Enhanced performance of the electrolytes based on sulfolane and lithium difluoro(oxalate)borate with enhanced interfacial stability for LiNi0.5Mn1.5O4 cathode

Deciphering the Interface of a High‐Voltage (5 V‐Class) Li‐Ion Battery Containing Additive‐Assisted Sulfolane‐Based Electrolyte

“…This suggests that the TMSP additive derived species are beneficial to form conductive and protective SEI layers on both electrodes (especially MCMB anode). To the best of our knowledge, this is the first attempt to directly evaluate high safety LiDFOB/SL‐based electrolytes in conventional Li‐ion full‐cells with intercalation type cathode and graphite anode.…”

“…The bad thermal stability and high moisture sensitivity of LiPF 6 salt always cause the formation of undesired HF, which will damage LiNi 0.5 Mn 1.5 O 4 cathode by dissolving transitional metals, and in consequent migrates to graphite anode, affecting the SEI layer quality negatively . Conventional electrolytes process poor oxidative stability exceeding 4.5 V versus Li/Li + , leading to the undesired formation/deposition of oxidation byproducts on electrode interfaces . Moreover, the carbonate solvents are highly flammable, while the battery safety risks are rising with the improvement of energy density .…”

“…From the perspective of adopting high thermal stability novel lithium salt, lithium difluoro(oxalate)borate (LiDFOB, Figure a) is regarded as a competitive alternative due to its high thermal decomposition temperature up to 240 °C (HF generation is not easy) . More importantly, LiDFOB can participate in formation of effective SEI layers on both cathode and anode, and has the ability of passivating aluminum cathode current collector at high potentials.…”

“…More importantly, LiDFOB can participate in formation of effective SEI layers on both cathode and anode, and has the ability of passivating aluminum cathode current collector at high potentials. Therefore, LiDFOB has been always studied as a main lithium salt or functional additive to significantly enhance the electrochemical performances of LIBs, especially at elevated temperatures . As for solvent, sulfolane (SL, also tetramethylene sulfone, Figure a) is a potential electrolyte solvent candidate for high‐voltage cathode materials due to its high dielectric constant (ε = 43.4), wide electrochemical stability window (the oxidative stability exceeds 5 V vs Li/Li + ), and less flammability ( T flash point = 165 °C, T boiling point = 287 °C) .…”

“…In summary of the aforementioned background, the combination of LiDFOB and SL will be a promising electrolyte choice for the complicated 5 V‐class LiNi 0.5 Mn 1.5 O 4 /graphite battery. Actually, LiDFOB/SL has been always blended with linear alkyl carbonates, ionic liquid, acyclic sulfones . Despite these LiDFOB/SL‐based novel electrolytes are reported to demonstrate excellent compatibility with varied cathode materials (including LiNi 0.5 Mn 1.5 O 4 ) and graphite anode in half‐cell evaluation, their application in full‐cells are rarely concentrated.…”