context: Fig. 2a shows the photographs of the PLB-CSE; the as-prepared membrane is free-standing and exhibits excellent ductility and flexibility. It is worth noting that the composite electrolyte membrane with such a high proportion of inorganic ceramic particles still exhibits great flexibility, and no cracks could be found in the electrolyte films upon bending, indicating an excellent mechanical capability. This flexible and strong PLB-CSE membrane can be used in flexible devices. To further analyze the microstructure morphologies and the distribution of LATP inorganic nanoparticles, the SEM image is presented in Fig. 2b. The SEM image shows a flat and homogeneous surface free of pores for the electrolyte membrane; the LATP ceramic fillers are uniformly dispersed in the polymer matrix. Fig. 2c displays the cross-sectional features of the PLB-CSE membrane, the thickness of which is about 60 μm, and the corresponding EDS mapping images of titanium (Ti), phosphorus (P), sulfur (S), and fluorine (F) are given in Fig. 2d–g. It can be observed that the LATP ceramic particles are uniformly dispersed in the electrolyte membrane, and the homogeneous LATP inorganic particles are in close contact with each other forming a continuous network structure, allowing Li-ion transfer between LATP ceramic grains, enabling a fast and efficient conductive pathway, which can promote ion transportation within the composite electrolyte.