How to overcome fastly and reliably the challenges to foster the lithium-based salts exploitation for latent heat storage technologies? In situ and real time microscopy is used to understand the discrepancies between the theoretical and experimental macroscopic properties of materials via the microscopic mechanisms. The feasibility of this method on the inorganic lithium salts is demonstrated despite their air/moisture-sensitivity and the common belief pretending that LiOH cannot be used for the synthesis of new materials inside the microscope chamber due to its decomposition in dry environment or under vacuum. The deviation source of ~30% from the theoretical energy density of 434 kWh/m3 has been investigated through the case study of Li4Br(OH)3, an uncommon promising phase change material. The hydration/dehydration of the starting materials appears as one of the main parameters, with applied temperature protocols, eliciting the deviation towards different materials from the targeted one of interest, in terms of morphology and properties. This criterion, if not taken into account, could be disastrous for the storage capacity of a unit during its use. This study highlights solutions to avoid these deficiencies. The results consistency at microscale with those obtained at macroscale is also proved despite the different operating conditions< Leer menos