Stabilizing nucleation seeds in Li metal anode via ion-selective graphene oxide interfaces

Abstract

Inhomogeneous lithium deposition is an intractable issue that would cause the uncontrollable formation of lithium dendrites, triggering the cycle-life and safety concern of lithium-metal batteries. Constructing lithiophilic sites is considered as an effective approach to modify the lithiophobic Cu current collector. However, whether the lithiophilic site is stable or can sustainably regulate the lithium deposition in the long-term cycling still keeps unknown. Herein, we conceive a unique “sandwich” anode composed of nanoscale Zn metals uniformly confined between GO and Cu foil. In such a unique structure the middle layer of lithiophilic Zn nanoparticles as a nucleation seed facilitates the deposition of lithium to form a zinc-lithium alloy, while the GO layer at the interface not only provides a channel for the rapid transport of lithium ions, but also has strong adsorption properties with Zn to ensure the stability of the nucleation seed during long-term cycling. As a result, the GO-protected alloy composite anode has a smaller overpotential and more stable cycling than the pure alloy anode and the graphene-protected unalloyed anode. Consequently, a high Coulombic efficiency above 98% for 200 cycles at 1 ​mA ​cm-2 and a prolonged lifespan of symmetrical cells for 600 ​h ​at 1 ​mA ​cm-2 with lower polarization are achieved, which further renders the commercial LiFePO4 (LFP) based full cell cathode (11.5 mg cm-2) with high rate capacity of 90 mAh g-1 at 5 C) and high capacity retention of 81.1% at 1 C after 100 cycles. This work provides a new insight into high-efficiency Li storage by sustainable alloy sites.