Lack of airflow may cause your computer to run at higher temperature.
Even if this does not exceed the laptop's specifications,
you could still be shortening your battery life.
In addition, as far as I can see, the battery on this model is not easily replaceable
and you’ll probably void your warranty by doing so.
This is taken from the article How to Prolong Lithium-based Batteries :
As the laptop will most probably be connected to the mains while its lid is closed,
battery charge will probably remain at 100%, where temperature highs have maximum effect.