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Problems of practical sodium-ion batteries.

The BP@Ni3Se4/CoSe2 heterostructure delivers superior sodium storage performance with long cycling stability and high energy density.

Titanium niobium oxide as an electrode material for lithium-ion batteries (LIBs) has relatively high working potential and theoretical capacity, which is expected to replace a graphite anode.

An interfacial covalent bonding strategy is proposed to synthesize the MXene-stabilized Sb2Se3 nanotube hybrid.

The shortage of high-capacity anode materials with long cycling stability is the main roadblock to the development of sodium-ion batteries (SIBs). The advantages of transition metal selenides are high theoretical capacity, safety and ease of design, which gradually make them potential substitute materials for the anodes of a new generation of SIBs. However, the low intrinsic conductivity of transition metal selenides and the serious powderization during charge and discharge processes restrict their rate performance and cycling stability in SIBs. Herein, bimetallic selenide ZnSe/MoSe

A CoSe2/N-doped carbon heterojunction with a three-dimensional porous structure is synthesized via a topological transformation process, which delivers superior sodium storage performance.

The electrochemical kinetics of vanadium diphosphide is regulated by the phosphorus–carbon covalent bond to boost the sodium storage performance.

Multi-ion co-pre-intercalated hydrated vanadate microflowers with a robust crystal structure from vanadium slag waste are developed, which present highly reversible and ultrafast Zn2+ storage ability at room temperature and −20 °C.

Highly dispersive CoSe2 nanoparticles encapsulated in carbon nanotube-grafted multichannel carbon fibers are synthesized through a confined-regulated interfacial engineering strategy, which delivers excellent electrochemical performance.

Plastic wastes are converted into two-dimensional carbon nanosheets with a graphitic-like structure and interlayer channels for improved solar evaporation performance.

With the in-depth research of sodium-ion batteries (SIBs), the development of novel sodium-ion anode material has become a top priority. In this work, tube cluster-shaped SbPS4 was synthesized by a high-temperature solid phase reaction. Then the typical short tubular ternary thiophosphate SbPS4 compounded with graphene oxide (SbPS4/GO) was successfully synthesized after ultrasonication and freeze-drying. SbPS4 shows a high theoretical specific capacity (1335 mAh/g) according to the conversion-alloying dual mechanisms. The unique short tube inserted in the spongy graphene structure of SbPS4/GO results in boosting the Na ions transport and alleviating the huge volume change in the charging and discharging processes, improving the sodium storage performance. Consequently, the tubular SbPS4 compounded with 10% GO provides an outstanding capacity of 359.58 mAh/g at 500 mA/g. The result indicates that SbPS4/GO anode has a promising application potential for SIBs.

Transition metal selenides (TMS) are compounds composed of transition metals and selenium, and they offer a range of chemical and structural diversity that can be exploited to optimize their performance...

High-entropy alloys (HEAs) have been attracting extensive research interests in designing advanced nanomaterials, while their precise control is still in the infancy stage. Herein, we have reported a well-defined PtBiPbNiCo hexagonal nanoplates (HEA HPs) as high-performance electrocatalysts. Structure analysis decodes that the HEA HP is constructed with PtBiPb medium-entropy core and PtBiNiCo high-entropy shell. Significantly, the HEA HPs can reach the specific and mass activities of 27.2 mA cm

Sodium-ion batteries (SIBs) have aroused great attention because of the low cost and environmental benignity of sodium resources. However, practical applications of SIBs are plagued by the sluggish kinetics of sodium ions with large size in the host structure, which results in poor rate performance and rapid capacity decline. Herein, a self-templated approach was developed to synthesize MoS2 /Cu2 Se nanosheets with improved interfacial electron- and ion-transfer kinetics. The MoS2 /Cu2 Se nanosheets provided superior sodium storage performance, delivering 139 mAh g-1 at a high current density of 100 A g-1 and 222 mAh g-1 after 14000 cycles (at 20 A g-1 ). The outstanding electrochemical performance was attributed to the synergetic engineering of interface and structure, which could enhance the electrochemical kinetics and gave excellent mechanical properties to deal with the volume expansion phenomenon. Combined with a high-voltage cathode, the full battery demonstrated a high energy density of 152 Wh kg-1 at a power density of 420 W kg-1 , which opens a new avenue for the development of high-performance SIBs.

The high-temperature sodium-ion batteries (SIBs) used for large-scale energy storage have attracted extensive attention in recent years. However, the development of SIBs is still hampered mainly by their poor charge/discharge efficiency and stability, necessitating the search for appropriate electrodes. A simple potassium ion intercalation process is used herein to obtain the potassium vanadate (KV3O8) nanobelts. When serving as the anode for SIBs at a high temperature (60°C), the KV3O8 nanobelts display superior sodium storage performance with a high capacity of 414 mA h g−1 at 0.1 A g−1, remarkable rate capability (220 mA h g−1 at 20 A g−1), and super-long cycle life (almost no capacity fading at 10 A g−1 over 1000 cycles). Moreover, the ex-situ X-ray powder diffraction reveals no structural changes throughout the whole charge/discharge process, which further confirms their outstanding stability, indicating KV3O8 nanobelts are a promising candidate for high-temperature SIBs.

Crystal phase engineering is an important strategy for designing noble-metal-based catalysts with optimized activity and stability. From the thermodynamic point of view, it remains a great challenge to synthesize unconventional phases of noble metals. Here, a new class of Pd-based nanostructure with unconventional rhombohedral Pd

Metal phosphates have been widely explored in lithium ion batteries and sodium ion batteries owing to high theoretical capacities, mild toxicity and low cost. However, their potassium ion battery applications are less reported due to the limited conductivity and the slow diffusion kinetics. Considering these drawbacks, novel structured M2 P2 O7 /C (M=Fe, Co, Ni) nanoflake composites are prepared through an organic-phosphors precursor-assisted solvothermal method and a subsequent high temperature annealing process. The designed Co2 P2 O7 /C composite exhibits the highest rate capacity with 502 mAh g-1 at 0.1 A g-1 and good cyclability for 900 cycles at 1 A g-1 and 2 A g-1 when compared with Ni and Fe based composites. The superior electrochemical performance can be attributed to their unique nanoparticle-assembled nanoflake structure, which can afford enough active sites for K+ intercalation. In addition, the robust pyrophosphate crystal structure and the in situ formed carbon composition also have positive effects on enhancing the long-term cycling performance and the electrode's conductivity. Finally, this organic-phosphors precursor induced simple approach can be applied for easy fabrication of other pyrophosphate/carbon hybrids as advanced electrodes.

Transition metal selenides have attracted enormous research attention as anodes for lithium-ion batteries (LIBs) due to their high theoretical specific capacities. Nevertheless, the low electronic conductivity and dramatic volume variation in electrochemical reaction processes result in rapid capacity fading and poor rate capability. Herein, a metal–organic framework is used as a template to in situ synthesize Sb2Se3 nanoparticles encapsulated in N-doped carbon nanotubes (N-CNTs) grafted on reduced graphene oxide (rGO) nanosheets. The synergistic effects of N-doped carbon nanotubes and reduced graphene oxide nanosheets are beneficial for providing good electrical conductivity and maintaining the structural stability of electrode materials, leading to stable cycling performance and superior rate performance. Kinetic analysis suggests that the electrochemical reaction kinetics is dominated by pseudocapacitive contribution. Notably, a high discharge capacity of 451.1 mA h g−1 at a current density of 2.0 A g−1 is delivered after 450 cycles. Even at a high current density of 10.0 A g−1, a discharge capacity of 192.6 mA h g−1 is maintained after 10 000 cycles. When coupled with a commercial LiFePO4 cathode, the full batteries show an excellent discharge specific capacity of 534.5 mA h g−1 at 0.2 A g−1. This work provides an effective strategy for constructing high-performance anodes for Li+ storage.

In comparison with lithium-ion batteries, sodium-ion batteries (SIBs) have been proposed as an alternative for large-scale energy storage. However, finding an anode material that can overcome the sluggish electrochemical reaction kinetics and fast capacity fading caused by large volume expansion during cycling is problematic. In this study, the intercalation technique for nitrogen-doped carbon layers is implemented for the molybdenum disulfide (MoS2/NC) structure to improve the rate and cycling stability of SIBs by increasing the diffusion rate of sodium ions and mitigating excessive volume structural expansion. The as-synthesized MoS2/NC anode has a high discharge specific capacity of 546 mA h g-1 at 1 A g-1 after 160 cycles, as well as a high rate and stable cycle performance of 406 mA h g-1 at 10 A g-1 after 1000 cycles. Upon coupling with a high-voltage Na3V2(PO4)2O2F cathode, the sodium-ion full battery displays high specific energies of 78.57 W h kg-1 and 49.70 W h kg-1 at specific powers of 193.76 W kg-1 and 3756.80 W kg-1, respectively, with commercialization potential demonstrated.

Searching for suitable and efficient anode materials is one of the crucial prerequisites for the successful large-scale application of sodium ion batteries (SIBs). In this work, a facile strategy is proposed to encapsulate bismuth phosphosulfide nanoparticles within hollow multi-channel carbon nanofibers (BiPS4@MCNFs) for remarkably enhancing the sodium storage properties. The synergistic effect between the highly dispersed BiPS4 nanoparticles and the multi-channel hollow carbon matrix can effectively improve the utilization of the active materials, alleviate the volume changes and promote mass/charge transfer, thereby resulting in outstanding cycling stability (about 410 mA h g−1 after 1000 cycles at 1 A g−1) and high rate performance. Both the sodium storage mechanism and its potential as the sodium host in full cells are further investigated. Furthermore, the sodium diffusion coefficient has also been analyzed and the three-dimensional (3D) sodium ion diffusion pathways are identified via first-principles calculations. These results demonstrate that the unique BiPS4@MCNFs could be a competitive candidate anode for SIBs.

Sodium-ion batteries (SIBs) have been considered as promising candidates for large-scale energy storage. However, viable anode materials still suffer from sluggish electrochemical reaction kinetics and huge volume expansion during cycling, resulting in rapid capacity fading. Herein, an interface confined strategy is developed to construct MoS2/black phosphorus heterostructure, in which the ultrathin MoS2 nanosheets are well grown on the black phosphorus flakes through strong interface interactions. The synergistic effect of the MoS2 nanosheets and black phosphorus flakes is beneficial to enhancing the electron/ion transport kinetics and improving the structure stability upon cycling, leading to superior sodium storage performance. Specifically, the as-synthesized MoS2/black phosphorus heterostructure shows a high reversible capacity of 435.5 mA h g−1 at 1.0 A g−1 over 150 cycles and a good rate at 10 A g−1 as well as excellent cyclic stability up to 1000 cycles. With the aid of kinetic tests and density functional theory calculations, the sodium storage mechanism can be unraveled. When coupled with the high-voltage Na3V2(PO4)2O2F cathode, the full cell delivers a high energy density of 142.9 W h kg−1 at 76.5 W kg−1, suggesting that the MoS2/black phosphorus heterostructure is a promising candidate to build high-performance SIBs with high energy density and high power density.

Developing high-rate and durable anode materials for sodium-ion batteries (SIBs) is still a challenge because of the larger ion radius of sodium compared with the lithium ion during charge-discharge processes. Herein, NiTe2 coupled with N-doped carbon (NiTe2/NC) hexagonal nanosheets has been fabricated through a solvothermal and subsequent carbonisation strategy. This unique hexagonal nanosheet structure offers abundant active sites and contact area to the electrolyte, which could shorten the Na+ diffusion path. The heterostructured N-doping carbon improves the electrochemical conductivity and accelerates the kinetics of Na+ transportation. Electrochemical analysis shows that the charge-discharge process is controlled by the pseudocapacitive behavior thus leading to high-rate capability and long lifespan in half batteries. As expected, high capacities of 311 mA h g-1 to 217 mA h g-1 at 5 A g-1 to 10 A g-1 are maintained after 800 and 1200 cycles, respectively. Furthermore, a full battery equipped with a Na3V2(PO4)2O2F cathode and a NiTe2/NC anode offers a maximum energy density of 104 W h kg-1 and a maximum power density of 9116 W kg-1. The results clearly show that the NiTe2/NC hexagonal nanosheet with superior Na storage properties is an advanced new material for energy storage systems.

Developing advanced anode materials with high capacity, and good rate and cycling performance for sodium-ion batteries still remains a major challenge at the moment. Herein, it is demonstrated that the introduction of nitrogen elements into CoSe2 yolk–shell spheres (N-CoSe2 yss) with rapid electrochemical kinetics contributes to excellent sodium storage performance. Specifically, the N-CoSe2 yss deliver a high capacity of 431 mA h g−1 at a high current density of 50 A g−1 and a high reversible capacity of 500 mA h g−1 after 1000 cycles at 10 A g−1 with nearly 100% coulombic efficiency. Experimental and density functional theory calculation results indicate that the superior electrochemical performance can be attributed to the synergistic effect of nitrogen doping and structure engineering, which can not only enhance the electronic/ion transport kinetics, but also improve the structural stability during cycling. When coupled with a high-voltage cathode, the full cell shows a high energy density of 129.38 W h kg−1 at a power density of 187.5 W kg−1, confirming the potential applications of N-CoSe2 yss in high-performance sodium-ion batteries.

The hydrogen oxidation reaction (HOR) has recently attracted great attention, yet the poor performance of HOR over the platinum group metal-free (PGMs-free) catalysts in alkaline conditions strongly impedes the development of hydroxide-exchange membrane fuel cells. Here, we demonstrate that the phase and interface engineering of nickel carbide (Ni3C) nanobranches can significantly enhance the alkaline HOR performance. Specifically, such interface engineering is realized through a facile annealing treatment of a branched Ni3C nanostructure. As a promising PGMs-free HOR catalyst, the strong interfacial synergy of Ni/Ni3C significantly enhances the HOR performance in alkaline media, with the HOR activity being comparable to that of a commercial Pt/C catalyst, and it demonstrates excellent CO tolerance. Mechanism studies show that the interfacial synergy facilitates electron transfer from Ni to Ni3C and thus regulates the absorption strengths of *H and *OH. This work opens up a new avenue for the design of high-performance PGM-free catalysts for electrocatalysis and beyond.

Owing to their large theoretical capacity and relatively high electronic conductivity, transition metal selenides have been investigated as potential anodes for energy storage applications. On the other hand, the quick capacity decline induced by volume expansion during cycling and unconnected conducting network of the transition metal selenide-based electrode severely limit their employment in sodium-ion batteries (SIBs). Herein, a simple solvent ultrasonic technique and pyrolysis selenation process were used to make a porous N-doped carbon nanosheet-supported FeSe2/CoSe2 electrode. The electrochemical kinetics could be improved, and the stress generated by volume expansion could be efficiently adjusted by exquisitely constructed boundary of the FeSe2/CoSe2-CN electrode. As expected, the FeSe2/CoSe2-CN porous nanosheets exhibited a high Na+ storage capacity of 350 mA h g−1 (10 A g−1, 1000 cycles). Kinetic studies were conducted to explore the Na+ storage mechanism of FeSe2/CoSe2-CN. The as-constructed full sodium-ion batteries, when combined with Na3V2(PO4)2O2F, have a phenomenal energy density (109 W h kg−1), encouraging the exploration of energy-related components with the high-energy density properties.

Transition metal selenides as anode materials hold great promise in obtaining outstanding sodium-ion batteries. However, the dramatic volume change of transition metal selenides causing poor rate capacity and inferior cycling performance limits their practical application in sodium ion batteries. In this work, a confined-regulated interfacial engineering strategy for the growth of cobalt selenide nanosheets on ultrathin carbon flakes is reported (denoted as CoSe2-CNS). The strong interfacial interaction between CoSe2 and carbon flakes endows CoSe2-CNS with fast electron/sodium ion transport kinetics and good structural stability, thus delivering superior rate capability (352 mA h g−1 at 10 A g−1) and excellent cycling durability. Furthermore, various ex situ characterization techniques and first-principles calculations have been used to unravel the sodium ion storage mechanism of CoSe2-CNS. Impressively, the CoSe2-CNS//NVPOF full cell, which is assembled by combining the CoSe2-CNS anode with a Na3V2(PO4)2O2F (denoted as NVPOF) cathode, exhibits a high capacity of ∼275 mA h g−1 at 0.1 A g−1. Moreover, the assembled full sodium-ion battery possesses the maximum energy density of 115 W h kg−1 and a peak power density of 9214 W kg−1, making CoSe2-CNS a promising anode material for high-performance sodium-ion batteries.

Zinc-ion batteries (ZIBs) are a main focus worldwide for their potential use in large-scale energy storage due to their abundant resources, environmental friendliness, and high safety. However, the cathode materials of ZIBs are limited, requiring a stable host structure and fast Zn2+ channel diffusion. Here, we develop a strategy for the intercalation of polyethylene glycol (PEG) to facilitate Zn2+ intercalation and to suppress the dissolution of vanadium in V2O5. In particular, PEG-V2O5 shows a high capacity of 430 mA h g-1 at a current density of 0.1 A g-1 as well as excellent 100 mA h g-1 specific capacity after 5000 cycles, with a high current density of 10.0 A g-1. A reversible capacity of 81 mA h g-1 can even be achieved with a low temperature of -20 °C at a current density of 2.0 A g-1 after 3500 cycles. The superior electrochemical performance comes from the intercalation of PEG molecules, which can improve kinetic transport and structural stability during the cycling process. The Zn2+ storage mechanism, which provides essential guidelines for the development of high-performance ZIBs, can be found through various ex situ characterization technologies and density functional density calculations.

Cobalt sulfides have been popularly used in energy storage because of their high theoretical capacity and abundant redox reactions. However, poor reaction kinetics, rapid capacity decay, and severe polarization owing to volume changes during electrochemical reaction are still huge challenges for cobalt sulfides in practical applications. Herein, cobalt sulfide yolk-shell spheres were synthesized by phosphorus doping (P-CoS) to stabilize the structure of cobalt sulfides and improve their electronic/ion conductivity. Kinetic tests and density functional theory calculations confirm that the introduction of phosphorus into cobalt sulfides greatly reduces the diffusion barrier of Li+ in the intrinsic structure, thereby improving the reaction kinetics of electrode materials during the Li+ insertion/extraction process. In consequence, the P-CoS electrode delivers a high lithium storage capacity (781 mAh g-1 after 100 cycles at 0.2 A g-1 ), excellent rate capability (489 mAh g-1 at 10 A g-1 ), and outstanding cycling stability (no significant capacity decay over 4000 cycles at 5 A g-1 ). Especially for sodium-ion battery application, the P-CoS electrode expresses a striking capacity of approximately 260 mAh g-1 at 2 A g-1 after 900 cycles.