Reversible Switch in Charge Storage Enabled by Selective Ion Transport in Solid Electrolyte Interphase

Solid-electrolyte interphases (SEIs) in advancedrechargeablebatteries ensure reversible electrode reactions at extreme potentialsbeyond the thermodynamic stability limits of electrolytes by insulatingelectrons while allowing the transport of working ions. Such selectiveion transport occurs naturally in biological cell membranes as a ubiquitousprerequisite of many life processes and a foundation of biodiversity.In addition, cell membranes can selectively open and close the ionchannels in response to external stimuli (e.g., electrical, chemical,mechanical, and thermal), giving rise to gating mechanismsthat help manage intracellular reactions. We wondered whether thechemistry and structure of SEIs can mimic those of cell membranes,such that ion gating can be replicated. That is, can SEIs realizea reversible switching between two electrochemical behaviors, i.e.,the ion intercalation chemistry of batteries and the ion adsorptionof capacitors? Herein, we report such SEIs that result in thermallyactivated selective ion transport. The function of open/close gateswitches is governed by the chemical and structural dynamics of SEIsunder different thermal conditions, with precise behaviors as conductingand insulating interphases that enable battery and capacitive processeswithin a finite temperature window. Such an ion gating function issynergistically contributed by Arrhenius-activated ion transport andSEI dissolution/regrowth. Following the understanding of this newmechanism, we then develop an electrochemical method to heal the SEIlayer in situ. The knowledge acquired in this work reveals the possibilityof hitherto unknown biomimetic properties of SEIs, which will guideus to leverage such complexities to design better SEIs for futurebattery chemistries.

Automated summary

Solid-electrolyte interphases (SEIs) in advanced rechargeable batteries can mimic the chemistry and structure of cell membranes, allowing for selective ion transport and regulating electrode reactions. Researchers have reported SEIs that exhibit thermally activated selective ion transport, functioning as open/close gate switches. This ion gating is achieved through Arrhenius-activated ion transport and SEI dissolution/regrowth. The understanding of this biomimetic property of SEIs can guide the design of better SEIs for future battery chemistries.