The invention discloses a novel high-energy secondary aluminium cell and a preparation method. The aim is to provide a method for preparing nano material-coated negative electrode active materials, by coating the negative electrode active materials with the nano materials, it is possible to subject the negative electrode active materials to nano treatment; therefore, the high-energy secondary aluminium cell features obviously improved properties, simple material composition, low cost, simple technology, environmentally friendly synthesis path, relatively high charge-discharge capacity and relatively good cycle property and market prospect. The aluminium cell comprises the positive and negative electrodes in the modified positive and negative electrode active materials coated by the nano material surfaces or any one electrode in the singly coated positive or negative electrode active materials, polyelectrolyte (ionic liquid) and a diaphragm. The coating materials are semimetals, oxides, salts or conductive polymers. The invention uses the nano materials in the secondary aluminium cell for the first time; therefore, the cell has higher open circuit voltage and reversible capacity and better cycle property, can be applied to such fields as portable power sources like mobile telephones, notebooks and portable electronic components, and as electric vehicles, hybrid electric vehicles and the like, and has broad application and development prospects.