Stable Photo-Rechargeable Al Battery for Enhancing Energy Utilization.

Photovoltaic cells (PVs) are able to convert solar energy to electric energy, while energy storage devices are required to be equipped due to the fluctuations of sunlight. However, the electrical connection of PVs and energy storage devices leads to increased energy consumption, and thus energy storage ability and utilization efficiency are decreased. One of the solutions is to explore an integrated photoelectrochemical energy conversion-storage device. Up to date, the integrated photo-rechargeable Li-ion batteries often suffer from unstable photo-active materials and flammable electrolytes under illumination, with concerns in safety risks and limited lifetime. To address the critical issues, here a novel photo-rechargeable aluminum battery (PRAB) is designed with safe ionic liquid electrolytes and stable polyaniline photo-electrodes. The integrated PRAB presents stable operation with an enhanced reversible specific capacity ≈191% under illumination. Meanwhile, a simplified continuum model is established to provide rational guidance for designing electrode structures along with a charging/discharging strategy to meet the practical operation conditions. The as-designed PRAB presents an energy-saving efficiency ≈61.92% upon charging and an energy output increment ≈31.25% during discharging under illumination. The strategy of designing and fabricating stable and safe photo-rechargeable non-aqueous Al batteries highlights the pathway for substantially promoting the utilization efficiency of solar energy.

Surface Engineering Based on Conductive Agent Dispersion Uniformity: Strategies toward Performance Consistency of Lithium-Ion Batteries.

The consistency of lithium-ion battery performance is the key factor affecting the safety and cycle life of battery packs. Surface engineering of electrodes in production processes plays an important role in improving the consistency of battery performance. In this study, the drying process in the electrode manufacturing process is studied as the effect on surface engineering of the electrode materials, with consideration on impacting the battery performance. Specifically, the solid content of the slurry and drying temperature are considered to be the two factors that affect conductive agent dispersion uniformity in the porous electrodes. To achieve surface engineering on the dispersion uniformity of the conductive agent, the optimal processing parameters can be obtained by adjusting the temperature and solid content of the slurry. The mechanism of dispersion uniformity of the conductive agent is mainly related to the polyvinylidene fluoride grid structure. In the manufacturing of lithium-ion batteries, the electrode coated with 66% solid slurry and dried at 90-100 °C presents stable energy storage performance, which is beneficial to maintain the stable performance of the battery pack in the application.

Construction of double reaction zones for long-life quasi-solid aluminum-ion batteries by realizing maximum electron transfer.

Achieving high energy density and long cycling life simultaneously remains the most critical challenge for aluminum-ion batteries (AIBs), especially for high-capacity conversion-type positive electrodes suffering from shuttle effect in strongly acidic electrolytes. Herein, we develop a layered quasi-solid AIBs system with double reaction zones (DRZs, Zone 1 and Zone 2) to address such issues. Zone 1 is designed to accelerate reaction kinetics by improving wetting ability of quasi-solid electrolyte to active materials. A composite three-dimensional conductive framework (Zone 2) interwoven by gel network for ion conduction and carbon nanotube network as electronic conductor, can fix the active materials dissolved from Zone 1 to allow for continuing electrochemical reactions. Therefore, a maximum electron transfer is realized for the conversion-type mateials in DRZs, and an ultrahigh capacity (400 mAh g-1) and an ultralong cycling life (4000 cycles) are achieved. Such strategy provides a new perspective for constructing high-energy-density and long-life AIBs.

Nickel-promoted Electrocatalytic Graphitization of Biochars for Energy Storage: Mechanistic Understanding using Multi-scale Approaches.

Owing to high-efficiency and scalable advantages of electrolysis in molten salts, electrochemical conversion of carbonaceous resources into graphitic products is a sustainable route for achieving high value-added carbon. To understand the complicated kinetics of converting amorphous carbon (e.g. carbonized lignin-biochar) into highly graphitic carbon, herein this study reports the key processing parameters (addition of Ni, temperature and time) and multi-scale approach of nickel-boosted electrochemical graphitization-catalysis processes in molten calcium chloride. Upon both experiments and modellings, multi-scale analysis that ranges from nanoscale atomic reaction to macroscale cell reveal the multi-field evolution in the electrolysis cell, mechanism of electrochemical reaction kinetics as well as pathway of nickel-boosted graphitization and tubulization. The results of as-achieved controllable processing regions and multi-scale approaches provide a rational strategy of manipulating electrochemical graphitization processes and utilizing the converted biomass resources for high value-added use.

High-Purity Graphitic Carbon for Energy Storage: Sustainable Electrochemical Conversion from Petroleum Coke.

The petroleum coke (PC) has been widely used as raw materials for the preparation of electrodes in aluminium electrolysis and lithium-ion batteries (LIB), during which massive CO2 gases are produced. To meet global CO2 reduction, an environmentally friendly route for utilizing PC is highly required. Here, a simple, scalable, catalyst-free process that can directly convert high-sulfur PC into graphitic nanomaterials under cathodic polarization in molten CaCl2 -LiCl at mild temperatures is proposed. The energy consumption of the proposed process is calculated to be 3 627.08 kWh t-1 , half that of the traditional graphitization process (≈7,825.21 kWh t-1 graphite). When applied as a negative electrode for LIBs, the as-converted graphite materials deliver a competitive specific capacity of ≈360 mAh g-1 (0.2 C) compared with commercial graphite. This approach has great potential to scale up for sustainably converting low-value PC into high-quality graphite for energy storage.

Single-Particle Measurements: A Powerful Method for Investigating Electrochemical Reactions.

The relationship between interface structure (e. g., the facet of the solid phase and the configuration of solvation) and the reactivity of the corresponding electrode is a critical issue in electrochemistry. Compared to macroscopic electrode measurements, electrochemical methods established on the single-particle scale have advantages in establishing the structure-property relationship. In recent years, great achievements have been made in electrochemical energy storage and electrocatalysis that allow the evolution and kinetics of electrodes to be understood by employing single-particle measurements. This concept aims to provide an overview of the update of single-particle measurements in related electrochemical processes. Furthermore, the challenges and prospects for the development and application of single-particle measurements are also discussed.

The Negative-Charge-Triggered "Dead Zone" between Electrode and Current Collector Realizes Ultralong Cycle Life of Aluminum-Ion Batteries.

Typically, volume expansion of the electrodes after intercalation of active ions is highly undesirable yet inetvitable, and it can significantly reduce the adhesion force between the electrodes and current collectors. Especially in aluminum-ion batteries (AIBs), the intercalation of large-sized AlCl4 - can greatly weaken this adhesion force and result in the detachment of the electrodes from the current collectors, which seems an inherent and irreconcilable problem. Here, an interesting concept, the "dead zone", is presented to overcome the above challenge. By incorporating a large number of OH- and COOH- groups onto the surface of MXene film, a rich negative-charge region is formed on its surface. When used as the current collector for AIBs, it shields a tiny area of the positive electrode (adjacent to the current collector side) from AlCl4 - intercalation due to the repulsion force, and a tiny inert layer (dead zone) at the interface of the positive electrode is formed, preventing the electrode from falling off the current collector. This helps to effectively increase the battery's cycle life to as high as 50 000 times. It is believed that the proposed concept can be an important reference for future development of current collectors in rocking chair batteries.

Toward Stable Al Negative Electrodes of Aluminum-Ion Batteries: Kinetic Parameters and Electrode Structure.

Rechargeable aluminum-ion batteries have attracted significant attention as candidates for next-generation energy storage devices owing to their high theoretical capacity, safe performance, and abundance of raw materials. Al metal is the best option as the negative electrode, while its issues such as dendrite growth and corrosion accompanying hydrogen evolution in ionic liquid electrolyte have been seriously overlooked. Understanding the electrochemical mechanism of the surface evolution behavior of Al metal is a vital pathway for solving these issues. Kinetic parameters and electrode structure are the two key parameters that affect the surface evolution behavior of Al negative electrodes. Herein, the qualitative relationship between the kinetic parameters and surface evolution behavior of the Al negative electrode was established through a combination of in-situ optical technology and multi-physical field numerical simulation method. The key kinetic parameters, including ion concentration and transfer coefficient, exhibited different laws of influence on the surface evolution behavior, such as dendrite growth and corrosion. The electrochemical mechanism on the surface evolution was explored to guide the optimization design of Al-ion batteries. Based on the coupling design of the electrode structure and kinetic parameters, a highly stable porous aluminum structure composed of Al powder with a particle size of 100 µm was constructed to obtain highly stable and high-performance aluminum-ion batteries. This method provides new sight into the design of high-performance aluminum-ion batteries.

Clinical observation of magnesium aluminum carbonate combined with rabeprazole-based triple therapy in the treatment of helicobacter pylori-positive gastric ulcer associated with hemorrhage.

Objectives: To evaluate the clinical effect of magnesium aluminum carbonate combined with rabeprazole-based triple therapy in the treatment of patients with Helicobacter pylori-positive gastric ulcer associated with hemorrhage. Methods: A total of 80 patients with Helicobacter pylori-positive gastric ulcer associated with hemorrhage admitted to the Baoding First Central Hospital from January 2019 to December 2020 were selected and randomly divided into two groups, with 40 cases in each group. The control group were given rabeprazole-based triple therapy, while the experimental group were treated with magnesium aluminum carbonate on the basis of the control group. The changes of symptoms and signs such as abdominal pain, abdominal distension, nausea, vomiting and hematochezia were compared between the two groups before and after treatment. Serological changes of the gastric mucosal microenvironment, such as the serum levels of extracellular regulatory protein kinase (ERK), superoxide dismutase (SOD) and epidermal growth factor receptor (EGFR), were compared between the two groups. Moreover, the differences in the results of gastroscopy between the two groups before and after treatment were compared and analyzed. Results: The scores of gastrointestinal symptoms in the experimental group after treatment were significantly improved compared with the control group (p=0.00). The levels of ERK and EGFR in the experimental group were significantly lower than those in the control group (ERK, p=0.01; EGRF, p=0.00), while the level of SOD was significantly increased (p=0.02). After treatment, the total effective rate of ulcer healing in the experimental group was 82.5%, which was significantly better than 60% in the control group (p=0.03). After treatment, moderate to severe gastric mucosal inflammation in the experimental group decreased to 10%, significantly better than that in the control group (decreased to 30%) (p=0.03). Conclusion: Magnesium aluminum carbonate combined with rabeprazole-based triple therapy is preferred for the treatment of patients with Helicobacter pylori-positive gastric ulcer associated with hemorrhage. With such a highly effective treatment regimen, the internal environment and blood supply of gastric mucosal cells can be significantly improved, gastric mucosal inflammation and gastrointestinal symptoms can be ameliorated, and the healing of ulcer surfaces can be accelerated.

Correlating Electrochemical Kinetic Parameters of Single LiNi1/3 Mn1/3 Co1/3 O2 Particles with the Performance of Corresponding Porous Electrodes.

Characterizing microscale single particles directly is requested for dissecting the performance-limiting factors at the electrode scale. In this work, we build a single-particle electrochemical setup and develop a physics-based model for extracting the solid-phase diffusion coefficient (Ds ) and exchange current density (i0 ) from electrochemical impedance measurements. We find that the carbon coating on the LiNi1/3 Mn1/3 Co1/3 O2 surface enhances i0 . In addition, Ds and i0 decay irreversibly by ≈25 % and ≈10 %, respectively, when the cutoff charge voltage increases from 4.3 V to 4.4 V. Moreover, we correlate intrinsic parameters of single particles with the performance of porous electrodes. Porous electrodes assembled with active particles with higher i0 values deliver a greater capacity and faster capacity fade. The methods developed in this combined experimental and theoretical work can be useful in correlating the single-particle scale and porous-electrode scale for other similar systems.

Understanding Enhanced Ionic Conductivity in Composite Solid-State Electrolyte in a Wide Frequency Range of 10-2 -1010 Hz.

The ionic conductivity of composite solid-state electrolytes (SSEs) can be tuned by introducing inorganic fillers, of which the mechanism remains elusive. Herein, ion conductivity of composite SSEs is characterized in an unprecedentedly wide frequency range of 10-2 -1010  Hz by combining chronoamperometry, electrochemical impedance spectrum, and dielectric spectrum. Using this method, it is unraveled that how the volume fraction v and surface fluorine content xF of TiO2 fillers tune the ionic conductivity of composite SSEs. It is identified that activation energy Ea is more important than carrier concentration c in this game. Specifically, c increases with v while Ea has the minimum value at v = 10% and increases at larger v. Moreover, Ea is further correlated with the dielectric constant of the SSE via the Marcus theory. A conductivity of 3.1×10-5 S cm-1 is obtained at 30 °C by tuning v and xF , which is 15 times higher than that of the original SSE. The present method can be used to understand ion conduction in various SSEs for solid-state batteries.

Electrocatalysis for Continuous Multi-Step Reactions in Quasi-Solid-State Electrolytes Towards High-Energy and Long-Life Aluminum-Sulfur Batteries.

Aluminum-sulfur (Al-S) batteries of ultrahigh energy-to-price ratios are a promising energy storage technology, while they suffer from a large voltage gap and short lifespan. Herein, we propose an electrocatalyst-boosting quasi-solid-state Al-S battery, which involves a sulfur-anchored cobalt/nitrogen co-doped graphene (S@CoNG) positive electrode and an ionic-liquid-impregnated metal-organic framework (IL@MOF) electrolyte. The Co-N4 sites in CoNG continuously catalyze the breaking of Al-Cl and S-S bonds and accelerate the sulfur conversion, endowing the Al-S battery with a shortened voltage gap of 0.43 V and a high discharge voltage plateau of 0.9 V. In the quasi-solid-state IL@MOF electrolytes, the shuttle effect of polysulfides has been inhibited, which stabilizes the reversible sulfur reaction, enabling the Al-S battery to deliver 820 mAh g-1 specific capacity and 78 % capacity retention after 300 cycles. This finding offers novel insights to design Al-S batteries for stable energy storage.

A 4D x-ray computer microtomography for high-temperature electrochemistry.

High-temperature electrochemistry is widely used in many fields. However, real-time observations and an in-depth understanding of the inside evolution of this system from an experimental perspective remain limited because of harsh reaction conditions and multiphysics fields. Here, we tackled this challenge with a high-temperature electrolysis facility developed in-house. This facility permits in situ x-ray computer microtomography (µ-CT) for nondestructive and quantitative three-dimensional (3D) imaging. In an electrorefining system, the µ-CT probed the dynamic evolution of 3D morphology and components of electrodes (4D). Subsequently, this 4D process was visually presented via reconstructed images. The results monitor the efficiency of the process, explore the dynamic mechanisms, and even offer real-time optimization. This 4D analysis platform is notable for in-depth combinations of traditional electrochemistry with digital twin technologies owing to its multiscale visualization and high efficiency of data extraction.

Stable Quasi-Solid-State Aluminum Batteries.

Nonaqueous rechargeable aluminum batteries (RABs) of low cost and high safety are promising for next-generation energy storage. With the presence of ionic liquid (IL) electrolytes, their high moisture sensitivity and poor stability would lead to critical issues in liquid RABs, including undesirable gas production, irreversible activity loss, and an unstable electrode interface, undermining the operation stability. To address such issues, herein, a stable quasi-solid-state electrolyte is developed via encapsulating a small amount of an IL into a metal-organic framework, which not only protects the IL from moisture, but creates sufficient ionic transport network between the active materials and the electrolyte. Owing to the generated stable states at both positive-electrode-electrolyte and negative-electrode-electrolyte interfaces, the as-assembled quasi-solid-state Al-graphite batteries deliver specific capacity of ≈75 mA h g-1 (with positive electrode material loading ≈9 mg cm-2 , much higher than that in the conventional liquid systems). The batteries present a long-term cycling stability beyond 2000 cycles, with great stability even upon exposure to air within 2 h and under flame combustion tests. Such technology opens a new platform of designing highly safe rechargeable Al batteries for stable energy storage.

Rechargeable Metasurfaces for Dynamic Color Display Based on a Compositional and Mechanical Dual-Altered Mechanism.

Dynamic color display can be realized by tunable optical metasurfaces based on the compositional or structural control. However, it is still a challenge to realize the efficient modulation by a single-field method. Here, we report a novel compositional and mechanical dual-altered rechargeable metasurface for reversible and broadband optical reconfiguration in both visible and near-infrared wavelength regions. By employing a simple fabrication and integration strategy, the continuous optical reconfiguration is manipulated through an electro-chemo-mechanical coupled process in a lithium ion battery, where lithiation and delithiation processes occur dynamically under a low electric voltage (≤1.5 V). By controlling the phase transformation from Si to Li xSi, both structural morphology and optical scattering could be rapidly and dramatically tailored within 30 s, exhibiting high-contrast colorization and decolorization in a large-area nanofilm and showing long cyclic stability. Significant wide-angle reconfiguration of high-resolution structural colors in bowtie metasurfaces is demonstrated from anomalous reflection. The results provide a multifield mechanism for reconfigurable photonic devices, and the new platform can be introduced to the multidimensional information encryption and storage.

3D printed metasurface for generating a Bessel beam with arbitrary focusing directions.

In this Letter, a metasurface combined with emerging 3D printing technology is proposed. The proposed metasurface regards the simple cube as the unit cell, and the height of the cube is the only variable. A nearly linear transmission phase range covering 360° operating at 20 GHz is obtained when the height is regulated in [2.26 mm, 11.20 mm]. Therefore, the proposed unit cell can be adopted to any metasurface with various functions. Taking the generation of a non-diffractive Bessel beam as an example, two metasurfaces composed of 30×30 units with different focusing directions are designed based on non-diffractive theory and the generalized law of refraction. Two prototypes are 3D printed and measured by a near-field scanning system. The measured results validate our design with satisfactory focusing and beam deflection performance. Additionally, the 3D printed metasurface has lower cost and a shorter processing cycle, and avoids metal loss. Therefore, a 3D printed metasurface is an excellent candidate that can be applied in millimeter wave or even higher frequency bands.

Quantificational 4D Visualization of Industrial Electrodeposition.

Electrodeposition is a fundamental technology in modern society and has been widely used in metal plating and extraction, etc. However, extreme reaction conditions, including wide operation temperature ranges and corrosive media (molten salt/oxide systems as a particular example), inhibit direct in situ observation of the electrodeposition process. To visualize the electrode kinetics in such "black box," X-ray tomography is employed to monitor the electrochemical processes and three-dimensional (3D) evolution of morphology. Benefiting from the excellent penetration of X-ray, a non-destructive and non-contact in situ four-dimensional (4D) visualization of Ti deposition is realized. Real-time 3D reconstructed images reveal that the counterintuitive nucleation and growth process of a mesoscale Ti dendrite at both solid and liquid cathodes. According to 3D morphology evolution, unusual mechanism based on synergetic effect of the diffusion of metallic Ti and local field enhancement is achieved utilizing a simulation method based on a finite element method. This approach allows for timely and accurately regulating the electrodeposition process upon in situ monitored parameters. More importantly, the 4D technique upon operando X-ray tomography and numerical simulation can be easily applied to other electrodeposition systems, which will help deeply understand the internal kinetics and the precise optimization of the electrodeposition conditions.

Bidirectional Planar Flexible Snake-Origami Batteries.

With the rapid development of commercial flexible/wearable devices, flexible batteries have attracted great attention as optimal power sources. However, a combination of high energy density and excellent arbitrary deformation ability is still a critical challenge to satisfy practical applications. Inspired by rigid and soft features of chemical molecular structures, novel bidirectional flexible snake-origami lithium-ion batteries (LIBs) with both high energy density and favorable flexibility are designed and fabricated. The flexible snake-origami battery consists of rigid and soft segments, where the former is designed as the energy unit and the latter served as the deformation unit. With the unique features from such design, the as-fabricated battery with calculating all the components exhibits a record-setting energy density of 357 Wh L-1 (133 Wh kg-1 ), compared with the cell-scale flexible LIBs achieved from both academic and industry. Additionally, a design principle is established to verify the validity of utilizing rigid-soft-coupled structure for enduring various deformations, and the intrinsic relationship between battery structure, energy density, and flexibility can be confirmed. The results suggest that the design principle and performance of bidirectional flexible snake-origami batteries will provide a new reliable strategy for achieving high energy flexible batteries for wearable devices.

A Review of Integrated Systems Based on Perovskite Solar Cells and Energy Storage Units: Fundamental, Progresses, Challenges, and Perspectives.

With the remarkable progress of photovoltaic technology, next-generation perovskite solar cells (PSCs) have drawn significant attention from both industry and academic community due to sustainable energy production. The single-junction-cell power conversion efficiency (PCE) of PSCs to date has reached up to 25.2%, which is competitive to that of commercial silicon-based solar cells. Currently, solar cells are considered as the individual devices for energy conversion, while a series connection with an energy storage device would largely undermine the energy utilization efficiency and peak power output of the entire system. For substantially addressing such critical issue, advanced technology based on photovoltaic energy conversion-storage integration appears as a promising strategy to achieve the goal. However, there are still great challenges in integrating and engineering between energy harvesting and storage devices. In this review, the state-of-the-art of representative integrated energy conversion-storage systems is initially summarized. The key parameters including configuration design and integration strategies are subsequently analyzed. According to recent progress, the efforts toward addressing the current challenges and critical issues are highlighted, with expectation of achieving practical integrated energy conversion-storage systems in the future.

A highly conductive self-assembled multilayer graphene nanosheet film for electronic tattoos in the applications of human electrophysiology and strain sensing.

Highly conductive, conformable and gel-free electrodes are desirable in human electrophysiology. Besides, intimately coupling with human skin, wearable strain sensors can detect numerous physiological signals, such as wrist pulse and breath. In this study, a multilayer graphene nanosheet film (MGNF) with high conductivity was prepared by the Marangoni self-assembly for using in tattoo dry electrodes (TDEs) and in a graphene tattoo strain sensor (GTSS). Compared to commercial Ag/AgCl gel electrodes, TDEs have lower skin-electrode contact impedance and could detect human electrocardiogram for 24-hour wearing more accurately as well as electromyogram. Through designing a slim serpentine ribbon structure, a resistance-type GTSS, without deterioration even after 2000 cycles, is well demonstrated for human wrist pulse and breath sensing. With the advantages of high conductivity and conformability, MGNF provides support to fabricate low-cost, customizable, and high-performance electronic tattoos for human electrophysiology and strain sensing.