Interface‐Targeting Individually Functionalized Ionic Additive to Construct Stable Interphase on Selective Electrode Surface for Practical Lithium‐Ion Pouch Cells

Abstract

Individually functionalized cation‐ and anion‐based ionic additives are designed to mitigate the interfacial side reaction occurring on both the positive and negative electrode surfaces. By applying 1‐phenyl‐1H‐imidazole‐3‐ium trifluoromethanesulfonate as a surface‐targeting electrolyte additive, the reciprocal failure from multiple electrolyte addition applications is theoretically prevented. Selective interface modification is performed using ionic additives by the migration of cations and anions to the negative and positive electrode surfaces, respectively. A drastic improvement in cycleability compared with that by a general carbonate electrolyte is achieved because the reinforcement of both the graphite and LiNi0.8Co0.1Mn0.1O2 electrode surface is possible by ionic additives. Moreover, a further improvement in the cycle performance compared with that by the typical solid electrolyte interphase‐forming additives, such as vinylene carbonate and fluoroethylene carbonate, is demonstrated by the ionic additive.

Improvement of the Li metal-electrolyte interfacial stability by cis–trans polar conformer formation in a carbonate electrolyte

“…The O 1s XPS spectrum indicates that the component from the oxidative decomposition of the electrolyte (C–O, CO) is less observed with the conformer electrolyte, and the lattice oxygen peak was found at the top-most surface, which implies the suppression of the anodic decomposition of the electrolyte on the NCM811 surface with the conformer electrolyte. 28 The 60 s etched O 1s XPS spectrum indicates the increase of the lattice oxygen peaks for both samples, and an intense corresponding peak is observed for NCM811 cycled with the conformer electrolyte, implying that a thin surface film was deposited in the conformer electrolyte (Fig. S6†).…”

“…When the Li electrode is cycled with the conventional carbonate, electrolyte-reduced products with C–O and CO bonding develop severely. 15,28 In addition to the SEI components, the intensity of the lithia, which is often found from the native oxide on the Li electrode, is lower. 15 The higher lithia intensity from the native oxide of the Li electrode and the suppression of the SEI formation from the enhanced cathodic stability of the cycled Li electrode with the conformer electrolyte, show thin SEI film deposition.…”

A sacrificial separator facilitating in situ creation of a durable CEI layer and tailoring lithium dendrites for practical lithium metal batteries

“…Numerous attempts, including the utilization of functional additives, protective articial layers, separator modications, and three-dimensional (3D) frameworks, have been made to adapt the surface structure of Li metal anodes. [14][15][16][17] For NCM811, doping the layered structure and controlling the grain boundary of NCM811 as a single-crystal structure have been extensively investigated, with a focus on increasing the structural stability of NCM811 materials. 18,19 Functional electrolyte additives have also attracted attention because they can form an effective cathode-electrolyte interphase (CEI) layer, which delays the electrolyte decomposition.…”

Vulnerable Solid Electrolyte Interphase Deposition in Sodium-Ion Batteries from Insufficient Overpotential Development during Formation

“…Notably, the SEI is typically considered less suitable for ensuring long-term stability in SIBs, compared with LIBs. − One of the least understood characteristics of the SEI in SIB systems is its thermal stability, , which is a significant attribute for electric vehicle applications. In particular, electric vehicle operation corresponds to a high current application charge and discharge, in which the cell is exposed to elevated temperatures, such as during quick charging and discharging of batteries. , Thus, the thermal stability and passivation ability of SEI film significantly influences the aging of the batteries. ,,,− The imperfections in the SEI on the hard carbon electrode in the presence of Na-ion electrolytes lead to the consumption of Na ions in the confined cell volume through the cathodic decomposition of the electrolyte coupled to the self-discharging of the negative electrode during operation. These phenomena may result in inferior cycle performance of SIBs compared with LIBs.…”

“…The thickness of the SEI film deposited on the hard carbon electrodes is investigated with time-of-flight secondary ion mass spectroscopy (ToF-SIMS) mapping before and after formation (Figure d). All images represent the ToF-SIMS fragment distribution maps of F – and CH 3 O – , which are the marker M–F and C–O bonds. ,, A thick and distinguishable SEI film is clearly observed in the LIB system on hard carbon electrode, compared to the SIB system. This behavior can be attributed to the relatively lower electrode potential and LUMO level of the electrolyte in LIBs, which leads to the formation of a vulnerable SEI on the surface of hard carbon from the decreased solvent reduction kinetics.…”