High Conductivity Phase Research Articles

High thermal conductive and photothermal phase change material microcapsules via cellulose nanocrystal stabilized Pickering emulsion for solar harvesting and thermal energy storage

Phase change materials (PCMs) are promising for thermal energy storage due to their high latent enthalpy and constant phase change temperature. However, organic PCMs suffer from leaking, low thermal conductivity, and flammability. Herein, high thermal conductivity, photothermal and flame-proof docosane microcapsules with melamine-formaldehyde (MF) and polypyrrole (PPy) (C22-CMFP) were reported with cellulose nanocrystal (CNC) stabilized Pickering emulsion droplets as templates through in-situ polymerization. CNCs showed outstanding C22 Pickering emulsifying ability with the presence of NaCl and provided ideal templates for C22 microcapsules. The obtained C22-CMFP microcapsules displayed high enthalpy (205.7 J/g), C22 core ratio (86.1 %), and stability. The C22-CMFP microcapsules retained an outstanding enthalpy remaining ratio (98.9 %) after 100 times cooling/heating cycles and could tolerate 100 °C for 12 h without leaking due to the robust hybrid CMFP shell. PPy significantly improved the thermal conductivity and photothermal conversion efficiency of C22-CMFP microcapsules. The C22-CMFP microcapsules exhibited a high thermal conductivity of 0.683 W/(m·K). The maximum temperature of C22-CMFP microcapsules under light irradiation for 18 min was 60.4 °C. Moreover, C22-CMFP microcapsules showed superb flame-proof properties. This study provides a facile approach to fabricate high enthalpy, stable, thermal conductive, photothermal, and flame-proof PCM microcapsules for solar harvesting and thermal energy storage.

Enhancing Li4Ti5O12 Anodes for High‐Performance Batteries: Ti3+ Induction via Plasma‐Enhanced Chemical Vapor Deposition and Dual Carbon/LLZO Coatings

AbstractLithium titanium oxide (LTO) is a promising anode material due to its ability to store lithium through intercalation reactions. However, its electrochemical performance is limited by poor electron conductivity and side reactions with the electrolyte. In this study, plasma‐enhanced chemical vapor deposition (PECVD) is employed to introduce oxygen vacancies and self‐doped Ti3+ into LTO to improve the internal conductivity. Subsequent carbon coating and aluminum‐doped lithium lanthanum zirconate garnet (LLZO) layers resulted in a multi‐layered composite denoted as LTO−L‐x. Morphological analyses using SEM and TEM demonstrated the successful growth of Al‐doped LLZO on carbon‐coated LTO. Aluminum ions in LLZO cubic structure are crucial for stabilizing the high ionic conductive phase during cooling, as confirmed by X‐ray diffraction. The dual coating layers have a significant impact on the rate capability, reducing polarization gaps and enabling higher capacities at various current rates. Long‐term cycling tests reveal the robustness of the composite, with LTO−L‐1.0 retaining 90.8 % capacity after 4000 cycles at 1.0 A g−1. This underscores the sustained high electronic and ionic conductivity facilitated by the dual coating layers. The study contributes to the design of advanced anode materials for lithium‐ion batteries, emphasizing the importance of tailored coating strategies to address conductivity and stability challenges.

Improving the Stability of 75Li2S·25P2S5 Glass-Ceramic Electrolytes Against Lithium Metals Through Li2O Doping

The chemical and electrochemical stability between solid-state electrolytes (SSEs) and lithium metals is one of the crucial factors in the performance of all-solid-state lithium batteries (ASSLBs). Doping modification has been shown to improve the ionic conductivity and air stability of SSEs, but further research is needed to demonstrate its effectiveness in enhancing stability with lithium metal. In this work, a series of Li2O-doped 75Li2S·25P2S5 glass-ceramic electrolytes have been successfully synthesized using ball milling method. Powder X-ray diffraction (pXRD) and 7Li magic angle spinning nuclear magnetic resonance (MAS NMR) spectroscopy results revealed that Li2O doping effectively reduced the percentage of residual Li2S in the ball milling stage and generated a high ionic conductivity phase Li7P3S11 during annealing. The electrolyte has the highest ionic conductivity (1.5 × 10−4 S cm−1 at room temperature) when doped with 1 mol% Li2O. Various electrochemical characterizations have shown that all doped electrolytes can effectively slow/suppress lithium dendrite formation while being chemically and electrochemically stable to some extent. Among these, 1 mol% Li2O-doped electrolyte performs the best, as the Li|1Li2O|Li cell maintains voltage and resistance nearly unchanged after 1000 h and 900 cycles, with no noticeable degradation in the material structure.

Mechanistic insight into the impact of dry-state prelithiated SiOx thin-film anode toward extremely fast-charging and long-term stability

Silicon suboxides (SiOx) have achieved partial success in commercialization as high-capacity anode materials to replace graphite because of optimal electrochemical properties over silicon. Unfortunately, the further development has been sluggish, jeopardizing the urgent need of green energy. The daunting challenges to tackle include low initial coulombic efficiency (ICE) and low charging rate due to poor electron and ionic conductivity. In the context of thin film microbattery, we propose to precisely control the chemical states of SiOx films through varying sputtering power followed by dry-state pre-lithiation through Li-metal thermal evaporation, superior to the current pre-lithiation approaches for SiOx thin-film anodes. We addressed the leading roles of the surface chemical states of the as-deposited SiOx in the formation of the high ionic conductive Li4SiO4 phase as the pre-solid electrolyte interphase during the proposed dry-state prelithiation process. Ultimately, the prelithiated SiOx successfully mitigated the most confronted issues as low ICE and C-rate limitation, achieving an unprecedented rate performance of 72.8 % at 20 C, and ultra-long-cycle retention of 54.2 % over 5000 cycles at 10 C. These results strongly prove that appropriate pre-lithiation provides tremendous advantages to SiOx thin film anode not only in prolonging electrode stability but also promoting a significant fast-cycling.

Smart Electrolytes for Lithium Batteries with Reversible Thermal Protection at High Temperatures

Battery safety is a multifaceted concern, with thermal runaway standing out as a primary issue. In this work, we introduce a novel temperature‐responsive, self‐protection electrolyte governed by the phase separation dynamics of poly (butyl methacrylate) (PBMA) in lithium salt/tetraglyme (G4) blends. This innovation effectively mitigates the risks associated with thermal runaway in lithium batteries. Our electrolyte exhibits a temperature‐responsive‐recovery characteristic, imparting intelligent capabilities to lithium batteries. At temperatures of >105oC, the electrolyte transitions from a homogeneous phase to a segregated state, comprising a PBMA‐rich phase with low conductivity and a high conductivity phase containing dissolved lithium salt in G4. The deposition of the PBMA‐rich phase on the electrode surface obstructs ion transport, thereby averting thermal runaway. Subsequently, upon returning to room temperature of 25oC, the electrolyte reverts to its homogeneous, highly conductive state, with battery capacity resuming at approximately 94%. Thus, our electrolyte offers robust, reversible, smart self‐protection for batteries. Additionally, it demonstrates exceptional cycling performance at room temperature. Our findings open new avenues for thermo‐reversible and self‐protective electrolytes, advancing the safe and widespread adoption of lithium‐ion batteries.

Phase change composites with ultra-high through-plane thermal conductivity achieved by vertically-aligned graphite film and double-shelled microcapsules

The heat dissipation in electronic devices has become bottleneck problem. One of the best solutions is to develop high performance materials which can not only dissipate the heat away, but also absorb heat energy. This kind of double function materials can be obtained by simultaneously using high thermal conductivity (TC) materials and phase change materials. The formation of continuous network of thermally conductive fillers is demonstrated as one of the most effective methods for fabricating highly thermally conductive composites. Here, graphite films (GF) are stacked and vertically cut to endow the composites with high through-plane TC. The obtained composites exhibit a through-plane TC of 51.55 W m−1 K−1 and a low thermal resistance of 0.398 °C cm2 W−1. Besides, double-shelled PDA@SiO2@paraffin (Pa) microcapsules are embedded into the composite to give its good heat-absorption capacity. Via a CPU thermal stress test, the composites demonstrate satisfactory temperature controlling performance.

Optimization design of a hybrid thermal runaway propagation mitigation system for power battery module using high-dimensional surrogate models

The demand for high energy density in lithium-ion battery packs for electric vehicles poses a challenge to maintaining its optimum operating temperature while reducing the risk of thermal runaway (TR) propagation. This study proposes a novel hybrid TR propagation mitigation system that balances heat transfer and thermal insulation requirements using low and high thermal conductivity phase change materials (PCM), heat pipes (HP), and air-cooling. The design and optimization of such a mitigation system are complex due to the many design parameters involved. The Adaptive-Kriging-High dimensional model representation (Adaptive-Kriging-HDMR) is used to establish a surrogate model of the system, and the sensitivity of the system's design parameters is evaluated with the maximum battery temperature and the system weight as the targets, thereby improving the efficiency of model calculation and reducing the dimension of optimization parameters. Then, the design of the sensitive parameters is optimized using an extended elitist non‐dominated sorting genetic algorithm (E-NSGA-II) multi-objective optimization algorithm. The results show that the modeling difficulty and optimization calculation time are significantly reduced by using a surrogate model. The calculation time for a single surrogate model only takes a few seconds instead of several hours for the original three-dimensional heat transfer and flow calculation. The thermal conductivity of high thermal conductivity-PCM, the distance between battery and low thermal conductivity-PCM, the battery spacing, and the HP length significantly affect the system. The optimized system substantially reduces the overall weight of the battery system while ensuring its good heat dissipation capability. In the case of TR in a single battery, the system succeeds in limiting the TR propagation to the same row, with the maximum battery temperature in the second row being only 64.3 °C, well below the battery TR trigger point. Under more severe conditions, such as TR occurring in two batteries simultaneously, the maximum battery temperature in the second row is 155.5 °C, and no TR spreads to the adjacent row. This study provides a rapid and effective method for designing a TR propagation mitigation system. It can serve as a reference for the engineering design and optimization of battery thermal management systems.

Investigation on the improvement method of ampacity for cable in duct bank: Using the mixed filler with high thermal conductivity material and phase change material

Duct laying is a common cable laying way for the case of not meeting excavation conditions. However, due to the slow air flow rate in the duct, the cable section laying the duct becomes one ampacity bottleneck. Backfilling the duct with the mixed filler of high thermal conductivity material and phase change material is an effective method to solve the problem. In this paper, the simulation models of cable in ducts with backfilling the mixed filler were used to analysis the effect of relative position of cable and duct on temperature distribution and guide the thermal modeling of external environment. Then, the thermal model of cable in duct was conducted and the layered method was adopted to optimize the model. The real cable experiment was designed to verify the accuracy of proposed model. The improvement effect of mixed filler with different thermal conductivity and phase transition region on the cable ampacity were discussed by using the proposed model. The investigations in this paper show that the use of mixed filler material can have a great contribution to ensure the safe operation of cable in duct.

Preparation and application of high thermal conductivity phase change microcapsules with fluorescence characteristics based on a ZnWO4 shell.

Phase change microcapsules (NePCMs) with high latent heat values, thermal conductivity and stability were synthesized by coating stearic acid (SA) phase change materials (PCMs) with zinc tungstate (ZnWO4) as the shell material. The prepared ZnWO4 and microcapsule samples are characterized through various techniques, and their thermophysical properties under different core-shell ratios and emulsifiers are compared. The highest value that the phase transition enthalpy reaches is 83.63 J g-1 when the core-shell ratio is 1 : 1 and sodium dodecylbenzenesulfonate (SDBS) is adopted as the emulsifier. Based on SEM and TEM results, the regular spherical shape and the complete core-shell structure of the microcapsule can be found, and the particle size ranges between 100 and 300 nm. The thermal conductivity of SA increased by 141.18%-238.43% after using ZnWO4 as the shell material. Moreover, thermogravimetric and leak-proof performance tests demonstrated that microcapsule samples possess high thermal stability. There was no leakage from the six microcapsule samples after heating, proving their potential application in thermal energy storage (TES) under long-term high-temperature conditions. In addition, the cost of ZnWO4 prepared by this method can be reduced by about 40%. According to UV absorption and fluorescence spectrum evaluation, ZnWO4 and microcapsule samples exhibit good photoluminescence and UV absorption properties, indicating that the sample can be widely employed in fluorescent construction, coatings and textile industries at a lower cost.

In-doped Li7La3Zr2O12 nanofibers enhances electrochemical properties and conductivity of PEO-based composite electrolyte in all-solid-state lithium battery

Garnet type Li7La3Zr2O12 solid electrolyte exhibits excellent thermal stability and high ionic conductivity, which is an ideal solid electrolyte. However, it is found that the cubic phase is a high conductivity phase and the synthesis condition is harsh. Therefore, low temperature synthesis and partial element substitution are expected to prepare cubic phase LLZO. In this paper, the LLZO cubic phase structure is stabilized by electrospinning technology and high-priced cation substitution strategy, and the transportation efficiency of lithium ions is improved. The experimental results show that LLZO NFs inorganic filler with stable cubic phase structure is obtained when the molar amount of In3+ is 0.2. The In3+ with large ion radius replaces the Li+ inside the crystal, effectively increases the lithium vacancy concentration, and increases the Li+ transport path inside the crystal, and successfully doubles the ionic conductivity of the composite solid electrolyte at 60 °C (9.39 × 10−4 S/cm). The lithium ions migration number and electrochemical window were increased to 0.19 and 5.2 V respectively. With excellent cycle performance (60 °C), it can cycle 2000 cycles at a high rate of 0.5 C charge and discharge, and the Coulomb efficiency has been close to 100 %. Li|PL-LILZO NFs (0.2)|LFP all-solid-state lithium batteries can light small bulbs at room temperature and have practical application prospects. Therefore, in the composite electrolyte, the increase of the lithium ions pathway inside the active inorganic filler crystal will also improve the comprehensive performance of the composite electrolyte for preparation.

Synthesis of low-cost Ti3AlC2-Ti2AlC dual MAX phase with high-electrical conductivity using economical raw materials and novel compositions

Titanium-aluminum-carbide (Ti3AlC2-Ti2AlC) dual MAX phases produced with mechanical alloying (MA) of raw materials followed by a self-propagating high-temperature synthesis (SHS) approach. The low-cost dual MAX phases have been manufactured from commercial powders of Ti, Al, TiC, and agricultural wastes-based activated carbon (AC). The effects of Ti/Al/C mole ratios and carbon sources with various prices on the surface morphology, microstructure, chemical structure, and electrical conductivity of dual MAX phases have been investigated. All synthesized MAX phases have acceptable surface morphology with hexagonal particles and high purity (78.87–99.26 %). The FESEM, EDS, XRD, and XPS analyses revealed that the AC and TiC are appropriate as carbon sources for the manufacture of Ti3AlC2-Ti2AlC dual and Ti3AlC2 single MAX phases, respectively. Moreover, the purity of the MAX phases can be controlled with Al/C ratios in raw materials composition. The AC-produced Ti3AlC2-Ti2AlC dual MAX phase with 3Ti:1.25Al:2 C displayed the highest electrical conductivity (5.631 ×106 S/m), while TiC-produced Ti3AlC2 single MAX phase with 3.25Ti:2.2Al:2 C composition has comparable electrical conductivity (2.203 ×106 S/m) and highest purity (99.26 %). This study makes available an advantageous method for low-cost synthesis of high-purity MAX phases. These understandings open up a pathway to improve synthesis protocols for low-cost and high-conductivity MAX phases in the future.

Tree-inspired and scalable high thermal conductivity ethylene–vinyl acetate copolymer/expanded graphite/paraffin wax phase change composites for efficient thermal management

Bioinspired fabrication of high thermal conductivity phase change composites has great prospects for efficient thermal management. However, the direct and partial imitations of nature are not facile to the full realization of natural systematic advantages and scalable production. Herein, inspired by the tree’s transportation system, this study adopted a bottom-up strategy to mimic the tree’s sophisticated hierarchy at both micro and bulk dimensions. The composites employed a phloem-mimic crosslinking ethylene–vinyl acetate copolymer/paraffin wax (EVA/PW) film as the intelligent heat storage and release medium, and the xylem-imitated roll-to-roll directional EVA/expanded graphite (EVA/EG) film with enhanced high thermal conductivity (51.1 W m−1 K−1 with the enhancement of 26,894 %) as fast heat conduction pathway. Above two components were assembled to develop phase change composites (PCCs) with annual-ring and multilayered structures. Both computational and experimental results revealed that the assembled tree-inspired structures significantly improve the heat conduction performances of PCCs. The tree-inspired PCCs showed significantly high thermal conductivity (7.01 W m−1 K−1 with the enhancement of 2821 %) with a low filler content (9.0 vol%). Meanwhile, obtained PCCs with high phase change enthalpy exhibited excellent temperature regulation performance. This work offers a promising route for the scalable manufacture of advanced PCCs for efficient thermal management, and a general strategy to realize the natural systematic advantages via the bottom-up strategy.

High thermal conductive and anti-leakage composite phase change material with halloysite nanotube for battery thermal management system

The thermal safety of battery module is demonstrated as the main bottleneck to hinder wider adoption of electric vehicles (EVs). It is vital to explore efficient thermal management system to satisfy the rapidly increasing need for EVs. Composite change materials (CPCMs) as passive cooling system has greatly potential application in battery packs. However, the inherent leakage and low thermal conductivity are restricted its widely utilized in practical applications. In this study, the high thermal conductivity CPCM with PEG/EG/HNT@AP has successfully prepared through a synergistic method of in situ chemical reduction and physical blending technology. Polyethylene glycol (PEG) as the phase change matrix and halloysite nanotube (HNT) as the support material can provide cross-linked network to prevent its leakage. Especially, the expanded graphite (EG) and silver nanoparticles (AgNPs) assembled into HNT (HNT@AP) play a synergistic role to construct an interconnected thermal network. The results indicates that the thermal conductivity is increased to 1.15 W·m−1·K−1 and the latent heat of phase change can maintain to 103.65 J·g−1, when the content of HNT@AP is 40 %. In addition, the battery module with PEG/EG/HNT@AP and PEG/EG/ER are designed and measured during charge and discharge cycling process, respectively. It reveals that battery module with PEG/EG/HNT@AP can exhibit excellent thermal management effect, which temperature was controlled below 60 °C at 3C discharge rate even under 35 °C ambient temperature. Therefore, this work sheds light on rational design of high thermal conductive composite material to improve thermal safety of battery pack in the EVs.

Цифровая осциллография полимерных мембран с протонной проводимостью

Polyvinyl alcohol-based cast membranes have promising application in creating commonly available fuel cells and fuel synthesizers, as well as inexpensive water sources and microelectromechanical systems. In order to control the properties of such membranes a deep understanding of the charge transfer mechanisms and their relationship with the structure formed at a certain composition and manufacturing technology is required. A method for studying the structure of the proton-conductive polymer membranes using digital oscillography of ion currents excited by the low-frequency rectangular pulses with the amplitudes below the threshold voltage of the ionic conductivity in a dehydrated membrane, and for the analysis of the resulting ion current pulses (spikes) in the frames of the model of a proton pump acting in each layer of the membrane is proposed in this paper. Fast Fourier transform of these oscillograms reveals from 2 to 4 branches or spike sequences corresponding to the phases with different ionic conductivity and makes it possible to determine the thicknesses of both high-conductivity phase layers (7–30 µm) and low-conductivity phase interlayers (1–7 µm) formed in the process of polymerization. The reason of spike merging into bursts is described in terms of successively induced increase in the excited proton density over a threshold value in highly conductive layers. The resonance observed in dry proton membranes at the frequencies of about 2.2 to 3.0 kHz is interpreted as the burst merge point with the further increase in impedance due to proton lagging and respective decrease in the effective thickness of active layers. The effective charge carrier concentrations (as small as 1012 to 1013 cm−3) and the velocity (from 5 to 18 cm/s for the highly conductive phases which turned out to be much higher than those observed in solutions) are estimated. The asymmetry of the cast membranes, which becomes apparent at low frequencies and causes the generation of a direct ion current in response to excitation by a purely alternating current, is studied. It is found that the apparent conductivity determining contribution to the total ohmic resistance is made by a thin interlayer with a very low ion velocity, presumably surface layer, rather than the main layers. The conclusion on the optimization of the production technology and the composition of the proton membranes for various applications is made.

A Review of Subsurface Electrical Conductivity Anomalies in Magnetotelluric Imaging.

After 70 years of development, magnetotelluric (MT), a remote sensing technique for subsurface electrical resistivity imaging, has been widely applied in resource exploration and the deep tectonic evolution of the Earth. The electrical resistivity anomalies and their quantitative interpretation are closely related to or even controlled by the interconnected high-conductivity phases, which are frequently associated with tectonic activity. Based on representative electrical resistivity studies mainly of the deep crust and mantle, we reviewed principal electrical conduction mechanisms, generally used conductivity mixing models, and potential causes of high-conductivity including the saline fluid, partial melting, graphite, sulfide, and hydrogen in nominally anhydrous minerals, and the general methods to infer the water content of the upper mantle through electrical anomaly revealed by MT.

Cover Feature: On‐Surface‐Assembled Single‐Layer Metal‐Organic Frameworks with Extended Conjugation (ChemPlusChem 5/2023)

The cover feature image shows the construction of single-layer metal-organic frameworks with extended conjugation (SL-cMOFs) by on-surface coordination assembly. SL-cMOFs exhibit electronic bands that lead to high conductivity or non-trivial quantum phases. On-surface coordination assembly, in which molecular linkers and metal atoms assemble on atomic flat substrates via in-plane coordination, offers a unique approach for preparing SL-cMOFs. Experimental characterizations of the geometries and conjugated band structures of SL-cMOFs have been achieved by surface techniques such as scanning tunneling microscopy and spectroscopy. More information can be found in the Review by Jing Liu and Nian Lin.

Improved air-stability and conductivity in the 75Li2S·25P2S5 solid-state electrolyte system: the role of Li7P3S11.

Doping modification is regarded as a simple and effective method for increasing the ionic conductivity and air stability of solid state electrolytes. In this work, a series of (100-x)(0.75Li2S·0.25P2S5)·xP2O5 (mol%) (x = 0, 1, 2, 3 and 4) glass-ceramic electrolytes were synthesized by a two-step ball milling technique. Various characterization techniques (including powder X-ray diffraction, Raman and solid-state nuclear magnetic resonance) have proved that the addition of P2O5 can stimulate 75Li2S·25P2S5 system to generate the high ionic conductivity phase Li7P3S11. Through the doping optimization strategy, 98(0.75Li2S·0.25P2S5)·2P2O5 glass-ceramic (2PO) not only had a 3.6 times higher ionic conductivity than the undoped sample but also had higher air stability. Its ionic conductivity remained in the same order of magnitude after 10 minutes in the air. We further investigated the reasons why 2PO has a relatively high air stability using powder X-ray diffraction and scanning electron microscopy in terms of crystal structure degradation and morphology changes. In comparison to the undoped sample, the high ionic conductivity phases (β-Li3PS4 and Li7P3S11) of 2PO were better preserved, and less impurity and unknown peaks were generated over a short period of exposure time. In addition, the morphology of 2PO only changed slightly after 10 minutes of exposure. Despite the fact that the particles aggregated significantly after several days of exposure, 2PO tended to form a protective layer composed of S8, which might allow some particles to be shielded from attack by moisture, slowing down the decay of material properties.

Reversible and high-contrast thermal conductivity switching in a flexible covalent organic framework possessing negative Poisson's ratio.

The ability to dynamically and reversibly control thermal transport in solid-state systems can redefine and propel a plethora of technologies including thermal switches, diodes, and rectifiers. Current material systems, however, do not possess the swift and large changes in thermal conductivity required for such practical applications. For instance, stimuli responsive materials, that can reversibly switch between a high thermal conductivity state and a low thermal conductivity state, are mostly limited to thermal switching ratios in the range of 1.5 to 4. Here, we demonstrate reversible thermal conductivity switching with an unprecedented 18× change in thermal transport in a highly flexible covalent organic framework with revolving imine bonds. The pedal motion of the imine bonds is capable of reversible transformations of the framework from an expanded (low thermal conductivity) to a contracted (high thermal conductivity) phase, which can be triggered through external stimuli such as exposure to guest adsorption and desorption or mechanical strain. We also show that the dynamic imine linkages endow the material with a negative Poisson's ratio, thus marking a regime of materials design that combines low densities with exceptional thermal and mechanical properties.

On-Surface-Assembled Single-Layer Metal-Organic Frameworks with Extended Conjugation.

Single-layer metal-organic frameworks with extended conjugation (SL-cMOFs) exhibit electronic bands that lead to high conductivity or non-trivial quantum phases. Experimental realization of SL-cMOFs has been demonstrated using on-surface coordination self-assembly. The tunability and adaptability of coordination assembly offers rich opportunities for designing and fabricating SL-cMOFs with various geometric characteristics. In this Review, we discuss the recent experimental advances in on-surface synthesis of SL-cMOFs and characterization of their band structures. Special attention has been paid to the MOFs featuring Kagome lattices. Starting from the general principles of their structural design, the SL-cMOFs recently achieved via on-surface coordination self-assembly are subsequently divided into three categories, that is, M3 L2 , M2 L3 , and M3 L MOFs (M for metal and L for ligand), and the corresponding works are overviewed. The current challenges and prospective directions are also discussed.

Impact of Na Concentration on the Phase Transition Behavior and H- Conductivities in the Ba-Li-Na-H-O Oxyhydride System.

K2 NiF4 -type Ba-Li oxyhydride (BLHO) transitions to a so-called hydride superionic conductor, exhibiting a high and essentially temperature-independent hydride ion (H- ) conductivity over 0.01 Scm-1 through the disordering of H- vacancies above 300 °C. In this study, a Ba-Li-Na-H-O oxyhydride system synthesized in which lithium is partially substituted with sodium in BLHO and investigated the effects of Na content on the phase transition behavior and the conductivity. Structural refinements and differential scanning calorimetry experiments confirmed a lowering trend in the phase transition temperatures and decreasing enthalpy changes for the transition with increasing Na content. Substitution of not <40% of Li with Na lowered the degree of ordered vacancies at the H- sites at room temperature and improved conductivities by more than two orders of magnitude in the low-temperature region (T < 300 °C) before the phase transition. These findings clearly show that introducing Na into the lattice effectively stabilizes the high-conductive phase of BLHO.