According to the Van Dale, 'accu' is used in Belgium: http://vandale.nl/opzoeken?pattern=batterij&lang=nn
But according to my partner (who's Flemish), accu is rarely used because it's very old fashioned, and in any case, it'd be only used when referring to a car battery.
(By the way, accu comes from accumulator)
The bilingual version doesn't say whether there's a difference or not: http://vandale.nl/opzoeken?pattern=battery&lang=en
Ngram viewer: http://kbresearch.nl/dbnl/ngram-viewer/
The Ngram viewer seems to confirm what my partner told me.