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We report a general method for selective cross‐coupling of α,β‐unsaturated carboxylic acids with aryl tosylates enabled by versatile Pd(II) complexes. This method features the general cross‐coupling of ubiquitous α,β‐unsaturated carboxylic acids by decarboxylation. The transformation is characterized by its operational simplicity, the use of inexpensive, air‐stable Pd(II) catalysts, scalability and wide substrate scope. The reaction proceeds with high trans selectivity to furnish valuable (E)‐1,2‐diarylethenes. [ABSTRACT FROM AUTHOR]

The chemical binding between metal compounds and polysulfides provides a good solution to inhibit shuttle effect in Li‐S batteries. However, the Sabatier principle predicts that overly strong adsorption will commonly hinder the conversion of polysulfides, so building the synergetic effect mechanism between "strong adsorption" and "fast conversion" for polysulfides is a significant strategy. To realize this goal, in this study, the defect‐enriched Co9S8 hollow prisms (DHCPs) as both S host and catalyst material for Li‐S batteries are designed. Based on in situ UV–vis spectroscopy results, it is found that DHCPs can profitably promote the generation of S3·−${\rm{S}}_3^{\cdot{\bm{ - }}}$ radicals during the discharge process. In the case of the relatively high conversion barrier of "liquid–liquid" reaction, the generated S3·−${\rm{S}}_3^{\cdot{\bm{ - }}}$ radicals are responsible for the fast conversion reaction via a unique reaction pathway. When the sulfur loading is 4.63 mg cm−2, the cell with DHCP/S cathode delivers a high areal capacity of 4.75 mAh cm−2 at 0.1 C and keeps a high capacity of 2.99 mAh cm−2 after 100 cycles at 0.5 C. This study provides a positive attempt to achieve "strong adsorption" and "fast conversion" of polysulfides simultaneously, which will convincingly boost the development and practical process of Li‐S batteries. [ABSTRACT FROM AUTHOR]

[Display omitted] Benefiting from the extra contribution of O redox, Co-free Li-rich layered oxides (LRNMO) can satisfy the requirement of high specific capacities. However, during the high-voltage charging process, lattice oxygen being oxidized to O− or O 2 leads to a gradual transition of the structure from layered to spinel phase, capacity and voltage decline, hindering the practical application of LRNMO in the lithium-ion battery. Here, a surface modification strategy of Li 1.2 Ni 0.32 Mn 0.48 O 2-δ doped with Ta5+ ions is proposed, in which the Ta5+ ions occupy the lithium sites of the lattice structure on the surface layer of LRNMO and form a Ta 2 O 5 coating layer. The modified electrode exhibits excellent rate performance and cycling stability, with 94.9% and 85.5% capacity retention rate and voltage retention rate, respectively, after 200 cycles at 1C. Moreover, the initial coulomb efficiency and ionic conductivity of the modified electrode are also apparently enhanced. Simultaneously, the decreased Li/Ni mixing degree of the modified electrode reflects the improvement of the structural stability. Therefore, the modification strategy through strong metal–oxygen bonding to integrate the surface structure to regulate the oxygen activity provides a new direction for the design of high energy density Co-free Li-rich cathode materials. [ABSTRACT FROM AUTHOR]

[Display omitted] Benefiting from the extra contribution of O redox, Co-free Li-rich layered oxides (LRNMO) can satisfy the requirement of high specific capacities. However, during the high-voltage charging process, lattice oxygen being oxidized to O− or O 2 leads to a gradual transition of the structure from layered to spinel phase, capacity and voltage decline, hindering the practical application of LRNMO in the lithium-ion battery. Here, a surface modification strategy of Li 1.2 Ni 0.32 Mn 0.48 O 2-δ doped with Ta5+ ions is proposed, in which the Ta5+ ions occupy the lithium sites of the lattice structure on the surface layer of LRNMO and form a Ta 2 O 5 coating layer. The modified electrode exhibits excellent rate performance and cycling stability, with 94.9% and 85.5% capacity retention rate and voltage retention rate, respectively, after 200 cycles at 1C. Moreover, the initial coulomb efficiency and ionic conductivity of the modified electrode are also apparently enhanced. Simultaneously, the decreased Li/Ni mixing degree of the modified electrode reflects the improvement of the structural stability. Therefore, the modification strategy through strong metal–oxygen bonding to integrate the surface structure to regulate the oxygen activity provides a new direction for the design of high energy density Co-free Li-rich cathode materials. [ABSTRACT FROM AUTHOR]

A new efficient route for the synthesis of 2-chloro-2';-deoxyadenosine (Cladribine), CdA) has been developed. The key step of this method was selective deprotection of the acetyl group at the 2' position; the 3', 5' acetyl groups were not affected. This can be accomplished efficiently with hydroxylamine hydrochloride and sodium acetate in pyridine. The 2' hydroxyl group was removed by the Barton-McCombie reaction. Using this strategy, CdA was prepared in five steps and 31.0% yields. [ABSTRACT FROM AUTHOR]

In this work, the function of 4-nitroimidazole (4-NIm) in the formation of Cr-MIL-101 was confirmed. It was found that 4-NIm is an effective additive in the formation of Cr-MIL-101 synthesized at lower temperature. The investigation of crystallization time showed that 4-NIm can prevent Cr-MIL-101 phase converting into Cr-MIL-53 phase. The effect of concentration of 4-NIm on the morphology and the yield of Cr-MIL-101 may therefore be explained by increasing the nucleation rate. The investigation of crystallization temperature revealed that 4-NIm changes the synthesis temperature range of Cr-MIL-101 into 423–463 K. The assistant function of 4-NIm was played through interaction with H + and NO 3 − in the synthesis system, which may lead to enhancement of the deprotonation of H2BDC. Throughout the investigation of crystallization time, crystallization temperature and content of 4-nitroimidazole, the function of 4-nitroimidazole as an effective additive in the formation of Cr-MIL-101 synthesized at lower temperature was confirmed. [ABSTRACT FROM AUTHOR]

Ce-UiO-66 was firstly used as a supercapacitor electrode material and exhibited a high capacitance of 6.9 Fcm−2 in a redox electrolyte. A novel self-supported structure of Ce-UiO-66/TNF was firstly synthesized by growing Ce-UiO-66 on a TNF substrate. This novel Ce-UiO-66/TNF material was proved to possess a high supercapacitive performance in the redox electrolyte of Fe(CN) 6 3−/4−, and it was also the first study for Ce-UiO-66 material on the supercapacitor application. High specific capacitances of 6.9 and 2.5 Fcm−2 can be achieved at large current densities of 20 and 80 mAcm−2, respectively. After 10,000 charge-discharge cycles, the capacitance retention can be kept at 95% and the coulomb efficiency can be maintained over 98%. Such outstanding electrochemical performance may be related to the redox property of the electrolyte, high specific surface area of the Ce-UiO-66 material, porous characteristic of the TNF substrate and self-supported structure of the whole electrode. [ABSTRACT FROM AUTHOR]

• The metal phosphates coated P3-NaMN is synthesized via co-precipitation route. • The modified samples show a great improvement of cycling performance. • The metal phosphates coating could promote the air stability of the materials. • The coated layer could inhibit the loss of lattice oxygen in high voltage region. Cathode materials are considered to be the most critical component of the sodium-ion batteries, which determine the overall electrochemical performance of the battery to some degree. Currently, the layered oxides receive significant attention due to the high operating voltage and high capacity. However, the instability in the air and unsatisfactory cycling performance limit their commercial application. Based on excellent electrochemical performance of the P3-type Na 0.65 Mn 0.75 Ni 0.25 O 2 material, here AlPO 4 and Mg 3 (PO 4) 2 protective coatings are employed to modify P3-type Na 0.65 Mn 0.75 Ni 0.25 O 2. The metal phosphate layers cover the surfaces of the pristine particles via a co-precipitation route. It has been found that the two modified samples exhibit an obvious improvement of cycling performance with the capacity retentions about 93% at a current density of 0.2 C within 100 cycles. In addition, the coated metal phosphate layer can effectively suppress the irreversible oxidation of oxygen in the high voltage redox region. Furthermore, after exposure to the air, the coating samples still retain a high electrochemical activity. Therefore, the metal phosphates coating provides a meaningful exploration for the research and development of long-term cycling life and high air stability of cathode materials in sodium-ion batteries. [ABSTRACT FROM AUTHOR]

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]

Abstract Graphene paper is a promising electrode material for use in flexible supercapacitors due to its good electronic conductivity and excellent mechanical characteristics. However, layers of graphene paper have a strong tendency to restack, resulting in a seriously reduced specific surface area and limited electrochemical performance. In this paper, restacked layers of graphene paper are reopened by a vacuum-assisted method, and carbon nanotubes (CNTs) are directly deposited on the enlarged space between the opened graphene layers. Consequently, an ordered carbon composite structure with alternately arranged graphene sheets and CNTs is constructed and exhibits increased specific surface area and a 3D conductive network. The structure and morphology of the samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman spectroscopy and N 2 adsorption/desorption measurements. The electrochemical performance was tested by galvanostatic charge-discharge test (GDC), electrochemical impedance spectroscopy (EIS) and cyclic voltammograms (CV). The obtained graphene/CNT paper exhibits a remarkably improved capacity of 170.8 F g−1, which is nearly two times higher than that obtained for a regular graphene paper. Highlights • A unique carbonaceous structure with CNTs depositing between the opened layers of graphene is established. • The reopening of the graphene layers can enlarge the layer distance and increase the SSA. • The deposited CNTs can further inhibit the restacking of graphene layers and form a 3D conductive framework. • The prepared MGCP exhibits significantly enhanced electrochemical performance. [ABSTRACT FROM AUTHOR]

The hollow Si nanospheres modified by the mechanically robust titanium dioxide (TiO 2 ) shell and the uniform carbon layer are intentionally designed and successfully prepared as the anode active material of high performance lithium-ion batteries. The effects of the robust TiO 2 shell and the uniform carbon layer on the structure and electrochemical performances for the Si@TiO 2 @C nanospheres are studied in detail by X-ray photoelectron spectroscopy, transmission electron microscopy, X-ray diffraction and charge/discharge tests. The results show that the hollow structure of the Si core can spontaneously absorb the huge volume expansion stress, the robust TiO 2 shell is used as a compact fence to promote the expansion towards the interior of the Si cavity instead of the exterior in the processes of charge/discharge, and the uniform carbon layer can effectively enhance the electrical conductivity and further control the integrity and stability of the well-wrapped core-shell-shell framework. Typically, the resultant hollow Si@TiO 2 @C nanospheres exhibit a high initial discharge capacity of 2557.1 mAh g −1 with coulombic efficiency of 86.06% as well as a large recuperative discharge capacity of 1270.3 mAh g −1 after 250 cycles at 1 A g −1 with a mean coulombic efficiency of 99.53%. Therefore, the hollow Si@TiO 2 @C nanospheres prepared by one-step sol-gel coating process show outstanding electrochemical properties and are considered as a prospective candidate to the adhibitions of the anode material for new generation power LIBs. [ABSTRACT FROM AUTHOR]

[Display omitted] • Probe is capable of detecting ONOO− with a longwave fluorescence emission. • TL could monitor high concentration of dexamethasone-induced an up-regulation of ONOO−. • Probe has mitochondrial targeting capability. • Probe have good selectivity and low detection limit. • The imaging demonstrated its value of practical application. Peroxynitrite (ONOO−), as a strong oxidizing reactive nitrogen substance (RNS), is generated endogenously by cells. Its visualization research is crucial to understand relevant disease processes. Herein, we reported a long-wavelength mitochondria-targeted fluorescence "turn on" probe TL. The probe TL could react with ONOO− by using 4-(Bromomethyl)benzeneboronic as a reactive site, which exhibited outstanding characteristics for detection of ONOO−, thus improving response time (about 50 s), sensitivity (DL, 10.1 nM), and emission wavelength (667 nm). Besides, TL displayed well mitochondria targeting and biological visualizing of exogenous and endogenous ONOO− in biological systems. Finally, TL was used to monitor high concentration of dexamethasone-induced an up-regulation of ONOO−. This indicated that TL has excellent potential to study the fluctuation of ONOO− in the physiological and pathological system. [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]

Graphene aerogel is one of the most promising candidates for supercapacitors electrode material because of its high specific surface area and good electronic conductivity. However, the extremely low gravimetric density seriously limits its further practical applications. In this paper, a compression strategy was utilized to increase the gravimetric density by forming a unique highly-curved carbon nanotubes supported graphene porous 3D layer structure. The structure and morphology were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman spectrum and N 2 adsorption/desorption measurement. Results demonstrate that the highly-curved carbon nanotubes between the graphene layers can prevent the restacking of the graphene layers. The newly formed structure retains the merits of graphene aerogel such as high specific surface area, good electronic conductivity, and porous structure. The electrochemical performance was investigated by a galvanostatic charge-discharge test (GDC) and a specific capacitance of 246.3 F g −1 was achieved, endowing it with great application potential as an supercapacitors electrode material. [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]

Li-rich Mn-based cathode materials are one kind of the promising potential candidates to electric vehicles powered by high-energy density lithium-ion batteries due to its much higher theoretical energy density. Unfortunately, the rapid capacity fading and voltage decay are the most critical factors affecting its practical application. Herein, Li 1 · 17 Na 0 · 02 Mn 0 · 54 Ni 0 · 13 Co 0 · 13 O 2 (PN-LMNCO) is prepared via surface phase structure controlling and ion doping through an architecture strategy of surface lithium deficiency. It is found that the existence of lithium deficiencies can induce surface phase transformation, and thus resulting in an in-situ spinel surface conversion film, which can restrain the structure degradation during subsequent charge/discharge process. In addition, because of the larger ion radius than Li+, Na+ doping can effectively increase the spacing between Li layers, and thus improve the rate capacity. Accordingly, the as-prepared sample displays as a significantly higher initial coulombic efficiency (91.2%). After 200 cycles at 1 C, the PN-LMNCO can retain 94.7% discharge specific capacity. Furthermore, PN-LMNCO can still show a good discharge capacity of 214 mA h g−1 even at a high current rate of 5 C. Therefore, this work can preferably meet the need of the development of electric vehicle for high-energy density Lithium-ion battery. • Lithium deficiencies induce the in-situ spinel surface conversion film. • The interfacial reaction has been inhibited. • Na doping improves the diffusion kinetics of lithium ions. • There are any redundant synthesis steps and the cost be reduced. [ABSTRACT FROM AUTHOR]

The structure design strategy for LRO based on the reversible anionic redox and spinel-layered coherent structure is propitious to maintaining high specific capacity and improving the reversible anionic redox and stable cyclic performance of LRO. [Display omitted] • LRO cathode with reversible anionic redox and spinel-layered coherent structure is designed. • The specific capacity and initial Coulombic efficiency are enhanced by the introduction of S-anions. • Stable interface structure and enhanced electrochemical kinetics are realized by the spinel-layered coherent structure. • Improved specific capacity and excellent cyclic stability are revealed in the modified LRO. Initiating effective strategies to improve the reversibility of anionic redox and structural stabilization is crucial to the development and industrial application of Li-rich cathode materials (LRO), which are regarded as the preferred option of the cathode materials for the next-generation lithium-ion battery with high energy density. To remit the unexpected behavior of structural destruction and capacity attenuation, this paper proposes a strategy for maintaining high specific capacity and improving the reversible anionic redox and stable cyclic performance of LRO by introducing the spinel-layered coherent structure and S-anions. Proved by the ex-situ X-ray photoelectron spectroscopy, S-anions can regulate the anionic redox reversibility and thus enhance the reversible discharge capacity and initial Coulombic efficiency. Moreover, the structural stability is greatly improved by the introduction of spinel-layered coherent structure and S-anions in LRO, which has been confirmed by abundant structural characterizations. Besides, the results reveal that the optimized material exhibits a high reversible discharge capacity of 289.52 mAh/g and good cyclic performance with a retention rate of 88.21% after 200 cycles. Evidently, the structure design strategy for LRO based on the reversible anionic redox and spinel-layered coherent structure is a significant exploration, which will bring a new clew for the design of the cathode materials with high-energy–density and excellent electrochemical performance. [ABSTRACT FROM AUTHOR]

[Display omitted] • A facile strategy is developed to synthesize multiphase Fe-based catalyst. • The Fe/Fe 3 C/FeN 0.0324 @N-GC exhibits excellent pH-universal ORR activity. • It possesses better battery performance than Pt/C in alkaline and neutral media. • The activity is attributed to the synergy among Fe-based sites dominated by Fe 3 C. • The active of Fe-based sites is probed by DFT calculation: Fe 3 C > Fe > FeN 0.0324. Iron-based nitrogen-doped carbonaceous materials are currently the most promising alternative towards oxygen reduction reaction (ORR) electrocatalysts due to the highly efficient active sites of single-atom Fe-N X coordination. However, the fact that iron-containing nanocrystals are easier to form during pyrolysis without additional tuning while providing activity comparable to single-atom sites cannot be ignored. Herein, we propose a facile and efficient strategy to synthesize iron nanocrystals sites with multiphase embedded in porous nitrogen-doped graphitized carbon (Fe/Fe 3 C/FeN 0.0324 @N-GC-X, X = 700, 850, and 1000). Based on highly active Fe 3 C@N-GC sites and the synergistic effect of Fe 3 C-dominated multiple iron-based, Fe/Fe 3 C/FeN 0.0324 @N-GC-850 exhibits excellent electrocatalytic activity towards ORR in pH-universal media. Specifically, it exhibits satisfactory onset potential (E onset), half-wave potential (E 1/2) and stability, and thus surpassing the benchmark Pt/C in both alkaline and neutral media as well as approaching Pt/C in acidic media. When employed as an air cathode in zinc-air batteries (ZABs), it also presents higher open-circuit voltage (OCV), discharge voltage plateaus, capacity, and peak power density compared with Pt/C. Density functional theory (DFT) calculations demonstrate that Fe 3 C (2 2 0)/N-GC has lower activation energy during ORR process and the overpotential generated by Fe 3 C/N-GC (0.7 V) is obviously less than one of Fe/N-GC (1.37 V) and FeN 0.0324 /N-GC (1.69 V). [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]

Closely wrapped Si@graphene structure with improved contacting interface were synthesized by a facile compression method. The improved contacting interface have greatly enhanced the positive effect of graphene sheets on restraining the volume change of Si nanoparticles and improving the electronic conductivity. The obtained composite sample shows significantly improved electrochemical performance as anode material for Li-ion batteries. [Display omitted] • Closely wrapped Si@graphene structure with improved contact interface was synthesized by a facile compression method. • The improved contact interface has enhanced the effect of graphene on restraining the volume change of Si nanoparticles. • The composite sample shows significantly improved cycling stability and rate performance. Despite their extremely high capacity (4200 mA h g−1), the practical application of silicon anodes is still frustrated by their poor cycling performance, resulting from severe volume changes and pulverization of the electrode material. Introducing graphene in silicon is an ideal approach for addressing these issues. Nevertheless, the large size difference between Si and graphene makes high-quality contact difficult to realize, which severely harms the electrochemical performance of Si/graphene composites. Herein, a unique Si@graphene layer structure (p-Si@GN) with an improved contact interface is fabricated by a facile high-pressure method, in which the surfaces of silicon particles are closely covered by graphene layers, restraining the volume changes from multiple angles. The superior structure of the layered p-Si@GN composite exhibits multiple desired features for high-performance Si-based anodes, such as high Li+ storage capacity resulting from high-capacity Si nanoparticles, outstanding electron conductivity due to the formation of a continuous graphene conductive network, and excellent structural stability due to the enhanced protective function of graphene layers with an improved contact interface. Due to these advantages, the p-Si@GN 40 anode, prepared under 40 MPa pressure, exhibits a significantly improved capacity of 2096.9 mA h g−1 at a current density of 300 mA g−1, an enhanced rate capability of 706.4 mA h g−1 at 3000 mA g−1, and superior cycling performance with a high capacity retention of 82.6 % after 150 cycles. [ABSTRACT FROM AUTHOR]

• Construct carbon protective shell to alleviate huge volume changes of Si. • Robust carbon framework can effectively maintains the structure integrity. • Carbon buffer layer can offer rich e-/ion channels to improve reaction kinetics. • The SCM electrode exhibited excellent electrochemical performance. Si-based anodes have revealed the potential as the next generation of lithium ion battery anode material, whereas the poor conductivity and huge volume changes during (de)lithiation process of silicon still limit their practical application. Herein, the Si/nitrogen doped carbon layer/carbon framework microspheres (SCM) are designed by nano-Si via electro-spray technology as anodes for lithium ion batteries. It has been found that the SCM consists of individual carbon-coated nano-Si primary particles linked by PAN framework, in which the carbon buffer layer can further absorb the stress of volume changes during charge/discharge process, and the carbon framework carbon framework not only provides fast diffusion path of electron, but also effectively reduces the consumption of electrolyte. Therefore, the initial columbic efficiency (ICE) of SCM anode can reach as high as 72%, and the SCM anode also shows a high specific capacity of 1192 mAh g−1 at 0.2 A g−1 and keeps a reversible capacity of 746 mAh g−1 after 200 cycles, demonstrating the as-designed SCM possesses an high ICE and a good electrochemical performance. This strategy provides a significant inspiration for fabricating high-performance Si/C anode materials of lithium-ion battery. [ABSTRACT FROM AUTHOR]

• Construct Mn 3 O 4 protective shell to alleviate Jahn-Teller distortion. • Oxygen vacancy can effectively restrain the release of oxygen. • The designed LRNMO@Mn 3 O 4 cathode has higher electron/ion conductivity. • The Mn 3 O 4 -coated electrode exhibited excellent cycle stability. Herein, we put forward a feasible interfacial modification strategy in virtue of Mn 3 O 4 surface coating to construct protective shell and alleviate Jahn-Teller distortion during the charge/discharge process. It has been found that the increase of the oxygen vacancy on the surface of Li 1.2 Ni 0.27 Mn 0.54 O 2 of (LRNMO) after Mn 3 O 4 protective layer modification can effectively restrain the release of oxygen and enhancing rate capability, and thus improving its comprehensive electrochemical performances. In particular, the initial coulombic efficiency of the optimized LRNMO-1 electrode is improved from 72.3% to 84.3%. The capacity retention rate is up to 95.6% at 250 mA g−1 (1C) after 200 cycles. In addition, the LRNMO-1 electrode also has a good capacity retention rate (96.4% after 100 cycles) at a high current density of 5C. Moreover, the designed LRNMO@Mn 3 O 4 cathode exhibits higher ionic conductivity and better interface stability. As a result, this work offers a practicable and valuable exploration for the development and industrialization of Co-free Li-rich Mn-based cathode materials with high energy density. [ABSTRACT FROM AUTHOR]

The shortage of lithium resource has become a serious problem due to the ever-increasing demands for lithium-ions batteries (LIBs) in the fields of electric vehicle and grid energy storage. It is imperative to recycle LIBs whether from the perspective of value recovery or environmental protection. Herein, a new method for recovering FePO 4 and Li 2 CO 3 from spent LiFePO 4 cathode materials is proposed. LiFePO 4 was synthesized by carbothermal reduction based on the recovered FePO 4 and Li 2 CO 3. It is well known that LiFePO 4 has poor electronic conductivity and ionic conductivity. In order to improve its electrochemical performance, accelerate the transport speed of lithium ions in the material, and improve its conductivity, a series of samples with different carbon coating contents are prepared. The physicochemical and electrochemical performances are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and electrochemical techniques. The results show that when the carbon is 12 wt% of the LiFePO 4 composite total weight, the sample (LFP-G12) has better electrochemical performance. LFP-G12 has a high initial discharge specific capacity of 146.89 mAh g−1 at 1 C with 97.9% of the initial capacity was retained after 200 cycles. Thus, this paper offers a brand-new way for recycling and directly using the spent LiFePO 4 to prepare LiFePO 4 cathode material. [Display omitted] • Li 2 CO 3 and FePO 4 were recovered from LiFePO 4 by oxidation leaching. • LiFePO 4 was prepared by using raw materials recovered from spent LiFePO 4 battery.. • Carbon coating improves electron/ion conductivity. • LiFePO 4 with carbon coating were obtained by adjusting the dosage of glucose. • The sample of LFP-G12 has good electrochemical performance. [ABSTRACT FROM AUTHOR]

• Co-free lithium-rich material was prepared by simple oxalate co-precipitation way. • The nano-micron combined structure was favorable to the infiltration of electrolyte. • The anions regulated the valence of surface transition metal ions. • The F-doped electrode exhibited excellent cycle stability. Co-free cathode materials are gradually attracted wide attention due to the low budget and environmental friendliness, but their application is still prevented by the poor rate performance and cyclic stability. Herein, the Co-free lithium-rich cathode materials (Li 1.2 Ni 0.2 Mn 0.6 O 2 , LRNMO) with a nano-micron combined morphology is prepared by a simple oxalate co-precipitation route and further modified by an anion doping strategy. It has been found that the F− anion doping can increase the content of Mn4+ in LRNMO, reduce the influence of the Jahn-Teller effect, and further impede the transition from layered phase to spinel phase. As a result, the as-obtained Li 1.2 Ni 0.2 Mn 0.6 O 2-x F x (x = 0.04, named as F4-LRNMO) shows an optimal electrochemical performance, for instance, high discharge capacity (243 mAh g−1) with a satisfactory initial coulombic efficiency of 84.37% at 0.1C. Meanwhile, the F4-LRNMO sample also can display high capacity retention of 92.2% after 200 cycles at 1C, and a remarkably high discharge capacity of 151 mAh g−1 with capacity retention of 95.4% after 100 cycles even at high rate of 5C. In consequence, this work can not only ameliorate the defects of poor stability and low initial coulomb efficiency, but also offer a meaningful exploration for the development of Co-free lithium-rich cathode materials with high capacity and high performance-price ratio. [ABSTRACT FROM AUTHOR]

[Display omitted] • Polar and conductive titanium carbide is introduced for redox regulation. • Lithium sulfide plays as sulfur source in this study. • Sulfur redox and lithium sulfide precipitation are remarkably promoted. • The electrochemical characteristics of as-prepared batteries are boosted. The lithium-sulfur batteries (LSBs) have attracted more and more attention in recent years owing to its high theoretical energy density, abundant sulfur source and relatively low cost. However, the serious polysulfides shuttle and sluggish sulfur redox kinetics hinder the development and commercial application of high-performance lithium-sulfur batteries. In this paper, the titanium carbide (TiC)-decorated carbon matrix is considered as the mediator, anchor and electrocatalyst for polysulfides redox reaction. It has been proved that the conductive and polar titanium carbide can not only chemisorbs lithium polysulfides via titanium-sulfur (Ti-S) coordination, but also optimize the lithium sulfide (Li 2 S) nucleation/precipitation mechanism for better redox reaction. Especially, the graphene oxide and carbon nanotube matrix (GO-CNT) in this case can act as both host for Li 2 S loading and TiC precipitation. Accordingly, the as-fabricated lithium sulfide-graphene oxide–carbon nanotube-titanium carbide (LS-GO-CNT-TiC) cathode delivers the high initial discharge capacity of 956 mAh g−1 at 0.1C and good rate capability of 508 mAh g−1 at 2C. These results consequently manifest that the conductive and polar matrix of LS-GO-CNT-TiC can perform as a promising cathode of the high performance LSBs. [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]

[Display omitted] • An ultralow-potential H 2 Ti 3 O 7 ·xH 2 O anode is first introduced for zinc-ion batteries. • The storage mechanism of H+ and Zn2+ co-insertion is demonstrated on the H 2 Ti 3 O 7 ·xH 2 O anode. • The H 2 Ti 3 O 7 ·xH 2 O anode features excellent electrochemical performance. • The assembled Zn x MnO 2 //H 2 Ti 3 O 7 ·xH 2 O full battery exhibits the high output voltage. Developing the alternative anode materials that can completely resolve the dendrite concern of Zn metal anodes are desirable for reliable aqueous zinc-ion batteries. However, the sub-optimal charging potentials of reported anodes inevitably cause the discounted output voltage and energy density on a zinc-ion full battery. Herein, it is firstly demonstrated that the hydrated titanic acid (H 2 Ti 3 O 7 ·xH 2 O) can be applied as an ultralow-potential anode for the aqueous zinc-ion full battery. The depressed potential (0.2 V vs. Zn2+/Zn) of the H 2 Ti 3 O 7 ·xH 2 O compared to that of reported candidates could significantly enhance the operating voltage level of the zinc-ion full battery. Furthermore, the comprehensive analyses demonstrate that the expanded lattice spacings and interlayer crystal water stimulate Zn2+ along with H+ to jointly insert and extract on the H 2 Ti 3 O 7 ·xH 2 O anode. The low-potential H 2 Ti 3 O 7 ·xH 2 O anode exhibits an impressive cycling performance and coulombic efficiency by virtue of the assistance from interlayer crystal water. The assembled Zn x MnO 2 //H 2 Ti 3 O 7 ·xH 2 O zinc-ion full battery delivers the decent electrochemical performance, especially a high output voltage of over 1 V. This low-potential, high-stable H 2 Ti 3 O 7 ·xH 2 O anode reveals the exceptional potential for aqueous zinc-ion full batteries. [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]

We present a separator modification strategy to suppress polysulfide shuttle and accelerate polysulfide conversion through transition metal coordinated g-C 3 N 4 with crystalline carbons. The Li-S batteries with Ni-C 3 N 4 /C-modified separator manifest improved electrochemical performance even at high sulfur loading and lean electrolyte condition, due to catalytic effect. • Transition metal coordinated g-C 3 N 4 with crystalline carbons is prepared. • Hybrid nanosheets efficiently prevent polysulfide diffusion by absorption effect. • This structure endows the lean-electrolyte Li-S batteries higher capacity. • Cell with Ni-C 3 N 4 /C-modified separator exhibits the best electrochemical performances. Lithium-sulfur batteries have been regarded as promising energy storage candidates because of their high energy density and low cost. However, the low electrical conductivity of sulfur, infamous polysulfides shuttle and slow redox kinetics result in fast capacity fade and poor rate capabilities. To solve these barriers, herein a modification strategy of functional separator is presented by coating transition metal coordinated graphitic carbon nitride (g-C 3 N 4) with crystalline carbons (M-C 3 N 4 /C) on the surface of a commercial separator. The coating layer exhibits both satisfactory interception ability for polysulfides shuttle and fast polysulfides conversion ability. It has been found that the uniformly distributed transition metal on g-C 3 N 4 /C acts as an active center to regulate polysulfides behavior via strong chemisorption capability and high catalytic activity towards polysulfide conversion, while the transition metal-interface guarantees the rapid electron transfer, which can consequently facilitate the utilization of active sulfur species. Notably, after considerable assessments from density functional theory calculations, spectroscopy and electrochemical performances, it can be concluded that the Ni-C 3 N 4 /C can strongly bind polysulfides and expedite polysulfides conversion kinetics as well as promote electrons/ion transfer. As a result, the lithium-sulfur batteries with Ni-C 3 N 4 /C-modified separator can deliver 999 mAh g−1 at 0.5 A g−1 with high capacity retention of 89.4% after 300 cycles. Even at a great sulfur loading of 4.6 mg cm−2 and a low electrolyte/sulfur ratio of 6 µL mg−1, a large initial capacity of 724.6 mAh g−1 is still obtained at 1.0 A g−1. The separator reported in this work initiates the exploration of transition metals coordination as dynamic regulators of high-performance lithium-sulfur batteries and also reveals an understanding of the catalytic reactions. [ABSTRACT FROM AUTHOR]