Since x (and consequently y1 and y2) are column vectors, using fliplr does not have the desired effect. Instead you can use flipud or the more general flip. And use vertical concatentation (i.e., [x; flip(x)]) rather than horizontal concatenation (i.e., [x flip(x)]).
close
x = (0:60)';
y1 = 0.5025*exp(0.0471*x); y2=0.2045*exp(0.02*x);
hold all
plot(x,y1)
plot(x,y2)
patch([x; flip(x)], [y1; flip(y2)], 'c','EdgeColor','none', 'FaceAlpha',0.25)
