New cathode materials for rechargeable Mg batteries: fast Mg ion transport and reversible copper extrusion in Cu_yMo_6S_8 compounds

摘要

We report on a discovery of fast cathode materials, ternary Chevrel phases (CPs), Cu_yMo_6S_8, for rechargeable magnesium batteries; the related electrochemical process displays a unique coupling between reversible Mg insertion, and Cu extrusion/reinsertion; this coupling results in an entirely new intercalation mechanism which combines the total chemical reversibility of the electrochemical reaction of Mg_xCu_yMo_6S_8 with irreversi-bility of its separate stages once Cu extrusion stage is reached (in Mg_xCu_yMo_6S_8: 0.5 x + y ＞ 4).