Multifunctional solvent molecule design enables high-voltage Li-ion batteries

Abstract

Elevating the charging cut-off voltage is one of the efficient approaches to boost the energy density of Li-ion batteries (LIBs). However, this method is limited by the occurrence of severe parasitic reactions at the electrolyte/electrode interfaces. Herein, to address this issue, we design a non-flammable fluorinated sulfonate electrolyte by multifunctional solvent molecule design, which enables the formation of an inorganic-rich cathode electrolyte interphase (CEI) on high-voltage cathodes and a hybrid organic/inorganic solid electrolyte interphase (SEI) on the graphite anode. The electrolyte, consisting of 1.9 M LiFSI in a 1:2 v/v mixture of 2,2,2-trifluoroethyl trifluoromethanesulfonate and 2,2,2-trifluoroethyl methanesulfonate, endows 4.55 V-charged graphite||LiCoO2 and 4.6 V-charged graphite||NCM811 batteries with capacity retentions of 89% over 5329 cycles and 85% over 2002 cycles, respectively, thus resulting in energy density increases of 33% and 16% compared to those charged to 4.3 V. This work demonstrates a practical strategy for upgrading the commercial LIBs.

Nonfluorinated Antisolvents for Ultrastable Potassium-Ion Batteries

“…There is a considerable difference in C elemental contents, which is attributed to the difference in SEI thickness. This is because the etching beam easily penetrates the thin SEI, leading to an enhanced effect of the C elemental content in bulk graphite on the overall elemental composition analysis . Furthermore, the O elemental content of the graphite electrode surface provides valid evidence of the molecular decomposition of the solvent and represents the proportion of organic components inside the SEI .…”

“…This is because the etching beam easily penetrates the thin SEI, leading to an enhanced effect of the C elemental content in bulk graphite on the overall elemental composition analysis. 7 Furthermore, the O elemental content of the graphite electrode surface provides valid evidence of the molecular decomposition of the solvent and represents the proportion of organic components inside the SEI. 12 The elemental content of the KFSI/TMP−DX electrolyte is considerably lower than that in KFSI/TMP and KFSI/TMP−DME electrolytes, and the difference in their relative ratios indicates that the SEI formed by graphite electrodes in KFSI/TMP and KFSI/TMP−DME electrolytes holds organically rich components, which may be the main reason behind the poor cycling stability of graphite anodes (Figure 5h−j and Figure S31).…”

“…Rechargeable potassium-ion batteries (PIBs) offer exciting advantages, such as abundant potassium resources and high operating voltage, and therefore hold great promise for development. − The electrolyte is an indispensable component of a battery that guarantees its efficient cycling. − The solvent and anion coordinate and interact with the cation in the electrolyte competitive ion–dipole or ion–ion interactions. , In typical solvent-derived interfacial chemistry, the component coordinating with the cation (cation inner solvation sheath) preferentially decomposes and forms a solid–electrolyte interphase (SEI) at the anode surface. − The anion-derived, inorganic-rich SEI is an effective guarantee for stable battery operation. − Accordingly, by improving the structure of the inner solvation sheath and enhancing the interaction between anions and cations, the formation of anion-derived, inorganic-rich SEI is facilitated. , In this manner, by shifting the equilibrium of the original electrolyte and improving the interaction between anions and cations, the electrochemical performance of the battery can be enhanced.…”

A Bio-Based Molecule to Afford a Lithium-Metal Battery by Modification with the Electrode–Electrolyte Interphase

“…The poor solid electrolyte interphase (SEI) in the anode may cause the growth of Li dendrite, leading to short-circuiting of the batteries. 11 In addition, the poor cathode electrolyte interphase (CEI) causes particle breakage and irreversible phase change, resulting in capacity loss. 12 Therefore, to produce high-energy-density LMBs, it is necessary to stabilize the anode and cathode by regulating the SEI and CEI.…”

“…Due to the obvious high specific capacity (3860 mAh g –1 ) and low reduction potential (−3.04 V) of the lithium (Li)-metal anode, Li-metal batteries (LMBs) have seen a resurgence due to the rising demand for electronics and hybrid electric vehicles. − Furthermore, Li/LiNi 0.8 Co 0.1 Mn 0.1 O 2 (Li/NCM811) cells are a good contender for next-generation advanced batteries due to the high specific capacity of the NCM811 cathode. − Despite this, the performance of Li/NCM811 batteries is still much below its theoretical expectation due to a significant side reaction between the electrolyte and electrode. , Especially, the instability of the interphase between the electrode and electrolyte leads to electrode degradation. The poor solid electrolyte interphase (SEI) in the anode may cause the growth of Li dendrite, leading to short-circuiting of the batteries . In addition, the poor cathode electrolyte interphase (CEI) causes particle breakage and irreversible phase change, resulting in capacity loss .…”