  We propose a cavity-Heisenberg spin chain (CHS) quantum battery (QB) with the
long-range interactions and investigate its charging process. The performance
of the CHS QB is substantially improved compared to the Heisenberg spin chain
(HS) QB. When the number of spins $N \gg 1$, the quantum advantage $\alpha$ of
the QB's maximum charging power can be obtained, which approximately satisfies
a superlinear scaling relation $P_{max} \propto N^{\alpha}$. For the CHS QB,
$\alpha$ can reach and even exceed $1.5$, while the HS QB can only reach about
$\alpha=0.75$. We find that the maximum stored energy of the CHS QB has a
critical phenomenon. By analyzing the Wigner function, von Neumann entropy, and
logarithmic negativity, we demonstrate that entanglement can be a necessary
ingredient for QB to store more energy, but not sufficient.
