Tuning the D-Band Center of Bi2S3─MoS2 Heterostructure Towards Superior Lithium-Sulfur Batteries.

Lithium-sulfur (Li-S) batteries are one of the most promising energy storage devices due to their environmental friendliness, low cost, and high specific capacity. However, the slow electrochemical kinetics and the "shuttle effect" have seriously hindered their commercialization. Herein, the nanoflower Bi2S3─MoS2 (BMS) heterostructure is synthesized by a two-step hydrothermal method, and then the Bi2S3─MoS2-Polypropylene (BMS-PP) interlayer is constructed. The heterostructure is rich in active sites, in which BMS has strong adsorption to lithium polysulfides (LiPSs) and can effectively anchor LiPSs while catalyzing LiPSs and promote the redox of Li2S at the same time, which can improve the utilization of active substances. More importantly, the d-band center can be tuned by the formation of Bi2S3─MoS2 heterostructure. Thus, Li-S batteries containing the BMS-PP interlayer show excellent rate performance (841.6 mAh g-1 at 5 C) and cycling performance (70.3% capacity retention after 500 cycles at 3 C). This work provides a new route for high-performance lithium-sulfur batteries.

Yolk-Shell Structured ST@Al2 O3 Enables Functional PE Separator with Enhanced Lewis Acid Sites for High-Performance Lithium Metal Batteries.

Commercial polymer separators usually have limited porosity, poor electrolyte wettability, and poor thermal and mechanical stability, which can deteriorate the performance of battery, especially at high current densities. In this work, a functional polyethylene (PE) separator is prepared by surface engineering a layer of Ti-doped SiO2 @Al2 O3 particles (denoted as ST@Al2 O3 -PE) with strong Lewis acid property and uniform porous structure on one side of the PE separator. On the other hand, ST@Al2 O3 particles with abundant pore structures and large cavities can store a large amount of electrolyte, providing a shortened pathway for lithium-ion transport, and the Lewis acid sites and porous structure of the ST@Al2 O3 can tune Li plating/stripping behavior and stabilize the lithium metal anode. The ST@Al2 O3 -PE separators exhibit better ionic conductivity (5.55 mS cm-1 ) and larger lithium-ion transference number (0.62). At a current density of 1 mA cm-2 , Li/Li symmetric cells with ST@Al2 O3 -PE separator can be stably cycled for more than 400 h, and both lithium iron phosphate /Li cells and lithium cobaltate/Li cells with ST@Al2 O3 -PE separator have good cycling and rate performance. This work provides a new strategy for developing functional separators and promoting the application of lithium metal batteries.

Catalytic VS2 -VO2 Heterostructure that Enables a Self-Supporting Li2 S Cathode for Superior Lithium-Sulfur Batteries.

Lithium-sulfur batteries (LSBs) have become very promising next-generation energy-storage technologies owing to their high energy densities and cost-effectiveness. However, the poor electrical conductivity of the active material, volume changes that occur during cycling, the "shuttle effect" involving lithium polysulfides (LiPSs), and lithium dendrite growth limit their commercializability. Herein, the preparation of a CC@VS2 -VO2 @Li2 S@C electrode prepared by the in situ growth of a VS2 -VO2 heterostructure on carbon cloth (CC), loaded with Li2 S, and finally coated with a carbon shell, is reported. The cell with the CC@VS2 -VO2 @Li2 S@C cathode exhibits superior cycling stability and rate performance owing to synergy between its various components. The cell delivers a high discharge specific capacity of 919.8 mA g-1 at 0.2 C, with a capacity of 588.9 mAh g-1 retained after 500 cycles with an average capacity attenuation of 0.072% per cycle. The cell exhibits discharge capacities of 937.6, 780.2, 641.9, 541, and 462.8 mAh g-1 at current densities of 0.2, 0.5, 1, 2, and 3 C, respectively. This study provides a new approach for catalyzing LiPS conversion and promoting LSB applications.

NiS/NiCo2 O4 Cooperative Interfaces Enable Fast Sulfur Redox Kinetics for Lithium-Sulfur Battery.

Due to their high energy density and cost-effectiveness, lithium-sulfur batteries (LSBs) are considered highly promising for the next generation of energy storage technologies. However, the soluble lithium-polysulfides (LiPSs) notorious for causing the shuttle effect and the sluggish redox kinetics have hindered their practical commercialization. To tackle these challenges, a heterostructural catalyst featuring NiS-NiCo2 O4 interfaces is developed, which serves as an interlayer for LSBs. These interfacial sites leverage the advantages of polar NiCo2 O4 and conductive NiS, enabling smooth Li+ diffusion, rapid electron transport, and effective immobilization of LiPSs. This synergistic approach promotes the conversion of sulfur species, resulting in a high discharge capacity of 526 mAh g-1 at 3 C for cells with the NiS-NiCo2 O4 interlayer. Additionally, remarkable cycling stability is achievable with an areal sulfur loading of ≈5.0 mg cm-2 . It is believed that this research paves the way for practical applications of LSBs.

Enhanced stability of vanadium-doped Li1.2Ni0.16Co0.08Mn0.56O2 cathode materials for superior Li-ion batteries.

Lithium-manganese-based cathode materials have attracted much attention due to its high specific capacity, but the low initial coulomb efficiency, poor rate performance and voltage attenuation during cycling limit its application. In this work, Li1.2Ni0.16Co0.08Mn0.56-x V x O2 samples (x = 0, 0.005, 0.01, 0.02, 0.05) were prepared using the sol-gel method, and the effects of different V5+ contents on the structure, valence state, and electrochemical performance of electrode materials were investigated. The results show that the introduction of high-valence V5+ in cathode materials can reduce partial Mn4+ to active Mn3+ ions for charge conservation, which not only improves the discharge capacity and coulomb efficiency of Li-rich manganese-based cathode materials, but also inhibits the voltage attenuation. The initial discharge capacity of the Li1.2Ni0.16Co0.08Mn0.55V0.01O2 is as high as 280.9 mA h g-1 with coulomb efficiency of 77.7% at 0.05C, which is much higher than that of the undoped pristine sample (236.6 mA h g-1 with coulomb efficiency of 74.0%). After 100 cycles at 0.1C, the capacity retention rate of Li1.2Ni0.16Co0.08Mn0.55V0.01O2 was 92.3% with the median voltage retention rate of 95.6%. This work provides a new idea for high performance of lithium-rich manganese-based cathode materials.

Toward highly efficient bifunctional electrocatalysts for zinc-air batteries: from theoretical prediction to a ternary FeCoNi design.

3d Transition-metal nitrogen-carbon nanocomposites (T-N-C, T = Fe, Co, Ni, etc.) with highly active M-Nx sites have received much attention in the field of rechargeable zinc-air battery research. However, how to rationally dope metallic elements to decorate T-N-C catalysts and enhance their electrocatalytic performances remains unclear. Herein, we demonstrated that cobalt-doped Fe-rich catalysts are effective in improving ORR performances by density functional theory (DFT) calculations. On this basis, we reported a kind of novel bifunctional electrocatalyst of hollow nitrogen-doped carbon tubes with coexisting M-N-C single atoms and alloy nanoparticles (denoted FexCoyNiz@hNCTs). Benefiting from the synergistic effect between different components, the as-prepared Fe4Co1Ni2@hNCT catalyst exhibited a small overpotential difference of 0.75 V between an OER potential at 10 mA cm-2 and an ORR half-wave potential, as well as an excellent zinc-air battery performance, when serving as the air cathode. This work provided a scalable design concept for multi-metal doping toward high-performance T-N-C electrocatalysts.

In Situ Electrochemical Activation Derived Lix MoOy Nanorods as the Multifunctional Interlayer for Fast Kinetics Li-S batteries.

Li-S batteries (LSBs) have attracted worldwide attention owing to their characteristics of high theoretical energy density and low cost. However, the commercial promotion of LSBs is hindered by the irreversible capacity decay and short cycling life caused by the shuttle effect of lithium-polysulfides (LiPSs). Herein, a hybrid interlayer consisting of MoO3 , conductive Ni foam, and Super P is prepared to prevent the shuttle effect and catalyze the LiPSs conversion. MoO3 with a reversible lithiation/delithiation behavior between Li0.042 MoO3 and Li2 MoO4 within 1.7-2.8 V versus Li/Li+ combines the Li+ insertion and LiPSs immobilization and efficiently improve the LSBs redox kinetics. Benefiting from the reversible Li+ insertion/extraction in lithium molybdate (Lix MoOy ) and the highly conductive Ni foam substrate, the sulfur cathode coupled with such electrochemical activation derived catalytic interlayer exhibits a high initial discharge capacity of 1100.1 mAh g-1 at a current density of 1 C with a low decay rate of 0.09% cycle-1 . Good capacity retention can still be obtained even the areal sulfur loading is increased to 13.28 mg cm-2 .