Lithium Metal Batteries Enabled by Synergetic Additives in Commercial Carbonate Electrolytes

Abstract

The lithium metal anode is considered as the ultimate choice for high-energy-density batteries. However, the organic-dominated solid electrolyte interphase (SEI) formed in carbonate electrolytes has a low interface energy against metallic Li as well as a high resistance, resulting in a low Li plating/stripping Coulombic efficiency (CE) of less than 99.0% and severe Li dendrite growth. Herein, inorganic-enhanced LiF-Li3N SEI is designed in commercial 1 M LiPF6/EC-DMC electrolytes by introducing lithium nitrate (LiNO3) and fluoroethylene carbonate (FEC) through a small amount of sulfolane (SL) as a carrier solvent owing to the high solubility of SL for both carbonate solvents and LiNO3. The comprehensive characterizations and simulations demonstrate that the synergistic interaction of LiNO3 and FEC additives alters the solvation structure of 1 M LiPF6/EC-DMC electrolytes and forms additive-derived LiF-Li3N SEI, which increases the average Li CE up to 99.6% in 100 cycles. The designed carbonate electrolyte enables the Li/LiNi0.80Co0.15Al0.05O2 (NCA) cell with a lean lithium metal anode (∼50 μm) to achieve an average CE of 99.7% and a high capacity retention of 90.8% after 150 cycles. This work offers a simple and economical strategy to realize high-performance lithium metal batteries in commercial carbonate electrolytes.

Insights on “nitrate salt” in lithium anode for stabilized solid electrolyte interphase

“…FEC electrolyte additive can stabilize the SEI of Li metal through the formation of inorganic LiF with high interface energy in the SEI layer, which is similar to nitrates 14,16 . Interestingly, introducing FEC as a solubilizer can enhance the solubility of nitrates in the carbonate electrolyte, and LiF, Li 3 N, and LiN x O y in the SEI have a synergistic effect in stabilizing Li metal anode 39,40 . Therefore, with 5 wt% FEC addition in the electrolyte (Figure ), LKNO||Cu cells showed an even higher average CE of 97.9%, in contrast to 91.8% for Li||Cu cells.…”

“…14,16 Interestingly, introducing FEC as a solubilizer can enhance the solubility of nitrates in the carbonate electrolyte, and LiF, Li 3 N, and LiN x O y in the SEI have a synergistic effect in stabilizing Li metal anode. 39,40 Therefore, with 5 wt% FEC addition in the electrolyte (Figure S14), LKNO||Cu cells showed an even higher average CE of 97.9%, in contrast to 91.8% for Li||Cu cells. The above results further verify the advanced "salt-in-metal" composite anode design utilizing the sustained release of nitrate into the electrolyte for stable cycling.…”

Mapping Techniques for the Design of Lithium‐Sulfur Batteries

“…For the electrolyte, LiNO 3 is the most widely used additive in Li-S battery because its excellent efficiency for the stabilization of SEI. [18][19][20] Besides, other materials have also been used as electrolyte additives to regulate the ion distribution and deposition, which suppress the formation of lithium dendrite. [21][22][23] For the artificial SEI, efforts are focused on the enhanced chemical stability and mechanical robustness, which ensure the integrity of SEI during repeated cycling.…”

Controlled Lithium Deposition

“…The electrolyte additives such as fluorinated ethylene carbonate (FEC) (Zhang X.-Q. et al, 2017;Hou et al, 2019;Lin and Zhao, 2020), LiNO 3 (Zhang et al, 2021a;May et al, 2021;Piao et al, 2021;Wahyudi et al, 2021) and vinylene carbonate (VC) (Kuwata et al, 2016; are beneficial for forming stable SEI layers and inhibiting the growth of the lithium dendrites. The application of the gel electrolytes with high conductivity or solid electrolytes with high mechanical strength to replace the conventional liquid electrolytes also reached great achievements in improving the cycling stability.…”