A Venus-flytrap-inspired pH-responsive porous membrane with internal crosslinking networks

A Venus-flytrap-inspired pH-responsive polybenzimidazole (PBI) porous membrane is designed and fabricated for flow battery application. In the design, PBI membranes with tunable pores are firstly created by introducing hydrophilic sulfonated poly(ether ether ketone) (SPEEK) into the casting solution. Then internal crosslinking networks are built on the pore walls by in situ acid-base reaction between PBI and SPEEK to improve membrane selectivity, while keeping high conductivity. The in situ acid-base reaction process closely resembles the trapping mechanism of the Venus flytrap plant, whose lobes close when they sense contact with an external force. Moreover, a vanadium flow battery (VFB) with the resultant membrane exhibits outstanding battery performance with a coulombic efficiency of 99.5% and an energy efficiency of 89.1% at a current density of 80 mA cm(-2), which are much higher than for commercial Nafion 115 (93.4%, 82.5%). Most importantly, a VFB with the prepared membrane keeps stable after continuously running for more than 10 000 cycles at a current density of 140 mA cm(-2), showing super-high stability. This work provides a simple and biomimetic strategy to fabricate membranes with high conductivity and stability

Solvent-Induced Rearrangement of Ion-Transport Channels: A Way to Create Advanced Porous Membranes for Vanadium Flow Batteries

Porous membranes with critically hydrophobic/hydrophilic phase-separated-like structures for use in vanadium flow battery application are first realized by solvent-induced reassembly of a polymer blend system. Porous poly(ether sulfone) (PES)/sufonated poly(ether ether ketone) (SPEEK) blend membranes with tunable pore size are prepared via the phase inversion method. After solidification, isopropanol (IPA) is introduced to induce the reassembly of sulfonated groups and further form ion-transport channels by using the interaction between IPA and functional groups in SPEEK. As a result, a highly phase separated membrane structure is created, composed of a highly stable hydrophobic porous PES matrix and hydrophilic interconnected small pores. The charged pore walls are highly beneficial to improving proton conductivity, while pores are simultaneously shrunk during the IPA treatment. Therefore, the resultant membranes show an excellent battery performance with a coulombic efficiency exceeding 99%, along with an energy efficiency over 91%, which is among the highest values ever reported. This article supplies an ease-to-operate and efficient method to create membranes with controlled ion-transport channels

Solvent-Induced Rearrangement of Ion-Transport Channels: A Way to Create Advanced Porous Membranes for Vanadium Flow Batteries

© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim Porous membranes with critically hydrophobic/hydrophilic phase-separated-like structures for use in vanadium flow battery application are first realized by solvent-induced reassembly of a polymer blend system. Porous poly(ether sulfone) (PES)/sufonated poly(ether ether ketone) (SPEEK) blend membranes with tunable pore size are prepared via the phase inversion method. After solidification, isopropanol (IPA) is introduced to induce the reassembly of sulfonated groups and further form ion-transport channels by using the interaction between IPA and functional groups in SPEEK. As a result, a highly phase separated membrane structure is created, composed of a highly stable hydrophobic porous PES matrix and hydrophilic interconnected small pores. The charged pore walls are highly beneficial to improving proton conductivity, while pores are simultaneously shrunk during the IPA treatment. Therefore, the resultant membranes show an excellent battery performance with a coulombic efficiency exceeding 99%, along with an energy efficiency over 91%, which is among the highest values ever reported. This article supplies an ease-to-operate and efficient method to create membranes with controlled ion-transport channels.status: publishe

Advanced Charged Sponge-​Like Membrane with Ultrahigh Stability and Selectivity for Vanadium Flow Batteries

© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Advanced charged sponge-like porous membranes with ultrahigh stability and selectivity are designed and fabricated for vanadium flow battery (VFB) applications. The designed porous membranes are fabricated via constructing positively charged cross-linked networks on the pore walls of polysulfone membranes. The charge density of the pore walls can be tuned by changing the crosslinking time. The positively charged pore walls can effectively retain vanadium ions via Donnan exclusion, hence keeping extremely high selectivity, while the crosslinked network effectively increases the membrane stability. As a result, the designed membranes exhibit an outstanding performance, combining extremely high selectivity and stability. The single cell assembled with the prepared porous membrane shows a columbic efficiency of 99% and an energy efficiency of 86% at a current density of 80 mA cm-2, which is much higher than Nafion 115 (93.5%; 82.3%). A battery assembled with the prepared membrane shows a stable battery performance over more than 6000 cycles, which is by far the longest record for porous membranes ever reported. These results indicate that advanced, charged, sponge-like, porous membranes with a crosslinked pore-wall structure are highly promising for VFB applications.status: publishe

A Highly Ion-Selective Zeolite Flake Layer on Porous Membranes for Flow Battery Applications

Zeolites are crystalline microporous aluminosilicates with periodic arrangements of cages and well-defined channels, which make them very suitable for separating ions of different sizes, and thus also for use in battery applications. Herein, an ultra-thin ZSM-35 zeolite flake was introduced onto a poly(ether sulfone) based porous membrane. The pore size of the zeolite (ca. 0.5nm) is intermediary between that of hydrated vanadium ions (>0.6nm) and protons (99% and an energy efficiency of >81% at 200mAcm(-2), which is by far the highest value ever reported. These convincing results indicate that zeolite-coated membranes are promising in battery applications

Sensors Anomaly Detection of Industrial Internet of Things Based on Isolated Forest Algorithm and Data Compression

Aiming at solving network delay caused by large chunks of data in industrial Internet of Things, a data compression algorithm based on edge computing is creatively put forward in this paper. The data collected by sensors need to be handled in advance and are then processed by different single packet quantity K and error threshold e for multiple groups of comparative experiments, which greatly reduces the amount of data transmission under the premise of ensuring the instantaneity and effectiveness of data. On the basis of compression processing, an outlier detection algorithm based on isolated forest is proposed, which can accurately identify the anomaly caused by gradual change and sudden change and control and adjust the action of equipment, in order to meet the control requirement. As is shown by experimental simulation, the isolated forest algorithm based on partition outperforms box graph and K-means clustering algorithm based on distance in anomaly detection, which verifies the feasibility and advantages of the former in data compression and detection accuracy