Electrochemical Study of Functional Additives for Li-Ion Batteries

Abstract

In the battery industry, the performance of lithium-ion batteries operating at a high voltage is enhanced by utilizing functional additives in electrolytes to achieve higher energy densities and longer lifetimes. These additives chemically stabilize the electrolyte and aid in the formation of a stable cathode electrolyte interphase (CEI). In this paper, the investigation of oxidative potentials of more than 100 additives, using density functional theory calculations to determine the best candidates for CEI formation, is reported. The method was validated by comparing the calculated oxidation potentials and the experimental data obtained using linear sweep voltammetry based on the evaluation of 18 candidates. Further electrochemical studies (AC impedance and cycling stability) on six selected additives were conducted. Among the tested additives, the addition of quinacridone at 0.03% weight concentration resulted in the formation of a less resistive surface film on the cathode in Li/Ni0.5Mn0.3Co0.2O2 coin cells. Moreover, the capacity retention in Gr/Ni0.5Mn0.3Co0.2O coin cells increased from 62% to 77% after 200 cycles at 1C and approximately 4.4 V. The derived results suggest that the combination of the oxidation potential prediction with impedance study could be used as a powerful tool to properly and efficiently select CEI-forming additive candidates for improved battery performance.

Best practices for incremental capacity analysis

“…This publication will address the lower level by providing a guide on how to make sense of the voltage changes. ICA could not only be used to analyze aging (cycle or calendar) but also electrochemical milling (Dubarry et al, 2014), decomposition of additives (Khodr et al, 2020), lithium plating (Anseán et al, 2017;Chen et al, 2022), the impact of temperature (Dubarry et al, 2013;Fly et al, 2022;Gauthier et al, 2022), inhomogeneities (Fath et al, 2019), fast charge (Tanim et al, 2018), hysteresis (Dubarry et al, 2008), overdischarge (Zhang et al, 2022), and many other aspects.…”

Reactivity at the Electrode–Electrolyte Interfaces in Li-Ion and Gel Electrolyte Lithium Batteries for LiNi0.6Mn0.2Co0.2O2 with Different Particle Sizes

“…One of the main problems in the first strategy remains the safety issues, reinforced when combining organic liquid electrolytes with high-voltage positive electrode materials. Indeed, their instability in the charge state of the battery or at high cycling rates can lead to oxygen gas and heat release, to thermal runaway with electrolyte decomposition and flammability, and possibly to fire of the battery. − One of the main concerns in developing even higher-energy LiBs thus remains the optimization of organic electrolytes with appropriate additives to stabilize the electrode–electrolyte interfaces when cycled at a high potential and/or at a high rate. − The additional motivation beyond the higher energy density for the development of ASSBs is that, as free of organic solvents, they appeared as another effective way to address the safety issues. However, the performances of those systems remain poor, and they face a series of challenges to be solved before their development and eventual introduction into the market: mainly, interfacial irreversible reactivity ,− and strong mechanical strains − leading to poor Li + -ion diffusion at the solid–solid electrode–electrolyte interfaces and to the formation of cracks, Li dendrites ,− until possible short-circuits, and safety concerns.…”

An electrochemical evaluation of state-of-the-art non-flammable liquid electrolytes for high-voltage lithium-ion batteries

“…The lattice oxygen atoms of NMC in particular are known to participate in the oxidation of solvent molecules, lowering the effective electrochemical stability limit considerably [48]. For instance, even though EC-based electrolytes often show little oxidative current against inert electrodes [49,50], when electrodes containing active materials are used, EC is the component that limits the oxidative stability of traditional electrolytes [51].…”