Secondary lithium ion cell or battery, and protecting circuit, electronic device and charging device of the same

Abstract

The present invention provides a new method for improving capacity, average operating voltage and specific energy of a secondary lithium ion cell or battery. This method is achieved by means of properly adjusting the ratio between a positive material and negative material, which is calculated by theoretical specific energy, and properly increasing charge cut-off voltage. The present method can greatly increasing specific energy and average operating voltage of a secondary lithium ion cell without influence on recycle property of the cell. The present invention also provides a secondary lithium ion cell or battery practicing the method, a protecting circuit adapted for the secondary lithium ion cell or battery, a electronic device using said protecting circuit and said secondary lithium ion cell or battery, and a charging device for the secondary lithium ion cell or battery.

1 . A secondary lithium ion cell or battery, characterized in that the single secondary lithium ion cell has a charge cut-off voltage of greater than 4.2 V but less than 5.8 V, and the ratio of positive electrode material to negative electrode material of the single cell is from 1:1.0 to 1:2.5, as calculated by the theoretic capacity with the charge cut-off voltage set at 4.2 V 
     
     
         2 . A protecting circuit for the secondary lithium ion cell or battery according to  claim 1 , characterized in that the single lithium ion cell of said protecting circuit has a first overcharge protection voltage of greater than 4.35 V, and an overcharging protection release voltage of greater than 4.15 V. 
     
     
         3 . A protecting circuit according to  claim 2 , characterized in that the single lithium ion cell of said protecting circuit has a first overcharge protection voltage of greater than 4.45 V, and an overcharge protection release voltage of greater than 4.25 V 
     
     
         4 . An electronic device using a secondary lithium ion cell or battery as energy source, characterized in that said electronic device comprises a protecting circuit, wherein the single lithium ion cell has a first overcharging protection voltage of greater than 4.35 V, and an overcharge protection release voltage of greater than 4.15 V. 
     
     
         5 . An electronic device according to  claim 4 , characterized in that said electronic device comprises a protecting circuit, wherein the single lithium ion cell has a first overcharging protection voltage of greater than 4.45 V, and an overcharge protection release voltage of greater than 4.25 V. 
     
     
         6 . A charging device for a secondary lithium ion cell or battery, characterized in that said charging device controls a charge cut-off voltage to the single lithium ion cell within the range of greater than 4.3 V but less than 5.8 V. 
     
     
         7 . A charging device according to  claim 6 , characterized in that said charging device controls a charge cut-off voltage to the single lithium ion cell within the range from 4.3 V to 5.2 V. 
     
     
         8 . A charging device according to  claim 6 , characterized in that said charging device controls a charge cut-off voltage to the single lithium ion cell within the range from 4.3 V to 4.8 V.