Fe-cation Doping in NiSe2 as an Effective Method of Electronic Structure Modulation towards High-Performance Lithium-Sulfur Batteries

The commercialization of Li-S batteries is hindered by the shuttling of lithium polysulfides (LiPSs), the sluggish sulfur redox kinetics as well as the low sulfur utilization during charge/discharge processes. Herein, a free-standing cathode material was developed, based on Fe-doped NiSe₂ nanosheets grown on activated carbon cloth substrates (Fe-NiSe₂ /ACC) for high-performance Li-S batteries. Fe-doping in NiSe₂ plays a key role in the electronic structure modulation of NiSe₂ , enabling improved charge transfer with the adsorbed LiPSs molecules, stronger interactions with the active sulfur species and higher electrical conductivity. Effective promotion of the sulfur redox kinetics and enhanced sulfur utilization were achieved under high areal sulfur loadings. The stronger interactions with LiPSs together with the unique 3D structure of Fe-NiSe₂ /ACC also induced the transformation of Li₂ S₂ /Li₂ S growth from conventional 2D films to 3D particles, significantly eliminating the barriers of solid nucleation and growth during the phase transition of liquid LiPSs to solid Li₂ S₂ /Li₂ S. With a high sulfur loading of 9.9 mg cm^-2 , the Fe-NiSe₂ /ACC cathode enabled a high area capacity of 9.14 mAh cm^-2 with a low average decay of 0.11 % per cycle over 200 cycles at 0.1 C.

An inverse opal Cu2Nb34O87 anode for high-performance Li+ storage

Inverse opal Cu₂Nb₃₄O₈₇ with highly-ordered macropores and thin walls is exploited as a practical anode material for high-performance Li⁺ storage.

Nanosheet-based Nb12O29 hierarchical microspheres for enhanced lithium storage

Conductive Nb12O29 hierarchical microspheres with nanosheet shells were synthesized based on a hydrothermal process and a high-temperature hydrogen reduction treatment. The obtained materials demonstrated comprehensively good electrochemical properties, including a significant pseudocapacitive contribution, safe operating potential, high reversible capacity, superior initial coulombic efficiency, increased rate capability, and durable cycling stability.

Surface intercalated spherical MoS2xSe2(1−x) nanocatalysts for highly efficient and durable hydrogen evolution reactions

Surface intercalated spherical MoS_2xSe_2(1−x) nanocatalysts with large numbers of defects and edge areas phase transition, and increased surface roughness significantly improved the HER catalytic activity.

Urchin-like NiO-NiCo2O4 heterostructure microsphere catalysts for enhanced rechargeable non-aqueous Li-O2 batteries

Urchin-like NiO-NiCo2O4 microspheres with heterostructures were successfully synthesized through a facile hydrothermal method, followed by thermal treatment. The unique structure of NiO-NiCo2O4 with the synergetic effect between NiCo2O4 and NiO, and the heterostructure favour the catalytic activity towards Li-O2 batteries. NiCo2O4 is helpful for boosting both the oxygen reduction reaction and oxygen evolution reaction for the Li-O2 batteries and NiO is likely to promote the decomposition of certain by-products. The special urchin-like morphology facilitates the continuous oxygen flow and accommodates Li2O2. Moreover, benefitting from the heterostructure, NiO-NiCo2O4 microspheres are able to promote the transport of Li ions and electrons to further improve battery performance. Li-O2 batteries utilizing a NiO-NiCo2O4 microsphere electrode show a much higher specific capacity and a lower overpotential than those with a Super P electrode. Moreover, they exhibit an enhanced cycling stability. The electrode can be continuously discharged and charged without obvious terminal voltage variation for 80 cycles, as the discharge capacity is restricted at 600 mA h g-1, suggesting that NiO-NiCo2O4 is a promising catalyst for Li-O2 batteries.

Achieving a High-Performance Carbon Anode through the P-O Bond for Lithium-Ion Batteries

Carbon materials with high initial Coulombic efficiency (ICE) and specific capacity in lithium-ion batteries are highly attractive. Herein, P-doped carbon has been prepared, and as an anode for lithium-ion batteries, it exhibits remarkably improved ICE and reversible capacity. P atoms are apt for the formation of the P-O bond in carbon with oxygen-containing groups. The doped P content strongly depends on the O content in carbon. The high-doped P content of 5.79 at. % can be obtained through changing the O content in carbon. Carbon with high contents of P and O displays high ICE and capacity as an anode for lithium-ion batteries. The P-O bond in carbon changes the morphology and composition of the solid electrolyte interface (SEI) layer and is beneficial to the formation of a thin and dense SEI layer. The P-O bond in carbon prevents the permeation and decomposition of solvated PF₆^- in the interior of the electrode during cycling, resulting in the improved ICE, reversible capacity, and rate capability. As an anode for lithium-ion batteries, the ICE can be improved to 70.9% for carbon with the P-O bond from 36.9% for carbon without the P-O bond. Carbon with the P-O bond displays high specific capacities of 566 mA h g^-1 after 100 cycles at 0.1 A g^-1 and 432 mA h g^-1 after 1000 cycles at 1 A g^-1. This design offers a simple and efficient method to improve the ICE and reversible capacity of hard carbon.