Ronald J. Hoffman

Bio: Ronald J. Hoffman is an academic researcher from Dow Chemical Company. The author has contributed to research in topics: Electrolyte & Intercalation (chemistry). The author has an hindex of 6, co-authored 8 publications receiving 614 citations.

Nonaqueous Electrochemistry of Magnesium Applications to Energy Storage

Abstract: Research leading to the construction of an ambient temperature rechargeable magnesium battery based on organic electrolytes and positive electrodes capable of reversible intercalation of Mg+2 ions is discussed. The number of combinations of solvent, solute, and intercalation cathode which give reasonable battery performance is much more limited for Mg than for alkali metals. The only electrolytes which allowed Mg dissolution and deposition were solutions of organomagnesium compounds in ethers or tertiary amines; many of these were unstable in the presence of transition metal oxides or sulfides which were found to function acceptably as intercalation electrodes. Possible directions for future research which could solve these problems are discussed, as well as theoretical aspects of magnesium compound behavior in nonaqueous solvents.

Alkaline earth metal anode-containing cell having electrolyte of organometallic alkaline earth metal salt and organic solvent

Abstract: Alkaline earth metal anode cells having an intercalation cathode, a nonaqueous liquid electrolyte comprising (a) an organic solvent, for instance, an ether, an ester, a sulfone, an organic sulfide, an organic sulfate, a tertiary amine, an organic nitrite, and an organic nitrate, and (b) at least one of an electrolytically active alkaline earth metal salt comprising an organometallic alkaline earth metal salt represented by the formula: ##STR1## wherein Z is selected from the group consisting of boron and aluminum; X is selected from the group consisting of phosphorus and arsenic; M is an alkaline earth metal; and in which R1 -R6 are radicals independently selected from the following groups: alkyl, aryl, alkaryl, aralkyl, alkenyl, cycloalkyl, allyl, heterocyclic alkyl, and cyano, with the proviso that R1 -R6 cannot be all alkyl or all aryl and triarylalkylborate or aluminate anions, and trialkylarylborate or aluminate anions are excluded and M represents an alkaline earth metal.

Nonaqueous Electrochemistry of Magnesium. Applications to Energy Storage.

Abstract: Research leading to the construction of an ambient temperature rechargeable magnesium battery based on organic electrolytes and positive electrodes capable of reversible intercalation of Mg+2 ions is discussed. The number of combinations of solvent, solute, and intercalation cathode which give reasonable battery performance is much more limited for Mg than for alkali metals. The only electrolytes which allowed Mg dissolution and deposition were solutions of organomagnesium compounds in ethers or tertiary amines; many of these were unstable in the presence of transition metal oxides or sulfides which were found to function acceptably as intercalation electrodes. Possible directions for future research which could solve these problems are discussed, as well as theoretical aspects of magnesium compound behavior in nonaqueous solvents.

Novel ceramic-metal compounds

Abstract: Novel ceramic-metal intercalation compounds useful in the formation of densified ceramic-metal articles are prepared, for instance, by exposing a ceramic to an organometallic compound in a low dielectric solvent. The use of the ceramic-metal compounds in the formation of articles by densification allows achievement of densified compositions having at least one of increased density, hardness, and toughness.

Process for the preparation of asymmetrical alkaline earth metal organoborates, organoaluminates, organoarsenates, and organophosphates

Abstract: Process for the preparation of asymmetrical alkaline earth metal organoborates and organoaluminates represented by the formula I: ##STR1## and asymmetrical alkaline earth metal organoarsenates and organophosphates represented by the formula II: ##STR2## wherein Z is selected from the group consisting of boron and aluminum; X is selected from the group consisting of phosphorus and arsenic; M is an alkaline earth metal; and in which R 1 -R 6 are independently selected from alkyl, aryl, alkaryl, aralkyl, alkenyl, cycloalkyl, and cyano with the proviso that R 1 -R 6 are not all the same.

Toward Safe Lithium Metal Anode in Rechargeable Batteries: A Review.

Abstract: The lithium metal battery is strongly considered to be one of the most promising candidates for high-energy-density energy storage devices in our modern and technology-based society. However, uncontrollable lithium dendrite growth induces poor cycling efficiency and severe safety concerns, dragging lithium metal batteries out of practical applications. This review presents a comprehensive overview of the lithium metal anode and its dendritic lithium growth. First, the working principles and technical challenges of a lithium metal anode are underscored. Specific attention is paid to the mechanistic understandings and quantitative models for solid electrolyte interphase (SEI) formation, lithium dendrite nucleation, and growth. On the basis of previous theoretical understanding and analysis, recently proposed strategies to suppress dendrite growth of lithium metal anode and some other metal anodes are reviewed. A section dedicated to the potential of full-cell lithium metal batteries for practical applicatio...

Promise and reality of post-lithium-ion batteries with high energy densities

Abstract: Energy density is the main property of rechargeable batteries that has driven the entire technology forward in past decades. Lithium-ion batteries (LIBs) now surpass other, previously competitive battery types (for example, lead–acid and nickel metal hydride) but still require extensive further improvement to, in particular, extend the operation hours of mobile IT devices and the driving mileages of all-electric vehicles. In this Review, we present a critical overview of a wide range of post-LIB materials and systems that could have a pivotal role in meeting such demands. We divide battery systems into two categories: near-term and long-term technologies. To provide a realistic and balanced perspective, we describe the operating principles and remaining issues of each post-LIB technology, and also evaluate these materials under commercial cell configurations. Post-lithium-ion batteries are reviewed with a focus on their operating principles, advantages and the challenges that they face. The volumetric energy density of each battery is examined using a commercial pouch-cell configuration to evaluate its practical significance and identify appropriate research directions.

Prototype systems for rechargeable magnesium batteries

Abstract: The thermodynamic properties of magnesium make it a natural choice for use as an anode material in rechargeable batteries, because it may provide a considerably higher energy density than the commonly used lead-acid and nickel-cadmium systems Moreover, in contrast to lead and cadmium, magnesium is inexpensive, environmentally friendly and safe to handle But the development of Mg batteries has been hindered by two problems First, owing to the chemical activity of Mg, only solutions that neither donate nor accept protons are suitable as electrolytes; but most of these solutions allow the growth of passivating surface films, which inhibit any electrochemical reaction Second, the choice of cathode materials has been limited by the difficulty of intercalating Mg ions in many hosts Following previous studies of the electrochemistry of Mg electrodes in various non-aqueous solutions, and of a variety of intercalation electrodes, we have now developed rechargeable Mg battery systems that show promise for applications The systems comprise electrolyte solutions based on Mg organohaloaluminate salts, and Mg(x)Mo3S4 cathodes, into which Mg ions can be intercalated reversibly, and with relatively fast kinetics We expect that further improvements in the energy density will make these batteries a viable alternative to existing systems

Mg rechargeable batteries: an on-going challenge

Abstract: The first working Mg rechargeable battery prototypes were ready for presentation about 13 years ago after two breakthroughs. The first was the development of non-Grignard Mg complex electrolyte solutions with reasonably wide electrochemical windows in which Mg electrodes are fully reversible. The second breakthrough was attained by demonstrating high-rate Mg cathodes based on Chevrel phases. These prototypes could compete with lead–acid or Ni–Cd batteries in terms of energy density, very low self-discharge, a wide temperature range of operation, and an impressive prolonged cycle life. However, the energy density and rate capability of these Mg battery prototypes were not attractive enough to commercialize them. Since then we have seen gradual progress in the development of better electrolyte solutions, as well as suggestions of new cathodes. In this article we review the recent accumulated experience, understandings, new strategies and materials, in the continuous R&D process of non-aqueous Mg batteries. This paper provides a road-map of this field during the last decade.