Anode-Free Sodium Battery through in Situ Plating of Sodium Metal

Sodium-ion batteries (SIBs) have been pursued as a more cost-effective and more sustainable alternative to lithium-ion batteries (LIBs), but these advantages come at the expense of energy density. In this work, we demonstrate that the challenge of energy density for sodium chemistries can be overcome through an anode-free architecture enabled by the use of a nanocarbon nucleation layer formed on Al current collectors. Electrochemical studies show this configuration to provide highly stable and efficient plating and stripping of sodium metal over a range of currents up to 4 mA/cm², sodium loading up to 12 mAh/cm², and with long-term durability exceeding 1000 cycles at a current of 0.5 mA/cm². Building upon this anode-free architecture, we demonstrate a full cell using a presodiated pyrite cathode to achieve energy densities of ∼400 Wh/kg, far surpassing recent reports on SIBs and even the theoretical maximum for LIB technology (387 Wh/kg for LiCoO₂/graphite cells) while still relying on naturally abundant raw materials and cost-effective aqueous processing

Polysulfide Anchoring Mechanism Revealed by Atomic Layer Deposition of V₂O₅ and Sulfur-Filled Carbon Nanotubes for Lithium–Sulfur Batteries

Despite the promise of surface engineering to address the challenge of polysulfide shuttling in sulfur–carbon composite cathodes, melt infiltration techniques limit mechanistic studies correlating engineered surfaces and polysulfide anchoring. Here, we present a controlled experimental demonstration of polysulfide anchoring using vapor phase isothermal processing to fill the interior of carbon nanotubes (CNTs) after assembly into binder-free electrodes and atomic layer deposition (ALD) coating of polar V₂O₅ anchoring layers on the CNT surfaces. The ultrathin submonolayer V₂O₅ coating on the CNT exterior surface balances the adverse effect of polysulfide shuttling with the necessity for high sulfur utilization due to binding sites near the conductive CNT surface. The sulfur loaded into the CNT interior provides a spatially separated control volume enabling high sulfur loading with direct sulfur-CNT electrical contact for efficient sulfur conversion. By controlling ALD coating thickness, high initial discharge capacity of 1209 mAh/g_S at 0.1 C and exceptional cycling at 0.2 C with 87% capacity retention after 100 cycles and 73% at 450 cycles is achieved and correlated to an optimal V₂O₅ anchoring layer thickness. This provides experimental evidence that surface engineering approaches can be effective to overcome polysulfide shuttling by controlled design of molecular-scale building blocks for efficient binder free lithium sulfur battery cathodes

A Sugar-Derived Room-Temperature Sodium Sulfur Battery with Long Term Cycling Stability

We demonstrate a room-temperature sodium sulfur battery based on a confining microporous carbon template derived from sucrose that delivers a reversible capacity over 700 mAh/g_S at 0.1C rates, maintaining 370 mAh/g_S at 10 times higher rates of 1C. Cycling at 1C rates reveals retention of over 300 mAh/g_S capacity across 1500 cycles with Coulombic efficiency >98% due to microporous sulfur confinement and stability of the sodium metal anode in a glyme-based electrolyte. We show sucrose to be an ideal platform to develop microporous carbon capable of mitigating electrode–electrolyte reactivity and loss of soluble intermediate discharge products. In a manner parallel to the low-cost materials of the traditional sodium beta battery, our work demonstrates the combination of table sugar, sulfur, and sodium, all of which are cheap and earth abundant, for a high-performance stable room-temperature sodium sulfur battery

Electrically Conductive Hierarchical Carbon Nanotube Networks with Tunable Mechanical Response

Small diameter carbon nanotube (CNTs) are synthesized directly from a parent CNT forest using a floating catalyst chemical vapor deposition (CVD) method. To support a new CNT generation from an existing forest, an alumina coating was applied to the CNT forest using atomic layer deposition (ALD). The new generation of small diameter CNTs (8 nm average) surround the first generation, filling the interstitial regions. The hierarchical forests exhibit a 5–10-fold increase in stiffness, and the two generations are electrically addressable in spite of the interfacial alumina layer between them. This work enables the design of complex CNT architectures with hierarchical features that bring tailored properties such as high specific surface area and robust mechanical properties that can benefit a range of applications

From the Junkyard to the Power Grid: Ambient Processing of Scrap Metals into Nanostructured Electrodes for Ultrafast Rechargeable Batteries

Here we present the first full cell battery device that is developed entirely from scrap metals of brass and steeltwo of the most commonly used and discarded metals. A room-temperature chemical process is developed to convert brass and steel into functional electrodes for rechargeable energy storage that transforms these multicomponent alloys into redox-active iron oxide and copper oxide materials. The resulting steel–brass battery exhibits cell voltages up to 1.8 V, energy density up to 20 Wh/kg, power density up to 20 kW/kg, and stable cycling over 5000 cycles in alkaline electrolytes. Further, we show the versatility of this technique to enable processing of steel and brass materials of different shapes, sizes, and purity, such as screws and shavings, to produce functional battery components. The simplicity of this approach, building from chemicals commonly available in a household, enables a simple pathway to the local recovery, processing, and assembly of storage systems based on materials that would otherwise be discarded

Noncovalent Pi–Pi Stacking at the Carbon–Electrolyte Interface: Controlling the Voltage Window of Electrochemical Supercapacitors

A key parameter in the operation of an electrochemical double-layer capacitor is the voltage window, which dictates the device energy density and power density. Here we demonstrate experimental evidence that π–π stacking at a carbon–ionic liquid interface can modify the operation voltage of a supercapacitor device by up to 30%, and this can be recovered by steric hindrance at the electrode–electrolyte interface introduced by poly­(ethylene oxide) polymer electrolyte additives. This observation is supported by Raman spectroscopy, electrochemical impedance spectroscopy, and differential scanning calorimetry that each independently elucidates the signature of π–π stacking between imidazole groups in the ionic liquid and the carbon surface and the role this plays to lower the energy barrier for charge transfer at the electrode–electrolyte interface. This effect is further observed universally across two separate ionic liquid electrolyte systems and is validated by control experiments showing an invariant electrochemical window in the absence of a carbon–ionic liquid electrode–electrolyte interface. As interfacial or noncovalent interactions are usually neglected in the mechanistic picture of double-layer capacitors, this work highlights the importance of understanding chemical properties at supercapacitor interfaces to engineer voltage and energy capability

Differences in the Interfacial Mechanical Properties of Thiophosphate and Argyrodite Solid Electrolytes and Their Composites

Interfacial mechanics are a significant contributor to the performance and degradation of solid-state batteries. Spatially resolved measurements of interfacial properties are extremely important to effectively model and understand the electrochemical behavior. Herein, we report the interfacial properties of thiophosphate (Li3PS4)- and argyrodite (Li6PS5Cl)-type solid electrolytes. Using atomic force microscopy, we showcase the differences in the surface morphology as well as adhesion of these materials. We also investigate solvent-less processing of hybrid electrolytes using UV-assisted curing. Physical, chemical, and structural characterizations of the materials highlight the differences in the surface morphology, chemical makeup, and distribution of the inorganic phases between the argyrodite and thiophosphate solid electrolytes

Tailoring of the Anti-Perovskite Solid Electrolytes at the Grain-Scale

The development of thin, dense, defect-free solid electrolyte films is key for achieving practical and commercially viable solid-state batteries. Herein, we showcase a facile processing pathway for antiperovskite (Li2OHCl) solid electrolyte materials that can yield films/pellets with very high densities (∼100%) and higher conductivities compared with conventional uniaxially pressed pellets. We have also achieved close to 50% improvement in the critical current density of the material and an improved lithiophilicity due to the surface nitrogen enrichment of the processed pellets. Distribution of relaxation time analysis supports the contributions from “faster” transport mechanisms for the antiperovskite films/pellets developed using the new protocol. Overall, the results highlight the feasibility of our new processing pathway for engineering antiperovskite solid electrolytes at the grain scale as a highly desirable approach for practical all-solid-state batteries

The Role of Isostatic Pressing in Large-Scale Production of Solid-State Batteries

Scalable processing of solid-state battery (SSB) components and their integration is a key bottleneck toward the practical deployment of these systems. In the case of a complex system like a SSB, it becomes increasingly vital to envision, develop, and streamline production systems that can handle different materials, form factors, and chemistries as well as processing conditions. Herein, we highlight isostatic pressing (ISP) as a versatile processing platform for large-scale production of the currently most promising solid electrolyte materials. We briefly summarize the development of ISP techniques as well as the processing methods and windows accessible. Subsequently, we discuss recent reports on SSBs that leverage ISP techniques and their impact on the electrochemical performance of the systems. Finally, we also provide a techno-economic analysis for implementing ISP at scale along with some key perspectives, challenges, and future directions for large-scale production of SSB components and integration