Oriented Crystal\nGrowth of Li<sub>0.33</sub>La<sub>0.557</sub>TiO<sub>3</sub> Nanowire\nInduced by One-Dimensional Polymer\nSheath toward Rapid Lithium-Ion Transfer

Superionic conductor-based solid-state electrolytes with\npreferred\ncrystal structures hold great promise for realizing ultrafast lithium-ion\n(Li<sup>+</sup>) transfer, which is urgently desired for all-solid-state\nlithium batteries. However, the precise control of crystal growth\nof superionic conductors is still challenging since the crystals always\nspontaneously grow to disordered structures with the lowest internal\nenergy to ensure thermodynamic stability. Herein, a coaxial nanowire\nwith a polyvinylpyrrolidone (PVP) sheath and a Li<sub>0.33</sub>La<sub>0.557</sub>TiO<sub>3</sub> (LLTO) precursor core (PVP/LLTO-caNW)\nis prepared through coaxial electrospinning, followed by sintering\ninto LLTO nanowire with an oriented crystal structure (LLTO-caNW).\nWe demonstrate that the one-dimensional PVP sheath as a sacrificial\nlayer generates uniform and the strongest adsorption ability on the\n(110) phase among different LLTO crystal planes, which induces the\ncrystal to preferentially grow along the <i>c</i>-axis (the\nfastest Li<sup>+</sup> transfer direction) during the nucleation and\ngrowth processes. As a result, the prepared LLTO-caNW displays an\nultrahigh bulk ionic conductivity of 3.13 × 10<sup>–3</sup> S cm<sup>–1</sup>, exceeding most LLTO crystals and approaching\nthe theoretical conductivity. Meanwhile, the oriented crystal growth\nimparts to LLTO-caNW significantly reduced grain boundary resistance,\nand the grain-boundary conductivity reaches up to 1.09 × 10<sup>–3</sup> S cm<sup>–1</sup>. This endows the composite\nsolid electrolyte with high ionic conduction performance and superior\ncycle stability in the assembled all-solid-state lithium battery.