Structural Complexities in Sodium Ion Conductive Antiperovskite Revealed by Cryogenic Transmission Electron Microscopy.

We use low-dose cryogenic transmission electron microscopy (cryo-TEM) to investigate the atomic-scale structure of antiperovskite NaNHBH crystals by preserving the room-temperature cubic phase and carefully monitoring the electron dose. Via quantitative analysis of electron beam damage using selected area electron diffraction, we find cryogenic imaging provides 6-fold improvement in beam stability for this solid electrolyte. Cryo-TEM images obtained from flat crystals revealed the presence of a new, long-range-ordered supercell with a cubic phase.

Ultrahigh Areal Capacity Li Electrodeposition at Metal-Solid Electrolyte Interfaces under Minimal Stack Pressures Enabled by Interfacial Na-K Liquids.

The need for higher energy density rechargeable batteries has generated interest in metallic electrodes paired with solid electrolytes. However, impedance growth at the Li metal-solid electrolyte interface due to void formation during cycling at practical current densities and areal capacities, e.g.

Bayesian-Optimization-Assisted Laser Reduction of Poly(acrylonitrile) for Electrochemical Applications.

Laser reduction of polymers has recently been explored to rapidly and inexpensively synthesize high-quality graphitic and carbonaceous materials. However, in past work, laser-induced graphene has been restricted to semiaromatic polymers and graphene oxide; in particular, poly(acrylonitrile) (PAN) is claimed to be a polymer that cannot be laser-reduced successfully to form electrochemically active material. In this work, three strategies to surmount this barrier are employed: (1) thermal stabilization of PAN to increase its sp content for improved laser processability, (2) prelaser treatment microstructuring to reduce the effects of thermal stresses, and (3) Bayesian optimization to search the parameter space of laser processing to improve performance and discover morphologies.

Synthesis and Characterization of Dense Carbon Films as Model Surfaces to Estimate Electron Transfer Kinetics on Redox Flow Battery Electrodes.

Redox flow batteries (RFBs) are a promising electrochemical technology for the efficient and reliable delivery of electricity, providing opportunities to integrate intermittent renewable resources and to support unreliable and/or aging grid infrastructure. Within the RFB, porous carbonaceous electrodes facilitate the electrochemical reactions, distribute the flowing electrolyte, and conduct electrons. Understanding electrode reaction kinetics is crucial for improving RFB performance and lowering costs.

The challenges and opportunities of battery-powered flight.

Aircraft, and the aviation ecosystem in which they operate, are shaped by complex trades among technical requirements, economics and environmental concerns, all built on a foundation of safety. This Perspective explores the requirements of battery-powered aircraft and the chemistries that hold promise to enable them. The difference between flight and terrestrial needs and chemistries are highlighted.

Dynamics of Hydroxyl Anions Promotes Lithium Ion Conduction in Antiperovskite LiOHCl.

LiOHCl is an exemplar of the antiperovskite family of ionic conductors, for which high ionic conductivities have been reported, but in which the atomic-level mechanism of ion migration is unclear. The stable phase is both crystallographically defective and disordered, having ∼1/3 of the Li sites vacant, while the presence of the OH anion introduces the possibility of rotational disorder that may be coupled to cation migration. Here, complementary experimental and computational methods are applied to understand the relationship between the crystal chemistry and ionic conductivity in LiOHCl, which undergoes an orthorhombic to cubic phase transition near 311 K (≈38 °C) and coincides with the more than a factor of 10 change in ionic conductivity (from 1.

Non-Solvent Induced Phase Separation Enables Designer Redox Flow Battery Electrodes.

Porous carbonaceous electrodes are performance-defining components in redox flow batteries (RFBs), where their properties impact the efficiency, cost, and durability of the system. The overarching challenge is to simultaneously fulfill multiple seemingly contradictory requirements-i.e.

Energy storage emerging: A perspective from the Joint Center for Energy Storage Research.

Energy storage is an integral part of modern society. A contemporary example is the lithium (Li)-ion battery, which enabled the launch of the personal electronics revolution in 1991 and the first commercial electric vehicles in 2010. Most recently, Li-ion batteries have expanded into the electricity grid to firm variable renewable generation, increasing the efficiency and effectiveness of transmission and distribution.

Toward electrochemical synthesis of cement-An electrolyzer-based process for decarbonating CaCO while producing useful gas streams.

Cement production is currently the largest single industrial emitter of CO, accounting for ∼8% (2.8 Gtons/y) of global CO emissions. Deep decarbonization of cement manufacturing will require remediation of both the CO emissions due to the decomposition of CaCO to CaO and that due to combustion of fossil fuels (primarily coal) in calcining (∼900 °C) and sintering (∼1,450 °C).

Order-disorder transition in nano-rutile TiO anodes: a high capacity low-volume change Li-ion battery material.

Nano-sized particles of rutile TiO is a promising material for cheap high-capacity anodes for Li-ion batteries. It is well-known that rutile undergoes an irreversible order-disorder transition upon deep discharge. However, in the disordered state, the LiTiO material retains a high reversible ion-storage capacity of >200 mA h g.

Revisiting the cold case of cold fusion.

The 1989 claim of 'cold fusion' was publicly heralded as the future of clean energy generation. However, subsequent failures to reproduce the effect heightened scepticism of this claim in the academic community, and effectively led to the disqualification of the subject from further study. Motivated by the possibility that such judgement might have been premature, we embarked on a multi-institution programme to re-evaluate cold fusion to a high standard of scientific rigour.

Apparatus for operando x-ray diffraction of fuel electrodes in high temperature solid oxide electrochemical cells.

Characterizing electrochemical energy conversion devices during operation is an important strategy for correlating device performance with the properties of cell materials under real operating conditions. While operando characterization has been used extensively for low temperature electrochemical cells, these techniques remain challenging for solid oxide electrochemical cells due to the high temperatures and reactive gas atmospheres these cells require. Operando X-ray diffraction measurements of solid oxide electrochemical cells could detect changes in the crystal structure of the cell materials, which can be useful for understanding degradation process that limit device lifetimes, but the experimental capability to perform operando X-ray diffraction on the fuel electrodes of these cells has not been demonstrated.

Net-zero emissions energy systems.

Some energy services and industrial processes-such as long-distance freight transport, air travel, highly reliable electricity, and steel and cement manufacturing-are particularly difficult to provide without adding carbon dioxide (CO) to the atmosphere. Rapidly growing demand for these services, combined with long lead times for technology development and long lifetimes of energy infrastructure, make decarbonization of these services both essential and urgent. We examine barriers and opportunities associated with these difficult-to-decarbonize services and processes, including possible technological solutions and research and development priorities.

Molecular understanding of polyelectrolyte binders that actively regulate ion transport in sulfur cathodes.

Polymer binders in battery electrodes may be either active or passive. This distinction depends on whether the polymer influences charge or mass transport in the electrode. Although it is desirable to understand how to tailor the macromolecular design of a polymer to play a passive or active role, design rules are still lacking, as is a framework to assess the divergence in such behaviors.

Two-dimensional lithium diffusion behavior and probable hybrid phase transformation kinetics in olivine lithium iron phosphate.

Olivine lithium iron phosphate is a technologically important electrode material for lithium-ion batteries and a model system for studying electrochemically driven phase transformations. Despite extensive studies, many aspects of the phase transformation and lithium transport in this material are still not well understood. Here we combine operando hard X-ray spectroscopic imaging and phase-field modeling to elucidate the delithiation dynamics of single-crystal lithium iron phosphate microrods with long-axis along the [010] direction.

Low-profile self-sealing sample transfer flexure box.

A flexural bearing mechanism has enabled the development of a self-sealing box for protecting air sensitive samples during transfer between glove boxes, micro-machining equipment, and microscopy equipment. The simplicity and self-actuating feature of this design makes it applicable to many devices that operate under vacuum conditions. The models used to design the flexural mechanism are presented in detail.

Accommodating High Transformation Strains in Battery Electrodes via the Formation of Nanoscale Intermediate Phases: Operando Investigation of Olivine NaFePO.

Virtually all intercalation compounds exhibit significant changes in unit cell volume as the working ion concentration varies. NaFePO (0 < x < 1, NFP) olivine, of interest as a cathode for sodium-ion batteries, is a model for topotactic, high-strain systems as it exhibits one of the largest discontinuous volume changes (∼17% by volume) during its first-order transition between two otherwise isostructural phases. Using synchrotron radiation powder X-ray diffraction (PXD) and pair distribution function (PDF) analysis, we discover a new strain-accommodation mechanism wherein a third, amorphous phase forms to buffer the large lattice mismatch between primary phases.

Engineering the Transformation Strain in LiMnyFe1-yPO4 Olivines for Ultrahigh Rate Battery Cathodes.

Alkali ion intercalation compounds used as battery electrodes often exhibit first-order phase transitions during electrochemical cycling, accompanied by significant transformation strains. Despite ∼30 years of research into the behavior of such compounds, the relationship between transformation strain and electrode performance, especially the rate at which working ions (e.g.

Three-Dimensional Growth of Li2S in Lithium-Sulfur Batteries Promoted by a Redox Mediator.

During the discharge of a lithium-sulfur (Li-S) battery, an electronically insulating 2D layer of Li2S is electrodeposited onto the current collector. Once the current collector is enveloped, the overpotential of the cell increases, and its discharge is arrested, often before reaching the full capacity of the active material. Guided by a new computational platform known as the Electrolyte Genome, we advance and apply benzo[ghi]peryleneimide (BPI) as a redox mediator for the reduction of dissolved polysulfides to Li2S.

Identification of Li-Ion Battery SEI Compounds through (7)Li and (13)C Solid-State MAS NMR Spectroscopy and MALDI-TOF Mass Spectrometry.

Solid-state (7)Li and (13)C MAS NMR spectra of cycled graphitic Li-ion anodes demonstrate SEI compound formation upon lithiation that is followed by changes in the SEI upon delithiation. Solid-state (13)C DPMAS NMR shows changes in peaks associated with organic solvent compounds (ethylene carbonate and dimethyl carbonate, EC/DMC) upon electrochemical cycling due to the formation of and subsequent changes in the SEI compounds. Solid-state (13)C NMR spin-lattice (T1) relaxation time measurements of lithiated Li-ion anodes and reference poly(ethylene oxide) (PEO) powders, along with MALDI-TOF mass spectrometry results, indicate that large-molecular-weight polymers are formed in the SEI layers of the discharged anodes.

Mechanism and Kinetics of Li2S Precipitation in Lithium-Sulfur Batteries.

The kinetics of Li2 S electrodeposition onto carbon in lithium-sulfur batteries are characterized. Electrodeposition is found to be dominated by a 2D nucleation and growth process with rate constants that depend strongly on the electrolyte solvent. Nucleation is found to require a greater overpotential than growth, which results in a morphology that is dependent on the discharge rate.

Mitigating mechanical failure of crystalline silicon electrodes for lithium batteries by morphological design.

Although crystalline silicon (c-Si) anodes promise very high energy densities in Li-ion batteries, their practical use is complicated by amorphization, large volume expansion and severe plastic deformation upon lithium insertion. Recent experiments have revealed the existence of a sharp interface between crystalline Si (c-Si) and the amorphous LixSi alloy during lithiation, which propagates with a velocity that is orientation dependent; the resulting anisotropic swelling generates substantial strain concentrations that initiate cracks even in nanostructured Si. Here we describe a novel strategy to mitigate lithiation-induced fracture by using pristine c-Si structures with engineered anisometric morphologies that are deliberately designed to counteract the anisotropy in the crystalline/amorphous interface velocity.