyclability of over 1400 cycles, with 70% capacity retention under 4.6 V (vs Li+/Li), and a capacity of up to 135 mA h g-1 at a 4 C rate, with the loading of active materials at 7.52 mg cm-2. This study demonstrates a feasible approach to designing desirable SSEs for energy-dense, highly stable ASSBs.

Pb/(Ni@RC) composite derived from rice for lead carbon batteries: excellent conductivity, mass transfer, and reactivity

Enhancing electron/ion transfer and suppressing the hydrogen evolution reaction (HER) represent key objectives in the quest for carbonaceous additives in lead carbon batteries. In this study, we synthesize a porous cellular carbon structure comprising cross-linked nano carbon sheets through a straightforward process involving the expansion and carbonization of rice. Furthermore, by leveraging the distinct reactions of metal oxides and carbon at elevated temperatures, we achieve the simultaneous uniform in-situ loading and embedding of Pb/Ni bimetallic nanoparticles in Pb/(Ni@RC). The etching and embedding of Ni nanoparticles result in remarkable conductivity and the development of an open pore structure. Meanwhile, the incorporation of Pb nanoparticles ensures a low HER rate and a favorable affinity for the anode active material. This positive synergistic mechanism endows Pb/(Ni@RC) with abundant redox-active sites, and mitigates the performance degradation caused by water loss and the disruption of the lead carbon binary phase. Notably, the designed anode demonstrates a high reversible capacity (170 mAh g−1), an exceptionally long cycle life (16830 cycles) under high rate partial state of charge conditions, and an enhanced capacity retention rate (85%) during partial state of charge operation.

CuGaS2@NH2-MIL-125(Ti) nanocomposite: Unveiling a promising catalyst for photocatalytic hydrogen generation

The development of efficient nanocomposites represents a promising strategy for enhancing the transfer and separation of photogenerated carriers within metal-organic frameworks (MOFs) for photocatalytic H2 generation. In this study, we report, for the first time, the successful fabrication of a novel CuGaS2@NH2-MIL-125(Ti) nanocomposite in a two-step synthesis, consisting of octahedral NH2-MIL-125(Ti) metal-organic frameworks interspersed with flat hexagonal plates of CuGaS2. The CuGaS2@NH2-MIL-125(Ti) nanocomposite effectively mitigates the recombination rate of photogenerated electron-hole pairs. Notably, the most active CuGaS2@NH2-MIL-125(Ti) composite (containing 30 wt% CuGaS2) achieves a remarkable hydrogen generation rate of 965.07 μmol/gcat, surpassing the performance of NH2-MIL-125(Ti) and CuGaS2 by approximately 83 and 144 times, respectively. Additionally, the apparent quantum efficiency for the most active material at a wavelength of 380 nm is 9.07%. This study provides valuable insights into the design of efficient I-III-VI2 compound-MOF nanocomposites for H2 generation applications.

Development of solid-state hybrid capacitor using carbon nanotube film as current collector

Structural energy-storage devices are receiving considerable attention because they can simultaneously store electrical energy and provide structural support, thereby offering high volumetric and gravimetric capacities. Although carbon fiber–based materials have been the most popular choice for current collectors, their conductivity and specific surface area are relatively low; this limits the ability to load other active materials on to the current collector. Carbon nanotube (CNT) fiber is a promising alternative for lightweight structural materials because it has a density of less than 1 g cm−3 as well as high strength and electrical conductivity. In this study, we produced a light, strong, and porous CNT film (CNTF) via direct spinning for use as a current collector. The CNTF exhibited a high specific strength compared with Al foil. We also created an activated carbon–lithium titanium oxide hybrid capacitor with the CNTF current collector, which achieved a capacity similar to that of a capacitor having an Al current collector. Furthermore, a planar pouch cell created using a solid polymer electrolyte achieved a capacity of 74.1 mAh g−1, which is comparable to that of coin cells. Thus, our findings highlight the feasibility of CNTF as a material for current collectors and provide a foundation to develop manufacturing processes for structural batteries.

Solar light assisted enhanced photocatalytic activity of smart ternary ZnO:TiO2:SnO2 nanocomposites

In the present study, the smart combinations of metal oxide semiconductors (ZnO:TiO2)1-x(SnO2)x (ZTS) with different SnO2 loadings (as x = 0.0, 0.30, 0.25, 0.20, coded as ZTS0, ZTS1, ZTS2, and ZTS3) were synthesized by employing the simple sol-gel technique. The structural, morphological, optical properties and elemental composition were analyzed by using XRD, Raman spectroscopy, FE-SEM, BET, UV–Vis spectroscopy, IC-PMS, XPS and FTIR of ZTS nanocomposite and proved the formation of smart ternary combination of nanocomposites. Systematic investigation through the characterization emphasised that the acute interfacial combination was established between metal oxide semiconductors. The crystallite size was decreased on adding the amount of SnO2 in the pristine ZTS0 nanocomposites from 23.5 nm to 10.5 nm which was confirmed by Scherrer's equation. The optical energy band gap of the obtained ZTS nanocomposites was found to vary from 3.23 to 3.34 eV on adding the amount of SnO2. The performance of the ZTS nanocomposites as photocatalyst was examined towards organic dyes and the results shows highest degradation of MB and MO dyes with ZTS3 achieving 99 % and 97.3 % degradation efficiency with 1 g/L loading dose. The plausible mechanism was suggested considering the visible light absorption spectra and band diagram resulting in supressed of the recombination rate of charge carriers. The smart combination of ZTS nanocomposites makes it an ideal material for excellent photocatalytic activity for degrading organic contaminants in presence of solar light irradiation.

Failure mechanism of 18650 Li-ion batteries induced by the heating accumulation of tab

Failure analysis of lithium-ion batteries is an effective way to discovery the defects and improve the reliability of batteries. Nevertheless, defects of LIBs in manufacturing process leading to failure are easily ignored in the scientific researches. This work investigates the failure mechanism of the failed 18650 Li-ion batteries pack. The combination of non-destructive test and micro-zone characterizations rapidly locate the failure position of anode tab. Results show that the poor welding technology of anode tab induces the heating accumulation. Long-term overheating causes the peeling of active materials and the close-packed of separator pores, which finally leads to the thermal runaway of the battery.

Towards a scalable production of β-Li3PS4-based all-solid-state batteries: Optimizing pressing parameters of the tape-casted solid electrolyte and composite cathode films

Pressing of all-solid-state batteries (ASSBs) components is one of the most important processes for scalable production. Henceforth, pressing parameters (pressure and temperature) for β-Li3PS4 (β-LPS) solid electrolyte (SE) separator films and LiNi0.6Co0.2Mn0.2 (NCM622)/β-LPS composite cathode films prepared by a slurry-based process were investigated and optimized. Compression of the β-LPS film at a temperature of 100 °C led to higher ionic conductivity than cold-pressed films. Raman and X-ray photoelectron spectroscopic analyses revealed no changes in the chemical nature of β-LPS material after hot pressing. Interestingly, time-of-flight secondary ion mass spectrometric (ToF-SIMS) analyses indicated a binder enrichment in the upper layers of the hot-pressed film. In a similar trend, increasing compression and temperature resulted in higher densification of NCM622/β-LPS composite cathode films. Based on galvanostatic intermittent titration technique (GITT) and electrochemical impedance spectroscopy (EIS) measurements, hot-pressed composite cathode at 200 MPa/100 °C exhibited a higher coverage percent of catholyte on cathode active material and a greater Li+ diffusion coefficient (DLi+) than cold-pressed one at 200 MPa/20 °C. Cycling tests of “Li–In│β-LPS│NCM/β-LPS” ASSBs with hot-pressed films displayed better cycling performance than that with cold-pressed ones, attributed to the higher concentration of electrochemically active NCM in close contact with β-LPS catholyte.

Active Packaging Film Developed by Incorporating Starch Aldehyde–Quercetin Conjugate into SPI Matrix

In this study, soy protein isolate (SPI) films incorporating quercetin-grafted dialdehyde starch (DAS-QR) and DAS/QR, respectively, were developed. The structural, physical, and functional properties of the composite films were determined. The results suggested that DAS-QR and DAS/QR formed hydrogen bonding with the SPI matrix, which improved the structural properties of the films. The light-blocking capacity, thermal stability, hydrophobicity, tensile strength, elongation at break, and antioxidant and antibacterial abilities of SPI films were improved by DAS-QR and DAS/QR. Notably, SPI films incorporated with DAS-QR exhibited better performance than those with DAS/QR in terms of antioxidant (SPI/DAS-QR: 79.8% of DPPH and 62.1% of ABTS scavenging activity; SPI/DAS/QR: 71.4% of DPPH and 56.0% of ABTS scavenging activity) and antibacterial abilities against S. aureus (inhibition rate: 92.7% for SPI/DAS-QR, 83.4% for SPI/DAS/QR). The composite coating film SPI/DAS-QR effectively maintained appearance quality, delayed the loss of weight and total soluble solids, postponed malondialdehyde accumulation, and decreased peroxidase activity and microbial contamination in fresh-cut potatoes. These good performances highlight SPI/DAS-QR as a promising active packaging material for fresh-cut product preservation.

Improving Hydrogen Release From Oxygen‐Functionalized LOHC Molecules by Ru Addition to Pt/C Catalysts

AbstractBimetallic PtRu/C catalysts have been prepared by depositing Ru onto a commercial Pt/C catalyst and subsequent thermal annealing. Different Pt : Ru ratios of 1 : 1, 2 : 1, 4 : 1, 8 : 1, and 16 : 1 have been investigated with annealing temperatures of 350 and 500 °C. Using X‐ray diffraction (XRD), synchrotron powder X‐ray diffraction (SPXRD) combined with pair distribution function (PDF) analysis and scanning transmission electron microscopy with energy dispersive X‐ray spectrum imaging (STEM‐EDXS), we show that diffusion of Ru into the fcc crystal structure of the Pt nanoparticles takes place during thermal annealing. Partial segregation and the formation of Pt nanoclusters on the bimetallic surface was observed depending on the Pt : Ru ratio. The annealing process does not only cause a high Pt dispersion but also affects the electronic structure of the Pt surface by broadening the d‐band thus facilitating the product's desorption from the surface of the bimetallic particle. These beneficial effects have been exemplified for the catalytic dehydrogenation of dicyclohexylmethanol, a promising hydrogen carrier compound with 7.2 wt% hydrogen capacity. The most active catalyst material among the tested supported alloys and monometallic reference materials was Pt4Ru1/C after annealing at 500 °C, which increased the hydrogen release productivity by 65 % compared to the unmodified Pt/C catalyst.

Active Packaging Film Developed by Incorporating Starch Aldehyde–Quercetin Conjugate into SPI Matrix

In this study, soy protein isolate (SPI) films incorporating quercetin-grafted dialdehyde starch (DAS-QR) and DAS/QR, respectively, were developed. The structural, physical, and functional properties of the composite films were determined. The results suggested that DAS-QR and DAS/QR formed hydrogen bonding with the SPI matrix, which improved the structural properties of the films. The light-blocking capacity, thermal stability, hydrophobicity, tensile strength, elongation at break, and antioxidant and antibacterial abilities of SPI films were improved by DAS-QR and DAS/QR. Notably, SPI films incorporated with DAS-QR exhibited better performance than those with DAS/QR in terms of antioxidant (SPI/DAS-QR: 79.8% of DPPH and 62.1% of ABTS scavenging activity; SPI/DAS/QR: 71.4% of DPPH and 56.0% of ABTS scavenging activity) and antibacterial abilities against S. aureus (inhibition rate: 92.7% for SPI/DAS-QR, 83.4% for SPI/DAS/QR). The composite coating film SPI/DAS-QR effectively maintained appearance quality, delayed the loss of weight and total soluble solids, postponed malondialdehyde accumulation, and decreased peroxidase activity and microbial contamination in fresh-cut potatoes. These good performances highlight SPI/DAS-QR as a promising active packaging material for fresh-cut product preservation.

Preparation of chitosan/Tenebrio molitor larvae protein/curcumin active packaging film and its application in blueberry preservation

With growing concerns about postharvest spoilage of fruits, higher requirements have been placed on high-performance and sustainable active packaging materials. In this study, we prepared curcumin-based functional composite films using chitosan (CS) and Tenebrio molitor larvae protein (TMP) as the substrates. The effects of curcumin concentration on the structural and physicochemical properties of the composite films were determined. Curcumin was equally distributed in the polymer film through physical interactions. Furthermore, the curcumin composite film with 0.3 % addition exhibited a 27.39 % increase in elongation at break (EBA), a 37.04 % increase in the water vapor barrier, and strong UV-blocking properties and antioxidant activity compared with the control film (CS/TMP). The degradation experiment of the composite film on natural soil revealed that the composite film exhibited good biodegradability and environmental protection. Furthermore, the applicability of functional composite films for preserving blueberries was investigated. Compared with the control film and polyethylene (PE) films, the prepared composite films packaging treatment reduced the decay rate and weight loss rate of blueberries during storage, delayed softening and aging, and maintained the quality of blueberries. Using sustainable protein resources (TMP) and natural polysaccharides as packaging materials provides an economically, feasible and sustainable way to achieve the functional preservation of biomass materials.

Enhanced photothermoelectric conversion in self-rolled tellurium photodetector with geometry-induced energy localization

Photodetection has attracted significant attention for information transmission. While the implementation relies primarily on the photonic detectors, they are predominantly constrained by the intrinsic bandgap of active materials. On the other hand, photothermoelectric (PTE) detectors have garnered substantial research interest for their promising capabilities in broadband detection, owing to the self-driven photovoltages induced by the temperature differences. To get higher performances, it is crucial to localize light and heat energies for efficient conversion. However, there is limited research on the energy conversion in PTE detectors at micro/nano scale. In this study, we have achieved a two-order-of-magnitude enhancement in photovoltage responsivity in the self-rolled tubular tellurium (Te) photodetector with PTE effect. Under illumination, the tubular device demonstrates a maximum photovoltage responsivity of 252.13 V W−1 and a large detectivity of 1.48 × 1011Jones. We disclose the mechanism of the PTE conversion in the tubular structure with the assistance of theoretical simulation. In addition, the device exhibits excellent performances in wide-angle and polarization-dependent detection. This work presents an approach to remarkably improve the performance of photodetector by concentrating light and corresponding heat generated, and the proposed self-rolled devices thus hold remarkable promises for next-generation on-chip photodetection.

Comprehensive aging model coupling chemical and mechanical degradation mechanisms for NCM/C6-Si lithium-ion batteries

The aging of lithium-ion batteries (LIBs) is synergistically influenced by multiple chemical/mechanical degradation mechanisms. Therefore, conventional models that incorporate only partial mechanisms exhibit limited predictive accuracy and applicability, failing to fully reflect the effects of chemical/mechanical degradation under complex operating conditions. Here, we propose an aging model for NCM/C6-Si LIBs coupled with comprehensive chemical/mechanical degradation mechanisms. The model includes chemical mechanisms at the C6-Si anode solid electrolyte interface (SEI), Li plating, and NCM cathode electrolyte interface (CEI), as well as mechanical mechanisms of loss of active material (LAM) for C6, Si, and NCM. Based on this model, we comprehensively investigate the effect of capacity loss by (dis)charge rates and ambient temperatures, obtaining the aging characteristics and the contribution of each mechanism to loss under different variables. Furthermore, we quantitatively analyze the sensitivity and response characteristics of the degradation sub-mechanism to (dis)charge rate and temperature. This study introduces an advanced aging analysis model for NCM/C6-Si LIBs, which can effectively decouple the operational characteristics of the degradation mechanism and provide guidance for developing next-generation high-energy LIBs.

Cross-linkable binder for composite silicon-graphite anodes in lithium-ion batteries

Silicon (Si) is a promising substitute for graphite anode due to the high theoretical specific capacity (4200 mAh g−1). However, too large volume change exists during the lithiation/delithiation process. Composite anode, prepared by mixing Si with graphite, can realize higher specific capacity than graphite and much better cycle performance than Si anode. However, the capacity decay caused by pulverization of Si particles is still a great challenge. Here, a cross-linkable binder rich in nitrile, carboxyl and hydroxyl groups is designed for composite silicon-graphite (Si-C) anode. The nitrile and hydroxyl groups can be in situ cross-linked in the batteries through Ritter reaction. The cross-linked binder has excellent resilience and good adhesion to the active materials and current collector. The cycle performance of the cell with cross-linked binder is much better than the counterpart. Scanning electron microscopy results of the cycled Si-C anode show that the cross-linked binder can suppress the volume expansion and pulverization. Moreover, the investigation with X-ray photoelectronic spectrum and density function theory calculation demonstrate that the decomposition of ester solvent and LiPF6 on Si anode has been mitigated and more stable SEI film is formed on the Si-C anode. Our strategy of in situ cross-linking binder in the batteries has provided a feasible way for designing the next generation of silicon-based anodes with higher specific capacity and longer cycling life.

CNT Composite β-MnO2 with Fiber Cable Shape as Cathode Materials for Aqueous Zinc-Ion Batteries.

Rechargeable aqueous zinc-ion batteries (AZIBs) have developed into one of the most attractive materials for large-scale energy storage owing to their advantages such as high energy density, low cost, and environmental friendliness. Nevertheless, the sluggish diffusion kinetics and inherent impoverished conductivity affect their practical application. Herein, the β-MnO2 composited with carbon nanotubes (CNT@M) is prepared through a simple hydrothermal approach as a high-performance cathode for AZIBs. The CNT@M electrode exhibits excellent cycling stability, in which the maximum specific discharge capacity is 259 mA h g-1 at 3 A g-1, and there is still 220 mA h g-1 after 2000 cycles. The specific capacity is obviously better than that of β-MnO2 (32 mA h g-1 after 2000 cycles). The outstanding electrochemical performance of the battery is inseparable from the structural framework of CNT and inherent high conductivity. Furthermore, CNT@M can form a complex conductive network based on CNTs to provide excellent ion diffusion and charge transfer. Therefore, the active material can maintain a long-term cycle and achieve stable capacity retention. This research provides a reasonable solution for the reliable conception of Mn-based electrodes and indicates its potential application in high-performance AZIB cathode materials.