Hydrides compounds for electrochemical applications

Hydrides have been used since a long time for solid-state hydrogen storage and electrochemical nickel-metal hydride batteries. Besides these applications, growing attention has been devoted to their development as anode materials, as well as solid electrolytes for Li-ion and other ion batteries. Herein, we review and summarize the recent advances of hydrides as negative electrodes for Ni-MH and A-ion batteries (A = Li, Na), and as electrolyte for all solid-state batteries (ASSB). Metallic hydrides such as intergrowth compounds are highlighted as the best compromise up to now for Ni-MH. Regarding anodes of Li-ion batteries, MgH2, especially its combination with TiH2, provides very promising results. Complex hydrides such as Liborohydride and related closo-borates and monovalent carborate boron clusters appear to be very attractive as solid electrolytes for Li-based ASSB, whereas closo-hydroborate sodium salts and closo-carboborates are investigated for Naand Mg-ASSB. Finally, further research directions are foreseen for hydrides in electrochemical applications.

Automated summary

Hydrides have been widely used in hydrogen storage and nickel-metal hydride batteries, but they have also shown potential as anode materials and solid electrolytes for various ion batteries. This review highlights the recent advances and applications of hydrides as negative electrodes in Ni-MH and A-ion batteries and as electrolytes in all solid-state batteries (ASSB). Metallic hydrides, especially intergrowth compounds, have been found to be the best compromise for Ni-MH batteries. MgH2, especially in combination with TiH2, shows promising results as anode materials for Li-ion batteries. Complex hydrides like Liborohydride and closo-borates have potential as solid electrolytes for Li-based ASSB, whereas closo-hydroborate sodium salts and closo-carboborates are being investigated for Na and Mg-ASSB. Further research directions for hydrides in electrochemical applications are also discussed.