Li/Li ) and reinforce the design of intrinsically stable electrolytes or suitable electrolyte additives to enable high-voltage lithium-ion batteries.$\ce$), making it a promising positive electrode material for high energy density lithium-ion batteries. The high-voltage cathode materials are highly restricted by the narrow electrochemical stability window state-of-the-art carbonate-based electrolytes (≈1.0 – 4.4 V vs. The product of the specific capacity and the mean discharge voltage gives the specific energy and this relation finds expression in equation 1:Īccording to equation 1, it appears reasonable that most of the current research focuses on new positive electrode materials with higher operation voltages (high-voltage approach) and/or increased specific capacity (high-capacity approach). The energy density and specific energy of batteries by definition is the amount of energy stored in a given system per unit volume and per unit mass, respectively. Especially the increasing demands for both high specific energy and energy density lithium-ion batteries particularly for automotive applications, raise the research efforts all over the world. Our investigations focused on two electrochemical properties, the potential and kinetics of electrolyte oxidation, studied using hard. In order to optimize lithium-ion batteries with respect to the specific energy and energy density, lifetime and safety, many efforts have been made to further expand the application possibilities of LIBs. Herein, we investigate the formation of a cathode electrolyte interphase (CEI) by electrolyte oxidation on a LiNixM1xO2 (x > 0.5 M, transition metal) layered oxide (Ni-rich) cathode and compare this phenomenon with a Li-rich layered oxide (Li-rich) cathode. After the formation of the SEI and CEI, further Li -ions de-intercalate from the positive electrode material into the electrolyte and migrate through it to the negative electrode material to be subsequently incorporated into the latter. These interphases are built up from insoluble electrochemically induced decomposition products of electrolyte components and Li -ions originating from the positive electrode and enable a reversible cycling of the battery. In addition, increasing the charge cut-off voltage of LiCoO2 and NMC battery systems is a simple and effective approach to increase the energy density. As a result of these reactions, boundary phases, the so-called SEI and CEI, are formed at the interfaces between electrolyte / negative electrode surface and electrolyte / positive electrode surface, respectively. To ensure charge neutrality, Li -ions de-intercalate from the positive electrode material into the electrolyte and migrate through the electrolyte to the negative electrode material for subsequent storage. In the very beginning of the first charging process, electrons migrate from the positive electrode material (oxidation) via an external conductor into the negative electrode material (reduction). are protective against further electrolyte decompositionĬontribute to cell safety – being inert to other materials, such as:.Support of the formation of effective interphases (e.g., solid electrolyte interphase, SEI or cathode electrolyte interphase, CEI) which: ![]() The electrolyte in this system contains additional Li -ions to ensure rapid transport of the ionic charge within the cell.īesides ion conduction, the electrolyte fulfills other important purposes: The term discharge is used for the process in which the battery supplies electrical energy to an external load. ![]() In conventional lithium-ion batteries, Li -ions are shuttled between the positive electrode (usually a layered transition metal oxide material) and a graphite-based negative electrode according to the “rocking chair” principle (cf. Lithium-ion batteries can be further divided into primary (non-rechargeable) and secondary (rechargeable) batteries, depending on whether or not they are rechargeable by applying an electric current. the negative (anode) and a positive electrode (cathode), in one or more electrically connected electrochemical cells. Lithium-ion batteries belong to the group of batteries that generate electrical energy by converting chemical energy via redox reactions on the active materials, i.e.
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