Optogenetics refers to a technique that uses light to modulate neuronal activity with a high spatiotemporal resolution, which enables the manipulation of learning and memory functions in the human ...brain. This strategy of controlling neuronal activity using light can be applied for the development of intelligent systems, including neuromorphic and in‐memory computing systems. Herein, a flexible van der Waals (vdW) optoelectronic synapse is reported, which is a core component of optogenetics‐inspired intelligent systems. This synapse is fabricated on 2D vdW layered rhenium disulfide (ReS2) that features an inherent photosensitive memory nature derived from the persistent photoconductivity (PPC) effect, successfully mimicking the dynamics of biological synapses. Based on first‐principles calculations, the PPC effect is identified to originate from sulfur vacancies in ReS2 that have an inherent tendency to form shallow defect states near the conduction band edges and under optical excitation lead to large lattice relaxation. Finally, the feasibility of applying the synapses in optogenetics‐inspired intelligent systems is demonstrated via training and inference tasks for the CIFAR‐10 dataset using a convolutional neural network composed of vdW optoelectronic synapse devices.
A flexible van der Waals (vdW) optoelectronic synapse fabricated on 2D vdW layered rhenium disulfide, which features an inherent photosensitive memory nature derived from the persistent photoconductivity effect, is proposed. Following in‐depth analysis including density functional theory calculations on rhenium disulfide, its feasibility for hardware neural networks with learning ability is demonstrated using a convolutional neural network composed of vdW optoelectronic synapses.
The multiscale chemomechanical interplay in lithium‐ion batteries builds up mechanical stress, provokes morphological breakdown, and leads to state of charge heterogeneity. Quantifying the interplay ...in complex composite electrodes with multiscale resolution constitutes a frontier challenge in precisely diagnosing the fading mechanism of batteries. In this study, hard X‐ray phase contrast tomography, capable of nanoprobing thousands of active particles at once, enables an unprecedented statistical analysis of the chemomechanical transformation of composite electrodes under fast charging conditions. The damage heterogeneity is demonstrated to prevail at all length scales, which stems from the unbalanced electron conduction and ionic diffusion, and collectively leads to the nonuniform utilization of active particles spatially and temporally. This study highlights that the statistical mapping of the chemomechanical transformation offers a diagnostic method for the particles utilization and fading, hence could improve electrode formulation for fast‐charging batteries.
Hard X‐ray phase contrast tomography, capable of nano‐probing thousands of active particles at once, enables an unprecedented statistical analysis of the chemomechanical transformation of composite electrodes under fast charging conditions. This study offers a diagnosing method for the particles utilization and fading, hence could improve the electrode formulation for fast‐charging batteries.
Aqueous Zn‐ion battery is a promising technology for electrochemical energy storage. The formation of Zn dendrites, however, can jeopardize the cell cycle life and thus, hinders the industrial ...adoption of this technology. A fundamental understanding of the kinetic mechanisms is crucial for improving the Zn‐ion battery. Here, in situ and operando X‐ray microscopy methods are utilized to visualize the Zn plating and stripping behaviors under different electrochemical conditions. It is demonstrated that the substrate curvature, local morphology, electrochemical protocols, and the surface chemistry can collectively affect the Zn plating behavior. These results provide new insights for developing the next‐generation dendrite‐free and long‐span aqueous Zn‐ion battery.
Zn plating/stripping process is investigated using in situ X‐ray imaging techniques. The results suggest that initial Zn nucleation has a strong dependence on the substrate‐local‐curvature. The reaction heterogeneities under different current densities are quantified by analyzing the three‐dimensional tomography. The surface properties of the Cu substrate can be affected by ZnSO4 electrolyte, leading to distinguish Zn plating behaviors.
Nickel hydroxide represents a technologically important material for energy storage, such as hybrid supercapacitors. It has two different crystallographic polymorphs, α‐ and β‐Ni(OH)2, showing ...advantages in either theoretical capacity or cycling/rate performance, manifesting a trade‐off trend that needs to be optimized for practical applications. Here, the synergistic superiorities in both activity and stability of corrugated β‐Ni(OH)2 nanosheets are demonstrated through an electrochemical abuse approach. With ≈91% capacity retention after 10 000 cycles, the corrugated β‐Ni(OH)2 nanosheets can deliver a gravimetric capacity of 457 C g−1 at a high current density of 30 A g−1, which is nearly two and four times that of the regular α‐ and β‐Ni(OH)2, respectively. Operando spectroscopy and finite element analysis reveal that greatly enhanced chemical activity and structural robustness can be attributed to the in situ tailored lattice defects and the strain‐induced highly curved micromorphology. This work demonstrates a multi‐scale defect‐and‐strain co‐design strategy, which is helpful for rational design and tuned fabrication of next‐generation electrode materials for stable and high‐rate energy storage.
Corrugated β‐Ni(OH)2, with outstanding activity and stability for hybrid supercapacitors, is developed through an electrochemical abuse strategy. The operando X‐ray absorption fine structure technique and finite‐element analysis demonstrate that the in‐situ‐tailored lattice defects and the strain‐induced highly curved micromorphology play critical roles in enhancing chemical activity and structural robustness.
Abstract
Surface lattice reconstruction is commonly observed in nickel-rich layered oxide battery cathode materials, causing unsatisfactory high-voltage cycling performance. However, the interplay of ...the surface chemistry and the bulk microstructure remains largely unexplored due to the intrinsic structural complexity and the lack of integrated diagnostic tools for a thorough investigation at complementary length scales. Herein, by combining nano-resolution X-ray probes in both soft and hard X-ray regimes, we demonstrate correlative surface chemical mapping and bulk microstructure imaging over a single charged LiNi
0.8
Mn
0.1
Co
0.1
O
2
(NMC811) secondary particle. We reveal that the sub-particle regions with more micro cracks are associated with more severe surface degradation. A mechanism of mutual modulation between the surface chemistry and the bulk microstructure is formulated based on our experimental observations and finite element modeling. Such a surface-to-bulk reaction coupling effect is fundamentally important for the design of the next generation battery cathode materials.
Understanding the behavior of lithium‐ion batteries (LIBs) under extreme conditions, for example, low temperature, is key to broad adoption of LIBs in various application scenarios. LIBs, poor ...performance at low temperatures is often attributed to the inferior lithium‐ion transport in the electrolyte, which has motivated new electrolyte development as well as the battery preheating approach that is popular in electric vehicles. A significant irrevocable capacity loss, however, is not resolved by these measures nor well understood. Herein, multiphase, multiscale chemomechanical behaviors in composite LiNixMnyCozO2 (NMC, x + y + z = 1) cathodes at extremely low temperatures are systematically elucidated. The low‐temperature storage of LIBs can result in irreversible structural damage in active electrodes, which can negatively impact the subsequent battery cycling performance at ambient temperature. Beside developing electrolytes that have stable performance, designing batteries for use in a wide temperature range also calls for the development of electrode components that are structurally and morphologically robust when the cell is switched between different temperatures.
A holistic experimental approach is adopted to systematically elucidate the multiphase, multiscale chemomechanical behaviors in LIB cathodes at extremely low temperatures. The results suggest that, in order to design batteries for use in a wide temperature range, it is critical to develop electrode components that are structurally and morphologically robust when the cell is switched between different temperatures.
Single-crystalline nickel-rich cathodes are a rising candidate with great potential for high-energy lithium-ion batteries due to their superior structural and chemical robustness in comparison with ...polycrystalline counterparts. Within the single-crystalline cathode materials, the lattice strain and defects have significant impacts on the intercalation chemistry and, therefore, play a key role in determining the macroscopic electrochemical performance. Guided by our predictive theoretical model, we have systematically evaluated the effectiveness of regaining lost capacity by modulating the lattice deformation via an energy-efficient thermal treatment at different chemical states. We demonstrate that the lattice structure recoverability is highly dependent on both the cathode composition and the state of charge, providing clues to relieving the fatigued cathode crystal for sustainable lithium-ion batteries.
The globalisation of the food industry increases the complexity and the difficulty in enhancing efficiency and solving issues in food supply chains. Blockchain is a promising decentralised ...information technology that could benefit food supply chains by reducing transaction cost and time, increasing process transparency, security, and efficiency, as well as building trust among participants. In this paper, we introduce the major blockchain platforms currently used in food supply chains and conduct a synthesis analysis to explore the benefits and challenges of blockchain technology in the food industry. We demonstrate that blockchain enables unprecedented visibility at each step of the food supply chain, helps increase transaction transparency, food safety, and quality, and also reduces food fraud and waste. Furthermore, it serves as a digital solution for reducing operational costs and improving efficiency in food supply chains.
Lithium-rich nickel-manganese-cobalt (LirNMC) layered material is a promising cathode for lithium-ion batteries thanks to its large energy density enabled by coexisting cation and anion redox ...activities. It however suffers from a voltage decay upon cycling, urging for an in-depth understanding of the particle-level structure and chemical complexity. In this work, we investigate the Li
Ni
Mn
Co
O
particles morphologically, compositionally, and chemically in three-dimensions. While the composition is generally uniform throughout the particle, the charging induces a strong depth dependency in transition metal valence. Such a valence stratification phenomenon is attributed to the nature of oxygen redox which is very likely mostly associated with Mn. The depth-dependent chemistry could be modulated by the particles' core-multi-shell morphology, suggesting a structural-chemical interplay. These findings highlight the possibility of introducing a chemical gradient to address the oxygen-loss-induced voltage fade in LirNMC layered materials.
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