(Ⅰ)因为2Sn=3an-1,
所以2Sn-1=3an-1-1,(n≥2)
两式相减得2an=3an-3an-1,
所以 an=3an-1,
所以数列{an}是等比数列的公比q=3
当n=1,得2a1=3a1-1,解得a1=1.
则an=3n-1.
(Ⅱ) bn=an+(-1)nlog3an=3n-1+(-1)nlog33n-1=3n-1+(-1)n(n-1),
则数列{bn}的前2n项和T2n=(1+3+32+…+32n-1)+[-0+1-2+3-…+(2n-1)]=
+n=1?32n
1?3
+n?32n 2
.1 2