CoSe nanoparticles in-situ grown in 3D honeycomb carbon for high-performance lithium storage

Although transition metal selenides are considered to be extremely promising anode materials for lithium-ion batteries (LIBs), severe volume changes and low electronic conductivity are their huge and unavoidable challenges. To solve these problems, CoSe nanoparticles in-situ grown on the inner surface of every macropore of 3D honeycomb C is successfully synthesized by three simple steps: dense assembling of polystyrene spheres, calcination and gaseous selenylation. The sizes of CoSe and honeycomb pores are 10-15 nm and 190 nm, respectively. The content of CoSe is 72 wt%. This unique architecture guarantees high electrochemical activity, rapid reaction kinetics and excellent structural stability of CoSe, as identified by cycling and rate performance measurements, various electrochemical kinetics analyses and ex-situ characterization of the cycled electrode material. As a result, the CoSe@honeycomb C anode exhibits extraordinary cycling performance (823.5 mAh g-1 after 200 cycles at 0.5 A g-1, 610.1 mAh g-1 after 250 cycles at 2 A g-1, 247 mAh g-1 after 1500 cycles at 5 A g-1) and exceptional rate capability (261.9 mAh g-1 at 10 A g-1, 1491.4 mAh g-1 at 0.1 A g-1), demonstrating that it is a potential anode material for high-performance LIBs.The authors gratefully acknowledge the support from Natural Science Foundation of Zhejiang Province, China (No. LY21E020011, LY21F040008), major project of Changshan Research Institute, Zhejiang Sci-Tech University (22020237-J), and the National Scholarship Fund of China Scholarship Council

Shaping characteristics of excavation contours in sequential controlled fracture blasting of rock-anchored beams in Shuangjiangkou underground powerhouse

Abstract Influences of high in-situ stress generally need to be considered when excavating deep underground caverns. The dynamic fracture behaviors of rocks under blast loads were investigated by using the rock-anchored beam excavation in underground powerhouses of Shuangjiangkou Hydropower Station in Sichuan Province, China as the engineering background. To solve the problems of the poor blasting breakage effect of rocks and the difficulty in protecting surrounding rocks during excavation, mechanical properties of granite under static and dynamic loads were investigated and the sequential controlled fracture blasting (SCFB) method was adopted during in-situ tests. Based on the Riedel-Hiermaier-Thoma constitutive model and the strength criterion, software LS-DYNA was employed to simulate the dynamic propagation of blasting-induced cracks. The contour shaping effect obtained via numerical simulation is generally consistent with the test results. The results show that SCFB can to some extent control the direction of crack initiation and rock fracture behavior of the blasthole wall cracks and the spacing of successive bursting holes is about 10 times the diameter of the blastholes when the cracks between the blastholes are shaped the best effect. Moreover, the magnitude and direction of principal in-situ stress can both affect the propagation path and length of blasting-induced cracks. The results of the research on the excavation and construction of deeply buried underground caverns have a certain reference value

Self-assembly of a nano hydrogel colloidal array for the sensing of humidity.

Traditional artificial opals are assembled from silica or polystylene colloidals which have poor swellability and a lower response to stimuli. A novel three-dimensional photonic crystal array sensor which has a high stability and desired structural colour was fabricated from the self assembly of nano hydrogel colloids. The nano hydrogel colloids were prepared by co-polymerisation of N-isopropylacrylamide, functional monomer acrylic acid and N-tert-butylacrylamide. The relative humidity from 20% to 100% could be detected rapidly via the reflection spectrum of the nano hydrogel colloidal array with a maximum amount of red shift of 24 nm. The response kinetics for humidity of the nano hydrogel colloidal array were investigated, and correspondingly, a rational response mechanism of the compactness of the close-packed structure caused by the swelling of the nano hydrogel colloidal array was discussed. The nano hydrogel colloidal array sensor presented good reversibility and can be reused for at least five rounds

Self-assembly of a nano hydrogel colloidal array for the sensing of humidity

Traditional artificial opals are assembled from silica or polystylene colloidals which have poor swellability and a lower response to stimuli. A novel three-dimensional photonic crystal array sensor which has a high stability and desired structural colour was fabricated from the self assembly of nano hydrogel colloids. The nano hydrogel colloids were prepared by co-polymerisation of N-isopropylacrylamide, functional monomer acrylic acid and N-tert-butylacrylamide. The relative humidity from 20% to 100% could be detected rapidly via the reflection spectrum of the nano hydrogel colloidal array with a maximum amount of red shift of 24 nm. The response kinetics for humidity of the nano hydrogel colloidal array were investigated, and correspondingly, a rational response mechanism of the compactness of the close-packed structure caused by the swelling of the nano hydrogel colloidal array was discussed. The nano hydrogel colloidal array sensor presented good reversibility and can be reused for at least five rounds

Hierarchical Confinement Effect with Zincophilic and Spatial Traps Stabilized Zn-Based Aqueous Battery

Zn-based aqueous batteries (ZABs) have been regarded as promising candidates for safe and large-scale energy storage in the "post-Li" era. However, kinetics and stability problems of Zn capture cannot be concomitantly regulated, especially at high rates and loadings. Herein, a hierarchical confinement strategy is proposed to design zincophilic and spatial traps through a host of porous Co-embedded carbon cages (denoted as CoCC). The zincophilic Co sites act as preferred nucleation sites with low nucleation barriers (within 0.5 mA h cm-2), and the carbon cage can further spatially confine Zn deposition (within 5.0 mA h cm-2). Theoretical simulations and in situ/ex situ structural observations reveal the hierarchical spatial confinement by the elaborated all-in-one network (within 12 mA h cm-2). Consequently, the elaborate strategy enables a dendrite-free behavior with excellent kinetics (low overpotential of ca. 65 mV at a high rate of 20 mA cm-2) and stable cycle life (over 800 cycles), pushing forward the next-generation high-performance ZABs.This research work’s funding was supported by the National Key R&D Program of China (2018YFE0201701 and 2018YFA0209401), National Natural Science Foundation of China (NSFC Grants 52103308 and 22109029), High Impact Project funded by Qatar University (QUHI-CAS-21/22-1), Natural Science Foundation of Jiangsu Province (Grant BK20210826), Natural Science Foundation of Shanghai (22ZR1403600), Fudan University (JIH2203010 and IDH2203008/003), Postdoctoral Science Foundation of China (2021M690658), Talent Development Funding Project of Shanghai (2021030), and Lvyang Jinfeng Plan for Excellent Doctor of Yangzhou City

A solid-to-solid metallic conversion electrochemistry toward 91% zinc utilization for sustainable aqueous batteries

The diffusion-limited aggregation (DLA) of metal ion (Mn+) during the repeated solid-to-liquid (StoL) plating and liquid-to-solid (LtoS) stripping processes intensifies fatal dendrite growth of the metallic anodes. Here, we report a new solid-to-solid (StoS) conversion electrochemistry to inhibit dendrites and improve the utilization ratio of metals. In this StoS strategy, reversible conversion reactions between sparingly soluble carbonates (Zn or Cu) and their corresponding metals have been identified at the electrode/electrolyte interface. Molecular dynamics simulations confirm the superiority of the StoS process with accelerated anion transport, which eliminates the DLA and dendrites in the conventional LtoS/StoL processes. As proof of concept, 2ZnCO3·3Zn(OH)2 exhibits a high zinc utilization of ca. 95.7% in the asymmetry cell and 91.3% in a 2ZnCO3·3Zn(OH)2 || Ni-based full cell with 80% capacity retention over 2000 cycles. Furthermore, the designed 1-Ah pouch cell device can operate stably with 500 cycles, delivering a satisfactory total energy density of 135 Wh kg-1.Published versionThis work was financially supported by the National Natural Science Foundation of China (52102261; 22109029), Natural Science Foundation of Jiangsu Province (BK20210942), Natural Science Foundation of Shanghai (22ZR1403600), Natural Science Foundation of the Jiangsu Higher Education Institutions of China (20KJB150007), and Changzhou Science and Technology Young Talents Promotion Project (KYZ21005). D.C. thanks the financial support from Fudan University (nos. JIH2203010 and IDH2203008/003)

Protocol in evaluating capacity of Zn–Mn aqueous batteries: a clue of pH

In the literature, Zn–Mn aqueous batteries (ZMABs) confront abnormal capacity behavior, such as capacity fluctuation and diverse “unprecedented performances.” Because of the electrolyte additive-induced complexes, various charge/discharge behaviors associated with different mechanisms are being reported. However, the current performance assessment remains unregulated, and only the electrode or the electrolyte is considered. The lack of a comprehensive and impartial performance evaluation protocol for ZMABs hinders forward research and commercialization. Here, a pH clue (proton-coupled reaction) to understand different mechanisms is proposed and the capacity contribution is normalized. Then, a series of performance metrics, including rated capacity (Cr) and electrolyte contribution ratio from Mn2+ (CfM), are systematically discussed based on diverse energy storage mechanisms. The relationship between Mn (II) ↔ Mn (III) ↔ Mn (IV) conversion chemistry and protons consumption/production is well-established. Finally, the concrete design concepts of a tunable H+/Zn2+/Mn2+ storage system for customized application scenarios, opening the door for the next-generation high-safety and reliable energy storage system, are proposed.Ministry of Education (MOE)The authors sincerely acknowledge financial support from the National Natural Science Foundation of China (NSFC grant nos. 21571080, 22109029, and 22279023), Natural Science Foundation of Shanghai (22ZR1403600), International Center of Future Science, Jilin University, Changchun, P. R. China (ICFS Seed Funding for Young Researchers), and the Singapore Ministry of Education by Academic Research Fund Tier 2 (MOE-T2EP50121-0006)

Tandem Chemistry with Janus Mesopores Accelerator for Efficient Aqueous Batteries

A reliable solid electrolyte interphase (SEI) on the metallic Zn anode is imperative for stable Zn-based aqueous batteries. However, the incompatible Zn-ion reduction processes, scilicet simultaneous adsorption (capture) and desolvation (repulsion) of Zn2+(H2O)6, raise kinetics and stability challenges for the design of SEI. Here, we demonstrate a tandem chemistry strategy to decouple and accelerate the concurrent adsorption and desolvation processes of the Zn2+ cluster at the inner Helmholtz layer. An electrochemically assembled perforative mesopore SiO2 interphase with tandem hydrophilic −OH and hydrophobic −F groups serves as a Janus mesopores accelerator to boost a fast and stable Zn2+ reduction reaction. Combining in situ electrochemical digital holography, molecular dynamics simulations, and spectroscopic characterizations reveals that −OH groups capture Zn2+ clusters from the bulk electrolyte and then −F groups repulse coordinated H2O molecules in the solvation shell to achieve the tandem ion reduction process. The resultant symmetric batteries exhibit reversible cycles over 8000 and 2000 h under high current densities of 4 and 10 mA cm–2, respectively. The feasibility of the tandem chemistry is further evidenced in both Zn//VO2 and Zn//I2 batteries, and it might be universal to other aqueous metal-ion batteries