Hi.
The diode D1, does it need to be a Vf~0.45 V for the circuit to keep the load off at daylight ?
Circuit is meant to turn 'load' on dusk to dawn and recharge cell from solar panel dawn to dusk. Look at the schematic only; text is chineseconfuser.
A normal silicon diode will work but it drops the voltage from the solar cell by a bit more than a Schottky diode. (About 0.2 volts more than a Schottky diode.)
I would NOT advise using that circuit with a lithium battery as there is no control of the charging voltage and current.
This picture is from a recent Big Clive video. The 18650 cells in two solar-powered LED lights burst out the end of the lights, apparently from not having any battery protection circuits.