bq25504EVM not able to charge battery from zero V to 3 V

First I would suggest you to start with another battery. It looks like your battery can be damaged since most batterys should not have such a low voltage as 0.1V.

Since VSTOR is below than 1.8V, it is still in cold start mode.  The FET between VSTOR and VBAT stay open if the voltage on VSTOR is lower than VBAT_UV threshold. Thus your battery will not get charged if VSTOR is lower than VBAT_UV. What is your input source? How much input power is available at VIN_DC? 

I really appreciate for your reply.
The battery has 0.1 V because it is a battery I fabricated.
The input source is a solar cell with 0.45 mW. The input power available at Vin_dc is 0.2 -0.4 mW.
My concerns are:
1. Do I need to connect the battery only after the Vstor reaches higher than Vbat_uv?
2. Can the Vstor reach higher than Vbat_uv without any load and battery connected?
3. Do I need to change resistors to get a lower Vbat_uv for charging the battery?

Thanks.
Any help will be greatly appreciated.

Regarding 1, no, you do not need to. What I meant is the voltage on VSTOR is lower than VBAT_UV, then the internal FET between VBAT and VSTOR is open which disconnects the VBAT and VSTOR.
Regarding 2, yes, VSTOR should be able to reach all the way up tp VBAT_OV when the input power*efficiency is greater than the power draw by the load. You will need input voltage higher than 330mV for the part to operate in the cold start. Then the cold start circuit initially clamps VIN_DC to VIN(CS) = 330 mV typical. If sufficient input power (i.e.,output current from the harvester clamped to VIN(CS)) is not available, it is possible that the cold start circuit cannot raise the VSTOR voltage above VSTOR_CHGEN in order for the main boost conveter to start up. It is highly recommended to add an external PFET between the system load and VSTOR. An inverted VBAT_OK signal can be used to drive the gate of this system-isolating, external PFET.
Regarding 3, yes, you can change resistors for a lower VBAT_UV setting to fit your special battery. However, the lower limit on VBAT_UV is 2.2 mV.

thank you again,

I have no load connected at Vstor pin. I only have the battery connected at Vbatt pin.
1. So, the battery will be charged only if Vstor>Vbatt_uv (2.2 V default on the EVM)?
2. If the input power to the Vin dc pin is 200 microwatt with no load connected at Vstor pin, can the Vstor be raised beyond Vstor_chgen (1.8 V) and Vbatt_uv (2.2 V)?
3. Does the voltage at Vstor pin decrease when a battery is connected to Vbatt pin?
Really appreciate your help.

Thanks again for the reply.

i donot have any load connected to Vstor pin and only have battery connected to Vbatt pin.
My concerns are:
1. so the battery will not be charged if Vstor< Vbatt_uv?
2. If the input power to the Vin_dc pin is ~ 200 microwatts without any load at Vstor pin, can the Vstor be raised to greater than Vstor_chgen (1.8V) and Vbatt_uv (2.2 V default in EVM)?
3. does the voltage at Vstor pin decrease if a battery is connected at the Vbatt pin?
Really appreciate your help.

Regarding 1, one correction, when VSTOR<VBAT_UV, the battery can still be charged since there is a diode path between VSTOR and VBAT. Since the input current is very low the battery is drawing all the current, then you do not have much left to charge up VSTOR (IIN * efficiency = IBAT + IVSTOR).

Regarding 2, yes, as in my previous response, VSTOR can be charge up to VBAT_OV which is 5.5max. In your case, due to the limiatation of the input power, if you disconnect the battery, you should see VSTOR rise on the EVM.

Regarding 3, if you are connecting a 0.1V battery, once the internal FET between VBAT and VSTOR closes, VSTOR voltage will drop to your battery voltage.

You can try to experiment with the circuit below to rachet up the battery voltage without clapsing VSTOR.