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1. Quantifying the Aging of Lithium-Ion Pouch Cells Using Pressure Sensors

   Nayfeh, Y; Vittitoe, JC; Li, X (September 2024, Batteries)

   Understanding the behavior of pressure increases in lithium-ion (Li-ion) cells is essential for prolonging the lifespan of Li-ion battery cells and minimizing the safety risks associated with cell aging. This work investigates the effects of C-rates and temperature on pressure behavior in commercial lithium cobalt oxide (LCO)/graphite pouch cells. The battery is volumetrically constrained, and the mechanical pressure response is measured using a force gauge as the battery is cycled. The effect of the C-rate (1C, 2C, and 3C) and ambient temperature (10 ◦C, 25 ◦C, and 40 ◦C) on the increase in battery pressure is investigated. By analyzing the change in the minimum, maximum, and pressure difference per cycle, we identify and discuss the effects of different factors (i.e., SEI layer damage, electrolyte decomposition, lithium plating) on the pressure behavior. Operating at high C-rates or low temperatures rapidly increases the residual pressure as the battery is cycled. The results suggest that lithium plating is predominantly responsible for battery expansion and pressure increase during the cycle aging of Li-ion cells rather than electrolyte decomposition. Electrochemical impedance spectroscopy (EIS) measurements can support our conclusions. Postmortem analysis of the aged cells was performed using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) to confirm the occurrence of lithium plating and film growth on the anodes of the aged cells. This study demonstrates that pressure measurements can provide insights into the aging mechanisms of Li-ion batteries and can be used as a reliable predictor of battery degradation. 

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2. Elucidating the role of cathode identity: Voltage-dependent reversibility of anode-free batteries

   https://doi.org/10.1016/j.chempr.2024.06.008  

   Kwon, Yongbeom; Svirinovsky-Arbeli, Asya; Hestenes, Julia C; Buitrago_Botero, Pablo J; Corpus, Kaitlin_Rae M; Lepucki, Piotr; Pecher, Oliver; Marbella, Lauren E (October 2024, Chem)

   The cathode material in a lithium (Li) battery determines the system cost, energy density, and thermal stability. In anode-free batteries, the cathode also serves as the source of Li for electrodeposition, thus impacting the reversibility of plating and stripping. Here, we show that the reason LiNi0.8Mn0.1Co0.1O2 (NMC811) cathodes deliver lower Coulombic efficiencies than LiFePO4 (LFP) is the formation of tortuous Li deposits, acidic species in the electrolyte, and accumulation of “dead” Li0. Batteries containing an LFP cathode generate dense Li deposits that can be reversibly stripped, but Li is lost to the solid electrolyte interphase (SEI) and corrosion according to operando 7Li NMR, which seemingly “revives” dead Li0. X-ray photoelectron spectroscopy (XPS) and in situ 19F/1H NMR indicate that these differences arise because upper cutoff voltage alters electrolyte decomposition, where low-voltage LFP cells prevent anodic decomposition, ultimately mitigating the formation of protic species that proliferate upon charging NMC811. 

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3. LiAlO2/LiAl5O8 thin films derived from flame synthesized nanopowders as a potential electro-lyte and coating materials for all solid-state batteries (ASSBs)

   https://doi.org/DOI:10.1021/acsami.0c13021  

   E. Temeche, S. Indris (July 2020, ACS applied materials interfaces)

   null (Ed.)

   Recently, γ-LiAlO2 has attracted considerable attention as a coating in Li-ion battery electrodes. However, its potential as a Li+ ceramic electrolyte is limited due to its poor ionic conductivity (<10−10 S cm−1). Here, we demonstrate an effective method of processing LiAlO2 membranes (<50 μm) using nanopowders (NPs) produced via liquid-feed flame spray pyrolysis(LF-FSP). Membranes consisting of selected mixtures of lithium aluminate polymorphs and Li contents were processed byconventional tape casting of NPs followed by thermocompressionof the green films (100 °C/10 kpsi/10 min). The sintered greenfilms (1100 °C/2 h/air) present a mixture of LiAlO2 (∼72 wt %)and LiAl5O8 (∼27 wt %) phases, offering ionic conductivities (>10−6 S cm−1) at ambient with an activation energy of 0.5 eV. This greatly increases their potential utility as ceramic electrolytes for all-solid-state batteries, which could simplify battery designs, significantly reduce costs, and increase their safety. Furthermore, a solid-state Li/Li3.1AlO2/Li symmetric cell was assembled and galvanostatically cycled at 0.375 mA cm−2 current density, exhibiting a transference number ≈ 1. 

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4. Life Aging Effect as a Conditioning Process that Regulates the Performance of the Halogen-Free Mg Electrolyte

   Eslam Sheha, Shengqi Fan (June 2023, Langmuir)

   Studying the interplay of the electrochemical performance and the electrolyte conditioning process is crucial for building an efficient magnesium battery. In this work, we use halogen-free electrolyte (HFE) based on Mg(NO3)2 in acetonitrile (ACN) and tetraethylene glycol dimethyl ether (G4) to study the effect of the aging time calendar on its electrochemical properties. The characterization techniques confirm apparent changes occurring in the bulk speciation and the Mg2+ solvation barrier of the aging HFE relative to the as-prepared fresh HFE. The overpotential of Mg plating/stripping and bulk resistance of aging HFE is reduced relative to the as-prepared fresh HFE. Mg-S cells using aged HFE deliver high specific capacities (586 mAh/g), higher Coulombic efficiencies, and higher cycle life (up to 30 cycles at 25 °C) relative to Mg-S cells with fresh HFE that deliver a specific capacity of ~ 535 mAh g-1, low coulombic efficiency, and short cycle life; at a current density of 0.02 mA cm−2. The present findings provide a new concept describing how the aging process regulates the electrochemical performance of HFE and enhance the cycle life of Mg-S batteries. 

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5. An Algorithmic Safety VEST For Li-ion Batteries During Fast Charging

   Peyman Mohtat, Sravan Pannala (October 2021, 2021 Modeling, Estimation and Control Conference)

   null (Ed.)

   Fast charging of lithium-ion batteries is crucial to increase desirability for consumers and hence accelerate the adoption of electric vehicles. A major barrier to shorter charge times is the accelerated aging of the battery at higher charging rates, which can be driven by lithium plating, increased solid electrolyte interphase growth due to elevated temperatures, and particle cracking due to mechanical stress. Lithium plating depends on the overpotential of the negative electrode, and mechanical stress depends on the concentration gradient, both of which cannot be measured directly. Techniques based on physics-based models of the battery and optimal control algorithms have been developed to this end. While these methods show promise in reducing degradation, their optimization algorithms' complexity can limit their implementation. In this paper, we present a method based on the constant current constant voltage (CC-CV) charging scheme, called CC-CVησT (VEST). The new approach is simpler to implement and can be used with any model to impose varying levels of constraints on variables pertinent to degradation, such as plating potential and mechanical stress. We demonstrate the new CC-CVησT charging using an electrochemical model with mechanical and thermal effects included. Furthermore, we discuss how uncertainties can be accounted for by considering safety margins for the plating and stress constraints. 

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