Additives Engineered Nonflammable Electrolyte for Safer Potassium Ion Batteries

Abstract

Potassium ion batteries (KIBs) are attracting great attention as an alternative to lithium-ion batteries due to lower cost and better global sustainability of potassium. However, designing electrolytes compatible with the graphite anode and addressing the safety issue of highly active potassium remains challenging. Herein, a new concept of using additives to engineer nonflammable electrolytes for safer KIBs is introduced. It is discovered that the additives, such as the ethylene sulfate (i.e., DTD), can make the electrolyte of 1.0 m potassium bis(fluorosulfonyl) imide in trimethyl phosphate compatible with graphite anode for the first time, without the need of concentrated electrolyte strategies. A new coordination mechanism of additives in the electrolyte is presented. It is shown that the additive can change the K + solvation structure and then determine the interfacial behaviors of K +-solvent on electrode interface, which are critical to affect the graphite performance (i.e., K +-solvent co-insertion, or K + (de-)intercalation). Then, an extremely high potassium storage capability is obtained in graphite electrode for potassium (ion) batteries, particularly the presented high-performance graphite|K 0.69 CrO 2 full battery fully demonstrates the practical application of this newly designed electrolyte. This additive-based strategy can offer more opportunities to tune the electrolyte properties and then serve for the more mobile ion battery system.

Low‐Temperature Electrolyte Design for Lithium‐Ion Batteries: Prospect and Challenges

“…This process can affect the low‐temperature performance. In detail, three important discoveries have been reported recently about the SEI and additive effect [91a,b,d,e] . Firstly, the role of the Li + solvation structure is dominant compared to that of the SEI to suppress the Li + ‐solvent co‐intercalation (Figure 11a) [91a] .…”

State-of-the-art anodes of potassium-ion batteries: synthesis, chemistry, and applications

“…Liu and his coworkers investigated the ammability of electrolytes by comparing conventional electrolytes and modied electrolytes with trimethyl phosphate (TMP) and ethylene sulfate as non-ammable solvent and functional additive, respectively. 98 As shown in Fig. 24f, compared with the traditional EC/DEC-based electrolyte, the TMP-based electrolyte with low viscosity (1.3 vs. 2.5 mPa s of propylene carbonate), wide operating temperature range (À46 to 197 C), and high ash point (148 C) was non-ammable and difficult to be ignited.…”

“…24f, compared with the traditional EC/DEC-based electrolyte, the TMP-based electrolyte with low viscosity (1.3 vs. 2.5 mPa s of propylene carbonate), wide operating temperature range (À46 to 197 C), and high ash point (148 C) was non-ammable and difficult to be ignited. 98,176,177 Moreover, Mao et al also proposed triethyl phosphate (TEP) as the sole solvent of potassium electrolyte due to its re-retardant property. 178 Owing to the weak solvation of potassium cations by TEP, the electrolyte demonstrated low viscosity as well as high conductivity.…”

Growth Mechanism of Micro/Nano Metal Dendrites and Cumulative Strategies for Countering Its Impacts in Metal Ion Batteries: A Review

“…Low-cost additives such as ethylene sulfate, propylene sulfate in phosphate, or sulfonyl-based electrolytes contribute to faster insertionexertion of K + with graphitic anodes. The additives modify the solvation structure of potassium ions and optimize the interface barrier while regulating dendrite puff-out [451]. Dimethyl methylphosphonate, trimethyl phosphate, trimethylsilyl) phosphate, hexamethoxycyclotriphosphazene, isopropyl phenyl diphenyl phosphate, and triphenylphosphate are some of the flame-retardant additives used in alkali Li, which may assist the functionalities of K-based batteries.…”