Surface Work Function Modifier to Modulate Electrolyte Decomposition on Negative Electrode in Lithium-Ion Batteries

The persistent decomposition of electrolytes on graphite and silicon electrodes in lithium-ion batteries (LIBs) is typically mitigated by the formation of a solid electrolyte interphase (SEI). However, the inadequate formation and chemo-mechanical degradation of SEI leads to re-exposure of electrode to electrolyte, contributing to the deterioration of LIBs. To address this issue, tris(2,4-pentanedionato)indium(III) (InAc) is incorporated into the work function tailoring additive. While conventional additives strengthen the chemo-mechanical properties of SEI through compositional modifications derived from specific elements, InAc uniquely alters charge transfer across the electrode surface, facilitated by high or low work function layer. This additive establishes an interlayer between the SEI and graphite/SiO surfaces, attributed to its tailored lowest unoccupied molecular orbital energy level. Consequently, the exposure of graphite surface to the electrolyte is minimized by interlayer during cycling. The interlayer possesses a higher work function than lithiated graphite and suppresses further electrolyte decomposition on graphite. In contrast, the interlayer on SiO decreases work function of SiO surface, which promotes the formation of inorganic SEI on SiO. Hence the degradation of SEI is suppressed with LiIn layer at SiO electrode. This leads to a reduction in the ongoing accumulation of SEI, thereby enhancing durability of LIBs. The work function-tailoring additive decreases the charge transfer through the exposed electrode surface from the high work function exhibiting interlayer, whereas typical electrolyte additives reinforce the chemo-mechanical properties of the SEI by compositionally changing from specific elements of functional additives. image