3,3‐Diethylene Di‐Sulfite (DES) as a High‐Voltage Electrolyte Additive for 4.5 V LiNi_0.8Co_0.1Mn_0.1O₂/Graphite Batteries with Enhanced Performances

Abstract

A functional electrolyte containing 3,3‐diethylene di‐sulfite (DES) additive is developed to improve the performances of LiNi0.8Co0.1Mn0.1O2 (NCM811)/graphite batteries, especially at high charging cut‐off voltage of 4.50 V. It is indicated that under the conventional conditions of 25 °C and 1 C after 300 cycles in the voltage range of 2.75–4.30 V, the batteries with 0.25 % DES can increase the maximum capacity retention from 66.61 % to 77.25 % initial discharge capacity compared with the batteries without DES. Especially, when the charge cut‐off voltage is increased to 4.50 V, the batteries with 1 % DES exhibit higher capacity retention (82.53 %) after 150 cycles than the batteries without DES (51.19 %). The electrochemical tests and spectroscopic characterization show that this functional DES electrolyte additive well regulates the anode and cathode interfaces with more stabilized films and smaller impedance, which promotes the interfacial extraction and insertion of Li+. In addition, the interfacial film can inhibit the dissolution of the transition metal element Ni from the cathode and protect the structure stability of NCM811 material. The electrolyte containing DES additive reveals promising prospects in the application of NCM811/graphite batteries.

Isocyanoethyl Methacrylate (IMA) as a Bifunctional Electrolyte Additive for LiNi0.8Co0.1Mn0.1O2/Graphite Batteries with Enhanced Performance

“…Two approximate semicircles were observed in the EIS spectra after activation and cycling. The semicircle diameter in the high frequency region usually represents the interface impedance (Rsei), and the semicircle diameter in the medium frequency region usually reflects the electrochemical reaction impedance (Rct) [9,30–34] . In the ultra‐high frequency (UHF) part, the focus of impedance spectrum and coordinate axis is ohmic impedance (Rs).…”

“…It is observed that a pair of strong peaks at about −75 ppm belong to PF 6 − in lithium salt LiPF 6 . A pair of peaks at about −85 ppm can be attributed to PO 2 F 2 − , which is one of the decomposition products of the reaction between LiPF 6 and H 2 O, while the other product HF, which has a negative effect on the cycle performance of the battery, is located at approximately −190 ppm [9] . The peak intensity of PO 2 F 2 − at about −85 ppm in the electrolyte containing IMA additive is lower than that in the blank electrolyte, which indicates that IMA can inhibit the reaction between LiPF 6 and H 2 O, thus reducing the production of HF.…”

“…It is an effective way to develop the high specific capacity and high voltage cathode materials to increase the specific energy of LIBs [5] . Among them, the high‐nickel ternary layered oxides LiNi x Co y Mn z O 2 (NCM, 0.5<x, x+y+z=1) have attracted wide attention due to their high specific capacity [6–9] . However, the high‐nickel NCM cathodes have the technical problem to be solved in the existing commercial electrolyte system due to their strong oxidizing ability and poor structural stability [10–12] .…”

Propanediol Cyclic Sulfate as An Electrolyte Additive to Improve the Cyclic Performance of LiNi0.6Co0.1Mn0.3O2/Graphite Pouch‐Cell at High Voltage

“…XPS is presented in Figure 5, the peaks at 284.7, 286.1, 288.8 and 290.0 eV belong to CÀ C, CÀ O, C=O and CÀ F bonds in the C 1s spectra, respectively. [25] The CÀ O and C=O bonds can be attributed to carbonate solvent decomposition, and the formation of CÀ C and CÀ F bonds is related to super P and PVDF (polyvinylidene fluoride). [32] Comparison of the C 1s spectra of the baseline and the electrolyte with PCS shows that the strength of CÀ O and C=O bonds is reduced after the addition of PCS.…”

“…[18][19][20][21] With the increase of research on electrolyte additives, it has been found that additives containing S=O bonds often have surprising effects. [22][23][24][25][26] Huang et al [27] reported that after adding methyl phenyl sulfone (MPS) to the base electrolyte, the CEI formation on the surface of LNMO (LiNi 0.5 Mn 1.5 O 4 ) had a higher ionic-conductivity than that in the baseline electrolyte, thus improving the cycle and rate capability of LNMO/Li cells at 4.9 V cut-off voltage. Lu et al [28] demonstrated that phenyl 4fluorobenzene sulfonate (PFBS) can improve the cycling stability of LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM811)/graphite pouch-cell at 45 °C, because the S-containing SEI/CEI produced by PFBS improves the thermal stabilization of the electrode/electrolyte interface.…”