Microstructural engineering in lithium garnets by hot isostatic press to cordon lithium dendrite growth and negate interfacial resistance for all solid state battery applications

Hot isostatic press (HIP) post sintering technique was utilized on the garnet structured oxides, prepared by solid state reaction method, to enhance density, Li+ conductivity and barricade lithium dendrite growth. Simultaneous application of heat and isostatic pressure is an effective technique to enhance the grain boundary integrity and minimize the pores, which in turn, increase the relative density of the lithium garnet oxide pellets. The advantage of HIP is well echoed by the enhanced total (grain + grain boundary) Li+ conductivity and transparency of the Li6.16Al0.28Zr2La3O12 (Al-LLZ) pellet. The room temperature (25 degrees C) total lithium ion conductivity of Al-LLZ and 1 wt% of Li4SiO4 (LSO) added Al-LLZ, were found to be 0.13 mS/cm and 0.3 mS/cm, respectively. This is further enhanced to 0.31 mS/cm and 0.41 mS/cm, respectively, along with improved relative density of around 98% through the HIP treatment. The HIP treated transparent Al-LLZ pellet successfully barricades lithium dendrite growth even at higher current density of 250 mA/cm(2) and also reduces the metallic lithium and Al-LLZ interfacial resistance by increasing the lithium wettability. (C) 2019 Elsevier Ltd. All rights reserved.