Acoustic actuation of fluids at small scales may finally enable a comprehensive lab-on-a-chip revolution in microfluidics, overcoming long-standing difficulties in fluid and particle manipulation on-chip. In this comprehensive review, we examine the fundamentals of piezoelectricity, piezoelectric materials, and transducers; revisit the basics of acoustofluidics; and give the reader a detailed look at recent technological advances and current scientific discussions in the discipline. Recent achievements are placed in the context of classic reports for the actuation of fluid and particles via acoustic waves, both within sessile drops and closed channels. Other aspects of micro/nano acoustofluidics are examined: atomization, translation, mixing, jetting, and particle manipulation in the context of sessile drops and fluid mixing and pumping, particle manipulation, and formation of droplets in the context of closed channels, plus the most recent results at the nanoscale. These achievements will enable applications across the disciplines of chemistry, biology, medicine, energy, manufacturing, and we suspect a number of others yet unimagined. Basic design concepts and illustrative applications are highlighted in each section, with an emphasis on lab-on-a-chip applications.

The sluggish redox kinetics of polysulfides and difficult oxidation process of Li2S severely hinder practical application of Li–S batteries under high sulfur loading and a low electrolyte dosage. To address these issues, we develop a bifunctional catalyst by manipulation of anion N doping in CoSe2 (N-CoSe2). Theoretical simulation results uncover that an introduced N element into CoSe2 could form a shorter Co–N bond, create a higher charge number of the Co central atom, bring new defect levels, and induce the Co 3d band closer to Fermi level. Further atomic level analysis revealed that N-CoSe2 could form shorter Co–S bonds with sulfur species and simultaneously weaken the S–S bridged bond of Li2S4 and Li–S bond of Li2S, which eventually facilitate the polysulfide conversion reaction in the discharge process and the Li2S oxidation in the charge process. With N-CoSe2 as a bifunctional catalyst, the battery exhibited a high areal capacity of 9.26 mAh g–1 under the low E/S (electrolyte/sulfur) ratio of 4.4 μL mg–1. Understanding the design concept of a bifunctional catalyst with anion doping would provide a new vision for realizing a high-performance Li–S battery.

The weak van der Waals interactions enable ion‐intercalation‐type hosts to be ideal pseudocapacitive materials for energy storage. Here, a methodology for the preparation of hydrated vanadium dioxide nanoribbon (HVO) with moderate transport pathways is proposed. Out of the ordinary, the intercalation pseudocapacitive reaction mechanism is discovered for HVO, which powers high‐rate capacitive charge storage compared with the battery‐type intercalation reaction. The main factor is that the defective crystalline structure provides suitable ambient spacing for rapidly accommodating and transporting cations. As a result, the HVO delivers a fast Zn2+ ion diffusion coefficient and a low Zn2+ diffusion barrier. The electrochemical results with intercalation pseudocapacitance demonstrate a high reversible capacity of 396 mAh g−1 at 0.05 A g−1, and even maintain 88 mAh g−1 at a high current density of 50 A g−1.

drastically superior specific energy density. [1][2][3][4][5][6][7] However, the successful implementation of Li-S batteries is still hindered by many challenges. One of the largest problems facing the current Li-S battery is the rapid capacity decay and serious selfdischarge caused by the dissolution and migration of intermediate lithium polysulfides (LiPSs). [8][9][10][11][12][13][14][15] Significant efforts have been dedicated to the research of suitable approach to address polysulfide shuttling. As one of the strategies, inserting an interlayer between the separator and sulfur electrode is widely applied due to the minimal changes to existing applications. [16][17][18][19] Various materials such as metal oxides, sulfides, and metal-organic frameworks have been proposed as functional interlayer to trap LiPSs through chemisorption, and this strategy has been demonstrated to be effective to block the migration of polysulfide species. [20][21][22][23][24] The interlayer serves as both adsorbent and current collector, where polysulfides can be reduced to insoluble products. [25,26] While this helps block LiPSs and improve the sulfur utilization, the produced Li 2 S is hard to oxidize back to soluble LiPSs due to the intrinsically poor electrical and ionic conductivity. [27] The accumulation of Li 2 S not only leads to the loss of active materials but also passivates the interlayer and impairs the electrochemical performance because of the insufficient transport of Li ions especially for cathodes with high sulfur loading. [1,16,[27][28][29] There is thereby an urgent need but it is still a significant challenge to develop interlayers that can not only block LiPSs but also accelerate Li 2 S oxidation on interlayers.To achieve this, we propose several key factors to consider when developing a practical bifunctional interlayer: 1) the adsorption energies between interlayer and LiPSs/Li 2 S that provides a strong anchoring; 2) the Li ion diffusion barrier that ensures good Li ion mobility; 3) the electrical conductivity of interlayer materials that facilitates electron transport and electrochemical conversions. In this work, we introduce MoN as a suitable interlayer material for Li-S batteries. On the one hand, the surface Mo atoms with unoccupied orbitals act as Lewis acid sites, and thus, MoN can serve as a good adsorbent for LiPSs. [30,31] On the other hand, our theoretical calculation reveals an extremely low Li ion diffusion barrier on MoN Rational design of effective polysulfide barriers is highly important for highperformance lithium-sulfur (Li-S) batteries. A variety of adsorbents have been applied as interlayers to alleviate the shuttle effect. Nevertheless, the unsuccessful oxidation of Li 2 S on interlayers leads to loss of active materials and blocks Li ion transport. In this work, a MoN-based interlayer sandwiched between the C-S cathode and the separator is developed. Such an interlayer not only strongly binds lithium polysulfides via Mo-S bonding but also efficiently accelerates the decomposition of Li 2...

The zinc (Zn)‐ion battery has attracted much attention due to its high safety and environmental protection. At present, the critical issues of the generation of dendrites and the accumulation of dead Zn on the surface will lead to a sharp decline of the battery life. Zn dendrites can be inhibited to some extent by constructing an interface protective coating. However, the existing rigid coating method cannot maintain conformal contact with Zn due to the volume change of Zn deposition and will cause fracture irreversibly during the cycle. Here, a highly self‐adaptable poly(dimethylsiloxane) (PDMS)/TiO2−x coating is developed that can dynamically adapt to volume changes and inhibit dendrites growth. PDMS has high dynamic and self‐adaptability due to the crosslinking of the B–O bond. In addition, the rapid and uniform transfer of Zn2+ is induced by the oxygen‐vacancy‐rich TiO2−x. The assembled cells still achieve 99.6% coulombic efficiency after 700 cycles at a current density of 10 mA cm−2. The adaptive interface coating constructed provides a sufficient guarantee for the stable operation of the Zn anode.

Aqueous zinc‐ion batteries (ZIBs) are an alternative energy storage system for large‐scale grid applications compared with lithium‐ion batteries, when the low cost, safety, and durability are taken into consideration. However, the reliability of the battery systems always suffers from the serious challenge of the large Zn dendrite formation and “dead Zn,” thus bringing out the inferior cycling stability, and even cell shorting. Herein, a dendrite‐free organic anode, perylene‐3,4,9,10‐tetracarboxylic diimide (PTCDI) polymerized on the surface of reduced graphene oxide (PTCDI/rGO) utilized in ZIBs is reported. Moreover, the theoretical calculations prove the reason for the low redox potential. Due to the protons and zinc ions coparticipant phase transfer mechanism and the high charge transfer capability, the PTCDI/rGO electrode provides superior rate capability (121 mA h g −1 at 5000 mA g −1 , retaining the 95% capacity of that compared with 50 mA g −1 ) and a long cycling life span (96% capacity retention after 1500 cycles at 3000 mA g −1 ). In addition, the proton coparticipation energy storage mechanism of active materials is elucidated by various ex‐situ methods.

Precisely tuning the coordination environment of the metal center and further maximizing the activity of transition metal–nitrogen carbon (M-NC) catalysts for high-performance lithium–sulfur batteries are greatly desired. Herein, we construct an Fe-NC material with uniform and stable Fe-N2 coordination structure. The theoretical and experimental results indicate that the unsaturated Fe-N2 center can act as a multifunctional site for anchoring lithium polysulfides (LiPSs), accelerating the redox conversion of LiPSs and reducing the reaction energy barrier of Li2S decomposition. Consequently, the batteries based on a porous carbon nitride supported Fe-N2 site (Fe-N2/CN) host exhibit excellent cycling performance with a capacity decay of 0.011% per cycle at 2 C after 2000 cycles. This work deepens the understanding of the relationship between electronic structure of M-NC sites and the catalysis effect for the conversion of LiPSs. This strategy also provides a potent guidance for the further application of M-NC materials in advanced lithium–sulfur batteries.

In this paper, a convenient approach based on the reaction between an alkyl thiol and hierarchical structured Cu(OH)2 substrates is reported for the fabrication of super-hydrophobic surfaces with controlled adhesion. This reaction can etch the Cu(OH)2 microstructures and simultaneously introduce a coating with low surface energy. By simply controlling the reaction time or the chain length of the thiol, super-hydrophobic surfaces with controlled adhesion can be achieved, and the adhesive force between the surface and the water droplet can be adjusted from extreme low (∼14 μN) to very high (∼65 μN). The tunable effect of the adhesion is ascribed to the different wetting states for the droplet on the surface that results from the change of the morphology and microstructure scale after the thiolate reaction. Noticeably, the as-prepared surfaces are acid/alkali-resisting; the acidic and basic water droplets have similar contact angles and adhesive forces to that of the neutral water droplet. Moreover, we demonstrate a proof of water droplet transportation for application in droplet-based microreactors via our surfaces. We believe that the results reported here would be helpful for the further understanding of the effect of wetting states on the surface adhesion and the fabrication principle for a super-hydrophobic surface with controlled adhesion.