Competitive Solvation Structure in a Deep Eutectic Electrolyte Enables High‐Voltage LiCoO 2 ‐Based Pouch Cells With 5000‐Cycle Stability

Anion‐rich solvation structures improve interfacial stability but often impede Li + desolvation, limiting fast‐charging and low‐temperature performance in high‐voltage lithium metal batteries. Unlike conventional high‐concentration or weakly solvating electrolytes, we propose a deep eutectic electrolyte (DEE) using succinonitrile (SN) and dimethyl sulfone (MSM) with competitive coordination capability. This design shifts the Li + solvation from aggregate clusters (AGGs) to a balanced AGGs/contact ion pairs (CIPs) distribution, which lowers the Li + desolvation energy barrier, enhances the transport kinetics, and endows the DEE with an ionic conductivity of 3.87 mS cm −1 and a Li + transference number of 0.81. MSM moderates excessive SN coordination, suppressing parasitic reactions on the anode, thereby enabling stable Li plating/stripping for 6800 h. A lithium bis(trifluoromethanesulfonyl)imide (LiTFSI)/lithium difluoro(oxalato)borate (LiDFOB) dual‐salt system further optimizes interfacial chemistry, yielding a bilayer solid electrolyte interphase comprising an inorganic‐rich inner layer and a flexible organic outer layer. LiCoO 2 ||Li cells retain 97.1% capacity after 1000 cycles at 5C (3.0–4.5 V) and operate stably at −10°C. A 3.0 Ah LiCoO 2 ||Li pouch cell further delivers a high energy density of 417 Wh kg −1 , and LiCoO 2 ||graphite pouch cells sustain long‐term durability over 5000 cycles. This competitive solvation strategy effectively harmonizes kinetics and interfacial robustness for high‐voltage, fast‐charging DEEs.