The development of advanced materials and technologies to efficiently convert and store energy directly into electricity is of urgent importance due to increasing energy demands of an ever growing world population and decreasing energy reserves. However tremendous scientific challenges remain before successful implementation of any number of competing energy technologies such as solar cells, fuel cells, and batteries. The materials, interfaces and device architectures currently being explored are very challenging to interrogate by ensemble-averaging, bulk experimental methods since they do not exhibit long-range order or homogeneity, contain unique nano-morphological features and possess non-uniform chemical compositions and defect chemistry. This presentation will summarize a few materials design strategies for optimizing the performance of redox-active materials for use in electrochemical energy storage applications and highlight the development of high resolution experimental and theoretical tools for studying charge transfer processes at electrode interfaces. Information obtained from these studies provides fundamental understanding of electron and ion transfer processes and degradation mechanisms for materials utilized for electrochemical energy storage.

Structures, Devices, and Architectures for Nanoscale Solutions in Electrical Energy Storage
G.W. Rubloff
Nano science and technology promise enhancement to batteries and capacitors through higher power at given energy, accompanied by new possibilities for better capacity retention and safety. Among the challenges to realize this promise are (1) the design of higher performance electrode and electrolyte materials and (2) the rational design of structures in which these materials are arranged. We have focused on the latter, seeking to understand how the structure of components and the architecture in which they are arranged determine the multifunctionality required for electrical energy storage: ion transport and storage, electron transport, and structural stability during charge/discharge cycling.
Precision multistep synthesis has enabled the creation of heterogeneous nanostructures, involving multiple materials to confer the needed multifunctionality and to understand how design influences electrochemical behavior at the nanoscale and storage performance of nanostructures. This is illustrated by several such structures which address fundamental phenomena important at the nanoscale and the mesoscale, including: (1) Si nanowire and nanotube structures with integrated electron transport components that achieve robust Li cycling despite large volume changes; (2) nanopore battery configurations to assess fundamental limits on ion transport in highly confined environments; (3) solid state electrolyte and battery configurations for scaling safe materials to the nanoscale; and (4) 3D nanostructure forests, both regular and pseudo-random, to analyze mesoscale architectures and new scientific challenges emerging at the mesoscale. These experimental advances have been accompanied by significant modeling and simulation insights, from DFT to continuum levels, and at the same time they pose formidable, important challenges for theory, particularly at the mesoscale.
This work has been supported by Nanostructures for Electrical Energy Storage (NEES), an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Award Number DESC0001160.

The primary goal of the FIRST Center is to develop fundamental understanding and validated, predictive models of the unique nanoscale environment at fluid-solid interfaces that enable transformative advances in electrical energy storage and catalysis for energy. A signficant portion of our research has focussed on capacitive energy storage by ion attraction to charged interfaces, often termed electrical double layer capacitance. This type of electrical energy storage, which does not involve phase changes, redox reactions or ion intercalation into crystal lattices, frequently results in very long cycle lives and very hgh power densities, but lower energy densities than can be achieved by converting electrical to chemical energy in a battery. We have extensively explored the role of pore size versus ion size, nanoscale surface curvature and pore geometries in maximizing both power and energy density of capacitive and pseudocapacitive electrical energy storage, particularly involving room temperature ionic liquid electroltyes and nanotextured carbon electrode materials.

Energy storage represents an opportunity and a challenge for basic research to cross the technological boundaries in bringing energy independence to the U.S. Since its inception in 2009, the overriding mission of the Center for Electrical Energy Storage (CEES) has been to advance the fundamental understanding of electrochemical phenomena and the design of new materials architectures, using lithium-ion battery chemistries as a guide, for the discovery of a new generation of electrical energy storage systems.
This presentation will discuss the journey of CEES over the past 5 years. Highlights will include 1) approaches to design new anode and cathode materials and architectures, 2) the development of characterization techniques to monitor electrochemical processes at the electrode/electrolyte interface, 3) the use of autonomous chemistries to enable self-repair and shutdown reactions, and 4) theoretical approaches to complement experimental observations and discoveries.
Acknowledgments
This work was supported by the Center for Electrical Energy Storage, an Energy Frontier Research Center funded by the Office of Science, Office of Basic Energy Sciences of the U.S. Department of Energy.

This presentation will deal with the development of operando methods for the study and characterization of battery materials. The presentation will begin with a brief overview of the methods employed. Particular emphasis will be placed on the use of X-ray diffraction (XRD) and X-ray absorption spectroscopy (XAS), differential electrochemical mass spectrometry (DEMS) and transmission electron microscopy (TEM) under active potential control. The utility of these methods will be illustrated by selected examples including conversion reactions of Mn3O4 as anode material for lithium ion batteries (LIBs), spectroscopic studies of Li/S batteries and the use of DEMS to characterize electrolyte systems for LIBs. The use of operando TEM will be illustrated by studies of lithiation/de-lithiation dynamics of LiFePO4 via energy-filtered TEM. The presentation will conclude with an assessment of future directions.

The Northeastern Center for Chemical Energy Storage (NECCES) has leaded a synergistic effort in the past five years on basic research in the design of the next generation of lithium-ion batteries. The Center has enabled both the development of new chemistries and the fundamental understanding of the physical and chemical processes that occur in intercalation materials such as LiFePO4 and conversion materials such as FeF3/FeF2. The NECCES team has identified the key atomic-scale processes that govern electrode function in rechargeable batteries, over a wide range of time and length scales, via the development and use of novel characterization and theoretical tools, including in situ X-ray scattering, in situ TEM observation, in situ NMR spectroscopy and new computation/simulation tools. The information and knowledge gained are critical to identify and design new battery systems with improved electrochemical properties.

The Joint Center for Energy Storage Research combines discovery science, battery design, research prototyping and manufacturing collaboration in a single highly interactive organization to pursue transformational next generation energy storage beyond lithium ion batteries. JCESR will leave three legacies:
- a library of fundamental knowledge of the materials and phenomena of energy storage at the atomic and molecular level
-two prototypes, one for the grid and one for transportation, that, when scaled to manufacturing will be able to deliver five times the energy density at one-fifth the cost
-a new paradigm for battery R&D that accelerates the pace of discovery and innovation and significantly shortens the time from discovery to commercialization.
An introduction to JCESR&’s vision, mission and legacies will be followed by research highlights illustrating its advances in fundamental science and the promising pathways to transformational battery designs and prototypes.
This work was supported as part of the Joint Center for Energy Storage Research, an Energy Innovation Hub funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences
Contact information
George Crabtree
Director, Joint Center for Energy Storage Research (JCESR)
Argonne National Laboratory
9700 S. Cass Ave
Argonne, IL 60439
630 252 5509
crabtree@anl.gov
Departments of Physics, Electrical and Mechanical Engineering
University of Illinois at Chicago
845 W. Taylor St. M/C 273
Chicago, IL 60607
Tel 630 252 5509
crabtree@uic.edu
Executive Assistant
Bernadette (Nada) Petrovic
Joint Center for Energy Storage Research (JCESR)
Argonne National Laboratory
9700 S. Cass Ave
Argonne, IL 60439
(630) 252-1420
bpetrovic@anl.gov

Intercalation electrodes provide the highest energy density battery systems. Hence, understanding diffusion of ions other than Li in such electrode materials is important to assess the feasibility of “Beyond Li” technologies. Both Na and Mg are being considered as alternatives to lithium. In this presentation we will compare the diffusion mechanisms for Li, Na and Mg in typical intercalation materials. Layered Na-oxides have recently been shown to be able to achieve rates > 30C, and in many layered oxides Na diffusion seems faster than Li diffusion. Mg being a divalent ion shows much slower diffusion in many intercalation hosts. Results for the migration barrier of Mg diffusion in different hosts will be shown.

The extraction, exchange, and separation of ions in solution have been studied extensively because of applications in seawater desalination, elemental purification, and wastewater treatment. Reversible electrochemical insertion of ions into materials would present a valuable alternative to existing methods of ion exchange because of the ease of cycling and reuse. Reversible insertion of monovalent ions has been thoroughly explored because of its application in intercalation battery electrodes, including electrodes for nickel-metal hydride and lithium-ion batteries. However, the stable and reversible insertion of divalent or trivalent ions into materials remains an unsolved problem.
Copper hexacyanoferrate (CuHCF), a Prussian Blue analogue, possesses a unique open framework structure that allows for the reversible insertion of a wide variety of multivalent cations, including many alkaline earth, rare earth, and transition metal cations. The material demonstrates unprecedented kinetics, reversibility, and cycle life for multivalent ion insertion. However, little is known about the processes by which multivalent ions can readily insert into CuHCF. Ongoing synchrotron X-ray and neutron diffraction experiments have begun to provide insight on the ion insertion mechanism in the material and on the complex interplay between vacancies, water molecules, and insertion ions in the structure.

Cubic garnet of nominal composition Li7La3Zr2O12 (LLZO) is of interest as a possible electrolyte in batteries composed of molten Li as an anode and sulfur or an insoluble metal halide as a cathode operating in the temperature range 300-350C. As a consequence the chemical stability of dense (>98% relative density) cubic LLZO stabilized by different dopants in molten lithium and sulfur in the temperature range 300-350C was characterized by x-ray diffraction, electron microscopy, x-ray photoemission spectroscopy and electron paramagnetic resonance. The results revealed LLZO had undergone chemical coloration and exhibited intergranular cracking after immersion in molten Li. These results will discussed and compared to other Li and Na-ion conductors tested in a similar temperature range.