Carbon-coated manganese dioxide nanoparticles and their enhanced electrochemical properties for zinc-ion battery applications

In this study, we report the cost-effective and simple synthesis of carbon-coated α-MnOnanoparticles(α-MnO@C) for use as cathodes of aqueous zinc-ion batteries(ZIBs) for the first time. α-MnO@C was prepared via a gel formation, using maleic acid(CHO) as the carbon source, followed by annealing at low temperature of 270 °C. A uniform carbon network among the α-MnOnanoparticles was observed by transmission electron microscopy. When tested in a zinc cell, the α-MnO@C exhibited a high initial discharge capacity of 272 m Ah/g under 66 m A/g current density compared to 213 m Ah/g, at the same current density, displayed by the pristine sample. Further, α-MnO@C demonstrated superior cycleability compared to the pristine samples. This study may pave the way for the utilizing carbon-coated MnOelectrodes for aqueous ZIB applications and thereby contribute to realizing high performance eco-friendly batteries.

Preparation and Application of Manganese Dioxide/Graphene Composite in Lithium Sulfur Batteries

Graphene/manganese dioxide composites and grapheme/manganese dioxide/sulfur(G/MnO2/S) composite cathode were prepared by hydrothermal method and by vapor permeation, respectively. Their structure, morphology and specific surface area were characterized by X-ray diffraction, electron microanalysis and nitrogen adsorption analysis. The composites show morphology of nanosheets, high specific surface area and even distribution of sulfur. The sulfur accounts for 75% in the G/MnO2/S composite by thermogravimetric analysis. The electrochemical performance of G/S and G/MnO2/S cathode were investigated. The G/MnO2/S composite cathodes show excellent rate performance and cycle stability. At a 0.2C current density, initial discharge specific capacity is 1 061 m A·h·g^-1 and maintains 698 m A·h·g^-1 after 100 cycles;At a 1C current density, maximum discharge capacity reaches 816 m A·h·g^-1 and average capacity decreasing rate is only 0.073%/cycle after running over 400 cycles. Electrochemical mechanism of the composites cathodes was analyzed. The sulfur adsorption of Mn O2 inhibited the loss of active material sulfur, so, the electrochemical performance of the complex was improved.

Recent Advances on Challenges and Strategies of Manganese Dioxide Cathodes for Aqueous Zinc-Ion Batteries

Aqueous zinc-ion batteries(AZIBs)are regarded as promising electrochemical energy storage devices owing to its low cost,intrinsic safety,abundant zinc reserves,and ideal specific capacity.Compared with other cathode materials,manganese dioxide with high voltage,environmental protection,and high theoretical specific capacity receives considerable attention.However,the problems of structural instability,manganese dissolution,and poor electrical conductivity make the exploration of high-performance manganese dioxide still a great challenge and impede its practical applications.Besides,zinc storage mechanisms involved are complex and somewhat controversial.To address these issues,tremendous efforts,such as surface engineering,heteroatoms doping,defect engineering,electrolyte modification,and some advanced characterization technologies,have been devoted to improving its electrochemical performance and illustrating zinc storage mechanism.In this review,we particularly focus on the classification of manganese dioxide based on crystal structures,zinc ions storage mechanisms,the existing challenges,and corresponding optimization strategies as well as structure-performance relationship.In the final section,the application perspectives of manganese oxide cathode materials in AZIBs are prospected.

Flexible Zinc-Manganese Dioxide Alkaline Batteries Based on Kelp Electrolytes

Flexible energy-storage devices play a critical role in the development of portable, flexible and wearable electronics. In addition, biological materials including plants or plant-based materials are known for their safety, biodegradability, biocompatibility, environmental benignancy, and low cost. With respect to these advances, a flexible alkaline zinc-manganese dioxide (Zn-MnO2) battery is fabricated with a kelp-based electrolyte in this study. To the best of our knowledge, pure kelp is utilized as a semi-solid electrolyte for flexible Zn-MnO2 alkaline batteries for the first time, with which the as-assembled battery exhibited a specific capacity of 60 mA·h and could discharge for 120 h. Furthermore, the as-assembled Zn-MnO2 battery can be bent into a ring-shape and power a light-emitting diode screen, showing promising potential for the practical application in the future flexible, portable and biodegradable electronic devices.

Manganese Dioxide with High Specific Surface Area for Alkaline Battery

The authors reported a facile method for the synthesis of manganese dioxide without any template and catalyst at a low-temperature. The prepared sample was characterized with X-ray diffraction（XRD）, scanning electron microscopy（SEM）, Brunauer-Emmett-Teller（BET） surface analysis, Fourier transform infrared（FTIR） spectrometry, cyclic voltammetry, alternative current（AC） impedance test and battery discharge test. It is found that the prepared sample belongs to α-MnO2 and has a microsphere morphology and a large BET surface area. The electrochemical characterization indicates that the prepared sample displays a larger electrochemical capacitance than the commercial electrolytic manganese dioxides（EMD） in Na2SO4 solution, and exhibits larger discharge capacity than EMD, especially at a high rate discharge condition when it is used as cathode of alkaline Zn/MnO2 battery.

Oxygen-deficient titanium dioxide supported cobalt nano-dots as efficient cathode material for lithium-sulfur batteries

Lithium sulfur(Li-S)batteries demonstrate great promise for efficient energy storage systems once the lithium polysulfide(LPS)shuttling and sluggish redox kinetics can be well addressed.Herein,we developed a sea urchin-structured oxygen-deficient titanium dioxide semiconductor anchored with cobalt nano-dots(Co@TiO2-x)as a high-performance multifunctional sulfur host material for Li-S batteries.The sea urchin-structured Co@TiO2-x offers strong structural stability and strengthened chemical interaction towards LPS.Meanwhile,the incorporation of Co nano-dots into TiO2 leads to increased oxygen vacancies,which augments the electrical conduction and benefits LPS conversion acceleration as well.As a result,the oxygen vacancy-rich Co@TiO2-x composite exhibits excellent conductivity,strong LPS confinement and promoted sulfur electrochemical kinetics,rendering enhanced LPS shuttling inhibition and rapid redox reaction.Attributed to these features,the Co@TiO2-x/S cathode exhibits a discharge capacity of 803 mAh g-1at 1 C and a good cyclic stability upon 500 cycles with a low capacity fading rate of 0.07%per cycle.This synergistic design of conductive multifunctional LPS barrier is also promising to enlighten the material engineering in other energy storage applications.

A Binder-Free Amorphous Manganese Dioxide for Aqueous Zinc-Ion Battery

Aqueous zinc-ion battery has attracted much attention due to its low price, high safety, and high theoretical specific capacity. However, most of their performances are limited by the unsatisfied architecture of cathodes. Herein, we fabricated amorphous manganese dioxide by an in situ deposition method. The amorphous manganese dioxide can directly serve as the cathode of an aqueous zinc-ion battery without a binder. The resultant cathode exhibits a high specific capacity of 133.9 mAh/g at 200 mA/g and a capacity retention of 82% over 50 cycles at 1 A/g.

Effects of current density on preparation of grainy electrolytic manganese dioxide

Grainy electrolytic manganese dioxide was prepared by electrodeposition in a 0.9 mol/L MnSO4 and 2.5 mol/LH2SO4 solution. The structure, particle size and appearance of the grainy electrolytic manganese dioxide were determined by powder X-ray diffraction, laser particle size analysis and scanning electron micrographs measurements. Current density has important effects on cell voltage, anodic current efficiency and particle size of the grainy electrolytic manganese dioxide, and the optimum current density is 30 A/dm2. The grainy electrolytic manganese dioxide electrodeposited under the optimum conditions consists of γ-MnO2 with an orthorhombic lattice structure; the grainy electrolytic manganese dioxide has a spherical or sphere-like appearance and a narrow particle size distribution with an average particle diameter of 7.237 μm.

Preparation and electrochemical properties of nanosized tin dioxide electrode material by sol-gel process

Nanosized SnO 2 powders were prepared by sol gel process using inorganic salt as a precursor. The tin oxide powders obtained at different calcinating temperatures (300700 ℃) were investigated by means of X ray diffraction(XRD), infrared spectrum (IR), thermogravimetric analysis (TGA), differential thermal analysis (DTA) and transmission electron microscopy (TEM) as well. The results indicate that well crystallized nanosized SnO 2 powders with a structure of rutile and uniform size about 10 nm can be obtained when the calcinating is carried out at 550 ℃ for 3 h using the method. The electrochemical properties of nanosized SnO 2 powders as anode material for lithium ion batteries were also studied in detail. The results show that nanosized SnO 2 is a candidate of anode material for lithium ion batteries with reversible capacity more than 372 mA·h/g after ten cycles and low voltage for Li + intercalation and de intercalation.

Effects of temperature and concentration of sulfuric acid on the electrodeposition of grainy electrolytic manganese dioxide

The effects of temperature and the concentration of sulfuric acid on the cell voltage, the anode current efficiency of electrodeposition and the particle size of grainy electrolytic manganese dioxide （EMD） were investigated. The structure, particle size and appearance of grainy EMD were determined by powder X-ray diffraction, laser particle size analysis and scanning electron micrograph measurements. As the concentration of sulfuric acid increases, both the cell voltage and the average anode current efficiency decrease. With the increase of electrolysis temperature in the range of 30-60℃, the cell voltage, average anode current efficiency and particle size decrease. The optimum temperature of 30℃ and concentration of sulfuric acid of 2.5 mol/L for electrodeposition of the grainy EMD were obtained. XRD patterns show that the grainy EMD electrodeposited under the optimum conditions consists of γ-MnO2 and has an orthorhombic lattice structure. According to the results of SEM, the grainy EMD has a spherical or sphere-like appearance and a narrow particle size distribution with an average size of about 7μm. The grainy EMD is a promising cathode of rechargeable alkaline batteries for high energy density and a prospective precursor for production of the LiMn2O4 cathode of lithium ion batteries.

Tuning the crystalline and electronic structure of ZrO_(2)via oxygen vacancies and nano-structuring for polysulfides conversion in lithium-sulfur batteries

The recent emergence of tetragonal phases zirconium dioxide(ZrO_(2))with vacancies has generated significant interest as a highly efficient and stable electrocatalyst with potential applications in trapping polysulfides and facilitating rapid conversion in lithium-sulfur batteries(LSBs).However,the reduction of ZrO_(2)is challenging,even under strong reducing atmospheres at high temperatures and pressures.Consequently,the limited presence of oxygen vacancies results in insufficient active sites and reaction interfaces,thereby hindering practical implementation.Herein,we successfully introduced abundant oxygen vacancies into ZrO_(2)at the nanoscale with the help of carbon nanotubes(CNTs-OH)through hydrogen-etching at lower temperatures and pressures.The introduced oxygen vacancies on ZrO_(2-x)/CNTs-OH can effectively rearrange charge distribution,enhance sulfiphilicity and increase active sites,contributing to high ionic and electronic transfer kinetics,strong binding energy and low redox barriers between polysulfides and ZrO_(2-x).These findings have been experimentally validated and supported by theory calculations.As a result,LSBs assembled with the ZrO_(2-x)/CNTs-OH modified separators demonstrate excellent rate performance,superior cycling stability,and ultra-high sulfur utilization.Especially,at high sulfur loading of 6 mg cm^(-2),the area capacity is still up to 6.3 mA h cm^(-2).This work provides valuable insights into the structural and functional optimization of electrocatalysts for batteries.

The Future Trend of E-Mobility in Terms of Battery Electric Vehicles and Their Impact on Climate Change: A Case Study Applied in Hungary

The transportation sector is responsible for 25% of the total Carbon dioxide (CO2) emissions, whereas 60.6% of this sector represents small and medium passenger cars. However, as noted by the European Union Long-term strategy, there are two ways to reduce the amount of CO2 emissions in the transportation sector. The first way is characterized by creating more efficient vehicles. In contrast, the second way is characterized by changing the fuel used. The current study addressed the second way, changing the fuel type. The study examined the potential of battery electric vehicles (BEVs) as an alternative fuel type to reduce CO2 emissions in Hungarys transportation sector. The study used secondary data retrieved from Statista and stata.com to analyze the future trends of BEVs in Hungary. The results showed that the percentage of BEVs in Hungary in 2022 was 0.4% compared to the total number of registered passenger cars, which is 3.8 million. The simple exponential smoothing (SES) time series forecast revealed that the number of BEVs is expected to reach 84,192 in 2030, indicating a percentage increase of 2.21% in the next eight years. The study suggests that increasing the number of BEVs is necessary to address the negative impact of CO2 emissions on society. The Hungarian Ministry of Innovation and Technologys strategy to reduce the cost of BEVs may increase the percentage of BEVs by 10%, resulting in a potential average reduction of 76,957,600 g/km of CO2 compared to gasoline, diesel, hybrid electric vehicles (HEVs), and plug-in hybrid vehicles (PHEVs).

Preparation of anatase TiO_2 with assistance of surfactant OP-10 and its electrochemical properties as an anode material for lithium ion batteries

With the assistance of nonionic surfactant （OP-10） and surface-selective surfactant （CH3COOH）, anatase TiO2 was prepared as an anode material for lithium ion batteries. The morphology, the crystal structure, and the electrochemical properties of the prepared anatase TiO2 were characterized by scanning electron microscopy （SEM）, X-ray diffraction （XRD）, electrochemical impedance spectroscopy （EIS）, and galvanostatic charge and discharge test. The result shows that the prepared anatase TiO2 has high discharge capacity and good cyclic stability. The maximum discharge capacity is 313 mAh.g^-1, and there is no significant capacity decay from the second cycle.

Synthesis of dandelion-like TiO_2 microspheres as anode materials for lithium ion batteries with enhanced rate capacity and cyclic performances

Dandelion-like TiO2 microspheres consisting of numerous rutile single-crystalline nanorods were synthesized for the first time by a hydrothermal method. Their crystal structure, morphology and electrochemical properties were characterized by X-ray diffraction （XRD）, scanning electron microscopy （SEM）, transmission electron microscopy （TEM）, and galvanostatic charge and discharge tests. The results show that the synthesized TiO2 microspheres exhibit good rate and cycle performances as anode materials of lithium ion batteries. It can be found that the dandelion-like structure provides a larger specific surface area and the single-crystalline nanorod provides a stable structure and fast pathways for electron and lithium ion transport, which contribute to the rate and cycle performances of the battery.

β-MnO_(2) with proton conversion mechanism in rechargeable zinc ion battery

Rechargeable aqueous zinc ion battery(RAZIB)is a promising energy storage system due to its high safety,and high capacity.Among them,manganese oxides with low cost and low toxicity have drawn much attention.However,the under-debate proton reaction mechanism and unsatisfactory electrochemical performance limit their applications.Nanorod b-MnO_(2) synthesized by hydrothermal method is used to investigate the reaction mechanism.As cathode materials for RAZIB,the Zn//b-MnO_(2) delivers 355 mA h g^(-1)(based on cathode mass)at0.1 A g^(-1),and retain 110 mA h g^(-1) after 1000 cycles at 0.2 A g^(-1).Different from conventional zinc ion insertion/extraction mechanism,the proton conversion and Mn ion dissolution/deposition mechanism of b-MnO_(2) is proposed by analyzing the evolution of phase,structure,morphology,and element of b-MnO_(2) electrode,the pH change of electrolyte and the determination of intermediate phase MnO OH.Zinc ion,as a kind of Lewis acid,also provides protons through the formation of ZHS in the proton reaction process.This study of reaction mechanism provides a new perspective for the development of Zn//MnO_(2) battery chemistry.

Core-shell structured 1,4-benzoquinone@TiO_2 cathode for lithium batteries

Organic carbonyl compounds are considered as promising candidates for lithium batteries due to theirhigh capacity and environmental friendliness, However, they suffer from serious dissolution in the elec-trolyte, leading to fast capacity decay. Here we report core-shell structured 1,4-benzoquinone@titaniumdioxide （BQ@TiO2） composite as cathode for lithium batteries. The composite cathode can deliver a highdischarge capacity of 441.2 mA h/g at 50 mA/g and a high capacity retention of 80.7% after 100 cycles. Thegood cycling performance of BQ@TiO2 composite can be attributed to the suppressed dissolution of BQ,which results from the physical confinement effect of Ti02 shell and the strong interactions between BQand Ti02. Moreover, the combination of ex situ infrared spectra and density functional theory calculationsreveals that the active redox sites of BQ are carbonyl groups. This work provides an alternative way tomitigate the dissolution of small carbonyl compounds and thus enhance their cycling stability.

Bronze TiO2 as a cathode host for lithium-sulfur batteries

Lithium-sulfur batteries(LSBs)are very promising for large-scale electrochemical energy storage.However,dissolution and shuttling of lithium polysulfides(LiPSs)intermediates have severely affected their overall electrochemical properties and limited their practical application.Designing polar cathode hosts that can effectively bind LiPSs and simultaneously promote their redox conversion is crucial for realizing high-performance LSBs.Herein,we report bronze TiO2(TiO2-B)nanosheets(~5 nm in thickness)chemically bonded with carbon as a novel multifunctional cathode host for advanced LSBs.Experimental observation and first-principles density functional theory(DFT)calculations reveal that the TiO2-B with exposed(100)plane and Ti^3+ions exhibited high chemical affinity toward polysulfides and effectively confined them at surface.Meantime,Ti^3+ions and interface coupling with carbon promoted electronic conductivity of the composite cathode,leading to enhanced redox conversion kinetics of LiPSs during charge/discharge.Consequently,the as-assembled TiO2-B/S cathode manifested high capacity(1165 mAh/g at 0.2 C),excellent rate capability(244 mAh/g at 5 C)and outstanding cyclability(572 mAh/g over 500cycles at 0.2 C).This work sheds insights on rational design and fabrication of novel functional electrode materials for beyond Li-ion batteries.

Carbon coated ultrasmall anatase TiO_2 nanocrystal anchored on N,S-RGO as high-performance anode for sodium ion batteries

Anatase TiO_2 has been investigated as one of the most promising anode materials for sodium ion batteries(SIBs)with low cost and high theoretical capacity.Herein,a composite material of TiO_2 /N,S-RGO@C with carbon coated ultrasmall anatase TiO_2 anchored on nitrogen and sulfur co-doped RGO matrix was successfully prepared by a rational designed process.The composite structure exhibited ultrasmall crystal size,rich porous structure,homogeneous heteroatoms doping and thin carbon coating,which synergistically resulted in elevated electron and ion transfer.The anode exhibited high rate capacities with good reversibility under high rate cycling.The carbon coating was investigated to be effective to prevent active material falling and lead to long term cycling performance with a high capacity retention of 181 m Ah g^(à1)after 2000cycles at 2 C.Kinetic studies were carried out and the results revealed that the superior performance of the composite material were derived from the decreased charge transfer resistance and elevated ion diffusion.Results suggested that the TiO_2 /N,S-RGO@C composite is a promising anode material for sodium ion batteries.

Studies on TiO2/Reduced Graphene Oxide Composites as Cathode Materials for Magnesium-Ion Battery

The aim of this work is to introduce a high performance cathode for magnesium-ion batteries. TiO2/reduced graphene oxide (rGO) composites were mixed in ball mill. The samples are charac- terized using XRD and SEM. The spex-milled composites exhibit better electrochemical perfor- mance with higher reversible capacity and excellent cyclability. The excellent electrochemical performance of TiO2/rGO composites is due to their unique structures, which intimately combine the conductive graphene nanosheets network with TiO2 nanoparticles and possess the characteristic parallel channels running along the [010] orientation, which allow easy Mg2+ transport. It was found that layered TiO2 and rGO nanosheets in the composite interlace with each other to form novel sandwich-structured microspheres, which exhibit preferable electrochemical performance in rechargeable Mg batteries.

Engineered nitrogen doping on VO_(2)(B)enables fast and reversible zinc-ion storage capability for aqueous zinc-ion batteries

Vanadium-based compounds with high theoretical capacities and relatively stable crystal structures are potential cathodes for aqueous zinc-ion batteries(AZIBs).Nevertheless,their low electronic conductivity and sluggish zinc-ion diffusion kinetics in the crystal lattice are greatly obstructing their practical application.Herein,a general and simple nitrogen doping strategy is proposed to construct nitrogen-doped VO_(2)(B)nanobelts(denoted as VO_(2)-N)by the ammonia heat treatment.Compared with pure VO_(2)(B),VO_(2)-N shows an expanded lattice,reduced grain size,and disordered structure,which facilitates ion transport,provides additional ion storage sites,and improves structural durability,thus presenting much-enhanced zinc-ion storage performance.Density functional theory calculations demonstrate that nitrogen doping in VO_(2)(B)improves its electronic properties and reduces the zinc-ion diffusion barrier.The optimal VO_(2)-N400 electrode exhibits a high specific capacity of 373.7 mA h g^(-1)after 100 cycles at 0.1 A g^(-1)and stable cycling performance after 2000 cycles at 5 A g^(-1).The zinc-ion storage mechanism of VO_(2)-N is identified as a typical intercalation/de-intercalation process.