Hi Nitish,
In general when you pass value to excel sheet cell system will consider field property as General field, this is one of the reason we will use xslt transformation to get the output as per the requirements. you just try below option, otherwise you have to go with transformation.
You can try converting the field into type i before doing the concatenation to the i_contents_bin.
suppose
if you want to see ls_data-f2 this field, define one new variable type i and then use conversion_exit_alpha_input fm by giving input as ls_data-f2 and out put new variable. Use this variable in concatenate statement instead of structure vairble.
Best Regards.
Dharmakasi.