Search

Chemical manipulation of surface functional groups on two‐dimensional transition metal carbides and/or nitrides (MXenes) provides a wide range of design and application prospects. However, achieving rapid targeted modification of surface groups remains a significant challenge. Herein, we propose a general strategy to swiftly shear and customize surface groups on Ti3C2Tx−MXene via the flash Joule heating (FJH) reaction within 1 s. Successfully, MXenes with 9 target terminations, including VII A (F, Cl, Br, or I), VI A (O, S, or Se), and V A (N or P), either single or multiple, are synthesized, with a surface content of up to about 76 %. The impact of these terminations is systematically analyzed on electrochemical performance, demonstrating that VI A and V A terminations have higher electrochemical activity than VII A. Particularly, N‐, S‐, and O‐terminated MXenes exhibit enhanced specific capacities and undecayed cycling performance. These findings offer valuable insights for the surface engineering design and performance optimization of functional materials. [ABSTRACT FROM AUTHOR]

Aqueous zinc ion batteries (AZIBs) have stimulated extensive attention due to their environmental friendliness and low cost. Unfortunately, the inevitable dendrite growth and corrosion on the zinc (Zn) anode severely hinder the practical application of AZIBs. Herein, an amino acid containing an imidazole group is introduced as an effective additive to address these issues. The dynamic conversion of amino acid and protonated amino acid creates a pH buffer function that regulates solution pH in real time, inhibits hydrogen evolution reaction (HER), and eliminates notorious by‐products. In addition, the protonated amino acid is preferentially adsorbed on the Zn anode, preventing contact of the active water with the Zn surface and promoting homogeneous Zn deposition. Thus, the amino acid‐based electrolyte promotes dendrite free plating/stripping with a Coulombic efficiency up to 99.67% and cycle lifetime of 2600 h. In particular, a depth of discharge of up to 87% can be achieved with an ultra‐high areal capacity of 24 mAh cm−2. The developed Zn||CVO full cell also exhibits better electrochemical performance than that without additives. This work provides an effective and convenient approach for safe and efficient Zn‐ion batteries. [ABSTRACT FROM AUTHOR]

The lack of high‐performance electrodes is a key factor restricting the development of sodium‐ion batteries (SIBs), and usually a certain type of electrode material alone often fails to combine the merits of high capacity and good conductivity. Herein, nitrogen‐doped carbon (NC) was used as a multifunctional bridge to uniformly compound high‐capacity MoS2 nanoparticles with highly conductive Ti3C2Tx nanosheets to form Ti3C2Tx@MoS2/NC composite with flower‐like architecture. Ultrafine MoS2 nanoparticles were uniformly anchored on Ti3C2Tx nanosheets to form nanosheets primary building blocks with a sandwich‐like architecture, which not only shortens the ion transfer distance but also enlarges the layer spacing of Ti3C2Tx favoring the storage of more sodium ions as well as their transport capacity. Moreover, the flower‐like structures with abundant edges can provide an ample active sites and high pseudocapacitance behavior. As a result, flower‐like Ti3C2Tx@MoS2/NC displays a high electrochemical properties with an excellent cycling stability over 2000 cycles (81.4 % capacity retention) and preeminent rate capacity of 383 mAh g−1 at 30 A g−1. Furthermore, Ti3C2Tx@MoS2/NC‖Na3V2(PO4)3 full cell displays a capacity of 59 mAh g−1 at 0.4 A g−1 after 180 cycles. This work displays a high‐performance anode composite for SIBs and provides insight into the preparation of other composites. [ABSTRACT FROM AUTHOR]

Aqueous Mg ion batteries (AMIBs) show great potential in energy storage for their advantages of high capacity, abundant resource, and environmental friendliness. However, the development of AMIBs is limited due to the scarcity of suitable anode materials. In this study, a new polymer anode material (PNTAQ) with flower‐like nanosheet structure is synthesized for aqueous Mg‐Na hybrid‐ion battery (AMNHIB). PNTAQ possess carbonyl functional groups which can be oxidized and reduced reversibly in aqueous solution containing alkaline metal ions. PNTAQ displays a discharge specific capacity of 245 mAh g−1 at 50 mA g−1 in 1 M MgCl2 + 0.5 M NaCl electrolyte, which is much higher than that in single 1 M MgCl2 or 0.5 M NaCl electrolyte. Even cycling at 1000 mA g−1 for 1000 times, the capacity retention can still maintain at 87.2%. A full Mg‐Na hybrid‐ion cell is assembled by employing β‐MnO2 as cathode and PNTAQ as anode material, it exhibits a specific capacity of 91.6 mAh g−1 at 100 mA g−1. The polymer electrode material well maintains its framework structure during the discharge/charge cycling process of the hybrid‐ion battery. [ABSTRACT FROM AUTHOR]

Aqueous Mg‐ion batteries (MIBs) lack reliable anode materials. This study concerns the design and synthesis of a new anode material – a π‐conjugate of 3D‐poly(3,4,9,10‐perylenetracarboxylic diimide‐1,3,5‐triazine‐2,4,6‐triamine) [3D‐P(PDI‐T)] – for aqueous MIBs. The increased aromatic structure inhibits solubility in aqueous electrolytes, enhancing its structural stability. The 3D‐P(PDI‐T) anode exhibits several notable characteristics, including an extremely high rate capacity of 358 mAh g−1 at 0.05 A g−1, A 3D‐P(PDI‐T)‖Mg2MnO4 full cell exhibits a reversible capacity of 148 mAh g−1 and a long cycle life of 5000 cycles at 0.5 A g−1. The charge storage mechanism reveals a synergistic interaction of Mg2+ and H+ cations with C−N/C=O groups. The assembled 3D‐P(PDI‐T)‖Mg2MnO4 full cell exhibits a capacity retention of around 95 % after 5000 cycles at 0.5 A g−1. This 3D‐P(PDI‐T) anode sustained its framework structure during the charge–discharge cycling of Mg‐ion batteries. The reported results provide a strong basis for a cutting‐edge molecular engineering technique to afford improved organic materials that facilitate efficient charge‐storage behavior of aqueous Mg‐ion batteries. [ABSTRACT FROM AUTHOR]

The non-uniform plating–stripping behaviours of Li metal anodes hinder the application of Li metal batteries. Here, a stable 3D matrix is designed by coating a carbon skeleton with MXene, and the significant influence of the crystallographic texture of Li metal on electrochemical behaviour is investigated. The results demonstrate that the 3D MXene/carbon skeleton can effectively induce the evolution of advantageous Li(110) facets with a dendrite-free anode interface. Consequently, the modified Li metal anodes deliver stable plating–stripping behaviours. [ABSTRACT FROM AUTHOR]

Sodium‐ion hybrid capacitors (SIHCs) are considered a prospective alternative to lithium‐ion batteries (LIBs) since there are rich and available sodium reserves. Here, nitrogen‐doped carbon tubes (N‐MJ) derived from metaplexis japonica fluff are prepared by using a facile method of etching and peeling the fluff with urea to prepare a Na+ storage anode. With prominent traits in terms of structure and a high nitrogen content (11.08 %), N‐MJ exhibits exceptional Na+ storage performance with a high reversible capacity (390.9 mAh g−1 at 50 mA g−1) and excellent long‐term circulation (208.1 mAh g−1 after 2650 cycles at 1 A g−1). Systemic kinetic analysis manifests that the extraordinary performance is responsible for the large‐scale capacitance control. Furthermore, the SIHCs assembled by using N‐MJ and activated carbon (AC) presents a maximum energy density of 111.4 Wh kg−1 (at 445.8 W kg−1) and power density of 2455.2 W kg−1 (at 34.1 Wh kg−1). Notably, the developed SIHCs maintain a 100 % capacity retention rate at 1 A g−1 after 5000 cycles. Overall, our work not only provides a good choice for storage Na+ anode materials, but also supplies a feasible method for the recycling of waste biomass. [ABSTRACT FROM AUTHOR]

Potassium‐ion hybrid capacitors have attracted increasing attention due to good energy density, high power density, and low cost. Ti3C2Tx‐MXene is considered as a promising anode material for K ion storage. However, undesirable stacking issues decrease its exposed area and breeds sluggish K ion transport. Herein, a facile spray‐lyophilization strategy is proposed to construct stacking‐resistant Ti3C2Tx with 3D structures. As‐prepared Ti3C2Tx hollow spheres/tubes present stack resistance, a large specific surface area, and a short ion diffusion pathway. When serving as an anode material, it shows enhanced capacity and thickness‐independent rate performance compared to 2D Ti3C2Tx. After 10 000 cycles, a specific capacity of 122 mAh g−1 is obtained at 1 A g−1. Systematic kinetics analyses demonstrate the significance of concentration polarization on the electrode's rate ability. Furthermore, a 3D Ti3C2Tx‖hierarchical porous activated carbon (HPAC) K‐ion hybrid capacitor is assembled and displays remarkable energy and power densities with energy retention of 100% after 10 000 cycles at 1 A g−1. Following this strategy, other 3D structures from nanosheets can also be obtained, such as 3D Ti3C2Tx microtubes and graphene oxide nanoscrolls. This study provides a viable approach to solve the stacking issues of 2D nanosheets to promote the application of 2D materials. [ABSTRACT FROM AUTHOR]

Aqueous batteries have attracted increasing and extensive attention, owing to their high safety, low cost, and low toxicity. These factors have become increasingly important, given the current focus on the rapid development of green energy technologies. In particular, multivalent‐ion batteries are emerging as alternatives to lithium‐ion batteries. Unfortunately, magnesium and aluminum ions have high polarization strengths that are unfavorable for electrode materials. In contrast, calcium‐ion batteries successfully avoid the problem of high polarization. Herein, an aqueous calcium‐ion battery (CIBs) based on mesoporous silica SBA‐15 with a two‐dimensional hexagonal through‐hole structure is reported. The poly(3,4,9,10‐perylentetracarboxylic diimide) (PPTCDI) organic material supported on SBA‐15 is used as the anode and displays a capacity of 201 mAh g−1, with a stable cycling performance of 95 % capacity retention after 1500 cycles. SBA‐15@PPTCDI‖Ca2MnO4 aqueous CIBs demonstrate a high energy density of 130.6 Wh kg−1 in the cell voltage range from 0.0 to 1.8 V, with a high capacity and excellent cycling stability. As the anode material, SBA‐15@PPTCDI shows special bonding of redox electrons that leads to its highly stable performance, which paves the way for addressing the shortcomings of traditional organic electrode materials. The localization and delocalization of the redox electron offers additional voltage stability, which is another important advantage for practical applications. This study highlights the potential of organic electrode materials for applications in aqueous multivalent‐metal‐ion batteries. [ABSTRACT FROM AUTHOR]

A fast one‐step arc discharge exfoliation method is employed to synthesize Si/graphene composites by using a graphite rod filled with a mixture of Si powder and urea as a cathode. During the arc discharge process, the use of urea allows both the introduction of nitrogen atoms into the graphene and the uniform sealing of Si nanoparticles between the thin graphene sheets to occur simultaneously. The resulting N‐doped graphene nanosheets embedded with Si (Si@NG) can act as an electrode material for lithium‐ion batteries and delivers the reversible capacity of 1030 mAh g−1 with a current density of 200 mA g−1 over 100 cycles along with an outstanding coulombic efficiency of 96.84 %. The remarkable electrochemical rate capability performance can be owed to the multiple role of NG, which not only serves as a three‐dimensional conductive support, but also effectively limits the volume variation of Si nanoparticles. The approach proposed here is expected to be extended to the preparation of other alloy anode/graphene hybrids for lithium ion batteries. [ABSTRACT FROM AUTHOR]

Highlights: A freestanding MXene-derived defect-rich TiO2@reduced graphene oxides (M-TiO2@rGO) foam electrode was fabricated. M-TiO2@rGO presents fast Na+ storage kinetics due to capacitive contribution. M-TiO2@rGO foam electrode displays a capacity retention of 90.7% after 5000 cycles. Sodium ion batteries and capacitors have demonstrated their potential applications for next-generation low-cost energy storage devices. These devices's rate ability is determined by the fast sodium ion storage behavior in electrode materials. Herein, a defective TiO2@reduced graphene oxide (M-TiO2@rGO) self-supporting foam electrode is constructed via a facile MXene decomposition and graphene oxide self-assembling process. The employment of the MXene parent phase exhibits distinctive advantages, enabling defect engineering, nanoengineering, and fluorine-doped metal oxides. As a result, the M-TiO2@rGO electrode shows a pseudocapacitance-dominated hybrid sodium storage mechanism. The pseudocapacitance-dominated process leads to high capacity, remarkable rate ability, and superior cycling performance. Significantly, an M-TiO2@rGO//Na3V2(PO4)3 sodium full cell and an M-TiO2@rGO//HPAC sodium ion capacitor are fabricated to demonstrate the promising application of M-TiO2@rGO. The sodium ion battery presents a capacity of 177.1 mAh g−1 at 500 mA g−1 and capacity retention of 74% after 200 cycles. The sodium ion capacitor delivers a maximum energy density of 101.2 Wh kg−1 and a maximum power density of 10,103.7 W kg−1. At 1.0 A g−1, it displays an energy retention of 84.7% after 10,000 cycles. [ABSTRACT FROM AUTHOR]

The need for safe, cost-effective aqueous magnesium ion batteries has led to high electrochemical performance designs of materials and structures to meet strict requirements. A composite of manganese dioxide and carbon molecular sieves (δ -MnO 2 @CMS) with a core-shell structure is used as the cathode in the aqueous magnesium ion battery, which not only solves the inherent deficiencies of low conductivity from manganese dioxide but also maximizes its specific capacities via a hierarchical structure. In addition, the anode material, nanowire VO 2 (formed via a solvothermal reaction) is rarely investigated in this system. Interestingly, this material can form new electrodes with more stable structures after the first charged process and avoids the formation of MgO, thereby providing insertion/extraction of magnesium ions into/from the host anode material. An aqueous rechargeable magnesium ion battery can be successfully assembled using the two electrodes designed above. This device shows high rate properties and delivers reversible capacities of 112.2, 94.6, 78.7, 69.5, and 59.1 mAh g−1 at current densities of 50, 100, 200, 300, and 500 mA g−1. Image 1 • δ -MnO 2 @CMS with core-shell structure is synthesized by hydrothermal method. • The nanowire VO 2 as anode is obtained by simple one-step hydrothermal process. • The Mg2+ insertion/deinsertion mechanism of two electrodes is explored. • Assembled aqueous magnesium-ion battery exhibits excellent rate property. [ABSTRACT FROM AUTHOR]

The borohydride oxidation reaction (BOR) is the main reaction in the anode of direct borohydride fuel cells (DBFCs), which is also fundamental to highlight the advantages of DBFCs. However, the catalysis of BOR still faces many challenges. On the one hand, further breakthroughs in catalytic activity are sought to achieve high performance of the anode; on the other hand, the negative effects brought by the side reactions, including the bubble effect, loss of fuel utilization, poisoning of the catalyst, etc., are urgently needed to be mitigated. Essentially, the running of the anode is the catalysis of BOR, so the catalytic viewpoint is critical to solving the above problem. In this work, an updated review of the effects of electrode design and the modulation of the catalytic environment on the anode is provided. Specifically, the electrode design is reviewed mainly from the perspective of catalytic activity, selectivity, and protective strategies. Besides, the modulation of the catalytic environment is emphasized in the systematic configuration and reactant transfer engineering. This work is expected to provide an in-depth understanding of the catalysis of BOR and afford significant inspiration toward the design of the anode. In this work, an updated review of the effects of electrode design and the modulation of the catalytic environment on the anode of direct borohydride fuel cells is provided. [Display omitted] • Based on a catalytic perspective DBFC anodes were reviewed. • Engineering strategies for electrode design are summarized. • The effects of catalytic environmental on the anode are discussed. • Challenges and outlooks for the design of DBFC anodes are provided. [ABSTRACT FROM AUTHOR]

[Display omitted] MoS 2 is regarded as a hopeful anode candidate for sodium-ion batteries (SIBs) due to their various merits such as high specific capacity, abundant raw material reserves and low cost. However, their practical application is impeded by unsatisfied cycling ability due to the intense mechanical stress and unstable solid electrolyte interphase (SEI) during Na+ insertion/extraction process. Herein, spherical MoS 2 @polydopamine derived highly conductive N -doped carbon (NC) shell composites (MoS 2 @NC) are designed and synthesized to promote the cycling stability. The internal MoS 2 core is optimized and restructured from the original micron-sized block to the ultra-fine nanosheets during initial 100–200 cycles, which not only improves the utilization of electrode materials but also shortens the ion transport distance. The outer flexible NC shell effectively maintains the original spherical structure of the overall electrode material and prevents the occurrence of large-scale agglomeration, which is conducive to form a stable SEI layer. Therefore, the core–shell MoS 2 @NC electrode presents a remarkable cyclic stability and a capable rate performance. Under a high rate of 20 A g−1, the high capacity of 428 mAh g−1 can be acquired after over ultra-long 10,000 cycles without obvious capacity loss. Moreover, the MoS 2 @NC‖Na 3 V 2 (PO 4) 3 full-cell assembled by employing commercial Na 3 V 2 (PO 4) 3 cathode can achieve a high capacity retention of 91.4% after 250 cycles at 0.4 A g−1. This work reveals the promising prospect of MoS 2 -based materials as anode of SIBs, and also has some inspirations on the structural design for conversion-type electrode materials. [ABSTRACT FROM AUTHOR]

[Display omitted] Exploring capable and universal electrode materials could promote the development of alkalis (Li, Na, K) ion batteries. 2D MXene material is an ideal host for the alkalis (Li, Na, K) ion storage, but its electrochemical performance is limited by serious re-stacking and aggregation problems. Herein, we cleverly combined electrostatic self-assembly with gas-phase vulcanization method to successfully combine Ti 3 C 2 T x -MXene with ultra-long recyclability and high conductivity with MnS, which presents high specific capacity but poor conductivity. The as-prepared 3D hierarchical Ti 3 C 2 T x /MnS composites have an unique sandwich-like constituent units. The tiny MnS nanoparticles are restricted between the Ti 3 C 2 T x layers and play a key role in expanding the Ti 3 C 2 T x interlayer spacing. As a result, the 3D Ti 3 C 2 T x /MnS composites as the anode of LIBs exhibits a superior capacities of 826 and 634 mAh/g after 1000 and 3000 cycles at 0.5 and 1.0 A/g, respectively. More importantly, we reveal the reaction mechanism that the specific capacity first increases and then gradually stabilizes with the increase of charge and discharge cycle times when the as-prepared 3D Ti 3 C 2 T x /MnS was used as the anode of LIBs. In addition, we have also used this material in SIBs and PIBs and achieved remarkable electrochemical capability, with a specific capacity of 107 mAh/g after 2500 cycles at 0.5 A/g or 127 mAh/g after the 2000th cycle at 0.2 A/g, respectively. [ABSTRACT FROM AUTHOR]

[Display omitted] Rechargeable metal batteries such as non-aqueous Li metal batteries and aqueous Zn metal batteries have received increasing attention due to the benefits of the high-energy metal anode. However, the dendric growth on the metal anode extremely leads to restricted cycling performance and potential safety issues. Herein, the MXene-modified conductive framework (MCF) is designed and fabricated as a universal current collector of anode for non-aqueous Li metal batteries and aqueous Zn metal batteries to suppress the dendric Li and Zn growth. The MCF exhibits the merits of good lithiophilicity and zincophilicity, enables an easy Li/Zn nucleation process, and possesses high plating/stripping reversibility. After plating Li/Zn, MCF@Li and MCF@Zn realize a dendrite-free surface, facilitating Li/Zn plating/stripping kinetics. The MCF@Li and MCF@Zn symmetric cell shows a low overpotential of 13 mV at 1 mA cm−2 after 900 cycles and 64 mV at 5 mA cm−2 after 750 cycles (1 mAh cm−2), respectively. Furthermore, the non-aqueous MCF@Li||LiFePO 4 full cells and the aqueous MCF@Zn||active carbon capacitors are assembled and present stable cycling ability and improved rate performance with low polarization. This work provides a universal current collector strategy to meet the requirements of non-aqueous and aqueous metal anodes, which may inspire more designs for metal-based energy storage systems. [ABSTRACT FROM AUTHOR]

The highly porous electrode of a crisscrossed CoNi nanosheets array grown on reduced graphene oxide decorated Ni foam (CoNi/rGO@Ni foam) is fabricated through a facile dip and dry method followed by electroreduction and electrodeposition methods. The phase composition and morphology of the electrode are characterized by XRD, SEM, TEM, and EDS. In single electrode tests, CoNi/rGO@Ni foam electrode displays an excellent catalytic performance (330 mA cm−2 at 0.6 V) and stability towards urea electrooxidation when comparing to Ni foam and CoNi nanosheets modified Ni foam (CoNi@Ni foam) electrode. Besides, a low initial oxidation potential of urea electro-oxidation to 0.14 V is achieved on the CoNi/rGO@Ni foam electrode. The introducing of rGO to the electrode greatly reduced the reaction activation energy from 14.47 to 10.35 kJ mol−1. Besides, large active surface area (261.67 cm2) is also obtained from the electrode. The CoNi/rGO@Ni foam anode exhibits a maximum power density of 12.58 mW cm−2 in direct urea-hydrogen peroxide fuel cell tests. Excellent performance shows in single electrode tests and fuel cell tests suggest that addition of rGO to the electrode is an easy and feasible method to enhance the performance of the catalyst. • Highly porous electrode: crisscrossed nanosheets array grows on rGO modified Ni foam. • The influence of rGO on the catalytic performance of the electrode was researched. • Low initial oxidation potential towards urea electro-oxidation was obtained. • Achieved an excellent performance and stability when practical use in DUHPFC. [ABSTRACT FROM AUTHOR]

A three-dimensional free-standing hard carbon (FHC) electrode is synthesized by carbonizing the hemp haulm and employed as anode for sodium-ion batteries directly. A high current charging-discharging process is carried out to reconstruct surface structure of the FHC. Surface reconstructed FHC display a high capacity of 256 mAh/g and enhanced rate ability. With the formation of order surface structure, the plateau capacity increase and more sodium ions can insert into the FHC. This work demonstrates the importance of surface structure for sodium ion diffusion and storage and provide a new strategy to design high-performance anode materials. [ABSTRACT FROM AUTHOR]

An original three-dimensional self-supported reduced graphene oxide (rGO) foam is successfully prepared in this work. This novel support material, modified with Co nanosheets and Au nanoparticles, is employed as a high-performance catalyst for NaBH 4 electrooxidation under alkaline condition. The surface chemical component and morphology of the catalyst is characterized by X-ray diffraction pattern, X-ray photoelectron spectroscopy, scanning electron microscope. The synthesized electrode exhibits excellent performance (1.35 A cm−2 at 0 V) towards NaBH 4 electrooxidation. The unique structure of rGO foam caused a large electrochemical active surface area (EASA (Au) = 390 m2 g−1), low electrochemical impedance, as well as 55.4% utilization efficiency of NaBH 4. Also, catalytic kinetic parameters during the electrooxidation reaction of NaBH 4 in a low NaBH 4 concentration are investigated. Results indicate that oxidation of BH 4 − is a first-order reaction, and the exchanged number of electrons obtained at the CoAu/rGO foam electrode is 6.9. Finally, we practically apply it to a direct borohydride-hydrogen peroxide fuel cell (DBHPFC). This work suggests that the prepared rGO foam is an excellent current collector, and CoAu/rGO foam electrode is a promising anode catalyst to apply in DBHPFC. Image 1 [ABSTRACT FROM AUTHOR]

Catalytic performance and NaBH 4 utilization are two crucial concerns in the electrooxidation of NaBH 4. To improve the inherent properties of regular performance and low fuel utilization of the transition metal Co and Ni, an efficient anode catalyst of ultra-thin CoNi nanosheets modified novel 3D self-supported reduced graphene oxide foam is prepared in this work. The alkaline condition borohydride oxidation reaction on the prepared catalyst is investigated in a typical three-electrode system. The prepared catalyst shows a high performance due to the large electrochemical active surface area, low activation energy (8.29 kJ·mol−1), and the small electrochemical impedance it embraced. Linear scan voltammetry recorded in a low concentration of NaBH 4 suggests that borohydride oxidation is a first-order reaction on the prepared catalyst. Based on the unique structure of the catalyst, which is useful to capture the hydrogen and perform further oxidation of hydrogen, higher utilization of NaBH 4 achieved on the catalyst. Besides, the prepared anode catalyst applied to a direct borohydride-hydrogen peroxide fuel cell (DBHPFC). The results of polarization curve and power density curves, as well as stability research, all indicate that the as-prepared catalyst is a highly efficient anode material for application in DBHPFC. Unlabelled Image • Novel 3D self-supported rGO foam skeleton was prepared by a simple template method. • The catalytic activity of CoNi-NS/rGO foam is higher than CoNi-NS/Ni foam electrode. • Self-supported rGO foam matrix improved the utilization efficiency of NaBH4. • CoNi-NS/rGO foam anode catalyst exhibited highest power density of 140 mW·cm−2. [ABSTRACT FROM AUTHOR]

Graphical abstract Abstract Unique nanostructure, high electrical conductivity, satisfactory energy density, and extraordinary cycling stability are important evaluation criteria for high-efficient energy storage devices. Herein, Fe 3 O 4 nanospheres are successfully in situ decorated on graphene nanosheets through an environmentally benign and facile solvothermal procedure. When utilized as an electrode for supercapacitor, the graphene/Fe 3 O 4 nanocomposite exhibits a notably enhanced specific capacity (268 F·g−1 at 2 mV·s−1) and remarkable cycling performance with 98.9% capacity retention after 10,000 cycles. Furthermore, the fabricated graphene/MnO 2 //graphene/Fe 3 O 4 asymmetric supercapacitor device displays a desirable energy density (87.6 Wh·kg−1) and superior cycling stability (93.1% capacity retention after 10,000 cycles). [ABSTRACT FROM AUTHOR]

Aqueous magnesium ion battery as a new energy storage system is always explored due to excellent properties with high theoretical specific capacity, low-cost and safe aqueous electrolytes. However, the study on available material as anode in aqueous magnesium ion battery is very limited, which is the main reason that the kinetics of multivalent magnesium ions deinserted from the host material is very difficult. In this work, the nanoneedle FeVO 4 ·0.9H 2 O as available anode material is prepared and further modified by compositing with graphene. The FeVO 4 ·0.9H 2 O/Graphene composite exhibits the more excellent electrochemical performance, for example, the initial discharge capacity of FeVO 4 ·0.9H 2 O/Graphene electrode at the current density of 50 mAh g −1 in 1.0 mol L −1 MgSO 4 electrolyte is 183.8 mAh g −1 , but that of the FeVO 4 ·0.9H 2 O is 150.3 mAh g −1 . Therefore, the aqueous magnesium ion full battery is successfully assembled by FeVO 4 ·0.9H 2 O/Graphene as anode, 1.0 mol L −1 MgSO 4 as electrolyte and Mg-OMS-1 as cathode, which can obtain the discharge capacity of 53.1 mAh g −1 at a current density by calculate the total mass of two electrodes and the a high energy density of 58.5 Wh kg −1 . [ABSTRACT FROM AUTHOR]

[Display omitted] • A modified guar gum layer inhibits the Zn dendrites growth. • Breaking intramolecular hydrogen bonds prevents the HER. • RFH-GG@Zn symmetric cell demonstrates 2500 h cycling life. • AC||RFH-GG@Zn capacitors present cycling stability of 60,000 cycles. Zn-based energy storage devices such as Zn ion hybrid capacitor (ZICs) and Zn ion batteries (ZIBs) have attracted extensive attention due to the advantages of low cost, chemical stability, and high capacity of Zn metal anode. However, the Zn anode faces the difficulties of inevitable dendrite growth and hydrogen evolution reaction (HER) during cycling. Herein, we construct guar gum film, as artificial solid electrolyte interphase, on the Zn metal to suppress the dendrite grown and promote Zn deposition. Meanwhile, the Zn2+ desolvation process is enhanced by regulating the hydrogen bonding inside the film. As a result, the Zn anode coated with guar gum with rich free hydroxyl groups (RFH-GG@Zn) remains a low overpotential (45 mV) after an alternant plating/stripping process for more than 2,500 h. The application of RFH-GG@Zn promotes the cycling performance and rate ability of ZICs and ZIBs. This work aims to prepare high-performance Zn metal anodes by reducing intramolecular hydrogen bonding to enhance the protective effect of the coating on Zn anodes. [ABSTRACT FROM AUTHOR]

Scheme 1. Material synthesis. [Display omitted] • Characterization results confirmed the crystalline structure of the prepared samples. • FJH is more efficient in terms of time and energy than traditional heating. • HTC and FHC exhibited excellent performance as anode materials for LIBs and PIBs. • Graphitized coal can be a good alternative to graphite as anodes for LIBs and PIBs. Natural graphite, commonly used in energy storage applications such as the battery industry, is marked as a supply-risk material due to the elevated demand and limited resources. The synthetic graphite process is inefficient, so there is a highly required for alternative methods of making graphite as anode material. In this study, we report two efficient methods for catalytic graphitization of coal using high-temperature heating and flash Joule heating (FJH). Using both methods, the structure and morphology characterizations have demonstrated the successful structural conversion of coal from an amorphous structure into a crystalline structure. When the obtained graphitized coal samples via the high-temperature heating method (HTC) and via the FJH method (FHC) were used as anodes for lithium-ion batteries (LIBs) and potassium-ion batteries (PIBs), the HTC and FHC presented outstanding rate capability and remarkable stable cycling performance. The HTC and FHC anodes delivered initial charge capacities of 322.5 and 321.3 mAh·g−1, respectively, at a current density of 0.1C. for LIBs. When used as anodes in PIBs, the HTC and FHC delivered initial charge capacities of 265.4 and 262.2 mAh·g−1 at 0.1C current density. These results make the HTC and FHC promising materials for developing energy storage applications. Therefore, this work exploited the low price of coal and its abundant reserves, combined with the FJH technique, which is an effective method for saving energy and time, to produce high-quality graphitized coal materials, which can make this process green and economically attractive. [ABSTRACT FROM AUTHOR]

Organic polymer materials attract lots of attention as promising anode materials for lithium ion batteries (LIBs) due to the superior lithium ion storage capability and low cost. However, the inherent insulativity of the polymer anodes results in the unsatisfactory electrochemical performance. Herein, we design and construct a hierarchical flowers-like polyaniline-coated (PANI) pyromellitic dianhydride-based polyimide (PPI) composite (PANI-PPI-9). Benefiting from the core-shell structure, the PPI presents an improved electrochemical performance, especially the remarkable cycling life (503 mAh g−1 at 1.5 A g−1 after 2400 cycles). Ex-situ characterizations and kinetics analyses also verify that the PANI shell serves as the electronic transport highway without obstructing the Li storage of PPI. This work highlights the potential application of the multifarious polymer-based composite electrodes for the lithium ion batteries. • The structure construct strategy to design and prepare the PANI-coated PPI micron flowers. • Aromatic rings in the polyimide provide a large number of lithium storage sites. • The PANI-PPI-9 exhibits improved long-cycling and rate performance. [ABSTRACT FROM AUTHOR]

[Display omitted] • SnS x /N-rGO-30 with rich heterostructures was prepared by a hydrothermal route. • Built-in electric field greatly accelerates the charge transfer and ion diffusion. • SnS x /N-rGO-30 shows high Li+ storage capacity of 1273 mAh g−1 at 0.1 A g−1. • SnS x /N-rGO-30 shows high Na+ storage capacity of 640 mAh g−1 at 0.1 A g−1. Metal sulfides have been broadly used as potential candidates in lithium-ion and sodium-ion batteries. However, they usually undergo huge volume expansion and shrinkage, inferior electronic conductivity and sluggish redox reaction kinetics. Construction of heterostructure turns out to be a successful route to accelerate the charge transfer kinetics. Herein, ultrafine SnS x nanoparticles (∼5 nm) with abundant heterostructure are anchored on N-doped graphene through a hydrothermal approach. The rich heterostructures and the interfacial effect induced by built-in electric field significantly accelerate the charge transport and ion diffusion. The SnS x /N-rGO-30 nanocomposite displays large discharge capacity of 1273 mAh g−1 at 0.1 A g−1, superior rate ability (594 mAh g−1 even at 10 A g−1) as well as excellent cycling performance as anodes for Li-ion batteries. As for sodium-ion storage, the SnS x /N-rGO-30 nanocomposite exhibits high reversible capacity of 640 mAh g−1 at 0.1 A g−1 and high rate capability of 225 mAh g−1 at 10 A g−1. [ABSTRACT FROM AUTHOR]

• Cable-like PI@CNTs is designed and prepared via an in-situ polymerization approach. • The PI@CNTs anode exhibits far better long-term cycling performance than pure PI. • The structure of PI@CNTs facilitates Li ion diffusion and electron transportation. Polyimide (PI) with C = O groups and C 6 rings is considered as a promising anode material for lithium ion batteries. However, the potential application of PI is extremely hindered by its inherent properties with unsatisfied lithium ions diffusion and electron conductivity. Herein, the PI nanoflakes are grown on the carbon nanotubes (CNTs) to construct a cable-like structure (PI@CNTs) via an in-situ polymerization approach. The dispersed PI nanoflakes provide shorter lithium ion transmission distance and the CNTs substrate promotes electron transportation, leading to enhanced electrochemical performance. When served as anode material, PI@CNTs exhibits a specific capacity of 493 mAh g−1 at 1 A g−1 after 2000 cycles, demonstrating remarkable long-term cycling properties. Moreover, the kinetic analysis reveals that the increased capacity can be ascribed to an enlarged diffusion-controlled process. In addition, the COMSOL simulation displays the high concentration of Li ions flux on the PI@CNTs surface. This work suggests a facile strategy to fabricate capable hierarchical polymer electrode materials for lithium ion batteries. [ABSTRACT FROM AUTHOR]

Nickel-cobalt nanowire arrays (Ni-Co NWAs) electrode is prepared by one-step galvanostatic electrodeposition with a polycarbonate membrane as the template. By adjusting the Co proportion in the Ni and Co bath solution into 10%, the optimal Ni-Co NWAs electrode in terms of relatively lower onset potential and highest current density towards urea electro-oxidation is obtained. Its catalytic performance is investigated by constructing single direct urea/hydrogen peroxide (H 2 O 2 ) fuel cell. Results show that a peak power density of 7.4 mW cm −2 and an open circuit voltage of 0.92 V are achieved at room temperature when 9.0 mol L −1 KOH and 0.33 mol L −1 urea are used as the anolyte, H 2 SO 4 and H 2 O 2 as the catholyte. Additionally, the urea/H 2 O 2 fuel cell also demonstrates excellent stability during short term duration test. [ABSTRACT FROM AUTHOR]

In this work, Co(OH) 2 buds direct growth on Ni foam (Co(OH) 2 buds/Ni foam) is prepared via a hydrothermal method. Their structure and morphologies are characterized by using X-ray diffraction analysis, scanning electron microscopy and transmission electron microscopy. Result shows that the Co(OH) 2 buds are assembled by several nanorods and uniformly covered on the surface of Ni foam. Due to its unique structure, the Co(OH) 2 buds/Ni foam electrode shows high capacitive performance and long cycle life. The specific capacitance of Co(OH) 2 buds/Ni foam is as high as 2041 F g −1 at a current density of 3 mA cm −2 in 6 M KOH electrolyte, and 811 F g −1 even at a high current density of 60 mA cm −2 . The capacitance of the Co(OH) 2 buds/Ni foam electrode remained 72.4% after 1000 cycles at 18 mA cm −2 . An asymmetric supercapacitor was successfully assembled, in which Co(OH) 2 buds/Ni foam and AC used as positive and negative electrode, respectively. The energy density of the AC//Co(OH) 2 buds/Ni foam supercapacitor reaches to 20.3 W h kg −1 at a power density of 90.6 W kg −1 . Our result shows that the Co(OH) 2 materials are promising candidate for electrochemical energy applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • Nitrogen-rich biomass carbon (N-CHC) was prepared by urea etching method. • N-CHC exhibits excellent capacity and rate performance as a K+ half-cell anode. • Large specific surface area, lots of defects and heteroatoms are key advantages. • The hybrid capacitor composed of N-CHC and AC exhibits high energy and power density. Potassium ion hybrid capacitors have the advantages of high energy density, high power density, and low cost, and are expected to replace expensive lithium ion storage devices in large-scale applications. Here, an innovative nitrogen-rich biomass carbon (N-CHC) is prepared using urea as the etchant and hemp core as the raw material, which has a high specific surface area of 1185.3 m2 g−1 and nitrogen content of 8.56%. In addition, it shows a capacity of 442.4 mAh g−1 as a potassium ion half-cell anode at 30 mA g−1. Even under the high current test of 2000 mA g−1, N-CHC also shows excellent performance (175.0 mAh g−1). Further, the good rate performance is attributed to the large-scale capacitance control by analyzing reaction process kinetics. And the constant current intermittent titration technique (GITT) results show that N-CHC has a larger K+ diffusion coefficient than unetched biomass carbon. The maximum energy density of the full carbon-based hybrid capacitor composed of N-CHC anode and activated carbon cathode is 127.36 Wh kg−1, and the maximum power density is 2371 W kg−1. [ABSTRACT FROM AUTHOR]

• The PTC-S as anode has an outstanding performance in 0.5 M LiCl + 0.5 M MgCl 2 aqueous solution. • The PTC-S exhibits a good rate ability and cycling stability. • PTC-S‖LiMn 2 O 4 has a high capacity and excellent cycling stability. Aqueous batteries are appealing for large-scale storage applications, due to their high safety level, low cost, and excellent durability. In this study, we reported a new anode material, namely sulfur perylene-3,4,9,10-tetracarboxylate (PTC-S), which is more stable than other electrode materials used in aqueous Mg-Li ion batteries. When PTC-S is used as the anode in 0.5 M MgCl 2 + 0.5 M LiCl with a current density of 50 mA g−1, the discharge specific capacity is 287.3 mAh g−1 at the initial cycle and the capacity retention rate is still close to 100% at over 1000 cycles. The monomer structural material conjugated with bifunctional groups can provide the space for the intercalation of Mg2+ and Li+ at the same time, shorten the ion transmission path and accelerate the transmission speed of metal ions in the electrode. In order to develop aqueous battery as quickly as possible, LiMn 2 O 4 and PTC-S are used as cathode and anode materials, respectively, in a dual-ion salt aqueous battery. The PTC-S‖LiMn 2 O 4 battery exhibits a high capacity and an excellent cycling stability performance in aqueous Mg-Li ion battery. The battery has a high capacity performance of 240.0 mAh g−1 at a voltage ranging from 0.0 V to 1.8 V, as well as a high specific energy density of 172.8 Wh kg−1 and remarkable cycling stability. PTC-S in 0.5 M MgCl 2 electrolyte has a current density of 100 mA g−1, a specific discharge capacity of 203 mAh g−1 and a first-cycle Coulomb efficiency close to 100%. Under the same test conditions, the discharge specific capacity is higher than that of the perylene-3,4,9,10-tetracarboxylic dihydride (PTCI) electrode (101 mAh g−1), and the capacity retention rate is increased by 30.4%. [ABSTRACT FROM AUTHOR]

• NiNb 2 O 6 @NC-2 hollow nanoparticles is used as rate capability anode for LICs. • The NiNb 2 O 6 @NC-2 exhibits a high specific capacity of 435.8 mAh g−1 at 50 mA g−1. • NiNb 2 O 6 decomposes into Ni metal and Li x Nb 2 O 6 in the 1st charge/discharge process. • The NiNb 2 O 6 @NC//AC LICs has a maximum energy density of 123.9 Wh kg−1. Searching for anode materials with fast Li+ intercalation kinetics to mitigate the dynamic imbalance with the rapid capacitive cathode is the fundamental strategy to achieve high energy-power density of Li-ion capacitors (LICs). Hence, NiNb 2 O 6 hollow nanoparticles are first synthesized by hydrothermal method and then sealed with a protective N-doped carbon shell to achieve the target NiNb 2 O 6 @NC composite. As the anode of LICs, the NiNb 2 O 6 @NC sample exhibits a high capacity of 435.8 mAh g−1 at 50 mA g−1 and excellent rate performance of 47.8% capacity retention with the current density increased to 2 A g−1. The lithium storage mechanism of NiNb 2 O 6 is proposed as a combined conversion reaction and an intercalation reaction, which the NiNb 2 O 6 decomposes into Ni metal and Li x Nb 2 O 5 during the 1st discharge/charge process. The irreversible Ni would not contribute to the reversible capacity and will improve the electric conductivity for fast transport of electrons and the Li x Nb 2 O 5 will act as the host for lithium ions by means of the intercalation mechanism. Furthermore, the assembled NiNb 2 O 6 @NC//activated carbon LICs exhibit a maximum energy density of 123.9 Wh kg−1 and the capacity retention reaches 86.1% after 5000 cycles. The superior electrochemical performances indicate that the rationally-designed NiNb 2 O 6 @NC is expected to be a potential anode material for LICs. [ABSTRACT FROM AUTHOR]

K-ion batteries (KIBs) are widely considered as a promising alternative to Li-ion batteries (LIBs) due to the cost effective and earth abundant features of K. However, identifying a potential anode for KIBs showing good capacity and stability is still challenging. Because traditional graphite suffers from poor stability owing to the large volume expansion during the insertion/extraction of K ions. Non-graphite carbon is a good candidate because of the disordered nature. A facile high temperature pyrolysis method was adopted to obtain bio-derived carbon materials. Among different kinds of biomass precursors, the porous dandelion seed with nitrogen doping shows the best electrochemical performance with a specific capacity of 168 mAh g−1. The nitrogen-doped carbon presents good K ion adsorption capability and enhanced wettability, which is demonstrated in Fig.S1. Moreover, after introducing activation agent (KOH) in the carbonization process, the capacity in improved to 243 mAh g−1. Meanwhile, the as-prepared carbon material delivers good capacity retention of 91% after 100 cycles. Therefore, the hierarchically porous doped carbon derived from renewable biomass precursor shows great economical potential as KIBs anode. Unlabelled Image • The bio-derived carbon activated by KOH maintain maintain an integrated porous microstructure. • The heteroatoms-doped bio-derived carbon exhibits high specific capacity as K ions anode. • The abundant bio-mass precursor enables large scale preparation of the carbon materials. [ABSTRACT FROM AUTHOR]

High-quality F-doped graphene as rate capability anode for Li-ion battery is prepared by a one-step arc-discharge method. The in-situ formation of LiF nano-particles in the first lithium insertion process enhance the interlayer spacing of graphene, thus provid enough void for rapid ion diffusion, which is capable to deliver much high reversible capacity, outstanding rate performance, and excellent cycling stability. • A high-quality F-modified graphene as rate capability anode for Li-ion battery is reported. • The structural evolution of F-modified graphene electrode during the Li+ insertion/extraction is investigated. • The F-modified graphene delivers a high reversible capacity, outstanding rate performance, and excellent cycling stability. The application of lithium ion battery (LIB) in portable electronics and electric vehicle has received tremendous attention, however, challenges remain in seeking suitable high-capacity anode materials with excellent rate performance and thus potentially to boost the energy/power density. Here we report an arc-discharge production of high-quality F-modified graphene as anode for LIB with high-rate capability. As a result of F-modified, the acquired graphene exhibits high atomic ratio of C/O, excellent electric conductivity and more crumpled and wrinkled surface. Interestingly, the in-situ formation of LiF nanoparticles during the first Li+ insertion process not only act as barriers to effectively prevent the agglomeration and re-stacking of graphene sheets but also enhance the interlayer spacing, thus providing enough void for rapid Li+ ion insertion/extraction. These optimized features enable the resultant F-modified graphene delivers a high reversible capacity (783.2 mAh g−1 at 100 mA g−1), outstanding rate performance (298.5 mAh g−1 at 10 A g−1), and excellent cycling stability (>91% capacity retention after 1000 cycles), providing great application prospect in high-enegy-power LIB. [ABSTRACT FROM AUTHOR]

Rechargeable aqueous aluminum ion batteries (RAAB) have gained increasing attentions for large scale energy storage system due to their high safety, nontoxicity and low cost. However, lack of capable anode materials extremely hinders their potential application. As we all know, the anodic material of aluminum ion battery was limited, we report poly (3,4,9,10-perylentetracarboxylic diimide) (PPTCDI) under the different synthesis conditions as organic anode material for aqueous RAAB. The aluminum ions intercalation/deintercalation storage mechanism is affected by the different electrolyte concentrations. Upon their high capacity and cycling stability, our work would highlight potential application of conjugated polymer organic electrode materials for aqueous aluminum ion batteries. Unlabelled Image • The PPTCDI as anode in aqueous Al-ion battery was reported for the first time. • The Al-ion battery delivers excellent electrochemical cycling stability. • The aluminum ions intercalation/deintercalation storage mechanism is affected by the different concentrations of electrolyte. [ABSTRACT FROM AUTHOR]