Tuning the Li⁺ Solvation Structure by a “Bulky Coordinating” Strategy Enables Nonflammable Electrolyte for Ultrahigh Voltage Lithium Metal Batteries

Abstract

In battery electrolyte design principles, tuning Li+ solvation structure is an effective way to connect electrolyte chemistry with interfacial chemistry. Although recent proposed solvation tuning strategies are able to improve battery cyclability, a comprehensive strategy for electrolyte design remains imperative. Here, we report a solvation tuning strategy by utilizing molecular steric effect to create a “bulky coordinating” structure. Based on this strategy, the designed electrolyte generates an inorganic-rich solid electrolyte interphase (SEI) and cathode–electrolyte interphase (CEI), leading to excellent compatibility with both Li metal anodes and high-voltage cathodes. Under an ultrahigh voltage of 4.6 V, Li/NMC811 full-cells (N/P = 2.0) hold an 84.1% capacity retention over 150 cycles and industrial Li/NMC811 pouch cells realize an energy density of 495 Wh kg–1. This study provides innovative insights into Li+ solvation tuning for electrolyte engineering and offers a promising path toward developing high-energy Li metal batteries.

Unlocking Reversible Silicon Redox for High‐Performing Chlorine Batteries

“…The presence of 60 % DCE slightly shortened the distances of LiÀ O (SOCl 2 ) and LiÀ Al (AlCl 4 À ) and resulted in a new LiÀ C (DCE) peak at 2.9 Å (Figure 4d). This indicated that DCE molecules were involved in the first layer of the solvation structure that encircled the Li ions and SOCl 2 molecules, [37,38] thus serving as an effective diluent that effectively suppressed the corrosivity of the SOCl 2 -based electrolyte (Figure S14).…”

Fatigue-Free and Skin-like Supramolecular Ion-Conductive Elastomeric Interphases for Stable Lithium Metal Batteries

“…One routine way is to promote in situ formation of a stable SEI layer by optimizing the electrolytes, including sacrificial additives, highly concentrated electrolytes, and fluorinated electrolytes . Nevertheless, the so-formed SEI continuously grows by constantly consuming the electrolyte solvents, salt anions, or sacrificial additives in the electrolyte, making it difficult to modulate the composition and structure of the SEI. − Accordingly, the improvement in cycling stability by using a large excess of electrolyte inevitably compromises the energy density of batteries. Another approach is to replace the electrolyte-derived SEI by ex-situ formed artificial SEI layers such as inorganic materials (for example, Li 3 PO 4 , LiF, Li 2 S), organic polymers (for example, polyrotaxane- co -poly­(acrylic acid) (PR–PAA), P­(St-MaI), polydimethylsiloxane, and copolymer of poly­(ethylene glycol) methyl ether methacrylate and 2-[3-(6-methyl-4-oxo-1,4-dihydropyrimidin-2-yl)­ureido]­ethyl methacrylate), and organic–inorganic composites. − However, ionic insulation or poor ionic conductivity would definitely retard the Li + transfer across the interface, resulting in increased polarization and dendrite growth .…”

Tuning and Balancing the Donor Number of Lithium Salts and Solvents for High-Performance Li Metal Anode

“…Although there has been much work focused on optimizing the electrolyte systems, − there are some aspects remaining to be improved. First, the options of the electrolytes are limited, most of which are ester- or ether-based electrolytes with high combustibility.…”