4. Conclusion

The aim of this article was to convey some of the chemical bonding concepts used in theoretical chemistry to understand the physico-chemical properties of crystalline solids. Applied to the field of electrode materials for lithium batteries, these concepts can steer solid-state chemists and electrochemists towards materials other than those they would tend to consider the most promising, based on an ionic description of chemical bonding. Although the electrochemical performance of transition metal phosphides is still considered insufficient by the Li-ion battery industry, particularly for reasons of poor cycling performance, excessive polarization and toxicity when exposed to air, these materials are model electrodes that have paved the way for other energy storage mechanisms.

In this field, almost everything remains to be done. In a world governed by the "ever...