Fast‐Charging Electrolyte: A Multiple Additives Strategy with 1,3,2‐Dioxathiolane 2,2‐Dioxide and Lithium Difluorophosphate for Commercial Graphite/LiFePO₄ Pouch Battery

Abstract

Safe fast‐charging lithium‐ion batteries (LIBs) can be achieved by using LiFePO4 electrode and optimized electrolyte for the rapid development of electric vehicles. However, conventional carbonate electrolyte suffers resistive solid electrolyte interphase (SEI) that hampering the fast‐charging for LIBs. Herein, a multiple additive strategy, the combination of 1,3,2‐Dioxathiolane 2,2‐dioxide (DTD) and lithium difluorophosphate (DFP), is proposed to optimize the electrode interface for graphite (Gr)/LiFePO4(LFP) pouch cells under fast‐charging. Combining DTD with DFP can significantly reduce the charge transfer resistance of anode and greatly extend the lifespan of cells with >2400 cycles at a 2 C rate, which is much better than that of baseline and single additive based electrolytes with <1000 cycles. Further mechanistic studies revealed that proper sulfurized and phosphatized species are involved in the SEI film, which stabilizes lithium carbonate in the middle of SEI to avoid being attacked by Lewis acids. Multiple additive strategies optimize the interfacial structure and provide valuable guidance for the development of safe fast‐charging engineering.

Fast‐charging of lithium‐ion batteries: A review of electrolyte design aspects

“…This is largely due to their enhanced conductivity, which decreases charge transfer resistance and promotes the formation of a stable SEI. 61 Moreover, the presence of electrolyte additives contributes to dense SEI with good mechanical properties, which can mitigate the formation of lithium dendrites and the volume expansion of the anode during fast charging. 62 Son et al 63 studied the effects of EC, vinylene carbonate (VC) and fluoroethylene carbonate (FEC) additives on the fastcharging performance of LiNi 0.6 Co 0.2 Mn 0.2 O 2 (NCM)/graphite full batteries.…”

“…Many studies have demonstrated that the addition of additives significantly enhances rate‐performance and prevents degradation of LIBs. This is largely due to their enhanced conductivity, which decreases charge transfer resistance and promotes the formation of a stable SEI 61 . Moreover, the presence of electrolyte additives contributes to dense SEI with good mechanical properties, which can mitigate the formation of lithium dendrites and the volume expansion of the anode during fast charging 62 .…”

Enhanced LiMn0.8Fe0.2PO4 Cathode Performance Enabled by the 1,3,2-Dioxathiolane-2,2-dioxide Electrolyte Additive

“…In this respect, introducing small amounts of functional additives into electrolytes has long been considered a convenient, economical, and effective route, and a variety of functional electrolyte additives have been already investigated. − Among these additives, ethylene sulfate (1,3,2-dioxathiolane-2,2-dioxide (DTD)) is commercially utilized, the effect of which on the performance of LIBs has been widely studied. − Although it is well acknowledged that the benefits brought by DTD as an electrolyte additive on the anode for LIBs have been verified, the underlying mechanisms in different cathodes and cell systems are quite different. Dahn et al reported the benefits of DTD in combination with vinylene carbonate (VC) for LiNi 1/3 Mn 1/3 Co 1/3 O 2 /graphite pouch cells but not as well for LiCoO 2 /graphite pouch cells .…”

“…Moreover, Li et al optimized the performance of the layered LiNi 0.5 Co 0.2 Mn 0.3 O 2 cathode upon the single addition of DTD . Recently, Hu et al proposed a multiple additive strategy that combines DTD with lithium difluorophosphate (DFP), which helps to modify the electrode interface in LiFePO 4 /graphite pouch cells . However, the insight into the role of DTD additive working in a separated mode was unclear yet.…”