Nano self-assembly of fluorophosphate cathode induced by surface energy evolution towards high-rate and stable sodium-ion batteries

In the field of materials science and engineering,controlling over shape and crystal orientation remains a tremendous challenge.Herein,we realize a nano self-assembly morphology adjustment of Na3V2(PO4)2F3(NVPF)material,based on surface energy evolution by partially replacing V3+with aliovalent Mn2+.Crystal growth direction and surface energy evolution,main factors in inducing the nano self-assembly of NVPF with different shapes and sizes,are revealed by high-resolution transmission electron microscope combined with density functional theory.Furthermore,NVPF with a two-dimensional nanosheet structure(NVPF-NS)exhibits the best rate capability with 68 mAh·g−1 of specific capacity at an ultrahigh rate of 20 C and cycle stability with 80.7%of capacity retention over 1,000 cycles at 1 C.More significantly,when matched with Se@reduced graphene oxide(rGO)anode,NVPF-NS//Se@rGO sodium-ion full cells display a remarkable long-term stability with a high capacity retention of 93.8%after 500 cycles at 0.5 C and−25°C.Consequently,experimental and theoretical calculation results manifest that NVPF-NS demonstrates such superior performances,which can be mainly due to its inherent crystal structure and preferential orientation growth of{001}facets.This work will promise insights into developing novel architectural design strategies for high-performance cathode materials in advanced sodium-ion batteries.

A self-crosslinking,double-functional group modified bacterial cellulose gel used for antibacterial and healing of infected wound

Cellulose/chitosan composite,as a mature commercial antibacterial dressing,is an important type of wound repair material.However,how to achieve the perfect compound of two components and improve antibacterial activity is a major,lingering issue.In this study,a bifunctional group modified bacterial cellulose(DCBC)was prepared by carboxymethylation and selective oxidation.Further,the chitosan(CS)was compounded in the network of DCBC by self-crosslinking to form dialdehyde carboxymethyl bacterial cellulose/chitosan composites(S-DCBC/CS).The aldehyde group can react with amino of CS by Schiff base reaction.The carboxyl group of DCBC and the amorphous distribution of CS molecular chains increase the antimicrobial properties of com-posites.The bacteriostatic rate of composites could be higher than 95%.Bacteria can be attracted onto the surface of composites,what we call it“directional adhesion antibacterial effects”.In particular,a kind of large animal wound model,deep II degree infected scald of Bama miniature pig,was used to research the antimicrobial and healing properties of materials.The S-DCBC/CS can effectively inhibit bacterial proliferation of wound and kill the bacteria.The wound healing rate of S-DCBC/CS was up to 80%after three weeks.The composites show better antibacterial and promoting concrescence effects than traditional chitosan dressings.

Quasi-Grotthuss mechanism in a nonporous sulphate

The transportation of the proton,the smallest ion in nature,is rudimentary in chemical and biological reactions[1,2],such as photosynthesis[3],enzyme catalysis[4],and Brensted acid/base reactions[5],and currently even imperative in some devices,namely proton exchange membrane fuel cells(PEMFCs)[6,7].The processes of these elementary reactions,like proton transfer,appear to be astonishingly analogous.