Li7La3Zr2O12 Garnet Solid Polymer Electrolyte for Highly Stable All-Solid-State Batteries

Abstract

All-solid-state batteries have gained significant attention as promising candidates to replace liquid electrolytes in lithium-ion batteries for high safety, energy storage performance, and stability under elevated temperature conditions. However, the low ionic conductivity and unsuitability of lithium metal in solid polymer electrolytes is a critical problem. To resolve this, we used a cubic garnet oxide electrolyte (Li7La3Zr2O12 – LLZO) and ionic liquid in combination with a polymer electrolyte to produce a composite electrolyte membrane. By applying a solid polymer electrolyte on symmetric stainless steel, the composite electrolyte membrane shows high ionic conductivity at elevated temperatures. The effect of LLZO in suppressing lithium dendrite growth within the composite electrolyte was confirmed through symmetric lithium stripping/plating tests under various current densities showing small polarization voltages. The full cell with lithium iron phosphate as the cathode active material achieved a highest specific capacity of 137.4 mAh g−1 and a high capacity retention of 98.47% after 100 cycles at a current density of 50 mA g−1 and a temperature of 60°C. Moreover, the specific discharge capacities were 137 and 100.8 mAh g−1 at current densities of 100 and 200 mA g−1, respectively. This research highlights the capability of solid polymer electrolytes to suppress the evolution of lithium dendrites and enhance the performance of all-solid-state batteries.

Role of Filler Content and Morphology in LLZO/PEO Membranes

“…However, the interface resistance is still too high to promote Li-ion migration throughout the whole electrolyte. Hence, the Li solely migrates through PEO (Figure 1) (Chen et al, 2017;Zheng and Hu, 2018;Karthik and Murugan, 2019;Li et al, 2020b;Nguyen et al, 2020).…”

Ionic liquids in the scope of lithium-ion batteries: from current separator membranes to next generation sustainable solid polymer electrolytes

“…82 By adding ceramic garnet-type solid electrolyte Li 7 La 3 Zr 2 O 12 (LLZO) particles combined with the [MPPYR][TFSI] IL, successful suppression of the lithium dendrites growth was achieved, resulting in high-performance batteries with good cyclability at different discharge rates. 79 Furthermore, the use of graphene oxide (GO) contributes to anion immobilization in the SPE, reducing the growth of lithium dendrites due to a more uniform distribution of the charges during the cycling process, as schematized in Fig. 8.…”

Development on Solid Polymer Electrolytes for Electrochemical Devices

“…Filler-added SPEs are flexible, more stable and have better interfacial compatibility with Li metal electrodes [141,151]. Furthermore, the SPEs possess better processability and higher ionic conductivity than the solid electrolytes [151,152]. Similar to inactive fillers, the size, concentration and morphology of active fillers impose different impact on the CSPEs.…”

“…In the work of Keller et al [155], LLZO-added CSPE containing PEO and LiTFSI did not contribute to ionic conductivity but exhibited improved electrolyte-electrode interfacial contact and higher electrochemical performance in lithium battery. It was found that the addition of LLZO in SPEs suppressed lithium dendrites growth [152][153][154][155][156]. The lithium and zirconium sites of LLZO can be doped with other elements to boost its properties.…”