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Highlights • Porous carbon sheet is prepared through the reaction of NaBH 4 and NaHCO 3 at high temperature under inert atmosphere. • In-situ generated CO 2 is used as the carbon source and reduced into solid carbon materials by NaBH 4. • The obtained porous carbon sheet shows excellent electrochemical performances. Abstract Porous carbon sheet (PCS) was prepared by reduction reaction between NaBH 4 and the in-situ formed CO 2 gas from the thermal-decomposition of NaHCO 3 under inert atmosphere. During this preparation process, NaHCO 3 also could be used as the activation agent and increases the specific surface area of carbon materials. The obtained PCS has a specific surface area of 828 m2/g. At a current density of 0.5 A/g, the specific capacitance of the PCS electrode is 201 F/g. Furthermore, the PCS electrode exhibits excellent rate capability (80% capacitance retention at 15 A/g) and superior cycling stability. These results suggest a facile and environmental benign method to prepare economical and high quality porous carbon sheet materials for energy storage applications. [ABSTRACT FROM AUTHOR]

A composite material for phosphoric acid (PA) loaded membrane was prepared using a porous polytetrafluoroethylene (PTFE) thin film. N, N-Dimethylhexadecylamine partially quaternized poly (vinyl benzyl chloride) (qPVBzCl − ) was synthesized as the substrate for the phosphoric acid loaded polymer membrane. SEM observation indicated that the pores were filled with the qPVBzCl − . The maximum PA loading level was calculated to be 4.67–5.12 per repeat unit on average. TGA results showed that resultant composite membrane was stable in the intermediate temperature from 100 °C to 200 °C. The composite membrane tensile stress was 56.23 MPa, and the Young's Modulus was 0.25 GPa, and the fractured elongation was 23%. The conductivity of the composite membrane after the PA addition (H 3 PO 4 @PTFE/qPVBzCl − ) increased from 0.085 S cm −1 to 0.11 S cm −1 from 105 °C to 180 °C. The peak power density of the H 2 /O 2 at 175 °C under low humidity condition (<1%) for H 3 PO 4 @PTFE/qPVBzCl − membranes was 360 mW cm −2 . [ABSTRACT FROM AUTHOR]

Abstract: A strategy to improve the alkaline exchange membrane tensile strength was introduced based on porous PTFE and quaternized polyvinyl benzyl chloride (qPVBz/OH−). A thin PTFE film was used as the support to prepare the composite AAEM to improve the mechanical strength. Tensile stress tests showed 51.1 MPa which was twice that of the pure anion exchange membrane qPVBz/OH−. SEM observations showed that the pores of the PTFE were successfully filled with qPVBz/OH− polymer and there was no structure defects in the cross-section of the resultant membrane. The synthesized composite membrane had very good thermal stability. The through plane ionic conductivity was in the range of 1.65 × 10−2 to 2.2 × 10−2 S cm−1 in the temperature range of 25 °C–60 °C. The power density of H2 and O2 fuel cell gave 162 mW cm−2. [Copyright &y& Elsevier]

Abstract: This work reported an alkaline anion exchange membrane water electrolyser (AAEMWE) without noble metal as the catalyst. Methylated melamine grafted poly vinyl benzyl chloride (mm-qPVBz/Cl−) was synthesized and cast as the membrane. The conductivity of this hydroxide ion exchange membrane increased from 1.6 × 10−2 S cm−1 to 2.7 × 10−2 S cm−1 when the temperature was increased from 25 °C to 60 °C. Membranes were examined using TEM. The oxygen evolution catalyst used was based on Cu0.7Co2.3O4 particle 20–30 nm in size, synthesized through a thermal decomposition method. A membrane electrode assembly was prepared with the resultant membrane as electrolyte, the Cu0.7Co2.3O4 nano-particles as the anode catalyst and Ni nano-powders as the hydrogen evolution catalyst. SEM observations showed that the catalysts were well dispersed on the electrodes. The polarization curves exhibited onset voltages for water electrolysis of around 1.5 V. The MEA polarisation in deionised water exhibited voltages of 2.19 V, 2.05 V, 1.99 V at a current density of 100 mA cm−2 at temperatures of 25 °C, 40 °C and 55 °C respectively. [Copyright &y& Elsevier]

Abstract: An alkaline anion exchange membrane has been developed from poly (methyl vinyl ether-alt-maleic anhydride) (PMVMA) by grafting quaternary ammonium groups through a maleic anhydride ring-open reaction. FT-IR spectra showed successful grafting of quaternary ammonium groups on this cheap raw material. TGA showed that the degradation temperature was 150°C which was due to the loss of the quaternary ammonium groups. The tensile stress of the resultant membrane after ion exchange was 9.0MPa, and the Young''s modulus was 0.14GPa with a fractured elongation 11%. The through plane, anion conductivity varied from 1.9×10−2 to 2.7×10−2 Scm−2 in the temperature range of 25–65°C. The power density of a fuel cell with the membrane increased with the operation temperature in the range from 15°C to 35°C. With an ionomer loading of 15% in membrane electrode assemblies (MEA), the power density in the fuel cell was 115mWcm−2 and 40mWcm−2 for O2 (35°C) and air (30°C), respectively. [Copyright &y& Elsevier]

Abstract: A novel method to prepare poly (ethylene oxide)/graphene oxide (PEO/GO) composite membrane aimed for the low temperature polymer electrolyte membrane fuel cells without any chemical modification is presented in this work. The membrane thickness is 80μm with a GO content of 0.5wt%. And SEM images show the PEO/GO membrane is condensed composite material without structure defects. Small angle XRD results for the membrane samples show that the d-spacing reflection (001) of GO in PEO matrix is shifted from 2θ =11° to 4.5° as the PEO molecules intercalated into the GO layers during the membrane preparation process. FTIR tests show the typical –COOH vibration near 1700cm−1. Tensile tests show the resultant PEO/GO membrane tensile strength of 52.22MPa and Young''s modulus 3.21GPa, and the fractured elongation was about 5%. The ionic conductivity of this PEO/GO membrane increases from 0.086 to 0.134Scm−1 when the operation temperature increases from 25 to 60°C with 100% relative humidity. And further tests show the DC electronic resistance of this membrane is higher than 20MΩ at room temperature with 100% relative humidity. Polarization curves in a single cell with this membrane give a maximum power density of 53mWcm−2 at the operation temperature around 60°C, without optimizing the catalyst layer composition. [Copyright &y& Elsevier]

Owing to the widespread application of lithium-ion batteries (LIBs), various operating conditions pose significant challenges to battery safety. Developing precise and prompt warning strategies is crucial for preventing LIB safety issues in different application scenarios. Herein, the effects of charge rate (C-rate), ambient temperature (A-temp), preload force (P-force), and initial state of charge (I-SOC) on multidimensional signal evolution are comprehensively investigated based on the orthogonal design method. The time sequences of the expansion force, voltage, gas concentration, and temperature during the overcharge abuse tests were discussed in detail, and the quantification of the SOC boundary for these signals was emphasized. Overall, the expansion force is the earliest abnormal signal, which is minimally influenced by the four factors under various operating conditions, and can be used as a warning indicator before venting. During the overcharging process, the SOC boundary corresponding to abnormal expansion force (F abn), temperature (T abn), internal short circuit (ISC), and thermal runaway (TR) are within ranges of 106.38–110.92 %, 110.50–164.76 %, 123.17–187.86 %, and 125.71–165.18 %, respectively, which are mainly affected by the C-rate. However, the venting SOC boundary ranging from 111.96 % to 119.45 % is predominantly influenced by A-temp. Additionally, the abnormal voltage (U abn) SOC boundary ranging from 111.45 % to 117.38 % shows a relatively consistent influence from the four factors. Based on this, a three-level safety warning strategy with a corresponding response action applicable to various operating conditions was proposed under the guidance of multidimensional signal fusion. This study provides essential safety guidance for the wider application of LIBs, contributing to the resolution of storage and utilization issues associated with renewable energy. • Reveal four characteristic signal evolution under various influencing factors. • Expansion force displays abnormality earliest under multiple operating conditions. • Safety boundary parameters are evaluated quantitatively using range analysis method. • Develop a battery venting detection method based on temperature signal. • Propose three-level warning strategies for multiple application scenarios. [ABSTRACT FROM AUTHOR]

Solid-state electrolyte batteries are considered as one of the promising next generation power sources. A novel cross-linked nanocomposite polymer electrolyte (CNPE) based on poly (propylene oxide)-poly (ethylene oxide)-poly (propylene oxide) triblock main chains and surface-modified SiO 2 nanoparticles are prepared to establish a super flexible and stable polymer framework. The CNPE exhibits high ionic conductivity of 1.32 mS cm−1 at 20 °C and its electrochemical stability window reaches up to 6.5 V (versus Li+/Li). The favorable Li deposition behavior provided by CNPE films is identified by the stripping/plating test at a current density of 2.4 mA cm−2 for 1700 h. The CNPE films possess excellent mechanical stability (highly stretchable with ultimate elongation of 700%). Li/CNPE/LiFePO 4 batteries deliver an initial discharge capacity of 160 mAh g−1 at 0.2 C, which is 94.1% of the theoretic capacity, and maintain the high specific capacity of 148 mAh g−1 at 0.5 C. This work provides a new approach toward designing high performance electrolyte for lithium metal batteries. Image 1 • This hybrid polymer electrolyte combines the advantages of the hydrogen bonding system and nanocomposite framework. • The electrolyte membranes exhibit excellent mechanical stability and super flexibility. • The Li/Li symmetric cells with this electrolyte display remarkable Li stripping/plating behavior. • The LiFePO 4 /Li cells with this electrolyte exhibit superior rate performance and cycling stability. [ABSTRACT FROM AUTHOR]

Prismatic and pouch configurations are two distinct packaging formats for lithium-ion batteries, with significant differences in failure behavior. However, the effect of packaging formats on cell-level thermal runaway and its propagation at the module-level has not been thoroughly understood, especially from the perspective of multidimensional signal evolution. In this study, a comparative analysis of the failure behaviors in prismatic and pouch batteries is conducted under various thermal abuse scenarios, at both the cell and module levels. This study examines a range of multidimensional signals, simultaneously including expansion force, gas concentration, gas temperature, battery temperature, and voltage. Our findings reveal four distinct peaks in the expansion force of the prismatic cell, in contrast to only two for pouch cells. Both cell types display a consistent venting voltage of approximately 3.35 V, with gas emissions detected after venting. Notably, the venting force and temperature of the prismatic cell reach up to 5577 N and 121.2 °C, respectively, which are approximately 3000 N and 57.0 °C higher than those of the pouch cell. Especially, the abnormal rise rate in expansion force at 5 N/s emerges as the earliest detectable signal among the four signals regardless of the packaging formats, offering a lead time of over 80 s before venting occurs, and 444 s prior to the onset of thermal runaway at both cell and module levels. Additionally, a temperature rise rate exceeding 0.2 °C/s is a critical signal for an impending TR event. This study deepens the understanding of failure mechanisms unique to different battery packaging formats and guides early safety warning design for energy storage applications. • Effect of packaging formats on multidimensional signal evolution is revealed. • Force characteristic peaks during thermal runaway are compared for two types of cells. • Significant differences in gas temperatures for the packing formats are analyzed. • Force anomaly can be detected earliest for cells and modules with both packing forms. • Force signal is more suitable as an early warning indicator in prismatic cells. [ABSTRACT FROM AUTHOR]

Prismatic and pouch packaging formats are commonly used in LiNi x Co y Mn z O 2 (NCM) batteries for electric vehicles, each showing distinct failure dynamics. However, a comprehensive study is lacking on how these packaging types affect thermal runaway (TR) at the cell level and its propagation at the module level, with a particular gap in understanding the dynamics of multidimensional signals. In this study, we experimentally explore the effect of cell format on 40 Ah NCM523 prismatic and pouch battery failure behaviors under overcharging and overheating conditions, by applying multidimensional signals, including the swelling force, gas, voltage, and temperature of the batteries. Results indicate that both types of batteries exhibit similar time scales for the failure modes when overcharged. In contrast, under overheating conditions, the pouch batteries fail significantly earlier than the prismatic batteries, including abnormal swelling, venting, gas emission, internal short circuit, and TR. Additionally, the prismatic batteries can withstand a swelling force of 5000 N at venting, while it is 2000 N for the pouch batteries. During TR, the prismatic batteries present a maximum temperature increase rate below 100 K/s, while the pouch batteries exhibit one over 200 K/s. Furthermore, the pouch batteries generally display more severe TR hazards and faster TR propagation than the prismatic cells. This study enhances the comprehension of TR and TR propagation mechanisms across different cell formats, providing crucial insights for the safety design and early warning strategies of battery modules. • Multidimensional signals are employed to investigate the battery failure process. • Overcharging and overheating are used to trigger thermal runaway (TR). • Force increase rate is utilized to detect the battery's early abnormal swelling. • The evolution sequence of five different gases is unveiled during the TR process. • Pouch and prismatic cells are compared to study the effect of packaging formats. [ABSTRACT FROM AUTHOR]

Cathode materials significantly affect the failure behavior of lithium-ion batteries, but there is a lack of comparative research on the multidimensional signal evolution for batteries with various cathode materials when subjected to thermal runaway (TR). This study investigates the effect of cathode materials on battery safety properties by conducting overheating and overcharging abuse experiments on LiNi x Co y Mn (1-x-y) O 2 (NCM 523, 622, and 811) as well as LiFePO 4 (LFP) batteries. The multidimensional signals, including expansion force, gas concentrations, temperature, and voltage, are comprehensively and quantitatively analyzed. The results demonstrate that expansion force shows the earliest anomalies regardless of the cathode material in both abuse conditions. Gas can be detected after venting, followed by significant anomalies in voltage and temperature. Additionally, under overheating conditions, LFP cells exhibit the longest TR warning time of 677 s. However, the force anomaly-based warning method is more suitable for low-nickel NCM cells under overcharging scenarios. Specifically, NCM 523 cells achieve an overcharging warning time of 992 s at temperatures as low as 42.9 °C, and hold the highest venting force of 9859 N and venting temperature at 114.1 °C. On this basis, a hierarchical warning strategy based on multidimensional signal fusion is proposed. This study provides valuable insights into TR early warning and safety management in LIBs with different cathode materials. • Effects of cathode materials on battery failure behaviors are evaluated. • Multidimensional signal evolution, particularly expansion force, is revealed. • LFP cells exhibit the best superiority to overheating with the longest warning time. • NCM 523 cells show the best endurance to overcharging with the longest warning time. • A hierarchical warning strategy based on multidimensional signal fusion is proposed. [ABSTRACT FROM AUTHOR]

Thermal runaway introduces a significant challenge in the widespread application of lithium-ion batteries, necessitating advanced early-warning technologies to ensure safety, particularly during charging. Only monitoring the temperature and voltage limit the performance of diagnostic algorithms. The expansion behavior of batteries, which is linked to their operating status, offers a vital indicator of safety. In this study, the evolution of multidimensional signals during overcharging experiments at different current rates is comprehensively investigated. The result shows that the abnormal expansion force can be detected at temperatures as low as 35.4 °C, which achieves an early warning signal 11 min earlier than the onset of battery thermal runaway. The effect of charging rate on battery safety is comprehensively analyzed, showing that the time interval between the warning signal of the expansion force and temperature increases steadily from 151 s to 682 s as the charging rate decreases. However, the charging rate hardly affects the stage of charge boundary of venting, which is around ±118 %. These insights are crucial for understanding early warning mechanisms in overcharged batteries, offering valuable guidance for enhancing the safety of electric vehicles and energy storage systems. • Force signal offers early warning 682 s before battery thermal runaway. • Abnormal expansion force can be detected at a minimum temperature of 35.4 °C. • Effect of charging rate on battery safety is comprehensively analyzed. • Charging rate hardly affects stage of charge boundary of venting. • Force signal can be utilized as an overcharge warning indicator at high rates. [ABSTRACT FROM AUTHOR]

The characteristics of thermal runaway in batteries exhibit significant differences depending on their states of charge (SOCs), posing considerable challenges in accurate and timely warning for thermal runaway accidents. This paper conducts an experimental investigation into the external expansion force, voltage, and temperature behaviours of batteries under different SOCs under thermal abuse scenarios. The expansion force signal was found first to exhibit abnormal characteristics (with an indicator value of 5 N/s), offering an earlier warning signal >642 s prior to thermal runaway, when the battery back temperature is merely approximately 318.15 K. To analyse the main causes of abnormal expansion, ultrasonic nondestructive tests were performed and suggested that a higher SOC intensify the side reactions and cause gas generation inside batteries. Notably, compared to normal-charged batteries (0% ≤ SOC ≤ 100%), over-charged batteries (SOC > 100%) are more sensitive to expansion force than normal-charged batteries. Furthermore, compared with voltage and temperature signals, the early warning time of the expansion force rises with the increase in the SOC of an overcharged battery, in contrast to normal-charged batteries. Finally, a novel hazard classification safety warning strategy for battery failure is effectively proposed. These novel findings hold substantial practical implications for creating more accurate early warning systems for battery thermal runaway, enhancing the safe and reliable operation of battery systems. • Effect of SOC on multidimensional signal evolution is comprehensively revealed. • Expansion force can serve as an early warning signal of battery failure. • Expansion force evolution of batteries with different states of charge is revealed. • Nondestructive tests are conducted to analyse the main causes of abnormal expansion. • A novel warning strategy with hazard classification for battery failure is proposed. [ABSTRACT FROM AUTHOR]

LiNi x Co y Mn 1-x-y O 2 (NCM) is one of the most critical cathode materials for high energy density lithium-ion batteries in electric vehicle applications. Nevertheless, capacity degradation and long-term cycle instability due to the aging of cathode/electrolyte interfaces remain significant challenges for NCM materials. Various surface stabilization techniques, including doping and coating, can be employed for NCM modifications. Traditionally, new coating materials are identified by chemical intuition or trial-and-error synthesis, which hinders the discovery speed of high-performance coating materials. A novel neural network model named Attention Graph Convolutional Neural Network (ACGNet) has been developed to predict crystals' electrochemical stability windows from atom and bonding features and exhibits remarkable predictive performance with a mean absolute error of 0.586 V. Then, the developed model is utilized to conduct high-throughput screening of 13,943 candidate compounds for their coating potential. Among the candidates, LiPO 3 exhibits prominent potential as a coating material due to its high oxidation voltage and low preparation cost. The subsequent battery assembly experiment and electrochemical characterization reveal that the incorporation of LiPO 3 significantly enhances the cycle stability of NCM batteries. In summary, our model exhibits exceptional accuracy in predicting material properties and serves as a compelling example for machine learning applications in battery materials. [Display omitted] [ABSTRACT FROM AUTHOR]

Graphene quantum dot (GQD) has been attractive in analytical science field due to its low toxicity, stable photoluminescence. Herein, nitrogen-doped GQD (N-GQD) was prepared by a facile solvothermal treatment of GO using dimethylformamide, and exhibited a green emission with 23.1% quantum yield. The N-GQD probe showed a selective and sensitive fluorescence enhancement response to Al 3+ , the mechanism might be the formation of a complex between Al 3+ and N-GQD constrained the photo-induced electron transfer (PET) process of N-GQD itself. With Benesi-Hildebrand equation, the binding constant and molar ratio between N-GQD and Al 3+ was calculated to be 4.6 × 10 4 L mol −1 and 1:1 respectively. The p K a value of N-GQD was also determined to be 4.4 by capillary electrophoresis. In pH 4.0 PBS solution, there was a good linear relation between the fluorescence intensity and the logarithm of concentration of Al 3+ in the range of 2.5–75 μmol L −1 , the limit of detection (3σ) was 1.3 μmol L −1 . This “Off - On” fluorescence method had been applied to accurate quantification of aluminum in hydrotalcite tablets. What's more, the fluorescence switch property of N-GQD was explored by alternate addition of Al 3+ and EDTA. The probe was also utilized for detection Al 3+ in living cells due to its excellent biocompatibility. [ABSTRACT FROM AUTHOR]

Although the organic light-emitting devices (OLEDs) encompassing TVs, smartphones, and wearable devices, etc. already have been commercialized, there is still room to pursue material improvements in efficiency and cost-effectiveness. Organic light-emitting materials have experienced the development of the three generation system, it is timely to summary the recent advances and the remaining challenges of the materials as well as their corresponding devices. Special attention is mainly concentrated on describing the blue material structures and related electroluminescence (EL) device performances (the maximum EQE data, Commission Internationale de l’Eclairage (CIE) coordinates, and efficiency roll-off). This short review will show the current governing hotspots concerning OLEDs in academic fields, which may pave the way for next step of industrial application. [ABSTRACT FROM AUTHOR]