| 摘要 |
1,191,318. Positive electrodes having principal and secondary active materials. ESB Inc. 19 July, 1967 [20 July, 1966 (2)], No. 33150/67. Heading H1B. A positive electrode comprises a principal active material and a secondary active material in the form of a layer which masks the principal active material from the electrolyte and which is stable in the electrolyte and in its undischarged state is electrolyte-impermeable but on discharge becomes permeable, permitting access of the electrolyte to the principal active material. Preferably the secondary active material is in electronic contact with the principal active material, has a lower potential than the principal active material, and has a discharge product that is oxidizable thereby, so that on discharge electrolyte is admitted to the principal active material which then reoxidizes the secondary active material and is itself reduced, the electrode thus developing the potential associated with the secondary electrode throughout discharge. Suitable combinations of principal and secondary active material are AgO-Ag 2 O; AgO-HgO; AgOMuO 2 ; KMnO 4 -Ag 2 O; and KMnO 4 -HgO; other suitable principal active materials are CuO and S. In Fig. 2, which differs from Fig. 1, only in the presence of the optional layer 20, the lid (2) is tin-plated steel containing the negative electrode (8) of finely-divided amalgamated zinc; this is separated by an electrolyte absorbent layer (9) of, e.g. matted cotton fibres, and a membrane barrier (10) of, e.g. " Cellophane " (Registered Trade Mark) or polyethylene or PVC containing a polyelectrolyte from the masking layer (12) of Ag2O, dispersed in a continuous phase in styrene, under which lies the main body (11) of the principal active material AgO, housed in the nickelplated steel cup (31); the optional layer (20) between the main body (11) and the cup (3) is of the secondary active material Ag 2 O, and functions as described in Specification 1,154,837, being re-oxidized, on discharge, by the principal active material and maintaining the electrode potential at the Ag 2 O-Zn value throughout discharge. |
