Development of ceramic lithium ion electrolytes for high performance batteries

292 p.The electromobility revolution has promoted research unto cutting-edge battery concepts with high energy and power densities, with paramount premium on safety. The electrolyte in these devices has to be insulating to electrons but highly conductive to ions with a wide range of electrochemical stability during operation. Using a solid electrolyte will allow the use of lithium metal as an anode, by blocking the Li dendrite formation, and the exploration of high-voltage cathode materials. In this regard, the use of ceramic oxides can also provide safer, low cost devices with the possibility of miniaturization that would boost the use of batteries in large scale applications.This PhD project aimed to understand the relationship between crystal structure and microstructure with Li-mobility mechanisms within garnet-structured oxide materials. An engineered material with superior ionic conductivity has been developed (1 mS/cm), and its application in a full-cell battery investigated in detail.CIC Energigun

Development of ceramic lithium ion electrolytes for high performance batteries

292 p.The electromobility revolution has promoted research unto cutting-edge battery concepts with high energy and power densities, with paramount premium on safety. The electrolyte in these devices has to be insulating to electrons but highly conductive to ions with a wide range of electrochemical stability during operation. Using a solid electrolyte will allow the use of lithium metal as an anode, by blocking the Li dendrite formation, and the exploration of high-voltage cathode materials. In this regard, the use of ceramic oxides can also provide safer, low cost devices with the possibility of miniaturization that would boost the use of batteries in large scale applications.This PhD project aimed to understand the relationship between crystal structure and microstructure with Li-mobility mechanisms within garnet-structured oxide materials. An engineered material with superior ionic conductivity has been developed (1 mS/cm), and its application in a full-cell battery investigated in detail.CIC Energigun

Grid-Connected Energy Storage Systems: State-of-the-Art and Emerging Technologies

High penetration of renewable energy resources in the power system results in various new challenges for power system operators. One of the promising solutions to sustain the quality and reliability of the power system is the integration of energy storage systems (ESSs). This article investigates the current and emerging trends and technologies for grid-connected ESSs. Different technologies of ESSs categorized as mechanical, electrical, electrochemical, chemical, and thermal are briefly explained. Especially, a detailed review of battery ESSs (BESSs) is provided as they are attracting much attention owing, in part, to the ongoing electrification of transportation. Then, the services that grid-connected ESSs provide to the grid are discussed. Grid connection of the BESSs requires power electronic converters. Therefore, a survey of popular power converter topologies, including transformer-based, transformerless with distributed or common dc-link, and hybrid systems, along with some discussions for implementing advanced grid support functionalities in the BESS control, is presented. Furthermore, the requirements of new standards and grid codes for grid-connected BESSs are reviewed for several countries around the globe. Finally, emerging technologies, including flexible power control of photovoltaic systems, hydrogen, and second-life batteries from electric vehicles, are discussed in this article.This work was supported in part by the Office of Naval Research Global under Grant N62909-19-1-2081, in part by the National Research Foundation of Singapore Investigatorship under Award NRFI2017-08, and in part by the I2001E0069 Industrial Alignment Funding. (Corresponding author: Josep Pou.

Hydrogen-Bonding Interactions in Hybrid Aqueous/Nonaqueous Electrolytes Enable Low-Cost and Long-Lifespan Sodium-Ion Storage.

Although "water-in-salt" electrolytes have opened a new pathway to expand the electrochemical stability window of aqueous electrolytes, the electrode instability and irreversible proton co-insertion caused by aqueous media still hinder the practical application, even when using exotic fluorinated salts. In this study, an accessible hybrid electrolyte class based on common sodium salts is proposed, and crucially an ethanol-rich media is introduced to achieve highly stable Na-ion electrochemistry. Here, ethanol exerts a strong hydrogen-bonding effect on water, simultaneously expanding the electrochemical stability window of the hybridized electrolyte to 2.5 V, restricting degradation activities, reducing transition metal dissolution from the cathode material, and improving electrolyte-electrode wettability. The binary ethanol-water solvent enables the impressive cycling of sodium-ion batteries based on perchlorate, chloride, and acetate electrolyte salts. Notably, a Na0.44MnO2 electrode exhibits both high capacity (81 mAh g-1) and a remarkably long cycle life >1000 cycles at 100 mA g-1 (a capacity decay rate per cycle of 0.024%) in a 1 M sodium acetate system. The Na0.44MnO2/Zn full cells also show excellent cycling stability and rate capability in a wide temperature range. The gained understanding of the hydrogen-bonding interactions in the hybridized electrolyte can provide new battery chemistry guidelines in designing promising candidates for developing low-cost and long-lifespan batteries based on other (Li+, K+, Zn2+, Mg2+, and Al3+) systems

Undesired reactions in aqueous rechargeable zinc ion batteries

Rechargeable zinc-ion batteries (RZIBs) utilizing aqueous electrolytes can offer high safety, low cost, and fast charge/discharge ratings for large-scale energy storage. The use of water as electrolyte solvent facilitates low cost, facile processing, reduced safety concerns, and fast ion kinetics. However, free water molecules also instigate many simultaneously occurring undesired reactions in the RZIB system, leading to capacity fade and limited operational lifetime. Here, our review traces each undesired reaction and its cascade of detrimental ramifications on RZIB cycling. We discuss balancing merits, reported strategies, and future perspectives to mitigate these undesired reactions and further improve the RZIBs’ operational lifetimes.National Research Foundation (NRF)Submitted/Accepted versionThis work was funded by the National Research Foundation of Singapore Investigatorship Award Number NRFI2017-08

Trans-influence of nitrogen-and sulfur-containing ligands in trans-platinum complexes: A density functional theory study

Transplatin complexes with N-or S-containing ligands were modeled in silico. We performed density functional theory calculations using the B3LYP exchange-correlation functional as incorporated in the Gaussian03 software package. The 6-311+G(d,p) basis set was used for first-row elements, and the LanL2DZ with effective core potential (ECP) basis set was used for platinum. The various neutral N-or S-containing ligands do not give rise to considerable variations in the trans-bond lengths and strengths. The reactions leading to complex formation also yield close net energy values. Nevertheless, Pt complexes with anionic thiolate (CH3S-) ligand are significantly more energetically stable by at least ∼5eV (∼115kcalmol-1 or ∼484kJmol-1) compared to transplatin complexes with other ligands. An examination of the net energetic stabilities and dipole moments of transplatin complexes with N-and S-ligands led us to hypothesize adenine to be the most suitable candidate among naturally occurring organic ligands (X) for the development of trans-Pt(NR)(NR′)Cl(X) anticancer agent. © 2009 IOP Publishing Ltd

Enabling Al-metal anodes for aqueous electrochemical cells by using low-cost eutectic mixtures as artificial protective interphase

Elemental aluminum is an exciting battery anode material due to its high abundance and volumetric capacity (8040 mAh cm−3). However, it tends to form a stubborn surface oxide layer that blocks ion transport through the electrode–electrolyte interphase and stops battery cyclability. To circumvent this problem, here we engineer an artificial protective barrier layer on metallic Al by using AlCl3 + urea and AlCl3 + triethylamine hydrochloride eutectic coating formulations. We find both coatings provide significantly facile ion migration kinetics at the anode/electrolyte interface, enabling a drastic reduction in anodic electroplating/stripping overpotentials, but AlCl3 + urea is superior. Using depth-profiling XPS spectroscopy and impedance studies, we find that the AlCl3 + urea derived artificial interphase is also stable in ambient air, affording extended protection for metallic Al anodes from air-oxidation in the form of a battery electrode SEI. We demo the eutectic-treated Al anode (UTAl) based on a FeHCF | 2 m AlTFS | UTAl full cell chemistry and obtain a stable battery performance of ∼ 60 Wh kg−1 over 100 cycles. Our study promotes the strategic viability of using facile, inexpensive reagent treatments to enable the application of water-based electrolytes for rechargeable Al-ion batteries, and specifically encourages systematic exploration of analogue coating formulations using our anode enhancement protocol for similar high-capacity metal/alloy battery chemistries.National Research Foundation (NRF)Submitted/Accepted versionThis work was financially supported by the National Research Foundation of Singapore (NRF) Investigatorship Award Number NRF-NRFI2017-08

Emerging rechargeable aqueous aluminum ion battery : status, challenges, and outlooks

Aluminum ion battery (AIB) technology is an exciting alternative for post-lithium energy storage. AIBs based on ionic liquids have enabled advances in both cathode material development and fundamental understanding on mechanisms. Recently, unlocking chemistry in rechargeable aqueous aluminum ion battery (AAIB) provides impressive prospects in terms of kinetics, cost, safety considerations, and ease of operation. To review the progress on AAIB, we discuss the critical issues on aluminum electrochemistry in aqueous system, cathode material design to overcome the drawbacks by multivalent aluminum ions, and challenges on electrolyte design, aluminum stripping/plating, solid-electrolyte interface (SEI) formation, and design of cathode materials. This review aims to stimulate exploration of high-performance AAIB and rationalize feasibility grounded on underlying reaction mechanisms.National Research Foundation (NRF)Published versionNational Research Foundation of Singapore (NRF) Investigatorship Award Number NRFI2017-08/NRF2016NRF-NRFI001-22

Rechargeable Al-metal aqueous battery using NaMnHCF as cathode : investigating the role of coated-Al anode treatments for supe-rior battery cycling performance

Rechargeable Al-ion aqueous batteries (AIABs) are emerging contenders for massive battery systems due to economic, abundance, environmental, and safety advantages. However, the high capacity of metallic-Al remains untapped due to native oxide barrier formation. Engineering oxide removal by treating Al metal with an ionic liquid mixture solves this problem but the role of this treated-Al (TAl) in influencing full-cell battery performance is not yet fully understood. At the same time, the stability and compatibility of the coating layer applied on Al metal remain unexplored for long-term handling in full-cell assembly lines. Here, we explore the above two aspects of TAl in the context of a full-cell AIAB. First, a highly stable cathode material, NMnHCF, is demonstrated to successfully store an Al-ion by reversibly transforming from the monoclinic to tetragonal phase. A high energy density surpassing previous equivalent reports has been reported. Second, it is revealed that combinations of electrolyte–TAl pairings significantly influence the overall battery performance, wherein electrolyte conductivity influences the Al plating/stripping overpotential, which in turn dictates the overall battery performance. We also document that chlorinated coatings on TAl are stable under ambient atmosphere for at least 40 h and prevent reoxidation of the bulk aluminum metal during battery fabrication and electrochemical cyclingNational Research Foundation (NRF)Accepted versionThis work was financially supported by the National Research Foundation of Singapore (NRF) Investigatorship Award Number NRFI2017-08/NRF2016NRF-NRFI001-22