%0 Journal Article
%A Mitchell, Nicole C.
%A Thomas, Oliver O.
%A Meyer, Benjamin G.
%A Garcia-Fernandez, Mirian
%A Zhou, Ke-Jin
%A Grant, Patrick S.
%A Bruce, Peter G.
%A Heap, Richard
%A Sayers, Ruth
%A House, Robert
%T Influence of Ion Size on Structure and Redox Chemistry in Na‐Rich and Li‐Rich Disordered Rocksalt Battery Cathodes
%J Advanced materials
%V 37
%N 32
%@ 0935-9648
%C Weinheim
%I Wiley-VCH
%M PUBDB-2025-04469
%P 2419878
%D 2025
%X Li-rich disordered rocksalts are promising next-generation cathode materials for Li-ion batteries. Recent reports have shown it is also possible to obtain Na-rich disordered rocksalts, however, it is currently poorly understood how the knowledge of the structural and redox chemistry translates from the Li-rich to the Na-rich analogs. Here, the properties of Li2MnO2F and Na2MnO2F are compared, which have different ion sizes (Li+ = 0.76 vs Na+ = 1.02 Å) but the same disordered rocksalt structure and stoichiometry. It is found that Na2MnO2F exhibits lower voltage Mn- and O-redox couples, opening access to a wider compositional range within the same voltage limits. Furthermore, the intercalation mechanism switches from predominantly single-phase solid solution behavior in Li2MnO2F to a two-phase transition in Na2MnO2F, accompanied by a greater decrease in the average Mn─O/F bond length. Li2MnO2F retains its long-range disordered rocksalt structure throughout the first cycle. In contrast, Na2MnO2F becomes completely amorphous during charge and develops a local structure characteristic of a post-spinel. This amorphization is partially reversible on discharge. The results show how the ion intercalation behavior of disordered rocksalts differs dramatically when changing from Li- to Na-ions and offers routes to control the electrochemical properties of these high-energy-density cathodes. 
%F PUB:(DE-HGF)16
%9 Journal Article
%R 10.1002/adma.202419878
%U https://bib-pubdb1.desy.de/record/639375