You can use the WordPress function get_the_terms() to get list of terms without the HTML included. Then use a for loop to iterate through array of terms and add the term slug/name to the custom <div> tag. For example:
{% set term_list = mb.get_the_terms( post.ID, 'thematique' ) %}
{% for term in term_list %}
<div class="term-item {{ term.slug }}">
{{ term.name }}
</div>
{% endfor %}