Antiperovskites of composition M₃AB (M = Li, Na, K; A = O; B = Cl, Br, I, NO₂, etc.) have recently been investigated as solid-state electrolytes for all-solid-state batteries. Inspired by the impressive ionic conductivities of Li₃OCl_0.5Br_0.5 and Na₃OBH₄ as high as 10^–3 S/cm at room temperature, many variants of antiperovskite-based Li-ion and Na-ion conductors have been reported, and K-ion antiperovskites are emerging. These materials exhibit low melting points and thus have the advantages of easy processing into films and intimate contacts with electrodes. However, there are also issues in interpreting the stellar materials and reproducing their high ionic conductivities. Therefore, we think a critical review can be useful for summarizing the current results, pointing out the potential issues, and discussing best practices for future research. In this critical review, we first overview the reported compositions, structural stabilities, and ionic conductivities of antiperovskites. We then discuss the different conduction mechanisms that have been proposed, including the partial melting of cations and the paddlewheel mechanism for cluster anions. We close by reviewing the use of antiperovskites in batteries and suggest some practices for the community to consider.

Small elevated experimental raceways have been used at many research sites in the United States to evaluate algal biomass productivity. This paper evaluates whether the productivities measured in these raceways are representative of large-scale commercial raceways. Open water surface evaporation and temperature models with shading algorithms were programmed in Python programming language and calibrated with temperature and evaporation data from the elevated experimental paddlewheel raceways in the Regional Algal Feedstock Testbed (RAFT) experiments at the University of Arizona. The final calibrated model for elevated experimental raceways was named the EERTEM (Elevated Experimental Raceway Temperature and Evaporation Model). The energy balance algorithms in the Biomass Assessment Tool (BAT) were added to the Python code and used to simulate temperature in standard commercial paddlewheel raceways. A comparison of BAT and EERTEM simulations indicated that elevated paddlewheel raceway temperature fluctuations are not representative of in ground commercial paddlewheel raceways, primarily due to the buffering effect of soil heat flux. The Huesemann Algae Biomass Growth (HABG) model simulated biomass productivities of three algae species with the BAT and EERTEM temperature profiles for the commercial and elevated experimental raceways, respectively. Differences in productivity were observed when the maximum daytime temperature of one raceway was in the optimal growth range but the temperature of the other raceway exceeded or was below the optimal growth range. If both raceway temperatures were in the optimal growth range for a given species, even if they had different temperatures, then there was minimal difference in growth. In summary, the EERTEM is not an accurate representation of commercial raceway productivity.