Synergistic Dual‐Additive Electrolyte Enables Practical Lithium‐Metal Batteries

Abstract

A rechargeable Li metal anode coupled with a high‐voltage cathode is a promising approach to high‐energy‐density batteries exceeding 300 Wh kg−1. Reported here is an advanced dual‐additive electrolyte containing a unique solvation structure and it comprises a tris(pentafluorophenyl)borane additive and LiNO3 in a carbonate‐based electrolyte. This system generates a robust outer Li2O solid electrolyte interface and F‐ and B‐containing conformal cathode electrolyte interphase. The resulting stable ion transport kinetics enables excellent cycling of Li/LiNi0.8Mn0.1Co0.1O2 for 140 cycles with 80 % capacity retention under highly challenging conditions (≈295.1 Wh kg−1 at cell‐level). The electrolyte also exhibits high cycling stability for a 4.6 V LiCoO2 (160 cycles with 89.8 % capacity retention) cathode and 4.95 V LiNi0.5Mn1.5O4 cathode.

Gradient Solid Electrolyte Interphase and Lithium‐Ion Solvation Regulated by Bisfluoroacetamide for Stable Lithium Metal Batteries

“…The chemical compositions of CEI formed in LiPF 6 ‐EC/DMC and LiPF 6 ‐EC/DMC‐BFA electrolyte were analyzed using XPS. In O1s spectra (Figures 5 i), the M‐O (528.1 eV) peak is not detected in the CEI with BFA additive, which is related to the NiO or CoO decomposition products [52] . In C1s spectra (Figures 5 j), the signals of C−C (283 eV), C‐O (284.6 eV), CO 3 2− (287.1 eV) can be clearly detected.…”

An Inorganic‐Rich Solid Electrolyte Interphase for Advanced Lithium‐Metal Batteries in Carbonate Electrolytes

“…One method is to maintain LiNO 3 in carbonate solvents by implanting LiNO 3 particles into porous PVDF‐HFP [31] or glass fiber [35] as separators or coating layers on Li metal anode surfaces, which will be continuously dissolved into the electrolyte when the trace amount of dissolved LiNO 3 in the electrolyte is consumed. Another method is to add LiNO 3 solubilizers such as copper fluoride, [36] γ‐butyrolactone, [37] and Tin trifluoromethanesulfonate, [38] tris(pentafluorophenyl)borane [39] into carbonate electrolytes to improve the solubility of LiNO 3 . However, these LiNO 3 solubilizer additives also destabilize the SEI, as evidenced by a lower Li plating/stripping CE of <99 % than that (99.3 %) [40] of highly concentrated or all‐fluorinated LiFSI (or LiPF 6 ) single‐salt carbonate electrolytes [41] .…”

Regulating Mass Transport Behavior for High‐Performance Lithium Metal Batteries and Fast‐Charging Lithium‐Ion Batteries

“…To date, numerous additives have been developed for the construction of stable SEI layers with high Li‐ion conductivity to improve both Li metal batteries and fast‐charging Li‐ion batteries. [ 7,25,112–120 ] However, additives in the electrolyte may negatively affect the viscosity and Li‐ion conductivity of the electrolyte; moreover, the limited amount of the additives will be quickly consumed out, leading to a lack of long‐term protection of the anodes. Fabrication of artificial SEI layers on the anodes is an alternative to promote the Li‐ion transport through the SEI.…”