Ion diffusion kinetics,depending on the size,tortuosity,connectivity of the channels,greatly affects the rate performance of the electrodes.Two-dimensional materials(2DMs) has emerged as promising electrode materials ...Ion diffusion kinetics,depending on the size,tortuosity,connectivity of the channels,greatly affects the rate performance of the electrodes.Two-dimensional materials(2DMs) has emerged as promising electrode materials in the past decades.Howeve r,the applications of 2DMs electrodes are limited by the strong restacking problem,which leads to a poor rate capability.In this work,we for the first time mediated the mo rphology of molybdenum disulfide(MoS_(2)) nanosheets via a facile coagulation method;abundant sheet crumples were induced,which greatly enhance their surface accessibility and thus benefit the ion diffusion kinetics.Consequently,the crumpled-MoS_(2) electrodes follow a capacitive Na-ion charge-storage mechanism to a large extent.Importantly,we demonstrate the special role of organic cations in the inter-sheet assembly configuration,in sharp contrast with that of alkali/alkaline-earth ones.We propose that organic cations cause edge/face contact of the sheets,instead of the face/face contact,thus affording a house-of-cards structure.展开更多
The nano-Si/graphite nanocomposites are the promising anodes candidates for high-energy lithium-ion batteries because of their high theoretical capacities and low volume variations.However,the nano-Si has a severe ten...The nano-Si/graphite nanocomposites are the promising anodes candidates for high-energy lithium-ion batteries because of their high theoretical capacities and low volume variations.However,the nano-Si has a severe tendency to separate from the graphite substrate due to the inherently weak bonding between them,thus leading to the deteriorated cycling performance and low Coulombic efficiency.Herein,we design a robust nano-Si/graphite nanocomposite structure with strong interfacial adhesion caused by the Si—Ti and Ti—C covalent bonds.The abundant Si—Ti and Ti—C bonds formed between nano-Si and graphite greatly enhance the interfacial adhesion force,resulting in the highly stabilized and integrated electrode structure during battery cycling.Consequently,the as-obtained nano-Si/graphite anodes deliver a high capacity retention of 90.0% after 420 cycles at 0.5 C with an average Coulombic efficiency of 99.5%;moreover,a high initial Coulombic efficiency of 90.2% is achieved.Significantly,this work provides a novel strategy to address the poor interfacial adhesion between nano-Si and graphite,which can be applied to other nano-Si based composites anodes.展开更多
Graphene oxide(GO)is widely used in the construction and application of various 2 D membrane-based materials due to its unique colloidal structure.Herein,we demonstrate that micrometer-sized particles can make up free...Graphene oxide(GO)is widely used in the construction and application of various 2 D membrane-based materials due to its unique colloidal structure.Herein,we demonstrate that micrometer-sized particles can make up freestanding membranes enabled by the extraordinary amphiphilic and polymer-like properties of graphene oxide through freeze casting.The 2 D macromolecule,GO could well wrap the particles for better uniformity and stability in either dispersion or membrane.Importantly,freeze casting plays an important role in avoiding the severe aggregation of micrometer-sized particles in the solventremoving process.After reduction,the membrane exhibits good electrical conductivity while maintaining its integral structure,which can be directly used as a freestanding binder-free electrode.This work provides a universal approach to fabricate freestanding membranes with various micrometersized materials for energy storage.展开更多
基金supported by the National Natural Science Foundation of China (Nos.21938005 and 21905206)。
文摘Ion diffusion kinetics,depending on the size,tortuosity,connectivity of the channels,greatly affects the rate performance of the electrodes.Two-dimensional materials(2DMs) has emerged as promising electrode materials in the past decades.Howeve r,the applications of 2DMs electrodes are limited by the strong restacking problem,which leads to a poor rate capability.In this work,we for the first time mediated the mo rphology of molybdenum disulfide(MoS_(2)) nanosheets via a facile coagulation method;abundant sheet crumples were induced,which greatly enhance their surface accessibility and thus benefit the ion diffusion kinetics.Consequently,the crumpled-MoS_(2) electrodes follow a capacitive Na-ion charge-storage mechanism to a large extent.Importantly,we demonstrate the special role of organic cations in the inter-sheet assembly configuration,in sharp contrast with that of alkali/alkaline-earth ones.We propose that organic cations cause edge/face contact of the sheets,instead of the face/face contact,thus affording a house-of-cards structure.
基金supported by grants from the Fundamental Research Funds for the Central Universities (No.300102319308)the National Natural Science Foundation of China (No.21905206)+1 种基金the Shanghai Sail Program (No.19YF1450800)the Natural Science Foundation of Shanghai (No.19ZR1424600)。
文摘The nano-Si/graphite nanocomposites are the promising anodes candidates for high-energy lithium-ion batteries because of their high theoretical capacities and low volume variations.However,the nano-Si has a severe tendency to separate from the graphite substrate due to the inherently weak bonding between them,thus leading to the deteriorated cycling performance and low Coulombic efficiency.Herein,we design a robust nano-Si/graphite nanocomposite structure with strong interfacial adhesion caused by the Si—Ti and Ti—C covalent bonds.The abundant Si—Ti and Ti—C bonds formed between nano-Si and graphite greatly enhance the interfacial adhesion force,resulting in the highly stabilized and integrated electrode structure during battery cycling.Consequently,the as-obtained nano-Si/graphite anodes deliver a high capacity retention of 90.0% after 420 cycles at 0.5 C with an average Coulombic efficiency of 99.5%;moreover,a high initial Coulombic efficiency of 90.2% is achieved.Significantly,this work provides a novel strategy to address the poor interfacial adhesion between nano-Si and graphite,which can be applied to other nano-Si based composites anodes.
文摘Graphene oxide(GO)is widely used in the construction and application of various 2 D membrane-based materials due to its unique colloidal structure.Herein,we demonstrate that micrometer-sized particles can make up freestanding membranes enabled by the extraordinary amphiphilic and polymer-like properties of graphene oxide through freeze casting.The 2 D macromolecule,GO could well wrap the particles for better uniformity and stability in either dispersion or membrane.Importantly,freeze casting plays an important role in avoiding the severe aggregation of micrometer-sized particles in the solventremoving process.After reduction,the membrane exhibits good electrical conductivity while maintaining its integral structure,which can be directly used as a freestanding binder-free electrode.This work provides a universal approach to fabricate freestanding membranes with various micrometersized materials for energy storage.