Metallic and complex hydrides may act as anode and solid electrolytes in next generation of lithium batteries. Based on the conversion reaction with lithium to form LiH, Mg- and Ti-based anode materials have been tested in half-cell configuration with solid electrolytes derived from the hexagonal high temperature modification of the complex hydride LiBH ₄ . These anode materials show large first discharge capacities demonstrating their ability to react with lithium. Reversibility remains more challenging though possible for a few dozen cycles. The work has been extended to full-cell configuration by coupling metallic lithium with positive electrodes such as sulfur or titanium disulfide through complex hydride solid electrolytes. Beside pure LiBH ₄ which works only above 120 °C, various strategies like substitution, nanoconfinement and sulfide addition have allowed to lower the working temperature around 50 °C. In addition, use of lithium closo-boranes has been attempted. These results break new research ground in the field of solid-state lithium batteries. Finally, operando and in-situ neutron scattering methods applied to full-cells are presented as powerful tools to investigate and understand the reaction mechanisms taking place in working batteries.