In-situ synthesis of reduced graphene oxide wrapped Mn3O4 nanocomposite as anode materials for high-performance lithium-ion batteries

We report a novel in-situ symbiosis method to prepare reduced graphene oxide wrapped Mn₃O₄ nanoparticles (rGO/Mn₃O₄) with uniform size about 50 nm as anodes for lithium-ion batteries (LIBs), which can simplify the preparation process and effectively reduce pollution. The rGO/Mn₃O₄ nanocomposite exhibited a reversible specific capacity of 795.5 mAh g^?1 at 100 mA g^?1 after 200 cycles (capacity retention: 87.4%), which benefits from the unique structural advantages and the synergistic effect of rGO and Mn₃O₄. The Mn₃O₄ nanoparticles encapsulated among the rGO nanosheets exhibited good electrochemical activity, and the multilayer wrinkled rGO sheets provided a stable 3D conduction channel for Li⁺/e^? transport. The rGO/Mn₃O₄ nanocomposite is a promising anode candidate for advanced LIBs with excellent cycling performance and rate performance. Furthermore, this new preparation method can be extended to green and economical synthesis of advanced graphene/manganese-based nanocomposites.     

Lithium storage behaviors of PbNb2O6 in rechargeable batteries

Herein, we propose a new anode material, PbNb₂O₆, for use in lithium-ion batteries. PbNb₂O₆ can be synthesized via a simple and traditional solid-state method. The as-prepared powder exhibits an average size distribution of about 0.5 μm. When tested in a lithium-ion cell, the PbNb₂O₆ electrode can exhibit a charge capacity of 245.2 mAh g⁻¹ at 200 mA g⁻¹, and after 80 cycles, the capacity can retain a charge capacity of 181.4 mAh g⁻¹, showing 0.32% capacity fading per cycle. Furthermore, the capacity of the PbNb₂O₆ electrode is 223.1 mAh g⁻¹, even when cycled at 1000 mA g⁻¹, and a capacity of 150.7 mAh g⁻¹ is maintained up to 500 cycles. In addition, the lithiation mechanism of PbNb₂O₆ is investigated via various techniques. Interestingly, PbNb₂O₆ exhibits high capacity without the contribution of two redox couples of niobium after the initial cycles. Finally, all Results suggest that PbNb₂O₆ has potential for use as an electrode in lithium-ion batteries.     

An environmentally friendly and low-cost catalyst for Li–CO2 batteries based on Co recovered from waste lithium-ion batteries

With the use of lithium batteries increasing year by year, resulting in a large number of waste lithium-ion batteries generated, bringing pressure to the ecological system while also causing a waste of Co resources. Although Co-based catalysts are also of interest in the Li–CO₂ system, no research has been reported on the preparation of catalysts for value-added utilization of recovered Co. In this paper, Li–CO₂ batteries with Co₃O₄/CNT cathodes were prepared by environmentally friendly hydrothermal method employing cobalt oxalate recycled from waste lithium-ion batteries as a Co source in combination with commercial CNT. Unlike traditional noble metal and transition metal-based catalysts, which are expensive and complicated, this work can further reduce the cost of batteries by recycling valuable Co sources from waste lithium-ion batteries. As a result, the battery has the discharge capacity of 2728 mAh g^?1 at a current density of 100 mA g^?1. Not only that, but it can reach more than 85 cycles at a limited capacity of 400 mAh g^?1.     

A novel carbon microspheres@SnO2/reduced graphene composite as anode for lithium-ion batteries with superior cycle stability

Many advantages made SnO₂ a potential anode for lithium-ion batteries, but huge volume expansion during cycling seriously impeded its practical application. Here, a novel double-carbon structure with low graphene weight proportion was successfully prepared using a facile hydrothermal method to enhance the long-cycle stability of SnO₂ as anodes for lithium-ion batteries. In this structure, SnO₂ nanoparticles were formed around the surface of the carbon microspheres (CMS), and the reduced graphene (GR) shuttled through the outer layer. As anodes for lithium-ion batteries, the SnO₂ protected by dual carbon (CMS@SnO₂/GR) exhibited outstanding cycle performance with an initial reversible capacity of 789.5 mAh g^-1 and the reversible capacity retention rate of 68.6% after 350 cycles at 200 mA g^-1. The abundance free space among CMS, nano-scale, and the excellent flexibility of graphene were all contributed to alleviating the volume variation of CMS@SnO₂/GR during the lithiation and delithiation.     

Waste catkins-derived graphitic carbon/Co3O4 composites as long-life and high-rate anodes for lithium-ion battery

Upgrading waste re-utilization has been regarded as an important concept to promote the sustainable development of social economy. Herein, waste catkins were used as carbon source and template to prepare graphitic carbon/Co₃O₄ composites through cobalt salt immersion, in-situ carbonization and calcination. The obtained Co₃O₄/C composites inherit the microtubular structure of catkins with ultra-thin tube wall and large tube cavity. Particularly, the sample (Co₃O₄/C-280) calcined at 280 °C in air shows a morphology of the hollow Co₃O₄ spheres (av. 50 nm) evenly embedded on the biocarbon tube. As an anode for lithium-ion battery, such unique structure is more conductive to alleviate volume expansion. As expected, Co₃O₄/C-280 electrode has excellent rate capability at 5 A g⁻¹ and stable long-cycle performance (647.3 mA h g⁻¹, 1800 cycles, 1 A g⁻¹). The presence of pseudo-capacitance behavior plays an important role in improving the capacity of material. The good electrochemical properties of Co₃O₄/C-280 can be ascribed to the synergistic effect of hollow tubular structure and graphitic carbon. Therefore, the strategy of making waste profitable is in line with the theme of green and sustainable development, and provides a reference for improving lithium storage performance of Co₃O₄-based anode materials.     

Molten hydroxides synthesis of hierarchical cobalt oxide nanostructure and its application as anode material for lithium ion batteries

Hierarchical Co₃O₄ nanostructure is synthesized via a self-assembled process in molten hydroxides. The morphologies, crystal structures and the phase transformation processes are analyzed by field-emission scanning electron microscopy, transmission electron microscopy, and X-ray diffraction. As an anode material for lithium ion batteries, the hierarchical Co₃O₄ exhibit an initial capacity of 1336 mAh g⁻¹ and a stable capacity of 680 mAh g⁻¹ over 50 cycles. More importantly, high rate capability is obtained at different current densities between 140 and 1120 mA g⁻¹. The improved electrochemical performance of Co₃O₄ could be attributed to the unique hierarchical nanostructure.     

Graphene aerogel encapsulated Co3O4 microcubes derived from prussian blue analog as integrated anode with enhanced Li-ion storage properties

In lithium-ion batteries (LIB), cobalt oxide is considered an ideal anode material because of its theoretical specific capacity of up to 890 mAh g⁻¹, abundant resources, and low price. However, the volume expansion during the charging and discharging process and its lower conductivity have hindered its development. In this work, a metal-organic framework (MOF) was used as an initial template, encapsulated in graphene aerogels (GA) by hydrothermal and programmed temperature-controlled annealing and eventually formed into Co₃O₄ microcubes@GA composite. GA acts as a three-dimensional conductive network and mechanical skeleton, providing high electrical conductivity and structural stability to the composites. Moreover, the precursor's high porosity and stable structure are retained after annealing treatment. As an anode, the best long cycle life of Co₃O₄ microcubes@GA was achieved when the graphene oxide (GO) concentration was 3.0 mg ml⁻¹, reaching 1234.9 mAh g⁻¹ after 200 cycles at 1 A g⁻¹ with a coulomb efficiency (CE) of 98.97%.     

CNT@TiO2 nanohybrids for high-performance anode of lithium-ion batteries

This work describes a potential anode material for lithium-ion batteries (LIBs), namely, anatase TiO₂ nanoparticle-decorated carbon nanotubes (CNTs@TiO₂). The electrochemical properties of CNTs@TiO₂ were thoroughly investigated using various electrochemical techniques, including cyclic voltammetry, electrochemical impedance spectroscopy, galvanostatic cycling, and rate experiments. It was revealed that compared with pure TiO₂ nanoparticles and CNTs alone, the CNT@TiO₂ nanohybrids offered superior rate capability and achieved better cycling performance when used as anodes of LIBs. The CNT@TiO₂ nanohybrids exhibited a cycling stability with high reversible capacity of about 190 mAh g^-1 after 120 cycles at a current density of 100 mA g^-1 and an excellent rate capability (up to 100 mAh g^-1 at a current density of 1,000 mA g^-1).     

Facile synthesis of porous hollow Co3O4 microfibers derived-from metal-organic frameworks as an advanced anode for lithium ion batteries

Co₃O₄, as a promising anode material for the next generation lithium ion batteries to replace graphite, displays high theoretical capacity (890 mAh g⁻¹) and excellent electrochemical properties. However, the drawbacks of its poor cycle performance caused by large volume changes during charge-discharge process and low initial coulombic efficiency due to large irreversible reaction impede its practical application. Herein, we have developed a porous hollow Co₃O₄ microfiber with 500 nm diameter and 60 nm wall thickness synthesized via a facile chemical precipitation method with subsequent thermal decomposition. As an advanced anode for lithium ion batteries, the porous hollow Co₃O₄ microfibers deliver an obviously enhanced electrochemical property in terms of lithium storage capacity (1177.4 mA h g⁻¹ at 100 mA g⁻¹), initial coulombic efficiency (82.9%) and cycle performance (76.6% capacity retention at 200th cycle). This enhancement could be attributed to the well-designed microstructure of porous hollow Co₃O₄ microfibers, which could increase the contact surface area between electrolyte and active materials and accommodate the volume variations via additional void space during cycling.     

Micro/nanostructured Bi2Mn4O10 with hierarchical spindle morphology as a highly efficient anode material for lithium-ion batteries

Mullite-type compound Bi₂Mn₄O₁₀ has shown the feasibility as anodes of next lithium-ion batteries (LIBs). Herein micro/nano-Bi₂Mn₄O₁₀ with hierarchical spindle-like architectures has been successfully synthesized using a one-step hydrothermal method without any no surfactant or template. A time-dependent experiment is carried out to observe the morphology evolution, suggesting a nucleation–aggregation/growth–dissolution–recrystallization process. As anode of LIBs, the as-prepared spindle-shaped micro/nano Bi₂Mn₄O₁₀ harvests a significantly high initial discharge capacity of 1022 mA h g⁻¹ at 1 C, an excellent cyclability performance (563.8 mA h g⁻¹ after 400 cycles), a better high-rate capability (100 mA h g⁻¹ at 10 C), quick diffusion kinetics (1.8 × 10⁻¹² cm² s⁻¹), and low active energy (19.5 kJ mol⁻¹), which are significantly superior to that of its bulk counterparts and the previous reports. The encouraging lithium storage performance largely stems from the synergistic effect of the unique spindle-shaped micro/nanostructure.     

Highly reversible Co3O4/graphene hybrid anode for lithium rechargeable batteries

A Co₃O₄/graphene hybrid material was fabricated using a simple in situ reduction process and demonstrated as a highly reversible anode for lithium rechargeable batteries. The hybrid is composed of 5 nm size Co₃O₄ particles uniformly dispersed on graphene, as observed by transmission electron microscopy, atomic force microscopy, Raman spectroscopy and X-ray diffraction analysis. The Co₃O₄/graphene anode can deliver a capacity of more than 800 mA h g⁻¹ reversibly at a 200 mA g⁻¹ rate in the voltage range between 3.0 and 0.001 V. The high reversible capacity is retained at elevated current densities. At a current rate as high as 1000 mA g⁻¹, the Co₃O₄/graphene anode can deliver more than 550 mA h g ⁻¹, which is significantly higher than the capacity of current commercial graphite anodes. The superior electrochemical performance of the Co₃O₄/graphene is attributed to its unique nanostructure, which intimately combines the conductive graphene network with uniformly dispersed nano Co₃O₄ particles.     

Rice husk-derived SiOx@carbon nanocomposites as a high-performance bifunctional electrode for rechargeable batteries

This paper we use ZnCl₂ to activates and reduces rice husks to produce SiO_x@N-doped carbon core-shell nanocomposites with inner voids is a facile and effective strategy to improve the electrochemical performance. As an anode material for the lithium-ion batteries, the composites exhibit a high reversible capacity (1315 mAh g⁻¹ after 100 cycles at 100 mA g⁻¹) and long-term stability (584 mAh g⁻¹ after 500 cycles at 500 mA g⁻¹). Such outstanding cycling stability is attributed to the small size of the SiO_x particles with inner voids and the carbon layer coating can guarantee good structural integrity for long cycle stability. As a cathode material for Li–S batteries, the composite displays a high capacity and good stability (675 mAh g⁻¹ after 100 cycles at 0.1C). Its good performance and facile preparation will improve the utilization of rice husk waste.     

Electrochemical performance of SiOC anodes prepared by a different silicone

SiOC is one of the most promising anodes for lithium-ion batteries, which shows the good structural stability and high capacity comparing to commercial graphite anode. In this paper, different SiOC anodes (SiOC-217, SiOC-H44, and SiOC-MK) were prepared from polymer precursors with different side groups (phenyl, methyl-phenyl, methyl) to investigate the effects of free carbon on the electrochemical performance of SiOC anodes. The results of X-ray photoelectron spectroscopy presented that SiOC was composed by different SiO_xC_4−x units and free carbon phase. The initial discharge capacity of SiOC-217 was 742.67 mA h g⁻¹. After 100 cycles, the reversible capacity of SiOC-217 reached 450.65 mA h g⁻¹ at 0.2 C, indicating a capacity retention rate of 60.68%. After cycling at high current densities, SiOC-217 exhibited a high discharge capacity of 592.88 mA h g⁻¹ at 0.1 C. SiOC-217 exhibited excellent electrochemical performance due to the high content of free carbon phase. Furthermore, the high contents of SiO₂C₂ and SiO₃C units further enhanced the improvement of electrochemical performance.     

Ultrafine SnO2 nanoparticles as a high performance anode material for lithium ion battery

In this paper, the ultrafine tin oxides (SnO₂) nanoparticles are fabricated by a facile microwave hydrothermal method with the mean size of only 14 nm. Phase compositions and microstructures of the as-prepared nanoparticles have been investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). It was found that the ultrafine SnO₂ nanoparticles are obtained to be the pure rutile-structural phase with the good dispersibility. Galvanostatic cycling and cyclic voltammetry results indicate that the first discharge capacity of the ultrafine SnO₂ electrode is 1196.63  mAh g⁻¹, and the reversible capacity could retain 272.63 mAh g⁻¹ at 100 mA g⁻¹ after 50 cycles for lithium ion batteries (LIBs). The excellent electrochemical performance of the SnO₂ anode for LIBs is attributed to its ultrafine nanostructure for providing active sites during lithium insertion/extraction processes. Pulverization and agglomeration of the active materials are effectively reduced by the microwave hydrothermal method.     

NiFe-NiFe2O4/rGO composites: Controlled preparation and superior lithium storage properties

Binary transition-metal oxides with spinel structure have great potential as advanced anode materials for lithium-ion batteries (LIBs). Herein, NiFe-NiFe₂O₄/ reduced graphene oxide (rGO) composites are obtained via a facile cyanometallic framework precursor strategy to improve the lithium storage performance of NiFe₂O₄. In the composites, NiFe-NiFe₂O₄ nanoparticles with adjustable mass ratios of NiFe₂O₄ to NiFe alloy are homogeneously deposited on rGO sheets. As anode material for LIBs, the optimized NiFe-NiFe₂O₄/rGO composite displays remarkably enhanced lithium storage performance with an initial specific capacity as high as 1362 mAh g⁻¹ at 0.1 A g⁻¹ and a decent capacity retention of ca. 80% after 130 cycles. Besides, the composite delivers a reversible capacity of 550 mAh g⁻¹ at 1 A g⁻¹ after 300 cycles. During the charge–discharge cycles, the aggregation of the NiFe-NiFe₂O₄ nanoparticles and the structural collapse of the electrode can be well alleviated by rGO sheets. Moreover, the conductivity of the electrode can be significantly improved by the well-conductive NiFe alloy and rGO sheets. All these contribute to the improved lithium storage performance of NiFe-NiFe₂O₄/rGO composites.     

Unique porous yolk-shell structured Co3O4 anode for high performance lithium ion batteries

This paper introduces a unique porous yolk-shell structured Co₃O₄ microball, which is synthesized by spray pyrolysis from precursor solution with polyvinylpyrrolidone (PVP) additive. PVP acts as an organic template in the pyrolytic reaction facilitating the formation of yolk-shell structure. The electrochemical properties of porous yolk-shell Co₃O₄ microballs evaluated as anode materials for lithium ion batteries exhibit high initial columbic efficiency of 77.9% and high reversible capacity of 1025 mAh g⁻¹ with capacity retention of 98.8% after 150 cycles at 1 A g⁻¹. In contrast, the hollow microballs obtained without PVP addition show obvious capacity decay from 1033 to 748 mAh g⁻¹ after 150 cycles with the capacity retention of 72.3%. In addition, the microballs with porous yolk-shell structure exhibit better rate performance. The superior electrochemical performance is mainly attributed to the unique porous yolk-shell structure which provides large voids to buffer volume expansion and enlarge the contact area with the electrolyte, shortening the diffusion path of the lithium ions.     

Porous rod-shaped Co3O4 derived from Co-MOF-74 as high-performance anode materials for lithium ion batteries

Porous rod-shaped Co₃O₄ has been successfully synthesized by one-step thermal annealing of the as-prepared Co-MOF-74 precursor and tested as anode materials for lithium ion batteries. The porous rod-shaped Co₃O₄ is found to be very attractive for lithium-ion batteries. It demonstrates a reversible capacity of 683 mAh/g after 80 cycles at 100 mA/g and an excellent rate performance with high average discharge specific capacities of 1231, 1026, 733 and 502 mAh/g at 50, 100, 200 and 400 mA/g, respectively. The excellent electrochemical performance should be due to the porous structural and composition characteristics.     

Surface engineering Co–B nanoflakes on Mn0.33Co0.67CO3 microspheres as multifunctional bridges towards facilitating Li+ storing performance

In virtue of high capacity and low manufacturing expense, transition metal carbonates (TMCs) have recently arisen enormous research interests as the anode materials for rechargeable lithium ion batteries (LIBs). However, the low electrical conductivity and unstable cycle performance impeded their further development. In this work, Co-B compounds are surface-engineered for the first time onto the mixed single-phase Mn_0.33Co_0.67CO₃ microspheres to accelerate the reaction kinetics and suppress the volume fluctuation of the electrodes during Li⁺ insertion/extraction. Specifically, Co-B nanoflakes not only function as the robust mechanical bridges between Mn_0.33Co_0.67CO₃ primary nanoparticles, but also provide extra pathways for electron/charge transport, both of which facilitate the improvement of electrochemical behaviors. Morever, the synergetic effect between Mn_0.33Co_0.67CO₃ and Co-B nanoflakes allow a high flux of Li⁺ across the interface to provide signifcantly boosted Li⁺ diffusivity. Impressively, the Mn_0.33Co_0.67CO₃@Co-B electrode delivers a high reversible capacity of 806 mA h g⁻¹ over 500 cycles at a high rate of 1.0 A g⁻¹, demonstrating its superior cycling stability. Therefore, surface engineering of borides may be an effective and promising way to improve the electrochemical behaviors of conversion type anodes like TMCs.     

Electrospinning-derived ZnCo2O4@carbon nanofiber composite for high-performance lithium ion storage

The degradation of the cobalt-zinc oxide structure and its poor conductivity during the charge and discharge limit their further applications for lithium ion storage. Herein, ZnCo₂O₄@carbon nanofiber composite with nano-fibrous structure is obtained by electrospinning, annealing in argon and low-temperature oxidation to effectively overcome the above issue. The active sites of ZnCo₂O₄ are evenly dispersed inside the carbon nanofibers, which can effectively avoid its aggregation and improve electrical conductivity. Additionally, the stable nanofibrous structure can maintain structural stability. The composite exhibits superior lithium ion storage capacity when being served as anode electrode. The ZnCo₂O₄@carbon nanofiber electrode possesses a high capacity of 1071 mA h g⁻¹ at 0.1 A g⁻¹. Besides, the electrode shows an outstanding rate capability of 505 mA h g⁻¹ at 3 A g⁻¹ and maintain 714 mA h g⁻¹ after 250 cycles when current density is adjusted to 0.2 A g⁻¹ again. Additionally, the electrode has an outstanding long-cycle performance, which remains a capacity of 447.165 mA h g⁻¹ at 0.5 A g⁻¹ after 500 cycles and 421.477 mA h g⁻¹ at 1 A g⁻¹ after 518 cycles. This result demonstrates that ZnCo₂O₄@carbon nanofiber composite has potential application prospects in the fields of advanced energy storage.     

Hierarchical nanoarchitecture of vanadium disulfide decorated 3D porous carbon skeleton with improved electrochemical performance toward Li ion battery and supercapacitor

Vanadium disulfide (VS₂) is deemed to be a competitive active material in electrochemical energy storage field in both lithium-ion battery and supercapacitor owing to its unique chemical and physical property. Nevertheless, serious aggregation and structure damage in continuous charge-discharges would result in a decreased capacity, an inferior cycling stability and a poor rate capability, which severly limits the practical application of VS₂. In this current work, a hierarchical porous nanostructured composite composed of VS₂ nanoparticles confined in gelatin-derived nitrogen-doped carbon network (VS₂-NC) was successfully designed and synthesized via a simple freeze drying plus an annealing method. In this VS₂-NC composite, porous architecture is conductive to providing high active surface areas, facilitating the access of electrolyte into active materials and ion diffusion. The confinement of carbon matrix on VS₂ nanoparticles is beneficial to inhibition of the volume change, reinforcement of the structural stability and improvement of the overall electrical conductivity of composite. Benefitting from the advantages mentioned above, the as-prepared VS₂-NC electrode demonstrates outstanding electrochemical performances. Employed as an anode for lithium ion battery, VS₂-NC delivers a relatively high reversible capacity about ～1061 mA h g^?1 in 200-cycle test at 100 mA g^?1. When applied in supercapacitor, VS₂-NC electrode manifests a large pseudocapacitance of 407.3 F g^?1 at a current density of 10 A g^?1 and superior cycling stability.