Nonafluorobutane‐1‐Sulfonic Acid Induced Local High Concentration Additive Interface for Robust SEI Formation of High‐Voltage (5 V‐Class) Lithium Metal Batteries

Abstract

To optimize anode and cathode degradation issues in high-voltage (5 V-class) lithium metal batteries (LMBs), robust solid-electrolyte interfaces (SEI) on the surface of both anode and cathode are highly desired. Here, a nonafluorobutane-1-sulfonic acid (NFSA) additive is introduced to assist in the formation of the more stable and robust SEI to protect both anode and cathode. Typically, local high concentrations of lithium nonafluorobutane-1-sulfonate (NFSALi) and nonafluorobutane-1-sulfonate anion (NFSA − ) could be achieved at the surface of anode and cathode respectively, through spontaneous chemical processes. The lowest unoccupied molecular orbital energy of NFSALi is lower and the highest occupied molecular orbital (energy of NFSA − is higher than electrolyte solvents. Thus, conformal and dense SEI passivation films are generated on the surface of both anode and cathode derived from electrochemical decomposition of NFSALi and NFSA − , respectively. Consequently, stable operation of Li metal anode and high-voltage cathode are realized. The LiNi 0.5 Mn 1.5 O 4 (LNMO)//Li LMBs with NFSA-containing electrolyte show great cycling stability with 93% capacity retention after 400 cycles and more stable Coulombic efficiency. This work specifies the double functions of NFSA as an interfacial layer forming additive to solve the degradation problems of high-voltage (5 V-class) LMBs, enabling high-energy LMBs with significantly improved battery performance.

Diethyl (4-isopropylbenzyl) phosphonate as an electrolyte additive for LiNi0.5Mn1.5O4 cathode for high-voltage Li-ion battery

“…The addition of DLPP in STD electrolyte suppresses the side reactions, forms a thinner CEI layer and improves the structural stability of electrode material. Furthermore, the formed CEI layer with DLPP additive restrains the HF corrosion and reduce the transition metal dissolution, thus enhancing the cycling performances of the battery [11,12] .…”

Perspective on Recent Advances of Functional Electrolytes for Lithium Metal Batteries

“…(a) Schematic representation of the HOMO and LUMO energy levels of EC, DEC, NFSALi, and NFSA – anion. Panel a was reproduced with permission from ref . Copyright 2023 Wiley.…”

“…Suitable additives not only generate a SEI to protect the negative electrode but also have the function of stabilizing the positive electrode interface. Qian et al 85 presented an acidic additive, nonafluorobutane-1-sulfonic acid (NFSA), for highvoltage (5 V level LiNi 0.5 Mn 1.5 O 4 , noted as LNMO) LMBs. Raman tests confirmed the localized high-concentration distribution, such as the signals of −CF 3 and −SO 3 being stronger near the cathode/anode surfaces than those in the bulk electrolyte.…”

Nonflammable Electrolyte Enables High-Performance Phosphorus Anode for High-Safety Lithium-Ion Battery

“…Furthermore, the safer spinel LiNi 0.5 Mn 1.5 O 4 (LNMO) cathode that is paired with the P/C anode can improve both the operating voltage and the energy density of cells. However, its high operating voltage of 4.7 V enhances the difficulty of the design of the electrolyte. − Unfortunately, there is currently no electrolyte that can meet the requirements of the phosphorus anodes and high-voltage cathodes at the same time.…”