Shepherding Slots to Objects: Towards Stable and Robust Object-Centric Learning

Object-centric learning (OCL) aspires general and compositional understanding of scenes by representing a scene as a collection of object-centric representations. OCL has also been extended to multi-view image and video datasets to apply various data-driven inductive biases by utilizing geometric or temporal information in the multi-image data. Single-view images carry less information about how to disentangle a given scene than videos or multi-view images do. Hence, owing to the difficulty of applying inductive biases, OCL for single-view images remains challenging, resulting in inconsistent learning of object-centric representation. To this end, we introduce a novel OCL framework for single-view images, SLot Attention via SHepherding (SLASH), which consists of two simple-yet-effective modules on top of Slot Attention. The new modules, Attention Refining Kernel (ARK) and Intermediate Point Predictor and Encoder (IPPE), respectively, prevent slots from being distracted by the background noise and indicate locations for slots to focus on to facilitate learning of object-centric representation. We also propose a weak semi-supervision approach for OCL, whilst our proposed framework can be used without any assistant annotation during the inference. Experiments show that our proposed method enables consistent learning of object-centric representation and achieves strong performance across four datasets. Code is available at \url{https://github.com/object-understanding/SLASH}

A cooperative biphasic MoOx–MoPx promoter enables a fast-charging lithium-ion battery

The realisation of fast-charging lithium-ion batteries with long cycle lifetimes is hindered by the uncontrollable plating of metallic Li on the graphite anode during high-rate charging. Here we report that surface engineering of graphite with a cooperative biphasic MoOx–MoPx promoter improves the charging rate and suppresses Li plating without compromising energy density. We design and synthesise MoOx–MoPx/graphite via controllable and scalable surface engineering, i.e., the deposition of a MoOx nanolayer on the graphite surface, followed by vapour-induced partial phase transformation of MoOx to MoPx. A variety of analytical studies combined with thermodynamic calculations demonstrate that MoOx effectively mitigates the formation of resistive films on the graphite surface, while MoPx hosts Li+ at relatively high potentials via a fast intercalation reaction and plays a dominant role in lowering the Li+ adsorption energy. The MoOx–MoPx/graphite anode exhibits a fast-charging capability (<10 min charging for 80% of the capacity) and stable cycling performance without any signs of Li plating over 300 cycles when coupled with a LiNi0.6Co0.2Mn0.2O2 cathode. Thus, the developed approach paves the way to the design of advanced anode materials for fast-charging Li-ion batteries. © 2021, The Author(s).1

Machine Learning-Based Vehicle Trajectory Prediction Using V2V Communications and On-Board Sensors

Predicting the trajectories of surrounding vehicles is important to avoid or mitigate collision with traffic participants. However, due to limited past information and the uncertainty in future driving maneuvers, trajectory prediction is a challenging task. Recently, trajectory prediction models using machine learning algorithms have been addressed solve to this problem. In this paper, we present a trajectory prediction method based on the random forest (RF) algorithm and the long short term memory (LSTM) encoder-decoder architecture. An occupancy grid map is first defined for the region surrounding the target vehicle, and then the row and the column that will be occupied by the target vehicle at future time steps are determined using the RF algorithm and the LSTM encoder-decoder architecture, respectively. For the collection of training data, the test vehicle was equipped with a camera and LIDAR sensors along with vehicular wireless communication devices, and the experiments were conducted under various driving scenarios. The vehicle test results demonstrate that the proposed method provides more robust trajectory prediction compared with existing trajectory prediction methods

Driving Environment Perception Based on the Fusion of Vehicular Wireless Communications and Automotive Remote Sensors

Driving environment perception for automated vehicles is typically achieved by the use of automotive remote sensors such as radars and cameras. A vehicular wireless communication system can be viewed as a new type of remote sensor that plays a central role in connected and automated vehicles (CAVs), which are capable of sharing information with each other and also with the surrounding infrastructure. In this paper, we present the design and implementation of driving environment perception based on the fusion of vehicular wireless communications and automotive remote sensors. A track-to-track fusion of high-level sensor data and vehicular wireless communication data was performed to accurately and reliably locate the remote target in the vehicle surroundings and predict the future trajectory. The proposed approach was implemented and evaluated in vehicle tests conducted at a proving ground. The experimental results demonstrate that using vehicular wireless communications in conjunction with the on-board sensors enables improved perception of the surrounding vehicle located at varying longitudinal and lateral distances. The results also indicate that vehicle future trajectory and potential crash involvement can be reliably predicted with the proposed system in different cut-in driving scenarios

High-performance bifunctional electrocatalyst for iron-chromium redox flow batteries

Despite a variety of advantages over the presently dominant vanadium redox flow batteries, the commercialization of iron-chromium redox flow batteries (ICRFBs) is hindered by sluggish Cr2+/Cr3+ redox reactions and vulnerability to the hydrogen evolution reaction (HER). To address these issues, here, we report a promising electrocatalyst comprising Ketjenblack (KB) carbon with embedded bismuth nanoparticles (Bi-C). The uniform incorporation of Bi nanoparticles into KB carbon via a simple reduction process excellently promotes the electrochemical activity of Cr2+/Cr3+ redox reactions while retarding the HER. A combination of experimental analysis and density functional theory (DFT) calculations indicates that these phenomena are attributable to the synergistic effect of Bi and KB, which inhibits hydrogen evolution and provides active sites to enhance the Cr2+/ Cr3+ redox reaction, respectively. An ICRFB cell containing the Bi-C catalyst as the negative electrode exhibits a high energy efficiency of 86.54% with excellent capacity retention during charge-discharge cycling at room temperature. This study offers an intelligent hybrid material as a useful design principle for electrocatalysts capable of addressing the critical problems in ICRFBs.

Liquid electrolyte-free cathode for long-cycle life lithium–oxygen batteries

Ether-based organic liquid electrolytes (OLEs) have been commonly used in lithium–oxygen batteries (LOBs); however, they become unstable and cause rapid performance degradation during LOB operation. To address these problems, in this study we propose an OLE-free cathode architecture based on a Li+-selective solid membrane (LSSM). An LSSM with a seamless duplex (dense/porous) architecture is prepared by a tape casting process combined with co-sintering, and carbon nanotubes (CNTs) decorated with Au nanoparticles (CNT@Au) are directly formed on its porous framework. We show that the duplex-LSSM can effectively protect the metallic Li anode from parasitic reactions with impurity species and improve the cycling stability of Li. Furthermore, an LOB assembled with the duplex-LSSM and CNT@Au components exhibits a discharge capacity as high as 3650 mAh g−1 and improved cycling stability (>140 cycles) compared to a conventional OLE-based LOB; this can be explained in terms of the combined advantages provided by the OLE-free cathode and the LSSM-protected Li anode. © 2021 Elsevier B.V.1

Functionality of Dual-Phase Lithium Storage in a Porous Carbon Host for Lithium-Metal Anode

© 2020 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim Lithium (Li) metal is regarded as the most attractive anode material for high-energy Li batteries, but it faces unavoidable challenges—uncontrollable dendritic growth of Li and severe volume changes during Li plating and stripping. Herein, a porous carbon framework (PCF) derived from a metal–organic framework (MOF) is proposed as a dual-phase Li storage material that enables efficient and reversible Li storage via lithiation and metallization processes. Li is electrochemically stored in the PCF upon charging to 0 V versus Li/Li+ (lithiation), making the PCF surface more lithiophilic, and then the formation of metallic Li phase can be induced spontaneously in the internal nanopores during further charging below 0 V versus Li/Li+ (metallization). Based on thermodynamic calculations and experimental studies, it is shown that atomically dispersed zinc plays an important role in facilitating Li plating and that the reversibility of Li storage is significantly improved by controlled nanostructural engineering of 3D porous nanoarchitectures to promote the uniform formation of Li. Moreover, the MOF-derived PCF does not suffer from macroscopic volume changes during cycling. This work demonstrates that the nanostructural engineering of porous carbon structures combined with lithiophilic element coordination would be an effective approach for realizing high-capacity, reversible Li-metal anodes

Functionality of Dual‐Phase Lithium Storage in a Porous Carbon Host for Lithium‐Metal Anode

© 2020 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim Lithium (Li) metal is regarded as the most attractive anode material for high-energy Li batteries, but it faces unavoidable challenges—uncontrollable dendritic growth of Li and severe volume changes during Li plating and stripping. Herein, a porous carbon framework (PCF) derived from a metal–organic framework (MOF) is proposed as a dual-phase Li storage material that enables efficient and reversible Li storage via lithiation and metallization processes. Li is electrochemically stored in the PCF upon charging to 0 V versus Li/Li+ (lithiation), making the PCF surface more lithiophilic, and then the formation of metallic Li phase can be induced spontaneously in the internal nanopores during further charging below 0 V versus Li/Li+ (metallization). Based on thermodynamic calculations and experimental studies, it is shown that atomically dispersed zinc plays an important role in facilitating Li plating and that the reversibility of Li storage is significantly improved by controlled nanostructural engineering of 3D porous nanoarchitectures to promote the uniform formation of Li. Moreover, the MOF-derived PCF does not suffer from macroscopic volume changes during cycling. This work demonstrates that the nanostructural engineering of porous carbon structures combined with lithiophilic element coordination would be an effective approach for realizing high-capacity, reversible Li-metal anodes

Deciphering the critical degradation factors of solid composite electrodes with halide electrolytes: Interfacial reaction versus ionic transport

Recently, halide-type Li+ conductors have been revisited for their use in all-solid-state batteries (ASSBs) owing to their stability at high potentials. However, the realization of ASSBs is hindered by the fast performance decay of composite cathodes. From a comparative study using halide and sulfide solid electrolytes (SEs), herein, we reveal the critical degradation factors of halide-SE-based cathodes, which are different from the conventional findings of sulfide-SE-based cathodes. By using impedance decoupling combined with scanning spreading resistance microscopy and force spectroscopy, we elucidate the mechanisms behind the SE-dependent degradation of single-particle LiNi0.8Co0.1Mn0.1O2 (NCM) composite cathodes. Impedance analyses show that NCM-Li6PS5Cl (LPSCl) and NCM-Li3InCl6 (LIC) exhibit considerable increase in interfacial impedance and Li+-transport impedance, respectively, upon cycling. Based on the combined experimental and computational study of microscopic interfacial and mechanical properties, we demontrate that the degradation of NCM-LPSCl originates primarily from the formation of resistive interphases, while the crucial degradation factor of NCM-LIC is the cracking-induced mechanical deformation of the LIC under pressure. Finite element analysis results further reveal how the deformation behavior of the SE materials influences the formation and propagation of cracks in composite cathodes during cycling. This study provides insights into the design of materials and electrodes for ASSBs with high power capabilities and long cycle lifetimes. © 2023FALS

AgNO3-preplanted Li metal powder electrode: Preliminary formation of lithiophilic Ag and a Li3N-rich solid electrolyte interphase

Li metal powders (LMPs) are beneficial to fabricating thin and large-area Li electrodes for Li metal batteries (LMBs) owing to slurry coating-based manufacturing and facile impregnation of functional additives. 3D structure of LMP-based composites can alleviate the local current density even at a higher current. However, non-uniform nucleation and growth persist as barriers to guaranteeing both the performance and safety of LMBs. Here, we report an AgNO3-preplanted LMP electrode for securing long stable cycling of LMBs. During pre-mixing the LMP slurry with AgNO3 additive, it can chemically form lithiophilic Ag that can offer favorable nucleation sites throughout the LMP surface. At the same time, nitrates can help enrich a highly conductive, robust Li3N into solid electrolyte interphase (SEI). Pre-planting AgNO3 into a 40 μm-thick LMP electrode reinforced the cycling stability up to 500 cycles with 86.8 % capacity retention at 1C/3C charging/discharging rates and allowed superior rate capability up to 30C. © 2022 Elsevier B.V.FALS