Manipulating the Li-S reaction kinetics via the V8C7/phosphorus defect-integrated carbon promoter

2D-2D heterostructure of ionic liquid-exfoliated MoS2/MXene as lithium polysulfide barrier for Li-S batteries

Suppressing the dissolution and shuttling of lithium polysulfides (LiPSs) in electrolytes in lithium-sulfur batteries (LSBs) is the focus of researchers. Herein, functional liquid phase exfoliated MoS₂ and MXene (IL-MoS₂/MX) interlayer is proposed as the separator of LSBs. The unique alternating intercalation structure of the IL-MoS₂/MX interlayer provides a channel for ion transport while achieving uniform Li⁺ deposition on the anode side. Moreover, IL-MoS₂ achieves physical and chemical anchoring to LiPSs and lowers the energy barrier for battery reactions. As a result, the separator in the coin cell delivers an initial capacity of 764.4 mAh·g^-1 at 1C and high retention of 58.7 % after 700 cycles, with a decay only 0.059 % per cycle. Simultaneously, the excellent stability is also verified under varying current densities. Beyond that, ionic conductivity and lithium-ion migration number are adopted to confirm unique ion transport channels and uniform deposition of lithium. X-ray photoelectron spectroscopy, S₈ and Li₂S decomposition and nucleation energy barrier analysis are performed to verify the adsorption and catalytic conversion mechanisms. The convenient preparation and excellent performance of IL-MoS₂/MX provide a design strategy for functionalized interlayers for LSBs, and the possibility for commercialization.

Confine, Defect, and Interface Manipulation of Fe3 Se4 /3D Graphene Targeting Fast and Stable Potassium-Ion Storage

The fast electrochemical kinetics behavior and long cycling life have been the goals in developing anode materials for potassium ion batteries (PIBs). On account of high electron conductivity and theoretical capacity, transition metal selenides have been deemed as one of the promising anode materials for PIBs. Herein, a systematic structural manipulation strategy, pertaining to the confine of Fe₃ Se₄ particles by 3D graphene and the dual phosphorus (P) doping to the Fe₃ Se₄ /3DG (DP-Fe₃ Se₄ /3DG), has been proposed to fulfill the efficient potassium-ion (K-ion) evolution kinetics and thus boost the K-ion storage performance. The theoretical calculation results demonstrate that the well-designed dual P doping interface can effectively promote K-ion adsorption behavior and provide a low energy barrier for K-ion diffusion. The insertion-conversion and adsorption mechanism for multi potassium storage behavior in DP-Fe₃ Se₄ /3DG composite has been also deciphered by combining the in situ/ex situ X-ray diffraction and operando Raman spectra evidences. As expected, the DP-Fe₃ Se₄ /3DG anode exhibits superior rate capability (120.2 mA h g^-1 at 10 A g^-1 ) and outstanding cycling performance (157.9 mA h g^-1 after 1000 cycles at 5 A g^-1 ).