a temperature sensor for battery heating system in cold environment
The temperature of the battery will not change by 0.2 degrees per second mostly likely. The ambient isn't all that important, I suspect. Accuracy of a degree C or two is probably fine.  

Also, you only need to sense accurately at a single point in the temperature scale, assuming that the sole purpose of the sensor is to make the heat/no heat decision. 

So I suspect the best system in your situation is a precision thermistor, an ADC on your microcontroller and a single precision resistor to the ADC reference (might be the supply rail). Even a 10 bit ADC will give you 50 or so counts per degree C at mid-scale, and accuracy can be quite good with a 1% thermistor. 

You can use the same kind of thermistor that is used in battery packs to monitor charging, mounted similarly.