Effect of Fluoroethylene Carbonate in the Electrolyte for LiNi_0.5Mn_1.5O₄ Cathode in Lithium-ion Batteries

Abstract

Fluoroethylene carbonate (FEC) was studied as an additive for the electrolyte in lithium ion batteries with the LiNi(LNMO) spinel cathode operating at a high potential beyond 4.7 V (vs. Li/Li + ). It was found that the FEC additive was electrochemically active for the 1 s t charge cycle on the LNMO cathode. The presence of a large amount of FEC (more than 40 vol%) in the electrolyte caused severe side reactions with abnormally long voltage plateaus. In contrast, when the electrolyte contained less than 30 vol% FEC , the surface of the LNMO cathode was stabilized by the formation of the solid-electrolyte interphase (SEI), leading to improved cyclability. However, the resistance from the SEI limited the rate capability because of sluggish lithium transportation through the SEI and electronic insulation between the particles in the electrode.

Modification of suitable electrolytes for high-voltage lithium-rich manganese-based cathode with wide-temperature range

“…The new organic solvents are mainly uorinated substitutes, sulfones and nitrile. Due to the extremely small dimensions of uorine atom and the large repulsive force of the nucleus, its electronegativity and weak polarity make the uorinated compounds have good oxidation resistance [18][19][20], so the uorinated solvent uorinated ethylene carbonate (FEC) is used in this paper [21].…”

“…The introduction of uorine atoms can signi cantly increase the electron-absorbing capacity of the solvent, so that uorinated solvent exhibits high oxidation stability [31]. Lithium di uorooxalate borate (LiDFOB) [21] has the characteristics of high solubility, electrical conductivity, good lm formation, etc.…”

Study on annealing treatment of spinel LiNi 0 . 5 Mn 1 . 5 O 4 as cathode materials for high‐voltage lithium‐ion batteries

“…These transition metal ions will be reduced to metallic compounds after diffusing to the surface of the negative electrode, destroying the solid electrolyte interphase (SEI) film components of the negative electrode, and the continuous repair of SEI film will lead to the irreversible attenuation of battery capacity. [55][56][57] On the other hand, HF corrodes the active substance in the positive electrode, making the CEI film on the surface of the material thicker and thicker with circulation, resulting in severe polarization. According to reports, the morphologic modification of the material can effectively restrain the degradation behavior.…”

Electrochemical Analysis for Enhancing Interface Layer of Spinel LiNi0.5Mn1.5O4 Using p-Toluenesulfonyl Isocyanate as Electrolyte Additive

“…One way is to make electrolyte additives form a stable SEI film on the cathode, which inhibits LNMO electrode interface erosion and electrolyte decomposition, scavenging type to capture HF (Haregewoin et al, 2016; Wang et al, in press). As the strong acid produced from LiPF 6 is considered the initiator which induces the cleavage and polymerization of cyclic carbonate under high voltage conditions, many researchers are trying to add some oxidation-resistant solvents, for example, sulfones (Hilbig et al, 2017; Su et al, 2017), nitriles (Abu-Lebdeh and Davidson, 2009) and fluoro solvents (Kim et al, 2017). However, when adding the oxidation-resistant solvents there are new problems, including a decrease of conductivity, an increase of viscosity and poor compatibility.…”