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Summary: In this study, nickel tellurium oxide (Ni3TeO6) was composited with carbon nanotubes (CNTs) through the high‐energy ball‐milling method and proposed as a high‐energy conversion‐type anode for sodium‐ion batteries (SIBs) for the first time. Upon mechanical milling, the Ni3TeO6 nanoparticles were uniformly encapsulated and wedged within the CNTs matrix, which produced a nano/micro hybrid structure. The interconnected CNT network in the composite provided conductive paths for rapid electron transport while effectively suppressing the local stress caused by large volume changes of Ni3TeO6 during the sodiation–desodiation process. The Ni3TeO6@CNTs exhibited a high Na+‐ion storage capacity of 495 mA h g−1, good cycling stability at 200 mA g−1, and high‐rate performance up to 2000 mA g−1. [ABSTRACT FROM AUTHOR]

Summary: Li‐ion batteries (LIBs) are being used extensively in a wide range of applications owing to the facile preparation technology as well as a high energy density, which exceeds those of other commercial batteries. However, LIBs alone cannot satisfy the burgeoning energy demand due to Li‐resource constraints. Recently, K‐ion batteries (KIBs) have garnered the interest of the scientific community as promising alternatives for LIBs due to the abundance of K resources, the affordability of K, and its superior electrochemical properties. However, the development of KIBs is hindered by the slow development of appropriate anode materials that can accommodate the repeated intercalation/deintercalation of large K ions without sustaining significant structural damage. Thus, the development of appropriate anode materials is crucial for the realization of practically viable KIBs. Carbon nanomaterials are promising anode materials due to their remarkable potassiation/depotassiation ability, structural stability, and structural evolution from zero to three dimensions. It is anticipated that an evaluation of the recent advances in carbon and their composites anode materials for KIBs can facilitate the development of practically viable KIBs. This review comprehensively discusses recent developments in carbonaceous and their composites as anode materials for KIBs and provides a prospective for the next research step. [ABSTRACT FROM AUTHOR]

A novel sulfurized carbon decorated by terephthalic acid (TPA) and polyacrylonitrile (PAN), with unprecedently high tap density (≈1.02 g cm−3), is investigated. Room‐temperature sodium–sulfur batteries offer high energy density; however, the dissolution of the polysulfide is a major factor hindering their commercialization. This dissolution problem can be tolerated by inhibiting the formation of polysulfide through binding sulfur to the carbon structure of PAN. Low sulfur content and low volumetric energy density in the composite are other drawbacks to be resolved. Heat‐treated TPA induces a high‐density carbonaceous material with high conductivity. This TPA is partly replaced by PAN, and the produced carbon and sulfur are composited with dehydrated polyacrylonitrile (CS–DPAN), which exhibits higher conductivity and surface area than the sulfurized dehydrated polyacrylonitrile (S–DPAN). The CS–DPAN composite electrode exhibits excellent electrochemical performance, and the resulting volumetric capacity is also superior to that of the S–DPAN material electrode. Operando Raman and operando X‐ray diffraction analyses confirm that the increased capacity is realized via the avoidance of parasitic C60Na3 formation formed below 1 V, by adjusting the operation voltage range. This finding demonstrates the feasibility of carbon–sulfur composites as a high‐energy electrode material for rechargeable sodium batteries. [ABSTRACT FROM AUTHOR]

Potassium ion batteries (KIBs) are attracting great attention as an alternative to lithium‐ion batteries due to lower cost and better global sustainability of potassium. However, designing electrolytes compatible with the graphite anode and addressing the safety issue of highly active potassium remains challenging. Herein, a new concept of using additives to engineer non‐flammable electrolytes for safer KIBs is introduced. It is discovered that the additives, such as the ethylene sulfate (i.e., DTD), can make the electrolyte of 1.0 m potassium bis(fluorosulfonyl) imide in trimethyl phosphate compatible with graphite anode for the first time, without the need of concentrated electrolyte strategies. A new coordination mechanism of additives in the electrolyte is presented. It is shown that the additive can change the K+ solvation structure and then determine the interfacial behaviors of K+‐solvent on electrode interface, which are critical to affect the graphite performance (i.e., K+‐solvent co‐insertion, or K+ (de‐)intercalation). Then, an extremely high potassium storage capability is obtained in graphite electrode for potassium (ion) batteries, particularly the presented high‐performance graphite|K0.69CrO2 full battery fully demonstrates the practical application of this newly designed electrolyte. This additive‐based strategy can offer more opportunities to tune the electrolyte properties and then serve for the more mobile ion battery system. [ABSTRACT FROM AUTHOR]

Layered potassium manganese oxides (K x MnO 2) have been widely investigated as potential cathode materials for K-ion batteries owing to their high capacity and low material cost. However, the K x MnO 2 cathodes generally suffer from unsatisfactory cycle life due to Mn dissolution into the electrolyte triggered by acidic HF corrosion and structural stress at the particle surface during cycling. In this study, we introduce an efficient strategy to stabilize the aggressive chemistry between the organic electrolyte solution and the P′3-type K 0 · 6 MnO 2 (KMO) cathode surface through fluorine treatment. KF-coated P′3-type K 0.6 MnO 1.97 F 0.03 (KMOF-7) is prepared by introducing 7 mol% of ammonium fluoride (NH 4 F) during a pyro-synthesis of K 0 · 6 MnO 2. The partial substitution of F to oxygen atom narrows the interlayer spacing, which helps to reduce the insertion of electrolyte molecules into the crystal structure; meanwhile, the formation of KF coating layer on the cathode surface can suppress the Mn dissolution by protecting KMOF-7 from reacting with HF in the electrolyte solution during charge–discharge processes. This strategy can relieve the structural stress and stabilize the interfacial stability of KMOF-7, thereby, facilitating K+ transportation and depress the charge transfer resistance upon cycling. The KMOF-7 cathode demonstrates the significantly improved cycling stability and power capability compared to KMO. [Display omitted] • Simple NH 4 F treatment enhances the structural and interfacial stability of K 0 · 6 MnO 2. • The partial substitution of F to O atom enhances the structural stability of cathode. • The KF coating layer on the cathode surface can suppress the Mn dissolution. [ABSTRACT FROM AUTHOR]

Aqueous rechargeable batteries (ARBs) are the most dependable energy storage devices (ESDs) due to their tremendous safety and cost-efficiency. The recent invention of the usage of extremely cheaper and high-capacity metallic Mn to construct aqueous manganese ion batteries (AMIBs) shows great promise for the eco-friendly society. However, AMIBs are still in the early stages and their practical utilities need significant achievements on the Mn2+ storing modules. This study demonstrates the competence of a layered-type LiV 3 O 8 (LVO) as cathode material for AMIBs and its reversible electrochemical storage properties of Mn2+ ions. The preliminary electrochemical results (65 mAh g−1 at 5 A g−1 with 88% capacity retention after 9990 cycles and 45 mAh g−1 at 6 A g−1 with 85% capacity retention after 30,000 cycles) are highly encouraging that the layered type materials are the first-choice cathode for AMIBs. • The Mn2+-(de)intercalation storage properties of LiV 3 O 8 cathode is verified. • Mn(ClO 4) 2.xH 2 O.n(OH) y is observed as an electrolyte by-product. • The cycle life failure issues of Mn/LiV 3 O 8 full cell are investigated. [ABSTRACT FROM AUTHOR]

• The PPy-coated Na 1.1 V 3 O 7.9 particles are prepared via microwave-assisted hydrothermal method. • The PPy-coated Na 1.1 V 3 O 7.9 particles are used for Zn-ion battery cathode applications. • The PPy coating enhances electronic conductivity and promotes high ionic diffusion. • The PPy-coated NVO cathode demonstrates enhanced electrochemical properties. The exploration of advanced cathode materials for aqueous rechargeable zinc-ion batteries (ZIBs) is currently a major research topic. In this study, we propose the microwave-assisted hydrothermal synthesis of polypyrrole (PPy)-coated Na 1.1 V 3 O 7.9 (P-NVO) nanorods for the first time as a high-energy and high-power cathode material for ZIBs. The highly conductive PPy surface-coating layer is significant to enhance the electronic conductivity and Zn2+ diffusion kinetics, leading to utilize the V3+/V4+/V5+ multiple redox reactions of the NVO cathode in ZIBs. Compared to the NVO cathode, therefore, the P-NVO cathode offers higher discharge capacity, power capability and cycling stability; in particular, PPy coating triggers the full theoretical capacity of the NVO cathode (527 mAh g−1 with ∼ 3 mol Zn insertion per formula unit) and directly reflects a superior energy density of 408 Wh kg−1. Even at a high current density of 6000 mA g−1, the P-NVO cathode shows unprecedented cycling stability over 1100 cycles without capacity loss. Galvanostatic intermittent titration technique, cyclic voltammetry, in situ X-ray diffraction, and ex situ X-ray absorption near edge structure analyses are combined to verify the superior Zn storage mechanism of the P-NVO cathode. [ABSTRACT FROM AUTHOR]

Solar energy based desalination using solar still is considered as the low-cost efficient method for achieving clean water and the condensation behavior of the still glass cover plays an important role in augmenting the yield. This study aims to improve the water yield and thermal performance of solar still by changing the glass cover wettability using nano-silicon coating through spray technique. Transmission Electron Microscopy image revealed that silicon particles are interconnected and creates a nano-network like structure, whereas the surface area of 45.37 m2/g was exhibited by silicon, signifying its mesoporosity nature. The results showed that the silicon coating changed the condensation behavior of glass cover from film-wise to drop-wise, which augmented the water yield of coated glass solar still by 15.6% as compared to bare glass solar still. Coating durability and ageing analyses revealed marginal reduction in performance and water contact angle of coated solar still even after 100 working days, signifying the durability of coating. The evaporation efficiency of coated glass solar still was 3.6% higher than the bare glass still, owing to the higher heat transfer achieved through drop-wise condensation. Cost analysis of coated solar still revealed freshwater cost per liter of 0.013 US $ with pay-back time of 88 days. Moreover, the water quality analysis of the desalinated water demonstrated excellent quality that is highly suitable for drinking purpose. It is concluded that low-cost and prolonged durability of nano-silicon coating would be highly beneficial in augmenting the overall performance of the solar desalination unit. • Wettability behavior of glass cover was changed using nano-silicon spray coating • TEM image showed that silicon is interconnected and creates nanonetwork structure • Water contact angle were 60° and 113° for bare and silicon-coated glass, respectively • Nano-silicon coating changed the condensation behavior from film-wise to drop-wise • Drop-wise condensation increased water yield of SS by 15.6%, than bare glass SS [ABSTRACT FROM AUTHOR]

• Chromium is doped to improve Na 3 V 2 (PO 4) 3 electrochemical behavior by pyro synthesis. • Self-carbon coating and nano sized particles are gained through this facile technique. • Optimized Na 3 V 1.6 Cr 0.4 (PO 4) 3 cathode shows high capacity and good rate capability. • In situ analysis confirms the gradual phase change in chromium doped Na 3 V 2 (PO 4) 3. Na 3 V 2 (PO 4) 3 (NVP) is characterized by a robust 3D structural framework and a high operating potential; these properties have enabled it to be widely studied as a stable and high-energy density cathode material for sodium-ion batteries (SIBs). In the present study, we designed a Na 3 V 1.6 Cr 0.4 (PO 4) 3 /C (NVCrP@C) cathode by implanting Cr into the crystal structure of NVP and simultaneously coating the surface of NVP with carbon for realizing high power density SIBs. The substitution of Cr to vanadium in the NVP structure significantly enhanced the structural stability of the electrode while the uniform and thin carbon layer improved the electrical conductivity. Interestingly, the NVCrP@C cathode showed high electrochemical activities with multiple V3+/4+/5+ redox reactions triggered by Cr3+ substitution in a wide voltage range (2.5–4.1 V). Consequently, the NVCrP@C cathode delivered excellent cycling stability over 500 cycles even at 15C-rate and power capability up to 70 C-rate. Results from the in-situ X-ray diffraction and ex-situ X-ray absorption near edge structure studies were combined to verify the detailed mechanism of the enhanced sodium storage in the NVCrP@C cathode. [ABSTRACT FROM AUTHOR]

The SARS-CoV-2 virus has spread globally and has severely impacted public health and the economy. Hand hygiene, social distancing, and the usage of personal protective equipment are considered the most vital tools in controlling the primary transmission of the virus. Converging evidence indicated the presence of SARS-CoV-2 in wastewater and its persistence over several days, which may create secondary transmission of the virus via waterborne and wastewater pathways. Although, researchers have started focusing on this mode of virus transmission, limited knowledge and societal unawareness of the transmission through wastewater may lead to significant increases in the number of positive cases. To emphasize the severe issue of virus transmission through wastewater and create societal awareness, we present a state of the art critical review on transmission of SARS-CoV-2 in wastewater and the potential remedial strategies to effectively control the viral spread and safeguard society. For low-income countries with high population densities, it is suggested to identify the virus in large scale municipal wastewater plants before following up with one-to-one testing for effective control of the secondary transmission. Ultrafiltration is an effective method for wastewater treatment and usually more than 4 logs of virus removal are achieved while safeguarding good protein permeability. Decentralized wastewater treatment facilities using solar-assisted disinfestation methods are most economical and can be effectively used in hospitals, isolation wards, and medical centers for reducing the risk of transmission from high local concentration sites, especially in tropical countries with abundant solar energy. Disinfection with chlorine, sodium hypochlorite, benzalkonium chloride, and peracetic acid have shown potential in terms of virucidal properties. Biological wastewater treatment using micro-algae will be highly effective in removal of virus and can be incorporated into membrane bio-reaction to achieve excellent virus removal rate. Though promising results have been shown by initial research for inactivation of SARS-CoV-2 in wastewater using physical, chemical and biological based treatment methods, there is a pressing need for extensive investigation of COVID-19 specific disinfectants with appropriate concentrations, their environmental implications, and regular monitoring of transmission. Effective wastewater treatment methods with high virus removal capacity and low treatment costs should be selected to control the virus spread and safeguard society from this deadly virus. [Display omitted] • Potential secondary transmission of COVID-19 through wastewater is highlighted. • Knowledge of wastewater's role in COVID-19 spread to workers & communities is inadequate. • Potential low-cost on-site methods for virus inactivation in wastewater are proposed. • Solar assisted and micro-algae membrane technologies are sustainable treatment options. • A framework for policymaking and disinfection/deactivation options is presented. [ABSTRACT FROM AUTHOR]

• RGO nanosheet was prepared with specific surface area 167.72 m2 g−1. • RGO with concentration of 4, 8 and 12 wt% were mixed in black paint. • Solar radiation absorption property of absorber increases with increasing RGO wt%. • The water yield of BSS was 3.96 L/m2/day. • 12 wt% RGO doped in black-paint coated absorber show water yield of 5.59 L/m2 /day. The absorber plate of a single basin solar still (SS) is coated by black paint doped with reduced graphene oxide (RGO) nanosheet having a mass fraction of 4–12 wt%, to augment the water yield. The RGO was prepared through hydrothermal treatment to have a specific surface area and mean pore diameter of 167.72 m2.g−1 and 22 nm, respectively. The utilization of 12 wt% RGO doped with black paint-coated absorber enhances the water and absorber temperature by 14.7 and 15.7%, respectively, as compared to only black paint-coated absorber. The accumulated water yield of the SS with (12 wt%) and without the RGO coating was found to be 5.59 and 3.96 L/m2/day, respectively. [ABSTRACT FROM AUTHOR]

• Na 3 V 1.96 Fe 0.04 (PO 4) - Fe 2 P/C cathode reported first time for sodium storage. • Na 3 V 1.96 Fe 0.04 (PO 4) - Fe 2 P/C were synthesized by pyro-synthesis for sodium ion batteries. • The Fe 2 P nano sized particles provides enhanced electrical conductivity. • Na 3 V 1.96 Fe 0.04 (PO 4) - Fe 2 P/C displays a reversible capacity of 84 mA h g−1 at 40C. In this study, we synthesize a carbon-coated Na 3 V 1.96 Fe 0.04 (PO 4) 3 -Fe 2 P composite (NVFP-FP/C) as a cathode material using a one-pot pyro-synthesis method and demonstrate its superior sodium storage performance for sodium-ion batteries. The Na 3 V 1.96 Fe 0.04 (PO 4) 3 -Fe 2 P composite consists of unique nanoclusters of electrically conductive ultra-fine Fe 2 P crystals randomly dispersed among the NVP particles. The presence of Fe 2 P in the composite cathode greatly enhances its electronic conductivity and Na+-ion diffusion co-efficient; hence, the NVFP-FP/C cathode exhibits a high discharge capacity of 103.2 mAh g−1 at 0.1C, remarkable long term cycling stability over 2000 cycles at 20C and excellent power capability up to 40C. [ABSTRACT FROM AUTHOR]

Zinc-ion batteries (ZIBs) are very promising energy storage devices owing to their safety, environmental friendliness, and low-costs. Nevertheless, their development has been mostly focused on aqueous-based systems. We fabricated a quasi-solid-state ZIB based on α-MnO 2 nanohusk morphology synthesized using a one-step hydrothermal method and gel electrolyte. The fabricated quasi-solid-state ZIB exhibited a high initial discharge capacity of 321 mA h g−1 at a current density of 33 mA g−1 and considerable cyclability. We systematically investigated its electrochemical properties utilizing various characterization methods such as cyclic voltammetry and galvanostatic intermittent titration technique. In addition, in-situ synchrotron X-ray diffraction and X-ray absorption spectroscopy were used to elucidate the phase transformation of the cathode in the quasi-solid-state ZIB upon electrochemical cycling. This study may provide further insight into electrochemical behaviour of the quasi-solid-state ZIB based on the α-MnO 2 nanohusk morphology and gel electrolyte as a promising energy storage device. [ABSTRACT FROM AUTHOR]

Lithium-tellurium (Li-Te) batteries are gaining attention as a promising next-generation energy storage system due to their superior electrical conductivity and high volumetric capacity compared to sulfur and selenium. Tellurium's unique properties, such as suitable redox potential, excellent conductivity, high volumetric capacity, and greatest stability, position it as a strong candidate for negative electrode materials. This study explores the potential of metal tellurides, specifically CuTe and FeTe monolayers, as effective tellurium host materials, leveraging their polar interactions with lithium polytellurides. Using density functional theory (DFT) approaches, we investigated the thermodynamic stability, adsorption behavior, and conversion performance of lithium polytellurides on experimentally synthesized metal tellurides. ab initio molecular dynamics (AIMD) simulations confirmed the stability of these materials at 300 °C, 350 °C, and 400 °C. Our findings indicate that the CuTe monolayer provides a strong anchoring effect on lithium polytellurides and exhibits the lowest conversion barrier from Te 8 to Li 2 Te, significantly enhancing electrochemical reaction dynamics and reducing the shuttle effect. Additionally, CuTe demonstrated a low activation energy of 0.297 eV for a key Li 2 Te reaction and strong adsorption energy (-3.511 eV), as well as low diffusion activation energy for Li ions. In addition to the interaction with lithium polytellurides, solvent adsorption studies revealed moderate adsorption energies for CuTe, ranging from -43.435 to -54.297 kJ/mol for solvents like DEC, DMC, DME, DOL, EC, EMC, and PC, suggesting strong, but nondisruptive, binding interactions with electrolyte solvents. Lithium adsorption energies with these solvents, which ranged from -0.359 eV to -0.648 eV, further indicate the stability of the system in typical electrolyte environments. These properties, along with its effective solvent adsorption capabilities, suggest that CuTe is a highly promising candidate for cathode materials in Li-Te batteries. Our results provide valuable insights for the design and optimization of Li-Te batteries, advancing the development of efficient and stable energy storage systems.

Cationic alteration related to a sodium super ion conductor (NASICON)-structured Na 3 V 2 (PO 4 ) 3 (NVP) is an effective strategy for formulating high-energy and stable cathodes for sodium-ion batteries (SIBs). In this study, we altered the structure of NVP with dual cations, namely, Cr and Fe, to develop Na 3 V 1.5 Cr 0.4 Fe 0.1 (PO 4 ) 3 cathodes for SIBs with high-rate capability (∼71 mAh g -1 at 100 C) and an extreme cycle life output (∼75 mAh g -1 with 95% capacity retention for 10,000 cycles). These excellent electrochemical properties can be ascribed to the synergistic effects of Cr and Fe in the NVP structure, as verified experimentally and theoretically. Therefore, the proposed cosubstitution method can enhance the performance of SIBs by improving their structural stability, electronic conductivity, and phase-change behavior.

Among lithium-sulfur (Li-S) battery materials, sulfurized polyacrylonitrile (SPAN) has attracted substantial attention as a cathode material owing to its potential to bypass the problematic polysulfide formation and shuttling effect. Carbonate-based electrolytes have been eschewed compared with ether-based electrolytes because of their poor compatibility with Li metal anodes. In this work, we design and study an electrolyte comprising 0.8 M of lithium bis(trifluoromethanesulfonyl)imide, 0.2 M of lithium difluoro(oxalate)borate, and 0.05 M of lithium hexafluorophosphate in ethyl methyl carbonate/fluoroethylene carbonate = 3:1 v/v solution in the Li-S battery coupled with a Li metal anode and SPAN cathode. The well-designed carbonate-based electrolyte effectively stabilizes both electrodes, delivering high Coulombic efficiencies with stable cyclability. Studies using operando optical microscopy and atomic force microscopy demonstrate that dense, uniform Li deposition is promoted to suppress dendrite growth even at a high current density. Operando Raman spectroscopy reveals a reversible Li + storage behavior in the SPAN structure through the cleavage of disulfide bonds and their redimerization during lithiation and delithiation. As a result, the proposed Li-S battery delivers an overall capacity retention of 73.5% over 1000 cycles, with high Coulombic efficiencies over 99.9%.

Lithium-sulfur (Li-S) batteries using Li 2 S and Li-free anodes have emerged as a potential high-energy and safe battery technology. Although the operation of Li-S full batteries based on Li 2 S has been demonstrated at room temperature, their effective use at a subzero temperature has not been realized due to the low electrochemical utilization of Li 2 S. Here, ammonium nitrate (NH 4 NO 3 ) is introduced as a functional additive that allows Li-S full batteries to operate at -10 °C. The polar N-H bonds in the additive alter the activation pathway of Li 2 S by inducing the dissolution of the Li 2 S surface. Then, Li 2 S with an amorphized surface layer undergoes the modified activation process, which consists of the disproportionation and direct conversion reaction, through which Li 2 S is efficiently converted into S 8 . The Li-S full battery using NH 4 NO 3 delivers a reversible capacity and cycling stability over 400 cycles at -10 °C.

In this article, we report the effect of a Li6 .75 La 3 Zr 2 Al 0.25 O 12 (LLZAO) composite Li(Ni 0.8 Co 0.1 Mn 0.1 )O 2 (NCM811) cathode material on the performance of all-solid-state batteries (ASSBs) with oxide-based organic/inorganic hybrid solid electrolytes. The layered structure of Ni-rich cathode material Li(Ni x Co (1- x )/2 Mn (1- x )/2 )O 2 ( x > 0.6) (NCM) exhibiting a high specific capacity is among the suitable cathode materials for next-generation energy storage systems, particularly electric vehicles and portable devices for all-solid-state batteries. However, the ASSBs present a problem-the resistance at the interface between a cathode and solid electrolyte is larger than that with a liquid electrolyte because of point contact. To solve this problem, using a simultaneous co-precipitation method, we composited various amounts of LLZAO material and an ion conducting material on the cathode material's surface. Therefore, to optimize the value of the LLZAO material in the composite cathode material, the structure, cycling stability, and rate performance of the NCM-LLZAO composite cathode material in ASSBs with oxide-based inorganic/organic-hybrid electrolytes were investigated using powder X-ray diffraction analysis, field-emission scanning electron microscopy, electrochemical impedance spectroscopy, and galvanostatic measurements., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

In this study, magnesium-ion-substituted, sodium-deficient, P3- and P2-layered manganese oxide cathodes (Na 0.67 Mg 0.1 Mn 0.9 O 2 ) 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 Na 0.67 Mg 0.1 Mn 0.9 O 2 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 NaHCO 3 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.

Globally, humanity is facing its most significant challenge in 100 years due to the novel coronavirus, SARS-CoV-2, which is responsible for COVID-19. Under the enormous pressure created by the pandemic, scientists are studying virus transmission mechanisms in order to develop effective mitigation strategies. However, no established methods have been developed to control the spread of this deadly virus. In addition, the ease in lockdown has escalated air pollution which may affect SARS-CoV-2 transmission through attachment to particulates. The present review summarizes the role of graphene nanomaterials, which show antimicrobial behavior and have antiviral efficacy, in reducing the spread of COVID-19. Graphene and its derivatives have excellent antimicrobial efficacy, providing both physical and chemical mechanisms of damage. Coupled with their lightness, optimal properties, and ease of functionalization, they are optimal nanomaterials for coating onto fabrics such as personal protection equipment, face masks and gloves to control the transmission of SARS-CoV-2 effectively. Biosensors using graphene can effectively detect the virus with high accuracy and sensitivity, providing rapid quantification. It is envisioned that the present work will boost the development of graphene-based highly sensitive, accurate and cost-effective diagnostic tools for efficiently monitoring and controlling the spread of COVID-19 and other air-borne viruses.

Lithium-sulfur (Li-S) batteries are considered one of the most promising energy storage technologies, possibly replacing the state-of-the-art lithium-ion (Li-ion) batteries owing to their high energy density, low cost, and eco-compatibility. However, the migration of high-order lithium polysulfides (LiPs) to the lithium surface and the sluggish electrochemical kinetics pose challenges to their commercialization. The interactions between the cathode and LiPs can be enhanced by the doping of the carbon host with heteroatoms, however with relatively low doping content (<10%) in the bulk of the carbon, which can hardly interact with LiPs at the host surface. In this study, the grafting of versatile functional groups with designable properties (e.g., catalytic effects) directly on the surface of the carbon host is proposed to enhance interactions with LiPs. As model systems, benzene groups containing N/O and S/O atoms are vertically grafted and uniformly distributed on the surface of expanded reduced graphene oxide, fostering a stable interface between the cathode and LiPs. The combination of experiments and density functional theory calculations demonstrate improvements in chemical interactions between graphene and LiPs, with an enhancement in the electrochemical kinetics, power, and energy densities., (© 2021 The Authors. Small published by Wiley-VCH GmbH.)

To mitigate a global crisis of Li depletion, potassium-based rechargeable batteries have received significant attention because of their low cost and high specific energy density. In particular, the rechargeable potassium oxygen (K-O 2 ) battery has been recognized as a promising energy storage technology because of its low overpotential and high round-trip efficiency based on the single-electron redox chemistry of potassium superoxide. Despite these merits, research on the development of K-O 2 batteries is still in its early stages owing to a lack of understanding of the fundamental reaction chemistry and the difficulties encountered in handling, in terms of practical acceptability. Hence, it is necessary to summarize the representative works and provide overall insights on K-O 2 batteries and recommendations for future studies. In this Perspective, we critically review the important scientific aspects of K-O 2 batteries, discuss the current challenges encountered, and provide recommendations from the scientific and practical points of view. We hope that this Perspecitve will be helpful in designing innovative and advanced K-O 2 batteries.

Sodium-ion batteries are promising alternatives for lithium-ion batteries due to their lower cost caused by global sodium availability. However, the low Coulombic efficiency (CE) of the sodium metal plating/stripping process represents a serious issue for the Na anode, which hinders achieving a higher energy density. Herein, we report that the Na + solvation structure, particularly the type and location of the anions, plays a critical role in determining the Na anode performance. We show that the low CE results from anion-mediated corrosion, which can be tackled readily through tuning the anion interaction at the electrolyte/anode interface. Our strategy thus enables fast-charging Na-ion and Na-S batteries with a remarkable cycle life. The presented insights differ from the prevailing interpretation that the failure mechanism mostly results from sodium dendrite growth and/or solid electrolyte interphase formation. Our anionic model introduces a new guideline for improving the electrolytes for metal-ion batteries with a greater energy density.

Lithium-ion batteries (LIBs) are widely used in various electronic devices and have garnered a huge amount of attention. In addition, evaluation of the intrinsic properties of LIB cathode materials is of considerable interest for practical applications. Therefore, through first-principles calculations based on the density functional theory, we investigated the structural, electronic, electrochemical, and kinetic properties of mixed transition metals, that is, Ni-substituted LiMnPO 4 (LMP) and LiMnPO 4 F (LMPF) cathode materials, that is, LiMn 0.5 Ni 0.5 PO 4 (LMNP) and LiMn 0.5 Ni 0.5 PO 4 F (LMNPF), respectively, which have not been extensively studied. We also evaluated their delithiated phases, that is, Mn 0.5 Ni 0.5 PO 4 (MNP) and Mn 0.5 Ni 0.5 PO 4 F (MNPF). Our calculations suggest that Ni substitution significantly affected the structural and electrochemical properties. After Li insertion, the MNPF unit-cell volume increased by about 8%, lower than that of pristine MnPO 4 F. The Li intercalation voltage also increased in LMNP (4.27 V) and LMNPF (5.23 V). In addition, the migration barrier was calculated to be 0.4 eV for LMNPF, lower than that of LMPF. This study may provide insights for developing LMNP and LMNPF cathode materials in LIB applications.

Here, we present K 0.28 MnO 2 ·0.15H 2 O, which has a two-dimensional open framework, as an intercalation host for potassium ions. K 0.28 MnO 2 ·0.15H 2 O has a layered structure consisting of edge-sharing MnO 6 octahedra with a large basal spacing of ∼7.3 Å, which facilitates K + -ion mobility. Water molecules in the interlayers between the MnO 2 layers play an important role as a pillar to support the structure during repetitive de/potassiation cycles, as confirmed by an operando X-ray diffraction study. As a result, the large K + ions readily migrate into the crystal structure, resulting in satisfactory electrochemical performance in K-cells. With the aid of the structural pillar, the K 0.28 MnO 2 ·0.15H 2 O cathode delivers a high reversible capacity of 150 mA h g -1 over 100 cycles at a rate of 0.1 C (15 mA g -1 ), with acceptable power capability up to 5 C-rates.

O3-type Na[Ni x Co y Mn z ]O 2 materials are attractive cathodes for sodium-ion batteries because of their full cell fabrication practicality, high energy density, and relatively easy technology transfer arising from their similarity to Li[Ni x Co y Mn z ]O 2 materials, yet their performance viability with Ni-rich composition ( x ≥ 0.6) is still doubtful. More importantly, their capacity degradation mechanism remains to be established. In this paper, we introduce an O3-type Ni-rich AlF 3 -coated nanorod gradient Na[Ni 0.65 Co 0.08 Mn 0.27 ]O 2 cathode with enhanced electrochemical performance in both half-cells and full cells. AlF 3 -coated nanorod gradient Na[Ni 0.65 Co 0.08 Mn 0.27 ]O 2 particles were synthesized through a combination of dry ball-mill coating and columnar composition gradient design and deliver a discharge capacity of 168 mAh g -1 with 90% capacity retention in half cells (50 cycles) and 132 mAh g -1 with 90% capacity retention in full cells (200 cycles) at 75 mA g -1 (0.5C, 1.5-4.1 V). Through analysis of the cycled electrodes, the capacity-degradation mechanism was unraveled in O3-type Ni-rich Na[Ni x Co y Mn z ]O 2 from a structural perspective with emphasis on high-resolution transmission electron microscopy, providing valuable information on improving O3-type Na[Ni x Co y Mn z ]O 2 cathode performance.

P2-type layered oxides have been considered promising candidates as cathodes for sodium-ion batteries (SIBs) owing to their high capacity and high rate capability. However, because of the difficulty involved in forming hierarchical microstructures, it remains challenging to develop high energy density P2-type layered oxides with good electrochemical performance and high electrode density. In this study, we demonstrate the feasibility of P2-type Na 0.65 [Ni 0.17 Co 0.11 Mn 0.72 ]O 2 as a very efficient cathode material for high energy density SIBs by synthesizing a micron-sized hierarchical structure via the coprecipitation route. The as-prepared P2-type microsphere cathode constructed from nanoscale primary particles provides a sufficient interface between the electrodes and the electrolyte solution, which enables to shorten the transport pathways for Na + ions and electrons. Simultaneously, the hierarchical microstructure enhances the structural stability and high tap density (∼1.18 g cm -3 ). Benefiting from these merits, the proposed P2-type microsphere Na 0.65 [Ni 0.17 Co 0.11 Mn 0.72 ]O 2 displays a high discharge capacity of 187 mA h g -1 at 12 mA g -1 and an exceptional cycle retention of 74.7% after 500 cycles, even at the high current density of 600 mA g -1 . In addition, the high tap density of this P2-type microsphere enhances the density of composite cathodes, which translates to a high volumetric energy density of 340 W h L -1 based on the overall volume of the cathode active mass and the aluminum foil current collector.