Mariyappan Sathiya

Bio: Mariyappan Sathiya is an academic researcher from Collège de France. The author has contributed to research in topics: Lithium & Materials science. The author has an hindex of 17, co-authored 18 publications receiving 2699 citations. Previous affiliations of Mariyappan Sathiya include University of Picardie Jules Verne & Indian Institute of Technology Madras.

Reversible anionic redox chemistry in high-capacity layered-oxide electrodes

Abstract: Li-ion batteries have contributed to the commercial success of portable electronics and may soon dominate the electric transportation market provided that major scientific advances including new materials and concepts are developed. Classical positive electrodes for Li-ion technology operate mainly through an insertion-deinsertion redox process involving cationic species. However, this mechanism is insufficient to account for the high capacities exhibited by the new generation of Li-rich (Li1+xNiyCozMn(1−x−y−z)O2) layered oxides that present unusual Li reactivity. In an attempt to overcome both the inherent composition and the structural complexity of this class of oxides, we have designed structurally related Li2Ru1−ySnyO3 materials that have a single redox cation and exhibit sustainable reversible capacities as high as 230 mA h g−1. Moreover, they present good cycling behaviour with no signs of voltage decay and a small irreversible capacity. We also unambiguously show, on the basis of an arsenal of characterization techniques, that the reactivity of these high-capacity materials towards Li entails cumulative cationic (Mn+→M(n+1)+) and anionic (O2−→O22−) reversible redox processes, owing to the d-sp hybridization associated with a reductive coupling mechanism. Because Li2MO3 is a large family of compounds, this study opens the door to the exploration of a vast number of high-capacity materials.

Origin of voltage decay in high-capacity layered oxide electrodes

Abstract: Although Li-rich layered oxides (Li1+xNiyCozMn1−x−y−zO2 > 250 mAh g−1) are attractive electrode materials providing energy densities more than 15% higher than today’s commercial Li-ion cells, they suffer from voltage decay on cycling. To elucidate the origin of this phenomenon, we employ chemical substitution in structurally related Li2RuO3 compounds. Li-rich layered Li2Ru1−yTiyO3 phases with capacities of ~240 mAh g−1 exhibit the characteristic voltage decay on cycling. A combination of transmission electron microscopy and X-ray photoelectron spectroscopy studies reveals that the migration of cations between metal layers and Li layers is an intrinsic feature of the charge–discharge process that increases the trapping of metal ions in interstitial tetrahedral sites. A correlation between these trapped ions and the voltage decay is established by expanding the study to both Li2Ru1−ySnyO3 and Li2RuO3; the slowest decay occurs for the cations with the largest ionic radii. This effect is robust, and the finding provides insights into new chemistry to be explored for developing high-capacity layered electrodes that evade voltage decay.

High Performance Li2Ru1–yMnyO3 (0.2 ≤ y ≤ 0.8) Cathode Materials for Rechargeable Lithium-Ion Batteries: Their Understanding

Abstract: Understanding the origin of the high capacity displayed by Li2MnO3–LiMO2 (M = Ni, Co) composites is essential for improving their cycling and rate capability performances. To address this issue, the Li2Ru1–yMnyO3 series between the iso-structural layered end-members Li2MnO3 and Li2RuO3 was investigated. A complete solid solution was found, with the 0.4 ≤ y ≤ 0.6 members showing sustainable reversible capacities exceeding 220 mAh·g–1 centered around 3.6 V vs Li+/Li. The voltage–composition profiles display a plateau on the first charge as compared to an S-type curve on subsequent discharge which is maintained on the following charges/discharges, with therefore a lowering of the average voltage. We show this profile to evolve upon long cycling due to a structural phase transition as deduced from XRD measurements. Finally we demonstrate, via XPS measurements, the oxidation and reduction of ruthenium (Ru5+/Ru4+) during cycling together with a partial activity of the Mn4+/Mn3+ redox couple. Moreover, we provid...

Electron paramagnetic resonance imaging for real-time monitoring of Li-ion batteries

Abstract: Batteries for electrical storage are central to any future alternative energy paradigm. The ability to probe the redox mechanisms occurring at electrodes during their operation is essential to improve battery performances. Here we present the first report on Electron Paramagnetic Resonance operando spectroscopy and in situ imaging of a Li-ion battery using Li 2 Ru 0.75 Sn 0.25 O 3 , a high-capacity (4270 mAh g A 1) Li-rich layered oxide, as positive electrode. By monitoring operando the electron paramagnetic resonance signals of Ru 5 þ and paramagnetic oxygen species, we unambiguously prove the formation of reversible (O 2) n A species that contribute to their high capacity. In addition, we visualize by imaging with micrometric resolution the plating/stripping of Li at the negative electrode and highlight the zones of nucleation and growth of Ru 5 þ /oxygen species at the positive electrode. This efficient way to locate 'electron'-related phenomena opens a new area in the field of battery characterization that should enable future breakthroughs in battery research.

Reversible anionic redox chemistry inhigh-capacity layered-oxide electrodes

Abstract: Li-ion batteries have contributed to the commercial success of portable electronics and may soon dominate the electric transportation market provided that major scientific advances including new materials and concepts are developed. Classical positive electrodes for Li-ion technology operate mainly through an insertion–deinsertion redox process involving cationic species. However, this mechanism is insufficient to account for the high capacities exhibited by the new generation of Li-rich (Li1CxNiyCozMn(1

Towards greener and more sustainable batteries for electrical energy storage

Abstract: Energy storage using batteries offers a solution to the intermittent nature of energy production from renewable sources; however, such technology must be sustainable. This Review discusses battery development from a sustainability perspective, considering the energy and environmental costs of state-of-the-art Li-ion batteries and the design of new systems beyond Li-ion. Images: batteries, car, globe: © iStock/Thinkstock.

The path towards sustainable energy

Abstract: Civilization continues to be transformed by our ability to harness energy beyond human and animal power. A series of industrial and agricultural revolutions have allowed an increasing fraction of the world population to heat and light their homes, fertilize and irrigate their crops, connect to one another and travel around the world. All of this progress is fuelled by our ability to find, extract and use energy with ever increasing dexterity. Research in materials science is contributing to progress towards a sustainable future based on clean energy generation, transmission and distribution, the storage of electrical and chemical energy, energy efficiency, and better energy management systems.

The Development and Future of Lithium Ion Batteries

Abstract: This year, the battery industry celebrates the 25th anniversary of the introduction of the lithium ion rechargeable battery by Sony Corporation. The discovery of the system dates back to earlier work by Asahi Kasei in Japan, which used a combination of lower temperature carbons for the negative electrode to prevent solvent degradation and lithium cobalt dioxide modified somewhat from Goodenough’s earlier work. The development by Sony was carried out within a few years by bringing together technology in film coating from their magnetic tape division and electrochemical technology from their battery division. The past 25 years has shown rapid growth in the sales and in the benefits of lithium ion in comparison to all the earlier rechargeable battery systems. Recent work on new materials shows that there is a good likelihood that the lithium ion battery will continue to improve in cost, energy, safety and power capability and will be a formidable competitor for some years to come. © The Author(s) 2016. Published by ECS. This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 License (CC BY, http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse of the work in any medium, provided the original work is properly cited. [DOI: 10.1149/2.0251701jes] All rights reserved.

Activating lattice oxygen redox reactions in metal oxides to catalyse oxygen evolution

Abstract: Understanding how materials that catalyse the oxygen evolution reaction (OER) function is essential for the development of efficient energy-storage technologies. The traditional understanding of the OER mechanism on metal oxides involves four concerted proton-electron transfer steps on metal-ion centres at their surface and product oxygen molecules derived from water. Here, using in situ 18O isotope labelling mass spectrometry, we provide direct experimental evidence that the O2 generated during the OER on some highly active oxides can come from lattice oxygen. The oxides capable of lattice-oxygen oxidation also exhibit pH-dependent OER activity on the reversible hydrogen electrode scale, indicating non-concerted proton-electron transfers in the OER mechanism. Based on our experimental data and density functional theory calculations, we discuss mechanisms that are fundamentally different from the conventional scheme and show that increasing the covalency of metal-oxygen bonds is critical to trigger lattice-oxygen oxidation and enable non-concerted proton-electron transfers during OER.