A Superior Carbonate Electrolyte for Stable Cycling Li Metal Batteries Using High Ni Cathode

Abstract

Li metal batteries pairing Li metal anode with high-nickel layer structured oxide cathode are a promising energy storage technology to achieve high energy density. To obtain long cycling life for Li metal batteries, the electrolyte plays a pivotal role in stabilizing both the Li metal anode and the high-nickel cathode upon electrochemical cycling. Herein, we report a carbonate electrolyte that enables a Li∥Li-Ni 0.8 Mn 0.1 Co 0.1 O 2 pouch cell to achieve a high gravimetric energy density of 366 Wh/kg and unprecedented cycling stability with 80% capacity retention after 335 cycles. The 19 F quantitative nuclear magnetic resonance spectroscopy and interface characterization demonstrate that FEC and LiDFOB can reduce the consumption rate of each other and the electrolyte, form a robust LiF-rich SEI on Li metal anode, and improve the microstructure integrity of the high-nickel cathode.

A Review on Regulating Li+Solvation Structures in Carbonate Electrolytes for Lithium Metal Batteries

“…Due to their improved sustainability, the Li||Cu and NCM811||Li cells exhibited much more stable cycling compared to the baseline electrolyte and that only with FEC (Figure 8g), confirming the combined effect of FEC and LiDFOB. [60] The introduction of additives to the solvation structure dominated by salt anions also delivers a combined effect. Zhang's group used BTFE as the diluent to obtain a LHCE and the cycling performance of the Li||Cu cells and Li||Li cells was significantly improved with long cycling life, low polarization voltage, and high Coulombic efficiency (Figure 8h), indicating the effectiveness of the solvation structure dominated by salt anions.…”

“…[47] However, their low solubility has hindered their use as the main salts of carbonate electrolytes and LiDFOB is more used as an additive. [34,[59][60][61] Lithium bis(trifluoromethanesulfonyl) imide (LiTFSI) and lithium bis(fluorosulfonyl)imide (LiFSI) are alternative Li salts in carbonate electrolytes, but they corrode the current collector of the cathode aluminum (Al) at high voltages, restricting their use in dilute carbonate electrolytes. [62] Fortunately, it is avoided in HCEs and LHCEs without free solvents dissolving Al 3+ , [63] thus along with the desirable solubility and film-forming capability of LiTFSI and LiFSI, they have been extensively investigated in HCEs and LHCEs.…”

A functional electrolyte additive enabling robust interphases in high-voltage Li‖LiNi0.8Co0.1Mn0.1O2 batteries at elevated temperatures

“…Interestingly, the atomic content of F in the PS electrolyte remains unchanged, and the signal of S was detected, indicating the involvement of PS in the formation of the SEI and the inhibition of LiPF 6 hydrolysis. The F 1s spectra of the SEI in the blank electrolyte can be identified as two peaks, corresponding to LiF (684.9 eV) and Li x PO y F z (686.8 eV), 47 as shown in Fig. 3f.…”

Interlayer Modulation of Layered Transition Metal Compounds for Energy Storage

“…Irreversible phase transition in the layered structure upon (de)­intercalation of carrier ions also destroys the layered structure and blocks the Li-ion fast-diffusion channels, leading to short cycling life and sluggish reaction kinetics . For some layered transition metal oxides such as LiNi 0.8 Mn 0.1 Co 0.1 O 2 , the extensive extraction of oxygen and carrier ions at the high charge voltage plateau will cause lattice breakdown and irreversible layer-to-spinel phase transformation.…”