Lithium (Li) metal is considered as the ultimate anode choice for developing next-generation high-energy batteries. However, the poor tolerance against moist air and the unstable solid electrolyte interphases (SEI) in...Lithium (Li) metal is considered as the ultimate anode choice for developing next-generation high-energy batteries. However, the poor tolerance against moist air and the unstable solid electrolyte interphases (SEI) induced by the intrinsic high reactivity of lithium bring series of obstacles such as the rigorous operating condition, the poor electrochemical performance, and safety anxiety of the cell, which to a large extent hinder the commercial utilization of Li metal anode. Here, an effective encapsulation strategy was reported via a facile drop-casting and a following heat-assisted cross-linking process. Benefiting from the inherent hydrophobicity and the compact micro-structure of the cross-linked poly(vinylidene-co-hex afluoropropylene) (PVDF–HFP), the as-encapsulated Li metal exhibited prominent stability toward moisture, as well corroborated by the evaluations both under the humid air at 25 °C with 30% relative humidity (RH) and pure water. Moreover, the encapsulated Li metal anode exhibits a decent electrochemical performance without substantially increasing the cell polarization due to the uniform and unblocked ion channels, which originally comes from the superior affinity of the PVDF–HFP polymer toward nonaqueous electrolyte. This work demonstrates a novel and valid encapsulation strategy for humiditysensitive alkali metal electrodes, aiming to pave the way for the large-scale and low-cost deployment of the alkali metal-based high-energy-density batteries.展开更多
It is a great challenge to prepare non-noble metal electrocatalysts toward hydrogen evolution reaction(HER)with large current density.Synergistic electronic and morphological structures of the catalyst have been consi...It is a great challenge to prepare non-noble metal electrocatalysts toward hydrogen evolution reaction(HER)with large current density.Synergistic electronic and morphological structures of the catalyst have been considered as an effective method to improve the catalytic performance,due to the enhanced intrinsic activity and enlarged accessible active sites.Herein,we present novel ternary Co_(1-x)V_(x)P nanoneedle arrays with modulated electronic and morphological structures as an electrocatalyst for highly efficient HER in alkaline solution.The NF@Co1-xVxP catalyst shows a remarkable catalytic ability with low overpotentials of 46 and 226 mV at current densities of 10 and 400 mA cm^(-2),respectively,as well as a small Tafel slope and superior stability.Combining the experimental and computational study,the excellent catalytic performance was attributed to the improved physical and chemical properties(conductivity and surface activity),large active surface area,and fast reaction kinetics.Furthermore,the assembled Co–V based electrolyzer(NF@Co_(1-x)V_(x)–HNNs(+)||NF@Co_(1-x)V_(x)P(-))delivers small full-cell voltages of 1.58,1.75,and 1.92 V at 10,100,and 300 mA cm^(-2),respectively.Our findings provide a systematic understanding on the V–incorporation strategy to promote highly efficient ternary electrocatalysts via synergistic control of morphology and electronic structures.展开更多
We report the gate-modulated Raman spectrum of defective graphene. We show that the intensity of the D peak can be reversibly tuned by applying a gate voltage. This effect is attributed to chemical functionalization o...We report the gate-modulated Raman spectrum of defective graphene. We show that the intensity of the D peak can be reversibly tuned by applying a gate voltage. This effect is attributed to chemical functionalization of the graphene crystal lattice, generated by an electrochemical reaction involving the water layer trapped at the interface between silicon and graphene.展开更多
基金This work was supported by National Key Research and Development Program(2016YFA0202500)National Natural Science Foundation of China(21776019)Beijing Natural Science Foundation(L182021).
文摘Lithium (Li) metal is considered as the ultimate anode choice for developing next-generation high-energy batteries. However, the poor tolerance against moist air and the unstable solid electrolyte interphases (SEI) induced by the intrinsic high reactivity of lithium bring series of obstacles such as the rigorous operating condition, the poor electrochemical performance, and safety anxiety of the cell, which to a large extent hinder the commercial utilization of Li metal anode. Here, an effective encapsulation strategy was reported via a facile drop-casting and a following heat-assisted cross-linking process. Benefiting from the inherent hydrophobicity and the compact micro-structure of the cross-linked poly(vinylidene-co-hex afluoropropylene) (PVDF–HFP), the as-encapsulated Li metal exhibited prominent stability toward moisture, as well corroborated by the evaluations both under the humid air at 25 °C with 30% relative humidity (RH) and pure water. Moreover, the encapsulated Li metal anode exhibits a decent electrochemical performance without substantially increasing the cell polarization due to the uniform and unblocked ion channels, which originally comes from the superior affinity of the PVDF–HFP polymer toward nonaqueous electrolyte. This work demonstrates a novel and valid encapsulation strategy for humiditysensitive alkali metal electrodes, aiming to pave the way for the large-scale and low-cost deployment of the alkali metal-based high-energy-density batteries.
基金the National Natural Science Foundation of China(21671096,21603094 and21905180)the Natural Science Foundation of Guangdong Province(2018B030322001 and 2018A030310225)+4 种基金Shenzhen Peacock Plan(KQTD2016022620054656)Shenzhen Key Laboratory Project(ZDSYS201603311013489)the Basic Research Project of the Science and Technology Innovation Commission of Shenzhen(JCYJ20190809115413414)the Science and Technology Development Fund from Macao SAR(FDCT–0102/2019/A2,FDCT–0035/2019/AGJ and FDCT–0154/2019/A3)the Multi-Year Research Grants(MYRG2017–00027–FST and MYRG2018–00003–IAPME)from the University of Macao。
文摘It is a great challenge to prepare non-noble metal electrocatalysts toward hydrogen evolution reaction(HER)with large current density.Synergistic electronic and morphological structures of the catalyst have been considered as an effective method to improve the catalytic performance,due to the enhanced intrinsic activity and enlarged accessible active sites.Herein,we present novel ternary Co_(1-x)V_(x)P nanoneedle arrays with modulated electronic and morphological structures as an electrocatalyst for highly efficient HER in alkaline solution.The NF@Co1-xVxP catalyst shows a remarkable catalytic ability with low overpotentials of 46 and 226 mV at current densities of 10 and 400 mA cm^(-2),respectively,as well as a small Tafel slope and superior stability.Combining the experimental and computational study,the excellent catalytic performance was attributed to the improved physical and chemical properties(conductivity and surface activity),large active surface area,and fast reaction kinetics.Furthermore,the assembled Co–V based electrolyzer(NF@Co_(1-x)V_(x)–HNNs(+)||NF@Co_(1-x)V_(x)P(-))delivers small full-cell voltages of 1.58,1.75,and 1.92 V at 10,100,and 300 mA cm^(-2),respectively.Our findings provide a systematic understanding on the V–incorporation strategy to promote highly efficient ternary electrocatalysts via synergistic control of morphology and electronic structures.
文摘We report the gate-modulated Raman spectrum of defective graphene. We show that the intensity of the D peak can be reversibly tuned by applying a gate voltage. This effect is attributed to chemical functionalization of the graphene crystal lattice, generated by an electrochemical reaction involving the water layer trapped at the interface between silicon and graphene.
