I am trying to understand the rate of charge of a rechargeable battery - let's say, a Li-ion one. What I'm interested in, is to understand whether the charge (the "percentage" of the Ampere-hours the battery can hold) in the battery is accumulated homogeneously over time. For example, if 2000 mAh battery takes 2 hours to get charged in a certain charging regime, whether after the first hour, it will act like a 1000 mAh battery.
It seems logic to me that if you keep the battery under constant current during the charging, then the rate of charging will be constant as well, but as the voltage of the battery changes over time - but what about other charging regimes? Is there any way for me to deduce charging rates from curves such as the one brought in Fig. 5 below (from A Designer's Guide to Lithium Battery Charging - DigiKey)?
Figure 5: Li-ion charging profile using constant current method until battery voltage reaches 4.1 V, followed by “top-up” using constant voltage technique. (Courtesy of National Semiconductor.)