Binder Mitigating Current Collector Corrosion toward 5 V-Class Lithium Metal Batteries

Even with native aluminum oxide (Al₂O₃) passive film, the aluminum (Al) current collector is susceptible to pitting corrosion and anodic dissolution under high voltage (>4.0 V vs. Li⁺/Li). Herein, a corrosion-inhibiting binder (named as CSAP) with an ion-hydrogen bond synergistic network is developed for 5 V-class LiNi_0.5Mn_1.5O₄ (LNMO) batteries, the abundant carboxylate (─COO⁻) on the backbone plays a key role in coordinating with Al₂O₃, resulting in a stable organic–inorganic hybrid interphase that effectively resists the attack of corrosive species generated from lithium salt. Minor current response is exhibited from the CSAP-treated Al current collector compared with the poly(vinylidene fluoride) (PVDF) counterpart during 36 h chronoamperometry test, directly indicating the suppressed corrosion reactions. A similar conclusion can be arrived at from the lower content of corrosion mass loss in finite element analysis. Furthermore, the suppression of transition-metal ion dissolution endowed by CSAP is verified through the structural retention observed in scanning transmission electron microscopy (STEM). Benefiting from these merits, a discharge capacity of 139.4 mAh g⁻¹ is maintained in the LNMO/CSAP battery after 600 cycles at 1 C, compare with 109.7 mAh g⁻¹ of the PVDF counterpart. More encouragingly, a discharge capacity of 108.1 mAh g⁻¹ is exhibited for the LNMO/CSAP battery at 12 C.