as smartphones, electric vehicles, and energy storage systems depend on LIBs to provide the necessary power for optimal performance. Today, that dependency continues to grow at an exponential rate as the portfolio of electronic devices and vehicles diversifies. The common denominator for the myriad of commercialized devices is the constant demand for high power and long usage time. Accordingly, the frontrunners of today's technology are striving to optimize LIBs to meet such performance demands. While such efforts have extended the usage time of various devices, this direction has also exposed critical issues with current battery technology: safety and cost.The main cause for safety hazards with LIBs is linked to the use of organic electrolytes. In the unfortunate event of a short circuit in a battery, a sudden burst of exothermic reactions is accelerated by the presence of organic solvents, which act as fuel for ensuing fires. This problem is exacerbated in high energy density configurations where materials are densely packed. The risk of fire hazards has prompted a search for alternative battery systems, among which rechargeable aqueous batteries have garnered significant attention as viable candidates for safe batteries. Replacing the organic solvent with water as the electrolyte medium has significant implications. In addition to the benefit of heightened safety, water has a high ionic conductivity compared to conventional organic solvents (2-3 orders of magnitude higher), a useful quality for high C-rate operations. Moreover, the use of water can reduce costs incurred from moisture regulation during manufacturing.Unfortunately, despite these attractive aspects, aqueous electrolytes impose certain barriers. Most critically, the thermodynamic stability window of water is limited to 1.23 V, beyond which detrimental hydrogen and oxygen evolution reactions (HER/OER) occur. As a result, even if kinetic overpotentials are taken into account, the operating potential windows of aqueous batteries are significantly narrower than those of their organic counterparts. This motivates the search for adequate materials that provide maximum energy within such a narrow voltage window. The prevalent layered oxide/graphite system used in conventional LIBs is no longer an option in this system due to such voltage constraints. Instead, on the anode side, zinc (Zn) metal is considered to be a promising candidate. [1] Not only is Zn abundant in nature, nontoxic, and cheap, but its metallic Aqueous zinc ion batteries (AZIBs) are steadily gaining attention based on their attractive merits regarding cost and safety. However, there are many obstacles to overcome, especially in terms of finding suitable cathode materials and elucidating their reaction mechanisms. Here, a mixed-valence vanadium oxide, V 6 O 13 , that functions as a stable cathode material in mildly acidic aqueous electrolytes is reported. Paired with a zinc metal anode, this material exhibits performance metrics of 360 mAh g −1 at 0.2 A g −1 , 92% capacity retention after...

Li-ion batteries have revolutionized the portable electronics industry and empowered the electric vehicle (EV) revolution. Unfortunately, traditional Li-ion chemistry is approaching its physicochemical limit. The demand for higher density (longer range), high power (fast charging), and safer EVs has recently created a resurgence of interest in solid state batteries (SSB). Historically, research has focused on improving the ionic conductivity of solid electrolytes, yet ceramic solids now deliver sufficient ionic conductivity. The barriers lie within the interfaces between the electrolyte and the two electrodes, in the mechanical properties throughout the device, and in processing scalability. In 2017 the Faraday Institution, the UK’s independent institute for electrochemical energy storage research, launched the SOLBAT (solid-state lithium metal anode battery) project, aimed at understanding the fundamental science underpinning the problems of SSBs, and recognising that the paucity of such understanding is the major barrier to progress. The purpose of this Roadmap is to present an overview of the fundamental challenges impeding the development of SSBs, the advances in science and technology necessary to understand the underlying science, and the multidisciplinary approach being taken by SOLBAT researchers in facing these challenges. It is our hope that this Roadmap will guide academia, industry, and funding agencies towards the further development of these batteries in the future.

The intrinsic limitations of lithium-ion batteries (LIBs) with regard to safety, cost, and the availability of raw materials have promoted research on so-called "post-LIBs". The recent intense research of post-LIBs provides an invaluable lesson that existing electrode materials used in LIBs may not perform as well in post-LIBs, calling for new material designs compliant with emerging batteries based on new chemistries. One promising approach in this direction is the development of materials with intercalated water or organic molecules, as these materials demonstrate superior electrochemical performance in emerging battery systems. The enlarged ionic channel dimensions and effective shielding of the electrostatic interaction between carrier ions and the lattice host are the origins of the observed electrochemical performance. Moreover, these intercalants serve as interlayer pillars to sustain the framework for prolonged cycles. Representative examples of such intercalated materials applied to batteries based on Li , Na , Mg , and Zn ions and supercapacitors are considered, along with their impact in materials research.

Solid-state batteries (SSBs) have received attention as a next-generation energy storage technology due to their potential to superior deliver energy density and safety compared to commercial Li-ion batteries. One of the main challenges limiting their practical implementation is the rapid capacity decay caused by the loss of contact between the cathode active material and the solid electrolyte upon cycling. Here, we use the promising high-voltage, low-cost LiNi0.5Mn1.5O4 (LNMO) as a model system to demonstrate the importance of the cathode microstructure in SSBs. We design Al2O3-coated LNMO particles with a hollow microstructure aimed at suppressing electrolyte decomposition, minimizing volume change during cycling, and shortening the Li diffusion pathway to achieve maximum cathode utilization. When cycled with a Li6PS5Cl solid electrolyte, we demonstrate a capacity retention above 70% after 100 cycles, with an active material loading of 27 mg cm–2 (2.2 mAh cm–2) at a current density of 0.8 mA cm–2.