Capacitor charge circuit - 0V drop switch?
Pick a diode with an even lower forward voltage, like LSM115J, which typically drops 80 mV at 10 mA. Your initial current will probably be much larger, but the low voltage drop only becomes important at the end of charging, when the current is much lower. Eventually the voltage drop will still decrease further as the current gets lower, so the ultimate voltage difference may be even lower. 

If the voltage is 12 V, then an 80 mV drop will cost you 1.3 % in the energy you can store.