Lithium metal is regarded as one of the most promising candidates for next-generation batteries. However, lithium dendrite formation and dead lithium accumulation are the critical problems which hinder its practical application. Herein, we constructed a flexible coating membrane layer which could effectively uniform the lithium deposition by isolating lithium metal from electrolyte and regulating the ion flux distribution. After modification, both the Li||Li symmetric cells (more than 1,400 h at 1 mA·cm⁻² and 1 mAh·cm⁻²) and Li||Cu cells (more than 500 cycles at 0.5 mA·cm⁻² and 0.5 mAh·cm⁻², coulombic efficiency over 98%) deliver excellent long-cycle performance with high coulombic efficiency. The high performance is also proved in LiFePO₄ (capacity retention increases from 79% to 93% at 2 C after 400 cycles) and NCM811 full cells (capacity retention from 28.5% to 78% at 2 C after 500 cycles). High electro-performance in batteries demonstrates that the multifunctional layer plays a crucial role in stabilizing lithium anode. Moreover, in order to verify the universality of the method, we have extended this facile way to fabricate other types of flexible membranes. This work offers an insight into solving the current obstacles in the application of lithium metal batteries.

Sulfur-host material with abundant pore structure and high catalysis plays an important role in development of high-energy-density lithium–sulfur (Li–S) batteries. Herein, we implanted NiCoP nanoparticles into the N,S co-doped porous carbon derived from petroleum coke (PCPC) to fabricate the sulfur-host of PCPC/NiCoP composites. The high specific surface area of PCPC provides abundant adsorption sites for capturing LiPSs and the NiCoP nanoparticles to improve the polarity and boost the LiPSs conversion kinetics of PCPC. The Li–S cells fabricated with PCPC/NiCoP as sulfur-host deliver high discharge capacity of 1,462.7 mAh·g⁻¹ under the current density of 0.1 C and exhibit ultralong lifespan over 800 cycles under the current density of 1, 2, and even 5 C. Additionally, the prepared composites cathodes deliver an outstanding discharge capacity of 932.5 and 826.4 mAh·g⁻¹ at 0.5 and 1 C with a high sulfur loading of over 3.90 mg·cm⁻², and remain stable about 60 cycles. Furthermore, the promoted adsorption-conversion process of polysulfides by introducing NiCoP nanoparticles into PCPC was investigated by experimental and theoretical calculation studies. This work offers a new light for tacking the obstacles of porous carbon-based sulfur-host and propelling the development of petroleum coke-based porous carbon for high performance Li–S batteries.

Potassium-ion batteries (PIBs) are promising candidates for next-generation energy storage devices due to the earth abundance of potassium, low cost, and stable redox potentials. However, the lack of promising high-performance electrode materials for the intercalation/deintercalation of large potassium ions is a major challenge up to date. Herein, we report a novel uniform nickel selenide nanoparticles encapsulated in nitrogen-doped carbon (defined as pNiSe@NCq) as an anode for PIBs, which exhibits superior rate performance and cyclic stability. Benefiting from the unique hierarchical core-shell like nanostructure, the intrinsic properties of metal-selenium bonds, synergetic effect of different components, and a remarkable pseudocapacitance effect, the anode exhibits a very high reversible capacity of 438 mAdhdg^-1 at 50 mAdg^-1, an excellent rate capability, and remarkable cycling performance over 2, 000 cycles. The electrochemical mechanism were investigated by the in-situ X-ray diffraction, ex-situ high-resolution transmission electron microscopy, selected area electron diffraction, and first principle calculations. In addition, NiSe@NC anode also shows high reversible capacity of 512 mAdhdg^-1 at 100 mAdg^-1 with 84% initial Coulombic efficiency, remarkable rate performance, and excellent cycling life for sodium ion batteries. We believe the proposed simple approach will pave a new way to synthesize suitable anode materials for secondary ion batteries.

Sodium-ion batteries (SIBs) and potassium-ion batteries (PIBs) have been considered as attractive alternatives for next-generation battery systems, which have promising application potential due to their earth abundance of potassium and sodium, high capacity and suitable working potential, however, the design and application of bi-functional high-performance anode still remain a great challenge up to date. Bismuth sulfide is suitable as anode owing to its unique laminar structure with relatively large interlayer distance to accommodate larger radius ions, high theoretical capacity and high volumetric capacity etc. In this study, dandelion-like Bi₂S₃/rGO hierarchical microspheres as anode material for PIBs displayed reversible capacity, and 206.91 mAh·g^–1 could be remained after 1, 200 cycles at a current density of 100 mA·g^–1. When applied as anode materials for SIBs, 300 mAh·g^–1 could be retained after 300 cycles at 2 A·g^–1 and its initial Coulombic efficiency is as high as 97.43%. Even at high current density of 10 A·g^–1, 120.3 mAh·g^–1 could be preserved after 3, 400 cycles. The Na₃V₂(PO₄)₃@rGO//Bi₂S₃/rGO sodium ion full cells were successfully assembled which displays stable performance after 60 cycles at 100 mA·g^–1. The above results demonstrate that Bi₂S₃/rGO has application potential as high performance bi-functional anode for PIBs and SIBs.

A series of bimetallic nickel cobalt sulfides with hierarchical micro/nano architectures were fabricated via a facile synthesis strategy of bimetallic micro/nano structure precursor construction-anion exchange via solvothermal method. Among the nickel cobalt sulfides with different Ni/Co contents, the coral-like Ni_1.01Co_1.99S₄ (Ni/Co, 1/2) delivers ultrafast and stable Na-ion storage performance (350 mAh·g⁻¹ after 1, 000 cycles at 1 A·g⁻¹ and 355 mAh·g⁻¹ at 5 A·g⁻¹). The remarkable electrochemical properties can be attributed to the enhanced conductivity by co-existence of bimetallic components, the unique coral-like micro/nanostructure, which could prevent structural collapse and self-aggregation of nanoparticles, and the easily accessibility of electrolyte, and fast Na⁺ diffusion upon cycling. Detailed kinetics studies by a galvanostatic intermittent titration technique (GITT) reveal the dynamic change of Na⁺ diffusion upon cycling, and quantitative kinetic analysis indicates the high contribution of pseudocapacitive behavior during charge–discharge processes. Moreover, the ex-situ characterization analysis results further verify the Na-ion storage mechanism based on conversion reaction. This study is expected to provide a feasible design strategy for the bimetallic sulfides materials toward high performance sodium-ion batteries.

Hollow spheres of Co_0.85Se constructed by two-dimensional (2D) mesoporous ultrathin nanosheets were synthesized via simple and cost effective approach. Their bifunctional electrocatalytic-supercapacitive properties were obtained simultaneously due to synergistic effects between macroscopic morphological features and microscopic atomic/electronic structure of Co_0.85Se. The as-synthesized hollow spheres of Co_0.85Se that are constructed by 2D mesoporous ultrathin nanosheets exhibit inspiring electrochemical performance for supercapacitor, presenting maximum energy density at high power density (54.66 Wh·kg^-1 at 1.6 kW·kg^-1) and long cycle stability (88% retention after 8, 000 cycles). At the same time, the hollow spheres of Co_0.85Se constructed by 2D mesoporous ultrathin nanosheets display excellent catalytic performance for oxygen evolution reaction (OER) due to special structure, high surface area and mesoporous nature of sheets, which achieve low overpotential (290 mV at 10 mA·g^-1) and low Tafel slope (81 mV·dec^-1) for long-term operation (only 7.8% decay in current density after 9 h). It could be envisioned that the proposed simple approach will pave a new way to synthesize other metal chalcogenides for energy conversion and storage technology.

Lithium–sulfur (Li–S) battery as one of the most attractive candidates for energy storage systems has attracted extensive interests. Herein, for the first time, hierarchical flower-like cobalt phosphosulfide architectures (defined as "CoSP") derived from Prussian blue analogue (PBA) was fabricated through the conversion of Co-based PBA in P_xS_y atmosphere. The as-prepared polar CoSP could effectively trap polysulfides through the formation of strong chemical bonds. In addition, after the combination of CoSP with high conductive rGO, the obtained CoSP/rGO as sulfur host material exhibits ultralow capacity decay rate of 0.046% per cycle over 900 cycles at a current density of 1 C. The excellent performance could be attributed to the shortened lithium diffusion pathways, fastened electron transport ability during polysulfide conversion, and increased much more anchor active sites to polysulfides, which is expected to be a promising material for Li-S batteries. It is believed that the as-prepared CoSP/rGO architectures will shed light on the development of novel promising materials for Li-S batteries with high cycle stability.

Mesoporous Mn-Sn bimetallic oxide (BO) nanocubes with sizes of 15-30 nm show outstanding stable and reversible capacities in lithium ion batteries (LIBs), reaching 856.8 mAh·g^-1 after 400 cycles at 500 mA·g^-1 and 506 mAh·g^-1 after 850 cycles at 1, 000 mA·g^-1. The preliminary investigation of the reaction mechanism, based on X-ray diffraction measurements, indicates the occurrence of both conversion and alloying-dealloying reactions in the Mn-Sn bimetallic oxide electrode. Moreover, Mn-Sn BO//LiCoO₂ Li-ion full cells were successfully assembled for the first time, and found to deliver a relatively high energy density of 176.25 Wh·kg^-1 at 16.35 W·kg^-1 (based on the total weight of anode and cathode materials). The superior long-term stability of these materials might be attributed to their nanoscale size and unique mesoporous nanocubic structure, which provide short Li⁺ diffusion pathways and a high contact area between electrolyte and active material. In addition, the Mn-Sn BOs could be used as advanced sulfur hosts for lithium-sulfur batteries, owing to their adequate mesoporous structure and relatively strong chemisorption of lithium polysulfide. The present results thus highlight the promising potential of mesoporous Mn-Sn bimetallic oxides for application in Li-ion and Li-S batteries.

Lithium-sulfur batteries are promising electrochemical energy storage devices because of their high theoretical specific capacity and energy density. An ideal sulfur host should possess high conductivity and embrace the physical confinement or strong chemisorption to dramatically suppress the polysulfide dissolution. Herein, uniform TiN hollow nanospheres with an average diameter of ~160 nm have been reported as highly efficient lithium polysulfide reservoirs for high-performance lithium-sulfur batteries. Combining the high conductivity and chemical trapping of lithium polysulfides, the obtained S/TiN cathode of 70 wt.% sulfur content in the composite delivered an excellent long-life cycling performance at 0.5C and 1.0C over 300 cycles. More importantly, a stable capacity of 710.4 mAh·g?1 could be maintained even after 100 cycles at 0.2C with a high sulfur loading of 3.6 mg·cm?1. The nature of the interactions between TiN and lithium polysulfide species was investigated by X-ray photoelectron spectroscopy studies. Theoretical calculations were also carried out and the results revealed a strong binding between TiN and the lithium polysulfide species. It is expected that this class of conductive and polar materials would pave a new way for the high-energy lithium-sulfur batteries in the future.

NaFeTiO₄ nanorods of high yields (with diameters in the range of 30–50 nm and lengths of up to 1–5 μm) were synthesized by a facile sol–gel method and were utilized as an anode material for sodium-ion batteries for the first time. The obtained NaFeTiO₄ nanorods exhibit a high initial discharge capacity of 294 mA·h·g^-1 at 0.2 C (1 C = 177 mA·g^–1), and remain at 115 mA·h·g^–1 after 50 cycles. Furthermore, multi-walled carbon nanotubes (MWCNTs) were mechanically milled with the pristine material to obtain NaFeTiO₄/MWCNTs. The NaFeTiO₄/ MWCNTs electrode exhibits a significantly improved electrochemical performance with a stable discharge capacity of 150 mA·h·g^–1 at 0.2 C after 50 cycles, and remains at 125 mA·h·g^–1 at 0.5 C after 420 cycles. The NaFeTiO₄/MWCNTs//Na₃V₂(PO₄)₃/C full cell was assembled for the first time; it displays a discharge capacity of 70 mA·h·g^-1 after 50 cycles at 0.05 C, indicating its excellent performances. X-ray photoelectron spectroscopy, ex situ X-ray diffraction, and Raman measurements were performed to investigate the initial electrochemical mechanisms of the obtained NaFeTiO₄/MWCNTs.