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Growing temperatures and planting dates affect phenology and grain yields of maize varieties and farmers have to choose suitable varieties that fit into different planting dates and growing temperatures. A field experiment was conducted to investigate the response of different hybrid maize varieties to different growing temperatures through growing the varieties at different locations varying in altitudes (low land, mid altitude and highlands) under three planting dates. Results revealed that days to seed emergence were influenced by growing temperatures, with days to emergence difference of two weeks observed between Didesa/Uke (high temperature locations) and Holeta (low temperature location). Almost for all varieties except for BH546, days to tasseling and maturity were longer under low temperature at Holeta while they were shorter under high temperature at Didesa and Uke. Early planting resulted in higher grain yields especially at Uke, Bako and Ambo. Grain yield was influenced by the interaction effect of variety and temperature, with BH546 being more yielder than AMH851 under high temperature at Uke. Thus, for most of the tested varieties early planting is recommended, as this will enable the varieties to escape moisture stress that occasionally occurs at grain filling and maturation period, which can seriously affect grain yield. Key words: Growing temperature, grain yield, maize phenology, maize varieties, planting date.

Ab-initio, anatase titanium dioxide (TiO2) nanotubes were prepared from pristine anatase titanium dioxide (TiO2) nanoparticles via a low temperature modified stirring-hydrothermal technique. Scanning electron microscope (SEM) characterization of the as-synthesized sample depicted uniformly distributed one-dimensional nanotubular morphology, with an average length, thickness and diameter of ∼ 4 μ m , 17 nm and 20 nm, respectively. N 2 physisorption of the sample revealed two distinct peaks at mesopore and macropore scales of 3 nm and 100 nm, respectively. The specific surface area of the materials was observed to have increased from 8 m2 g−1 for the pristine to 62 m2 g−1 for the nanotubes. X-ray diffraction analysis indicated a tetragonal symmetry for the anatase TiO 2 nanotubes sample, which is similar to those reported in the literature. Core levels and elemental analyses showed the presence of titanium and oxygen in good proportion. Electrochemical performances of the TiO 2 nanotubes electrode offered good cyclic stability, good rate capability and a fairly large capacity of 160 mA h g−1 at a specific current of 36 mA g−1.

Tin oxide, SnO2, is a suitable anode for both lithium-ion and sodium-ion batteries (LIBs and SIBs) unlike graphite and silicon, which are only suitable anodes for LIB. SnO2 has garnered much attention because of its high theoretical capacities (LIB = 1494 mA h g−1 and SIB = 1378 mA h g−1). However, the commercialization of SnO2 anodes is still hugely challenged because these anodes suffer from large volume expansion caused by lithiation/delithiation or sodiation/desodiation during cycling, leading to severe capacity fading. The adopted strategies to solve these problems are nanosizing that greatly improves the structural stability of the material and helps to have fast reaction kinetics. Synthesizing nanocomposite of SnO2 nanoparticles with nanoporous carbonaceous materials to buffer the volume expansion, enhance cycling stability; create oxygen deficiency to improve intrinsic conductivity. In this review, the recent research trends on SnO2 as anode for both LIB and SIB systems are presented.

In recent years, interest in nanostructured electrode materials for use in supercapacitors has been on the rise. Nickel oxide has been reported as a good candidate for supercapacitor applications due to its high theoretical capacitance and low cost. However, its poor electrical conductivity has resulted in actual poor specific capacitance and cycling ability. Over the years, researchers have studied various techniques to modify the structure and composition of NiO with the aim of improving its electrochemical performance. In this review, we opine that NiO-based electrodes can be fabricated using different approaches and different composite forms in order to obtain cells of high efficiency and specific capacitances. We discuss the recent advances in NiO-based electrodes fabricated using different approaches.

With a low cost and high volumetric capacity, rechargeable magnesium batteries (RMBs) have been emerged as promising candidates for post-lithium ion batteries. The kinetically sluggish Mg2+ inserti...

There is a huge maize yield gap in Ethiopia. The use of improper maize agronomic practices could contribute to maize yield gaps. Agronomic panel survey (APS) and a baseline survey were carried out by EIAR and CSA, respectively in collaboration with CIMMYT for three years (2015-17) to assess the rates and types of inorganic fertilizers applied; maize varieties used and plant densities maintained by farmers in major maize growing areas of Ethiopia. The APS were conducted by EIAR in 3 to 4 grids of 10 km × 10 km size in five zones while the baseline survey was conducted by CSA in nine zones following their own protocol. Results showed that most of the surveyed farmers (95%) grow improved hybrid maize varieties and >85% of them grow the improved varieties within the agro-ecology they were recommended for. Maize variety BH661 was the commonest maize variety in Jimma zone, BH660 in West Gojam and West Shoa zones, Limu in West Shoa and East Wollega zones and BH540 in East Shoa zone. Most of the surveyed farmers (89.5%) apply fertilizer for maize production out of which 75% of them apply inorganic fertilizers, 20.5% only organic and 4.5% both types. In most maize growing areas, farmers apply fertilizer rates very close to the blanket recommended rate of 100 kg NPS and 200 kg UREA. However, a consistently higher inorganic fertilizer rate was applied in West Gojam and the lowest in East Shoa Zones. The plant density at harvest was lower than any of the recommended plant densities for most of the maize growing zones. As an average of all zones and years, about 87.5% farmers maintained plant density at harvest below the recommended. Mean grain yield was above the national average for most of the study areas, but exceptionally higher for Gojam and Wollega zones and lower for East Shoa zone. There was a positive relationship between cob number and plant density, plant density and grain yield, cob number and grain yield, implying using sub-optimal plant density could potentially affect grain yield. Key words: Fertilizer rate, grain yield, maize varieties, plant density, Zea mays.

Variability in crop response and nutrient use efficiencies to fertilizer application is quite common under varying soil and climatic conditions. Understanding such variability is vital to develop farm- and area- specific soil nutrient management and fertilizer recommendations. Hence the objectives of this study were to assess maize grain yield response to nutrient applications for identifying yield-limiting nutrients and to understand the magnitude of nutrient use efficiencies under varying soil and rainfall conditions. A total of 150 on-farm nutrient omission trials (NOTs) were conducted on farmers’ field in high rainfall and moisture stress areas. The treatments were control, PK, NK, NP, NPK and NPK+ secondary and micronutrients. Maize grain yield, nutrient uptake, agronomic and recovery efficiencies of N and P differed between fertilizer treatments and between the contrasting agro-ecologies. The AEN ranged from 24.8 to 32.5 kg grain kg-1 N in Jimma area and from 1.0 kg grain kg-1 N (NK treatment) to 10.2 kg grain kg-1 N (NPK treatment) at Adami Tullu and from 0.1 kg grain kg-1 N (NK treatment) to 8.3 kg grain kg-1 N (NPK treatment) at Bulbula. The differing parameters between the agro-ecologies were related to difference in rainfall amount and not to soil factors. Grain yield response to N application and agronomic efficiencies of N and P were higher in the high rainfall area than in the moisture stress areas. Grain yield responded the most to nitrogen (N) application than to any other nutrients at most of the experimental sites. Owing to the magnificent yield response to N fertilizer in the current study, proper management of nitrogen is very essential for intensification of maize productivity in most maize growing areas of Ethiopia.

Onion-like carbon (OLC) integrated α-MnO2 nanorods (α-MnO2/OLC) composite has been studied as a viable cathode material for potential development of high-performance zinc-ion batteries (ZIBs). XRD results revealed the tetragonal phase of the α-MnO2 materials, and the FE-SEM and HR-TEM images show nano-sized rod-shaped morphology with an average diameter of 30 nm. The BET surface area of the α-MnO2/OLC composite was almost 6 times (247.22 m2/g) higher than that of the pristine (42.48 m2/g) material and the thermogravimetric investigation was exposed 50% of MnO2 and 50% OLC is presented in the composite. The electrochemical performance of the cells was evaluated by galvanostatic cycling (GC), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) using 1 M ZnSO4 plus 0.1 M MnSO4 additive as electrolyte and Zn foil as the anode. Cycling results indicate that α-MnO2/OLC composite exhibits a stable and high reversible capacity of 168 mAh g−1 (93% capacity retention) compared to the α-MnO2 material with a capacity of 104 mAh g−1 (81% capacity retention) after 100 cycles.

The South African Research Chairs Initiative of the Department of Science and Technology, South Africa and National Research Foundation of South Africa (Grant No. 61056). K. O. appreciates the financial assistance from the University of Pretoria, South Africa and National Research Foundation (NRF) of South Africa for studentship grants.

In this paper, the bending analysis of Multi-wall carbon nanotubes (MWCNT) reinforced honeycomb core sandwich composite plate has been performed based on the higher-order shear deformation theory using finite element formulations. The parametric study on the static behavior of honeycomb sandwich composite plates hybrid with MWCNT with the influence of the weight percentage of CNTs for core material and upper and bottom skins with various boundary conditions, different ply configuration was performed. The numerical study clearly shows that the bending deflection decrease with an increase in the weight percentage of MWCNTs. The boundary condition C-C-C-C has the lowest deflection while the C-F-F-F end condition has the highest deflection irrespective of ply configuration considered. The deflection of the sandwich plate with MWCNT can be found almost two times lower than deflection without MWCNT due to higher stiffness offered by fillers. It can be observed that the influence of MWCNT in the core is least contributing to increasing the stiffness with the influence of MWCNT in the skins on the bending characteristics. Finally, It can be concluded that this study reveals the influence of adding fillers in the core and skins has much difference in the bending characteristics of MWCNT reinforced honeycomb core sandwich composite plate.

Copyright: 2019, Taylor & Francis Group, CRC Press. Due to copyright restrictions, the attached PDF file contains the abstract of the full-text item. For access to the full-text item, please consult the publisher's website: https://www.taylorfrancis.com/books/e/9780367855116

The lithium ion battery has been offering a tremendous benefit and contribution to the technological development of humankind by serving as an efficient power source for electronic devices, mobile power stations, and electrical automotive vehicles since its introduction. The three major components of a lithium ion battery: the cathode, anode, and electrolyte have a crucial role in the electrochemical performance of the battery. The layered LiMO2 (M = Co, Mn, Ni), spinel LiMn2O4, olivine LiFePO4, and silicates Li2MSiO4 (M = Fe, Mn) structures are the famous categories of cathodes of lithium ion batteries. These categories of cathode materials have their own advantages, as well as associated intrinsic challenges in terms of capacity retention and rate capabilities. Recently, many efforts were employed to understand the fundamental electrochemistry, and they used various strategies to solve the challenges of these cathode materials and enhance their electrochemical performances. In this chapter, we discussed in detail the fundamental electrochemical mechanism of the cathode part (the positive electrode) of the lithium ion battery and summarised the relevant research findings related to the cathode materials.

Copyright: 2019, Taylor & Francis Group, CRC Press. Due to copyright restrictions, the attached PDF file contains the abstract of the full-text item. For access to the full-text item, please consult the publisher's website: https://www.taylorfrancis.com/books/e/9780367855116

Copyright: 2019, Taylor & Francis Group, CRC Press. Due to copyright restrictions, the attached PDF file contains the abstract of the full-text item. For access to the full-text item, please consult the publisher's website: https://www.taylorfrancis.com/books/e/9780367855116

Due to copyright restrictions, the attached pdf does not contain the fulltext version of the published book. For access to the fulltext version, kindly access the publisher's website at https://www.crcpress.com/Electrochemical-Devices-for-Energy-Storage-Applications/Kebede-Ezema/p/book/9780367425678

Copyright: 2019, Taylor & Francis Group, CRC Press. Due to copyright restrictions, the attached PDF file contains the abstract of the full-text item. For access to the full-text item, please consult the publisher's website: https://www.taylorfrancis.com/books/e/9780367855116

Smart city deals with the problems of rapid urbanization and population growth by optimal utilization of all available resources. There are other driving factors such as clean energy programmes, a low carbon economy and distributed energy resources that are included in a smart city concept. Therefore, in this article, the authors proposed a clean energy generating model by utilizing the kinetic energy of vehicles over a speed breaker. The article focused on the design, modelling, and simulation of an electromechanical system for generating electrical power from the kinetic energy of vehicles passing over speed breakers. To facilitate simulation, a model of the electromechanical system is developed in MATLAB/Simulink. Further, MULTISIM 14 software is utilized for power electronic device modelling and simulation. Simulation results for power generation are obtained considering four units of rotational induction generators and two units of translational induction generators.

LiMn2O4 (LMO) powders were prepared by modified chemical bath deposition (CBD) method by varying ammonium hydroxide solution (AHS). The volume of the AHS was varied from 5 to 120 mL in order to determine the optimum volume that is needed for preparation of LMO powders. The effect of AHS volume on the structure, morphology, and electrochemical properties of LMO powders was investigated. The X-ray diffraction (XRD) patterns of the LMO powders correspond to the cubic spinel LMO phase. It was found that the XRD peaks increased in intensity with increasing volume of the AHS up to 20 mL. The estimated average grain sizes calculated using the XRD patterns were found to be in the order of 66 ± 1 nm. It was observed that the estimated average grain sizes increased up to 20 mL of AHS. The scanning electron microscopy (SEM) results revealed that the AHS volume does not influence the surface morphology of the prepared nano-powders. Elemental energy dispersive (EDS) analysis mapping conducted on the samples revealed homogeneous distribution of Mn and O for the sample synthesized with 120 mL of AHS. The UV–Vis spectra showed a red shift with an increase in AHS up 20 mL. The cyclic voltammetry and galvanostatic charge/discharge cycle testing confirmed that 20 mL of AHS has superior lithium ion kinetics and electrochemical performance.

A V2O5 anode material significantly challenged on its further development to be used in lithium ion batteries in-terms of its structural degradation, poor cyclability and low conductivity. Thus researchers started to work on composite matrix such as V2O5–P2O5 and in this work we synthesized pristine and 7.5% GNP modified 75V2O5–25P2O5 and used for the first time as anode for lithium-ion batteries; the anodes delivered with corresponding first discharge capacities of ∼1400 and ∼1600 mA h g−1 (almost equal to theoretical capacity of V2O5 1472 mA h g−1 during a fully reduction from V5+ to V0), respectively. The rapid capacity fade was observed in the first few initial cycles (up to 10th cycle) for both materials; however highest discharge capacity of 446 mAh g−1 was retained after 100th cycles for 7.5% GNP modified 75V2O5–25P2O5 than unmodified composite, with the capacity retention of 89% with respect to 10th cycle discharge capacity. The electrical conductivity of 75V2O5–25P2O5 drastically increases with GNP modification. The superior electrochemical performance of 75V2O5–25P2O5–7.5%GNP attributed to the high electronic and ionic conductivity of graphene nano-platelets.

A facile chemical solution deposition via two-step spin coating technique was used to fabricate nano-particulate novel Sn doped Co3O4 thin film for glucose sensor and fuel cell applications. Substitution of Sn into Co3O4 host lattice lead to a remarkable increase in the electrocatalytic activity of the Co3O4 electrode material. Film thickness played a significant role in enhancing the charge transferability of the electrode as was observed from electrochemical impedance spectroscopy (EIS). The best sensor exhibited two wide linear response ranges (2μM up to ∼ 0.5 mM and 0.6 mM up to ∼5.5 mM respectively) with sensitivities of 921 and 265 μAcm−2mM−1 respectively and low limit of detection of 100 nM (S/N=3). The sensor was very selective towards glucose in the presence of various interference and showed long term stability. Moreover, the developed thin film modified electrode could generate one electron current in nonenzymatic fuel cell setup at room temperature.

The soils of Jinka in Southern Ethiopia were studied based on the detail works on soil pit description, characterizing and classification following the FAO and USDA guidelines. For this, along with the topo-sequence and landscape, six soil profiles were opened on an area of 100 ha of research field to make them suit for sustainable soil management practices. The soils were generally described as dark reddish brown to very dark brown and deep. These soils were characterized as slightly (4.87) to moderately acidic (6.18). The OC and available phosphorus were found to range from low to medium. All micronutrients were found to be highly associated with lower soil reaction. These soils group can be classified as Cambisols. Therefore, amending the soil with lime based on exchangeable acidity, essential and deficient nutrients will be vital for supplying food and feed crops in the region. However, continuous assessment of the nutrient status at every five to seven years is necessary to make sure that the soil quality is maintained. Key words: Blocky, consistency, friable, granular, sub-angular, structure.

Copyright: The Author(s) 2017. This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 License which permits unrestricted reuse of the work in any medium, provided the original work is properly cited.

Nowadays, construction industry is becoming one of the fastest growing economic sub sectors in Ethiopia. Minimizing the expected contractual risk is the right strategy to develop the industry. To this end, in construction contracts presenting bank demand guarantee by the contractor is a common trend in our country and in other countries of the world. This demand guarantee/Unconditional bond is chosen due to its being payable by the bank immediately and unconditionally where the beneficiary demands the payment in an alleged nonperformance of the contract by the side of the contractor. Thus, due to its being fast source of money where this problem happens, demand guarantee is said to be “as good as cash in hand.” Accordingly, the nature and purpose of this instrument is supplemented by the “principle of autonomy” which states that, the rights and obligations created by the guarantee are independent from the main construction contract. As a result, the idea of the stated principle presupposes that the operation of demand guarantee will not be interfered with by courts in injunction order to stop its payment to the beneficiary on grounds immaterial with the guarantee. On the other hand, there are exceptional circumstances acknowledged by different jurisdictions which opens a room to court involvement, the two most of these are; where there is “Fraud”, and “Illegality”, in the demand guarantee, and/or on underlying contract. So, the aim of this research is to examine for the practice of Ethiopian Federal Courts regarding court involvement in the operation of demand guarantee instrument, and the existence of a legal basis. To this end, court cases and the available legislations are analyzed in comparing other countries practice in case laws and legislations. In course of this, the findings reveal that in Ethiopia, there is no an adequate legal framework which covers all aspects of demand guarantees issue, and court involvement is unlimited and even unreasonable. And also there is legal interpretation gap in differentiating the nature and purpose of unconditional and conditional bonds in court cases. Finally, the research findings show that court interference in demand guarantee payment cases is unlimited that, the study recommends the promulgation of new specific law governing this area, the inclusion of the fraud and illegality exception in the new law and training to relevant stakeholders as possible solutions for the problem.

A simple solution based deposition process has been used to fabricate Zn doped Co3O4 electrode as an electrocatalyst for non-enzymatic oxidation of glucose. XRD, HRTEM, SEM, EELS, AFM, EIS was used to characterise the electrode. The addition of Zn as dopant on Co3O4 resulted in enhanced electrochemical performance of Zn:Co3O4 material compared to pristine Co3O4 due to increased charge transferability. The as prepared electrode showed fast response (

A nickel substituted spinel cathode material (LiMn1.9Ni0.1O4) with enhanced electrochemical performance was successfully synthesized by using a locally-sourced, low-cost manganese precursor, electrolytic manganese dioxide (EMD), and NiSO4·6H2O as a nickel source by means of a low temperature aqueous reduction synthesis technique. This synthesis protocol is convenient to scale up the production of the spinel cathode material, with minimal nickel content (Ni = 0.1) in the structure, for lithium-ion battery applications. Ni-ions substituting Mn-ions was confirmed using XRD, EDS, XPS and electrochemical performance studies. LiMn1.9Ni0.1O4 materials showed an octahedral shape with clearly exposed (111) facets that enhanced the Li-ion kinetics and improved the cycling performance compared to the pristine spinel sample (LiMn2O4). The LiMn1.9Ni0.1O4 sample exhibited superior capacity retention by retaining 84% of its initial capacity (128 mA h g−1) whereas pristine LiMn2O4 retained only 52% of its initial capacity (137 mA h g−1). XPS confirmed that the Mn3+/Mn4+ ratio changed with nickel substitution and favored the suppression of capacity fading. The study clearly suggests that the integration of small amounts of Ni into the spinel structure is able to eliminate the disadvantageous Jahn–Teller effects in the LiMn2O4.

High-performing LiAl x Mn2−x O4 (x = 0, 0.125, 0.25, 0.375, and 0.5) spinel cathode materials for lithium-ion battery were developed using a solution combustion method. The as-synthesized cathode materials have spinel cubic structure of LiMn2O4 without any impurity peak and accompanied with peak shift as doping with aluminium. LiAl0.375Mn1.625O4 (first cycle capacity = 113.1 mAh g−1) retains 85 % (96.2 mAh g−1), while pristine LiMn2O4 electrode (first cycle capacity = 135.8 mAh g−1) fades quickly and retains only 54 % (73.9 mAh g−1) after 50 cycles. The electrochemical performance of all the cathode samples prepared using the SCM is comparable to those reported for Al-doped LiMn2O4 spinel cathode materials. The experimental lattice parameter of LiAl x Mn2−x O4 was validated by ab initio calculations and correlated with the first cycle capacity of materials. The variation in lattice parameter as a result of Al doping greatly enhanced the cyclability of discharge capacity of the LiMn2O4 spinel.

Microwave irradiation at the pre- and post-annealing steps of the synthesis of LiAlxMn2−xO4 (x = 0 and 0.3) spinel cathode materials for rechargeable lithium ion batteries is a useful strategy to optimize the average manganese valence number (nMn) for enhanced capacity and capacity retention. The strategy impacts on the lattice parameter, average manganese valence, particle size and morphology, reversibility of the de-intercalation/intercalation processes, and capacity retention upon continuous cycling. Microwave irradiation is able to shrink the particles for improved crystallinity. The XPS data clearly suggest that microwave irradiation can be used to tune the manganese valence (nMn), and that the LiAlxMn2−xO4 with nMn ≈ 3.5+ gives the best electrochemical performance. These new findings promise to revolutionize how we use microwave irradiation in the preparation of energy materials and various other materials for energy storage and conversion materials for enhanced performance.

The scarcity of rapid and large scale synthesis of functional materials hinders the progress from the laboratory scale to commercial applications. In this study, we report a rapid and large scale synthesis of micron size (1.3 μm) Co3O4 octahedron particles enclosed by (111) facets. The octahedron particles were composed of ±25 nm rectangular/cube shaped particles as seen from the TEM images. We have characterized and evaluated the catalytic, supercapacitance and magnetic properties of the as prepared material. The Co3O4 octahedron particles were highly active in heterogeneous PMS activation reaction. Formation of Co–OH bonding due to water molecule dissociation on the (111) surface of the particles was evident from the ELNEFS analysis. The as prepared octahedron materials showed >4 times higher pseudocapacitance properties (182 F g−1) with good capacity retention ability (up to the 1000 cycles studied) compared to commercial microcrystalline Co3O4 powder (43 F g−1). The material showed interesting magnetic properties at low temperature. The coexistence of superparamagnetic single domain and linear/quadratic behaviours was observed at low temperature for the as prepared Co3O4 octahedron particles.

Spherically shaped Ni-substituted LiNixMn2-xO4 (x = 0, 0.1, 0.2) spinel cathode materials for lithium ion battery with high first cycle discharge capacity and remarkable cycling performance were synthesized using the solution-combustion technique. XRD confirmed the successful synthesis of the various spinel structures, with the Bragg diffraction peaks shifting to higher 2θ angles accompanied with lattice shrinking as the Ni concentration increased. The SEM images of the spinels revealed essentially spherical morphology. Galvanostatic charge-discharge experiments showed that by substituting the pristine spinel with a low amount of nickel enhanced the cell potential (hence the energy storage capability) and greatly improved the capacity retention (ca. 99%) even after 100 cycles. Electrochemical impedance spectroscopy experiments corroborated the enhanced capacity retention as lithium ion intercalation/de-intercalation resistance for the Ni substituted spinels was significantly improved (more than a magnitude higher) compared to the pristine spinel.

Pristine and Al-doped lithium manganese oxide (LiAl x Mn 2− x O 4 ) spinel cathode materials were successfully synthesized by combustion method using urea as reducer and fuel. The structural and electrochemical properties of the as-synthesized powders were characterized using scanning electron microscopy, X-ray diffraction, energy dispersive spectroscopy and charge/discharge testing. The effect of aluminium doping on the discharge capacity was studied for different aluminium concentration x = 0, 0.05, 0.1 and 0.5. The as-synthesized Al doped samples LiAl 0.05 Mn 1.95 O 4 and LiAl 0.1 Mn 1.9 O 4 exhibited higher discharge capacity for the first two cycles compared to the first cycle discharge capacity of pristine LiMn 2 O 4 . The first-principles calculations predict an increase in lattice parameter for x = 0.05 and 0.1 to be responsible for the increase in first cycle discharge capacity for x = 0.05 and 0.1. In addition, we have found that LiAl 0.5 Mn 1.5 O 4 sample exhibited the more stable capacity than the other samples.

A comparative study was carried out with the effect of nickel precursors on the electrochemical performance of spinel LiMn2−x Ni x O4 (x = 0, 0.1 and 0.2) cathode materials. The spinel materials were prepared by employing a low temperature aqueous reduction synthesis route using locally sourced low-cost manganese precursor electrolytic manganese dioxide (EMD), and Ni(NO3)26H2O as a nickel source. The EDS result has confirmed that the use of nickel nitrate provides more nickel content in the synthesized samples as compared to using nickel sulphate as a nickel source. Importantly, LiMn1.9Ni0.1O4 prepared with the nitrate salt showed the low impedance value (~294.7 Ω) than that of the nickel sulphate used spinel (~431.8 Ω), inferring that the nitrate salt generates low resistance in the spinel. The improved conductivity was observed with the small amount of nickel in both precursor used spinel, nickel salt used spinel showed high electrical conductivity (225.4 Ω) than the sulphate salt (330.7 Ω). A small amount of nickel addition showed the significant enhancement in capacity retention of LiMn1.9Ni0.1O4 and LiMn1.8Ni0.2O4 by retaining 88% and 145% of its initial capacity for nickel salt used spinel and the sulphate salt used spinel showed 83% and 92% of its initial capacity, respectively whereas the pristine LiMn2O4 showed only 56% of its initial capacity. The investigation clearly indicates that the substitution of small amounts of nickel into the spinel, irrespective of the precursor used effectively reduces the Jahn-Teller effects in the LiMn2O4.

A high-energy aqueous asymmetric electrochemical capacitor was developed using manganese dioxide (α-MnO2)/graphene oxide (GO) nanocomposites. The nanostructured α-MnO2 was prepared from micron-sized commercial electrolytic manganese dioxide (EMD) via a hydrothermal reaction in the presence and absence of sodium dodecylsulphate (SDS), α-MnO2(SDS) and α-MnO2, respectively. Unlike the as-prepared α-MnO2, the presence of SDS during the hydrothermal reaction conferred different morphologies on the intermediate precursors for the α-MnO2(SDS). Also, the XRD patterns showed that the α-MnO2(SDS) are more crystalline than the as-prepared α-MnO2. The superior electrochemical performance of the α-MnO2(SDS)/GO composite (280 F g−1, 35 Wh kg−1, and 7.5 kW kg−1 at 0.5 A g−1) coupled with excellent long cycle life clearly indicates that this electrode system has the potential of being developed as an efficient aqueous asymmetric electrochemical capacitor. The high performance of the α-MnO2(SDS)/GO composite was interpreted in terms of the enhanced crystallinity of the α-MnO2(SDS). Interestingly, the electrochemical performance is comparable to or even better than those reported for the more conductive graphene/MnO2 composites.

Long afterglow alkaline earth aluminates MAl 2 O 4 :Eu, Dy (M: Ca, Sr, Ba) phosphors are generally synthesized by the solid-state process which is more feasible than other conventional processes in terms of operation and large-scale production. However, the constituents of phosphors synthesized using this process are usually not mixed well, the particles agglomerates and very high temperature requirement to synthesize the final powder make it undesirable. In order to circumvent these problems, MAl 2 O 4 :Eu, Dy (Ca, Ba, Sr) phosphors were prepared at low temperatures (500 °C) by the solution–combustion of corresponding metal nitrate–urea solution mixtures, over a time of 5–10 min. In order to elucidate the relationship between the constituent, structure and PL properties product’s particle size, morphological and structural properties were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive X-ray spectrometer (EDS), while the characteristic luminescence properties were investigated using emission spectra. The low temperature monoclinic structure for both CaAl 2 O 4 and SrAl 2 O 4 and the hexagonal structure of BaAl 2 O 4 were observed. The emission spectra of these phosphors indicated that all of them are broad band, and the only emission peaks around 448, 490 and 515 nm of CaAl 2 O 4 :Eu, Dy, BaAl 2 O 4 :Eu, Dy and SrAl 2 O 4 :Eu, Dy, respectively, are due to 5d → 4f transition of Eu 2+ . The decay curves implied that these phosphors contain fast, medium and slow-decay process. The Dy 3+ trap levels may be considered to be responsible for the long afterglow phosphorescence at room temperature.

Spherical pristine LiMn2O4 and Ni doped LiNixMn2-xO4 (x=0.1, 0.2, 0.3, 0.4, 0.5) cathode materials for lithium ion battery with high first cycle discharge capacity and excellent cycle performance were synthesized using the solution-combustion technique. XRD analysis revealed peak shift towards higher angle and lattice shrink as a result of Ni doping. CSAFM result confirms LiNi0.5Mn1.5O4 provides higher current of 10nA than pristine LiMn2O4 of 0.05nA. The EIS result displays that small Ni content (x=0.1, 0.2) doping reduced the impedances of pristine LiMn2O4. The composition LiNi0.1Mn1.9O4 exhibits higher capacity and better cycleability than other Ni content compositions. Charge/discharge cycling result shows that Ni substitution substantially improved the capacity retention of LiMn2O4. All Ni doped LiNixMn2-xO4 (x= 0.1, 0.2, 0.3, 0.4, 0.5) compositions are able to retain 99% of their respective first cycle discharge capacities, whereas LiMn2O4 retains only 60% of its first cycle discharge capacity of 122 mAh/g after 50 cycles.

An aqueous asymmetric electrochemical capacitor was developed using manganese dioxide / multiwalled carbon nanotubes (MnO2/MWMWCNT) nanocomposites. The nanostructured MnO2 was generated from micron-sized commercial electrolytic manganese dioxide (EMD) via a hydrothermal reaction, with the addition of the surfactant sodium dodecylsulphate (SDS), and acid treatment. The capacitance of the nano-sized MnO2 was improved. The MnO2/MWCNT hybrid exhibited excellent specific capacitance (170 F g-1), energy density (18 Wh kg-1), power density (4 kW kg-1), satisfactory cycle life, and short response time.

Metal oxides such as TiO2, Li4Ti5O12, SnO2, SnO, M2SnO4 (\( \mathrm{M} = \mathrm{Z}\mathrm{n} \), Co, Mn, Mg), TMO (\( \mathrm{T}\mathrm{M} = \mathrm{M}\mathrm{n} \), Fe, Co, Ni, or Cu), TM3O4 (\( \mathrm{T}\mathrm{M} = \mathrm{C}\mathrm{o} \), Fe, or Mn), and lithium alloys Li–Sn, Li–Si are among the next-generation anode materials for lithium–ion batteries with high prospect of replacing graphite. Most of these anode materials have higher specific capacities between the range of \( 600 - 1000\ \mathrm{m}\mathrm{A}\ \mathrm{h}\ {\mathrm{g}}^{-1} \) compared with \( 340\ \mathrm{m}\mathrm{A}\ \mathrm{h}\ {\mathrm{g}}^{-1} \) of graphite. These high-capacity anode materials normally face poor cycle performance due to severe volume change during the discharge/charge reactions which leads to crack and pulverization. To overcome these limitations, two commonly adopted strategies are nano-engineering and coating with carbon. In this chapter, we have discussed the metal oxides and lithium alloy anodes in three sections, with emphasis on their electrochemical reaction mechanisms with lithium. We have also presented a brief historical review based on the development of the metal oxides and lithium alloys as anode materials for lithium–ion battery, highlighted ongoing research strategies, and discussed the challenges that remain regarding the synthesis, characterization, and electrochemical performance of the materials.

Every market analysis predicts that lithium-ion batteries (LIBs) will dominate energy storage technologies for now and the foreseeable future. LIBs will drive many applications ranging from portable electronics to electric vehicles and smart grids, while also permitting a greener and more sustainable global environment. The few successful cathode materials today are those of the layered, spinel and olivine structures. Despite their success, they still fall short of some requirements (such as high energy, high-rate performance, low cost, cycle life and safety) of modern portable electronics, electric vehicles, grid applications and home storage. For example, it has been well established that the realisation of electric vehicles is highly dependent on LIBs with high energy and power density, durability, safety and reduced cost. In addition, the design, development and innovation of high-performing portable electronics are limited by the size, power and cycle life of the batteries that drive them. Nano-sizing of electrode materials has emerged as one of the most promising strategies to dramatically improve the performance of LIBs, including capacity, rate capability, cycle life, cost reduction and safety. This review chapter provides the readership an understanding of the critical scientific challenges faced by the existing cathode materials used in LIBs and the critical roles engineered nanostructures can play in the realisation of next-generation LIBs for the ever-emerging technologies.

Europium-doped barium aluminate (BaAlxOy:Eu2+) phosphors were obtained at low temperatures (500°C) using the solution — combustion of corresponding metal nitrate-urea solution mixtures. The particle size and morphology and the structural and luminescent properties of the synthesized phosphors were examined by means of scanning electron microscopy (SEM), X-ray diffraction (XRD), Electron diffraction spectroscopy (EDS) and photoluminescence (PL). It was found that the change in Ba: Al molar ratios showed greatly influence not only on the particle size and morphology, but also on their PL spectra and crystalline structure. The structure of BaAlxOy nanophosphors changes from a hexagonal Ba2Al10O17 phase for samples with 6:100 molar ratios to a hexagonal BaAl2O4 one with an increase in Ba content. The peak of the emission band occurs at a longer wavelength (around 615 nm) with a decrease in Ba concentration but displays a broad blue-green emission band composed from two emissions with the maximum at 495 and 530nm coming from Eu2+ in two sites for increasing Ba content. The blue-green emission is probably due to the influence of 5d electron states of Eu2+ in the crystal field because of atomic size variation causing crystal defects while the red emission is due to f - f transitions. These findings clearly demonstrate the possibility of fine tuning the colour emission.