Collection: Electrochemical Energy Storage and Conversion
Review of modification strategies in emerging inorganic solid-state electrolytes for lithium, sodium, and potassium batteries
All-solid-state batteries (ASSBs) based on solid-state electrolytes (SSEs) offer the possibility of a much safer operation without the risk of fires or explosions. However, despite years of intensive research, there is not one ASSB that can simultaneously meet the fast charge and extended cyclability requirements of a modern automotive lithium-ion battery. This topical review focuses the most promising lithium-, sodium-, and emerging potassium-based SSEs. The discussion spans the fundamental science of structural stability, ion conductivity, and interface degradation behavior.Solid-state lithium battery cathodes operating at low pressures
A solid-state composite cathode comprises particles of cathode active materials, solid electrolytes, and often carbon. Here, we show that the capacity depends primarily on the ion transport through the solid electrolyte within the composite cathode. The capacity fades on cycling due to the volume changes of the active materials, which is much more significant at lower pressures. This work suggests solutions to achieve and maintain the high capacity at high rates and low pressures.Research priorities for seasonal energy storage using electrolyzers and fuel cells
Seasonal storage of energy may be required for grids reliant on intermittent resources such as solar and wind and could be accomplished through the underground storage of hydrogen gas. Through a technoeconomic analysis of charging and discharging systems, we summarize electrochemistry research priorities that would enable electrolyzers and fuel cells to be used for seasonal energy storage.Liquid electrolyte: The nexus of practical lithium metal batteries
Li metal batteries have great potential in enhancing the energy density of next-generation battery systems used for electric vehicles and grid storage, but they have been plagued by their poor cyclability. Liquid electrolyte engineering has demonstrated its promises in Li metal battery cycling performances. Here, we summarize past designs of Li metal battery electrolytes, conclude their common features, and propose detailed design principles for further investigations.Neutron imaging of lithium batteries
Developments in neutron imaging techniques over the past decade provide a compelling characterization technique for Li batteries. The high sensitivity to low-Z elements provides the ideal probe for tracking Li-diffusion processes, electrolyte consumption, or filling in two to four dimensions with micrometer resolution. The excellent scattering properties of neutrons allow the investigation of crystallographic phase changes with resolutions down to a few hundred microns. This article summarizes key recent works and future perspectives on neutron imaging techniques in the field of battery characterization.“Soft Shorts” Hidden in Zinc Metal Anode Research
Substantial discrepancies exist between symmetric cells and full cells in terms of their applied current densities and accumulative stripping and plating capacities, indicating a possible hidden mechanism in symmetric cells that induces the misjudgment of Zn stability. This commentary examines the often-overlooked soft short phenomenon in symmetric cells and exemplifies how its dynamic nature convolutes the evaluation of Zn anode stability. Accordingly, two pertinent test protocols were proposed to assess symmetric cells and characterize the genuine stability of Zn anodes.Asymmetric donor-acceptor molecule-regulated core-shell-solvation electrolyte for high-voltage aqueous batteries
Asymmetric donor-acceptor molecules such as methylurea can regulate the hydrogen-bonding network of aqueous electrolyte to form a peculiar nanoscale core-shell-like solvation structure, which not only breaks the physical restriction of limited lithium salt solubility in water but also effectively suppresses hydrogen evolution at low potentials toward 0.5 V versus Li+/Li. This simple approach truly inherits the high safety of aqueous electrolytes and substantially expands the electrochemical stability window without compromising its cost-effective property.Nonaqueous rechargeable aluminum batteries
Demands for affordable, sustainable, and performant energy storage technologies have stimulated increased interests in rechargeable Al batteries (RABs). However, initial enthusiasm and high expectations should now be replaced by a more measured period of research that critically assesses several fundamental aspects of RABs. In this work, we summarized, discussed, and assessed the charge storage mechanisms, the impact of cell chemistries on battery performance metrics, solid-state ion migration, and advanced techniques that can further deepen our understandings of existing RAB chemistries.Singlet oxygen and dioxygen bond cleavage in the aprotic lithium-oxygen battery
The cathode reaction on discharge is the reduction of O2 to Li2O2 via the intermediate LiO2. We show that disproportionation is the dominant route of Li2O2 formation, not the direct reduction of LiO2. Using a mixture of 18O18O and 16O16O gases, we demonstrate that a proportion of LiO2 disproportionation involves O–O bond cleavage and that a relatively high proportion of such cleavage leads to singlet O2, which has been implicated in degradation. The results suggest options for suppressing degradation.Toward high-energy Mn-based disordered-rocksalt Li-ion cathodes
Mn-based disordered-rocksalt compounds (Mn-DRX) represent promising Co-free cathode materials for high-energy, sustainable Li-ion batteries. Yet, significant challenges prevent their practical use, such as slow-cycling kinetics and poor capacity retention. By providing an in-depth analysis of the materials’ kinetic properties, redox/degradation mechanisms, and synthesis methods, this review provides targeted guidance for the future collective efforts of the research community to make progress toward Mn-DRX cathodes with fast rate capability, long cycle life, and high practical energy density at the electrode-film level.Predicting battery end of life from solar off-grid system field data using machine learning
Off-grid solar-battery systems provide clean electricity, enabling education and enterprise. However, these systems are in remote areas, and it can be difficult to replace failed batteries. To improve reliability and cost-effectiveness, a non-invasive method to estimate battery health is required. We demonstrate how real-world operating data may be used to infer health and detect end of life. This work highlights the opportunity to analyze field data with machine learning to understand battery aging.Storing energy with molecular photoisomers
Harvesting solar energy with molecular photoisomers can be an attractive way for the development of cleaner energy resources. Molecular solar thermal energy storage (MOST) is a concept based on molecular photoswitches, which allow sunlight to be stored and released as heat on demand. In this review, we introduce the concept and state-of-the-art, focusing on chemical engineering efforts, existing challenges, and future design strategies for a better solar energy storage performance.Rechargeable aqueous Zn-based energy storage devices
Since the emergence of the first electrochemical energy storage device in 1799, over 50 different types of aqueous Zn-based EES devices (AZDs) have been proposed and studied. This work adopts a holistic perspective to review all types of key devices and representative AZDs. Here, we summarized and discussed the fundamental charge storage mechanisms, interface properties, promising strategies for key components, innovation in cell configuration, and the state-of-art devices for high-capacity, (ultra)high power density, and high energy density applications.Bayesian learning for rapid prediction of lithium-ion battery-cycling protocols
Developing advanced lithium-ion batteries requires optimizing performance across parameter spaces with extremely high dimensionality, long testing times, and high variability between cells, particularly in early development. A machine learning methodology is developed for accelerating the design of cycling protocols, with reduced experimental costs of testing time and cells, by providing accurate evaluation of cycling protocols using very few cycles and cells.Predicting the impact of formation protocols on battery lifetime immediately after manufacturing
Manufacturing is an integral part of the cost and environmental footprint of batteries. An inexpensive and rapid diagnostic signal was found that can guide improvements in the manufacturing process. The signal can resolve differences in lithium consumed during battery formation and can be used to diagnose the impact of process changes on the lifetime of the battery.The case for fluoride-ion batteries
Fluoride-ion batteries (FIBs) are a promising technology for next-generation batteries because of their high theoretical energy density and utilization of highly abundant and relatively inexpensive materials. In this perspective, we perform a techno-economic analysis to highlight the potential advantages of some FIB configurations over state-of-the-art lithium-ion batteries and high-energy-density lithium-metal-based chemistries. Additionally, we prescribe three critical research fronts that should be addressed in order for FIBs to become a viable technology.Recycled cathode materials enabled superior performance for lithium-ion batteries
Based on our closed-loop recycling process, recycled NMC111 with unique microstructure has a superior rate and cycle performance, verified by various industry-level tests. Recycled materials’ unique void/pore-rich structure provides a higher Li chemical diffusion coefficient and better strain mitigation during cycling, leading to fewer cracks. Thus, our work offers a green and sustainable solution for spent lithium-ion batteries, eliminates industry doubts on the performance of recycled materials, paves the way for lithium-ion battery recycling commercialization, and builds a bridge between industry and academia.Intrinsic voltage plateau of a Nb2CTx MXene cathode in an aqueous electrolyte induced by high-voltage scanning
In the past decade, two-dimensional MXenes have been a rising star in the energy storage field, featured by fast surficial redox and high-rate energy storage. However, typically, MXene electrodes exhibit capacitive behavior with a rapidly descending output voltage during discharge. Moreover, the absence of distinct voltage plateaus deteriorates their capacities and energy densities. Our work outlines an efficient route toward achieving high-energy-density MXene electrodes with distinct discharge voltage plateau through a high-voltage-scanning approach.Low-cost manganese dioxide semi-solid electrode for flow batteries
Flow batteries are advantageous for long-duration energy storage. This paper identifies the technical and economic feasibility of MnO2 semi-solid electrode for flow batteries through electrochemical and rheological experiments, and cost modeling. Despite the low chemical cost, MnO2 semi-solid electrode can incur high costs for power components such as the pump. Our holistic approach enabled us to identify the strategies to minimize the increase in the cost of power because the pumping requirements of the viscoplastic pasty MnO2 semi-solid electrode. We found that an optimized Zn-MnO2 semi-solid flow battery can be cost-competitive for discharge durations longer than a day.The role of artificial intelligence in the mass adoption of electric vehicles
The mass adoption of electric transportation is considered crucial to curtail greenhouse-gas emissions. Although electric vehicles (EVs) have been steadily penetrating the vehicle market over the last decade, EVs and their supporting infrastructure suffer from challenges, which include short driving range and lack of relevant charging infrastructures. This review explores the areas where artificial intelligence (AI)—within EVs themselves, EV-charging stations, and the interaction of EVs with renewable generation systems—can be used to overcome these challenges.Stress evolution during cycling of alloy-anode solid-state batteries
Control over the interplay between electrochemical reactions and the mechanical behavior of solid-state batteries is critical to improve performance. This study links the electrochemical behavior of alloy-anode-based solid-state batteries to stack pressure during charge and discharge, showing that the electrode architecture and active material have strong effects on stack pressure variations. Furthermore, all-solid-state batteries with alloy anodes show promising long-term cycling performance and exhibit stable megapascal-level stack pressure changes during cycling.Photopatternable hydroxide ion electrolyte for solid-state micro-supercapacitors
One potential direction for achieving better integration with miniaturized electronics is to develop a photopatternable electrochemical energy storage system. To meet this objective, a photopatternable hydroxide-conducting electrolyte was developed via covalent grafting of polymerizable cations onto photopatternable polymer hosts, followed by anion exchange to incorporate hydroxides. The resulting solid electrolyte is thermally and dimensionally stable and has high hydroxide ion conductivity. For device integration, the hydroxide-conducting solid electrolyte was directly patterned onto vanadium nitride micro-supercapacitor electrodes.Ultrastable aqueous phenazine flow batteries with high capacity operated at elevated temperatures
This work reports a high-capacity aqueous organic redox-flow battery (AORFB) that can be operated at elevated temperature with no capacity fade. The chemical and electrochemical properties of the energy-storage materials are carefully modulated through effective molecular design. The developed AORFB presented in this work potentially enables robust stationary electrical energy storage in high temperature areas with abundant solar energy for real-world application.Dual-anion ionic liquid electrolyte enables stable Ni-rich cathodes in lithium-metal batteries
Exploiting the high-energy density of lithium metal as a negative electrode for lithium batteries is considered a prerequisite to satisfy the continually increasing demand for extended driving range of electric vehicles and fully electrify our mobility and transportation. However, such lithium-metal batteries face critical safety and life-span concerns. This work outlines a clear route toward realizing safe high-energy-density lithium-metal batteries with excellent cycling stability through the use of a non-flammable and low-volatile ionic liquid electrolyte.Operando spatial mapping of lithium concentration using thermal-wave sensing
A thermal-wave sensing method is proposed to measure spatially resolved through-plane Li concentration in the electrodes. We demonstrate that thermal-wave sensing provides spatial information of lithium concentration comparable with experimental results using synchrotron X-ray diffraction.
