Design of Long-Life Wireless Near-Field Hydrogen Gas Sensor.

A compact wireless near-field hydrogen gas sensor is proposed, which detects leaking hydrogen near its source to achieve fast responses and high reliability. A semiconductor-type sensing element is implemented in the sensor, which can provide a significant response in 100 ms when stimulated by pure hydrogen. The overall response time is shortened by orders of magnitude compared to conventional sensors according to simulation results, which will be within 200 ms, compared with over 25 s for spatial concentration sensors under the worst conditions. Over 1 year maintenance intervals are enabled by wireless design based on the Bluetooth low energy protocol. The average energy consumption during a single alarm process is 153 µJ/s. The whole sensor is integrated on a 20 × 26 mm circuit board for compact use.

Probing the Thermal-Driven Structural and Chemical Degradation of Ni-Rich Layered Cathodes by Co/Mn Exchange.

The intrinsic poor thermal stability of layered LiNixCoyMn1-x-yO2 (NCM) cathodes and the exothermic side reactions triggered by the associated oxygen release are the main safety threats for their large-scale implantation. In the NCM family, it is widely accepted that Ni is the stability troublemaker, while Mn has long been considered as a structure stabilizer, whereas the role of Co remains elusive. Here, via Co/Mn exchange in a Ni-rich LiNi0.83Co0.11Mn0.06O2 cathode, we demonstrate that the chemical and structural stability of the deep delithiated NCM cathodes are significantly dominated by Co rather than the widely reported Mn. Operando synchrotron X-ray characterization coupling with in situ mass spectrometry reveal that the Co4+ reduces prior to the reduction of Ni4+ and could thus prolong the Ni migration by occupying the tetrahedra sites and, hence, postpone the oxygen release and thermal failure. In contrast, the Mn itself is stable, but barely stabilizes the Ni4+. Our results highlight the importance of evaluating the intrinsic role of compositional tuning on the Ni-rich/Co-free layered oxide cathode materials to guarantee the safe operation of high-energy Li-ion batteries.

Chemical-Free Recycling of Cathode Material and Aluminum Foil from Waste Lithium-Ion Batteries by Combining Plasma and Ultrasonic Technology.

With the rapid demand for lithium-ion batteries due to the widespread application of electric vehicles, a significant amount of battery electrode pieces requiring urgent treatment are generated during battery production and disposal. The strong bonding caused by the presence of binders makes it challenging to achieve thorough separation between the cathode active materials and Al foil, posing difficulties in efficient battery material recycling. To address this issue, a plasma-ultrasonically combined physical separation method is proposed in this study. This method utilizes plasma-generated excited-state radicals assisted by ultrasonic waves to separate active materials and current collectors. The results indicate that the binders are effectively decomposed under plasma treatment at 13.56 MHz, 100 W, and 10 min in an oxygen atmosphere, resulting in a separation efficiency of 96.8 wt % for the cathode materials. Characterization results demonstrate that the morphology, crystal structure, and chemical composition of the recycled cathode active materials remain unchanged, facilitating subsequent direct restoration and hydrometallurgical recycling. Simultaneously, the Al foil is also completely recycled for subsequent reuse. Compared with traditional methods of separating cathode active materials and aluminum foil, the method proposed in this study has significant economic and environmental potential. It can promote the recycling of battery materials and the development of sustainable transportation.

Smart Solid-State Interphases Enable High-Safety and High-Energy Practical Lithium Batteries.

With the electrochemical performance of batteries approaching the bottleneck gradually, it is increasingly urgent to solve the safety issue. Herein, all-in-one strategy is ingeniously developed to design smart, safe, and simple (3S) practical pouch-type LiNi0.8Co0.1Mn0.1O2||Graphite@SiO (NCM811||Gr@SiO) cell, taking full advantage of liquid and solid-state electrolytes. Even under the harsh thermal abuse and high voltage condition (100 °C, 3-4.5 V), the pouch-type 3S NCM811||Gr@SiO cell can present superior capacity retention of 84.6% after 250 cycles (based pouch cell: 47.8% after 250 cycles). More surprisingly, the designed 3S NCM811||Gr@SiO cell can efficiently improve self-generated heat T1 by 45 °C, increase TR triggering temperature T2 by 40 °C, and decrease the TR highest T3 by 118 °C. These superior electrochemical and safety performances of practical 3S pouch-type cells are attributed to the robust and stable anion-induced electrode-electrolyte interphases and local solid-state electrolyte protection layer. All the fundamental findings break the conventional battery design guidelines and open up a new direction to develop practical high-performance batteries.

Initial stage oxidation corrosion of commercial ferritic stainless steels with different Cr contents at 650 °C for solid oxide fuel cells.

Selecting adequate ferritic stainless steel (FSS) with a high corrosion resistance and a low cost is critical for solid oxide fuel cells (SOFCs) operating at intermediate temperature. In this study, the corrosion behaviors of four commercial FSSs involving TS430, TY441, YG442, and TY445 with a Cr content ranging from 16.18 wt.% to 21.73 wt.% are investigated at 650 °C. The oxidation mass gains, microstructures of surface oxide scale, and electrical conductivities are measured. The effects of grain size as well as doped elements are estimated together with the Cr volatilization. Flaky Cr2O3 particles are formed on TS430 and TY441 dominated by the outward migration of Cr3+. In comparison, a thin and dense layer of chromia is observed on YG442 and TY445. A high Cr content and a uniformly distributed grain size are conducive to the formation of a thin and dense chromia scale on the FSS surface during the initial oxidation process. On the other hand, the addition of Nb, Ti, and Mo weakens the outward diffusion of Cr3+ and reduces the particle size of chromia. After oxidation at 650 °C for 120 h, scattered (Mn, Cr)3O4 spinel particles occur on TS430, YG442, and TY445. TY445 and YG442 exhibit a higher conductivity although all the results of area specific resistance (ASR) are less than 6 mΩ·cm2. Meanwhile, the effect of Cr volatilization is enlarged on the estimation of mass gain at 650 °C compared with even higher temperatures.

In Situ Polymerization Facilitating Practical High-Safety Quasi-Solid-State Batteries.

Quasi-solid-state batteries (QSSBs) are gaining widespread attention as a promising solution to improve battery safety performance. However, the safety improvement and the underlying mechanisms of QSSBs remain elusive. Herein, a novel strategy combining high-safety ethylene carbonate-free liquid electrolyte and in situ polymerization technique is proposed to prepare practical QSSBs. The Ah-level QSSBs with LiNi0.83Co0.11Mn0.06O2 cathode and graphite-silicon anode demonstrate significantly improved safety features without sacrificing electrochemical performance. As evidenced by accelerating rate calorimetry tests, the QSSBs exhibit increased self-heating temperature and onset temperature (T2), and decreased temperature rise rate during thermal runaway (TR). The T2 has a maximum increase of 48.4 °C compared to the conventional liquid batteries. Moreover, the QSSBs do not undergo TR until 180 °C (even 200 °C) during the hot-box tests, presenting significant improvement compared to the liquid batteries that run into TR at 130 °C. Systematic investigations show that the in situ formed polymer skeleton effectively mitigates the exothermic reactions between lithium salts and lithiated anode, retards the oxygen release from cathode, and inhibits crosstalk reactions between cathode and anode at elevated temperatures. The findings offer an innovative solution for practical high-safety QSSBs and open up a new sight for building safer high-energy-density batteries.

All-temperature area battery application mechanism, performance, and strategies.

Further applications of electric vehicles (EVs) and energy storage stations are limited because of the thermal sensitivity, volatility, and poor durability of lithium-ion batteries (LIBs), especially given the urgent requirements for all-climate utilization and fast charging. This study comprehensively reviews the thermal characteristics and management of LIBs in an all-temperature area based on the performance, mechanism, and thermal management strategy levels. At the performance level, the external features of the batteries were analyzed and compared in cold and hot environments. At the mechanism level, the heat generation principles and thermal features of LIBs under different temperature conditions were summarized from the perspectives of thermal and electrothermal mechanisms. At the strategy level, to maintain the temperature/thermal consistency and prevent poor subzero temperature performance and local/global overheating, conventional and novel battery thermal management systems (BTMSs) are discussed from the perspective of temperature control, thermal consistency, and power cost. Moreover, future countermeasures to enhance the performance of all-climate areas at the material, cell, and system levels are discussed. This study provides insights and methodologies to guarantee the performance and safety of LIBs used in EVs and energy storage stations.

Realistic fault detection of li-ion battery via dynamical deep learning.

Accurate evaluation of Li-ion battery (LiB) safety conditions can reduce unexpected cell failures, facilitate battery deployment, and promote low-carbon economies. Despite the recent progress in artificial intelligence, anomaly detection methods are not customized for or validated in realistic battery settings due to the complex failure mechanisms and the lack of real-world testing frameworks with large-scale datasets. Here, we develop a realistic deep-learning framework for electric vehicle (EV) LiB anomaly detection. It features a dynamical autoencoder tailored for dynamical systems and configured by social and financial factors. We test our detection algorithm on released datasets comprising over 690,000 LiB charging snippets from 347 EVs. Our model overcomes the limitations of state-of-the-art fault detection models, including deep learning ones. Moreover, it reduces the expected direct EV battery fault and inspection costs. Our work highlights the potential of deep learning in improving LiB safety and the significance of social and financial information in designing deep learning models.

Ni electrodes with 3D-ordered surface structures for boosting bubble releasing toward high current density alkaline water splitting.

The performance of alkaline water electrolysis (AWE) at high current densities is limited by gas bubble generation on the surface of electrodes, which covers active sites and blocks mass transfer, resulting in lower AWE efficiency. Here, we utilize electro-etching to construct Ni electrodes with hydrophilic and aerophobic surfaces to improve the efficiency of AWE. Ni atoms on the Ni surface can be exfoliated orderly along the crystal planes by electro-etching, forming micro-nano-scale rough surfaces with multiple crystal planes exposed. The 3D-ordered surface structures increase the exposure of active sites and promote the removal of bubbles on the surface of the electrode during the AWE process. In addition, experimental results from high-speed camera reveal that rapidly released bubbles can improve the local circulation of electrolyte. Lastly, the accelerated durability test based on practical working condition demonstrates that the 3D-ordered surface structures are robust and durable during the AWE process.

Enabling Electrochemical-Mechanical Robustness of Ultra-High Ni Cathode via Self-Supported Primary-Grain-Alignment Strategy.

The electrochemical-mechanical degradation of ultrahigh Ni cathode for lithium-ion batteries is a crucial aspect that limits the cycle life and safety of devices. Herein, the study reports a facile strategy involving rational design of primary grain crystallographic orientation within polycrystalline cathode, which well enhanced its electro-mechanical strength and Li+ transfer kinetics. Ex situ and in situ experiments/simulations including cross-sectional particle electron backscatter diffraction (EBSD), single-particle micro-compression, thermogravimetric analysis combined with mass spectrometry (TGA-MS), and finite element modeling reveal that, the primary-grain-alignment strategy effectively mitigates the particle pulverization, lattice oxygen release thereby enhances battery cycle life and safety. Besides the preexisting doping and coating methodologies to improve the stability of Ni-rich cathode, the primary-grain-alignment strategy, with no foreign elements or heterophase layers, is unprecedently proposed here. The results shed new light on the study of electrochemical-mechanical strain alleviation for electrode materials.

High stability and high performance nitrogen doped carbon containers for lithium-ion batteries.

For a long time, carbon has been an ideal material for various electrochemical energy storage devices and a key component in electrochemical energy storage systems due to its advantages of rich surface states, easy tenability, and good chemical stability. Stable and high-performance carbon materials can support future applications of high specific energy electrodes. Herein and for the first time, we have designed nitrogen-doped carbon hollow containers using oleylamine-coating TiO2 mesocrystals as a precursor with a high specific surface area of 1231 m2 g-1. When applied as an anode for lithium-ion storage, a reversible capacity of 774.5 mA h g-1 is obtained at a rate of 0.5 A g-1 after 200 cycles. Meanwhile, at an even higher rate of 2 A g-1, a capacity of 721.1 mA h g-1 is still achieved after 500 cycles. Moreover, the carbon containers remain structurally intact after a series of cycles. This may be attributed to the nitrogen atoms doped on the carbon surface that can absorb multiple lithium ions and enhance the structural stability. These results provide technical support for the development of high specific energy electrode materials.

Synergistic Dual-Salt Electrolyte for Safe and High-Voltage LiNi0.8Co0.1Mn0.1O2//Graphite Pouch Cells.

Concerns about thermal safety and unresolved high-voltage stability have impeded the commercialization of high-energy lithium-ion batteries bearing LiNi0.8Co0.1Mn0.1O2 (NCM811) cathodes. Enhancing the cathode structure and optimizing the electrolyte formula have demonstrated significant potential in improving the high-voltage properties of batteries while simultaneously minimizing thermal hazards. The current study reports the development of a high-voltage lithium-ion battery that is both safe and reliable, using single-crystal NCM811 and a dual-salt electrolyte (DSE). After 200 cycles at high voltage (up to 4.5 V), the capacity retention of the battery with DSE was 98.80%, while that for the battery with a traditional electrolyte was merely 86.14%. Additionally, in comparison to the traditional electrolyte, the DSE could raise the tipping temperature of a battery's thermal runaway (TR) by 31.1 °C and lower the maximum failure temperature by 76.1 °C. Moreover, the DSE could effectively reduce the battery's TR heat release rate (by 23.08%) as well as eliminate concerns relating to fire hazards (no fire during TR). Based on material characterization, the LiDFOB and LiBF4 salts were found to facilitate the in situ formation of an F- and B-rich cathode-electrolyte interphase, which aids in inhibiting oxygen and interfacial side reactions, thereby reducing the intensity of redox reactions within the battery. Therefore, the findings indicate that DSE is promising as a safe and high-voltage lithium-ion battery material.

The void formation behaviors in working solid-state Li metal batteries.

The fundamental understanding of the elusive evolution behavior of the buried solid-solid interfaces is the major barrier to exploring solid-state electrochemical devices. Here, we uncover the interfacial void evolution principles in solid-state batteries, build a solid-state void nucleation and growth model, and make an analogy with the bubble formation in liquid phases. In solid-state lithium metal batteries, the lithium stripping-induced interfacial void formation determines the morphological instabilities that result in battery failure. The void-induced contact loss processes are quantified in a phase diagram under wide current densities ranging from 1.0 to 10.0 milliamperes per square centimeter by rational electrochemistry calculations. The in situ-visualized morphological evolutions reveal the microscopic features of void defects under different stripping circumstances. The electrochemical-morphological relationship helps to elucidate the current density- and areal capacity-dependent void nucleation and growth mechanisms, which affords fresh insights on understanding and designing solid-solid interfaces for advanced solid-state batteries.

Thermal Runaway of Nonflammable Localized High-Concentration Electrolytes for Practical LiNi0.8 Mn0.1 Co0.1 O2 |Graphite-SiO Pouch Cells.

With continuous improvement of batteries in energy density, enhancing their safety is becoming increasingly urgent. Herein, practical high energy density LiNi0.8 Mn0.1 Co0.1 O2 |graphite-SiO pouch cell with nonflammable localized high concentration electrolyte (LHCE) is proposed that presents unique self-discharge characteristic before thermal runaway (TR), thus effectively reducing safety hazards. Compared with the reference electrolyte, pouch cell with nonflammable LHCE can increase self-generated heat temperature by 4.4 °C, increase TR triggering temperature by 47.3 °C, decrease the TR highest temperature by 71.8 °C, and extend the time from self-generated heat to triggering TR by ≈8 h. In addition, the cell with nonflammable LHCE presents superior high voltage cycle stability, attributed to the formation of robust inorganic-rich electrode-electrolyte interphase. The strategy represents a pivotal step forward for practical high energy and high safety batteries.

Eliminating interfacial O-involving degradation in Li-rich Mn-based cathodes for all-solid-state lithium batteries.

In the pursuit of energy-dense all-solid-state lithium batteries (ASSBs), Li-rich Mn-based oxide (LRMO) cathodes provide an exciting path forward with unexpectedly high capacity, low cost, and excellent processibility. However, the cause for LRMO|solid electrolyte interfacial degradation remains a mystery, hindering the application of LRMO-based ASSBs. Here, we first reveal that the surface oxygen instability of LRMO is the driving force for interfacial degradation, which severely blocks the interfacial Li-ion transport and triggers fast battery failure. By replacing the charge compensation of surface oxygen with sulfite, the overoxidation and interfacial degradation can be effectively prevented, therefore achieving a high specific capacity (~248 mAh g-1, 1.1 mAh cm-2; ~225 mAh g-1, 2.9 mAh cm-2) and excellent long-term cycling stability of >300 cycles with 81.2% capacity retention at room temperature. These findings emphasize the importance of irreversible anion reactions in interfacial failure and provide fresh insights into constructing stable interfaces in LRMO-based ASSBs.

Fire boundaries of lithium-ion cell eruption gases caused by thermal runaway.

Lithium-ion batteries are applied in electric vehicles to mitigate climate change. However, their practical applications are impeded by poor safety performance owing mainly to the cell eruption gas (CEG) fire triangle. Here, we report quantitatively the three fire boundaries corresponding to the CEG fire triangle of four types of mainstream cells with the state of charge (SOC) values ranging from 0% to 143% based on 29 thermal runaway tests conducted in an inert atmosphere in open literature. Controlling the SOC and/or selecting a reasonable cell type can alter the minimum CEG and oxygen concentrations required for ignition, thereby changing the probability of a battery fire. The ignition temperature varies greatly according to the type of ignition source type. Temperature and ignition source type play a leading role in the ignition mode. Breaking any fire boundary will stop the ignition of CEG, thus significantly improving the battery safety performance.

Comprehensive early warning strategies based on consistency deviation of thermal-electrical characteristics for energy storage grid.

Lithium iron phosphate (LiFePO4) batteries have been dominant in energy storage systems. However, it is difficult to estimate the state of charge (SOC) and safety early warning of the batteries. To solve these problems, this paper developed a multiple timescale comprehensive early warning strategy based on the consistency deviation of the electrical and thermal characteristics of LiFePO4 batteries. The unscented Kalman filter method was employed to estimate the battery SOC. The established comprehensive early warning strategy was verified through fault-triggered experiments at different time scales with different equivalent resistances. The results show that the comprehensive early warning strategy can realize early warning for different timescale failures of LiFePO4 batteries under different energy storage conditions. For more dangerous severe failures that can break the safety valve, safety early warning can be realized 15 min in advance. This study provides a reference to ensure safe and reliable operations of energy storage systems.

Drive circuitry of an electric vehicle enabling rapid heating of the battery pack at low temperatures.

Heating battery at low temperatures is fundamental to avoiding the range anxiety and the time-consuming charging associated with electric vehicles (EVs). One method for achieving fast and uniform battery heating is to polarize the cell under pulse currents. However, the on-board implementation of this method leads to an increase in the cost and size. Therefore, in this study, an adapted EV circuitry compatible with the existing one and an optimized operating condition are proposed to enable rapid battery heating. With this circuit, electricity transfer between the cells can be realized through a motor, leading to remarkably higher battery currents than those of the conventional circuit. The increase in the maximum heating currents (from 1.41C to 4C) resulted in a battery temperature rise of 8.6°C/min at low temperatures. This heating method exhibits low cost, high efficiency, and negligible effects on battery degradation, practical and promising on battery heating of EVs.

In situ observation of thermal-driven degradation and safety concerns of lithiated graphite anode.

Graphite, a robust host for reversible lithium storage, enabled the first commercially viable lithium-ion batteries. However, the thermal degradation pathway and the safety hazards of lithiated graphite remain elusive. Here, solid-electrolyte interphase (SEI) decomposition, lithium leaching, and gas release of the lithiated graphite anode during heating were examined by in situ synchrotron X-ray techniques and in situ mass spectroscopy. The source of flammable gas such as H2 was identified and quantitively analyzed. Also, the existence of highly reactive residual lithium on the graphite surface was identified at high temperatures. Our results emphasized the critical role of the SEI in anode thermal stability and uncovered the potential safety hazards of the flammable gases and leached lithium. The anode thermal degradation mechanism revealed in the present work will stimulate more efforts in the rational design of anodes to enable safe energy storage.

Thermal runaway of Lithium-ion batteries employing LiN(SO2F)2-based concentrated electrolytes.

Concentrated electrolytes usually demonstrate good electrochemical performance and thermal stability, and are also supposed to be promising when it comes to improving the safety of lithium-ion batteries due to their low flammability. Here, we show that LiN(SO2F)2-based concentrated electrolytes are incapable of solving the safety issues of lithium-ion batteries. To illustrate, a mechanism based on battery material and characterizations reveals that the tremendous heat in lithium-ion batteries is released due to the reaction between the lithiated graphite and LiN(SO2F)2 triggered thermal runaway of batteries, even if the concentrated electrolyte is non-flammable or low-flammable. Generally, the flammability of an electrolyte represents its behaviors when oxidized by oxygen, while it is the electrolyte reduction that triggers the chain of exothermic reactions in a battery. Thus, this study lights the way to a deeper understanding of the thermal runaway mechanism in batteries as well as the design philosophy of electrolytes for safer lithium-ion batteries.