Achieving Enhanced High-Temperature Performance of Lithium-Ion Batteries via Salt-Inspired Interfacial Engineering

Electrolyte additive engineering enables the creation of long-lasting interfacial layers that protect electrodes, thus extending the lifetime of high-energy lithium-ion batteries employing Ni-rich Li[Ni_1-x-yCo_xMn_y]O₂ (NCM) cathodes. However, batteries face various limitations if existing additives are employed alone without an appropriate combination. Herein, the study reports the development of a molecular-engineered salt-type multifunctional additive, lithium bis(phosphorodifluoridate) triethylammonium ethenesulfonate (LiPENS), that leverages the different functionalities of phosphorous, nitrogen, and sulfur-embedded motifs, as well as the classical additive vinylene carbonate (VC), to construct protective interfacial layers. The thermally and electrochemically reinforced solid electrolyte interphase (SEI), achieved through the combined use of LiPENS and VC, conserves the lithiation level of the Graphite (Gr) anode with minimal SEI growth, whereas the inorganic-rich cathode-electrolyte interface (CEI) alleviates the irrevocable phase transition and mechanical fragility of the LiNi_0.8Co_0.1Mn_0.1O₂ (NCM811) secondary particles. The multifunctional roles of LiPENS are demonstrated in an NCM811/Gr full cell, showing a discharge capacity of 190.7 mAh g^-1 with an enhanced capacity retention of 91.8% at 1 C and 45 °C after 300 cycles. This advancement in electrolyte additive engineering based on salt structures can lead to more efficient, reliable, and commercially viable batteries for high-energy applications, including electric vehicles and portable electronics.