Is it safe to charge a LiPo battery with a Li-ion battery charger circuit?
The recommended upper voltage limit is 4.2V for Li-Ion and Li-Po. One also needs to ensure that the current is appropriate for the battery's capacity. The recommended charge rate for Li-Po is ~1C, meaning that a battery with a capacity of X Amp-hours should be charged at X Amps (or less). The datasheet for your charging chip shows a maximum programmable output current of 1 Amp, which is less than the maximum permitted for your 1.55 Amp-hour battery.