Nanoscale transition metal catalysts anchored on perovskite oxide enabling enhanced kinetics of lithium polysulfide redox in lithium-sulfur batteries

To obtain high-performance lithium-sulfur(Li-S)batteries,it is necessary to rationally design electrocatalytic materials that can promote efficient sulfur electrochemical reactions.Herein,the robust heterostructured material of nanoscale transition metal anchored on perovskite oxide was designed for efficient catalytic kinetics of the oxidation and reduction reactions of lithium polysulphide(Li PSs),and verified by density functional theory(DFT)calculations and experimental characterizations.Due to the strong interaction of nanoscale transition metals with Li PSs through chemical coupling,heterostructured materials(STO@M)(M=Fe,Ni,Cu)exhibit excellent catalytic activity for redox reactions of Li PSs.The bifunctional heterostructure material STO@Fe exhibits good rate performance and cycling stability as the cathode host,realizing a high-performance Li-S battery that can maintain stable cycling under rapid charge-discharge cycling.This study presents a novel approach to designing electrocatalytic materials for redox reactions of Li PSs,which promotes the development of fast charge-discharge Li-S batteries.

Enhancing electrochemical conversion of lithium polysulfide by 1T-rich MoSe_(2) nanosheets for high performance lithium-sulfur batteries

The sluggish conversion kinetics and shuttle effect of lithium polysulfides(LiPSs)severely hamper the commercialization of lithium-sulfur batteries.Numerous electrocatalysts have been used to address these issues,amongst which,transition metal dichalcogenides have shown excellent catalytic performance in the study of lithium-sulfur batteries.Note that dichalcogenides in different phases have different catalytic properties,and such catalytic materials in different phases have a prominent impact on the performance of lithium-sulfur batteries.Herein,1T-phase rich MoSe_(2)(T-MoSe_(2))nanosheets are synthesized and used to catalyze the conversion of LiPSs.Compared with the 2H-phase rich MoSe_(2)(H-MoSe_(2))nanosheets,the T-MoSe_(2) nanosheets significantly accelerate the liquid phase transformation of LiPSs and the nucleation process of Li2S.In-situ Raman and X-ray photoelectron spectroscopy(XPS)find that T-MoSe_(2) effectively captures LiPSs through the formation of Mo-S and Li-Se bonds,and simultaneously achieves fast catalytic conversion of LiPSs.The lithium-sulfur batteries with T-MoSe_(2) functionalized separators display a fantastic rate performance of 770.1 mAh/g at 3 C and wonderful cycling stability,with a capacity decay rate as low as 0.065%during 400 cycles at 1 C.This work offers a novel perspective for the rational design of selenide electrocatalysts in lithium-sulfur chemistry.

Constructing high coordination number of Ir-O-Ru bonds in IrRuO_(x)nanomeshes for highly stable acidic oxygen evolution reaction

IrRu bimetallic oxides are recognized as the promising acidic oxygen evolution reaction(OER)catalysts,but breaking the trade-off between their activity and stability is an unresolved question.Meanwhile,addressing the issues of mass transport obstruction of IrRu bimetallic oxides under high current remains a challenge for the development of proton exchange membrane water electrolysis(PEM-WE).Herein,we prepared an IrRuO_(x)nanomeshes(IrRuO_(x)NMs)with high coordination number(CN)of Ir-O-Ru bonds in a mixed molten salt with high solubility of the Ir/Ru precursor.X-ray absorption spectroscopy analysis revealed that the IrRuO_(x)NMs possess high coordination number of Ir-O-Ru bonds(CNIr-O-Ru=5.6)with a distance of 3.18Å.Moreover,the nanomesh structures of IrRuO_(x)NMs provided hierarchical channels to accelerate the transport of oxygen and water,thus further improving the electrochemical activity.Consequently,the IrRuO_(x)NMs as OER catalysts can simultaneously achieve high activity and stability with low overpotential of 196 mV to reach 10 mA·cm^(−2)and slightly increase by 70 mV over 650 h test.Differential electrochemical mass spectrometry tests suggest that the preferred OER mechanism for IrRuO_(x)NMs is the adsorbent evolution mechanism,which is beneficial for the robust structural stability.