The development of high-energy-density and high-safety lithium-ion batteries requires advancements in electrolytes. The state-of-the-art carbonate electrolyte faces challenges for operation at high voltage and has low thermal stability. This study proposes an ionic liquid/ether composite high-entropy electrolyte that consists of N-propyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide (PMP–TFSI) ionic liquid, dimethoxymethane (DME), lithium difluoro(oxalato)borate (LiDFOB), fluoroethylene carbonate (FEC), and 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether (TTE). In this electrolyte, a unique coordination structure forms, where Li+ is surrounded in a high-entropy environment consisting of DME, FEC, TTE, TFSI–, DFOB–, and PMP+. The effects of this solution structure on the solid-electrolyte interphase chemistry and Li+ desolvation kinetics are examined. The proposed electrolyte has low flammability, high thermal stability, negligible corrosivity toward an Al current collector, and ability to withstand a high potential of up to 5 V without showing a significant side reaction current. Importantly, this electrolyte is highly compatible with graphite and SiOx anodes, as well as a high-nickel LiNi0.8Co0.1Mn0.1O2 cathode. Operando X-ray diffraction data confirm that the co-intercalation of DME and PMP+ into the graphite lattice, a long-standing challenge, is eliminated with this electrolyte. Graphite, SiOx, and LiNi0.8Co0.1Mn0.1O2 electrodes all exhibit better rate capability and cycling stability in the proposed electrolyte compared to those measured in a conventional carbonate electrolyte. A 4.5-V LiNi0.8Co0.1Mn0.1O2//graphite full cell with the proposed high-entropy electrolyte is shown to have superior specific capacity, rate capability, and cycling stability, demonstrating the great potential of the proposed electrolyte for practical applications.
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Li–S Batteries
In article number 2405365, Yu-Sheng Su and co-workers introduce an innovative lithium-sulfur battery configuration featuring a sulfur-coated separator and an interwoven rGO/CNT fabric current collector. By addressing challenges such as sulfur utilization, polysulfide shuttling, and electrode stability, this design achieves superior cycling stability, enhanced capacity retention, and scalability, paving the way for high-performance, sustainable energy storage solutions essential for future technologies.
Small-Molecule Polycyclic Aromatic Hydrocarbons
In article number 2400273, Jeng-Kuei Chang, Elise Yu-Tzu Li, Yu-Sheng Su, and co-workers present geometric variations of pyrene crystals during the electrochemical process in Li-ion batteries. The image illustrates the irreversible structural collapse caused by the vertical expansion of pyrene dimers, leading to the dissolution of pyrene into the electrolyte, a key factor affecting the long-term cycling stability of the anode material.
