Insight into the Improved Performances of Ni-Rich/Graphite Cells by 1,3,5-Trimethyl-1,3,5-tris(3,3,3-trifluoropropyl) Cyclotrisiloxane as an Electrolyte Additive

Abstract

A Ni-rich cathode is one of the representatives for lithium-ion batteries that can deliver a higher energy density with lower cost than any other counterparts, but its cyclic stability is unsatisfactory. 1,3,5-Trimethyl-1,3,5-tris­(3,3,3-trifluoropropyl) cyclotrisiloxane (D3F) as an electrolyte additive is effective for performance improvement of the Ni-rich cathode. Evaluated in a cell based on the Ni-rich cathode (LiNi0.8Co0.1Mn0.1O2, NCM811) and a graphite anode in 1 M LiPF6-EMC/EC/DEC (3/5/2 in weight) between 3.0 and 4.35 V, the application of 5% D3F without any co-contribution of other electrolyte additives enhances the capacity retention of the cell from 38 to 76% after 300 cycles at 1C. The underlying mechanism is understood by combining theoretical calculation with physical characterization and electrochemical measurements. D3F can be electrochemically oxidized and reduced preferentially compared to the electrolyte components, creating robust interphases simultaneously on the cathode and anode. Additionally, it can scavenge HF and eliminates its detrimental effect on battery performances. This understanding helps to further enhance the performance of Ni-rich/graphite cells via designing electrolyte additives.

Borate-Functionalized Disiloxane as Effective Electrolyte Additive for 4.5 V LiNi0.8Co0.1Mn0.1O2/Graphite Batteries

“…The oxygen-free radical L is obtained through the oxidation of complex A . Free radical L should act as an initiator for the polymerization of the electrolyte solvents and eventually can be terminated by EMC or DMC to give oligomer M , , and forms CEI-film.…”

Stable and Fast Ion Transport Electrolyte Interfaces Modified with Novel Fluorine- and Nitrogen-Containing Solvents for Ni-Rich Cathode Materials

“…The rightward shift of the (101) peak and the leftward shift of the (018) peak in the STD indicate that the lattice constant a decreases, which is associated with the structural transition from the layered phase to the spinel phase or even the rock salt phase. 28,49,55 With the MNTB/FEC electrolyte, the NCM811 cathode exhibits improved cyclic stability due to its better structural stability after 200 cycles, as shown in Figure 2a.…”

Optimized Solid Electrolyte Interphase and Solvation Structure of Potassium Ions in Carbonate Electrolytes for High‐Performance Potassium Metal Batteries

“…As shown in Figure a, the LUMO energy level of ATPPB (−0.95 eV) is lower than that of EC (0.94 eV) and DEC (1.26 eV), which indicates that ATPPB has a tendency to be preferentially reduced over EC and DEC on the K metal anode during the reaction process. [ 23 ] Besides, the energy gap of ATPPB, EC, DEC and KPF 6 is calculated as 3.76, 8.94, 8.87, and 7.36 eV, respectively. According to previous articles, [ 24 ] the wider the gap, the more stable the molecule.…”