  We study maximal bipartite entanglement in valence-bond states and show that
the average bipartite entanglement $E_v^2$, between a sub-system of two spins
and the rest of the system, can be maximized through a homogenized
superposition of the valence-bond states. Our derived maximal $E_v^2$ rapidly
increases with system size and saturates at its maximum allowed value. We also
demonstrate that our maximal $E^2_v$ states are ground states of an infinite
range Heisenberg model (IRHM) and represent a new class of
resonating-valence-bond (RVB) states. The entangled RVB states produced from
our IRHM are robust against interaction of spins with both local and global
phonons and represent a new class of decoherence free states.
