Battery charging circuit using 12V dc generator
The IBL100-SW motor - description here and here and here
is a 3 phase brushless motor with DC input. This indicates that it has an internal controller. The electronics of the controller isolate the actual motor from the inputs and mean that it needs relatively minor / simple / low cost modification to make it suitable for use as an alternator or generator. You will need to open the motor and locate the controller to motor connections. 

The motor is probably connected to the controller by 3 or 4 wires. These are the 3 phase leads and perhaps a neutral lead. To use the motor as an alternator the 3 x phase connections from controller to motor should be electrically broken (unsoldered or unbolted or wires but or ...?) and the 3  x phase leads and neutral if present need to be brought out to the outside of the motor to act as alternator connections. 

The now available 3 phase output can be converted to DC by the use of diodes.
How many and how they are best connected depends on whether you have 3 or 4 wires.
With 3 wires, for each phase wire you connect a diode (anode to motor) to DC+ output and a diode (Cathode to motor) to DC- output.
With 4 wires you can do the same, but the neutral wire provides a mid point V/2 volts below and above the V+ and V- outputs respectively. 

For initial testing you can use any two wires plus a single diode to determine if the motor is producing the order of output expected. 

Depending on which web page you read the motor is rated at 500  to 1000+ Watts as a motor at nominal 36V, so as a rectified alternator you should get at least hundreds of Watts at rated speed.