▎ 摘　　要

Ceramic solid electrolytes are important emerging materials with the potential to enable the safe use of Li-metal anodes. However, they suffer from inherently low fracture toughness, which significantly limits battery performance and reliability. While small electrolyte dimensions are generally needed for faster ion transport, these length scales also restrict the approaches that can be used to engineer higher fracture resistance. Inspired by the toughening that reduced graphene oxide provides to polymers and engineering ceramics, this study explores the use of rGO to enhance the toughness of an oxide-based lithium-ion conductor. Materials with a greater than 2-fold enhancement in the average K-IC are demonstrated. To our knowledge, this is the toughest ceramic solid electrolyte yet reported. Based on these results, an analytical framework is developed to provide guidelines for the design of ultra-tough solid electrolytes using 2D materials.