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In this study, magnesium-ion-substituted, sodium-deficient, P3- and P2-layered manganese oxide cathodes (Na0.67Mg0.1Mn0.9O2) were synthesized through a facile polyol-assisted combustion technique for applications in sodium-ion batteries. The electrochemical reaction pathways, structural integrity, and long cycling ability at low current rates of the P3- and P2-phases of the Na0.67Mg0.1Mn0.9O2 cathodes were investigated using time-consuming techniques, such as galvanostatic titration and series cyclic voltammetry. The results obtained from these techniques were supported by those obtained from operando X-ray diffraction (XRD) analysis. Particularly, the P2-phase provided excellent structural stability owing to its intrinsic crystal structure, thereby exhibiting a reversible capacity retention of 82.6% after 262 cycles at a low rate of 0.1 C; in contrast, the P3-phase exhibited a capacity retention of 38.7% after 241 cycles at a similar current rate. The air stability of these as-prepared powders, which were stored under ambient conditions, was progressively analyzed over a period of 6 months through XRD without conducting any special experiments. The results suggest that in the P3-phase, the formation of NaHCO3 and hydrated phase impurities, resulting from Na+/H+ exchange and hydration reactions, respectively, was likely to occur more quickly, that is, within a few days, compared to that in the P2-phase.

The search for advanced electrode materials in K-ion batteries (KIBs) is a significant challenge due to the lack of an efficient throughput screening method in modern battery technology. Layered oxide cathode materials, KxMnO2, have been widely investigated for KIB application due to their high energy and power density. However, KxMnO2 suffers from structural instability and highly hygroscopic nature. To address these issues, here, a combined machine learning (ML) and first-principles method based on density functional theory (DFT) for screening and experimental validation is developed for the first time. This method is used for designing stable KxMnO2 that can reinforce the structural and environmental stabilities as well as high electrochemical performances. Among the large number of candidates, notably, the ML and DFT-assisted strategies identify P′3-type K0.3Mn0.9Cu0.1O2 (KMCO) as a promising candidate for a high performance KIB cathode. Finally, the experimental protocol proves that the KMCO cathode has substantially improved K-storage properties with high-power density and cycling stability even after four weeks air-exposure period. We believe that this study opens a new avenue for identifying and developing suitable electrode materials for future battery applications.

In this study, magnesium-ion-substituted, sodium-deficient, P3- and P2-layered manganese oxide cathodes (Na

A facile method with one-pot polyol-assisted pyro-technique has been adopted to synthesize highly crystalline, carbon-coated LiMn2O4 (LMO/C) nanoparticles for using as a cathode material in rechargeable Li-ion battery (LIB) applications. this study shows the efficacy of a simple and low-cost pyro-synthesis to realize high performance nano-sized particle electrodes with uniform carbon coating for useful energy storage applications. As using X-ray techniques, we confirmed The phase purity, structure and stoichiometry of the prepared cathode. Electron microscopy studies established that the synthetic technique facilitated the production of nano-sized LMO particles with uniform carbon coating. LMO/C cathode demonstrates excellent electrochemical properties (cycling stabilities of 86% and 77.5% and high rate capabilities of 79% and 36% within the potential windows of 3.3–4.3V and 2.5–4.3V, respectively). The high electrochemical performance of the LMO/C cathode is attributed to the nano-size of the LiMn2O4 particles enabling high surface area and hence greater lithium insertion and also the uniform amorphous carbon coating facilitating effective reduction in manganese dissolution and volume expansion during the lithium de-intercalation/intercalation reactions

Research attention in aqueous rechargeable zinc-ion batteries (ARZIBs) is growing immensely because of their low-cost and eco-friendly cell components. However, its challenging to find new cathode materials towards practical application of ARZIBs. In this contribution, ground-breaking work on the potassium-pillared V2O5.nH2O (K0.5V2O5.nH2O) nanorod with exposed layer structure as high-performance cathode for ARZIB is presented. The storage mechanism of the K0.5V2O5.nH2O cathode in ARZIB is systematically elucidated using a combined of in situ synchrotron X-ray diffraction, ex situ synchrotron X-ray absorption spectroscopy, ex situ TEM analyses, and first-principle calculations. The K0.5V2O5. nH2O cathode displays a notable discharge capacity of 439 mAh g−1 at a current density of 50 mA g−1. Furthermore, it recovers 96% of the capacity after 1500 cycles at 8000 mA g−1. Impressively, the Zn/K0.5V2O5.nH2O battery offers a specific energy of 121 Wh kg−1 at a high specific power of 6480 W kg−1. The superior performance of the cathode is attributed to its unique exposed layer structure with high surface energy, high conductivity, and low migration barrier. The zinc (Zn) insertion pathway into K0.5V2O5.nH2O was studied using density function theory (DFT). This study provides an insight for designing high-performance cathode materials for ARZIBs and other electrochemical systems.

A uniform carbon-coated Na3V2(PO4)2O2xF3 − 2x (NVPOF/C) nanoparticle synthesized by a novel pyro synthesis method is utilized for sodium-ion batteries (SIBs) as a cathode. Remarkably, the electrochemical properties are performed at high rates show significantly improved discharge capacity (Fig. 1). At 0.1 C, the NVPOF/C cathode shows a discharge capacity of 130 mAh g− 1, corresponding to 100% of the theoretical capacity. Even at 50 C, a discharge capacity of ~85 mAh g− 1 could be attained. The in situ X-ray diffraction and ex-situ synchrotron X-ray absorption near edge structure spectroscopy results exposed that the reversible sodium ion insertion/ extraction into/from NVPOF/C host structure occurs with a small volume change (3.4%), indicating the structural stability of the cathode. Our study validates that the Na3V2(PO4)2O2xF3 − 2x/C electrode is a promising candidate for developing high power/ energy density cathodes for SIBs. Figure 1. (a) Galvanostatic charge/discharge potential profiles of Na3V2(PO4)2O2xF3-2x in the potential range of 2.0 ~ 4.3V at 0.1C. (b) Cycle performance at 1C. (c) The discharge profiles of different C. (d) Comparison of the rate capabilities at various curve Figure 1

Energy storage devices remain critical to meet the increasing demands of the modern society. Rechargeable lithium ion batteries (LIBs) are a crucial finding in this century to compensate the energy demand in the present day. As device performance is intimately correlated with the material properties, production of functional energy storage nanomaterials endowed with exceptional physico-chemical properties in view of their particle-size confinement has become critically significant. Low- or moderate-temperature synthetic strategies that are versatile, easily scalable, and efficiently produce size-tuned and efficient materials are essential. In the recent past, combustion-based synthetic process has emerged as one of the promising strategies for developing customized energy storage nanomaterials due to rapid synthesis and ease of preparations in a large scale, etc. In the present review, the advancements in the design and chemistry of these strategies in developing a wide range of high voltage cathode materials for LIBs have been discussed. Among the various combustion techniques, this study will focus mainly on solution combustion, sol-gel based combustion and polyol-based pyro-synthesis. The versatility of these processes to provide tailored particle morphologies and particle sizes at the nanoscale and their effects on the material performance in various applications, particularly in energy storage, is also discussed.

The energy used by buildings occupies 38% of the entire energy usage in Korea, of which lighting consumes 22% in considerable amount. Accordingly, various tests and researches to reduce energy consumed by buildings, especially consumption of indoor lighting energy have been constantly carried out. This study has suggested a light shelf system applied with user awareness technology and lighting dimming control system on the basis of light shelf system, user awareness technology and lighting control, and verified energy reduction efficiency by comparing results of energy reduction performance evaluation for the suggested light shelf. In order to verify energy reduction of the suggested system, a test bed has been utilized, energy consumptions have been calculated for 3 types including user unawareness and lighting On/Off control light shelf system, user awareness and lighting On/Off control light shelf system, user awareness and lighting dimming control light shelf system, and users have been set to User A, User B, and User C for family members of 60s, 40s, and 10s. The results are shown below. 1) Lighting energy consumption for user awareness technology and lighting On/Off control applied movable type light shelf system showed 105%, 55%, and 20% for User A, User B, and User C comparing to user unawareness and lighting On/Off control applied fixed light shelf system and in the case of User A, it has increased energy usage and is inappropriate. 2) Lighting energy consumption for user awareness technology and lighting dimming control applied movable type light shelf system showed %, 13%, and 6% for User A, User B, and User C comparing to user unawareness and lighting On/Off control applied fixed light shelf system, and allowed efficient energy reduction. This study is significant from an aspect that it has suggested an alternative to energy shortage problem by applying user awareness technology and lighting control technology and verifying effectiveness of energy reduction in order to improve lighting performance and energy efficiency of the light shelf.

Nowadays, building energy management is more important than ever. Especially, lighting energy used in the building occupies 30% of the whole consumed energy. Therefore, reducing the consumption of lighting energy could bring effective energy saving. As the system configuration, the sum of distance between the window and the light shelf reflector and width of light shelf is set to be 500 mm at maximum. The horizontal width of light shelf is set between 200 mm, the angle of light shelf is set between -90 and 90, and the horizontal distance between the window and the light shelf reflector is set between 0 mm and 300 mm in consideration of sum of width of light shelf. The light shelf system suggested in this study can be used as the basic design data for various design elements in a building.

The energy consumption in buildings accounts for approximately 40% of total energy consumption in the world. The light-shelf system is suggested as a measure to reduce energy consumption in buildings, and the test bed is used for evaluating the performance of suggested light-shelf system. The result of this study can be used as the preliminary data for design to install the internal light-shelf by improving the efficiency of light-shelf through the proper location and angle of light-shelf indoors.

Due to a global energy problem, there is a rising interest in energy saving around the world, and the lighting energy used in buildings accounts for 22% to 28% of total energy used in buildings. Therefore, reducing the consumption of lighting energy could bring effective energy saving. The purpose of this study is to suggest the light shelf system according to the distance with the skylight that could reduce lighting energy consumption. The system suggested in this study is the system that improves the unfamiliarity of simple fixed light shelf while reducing lighting energy consumption by applying different width and angle of light shelf as well as a different distance between the light shelf and the skylight. It is possible to evaluate the energy performance for each season through the full-size test-bed that could realize actual housing conditions for 24 hours a day, 365 days a year to find an appropriate value so that indoor daylight distribution can be confirmed and the consumption of lighting energy used in indoors can be reduced. The light shelf system suggested in this study can be used as the basic design data for various design elements in a building.

Energy used in buildings takes up 38-39% worldwide, among which lighting accounts for 22-28%. If lighting energy consumption is reduced globally, it is possible to accelerate energy saving. Thus, this study aims to propose a light shelf system among natural lighting systems to save lighting energy. The light shelf system proposed by this study is a system that can cope with the changes of light shelves according to the weight lightening of buildings through the width of the light shelf and the separation distance between skylight and light shelf reflector. To evaluate performance for energy saving, this study conducted seasonal energy performance evaluation through a real-scale test bed in which round-the-clock and year-round implementation is possible. This can reduce the use of indoor lighting energy by effectively bringing indoor light. This light shelf system can directly cope with the formational changes of light shelves due to weight lightening, which can also be used as a foundation for design to apply to changes in various buildings.