Confining Highly Redox-Active Atoms in Stable Insertion-Type Anode Materials for Alkali Metal-Ion Batteries

The unique combination of exceptional energy and power density along with the continuous decrease in cost have made lithium-ion batteries the electrochemical energy storage technology of choice for small-scale and large-scale applications.^[1–3] However, the use of graphite as active material for the negative electrode is intrinsically limiting the possibility to rapidly charge these batteries.^[4] Herein, a new class of active materials is presented that provides comparable charge storage capacities at much faster rates. This new class of materials is based on the introduction of highly redox-active atomic centers into stable metal oxide host structures. These host structures are well preserved upon continuous lithium cation insertion and deinsertion following a solid-solution-type mechanism, while the introduction of these highly redox-active atomic centers allows for the duplication and triplication of the charge storage capacity compared to the nanoparticulate metal oxide host structures alone. Remarkably, the redox centers are reversibly reduced to the metallic state at the atomic level without affecting the surrounding crystal structure. When replacing lithium cations by sodium or potassium cations, essentially the same mechanism is observed, apart from the expected “size effect”, highlighting the exceptional versatility of this new class of battery electrode materials.<br/><br/><b>References</b><br/>[1] B. Scrosati, J. Garche, <i>Journal of Power Sources</i> <b>2010</b>, <i>195</i>, 2419.<br/>[2] B. Nykvist, M. Nilsson, <i>Nature Clim. Change</i> <b>2015</b>, <i>5</i>, 329.<br/>[3] M. Armand, P. Axmann, D. Bresser, M. Copley, K. Edström, C. Ekberg, D. Guyomard, B. Lestriez, P. Novák, M. Petranikova, W. Porcher, S. Trabesinger, M. Wohlfahrt-Mehrens, H. Zhang, <i>Journal of Power Sources</i> <b>2020</b>, <i>479</i>, 228708.<br/>[4] J. Asenbauer, T. Eisenmann, M. Kuenzel, A. Kazzazi, Z. Chen, D. Bresser, <i>Sustainable Energy Fuels</i> <b>2020</b>, <i>4</i>, 5363.