Alastair D. Robertson (122829)Peter G. Bruce (1500148)
Lithium intercalation compounds based on lithium manganese oxides are of great\nimportance as positive electrodes for rechargeable lithium batteries. It is widely accepted\nthat Li<sup>+</sup> may be extracted (deintercalated) from such lithium manganese oxides accompanied\nby oxidation of Mn up to a maximum oxidation state of +4. However, it has been suggested\nrecently that further Li<sup>+</sup> removal may be possible. Among the mechanisms that have been\nproposed to charge balance the removal of Li<sup>+</sup> are Mn oxidation beyond +4 or loss of O<sup>2-</sup>.\nTo investigate this phenomenon we have selected Li<sub>2</sub>MnO<sub>3</sub>, a layered compound Li[Li<sub>1/3</sub>Mn<sub>2/3</sub>]O<sub>2</sub>\nwith a ready supply of mobile Li<sup>+</sup> ions but with all Mn already in the +4 oxidation state.\nWe show that a substantial quantity of Li (at least 1.39 Li) may be removed. At 55 °C this\noccurs exclusively by oxidation of the nonaqueous electrolyte, thus generating H<sup>+</sup> which\nexchange one-for-one with Li<sup>+</sup> to form Li<sub>2</sub><sub>-</sub><i><sub>x</sub></i>H<i><sub>x</sub></i>MnO<sub>3</sub>. The presence of H<sup>+</sup> between the oxide\nlayers results in a change of the layer stacking from O3 to P3, the latter being more stable\nfor O−H−O bonding. At 30 °C initial Li removal is accompanied by oxygen loss (effective\nremoval of Li<sub>2</sub>O) but further Li<sup>+</sup> removal involves the same proton exchange mechanism as\nobserved at 55 °C. The reaction is partially reversible. On extended cycling the material\nconverts to spinel.
Niccoló Guerrini (3072987)Liyu Jin (1726735)Juan G. Lozano (5430386)Kun Luo (240608)Adam Sobkowiak (1767523)Kazuki Tsuruta (1885204)Felix Massel (3072990)Laurent-Claudius Duda (7866728)Matthew R. Roberts (1313802)Peter G. Bruce (1500148)
Rose E. Ruther (1512538)Hemant Dixit (1550776)Alan M. Pezeshki (1550782)Robert L. Sacci (1550779)Valentino R. Cooper (537435)Jagjit Nanda (1285947)Gabriel M. Veith (368520)
Hairong WangJun RenGuo Liang SunDi Cen
А. С. ТолкачеваM. А. Konopel’ko
Qinghua Cui (70819)Peng Zhang (2071)Jiawei Wang (158148)