there is no need to convert the filenames already when creating the gz-files. Do
for %i in (*.html) do 7z a -tgzip "gz\%i" "%i"
then change to the gz sub-directory and do
7z a -tzip -mcu=on dicthtml.zip *.html words
If the location of 7z.exe is not known to the system give the full path, for instance "C:\Program Files\7-Zip\7z" (including the quotation marks).