Git gives your the control on how to format the log output using pretty option. Check this out:
git log --pretty=format:%h,%an,%ae,%s
This prints the log in the format of (hash [abbreviated], author name, author email, subject).
To see the full list of format options:
git help log
And scroll down until you see the list of format options.
To redirect the output, use > redirection operator as follows:
git log --pretty=format:%h,%an,%ae,%s > /path/to/file.csv