Integrated solid-state Li-metal batteries mediated by 3D mixed ion-electron conductive anodes and deformable molten interphase

The high reactivity of Li-anodes and the easily separated solid-state interface are two hurdles for constructing stable solid-state Li-metal batteries (SSLBs). Herein, we report a 3D mixed ion–electron conductive (MIEC) Li anode with deformable molten interphase of poly(Ɛ-caprolactone) electrolytes that is highly efficient towards constructing stable SSLBs. The 3D Li anode is fabricated by integrating a Li foil with a MIEC film via a facile hot-rolling process, in which the MIEC frame is composed of Li0.33La0.56TiO3 particle attached carbon nanofibers. We propose that the chemical reactions between Li0.33La0.56TiO3 and Li facilitates Li-nucleation inside the MIEC frame and thus enables fast stress relaxation and reduces volume fluctuations, while the molten interphase works as a binder to integrate the anodes and electrolytes without delamination during cycling. As a result, the symmetrical batteries run stably for 1200 h at 45 ℃, and the 3D Li/LiFePO4 full batteries achieve a capacity of 134 mA h g−1 at 1C with a high-capacity retention of 98 % after 250 cycles, showing appealing commercial prospect.