Regulating the Solvation Sheath of Li Ions by Using Hydrogen Bonds for Highly Stable Lithium–Metal Anodes

Abstract

The performance of Li anodes is extremely affected by the solvation of Li ions, leading to preferential reduction of the solvation sheath and subsequent formation of fragile solid–electrolyte interphase (SEI), Li dendrites, and low coulombic efficiency (CE). Herein, we propose a novel strategy to regulate the solvation sheath, through the introduction of intermolecular hydrogen bonds with both the anions of Li salt and the solvent by small amount additives. The addition of such hydrogen bonds reduced the LUMO energy level of anions in electrolyte, promoted the formation of a robust SEI, reduced the amount of free solvent molecules, and enhanced stability of electrolytes. Based on this strategy, flat and dense lithium deposition was obtained. Even under lean electrolytes, at a current density of 1 mA cm−2 with a fixed capacity of 3 mAh cm−2, the Li–Cu cells showed an impressive CE value of 99.2 %. The Li‐LiFePO4 full cells showed long‐term cycling stability for more than 1000 cycles at 1 C, with a total capacity loss of only 15 mAh g−1.

Electrode–Electrolyte Interfacial Chemistry Modulation for Ultra‐High Rate Sodium‐Ion Batteries

“…It is also concluded that Na + is more easily solvated by the cyclic carbonate ester solvents to form a solvation-Na + complex compared with the linear carbonate ester solvents and the combination of THF and Na + shows a weakly solvated structure. [15] Hence, the binding energies provided for Na + (THF) 3.3 , Na + (DME) 2.4 , Na + (DEC/EC) 1.5 and Na + (PC) 1.4 complexes can be regarded as a qualitative indication of their divergent desolvation barriers. The more positive solvation binding energy between Na + and THF indicates a lower desolvation energy of Na + (THF) 3.3 , that is, the energy barrier for Na + to desolvate on the electrode surface is lower, which accelerates the transport kinetics of Na + .…”

Phenoxy Radical‐Induced Formation of Dual‐Layered Protection Film for High‐Rate and Dendrite‐Free Lithium‐Metal Anodes

“…[20] The-OH group interacts strongly with -CF 3 from LiTFSI through the hydrogen bonding (O-H-F) and promotes the decomposition of LiTFSI to form LiF. [21] As aproof of concept, aprotection film with dual-layered structure is spontaneously constructed on surface of Li anode via two-step chemical reactions between Spiro-O8 and Li and electrolyte,r espectively.A ss hown in Figure 3a,S piro-O8 with phenoxy radicals will readily acquire electrons from the highly reactive Li metal and forms an organic Spiro-O8-Li film with remaining phenoxy radicals on top surface.W hen the Spiro-O8-Li@Li anode contact the electrolyte in the battery assemble process,the phenoxy radicals on top surface can acquire hydrogen atoms from DME molecule and result in the formation of hydroxyl groups,w hich will induce the decomposition of LiTFSI to form inorganic LiF film. However,S piro-OMeTAD coating layer cannot successfully construct adual-layered protective layer due to its high chemical…”

Lithium reduction reaction for interfacial regulation of lithium metal anode

“…According to recent experimental and theoretical works, additives usually have a lower LUMO than solvents. 94 They can firstly be reduced by LMA and participate in the formation of high-quality SEI films, thus significantly reducing electrolyte consumption.…”