Perfluoro Macrocyclic Ether as an Ambifunctional Additive for High‐Performance SiO and Nickel 88%‐Based High‐Energy Li‐ion Battery

Abstract State‐of‐the‐art lithium (Li)‐ion batteries employ silicon anode active material at a limited fraction while strongly relying on fluoroethylene carbonate (FEC) electrolyte additive exceeding 10 wt.% to enable stable cycling. The swelling issue of silicon in the aspect of solid electrolyte interphase (SEI) instability and a risk of safety hazards and high manufacturing cost due to FEC has motivated the authors to design a well‐working fluorinated additive substitute. High‐capacity cells employing nickel‐rich oxide cathode are pursued by operating at > 4.2 V versus Li/Li + , for which anodic stability of electrolyte is required. Herein, a highly effective new ambifunctional additive of icosafluoro‐15‐crown 5‐ether is proposed at a little fraction of 0.4 wt.% for the stabilized interfaces and reduced swelling of high capacity (3.5 mAh cm −2 ) 5 wt.% SiO‐graphite anode and LiNi 0.88 Co 0.08 Mn 0.04 O 2 cathode. Utilizing together with a lowered fraction of FEC, reversible long 300 cycles at 4.35 V and 1 C (225 mA g −1 ) are achieved. Material characterization results reveal that such stabilization is derived from the surface passivation of both anode and cathode with perfluoro ether, LiF, and Li x PF y species. The present study gives insight into electrolyte formulation design with lower cost and both‐side stabilization strategies for silicon and nickel‐rich active materials and their interfaces.