The model suggests that electrodes discharged up to the critical
fractional conversion become non-conducting and hence they
cannot be charged. The model developed here also suggests that if
conductivity can be established, say through additives, current can
pass through the battery, and such deep discharged electrodes can
be charged. This should be possible since charge transfer reaction
can occur on the unreacted active material's surface. This can also
be done if charge transfer reactions can occur on the surface of the
additives. In this connection, it may be noted that Liu et al.[24]
convert lead sulfate into active negative electrode by adding conducting carbons. Preparations based on this principle can produce
batteries with better specific energy density provided life is not
affected