Improving the fast-charging capability of NbWO-based Li-ion batteries.

The discovery of Nb-W-O materials years ago marks the milestone of charging a lithium-ion battery in minutes. Nevertheless, for many applications, charging lithium-ion battery within one minute is urgently demanded, the bottleneck of which largely lies in the lack of fundamental understanding of Li storage mechanisms in these materials. Herein, by visualizing Li intercalated into representative NbWO, we find that the fast-charging nature of such material originates from an interesting rate-dependent lattice relaxation process associated with the Jahn-Teller effect. Furthermore, in situ electron microscopy further reveals a directional, [010]-preferred Li transport mechanism in NbWO crystals being the "bottleneck" toward fast charging that deprives the entry of any desolvated Li through the prevailing non-(010) surfaces. Hence, we propose a machine learning-assisted interface engineering strategy to swiftly collect desolvated Li and relocate them to (010) surfaces for their fast intercalation. As a result, a capacity of ≈ 116 mAh g (68.5% of the theoretical capacity) at 80 C (45 s) is achieved when coupled with a Li negative electrode.