Can I use first person 'I' in an academic essay?
Academic essays are typically written in an objective and formal tone. The usual advice is to generally avoid using the first-person pronoun (e.g. I or we); although this is becoming more acceptable and may be required in some essay assignments.
What are other features of academic style?
In a formal style, especially when working to a word count, full forms are preferred over abbreviated or contracted forms. i.e. use the full form "do not" rather than the contracted form "don't".