context: In summary, we report a highly effective approach to prevent Li dendrite formation by an in situ formed self-repairing alloy layer (LixGa). During lithiation, evenly distributed Ga nanoparticles serve as lithiophilic sites to induce a homogeneous Li nucleation. Stress generated during Li plating can also be eliminated by the soft Ga nanoparticles. During the delithiation, metallic liquid Ga partially recovered from the dealloying process by timely filling the small gaps, which effectively avoided the generation of microcracks. A long-term cycling life of over 1800 h and 1400 h was obtained for the alloy-protected Li anodes at the high current densities of 2 mA cm−2 and 5 mA cm−2, respectively. Even increasing the current density and deposition capacity to 15 mA cm−2 and 15 mA h cm−2, respectively, the alloy-protected Li anodes still showed a stable cycling performance. Functionalized full cells coupled with LiFePO4 cathodes are finally cycled up to 600 cycles at 3C rate with the discharge capacity maintained at 128 mA h g−1. This simple and facile modification method is expected to realize the high-rate and long-life cycling of the Li metal anode and paves the way for the industrialization of Li metal batteries.
answer: LiFePO4 