Abstract
This paper aims to investigate the dynamic event-triggered control problem for networked predictive control systems with random delays and disturbance. First, a discrete-time dynamic ...event-triggered control scheme, in which sensor information is only updated when it is necessary, is presented. Next, the systems are modeled as a time-delay singular Markovian jump systems with time-varying switching. Then, a dynamic event-triggered delay compensation control strategy is proposed. Sufficient conditions guaranteeing the asymptotically stable are derived based on the Lyapunov–Krasovskii functional method together with the linear matrix inequality (LMI) technique. Finally, simulation results verify the effectiveness of the proposed strategy.
LiNi
Mn
Co
O
-layered cathode is often fabricated in the form of secondary particles, consisting of densely packed primary particles. This offers advantages for high energy density and alleviation of ...cathode side reactions/corrosions, but introduces drawbacks such as intergranular cracking. Here, we report unexpected observations on the nucleation and growth of intragranular cracks in a commercial LiNi
Mn
Co
O
cathode by using advanced scanning transmission electron microscopy. We find the formation of the intragranular cracks is directly associated with high-voltage cycling, an electrochemically driven and diffusion-controlled process. The intragranular cracks are noticed to be characteristically initiated from the grain interior, a consequence of a dislocation-based crack incubation mechanism. This observation is in sharp contrast with general theoretical models, predicting the initiation of intragranular cracks from grain boundaries or particle surfaces. Our study emphasizes that maintaining structural stability is the key step towards high-voltage operation of layered-cathode materials.
The seriousness of the energy crisis and the environmental impact of global anthropogenic activities have led to an urgent need to develop efficient and green fuels. Hydrogen, as a promising ...alternative resource that is produced in an environmentally friendly and sustainable manner by a water splitting reaction, has attracted extensive attention in recent years. However, the large‐scale application of water splitting devices is hindered predominantly by the sluggish oxygen evolution reaction (OER) at the anode. Therefore, the design and exploration of high‐performing OER electrocatalysts is a critical objective. Considering their low prices, abundant reserves, and intrinsic activities, NiFe‐based bimetal compounds are widely studied as excellent OER electrocatalysts. Moreover, recent progress on NiFe‐based OER electrocatalysts in alkaline environments is comprehensively and systematically introduced through various catalyst families including NiFe‐layered hydroxides, metal–organic frameworks, NiFe‐based (oxy)hydroxides, NiFe‐based oxides, NiFe alloys, and NiFe‐based nonoxides. This review briefly introduces the advanced NiFe‐based OER materials and their corresponding reaction mechanisms. Finally, the challenges inherent to and possible strategies for producing extraordinary NiFe‐based electrocatalysts are discussed.
This review briefly introduces the advanced NiFe‐based oxygen evolution reaction (OER) materials and their corresponding reaction mechanisms. After providing this background, recent progress on NiFe‐based OER electrocatalysts through various catalyst families is comprehensively and systematically presented, and the inherent challenges and probable strategies for producing extraordinary NiFe‐based electrocatalysts are finally discussed.
Here we propose a real-time method for low-drift odometry and mapping using range measurements from a 3D laser scanner moving in 6-DOF. The problem is hard because the range measurements are received ...at different times, and errors in motion estimation (especially without an external reference such as GPS) cause mis-registration of the resulting point cloud. To date, coherent 3D maps have been built by off-line batch methods, often using loop closure to correct for drift over time. Our method achieves both low-drift in motion estimation and low-computational complexity. The key idea that makes this level of performance possible is the division of the complex problem of Simultaneous Localization and Mapping, which seeks to optimize a large number of variables simultaneously, into two algorithms. One algorithm performs odometry at a high-frequency but at low fidelity to estimate velocity of the laser scanner. Although not necessary, if an IMU is available, it can provide a motion prior and mitigate for gross, high-frequency motion. A second algorithm runs at an order of magnitude lower frequency for fine matching and registration of the point cloud. Combination of the two algorithms allows map creation in real-time. Our method has been evaluated by indoor and outdoor experiments as well as the KITTI odometry benchmark. The results indicate that the proposed method can achieve accuracy comparable to the state of the art offline, batch methods.
Rechargeable lithium‐metal batteries (LMBs) are regarded as the “holy grail” of energy‐storage systems, but the electrolytes that are highly stable with both a lithium‐metal anode and high‐voltage ...cathodes still remain a great challenge. Here a novel “localized high‐concentration electrolyte” (HCE; 1.2 m lithium bis(fluorosulfonyl)imide in a mixture of dimethyl carbonate/bis(2,2,2‐trifluoroethyl) ether (1:2 by mol)) is reported that enables dendrite‐free cycling of lithium‐metal anodes with high Coulombic efficiency (99.5%) and excellent capacity retention (>80% after 700 cycles) of Li||LiNi1/3Mn1/3Co1/3O2 batteries. Unlike the HCEs reported before, the electrolyte reported in this work exhibits low concentration, low cost, low viscosity, improved conductivity, and good wettability that make LMBs closer to practical applications. The fundamental concept of “localized HCEs” developed in this work can also be applied to other battery systems, sensors, supercapacitors, and other electrochemical systems.
A novel “localized high‐concentration electrolyte,” which consists of 1.2 m lithium bis(fluorosulfonyl)imide in a mixture of dimethyl carbonate/bis(2,2,2‐trifluoroethyl) ether (1:2 by mol), enables dendrite‐free cycling of lithium‐metal anodes with high Coulombic efficiency of 99.3% and excellent capacity retention (>80% after 700 cycles) of Li||LiNi1/3Mn1/3Co1/3O2 batteries.
Porous silicon (Si)/carbon nanocomposites have been extensively explored as a promising anode material for high‐energy lithium (Li)‐ion batteries (LIBs). However, shrinking of the pores and sintering ...of Si in the nanoporous structure during fabrication often diminishes the full benefits of nanoporous Si. Herein, a scalable method is reported to preserve the porous Si nanostructure by impregnating petroleum pitch inside of porous Si before high‐temperature treatment. The resulting micrometer‐sized Si/C composite maintains a desired porosity to accommodate large volume change and high conductivity to facilitate charge transfer. It also forms a stable surface coating that limits the penetration of electrolyte into nanoporous Si and minimizes the side reaction between electrolyte and Si during cycling and storage. A Si‐based anode with 80% of pitch‐derived carbon/nanoporous Si enables very stable cycling of a Si||Li(Ni0.5Co0.2Mn0.3)O2 (NMC532) battery (80% capacity retention after 450 cycles). It also leads to low swelling in both particle and electrode levels required for the next generation of high‐energy LIBs. The process also can be used to preserve the porous structure of other nanoporous materials that need to be treated at high temperatures.
A micrometer‐sized silicon/carbon composite anode developed by facile and scalable impregnation of petroleum pitch that stabilizes nanoporous Si against sintering at high temperature is reported. The composite anode including single nanometer‐sized primary particles shielded by pitch‐derived carbon exhibits outstanding battery performance such as 80% capacity retention after 450 cycles in the full cell system.
High-energy rechargeable lithium (Li) metal batteries (LMBs) with Li metal anode (LMA) were first developed in the 1970s, but their practical applications have been hindered by the safety and ...low-efficiency concerns related to LMA. Recently, a worldwide effort on LMA-based rechargeable LMBs has been revived to replace graphite-based, Li-ion batteries because of the much higher energy density that can be achieved with LMBs. This review focuses on the recent progress on the stabilization of LMA with nonaqueous electrolytes and reveals the fundamental mechanisms behind this improved stability. Various strategies that can enhance the stability of LMA in practical conditions and perspectives on the future development of LMA are also discussed. These strategies include the use of novel electrolytes such as superconcentrated electrolytes, localized high-concentration electrolytes, and highly fluorinated electrolytes, surface coatings that can form a solid electrolyte interphase with a high interfacial energy and self-healing capabilities, development of “anode-free” Li batteries to minimize the interaction between LMA and electrolyte, approaches to enable operation of LMA in practical conditions, etc. Combination of these strategies ultimately will lead us closer to the large-scale application of LMBs which often is called the “Holy Grail” of energy storage systems.
Considering the limited energy density of traditional graphite-anode-based lithium (Li)-ion batteries, alternative high-capacity anodes are greatly needed for the next-generation high-energy-density ...battery systems. In this regard, Li metal is well known to be one of the most promising anodes due to its ultrahigh capacity (3,860 mAh g−1) and the very low standard negative electrochemical potential (−3.040 V). However, dendrite growth and high reactivity of Li metal anodes result in low cycling efficiency and severe safety concerns. The recent revival of research and development on Li metal anodes has brought new, in-depth understanding and key experimental progress toward Li metal protection and enhanced performance of Li metal batteries. In this Perspective, we concisely review recent discoveries in this field and suggest possible new research directions for further development of Li metal batteries.
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Lithium (Li)-ion batteries have been widely used as power sources for portable electronic devices and are emerging into transportation and grid applications, but the energy density of the state-of-the-art Li-ion batteries will reach its theoretical limit soon, and new battery designs are urgently needed to satisfy the increasing demand for high-energy-density batteries. In this regard, Li metal anode material has attracted worldwide attention because of its many merits. Although practical applications of Li metal anodes are still limited by several challenges, such as dendrite growth and low coulombic efficiency, rapid development of new materials and electrode designs in recent years has overcome many bottlenecks in this field and hastened the practical applications of high-energy-density and high-performance rechargeable Li metal batteries. In this Perspective, recent significant progress on stabilization of Li metal anodes for Li metal batteries is highlighted. We also present a perspective on future directions and possibilities to better address the existing challenges of Li metal anodes and Li metal batteries.
Recent significant progress on stabilization of lithium (Li) metal anodes for Li metal batteries is highlighted, including suppressing Li dendrite growth by optimization of electrolytes and via membranes and interfacial engineering, and pursuing rational design of anode structures. Several perspectives are proposed for future directions and possibilities of better addressing the existing challenges for Li metal anodes, including stabilizing Li metal anode, inhibiting Li dendrite growth, improving Li CE, and solving many other critical issues.
Facile fabrication of advanced electrode material is highly desired for novel electrochemical sensor development. Herein, cerium oxide (CeO2) nanoparticles were successfully loaded on reduced ...graphene oxide (RGO) by one-step hydrothermal synthesis approach, and the as-prepared nanocomposite (CeO2/RGO) was used as novel electrode material for electrochemical detection of tryptophan. The structure and composition of CeO2/RGO nanocomposite were fully characterized by transmission electron microscope (TEM), X-ray powder diffractometry (XRD) and X-ray photoelectron spectroscopy (XPS), respectively. The electrochemical properties were characterized by several techniques such as cyclic voltammetry (CV), differential pulse voltammetry (DPV), and electrochemical impedance spectroscopy (EIS). It was found that the CeO2/RGO nanocomposite electrode exhibits an enhanced peak current response compared with individual CeO2 or RGO material. The electrochemical sensor based CeO2/RGO material showed a selective and sensitive response toward tryptophan determination, and a linear range of 0.2–25 μM with a detection limit of 80 nM (S/N = 3) was achieved. The present electrochemical sensor displayed an excellent stability and reproducibility, and was successfully applied in the determination of tryptophan in real food and biological samples.
CeO2 was loaded on reduced graphene oxide (CeO2-RGO) and used as active electrode material for electrochemical detection of tryptophan in food and biological samples. Display omitted
•CeO2 loaded on reduced graphene oxide (CeO2-RGO) composite was facilely fabricated by a hydrothermal reduction approach.•The CeO2-RGO was used as a novel electrode material for tryptophan detection.•The present electrochemical sensor exhibited improved analytical performance.•The CeO2-RGO electrode material has been successfully used for tryptophan detection in milk and bovine serum samples.
The conventional LiPF6/carbonate-based electrolytes have been widely used in graphite (Gr)-based lithium (Li) ion batteries (LIBs) for more than 30 years because a stable solid electrolyte interphase ...(SEI) layer forms on the graphite surface and enables its long-term cycling stability. However, few of these electrolytes are stable under the more stringent conditions needed with a Li metal anode (LMA) and other anodes, such as silicon (Si), which exhibit large volume changes during charge/discharge processes. Many different approaches have been developed lately to stabilize Li metal batteries (LMBs) and Si-based LIBs. From this aspect, localized high-concentration electrolytes (LHCEs) have unique advantages: not only are they stable in a wide electrochemical window, they can also form stable SEI layers on LMA and Si anode surfaces to enable their long-term cycling stability. The ultrathin SEI layer formed on a Gr anode can also improve the safety and high-rate operation of conventional LIBs. In this paper, we give a brief summary of our recent work on LHCEs, including their design principle and applications in both LMBs and LIBs. A perspective on the future development of LHCEs is also discussed.
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