In-doped Li7La3Zr2O12 nanofibers enhances electrochemical properties and conductivity of PEO-based composite electrolyte in all-solid-state lithium battery

Garnet type Li7La3Zr2O12 solid electrolyte exhibits excellent thermal stability and high ionic conductivity, which is an ideal solid electrolyte. However, it is found that the cubic phase is a high conductivity phase and the synthesis condition is harsh. Therefore, low temperature synthesis and partial element substitution are expected to prepare cubic phase LLZO. In this paper, the LLZO cubic phase structure is stabilized by electrospinning technology and high-priced cation substitution strategy, and the transportation efficiency of lithium ions is improved. The experimental results show that LLZO NFs inorganic filler with stable cubic phase structure is obtained when the molar amount of In3+ is 0.2. The In3+ with large ion radius replaces the Li+ inside the crystal, effectively increases the lithium vacancy concentration, and increases the Li+ transport path inside the crystal, and successfully doubles the ionic conductivity of the composite solid electrolyte at 60 °C (9.39 × 10−4 S/cm). The lithium ions migration number and electrochemical window were increased to 0.19 and 5.2 V respectively. With excellent cycle performance (60 °C), it can cycle 2000 cycles at a high rate of 0.5 C charge and discharge, and the Coulomb efficiency has been close to 100 %. Li|PL-LILZO NFs (0.2)|LFP all-solid-state lithium batteries can light small bulbs at room temperature and have practical application prospects. Therefore, in the composite electrolyte, the increase of the lithium ions pathway inside the active inorganic filler crystal will also improve the comprehensive performance of the composite electrolyte for preparation.