Porous ZnMn2O4 nanowires as an advanced anode material for lithium ion battery

ZnMn2O4 nanostructures: Synthesis via two different chemical methods, characterization, and photocatalytic applications for the degradation of new dyes

Water pollution have become contentious among researchers. By increasing industrialization, the availability of clean water has been reduced. Industrial dyestuffs contribute to the escalation of environmental pollution and are the largest group of organic compounds. The aim of the present work is the synthesis of nanostructures that accelerate the removal of organic dyes from water. To reach this aim, first, ZnMn2O4 nanostructures were synthesized by hydrothermal and co-precipitation methods using maleic acid and phenylalanine as a capping agent. Second, the nanostructures were characterized. XRD analysis revealed the formation of ZnMn2O4 with diameters about 32.3 nm. SEM analysis showed the formation of the agglomerated spherical ZnMn2O4 nanostructures with diameters lower than 50 nm. EDX analysis confirmed the purity of the prepared samples with the presence of Zn, Mn, and O. FT-IR analysis confirmed the bonding between Mn and O at about 620 cm-1. ZnMn2O4 nanostructures showed antiferromagnetic behaviors due to the super-exchange interactions between manganese ions. Finally, the photocatalytic behavior of the nanostructures was investigated for degradation of the anionic and cationic dyes. The results of the photocatalytic tests of two as-prepared samples via different methods were similar. The results exhibit a promising photocatalytic activity in the presence of 0.03 g photocatalyst for degradation of a dye solution with 10 ppm concentration. We introduced these conditions as optimum conditions and achieved maximum decolorization (92.43 %) in the 10 ppm of MV solution after 90 min. Also, we repeated six consecutive reaction cycles and observed a little activity loss after six reactions. We related this result to the high stability of the photocatalyst. We performed scavenging experiments to evaluate the active species involved in the photocatalytic process and plausible mechanisms. The photocatalytic degradation of MV decreased in the presence of TBA and BQ, respectively. This decrease indicated that OH° and O2°- radicals are important active species in the MV degradation process.

Enhancing lithium storage performance of bimetallic oxides anode by synergistic effects

Spinel bimetallic transition metal oxide anode such as ZnMn₂O₄, has drawn increasing interest due to attractive bimetal interaction and high theoretical capacity. While it suffers from huge volume expansion and poor ionic/electronic conductivity. Nanosizing and carbon modification can alleviate these issues, while the optimal particle size within host is unclear yet. We here propose an in-situ confinement growth strategy to fabricate pomegranate-structured ZnMn₂O₄ nanocomposite with calculated optimal particle size in mesoporous carbon host. Theoretical calculations reveal favorable interatomic interactions between the metal atoms. By the synergistic effects of structural merits and bimetal interaction, the optimal ZnMn₂O₄ composite achieves greatly improved cycling stability (811 mAh g^-1 at 0.2 A g^-1 after 100 cycles), which can maintain its structural integrity upon cycling. X-ray absorption spectroscopy analysis further confirms delithiated Mn species (Mn₂O₃ but little MnO). Briefly, this strategy brings new opportunity to ZnMn₂O₄ anode, which could be adopted to other conversion/alloying-type electrodes.

Facile Construction of Porous ZnMn2O4 Hollow Micro-Rods as Advanced Anode Material for Lithium Ion Batteries

Spinel ZnMn₂O₄ is considered a promising anode material for high-capacity Li-ion batteries due to their higher theoretical capacity than commercial graphite anode. However, the insufficient cycling and rate properties seriously limit its practical application. In this work, porous ZnMn₂O₄ hollow micro-rods (ZMO HMRs) are synthesized by a facile co-precipitation method coupled with annealing treatment. On the basis of electrochemical analyses, the as-obtained samples are first characterized by X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, and scanning electron microscopy techniques. The influences of different polyethylene glycol 400 (PEG 400) additions on the formation of the hollow rod structure are also discussed. The abundant multi-level pore structure and hollow feature of ZMO HMRs effectively alleviate the volume expansion issue, rendering abundant electroactive sites and thereby guaranteeing convenient Li⁺ diffusion. Thanks to these striking merits, the ZMO HMRs anode exhibits excellent electrochemical lithium storage performance with a reversible specific capacity of 761 mAh g^-1 at a current density of 0.1 A g^-1, and a long-cycle specific capacity of 529 mAh g^-1 after 1000 cycles at 2.0 A g^-1 and keep a remarkable rate capability. In addition, the assembled ZMO HMRs-based full cells deliver an excellent rate capacity, and when the current density returns to 0.05 A g^-1, the specific capacity can still reach 105 mAh g^-1 and remains at 101 mAh g^-1 after 70 cycles, maintaining a material-level energy density of approximately 273 Wh kg^-1. More significantly, such striking electrochemical performance highlights that porous ZMO HMRs could be a promising anode candidate material for LIBs.

Morphological and Electrochemical Properties of ZnMn2O4 Nanopowders and Their Aggregated Microspheres Prepared by Simple Spray Drying Process

Phase-pure ZnMn₂O₄ nanopowders and their aggregated microsphere powders for use as anode material in lithium-ion batteries were obtained by a simple spray drying process using zinc and manganese salts as precursors, followed by citric acid post-annealing at different temperatures. X-ray diffraction (XRD) analysis indicated that phase-pure ZnMn₂O₄ powders were obtained even at a low post-annealing temperature of 400 °C. The post-annealed powders were transformed into nanopowders by simple milling process, using agate mortar. The mean particle sizes of the ZnMn₂O₄ powders post-treated at 600 and 800 °C were found to be 43 and 85 nm, respectively, as determined by TEM observation. To provide practical utilization, the nanopowders were transformed into aggregated microspheres consisting of ZnMn₂O₄ nanoparticles by a second spray drying process. Based on the systematic analysis, the optimum post-annealing temperature required to obtain ZnMn₂O₄ nanopowders with high capacity and good cycle performance was found to be 800 °C. Moreover, aggregated ZnMn₂O₄ microsphere showed improved cycle stability. The discharge capacities of the aggregated microsphere consisting of ZnMn₂O₄ nanoparticles post-treated at 800 °C were 1235, 821, and 687 mA h g⁻¹ for the 1st, 2nd, and 100th cycles at a high current density of 2.0 A g⁻¹, respectively. The capacity retention measured after the second cycle was 84%.

The Progress of Cobalt-Based Anode Materials for Lithium Ion Batteries and Sodium Ion Batteries

Limited by the development of energy storage technology, the utilization ratio of renewable energy is still at a low level. Lithium/sodium ion batteries (LIBs/SIBs) with high-performance electrochemical performances, such as large-scale energy storage, low costs and high security, are expected to improve the above situation. Currently, developing anode materials with better electrochemical performances is the main obstacle to the development of LIBs/SIBs. Recently, a variety of studies have focused on cobalt-based anode materials applied for LIBs/SIBs, owing to their high theoretical specific capacity. This review systematically summarizes the recent status of cobalt-based anode materials in LIBs/SIBs, including Li+/Na+ storage mechanisms, preparation methods, applications and strategies to improve the electrochemical performance of cobalt-based anode materials. Furthermore, the current challenges and prospects are also discussed in this review. Benefitting from these results, cobalt-based materials can be the next-generation anode for LIBs/SIBs.

Porous quasi-graphitic carbon sheets for unprecedented sodium storage

Water-soluble KCl as the catalyst and template to produce PGC sheets in CCVD. Abundant channels on the surface of PGCs helps the transportation and diffusion of Na⁺. PGC sheets deliver a high reversible specific capacity of 237 mA h g⁻¹ at 0.1 A g⁻¹.

Scalable Synthesis of One-Dimensional Mesoporous ZnMnO3 Nanorods with Ultra-Stable and High Rate Capability for Efficient Lithium Storage

The cost-efficient ZnMnO₃ has attracted increasing attention as a prospective anode candidate for advanced lithium-ion batteries (LIBs) owing to its resourceful abundance, large lithium storage capacity and low operating voltage. However, its practical application is still seriously limited by the modest cycling and rate performances. Herein, a facile design to scalable synthesize unique one-dimensional (1D) mesoporous ZnMnO₃ nanorods (ZMO-NRs) composed of nanoscale particles (≈11 nm) is reported. The 1D mesoporous structure and nanoscale building blocks of the ZMO-NRs effectively promote the transport of ions/electrons, accommodate severe volume changes, and expose more active sites for lithium storage. Benefiting from these appealing structural merits, the obtained ZMO-NRs anode exhibits excellent rate behavior (≈454 mAh g^-1 at 2 A g^-1 ) and ultra-long term cyclic performance (≈949.7 mAh g^-1 even over 500 cycles at 0.5 A g^-1 ) for efficient lithium storage. Additionally, the LiNi_0.8 Co_0.1 Mn_0.1 O₂ //ZMO-NRs full cell presents a practical energy density (≈192.2 Wh kg^-1 ) and impressive cyclability with approximately 91 % capacity retention over 110 cycles. This highlights that the ZMO-NRs product is a highly promising high-rate and stable electrode candidate towards advanced LIBs in electronic devices and sustainable energy storage applications.

Engineering Na-Mo-O/Graphene Oxide Composites with Enhanced Electrochemical Performance for Lithium Ion Batteries

Sodium molybdate (Na−Mo−O) wrapped by graphene oxide (GO) composites have been prepared via a simple in‐situ precipitation method at room temperature. The composites are mainly constructed with one dimension (1D) ultra‐long sodium molybdate nanorods, which are wrapped by the flexible GO. The introduction of GO is expected to not merely provide more active sites for lithium‐ions storage, but also improve the charge transfer rate of the electrode. The testing electrochemical performances corroborated the standpoint: The Na−Mo−O/GO composites delivers specific capacities of 718 mAh g⁻¹ after 100 cycles at 100 mA g⁻¹, and 570 mAh g⁻¹ after 500 cycles at a high rate of 500 mA g⁻¹; for comparison, the bare Na−Mo−O nanorod shows a severe capacity decay, which deliver only 332 mAh g⁻¹ after 100 cycles at 100 mA g⁻¹. In view of the cost‐efficient and less time‐consuming in synthesis, and one‐step preparation without further treatment, these Na−Mo−O nanorods/GO composites present potential and prospective anodes for LIBs.

β-MnO2 /Metal-Organic Framework Derived Nanoporous ZnMn2 O4 Nanorods as Lithium-Ion Battery Anodes with Superior Lithium-Storage Performance

Nanoporous ZnMn₂ O₄ nanorods have been successfully synthesized by calcining β-MnO₂ /ZIF-8 precursors (ZIF-8 is a type of metal-organic framework). If measured as an anode material for lithium-ion batteries, the ZnMn₂ O₄ nanorods exhibit an initial discharge capacity of 1792 mA h g^-1 at 200 mA g^-1 , and an excellent reversible capacity of 1399.8 mA h g^-1 after 150 cycles (78.1 % retention of the initial discharge capacity). Even at 1000 mA g^-1 , the reversible capacity is still as high as 998.7 mA h g^-1 after 300 cycles. The remarkable lithium-storage performance is attributed to the one-dimensional nanoporous structure. The nanoporous architecture not only allows more lithium ions to be stored, which provides additional interfacial lithium-storage capacity, but also buffers the volume changes, to a certain degree, during the Li⁺ insertion/extraction process. The results demonstrate that nanoporous ZnMn₂ O₄ nanorods with superior lithium-storage performance have the potential to be candidates for commercial anode materials in lithium-ion batteries.

Enhanced reversible capability of a macroporous ZnMn2O4/C microsphere anode with a water-soluble binder for long-life and high-rate lithium-ion storage

ZnMn₂O₄ and carbon are mixed uniformly to form macroporous ZnMn₂O₄/C microspheres consisting of many tiny nanoparticles. The macroporous ZnMn₂O₄/C microsphere anode with a CMC binder shows superior cycle performance in lithium-ion batteries.

Mesoporous ZnMn2O4 Microtubules Derived from a Biomorphic Strategy for High-Performance Lithium/Sodium Ion Batteries

ZnMn₂O₄ microtubules (ZMO-MTs) with a mesoporous structure are fabricated by a novel yet effective biomorphic approach employing cotton fiber as a biotemplate. The fabricated ZMO-MT has approximately an inner diameter of 8.5 μm and wall thickness of 1.5 μm. Further, the sample of ZMO-MT displays a large specific surface area of 48.5 m² g^-1. When evaluated as a negative material for Li-ion batteries, ZMO-MT demonstrates an improved cyclic performance with discharge capacities of 750.4 and 535.2 mA h g^-1 after 300 cycles, under current densities of 200 and 500 mA g^-1, respectively. Meanwhile, ZMO-MT exhibits superior rate performances with high reversible discharge capacities of 614.7 and 465.2 mA h g^-1 under high rates of 1000 and 2000 mA g^-1, respectively. In sodium ion batteries applications, ZMO-MT delivers excellent high discharge capacities of 102 and 71.4 mA h g^-1 after 300 cycles under 100 and 200 mA g^-1, respectively. An excellent rate capability of 58.2 mA h g^-1 under the current density of 2000 mA g^-1 can also be achieved. The promising cycling performance and rate capability could be benefited from the unique one-dimensional mesoporous microtubular architecture of ZMO-MT, which offers a large electrolyte/electrode accessible contact area and short diffusion distance for both of ions and electrons, buffering the volume variation originated from the repeated ion intercalation/deintercalation processes.

Rice-shaped porous ZnMn2O4 microparticles as advanced anode materials for lithium-ion batteries

Novel rice-shaped porous ZnMn₂O₄ microparticles made of nanoparticles were prepared by the calcination of Zn_0.33Mn_0.67CO₃ precursors synthesized using a facile triethanolamine-assisted solvothermal method.

Electrophoretic Deposition of SnFe2O4–Graphene Hybrid Films as Anodes for Lithium Ion Batteries

Binder-free SnFe2O4–submillimetre (hundreds of micrometres)-sized reduced graphene oxide (SnFe2O4–srGO) hybrid films were synthesized through electrophoretic deposition and subsequent carbonization treatment. Scanning electron microscopy, transmission electron microscopy, and energy-dispersive X-ray spectroscopy results revealed that SnFe2O4–srGO hybrid films exhibit both horizontal and vertical channels. SnFe2O4–srGO hybrid films were used as binder-free anodes for lithium ion half-cells and revealed a high capacity of ~1018.5 mA h g−1 at 0.1 A g−1 after 200 cycles. During rate performance tests, a high capacity of 464.1 mA h g−1 (~61.2 % retention) was maintained at a current density of 4 A g−1, indicating an excellent structural stability of SnFe2O4–srGO hybrid films at high current densities.

Self-sacrificial template formation of ultrathin single-crystalline ZnMn2O4 nanoplates with enhanced Li-storage behaviors for Li-ion batteries

Ultrathin single-crystalline ZnMn₂O₄ nanoplates were first designed and tailored as an anode for advanced Li-ion batteries via an efficient self-sacrificial template synthetic strategy, and delivered excellent Li-storage performance at high C rates.