Amorphous Se species anchored into enclosed carbon skeleton bridged by chemical bonding toward advanced K-Se batteries

Potassium-selenium(K-Se)batteries have attracted significant attention as one of the most promising alternatives of lithium-ion storage systems owing to high energy density and low cost.In the design of Se-based cathode materials,however,the low utilization rate of active Se and the rapid dissolution of polyselenides seriously weaken the capacity and cycle stability.Therefore,how to make full use of Se species without loss during the charge and discharge process is the key to design high-performance Se-based cathode.In this paper,a 3 D"water cube"-like Se/C hybrid(denoted as Se-O-PCS)is constructed with the assistance of Na_(2)CO_(3) templates.Thanks to the abundant carbonate groups(CO_(3)^(2-))originated from the Na_(2)CO_(3) templates,the molten Se species are firmly anchored into the pore of carbon skeleton by strong C-O-Se bonding.Thus,this unique Se-O-PCS model not only improves the utilization of active Se species,but also can reduce the contact with the electrolyte to inhibit the shuttle effect of polyselenides.Moreover,flexible carbon skeleton gives Se-O-PCS hybrid a good electrical conductivity and excellent structural robustness.Consequently,the resultant Se-O-PCS hybrid is endowed with an obviously enhanced K-ions storage property.

Fc-empowered exosomes with superior epithelial layer transmission and lung distribution ability for pulmonary vaccination

Mucosal vaccines offer potential benefits over parenteral vaccines for they can trigger both systemic immune protection and immune responses at the predominant sites of pathogen infection.However,the defense function of mucosal barrier remains a challenge for vaccines to overcome.Here,we show that surface modification of exosomes with the fragment crystallizable(Fc)part from IgG can deliver the receptor-binding domain(RBD)of SARS-CoV-2 to cross mucosal epithelial layer and permeate into peripheral lung through neonatal Fc receptor(FcRn)mediated transcytosis.The exosomes F-L-R-Exo are generated by genetically engineered dendritic cells,in which a fusion protein Fc-Lamp2b-RBD is expressed and anchored on the membrane.After intratracheally administration,F-L-R-Exo is able to induce a high level of RBD-specific IgG and IgA antibodies in the animals’lungs.Furthermore,potent Th1 immune-biased T cell responses were also observed in both systemic and mucosal immune responses.F-L-R-Exo can protect the mice from SARS-CoV-2 pseudovirus infection after a challenge.These findings hold great promise for the development of a novel respiratory mucosal vaccine approach.

VLS和VSS生长机制调控的单层TMD中的反向掺杂分布

掺杂是改善过渡金属二硫族化合物(TMD)单层薄膜性能的重要方法.然而,现有的研究大多集中在掺杂能力上,对掺杂分布的研究还处于起步阶段.近年来,基于旋涂化学气相沉积法研究了掺杂原子空间掺杂分布的差异.这些掺杂的TMD大多是通过气-液-固(VLS)生长机制生长的.采用气-固-固(VSS)生长机制生长的TMD尚未被用来深入研究掺杂分布.本文采用Na_(2)WO_(4),NaVO_(3),NaOH(Na-Pre),(NH_(4))_(2)WO_(4),NH_(4)VO_(3)(NH_(4)-Pre)等前驱体合成V–WS_(2).观察到中心和边缘区域完全相反的掺杂分布.还观察到浓度变化较大的界面的出现.通过透射电子显微镜精确地表征了掺杂原子的空间浓度.根据密度泛函理论的计算结果,掺杂分布的差异是由初始态引起的,这与VLS和VSS的生长机制有关.这项工作为控制掺杂原子的分布提供了一种新的方法,对掺杂TMD在微电子和纳米电子器件中的应用具有重要意义.

Realizing the Long Lifespan of Molybdenum Trioxide in Aqueous Aluminum Ion Batteries Through Potential Regulation

MoO_(3) is one of the most promising anode materials for aqueous aluminum batteries due to its high theoretical capacity and suitable aluminum insertion/de-insertion potential.However,the inferior cycling stability limits its further application,and the failure mechanism is still unclear.In this article,we provide a straightforward potential regulation technique to manage phase evolution during the charge/discharge process,which ultimately results in a markedly enhanced MoO_(3) electrode cycling stability.The failure mechanism study reveals that the excessive oxidation of the electrode during charge/discharge generates the H_(0.34)MoO_(3) phase,which has high solubility and is the primary cause of MoO_(3) deactivation.Although the dissolved Mo species will be deposited onto the electrode sheet again,the deposition is not electrochemically active and cannot contribute to the capacitance.Controlling the cutoff potential prevented the production of H_(0.34)MoO_(3),resulting in excellent cycling performance(80.1% capacity retention after 4000 cycles).The as-assembled α-MoO_(3)//MnO_(2) full battery exhibits high discharge plateaus(1.4 and 0.9 V),large specific capacity(200 mAhg^(-1) at 2 Ag^(-1)),and ultra-high coulombic efficiency(99%).The research presented here may contribute to the development of highly stable electrode materials for aqueous batteries.

Dual carbon Li-ion capacitor with high energy density and ultralong cycling life at a wide voltage window

Using the same materials for the cathode and anode in energy storage devices could greatly simplify the technological process and reduce the device cost significantly.In this paper,we assemble a dual carbon-based Li-ion capacitor with the active materials derived entirely from a single precursor,petroleum coke.For the anode,petroleum cokederived carbon(PCC)is prepared by simple ball milling and carbonization,having a massive tap density(1.80 g cm^(-3))and high electrical conductivity(11.5 S cm^(-1)).For the cathode,the raw petroleum coke is activated by KOH(petroleum cokeactivated carbon(PC-AC)sample)to achieve a well-developed pore structure to meet a rapid capacitive behavior.As a result,in addition to the robust structural stability of both the anode and cathode,the assembled dual carbon Li-ion capacitor shows a high energy density(231 W h kg^(-1)/206 W h L^(-1))and ultralong cycling life(up to 3000/10,000 cycles)at a wide voltage window.The excellent electrochemical response and simple production process make the PCC materials have great potential for practical application.

High-performance aluminum-polyaniline battery based on the interaction between aluminum ion and-NH groups

Aluminum-ion batteries(AIBs)are a type of promising energy storage device due to their high capacity,high charge transfer efficiency,low cost,and high safety.However,the most investigated graphitic and metal dichalcogenide cathodes normally possess only a moderate capacity and a relatively low cycling stability,respectively,which limit the further development of high-performance AIBs.Here,based on the results of first principles calculations,we developed a polyaniline/graphene oxide composite that exhibited outstanding performances as a cathode material in AIBs(delivering 180 mA h g^−1 after 4000 cycles),considering both the discharge capacity and the cycling performance.Ex-situ characterizations verified that the charge storage mechanism of polyaniline depended on the moderate interactions between−NH in the polyaniline chain and the electrolyte anions,such as AlCl4^−.These findings lay the foundation of the development of high-performance AIBs based on conducting polymers.