I think, though I’m not certain, that this letter to the journal Nature is accessible without a subscription. The author, Mikhail Gelfand, is responding to a remark in an earlier issue that Russian had the largest alphabet of any language, and points out that several of the languages of the Caucasus have still larger ones.
“The outright winner is the Archi alphabet, developed in 2006. This is another language from the Caucasus and has 97 letters — although many of these are groups of two, three or even four or five characters, rather than independent signs. The highest number of independent signs, at 41, is probably to be found in Abkhaz.”