Open framework perovskite derivate SEI with fluorinated heterogeneous nanodomains for practical Li-metal pouch cells

Abstract

Tailored artificial solid electrolyte interphase (SEI) is favorable for the stabilization of Li metal batteries (LMBs) and Li anode dendrite suppression. Here, an open framework perovskite derivate SEI with fluorinated heterogeneous nanodomains is proposed. The nano-structural K3FeF6 perovskite coating on Li anode can spontaneously convert into the robust SEI composed of KF, LiF and Fe nanodomains. The introduction of KF and Fe components could enhance the interface conductivity around LiF domains in SEI, beneficial for the homogenization of Li-ion flux and Li-mass plating. The residual K3FeF6 component with 3D open channels (even after long-term cycling) can serve as isotropic porous modulator to reduce the local current density and mitigate the volume change of electrode. This perovskite modified Li anode enables a long cycling life of 1100 h under 2 mAh cm−2 capacity for Li||Li symmetric cells. The modified LMBs with LiNi0.8Co0.1Mn0.1O2 cathode exhibit the ultralong 3300 cycles at 1 C. The corresponding pouch cells based on thick cathode (30 mg cm−2) enable a reversible capacity as high as 1.5 Ah, corresponding to an energy density of 236 Wh kg−1 based on the weight of whole packet under the protocols of N/P ratio of 1.28 and E/C ratio of 4.23 g Ah−1.