Search

Next generation solid-state batteries (SSB) will need to leverage high voltage cathodes, as well as metallic anodes to achieve the realistic performance targets necessary to replace liquid electrolyte-based batteries in cutting-edge applications including electric vehicles. However, limitations arising from mass and charge transports, kinetics and chemo-mechanical degradation at the electrode | electrolyte interface limit the performance of present day SSBs. Optimizing composite cathode architecture, which is an integral part of solid-state batteries, is vital to realize the high-energy density and high-performance goals for next-generation solid-state batteries. Cathode architecture needs to be optimized for high loadings of active material, well-percolated ion and electron transport pathways and increased resilience against electrochemical stresses. This paper provides a first report of framework for geometric modeling of composite cathode architectures and evaluates the impact of cathode architecture on cell-level energy density using hierarchical models. Packing around primary and secondary active material particles are simulated for a range of active material particle size and solid electrolyte size distributions in the composite cathode. Impact of packing architecture on processing parameters of a given cathode composition and thickness, as well as on achievable energy density is evaluated for a range of commonly used solid electrolyte and cathode materials. Overall, the proposed framework offers a facile exploratory methodology for establishing initial metrics for scalable processing of practical and competent SSBs.

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 (Li

Today, the burgeoning drive towards global urbanization with over half the earth’s population living in cities, has created major challenges with regards to intracity and intercity transit and mobility. This problem is compounded due to the fact that almost always urbanization and increase in standard of living drives individual automobile ownerships. Over 95% of automobiles are presently powered by some form of fossil fuel and as an unintended consequence, urban centers have also been centers for peak greenhouse gas emissions, a major contributor to global climate change. A revolutionary solution to this conundrum is flight capable electric automobiles or electric aerial vehicles that can tackle both urban mobility and climate change challenges. For such advanced electric platforms, energy storage and delivery component is the vital component towards achieving takeoff, flight, cruise, and landing. The requirements and duty cycle demands on the energy storage system is drastically different when compared to the performance metrics required for terrestrial electric vehicles. As the widely deployed lithium ion-based battery systems are often the primary go-to energy storage choice in electric vehicle related applications, it is imperative that performance metrics and specifications for such batteries towards areal electric vehicles need to be established. In this nascent field, there exists ample opportunities for battery material innovations, understanding degradation mechanism, battery design, development and deployment of battery control and management systems. Thus, this chapter comprehensively discusses battery requirements and identifies battery material chemistries suitable for handling aerial electric automobile duty cycles. The chapter also discusses the battery cell-level metrics pertaining to electrochemical, chemical, mechanical, and structural parameters. Furthermore, specific models for battery degradation, state of health (SOH), capacity and models for full cell performance and degradation are also discussed here. Finally, the chapter also discusses battery safety and future directions of batteries that would power these next generation urban electric aircrafts.

Artificial barriers, usually with either electrochemically active or inactive coating materials, are deployed on cathode material surfaces to mitigate detrimental side reactions by suppressing direct contact of cathode and electrolyte called surface coatings. These surface coatings are commonly known to increase the wettability of liquid electrolyte and reduce the interfacial charge transfer resistance. An important caveat is the selection of appropriate coating material with appropriate thickness for achieving enhanced electrochemical performance. As modern battery materials are increasingly developed with some type of surface coating, a careful and thorough examination of their role in mitigating the cycle life issues of cathode materials is paramount. This comprehensive review article extensively covers the selection criteria of coating materials based on their chemical and physical properties and electrochemical functionalities. Additionally, the article discusses the concept of critical coating thickness and methods of achieving homogeneous coating architectures that deliver desired performance benefits. Furthermore, this comprehensive article summarizes the recent advancements, effectiveness, necessity of cathode surface coatings and identifies the key aspect of structure-property correlation between coating type/thickness and lithium-ion diffusion through coating layers as the linchpin that validates surface coating approaches especially for high capacity nickel-rich cathodes.

Here we report dual ion conduction capability of Na-based NASICON type super ion conductor materials using Na1+xMnx/2Zr2–x/2(PO4)3 (NMZP) as a candidate system. This method enables the use of Na-ba...

The emergence and dominance of lithium-ion batteries in expanding markets such as consumer electronics, electric vehicles, and renewable energy storage are driving enormous interests and investments in the battery sector. The explosively growing demand is generating a huge number of spent lithium-ion batteries, thereby urging the development of cost-effective and environmentally sustainable recycling technologies to manage end-of-life batteries. Currently, the recycling of end-of-life batteries is still in its infancy, with many fundamental and technological hurdles to overcome. Here, the authors provide an overview of the current state of battery recycling by outlining and evaluating the incentives, key issues, and recycling strategies. The authors highlight a direct recycling strategy through discussion of its benefits, processes, and challenges. Perspectives on the future energy and environmental science of this important field is also discussed with respect to a new concept introduced as the Battery Identity Global Passport (BIGP).

Sodium-ion batteries (NaIBs) are increasingly being envisioned for grid-scale energy-storage systems because of cost advantages. However, implementation of this vision has been challenged by the low-energy densities delivered by most NaIB cathodes. Toward addressing this challenge, the authors report the synthesis and characterization of a new iron-doped Na3Fe0.3V1.7O(PO4)2F2 cathode using a novel facile hydrothermal route. The synthesized material was characterized using scanning electron microscopy, X-ray diffraction, and Mossbauer spectroscopy techniques. The obtained discharge capacity in the half-cell configuration lies from 119 to 125 to 130 mA h/g at C/10 while tested using three different electrolyte formulations, dimethyl carbonate-ethylene carbonate (EC)-propylene carbonate (PC), diethyl carbonate-EC, and EC-PC, respectively. The synthesized cathodes were also evaluated in full-cell configurations, which delivered an initial discharge capacity of 80 mA h/g with NaTi2(PO4)3MWCNT as the anode. Ionic diffusivity and interfacial charge transfer kinetics were also evaluated as a function of temperature and sodium concentration, which revealed that electrochemical rate performances in this material were limited by charge-transfer kinetics. To understand the heat generation mechanism of the Na/Na3Fe0.3V1.7O(PO4)2F2 half-cell during charge and discharge processes, an electrochemical isothermal calorimetry measurement was carried out at different current rates for two different temperatures (25 and 45 °C). The results showed that the amount of heat generated was strongly affected by the operating charge/discharge state, C-rate, and temperature. Overall, this work provides a new synthesis route for the development of iron-doped Na3Fe0.3V1.7O(PO4)2F2-based high-performance sodium cathode materials aimed at providing a viable pathway for the development and deployment of large-scale energy-storage based on sodium battery systems.

As lithium-ion battery (LIB) active material and cell manufacturing costs continue to drop with wider adoption of electric vehicles, electrode and cell processing costs remain too high in terms of reaching the ultimate U.S. Department of Energy (DOE) cell cost target of $80/kWh. This paper primarily covers major materials chemistry advancements made over the last 10 ​years ​at Oak Ridge National Laboratory (ORNL) in the space of advanced manufacturing science for LIBs with the aim of simultaneously meeting the ultimate cost target, 500 ​Wh/kg gravimetric energy density, 10-15-min fast charge times, and 1000 deep discharge cycles. Aqueous electrode processing with a variety of active anode and cathode materials is now a standard procedure at the DOE Battery Manufacturing R&D Facility at ORNL (BMF), including the latest processes developed for Ni-rich cathodes. New results on cobalt-free LiNi0.8Fe0.1Al0.1O2 (NFA 811) are also included and discussed in an electrode processing advantage context. In addition, colloidal processing advancements have been made for Si/C composite anodes for achieving >600 ​mA ​h/g capacities. Optimization of electrode coating parameters and drying protocols have been completed, which has elucidated how key processing variables need to be changed when parameters such as slurry solids loading, solvent type, and wet electrode thickness are changed. ORNL has also increased the line speeds at which thick cathodes can be processed using ultra-fast electron beam (EB) curing and substantially decreased formation cycling times to

An engaging area of research in sodium-ion batteries (SIBs) has been focusing on discovery, design, and synthesis of high-capacity cathode materials in order to boost energy density to levels close enough to that of state-of-the-art lithium-ion batteries. Of particular interest, P2-type layered oxide, Na2/3Fe1/2Mn1/2O2, has been researched as a potential cathode in SIBs based on its high theoretical capacity of 260 mA h/g and use of noncritical materials. However, the reported synthesis methods are not only complex and energy-demanding but also often yield inhomogeneous and impure materials with capacities less than 200 mA h/g under impractical test conditions. Here, we report a novel synthesis route using low-temperature eutectic reaction to produce highly homogeneous, crystalline, and impurity-free P2-NaxFe1/2Mn1/2O2 with enhanced Na-ion diffusivity and kinetics. The overall electrochemical performances of the Na-ion cells have been improved by pairing the P2-cathode with presodiated hard carbon anodes, leading to reversible capacities in the range of 180 mA h/g. This new approach is a contribution toward the simplification of synthesis and scalability of sodium-based cathodes with high crystallinity and fine-tuned morphology and the realization of a sodium-ion battery system with lower cost and improved electrochemical performance.

Solid-state battery (SSB) is the new avenue for achieving safe and high energy density energy storage in both conventional but also niche applications. Such batteries employ a solid electrolyte unlike the modern-day liquid electrolyte-based lithium-ion batteries and thus facilitate the use of high-capacity lithium metal anodes thereby achieving high energy densities. Despite this promise, practical realization and commercial adoption of solid-state batteries remain a challenge due to the underlying material and cell level issues that needs to be overcome. This chapter thus covers the specific challenges, design principles and performance improvement strategies pertaining to the cathode, solid electrolyte and anode used in solid state batteries. Perspectives and outlook on specific applications that can benefit from the successful implementation of solid-state battery systems are also discussed. Overall, this chapter highlights the potential of solid-state batteries for successful commercial deployment in next generation energy storage systems.

The major challenges for the development of all solid-state batteries (ASSBs), that would be cheaper and can be charged and discharged faster, are stable solid electrolytes and robust interfacial design. We report the dual ion conduction capability of Na-based NASICON type super ion conductor materials using Na1+xMnx/2Zr2-x/2(PO4)3 (NMZP) as a candidate system [1]. This method enables the use of Na-based NASICON material family in both Na as well as Li all solid-state batteries (Figure 1a). The ionic conductivity NZMPs increased as the x value increased and x = 2 showed the highest room temperature conductivities. Crystallographic analysis using neutron diffraction revealed that conductivities observed in these materials are related to the variations in the Na-O bond length and the concentration of mobile sodium content. Using Galvano static plating and stripping tests, we show that these NMZPs boast good cycling stability against both Na and Li metals which also reveals dual ion conduction. Mechanistic investigations through postmortem SEM/EDS and XPS characterizations of the alkali metal and the cycled NMZPs confirm that the Na-Li ion exchange occurs readily in these materials when electrochemically cycled. ASSBs have several interfaces and the interface properties vary depending on the contact condition, energy states, type defects, and chemical/electrochemical stability. ASSB life and performance rely largely on these interfaces since dendrite formation, Li-depleted space-charge layer generation, and spatial variation in interfacial adhesion originate at the interfaces, which leads to battery failure. Stabilizing Li | SE interface is crucial for the development of high-energy-density solid-state batteries. Current approaches in Li metal stabilization employ energy and cost-intensive protocols that have a detrimental impact on the techno-economic feasibility of the ASSBs. This presentation will focus on the facile, electrochemical protocol for improving the interfacial impedance and contact at the Li | Li6.25Al0.25La3Zr2O12 (LALZO) interface. Implementation of a fraction of second short duration high voltage pulse to a poorly formed interface leads to a sustained improvement in contact impedance and lower overpotentials for electrodeposition and electro-dissolution [2] (Figure 1b). This high pulse protocol does not induce the formation of dendrites on the symmetric cells. This electrochemical protocol has direct application in battery formation cycles as well as online management systems for ASSBs. Reference [1]. A. Parejiya, R. Essehli, R. Amin, J. Liu, N. Muralidharan, H. M. Meyer, III, D. L. Wood, III, and I. Belharouak, ACS Energy Letters 6 (2021) 429. [2]. A. Parejiya, R. Amin, M.B. Dixit, R. Essehli, C. Jafta, D.L. Wood, and I. Belharouak., ACS Energy Lett. 6 (2021) 3669. Figure 1

Solid-state batteries are pivotal technologies for next-generation energy storage needs. However, they are plagued with various challenges from materials and interfaces all the way out to integration into devices. Herein, we discuss several new pathways that our team has evaluated to drive the research towards practical solid-state batteries. Initially, we highlight SolidPAC, which is an interactive experimental toolkit developed at Oak Ridge National Laboratory to enable the design of a solid-state battery for user-specified application requirements. The toolkit is flexible enough to assist the battery community in quantifying the impact of materials chemistry and fractions, electrode thicknesses and loadings, and electron flows on cell energy density and cost. The toolkit allows users to assess and extrapolate the impact of battery design and choice of cell components on cell-level energy density of a solid-state battery. Subsequently, we will discuss some key experimental strategies that leverage cheap and scalable electrochemical approaches towards the integration and on-line management of solid-state batteries. Specifically, these approaches are aimed to alleviate high interfacial resistances typically observed in some SSB configurations as well as to mitigate the growth of filaments within the solid electrolyte.

Solid-state batteries are promising alternatives for high-energy and -power-density rechargeable battery applications. It is vital to design and engineer SSB cells that can compete and improve on the current Li-ion battery counterparts. However, limited approaches exist today to assess and extrapolate the impact of battery designs and choices of cell components on the cell-level energy density of a solid-state battery. Herein, we introduce the Solid-State Battery Performance Analyzer and Calculator (SolidPAC), an interactive experimental toolkit to enable the design of a solid-state battery for user-specified application requirements. The toolkit is flexible enough to assist the battery community in quantifying the impact of materials chemistry and fractions, electrode thicknesses and loadings, and electron flows on cell energy density and costs and in utilizing inverse engineering concepts to correlate the cell energy density output to materials and cell design inputs. In addition to this, we will discuss a geometric modeling of composite cathode architectures to assess its impact on cell-level energy densities. Impact of packing architecture on processing parameters of a given cathode composition and thickness, as well as on achievable energy density is evaluated for a range of commonly used solid electrolyte and cathode materials. Overall, the proposed framework offers a facile exploratory methodology for establishing initial metrics for scalable processing of practical and competent SSBs.

Thermal insulation materials are highly sought after for applications such as building envelopes, refrigerators, cryogenic fuel storage chambers, and water supply piping. However, current insulation materials either do not provide sufficient insulation or are costly. A new class of insulation materials, hollow silica particles, has attracted tremendous attention due to its potential to provide a very high degree of thermal insulation. However, current synthesis strategies provide hollow silica particles at very low yields and at high cost, thus, making the particles unsuitable for real-world applications. In the present work, a synthesis process that produces hollow silica particles at very high yields and at a lower cost is presented. The effect of an infrared heat absorber, carbon black, on the thermal conductivity of hollow silica particles is also investigated and it is inferred that a carbon black–hollow silica particle mixture can be a better insulating material than hollow silica particles alone.

In recent years, cobalt has become a critical constraint on the supply chain of the Li-ion battery industry. With the ever-increasing projections for electric vehicles, the dependency of current Li-ion batteries on the ever-fluctuating cobalt prices poses serious environmental and sustainability issues. To address these challenges, a new class of cobalt-free materials with general formula of LiNi

In the past decade, interest in hollow silica particles has grown tremendously because of their applications in diverse fields such as thermal insulation, drug delivery, battery cathodes, catalysis, and functional coatings. Herein, we demonstrate a strategy to synthesize hybrid hollow silica particles having shells made of either polymer-silica or carbon–silica. Hybrid shells were characterized using electron microscopy. The effect of hybrid shell type on particle properties such as thermal and moisture absorption was also investigated.

Here we demonstrate a composite material exhibiting dual multifunctional properties of a structural material and a redox-active battery. This incorporates three-dimensional aligned carbon nanotube interfaces that weave together a structural frame, redox-active battery materials, and a Kevlar-infiltrated solid electrolyte that facilitates ion transfer. Relative to the total measured composite material mass, we demonstrate energy density up to ∼1.4 Wh/kg, elastic modulus of 7 GPa, and tensile strength exceeding 0.27 GPa. Mechano-electrochemical analysis demonstrates stable battery operation under mechanical loading that validates multifunctional performance. These findings demonstrate how battery materials that are normally packaged under compression can be reorganized as elements in a structurally reinforced composite material.

Here we report a room-temperature sodium metal battery, where the sodium initially stored in a Na3V2(PO4)3 cathode is plated, upon charging, onto an aluminum current collector coated with a thin nucleation layer. To maximize the battery performance, conventional sodium-ion anode materials, including non-graphitized carbons and sodium-alloying metals, were evaluated as nucleation layers to facilitate stable electroplating of sodium metal. Among several materials studied, carbon black and bismuth showed the highest sodium plating–stripping coulombic efficiencies in half-cell testing, averaging 99.9% and 99.85%, respectively, over 50 cycles at 0.5 mA cm−2. Building on these findings, anode-free cells with Na3V2(PO4)3 cathodes were assembled in a discharged state, demonstrating energy densities up to 318 W h kg−1 at 0.25 mA cm−2 (∼C/6), a first-cycle coulombic efficiency up to 92%, a stable discharge voltage at 3.35 V, an average round-trip energy efficiency of 98%, and a capacity retention of 82.5% after 100 cycles at 0.5 mA cm−2 (∼C/3). With its unique performance highlighted in this work, the anode-free sodium battery emerges as a low-cost, high-performance option for stationary electric storage.

Scaffold structures of electrospun aluminum–substituted lithium lanthanum zirconate Li7La3Zr2O12 (Al-LLZO) were synthesized and used as an additive in a LiNi0.6Mn0.2Co0.2O2 composite cathode. The scaffolds were crystalized in the cubic phase after calcination at 700 °C. The Al-LLZO scaffold morphology was dependent on the precursor formulation (aqueous and dimethylformamide. The aqueous precursors resulted in scaffolds of densely coalesced ligaments, whereas the dimethylformamide precursors resulted in high–aspect ratio nanofiber scaffolds. The long-term cycling stability and rate performance of the cells were found to depend on the Al-LLZO scaffold morphology. The uniformly dispersed Al-LLZO fibers resulted in a more stable cathode electrolyte interface formation through the reduced decomposition of the LiPF6 salt during cycling, resulting in a better high-rate and long-term cycling performance.

Advances in piezoelectric or triboelectric materials have enabled high-frequency platforms for mechanical energy harvesting (>10 Hz); however, virtually all human motions occur below 5 Hz and therefore limits application of these harvesting platforms to human motions. Here we demonstrate a device configuration based on sodiated black phosphorus nanosheets, or phosphorene, where mechanoelectrochemical stress–voltage coupling in this material is capable of efficient energy harvesting at frequencies as low as 0.01 Hz. The harvester is tested using both bending and pressing mechanical impulses with peak power delivery of ∼42 nW/cm2 and total harvested energy of 0.203 μJ/cm2 in the bending mode and ∼9 nW/cm2 and 0.792 μJ/cm2 in the pressing mode. Our work broadly demonstrates how 2D materials can be effectively leveraged as building blocks in strategies for efficient electrochemical strain energy harvesting.

Increasing amounts of nondegradable waste and rising levels of atmospheric carbon dioxide (CO2) similarly threaten a sustainable future, leaving routes to address these issues at the forefront of ongoing research efforts. Here, we demonstrate a route where electrochemical processing of scrap metals extracts catalytic species to the surface that actively convert CO2 scavenged from the atmosphere to form multiwalled carbon nanotubes (MWCNTs). Our findings demonstrate two distinct pathways for this technique that is generalizable to a broad range of scrap metals. First is the case where the catalytic elements are the primary constituents of the material (e.g., Fe in stainless steel) and the reaction with CO2 consumes the material. Second is the case where the catalytic elements are impurities (e.g., Fe in brass) where reaction with CO2 leads to impurity consumption. Our results demonstrate facile growth of MWCNTs directly from irregular scraps, such as shavings and pipes. Overall, this study presents a route...

The interplay between mechanical strains and battery electrochemistry, or the tunable mechanochemistry of batteries, remains an emerging research area with limited experimental progress. In this report, we demonstrate how elastic strains applied to vanadium pentoxide (V2O5), a widely studied cathode material for Li-ion batteries, can modulate the kinetics and energetics of lithium-ion intercalation. We utilize atomic layer deposition to coat V2O5 materials onto the surface of a shapememory superelastic NiTi alloy, which allows electrochemical assessment at a fixed and measurable level of elastic strain imposed on the V2O5, with strain state assessed through Raman spectroscopy and X-ray diffraction. Our results indicate modulation of electrochemical intercalation potentials by ∼40 mV and an increase of the diffusion coefficient of lithium ions by up to 2.5-times with elastic prestrains of

Until now, research efforts focused on electrochemical conversion of carbon dioxide into stable carbon-based materials have been limited by poor understanding of catalytic effects occurring at surfaces. Here, we demonstrate the capability to simultaneously use atomic layer deposition (ALD), electrode composition control, and current density as a means to direct the formation of iron-based catalysts and grow highly crystalline multi-walled carbon nanotubes at high yields (99%) and with controlled average diameters of 27.5 nm from ambient carbon dioxide captured and dissolved in molten carbonate electrolytes. ALD of passive alumina coatings on a Ni anode prevents electrode corrosion processes and adverse deposition of Ni on the cathode that results in increased CNT diameters, lower CNT quality, and non-CNT products. On the cathode side where CNT growth occurs, our results elucidate the fine balance of iron catalyst accessibility from the cathode interior and the surface chemical properties in order to achieve high yield and high quality CNT growth. Our work provides an intersection between decades of research understanding on catalytic gas-phase growth of CNT materials and the ability to leverage these ideas to sustainably capture ambient carbon dioxide and produce functional CNT materials.

Here we demonstrate an isothermal technique that enables rapid vapor infiltration of sulfur into carbon templates to overcome scalability and performance bottlenecks associated with common melt infiltration techniques. Building on straightforward thermodynamic principles of capillary condensation, self-limited sulfur loadings up to 82 wt % can be achieved in as little as 10 min at temperatures between 155 and 175 °C. We demonstrate a broad range of device performance criteria using a carbon black–single-walled carbon nanotube binder-free cathode framework, including a side-by-side comparison to melt infiltrated electrodes with 74 wt % loading that shows improved capacity (1015 mAh/g vs 768 mAh/g), ∼92% capacity retention after 200 cycles at 0.5 C, and ∼98% Coulombic efficiency as a result of enhanced uniformity and conductivity. Further, we demonstrate this technique over a range of different electrodes (1) electrodes with high sulfur loading (82 wt %) with high initial discharge capacity of 1340 mAh/g, (...

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 discha...

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 ...

Here we report the first mechanistic study investigating the effect of carbon defects on the evolution of different sodium–red phosphorus (red P) alloy states for stable high capacity sodium ion battery anodes. Using tunable sp2/sp3 carbon composites containing controlled single-walled carbon nanotube (SWCNT) and single-walled carbon nanohorn (SWCNH) compositions, we identify potentials over which both stable and unstable alloying of red P occurs with sodium. Examination of the stable alloy region includes both NaP and Na5P4 formation that occurs between 0.40 and 0.15 V where alloying is mostly independent of the carbon composite matrix chemistry. However, an unstable region corresponding to Na3P formation below 0.15 V results in capacity degradation that directly correlates with the density of carbon defects. In the unstable region, defects are observed to initiate deep alloying and poor reversibility due to the formation of irreversible Na3P products that form over the carbon surface. Our results present a mechanistic roadmap to guide the design of red P–carbon composite anodes to approach high theoretical sodium ion capacity (2596 mA h g−1) while simultaneously addressing chemical interactions that compromise performance stability.

Here, we report a wet synthesis-based titanium doping strategy to improve the structural stability and electrochemical performances, such as cycling stability and rate capability, of P2-type Na0.67Fe0.5Mn0.5O2 layered oxide cathodes. Through Ti4+ doping aimed at replacing some of the Mn and Fe atoms in the crystal structure, effective mitigation of the Jahn Teller distortion caused by active Mn3+ before charging and Fe4+ after charging was achieved. X-ray diffraction (XRD), Raman spectroscopy, Electrochemical Impedance Spectroscopy (EIS) and Mossbauer spectroscopy were used to investigate the effects of the Ti4+ dopant before and after cycling. It was observed that Ti4+ doping increased the Na layer thickness, minimized the lattice volume strain, showed better structural stability, minimally decreased Fe migration to the Na layer, and lowered charge transfer resistance in these P2-type cathodes. Overall, our reported synthesis methodology and electrochemical characterizations highlight the feasibility of Ti doping in sodium layered oxide P2-type cathodes.

The battery manufacturing industry has a cobalt problem! Over the recent years, rapid fluctuations in cobalt prices have created a drastic supply chain constraint that threatens to derail the burgeoning projections for electric vehicles over the next few decades. To reduce the cost of modern batteries to ~80$/kWh (to sustain the growing electric vehicle demands), it has become paramount that the amount of cobalt, the most expensive present-day battery cathode raw material, should be reduced to less than 50 mg at the cell level. Moreover, it is also important that any alternative cathode material developed, should facilitate a seamless integration into existing global battery manufacturing infrastructures to avoid a complete overhaul. The search for viable alternatives that address these challenges simultaneously is a continuing quest in today's battery research and development sectors. In this context, our team through a paradigm shifting approach has developed a new class of layered lithium ion battery cathode material with '0' cobalt in its composition. This new class of battery cathodes, termed the NFA class, has the general formula, LiNixFeyAlzO2 (where, x + y + z = 1)[1,2]. These layered cobalt-free cathodes are analogous in crystal structure and material properties to mainstream cobalt containing cathodes such as NCMs and NCAs while delivering comparable and in some cases better electrochemical performance. Here, I will present our efforts in the systematic development of these novel cathodes starting from compositional landscape investigations and advanced characterizations employing NFA material synthesized using the lab-scale sol-gel process. Through our approach, in-situ high temperature X-Ray and Neutron diffraction techniques were used to investigate the calcination and phase formation behavior while operando investigations using X-Ray diffraction and Mössbauer spectroscopy were employed to obtain a mechanistic understanding of the charge/discharge process of this new cobalt-free cathode material. Following these, the most promising compositional variants were upscaled using the co-precipitation process in continuous stirred tank reactors for obtaining kg levels of cathode material. Systematic optimization of reaction process variables ensured good particle morphologies, homogeneities and composition control. Electrochemical performance assessments performed in both half-cell and full-cell configurations tested in different voltage windows with upper cut-off voltages ranging from 4.1V to 4.5V demonstrated that the optimized NFA compositional variants deliver high capacities >200 mAh/g at 0.1C with good capacity retention >80% when cycled at C/3. Full pouch-cells (>1.5Ah) were then assembled using NFA electrodes fabricated using the slot-die coating technique with the upscaled cathode material demonstrating reasonable capacity retentions[3]. While the work presented here is still in an early stage of research, the immense potential that these NFA class of cathodes could have as viable candidates towards development of next generation cost effective lithium ion batteries is highlighted here. Overall, our research efforts in the development of this new class of cobalt-free cathodes aims to mitigate the battery industry's cobalt problem paving a promising pathway towards the wide adoption of electric vehicles in the coming decades. References: [1] Muralidharan, Nitin, et al. "LiNixFeyAlzO2, a new cobalt-free layered cathode material for advanced Li-ion batteries." Journal of Power Sources 471 (2020): 228389. [2] Muralidharan, Nitin, et al. "Lithium Iron Aluminum Nickelate, LiNixFeyAlzO2—New Sustainable Cathodes for Next‐Generation Cobalt‐Free Li‐Ion Batteries." Advanced Materials 32.34 (2020): 2002960. [3] Wood III, David L., et al. "Perspectives on the relationship between materials chemistry and roll-to-roll electrode manufacturing for high-energy lithium-ion batteries." Energy Storage Materials (2020).

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 commonly available chemicals enables a simple pathway to the local recovery, processing, and assembly of storage systems based on materials that would otherwise be discarded.

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.

Despite widespread focus on porous carbons for lithium-sulfur battery cathode materials, electrode design to preserve mass-specific performance and sustained extended cycling stability remains a challenge. Here, we demonstrate electrochemically etched porous silicon as a sacrificial template to produce a new class of functional mesoporous carbons optimized for dual chemical and physical confinement of soluble polysulfides in lithium-sulfur battery cathodes. Melt infiltration loading of sulfur at 60 wt% enables initial discharge capacity of 1350 mAh/gsulfur at rates of 0.1 C - approaching theoretical capacity of 1675 mAh/gsulfur. Cycling performance measured at 0.2 C indicates 81% capacity retention measured over 100 cycles with 830 mAh/gsulfur capacity. Unlike other carbons, this template combines structural properties necessary for sulfur containment and polysulfide confinement to achieve high specific capacity, but also boasts surface-bound oxygen-containing functional groups that are able to chemically anchor the soluble Li2Sn species on the interior of the mesoporous carbon to sustain cycling performance. In turn, this elucidates a scalable and competitive material framework that is capable, without the addition of additional membranes or inactive anchoring materials, of providing the simultaneous anchoring and confinement effects necessary to overcome performance limitations in lithium sulfur batteries.

We report the first demonstration of potassium ion cointercalation into graphitic carbon electrodes including both natural graphite and multi-layered graphene in both diglyme and monoglyme based electrolytes. Contrary to conventional desolvation-based intercalation of potassium, we demonstrate excellent capacity retention of ∼80% at rates up to 10 A g−1 (30 second charge), with 95% capacity retention over 1000 cycles, and up to 100 mA h g−1 capacity. Raman and X-ray diffraction following 1000 cycles demonstrates no signature of defects, damage, or change to graphitic crystallinity compared to uncycled pristine materials that is attributed to weak ion–lattice interactions due to the solvated guest K ions. In situ Raman spectroscopy highlights the sequential formation of a stage 4, 3, 2, and 1 graphite intercalation compound (GIC) that occurs without the signature of dilute staging. In a charged stage 1 compound, we observe lattice expansion from 0.335 nm to 1.16 nm and measure the work function to be ∼3.4 eV. Overall, this system overcomes rate and durability bottlenecks that limit current K-ion battery electrodes, and gives promise to cointercalation for durable, fast, and low-cost storage systems.