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P2-type Fe/Mn-based oxides are considered as the competitive cathode materials for sodium-ion batteries because of high specific capacity and low material cost. However, it suffers from poor cycling stability and unsatisfactory rate capability. Herein, the lithium-doped Na 0.67 Li 0.1 Fe 0.4 Mn 0.5 O 2 microspheres are successfully synthesized via a three-step method. Benefiting from the synergetic effect of the double modification through the morphology controlling and lithium doping, the Na 0.67 Li 0.1 Fe 0.4 Mn 0.5 O 2 delivers an improved cycling stability and rate performance. Moreover, fluorine is successfully introduced to further improve the electrochemical performance of the Na 0.67 Li 0.1 Fe 0.4 Mn 0.5 O 2. Fluorine doping can boost the stability of the material crystal structure because of the strong electronegativity of fluorine and the stable fluorine-metal bond. Meanwhile, fluorine doping avoids the formation of extra O3 phase by reducing the average valence of transition metals. Most importantly, P2-type 10 mol% F-Na 0.67 Li 0.1 Fe 0.4 Mn 0.5 O 2 shows a high discharge specific capacity of 182.0 mAh g-1 at 20 mA g-1, excellent capacity retention of 90.0% after 50 cycles and outstanding rate performance of 128.7 mAh g−1 at 400 mA g-1. Apparently, such a modification strategy apparently promotes the electrochemical performances of the P2-type Fe/Mn-based oxide and increases the commercial application possibilities of this cathode material in sodium-ion batteries. • P2/O3-type Li-doped NLFMO microspheres are successfully synthesized. • NLFMO microspheres delivers improved cycling stability and rate performance. • Pure P2-type NLFMO microspheres are synthesized by 10 mol% fluorine doping. • P2-type 10 mol% F-NLFMO displays higher specific capacity than NLFMO. • P2-type 10 mol% F-NLFMO also shows better cyclic stability and rate capability. [ABSTRACT FROM AUTHOR]

As one of important indicators of atherosclerosis (AS), excess homocysteine (Hcy), could cause oxidation stress, thus leading to inflammation and tissue damage. Hypochlorous acid/hypochlorite (HOCl/OCl−), as an important reactive oxygen species, is speculated to be an indicator of AS caused by Hcy-inducated. Here, a fluorescence nanoprobe LR NPs based on the assembly of pluronic F-127 and probe TR was developed for ClO− detection and imaging during Hcy stress. As expected, LR NPs showed good selectivity and sensitivity for ClO− detection. LR NPs can visualize the fluxes of HClO/ClO− during the stimulation of Hcy induce AS in real time, which demonstrated HClO/ClO− could be performed as an indicator of AS. [Display omitted] • A nano-fluorescent probe (LR NPs) with high sensitivity and selectivity to ClO− was designed and synthesized. • LR NPs was applied to detect endogenous and exogenous ClO− in living cells. • The fluorescent imaging of ClO− caused by Hcy-induced was reported for the first time. [ABSTRACT FROM AUTHOR]

• Compact porous Si@graphene layered structure with improved contact interface and adequate interconnected pores were prepared by a facile hydrothermal method. • The improved Si/graphene contact interface can promote the positive effect of graphene on restraining the volume change and thus enhance the structural stability during repetitive cycling. • The closely wrapping graphene and interconnected pores simultaneously provide adequate paths for fast transfer of electrons and ions, resulting in greatly improved dynamic performance. Si/carbon composites are attractive anode materials for rechargeable Li-ion batteries (RLIBs), which combine the advantages of Si and graphene. Designing special Si/carbon structure with intimate contact interface and abundant void space for fast ion transmission is an effective strategy for enhancing cyclability and rate performance of the electrode materials. Inspired by the structure of fishnet, here we fabricate a binder-free and self-standing Si@porous-graphene (Si@PGN 60) composite with nano silicon particles encapsulated in porous graphene sheets. The obtained Si@PGN 60 sample exhibits many favourable features for high performance Si/carbon anodes, including improved Si/graphene contact interface, and abundant void space for fast ion transmission. Tanks to the unique structure, the resultant Si@PGN 60 anode presents remarkably improved capacity reaching 1839.9 mA h g−1 at 300 mA g−1, and excellent cycling performance (734 mA h g−1 at a high current density of 3000 mA g−1). Here we fabricate a binder-free and self-standing Si@graphene (Si@PGN 60) composite with silicon encapsulated in porous graphene sheets. The obtained Si@PGN exhibits many favourable features for high performance Si/carbon anodes, including improved contact interface between Si and graphene, and abundant void space for fast ion transmission. Tanks to the unique structure, the resultant Si@PGN presents not only remarkably improved capacity reaching 1839.9 mA h g−1 at 300 mA g−1, but also superior rate performance of 734 mA h g−1 at a relatively high current density of 3000 mA g−1. [Display omitted] [ABSTRACT FROM AUTHOR]

With the quick development of electric vehicles and grid energy storage, the demand and production of lithium ion batteries (LIBs) are rapidly increasing, and the problem of lithium resource shortage becomes more and more serious. Both in terms of economic value and environmental protection, the recycling and regeneration of the spent lithium batteries is extremely urgent. Herein, a green and efficient hydrothermal technique for direct regeneration of spent lithium iron phosphate (LiFePO 4 or LFP) was proposed. LFP loses the partial lithium during the long cycle and converts to FePO 4 (FP), therefore, the replacement of the lost lithium is crucial for the regeneration of spent LFP. Herein, the effects of hydrothermal conditions such as reaction temperature, Li+ concentration and reducing agent concentration on the performance of product are systemically studied. Besides, it has been found that the control of hydrothermal condition is conductive to the supplement of Li and the enhancement of electrochemical performance of the product. Under hydrothermal conditions of 200 °C for 3 h, the regenerated LFP shows the optimal electrochemical performance of 165.9, 151.93, 145.92, 133.11 and 114.96 mAh g−1 at 0.1, 0.5, 1, 2, and 5 C, respectively. In addition, the capacity retention is as high as 99.1% after 200 cycles at 1 C. Therefore, this work provides a new idea for the direct regeneration of spent LFP cathode materials. [Display omitted] • Spent LiFePO 4 was repaired by a green and efficient hydrothermal process. • Fe3+ in S-LFP was reduced to Fe2+ by tartaric acid. • Soluble Li+ salt can adequately contact with the spent LFP in hydrothermal process. • The lithium defect in the spent LFP is well repaired. • The repaired materials of R-LFP-700 exhibit excellent electrochemical properties. [ABSTRACT FROM AUTHOR]

• Activated carbon nanotubes (ACNTs) possess plentiful active sites. • ACNTs as conductive support to deposit NiS and alleviate particles agglomeration. • The nanostructured NiS/ACNTs composite possesses outstanding performances. • The effects of electrolyte concentration on the NiS/ACNTs electrode are studied. • The NiS/ACNTs//AC ASCs delivers high energy density and power density. [Display omitted] Hexagonal nickel sulfide is extensively studied and used for supercapacitors due to its high theoretical specific capacitance (1060 F g−1), simple synthesis craft and low cost. However, the poor electrical conductivity and easy agglomeration severely restrict its practical application. Herein, we design the composite materials of the nickel sulfide nanoparticles and activated carbon nanotubes (NiS/ACNTs) with plentiful active group by hydrothermal method and subsequent annealing treatment, thus effectively inhibiting the agglomeration of NiS nanoparticles and producing good supercapacitor behaviors. Benefiting from the superiority of composite structure, the NiS/ACNTs hybrid electrode delivers a high specific capacitance of 1266 F g−1 at a current density of 1.0 A g−1 and sustains a capacitance value of 1028 F g−1 at 10 A g−1 (81% of initial specific capacitance). Moreover, the asymmetric supercapacitors (ASCs) with NiS/ACNTs cathode and activated carbon (AC) anode exhibit a high energy density of 36.0 Wh kg−1 at a power density of 806 W kg−1 and a good capacitance retention of 83% after 2000 cycles at 2.0 A g−1. Therefore, the combination of the battery-type materials and carbon materials will a significant exploration to solve particle agglomeration and develop the high electrochemical performance ASCs. [ABSTRACT FROM AUTHOR]

• Polypyrrole coating is utilized for polysulfides immobilization. • Lithium sulfide is wrapped inside cathode from exposure. • Activation barrier and polysulfides shuttle are greatly suppressed. • Electrochemical performances of as-prepared cells are promoted. The significantly-high theoretical energy density and eco-sustainability of lithium sulfur batteries (LSBs) arouses a rapid surge of interest in recent years. However, some key issues of cathode, for instance, the polysulfides confinement, low ion/electrons transfer and etc., hinder the practical utilization of LSBs. Herein, such issues could be carefully handled by using the conductive polypyrrole as polysulfides wrapper. The polypyrrole with pyrrole rings can efficiently confine polysulfides inside cathode for redox. Meanwhile, the conductive polypyrrole with delocalized π-electron cloud can facilitate electrons transfer. Besides, the addition of carbon nanotube (CNT) and oxidized graphene (GO) can enhance the conductivity of cathode material. As a result, the Li 2 S/CNT/GO/PPy cathode delivers a cycling capacity of 525 mAh g−1 with a low-capacity decay rate of 0.065 % cycle−1 after 400 cycles. Therefore, the lithium-sulfur battery with Li 2 S-based and PPy-wrapped cathode could reasonably be counted as a potential alternative of long-cycling Li-ion cells. [Display omitted] [ABSTRACT FROM AUTHOR]

• Four types of Si/G composites with the same components and different combination ways are prepared by simple methods. • Four types of Si/G composites are prepared to study the internal factors affecting the initial coulombic efficiency. • The Si-G@C with large specific surface area still owns the highest initial coulombic efficiency. Investigating the internal factors that affect the initial coulombic efficiency (ICE) of silicon/graphite (Si/G) composites and improving ICE are critical to promote applications of Si/G composites in lithium-ion batteries. Here, four types of Si/G composites are prepared with different specific surface area, Si–G phase interface and charge transfer impedance (R ct) to study the internal factors affecting the ICE of Si/G composites. The experimental results show that the influencing factors on ICE of Si/G composites are not only specific surface area, but also the Si–G phase interface and R ct. During the first lithiation process of Si/G composites, there are some reversible phase (Li x Si, Li x C) and irreversible phase (Li 2 O, Li 2 SiO 4 and organolithium) formed, the ICE of Si/G composites is mainly determined by the irreversible phase. The specific surface area, R ct and Si–G phase interface can affect the reaction kinetics of the materials and the ratio of reversible/irreversible phase content, which ultimately affect the ICE of Si/G composites. A smaller specific surface area and well Si–G phase interface with a low R ct will bring a higher ICE of Si/G composites. This report may provide a new idea for the research of ICE of Si/G composites and promote their practical application. The Si–G, Si–G@C, Si@C–G and Si@C–G@C composites are prepared with different specific surface area, Si–G phase interface and charge transfer impedance (R ct) to study the internal factors affecting the ICE of silicon/graphite composites. The Si–G@C with large specific surface area still owns the highest ICE, due to the well Si–G phase interface and a low R ct , which can affect the reaction kinetics to generate more reversible phase (Li x Si, Li x C) and less irreversible phase (Li 2 O, Li 2 SiO 4 and organolithium). Image, graphical abstract [ABSTRACT FROM AUTHOR]

The high theoretical energy density, high environmental adaptability and safety of lithium sulfide (Li 2 S)-oriented cathodes attract enough attention among lithium-sulfur batteries (LSBs). In this work, the lithium sulfide (Li 2 S)-oriented composite is fabricated via an in-situ carbothermic reduction method, in which lithium sulfate is reduced by CMK3 at an optimized temperature and subsequently the as-prepared Li 2 S is protected via the conformal carbon layer by carbonization of phenol-formaldehyde resin (PF). With the aid of the porous carbon structure of CMK3 and protection of PF-derived conformal carbon layer, the dispersity of Li 2 S and conductivity of cathode are availably enhanced. It has been found that the Li 2 S@CMK3-C prepared at optimum carbothermic reduction temperature of 835 °C has excellent electrochemical performance. The lithium-sulfur battery using Li 2 S@CMK3-C as cathode and metal Li as anode can deliver a high initial discharge capacity of 979 mAh g−1 at 0.1 C, the capacity retention after running at various current density is 94%, and the discharge specific capacity is still 530 mAh g−1 at 2 C after 450 cycles. Therefore, the preparation of CMK3-supported Li 2 S-based cathode material provides a new approach for the development and industrialization of new high-performance Li–S battery. Image 1 • An in-situ carbothermic reduction method is employed. • Lithium sulfide is in-situ formed inside cathode matrix as sulfur source. • The shuttle of polysulfides and activation energy barrier is suppressed. • The as-fabricated batteries deliver elevated electrochemical performance. [ABSTRACT FROM AUTHOR]

Oriented construction of high-performance mesoporous TiNb 2 O 7 (m-TNO) is important to the design innovation of anode material for next-generation lithium-ion batteries (LIBs) due to the high capacity and long cyclic life of m-TNO. However, the conductivity enhancement of m-TNO and thus accelerating Li+ transfer is still the key point to realize its practical application in LIBs. In this work, a synergistic strategy based on the single-core/dual-shell m-TNO@TiC@NC hierarchical structure is put forward, which is achieved by using m-TNO as host architecture as well as TiC and N-doped carbon layer (NC) as dual-shell layers. The results show that the m-TNO@TiC@NC hierarchical structure can not only provide an integrated conductive network to improve the conductivity of m-TNO, but also can establish a reinforced structure to maintain the anode stability. Besides, it is found that the m-TNO@TiC@NC composite has a high capacity of 328.6 mAh g−1 at 0.5 C after 200 cycles and a high-rate capacity of 186.4 mAh g−1 at 5 C by galvanostatic discharge-charge tests. Therefore, this kind of special single-core/dual-shell structure design can convincingly enhance the conductivity of m-TNO and facilitate the Li+ transfer rate, thus promoting electrochemical performances of LIBs due to the synergistic effect of dual-shell layers. Image 1 • The m-TNO@TiC@NC composite is achieved by using m-TNO as host architecture as well as TiC and NC as dual-shell layers. • The m-TNO@TiC@NC composite shows the single-core/dual-shell hierarchical structure. • The new-type ceramic material TiC is used as conducting layer. • The m-TNO@TiC@NC composite displays good electrochemical performance. [ABSTRACT FROM AUTHOR]