Electrochemical energy storage has become an increasingly vital component of modern society ever present in both portable electronics and transportation, as well as becoming important in the realisation of a fully renewable energy grid. The dominating type ofrechargeable battery rely on Li-ions which intercalating into an anode upon charging, typically graphitic 1 , migrate back to a cathode ( for example: LiCoO 2 2 , LiFePO 4 3,4 (LFP), or LiNi x Mn y Co 1-x-y O 2 (NMC) ) upon discharging, and a liquid/polymer electrolyte such as LiTFSI. These electrolytes typically possess desirable conductivities of the order of 10 -2 S cm -1 . However, they present significant safety risks due to their flammable nature. Further disadvantages are formation of potentially rate limiting solidelectrolyte interphases, simultaneous anion diffusion , lower operating voltages , and dendrite formation causing incompatibility with Li-metal anodes with ∼ 10× the capacity of current graphitic anodes ). The use of a solid-state electrolyte (SSE) is therefore desirable as it fixes many of these problems simultaneously. Current solid electrolyte materials include e.g. the Li-rich garnets such as Li 7 La 3 Zr 2 O 12 (LLZO) , the Argyrodites Li 6 MS 5 X (M=S,Se,X=Cl,Br,I) , Li 10 GeP 2 S 12 (LGPS) , as well as Li x P y O z N * benjamin.williamson@ntnu.no (LiPON) . Unfortunately, these materials possess a tradeoff between stability and conductivity. LiPON, for example, possesses excellent electrochemical stability and resistance towards dendrite formation , yet poor/mediocre conductivities of the order of 10 -6 S cm -1 are typically observed ), making it suitable for small scale devices or as a protective layer in conventional lithium battery cells. Whilst a lower conductivity would intuitively be expected in the solid state compared to the liquid state, competitively high conductivities (> 10 -3 S cm -3 ) are observed for some solid state materials. However, some expected issues do arise with respect to stability and synthesis of these materials. Within the past decade, Li-rich anti-perovskites, such as Li 3 OCl have gained a lot of interest due to their initial high reported ionic conductivities at ambient conditions (10 -3 S cm -1 ) as reported by Zhao and Daemen . Subsequent experimental and density functional theory (DFT) studies, however, have placed the conductivity to be much lower with a higher migration barrier(∼ 0.6 eV and 10 -6 S cm -127, ). Both nominally Li 3 OCl and Li 3 OBr have been shown to possess wide electrochemical stability windows even if they are metastable and not in a global ground state. This has been attributed due to its lack of reducible cations to Li-metal, yet may form Li 2 O and LiCl/Br at the anode. Additional antiperovskite ionic conductor compositions have been reported including, Na 3 OCl/Br , Na 3 SI 32 and Na 3 HS 33 to name a few.