摘要 |
A secondary cell includes as its active cathode material a first insertion material, such as V6O13, into which ions are inserted during discharge. To prevent irreversible lattice changes leading to a decline in capacity the discharge should be terminated before a threshold cell voltage is crossed. Such irreversible changes are suppressed by including in the cathode a minor proportion of a second insertion material, such as a titanium oxide, whose discharge commences before the threshold cell voltage is reached. |