  We demonstrate that photoacoustic microscopy (PAM) can be a potential novel
imaging tool to investigate the Li metal dendrite growth, a critical issue
leading to short circuit and even explosion of Li metal batteries. Our results
suggest several advantages of PAM imaging of Li metal batteries: high
resolution (micrometers), 3D imaging capability, deep penetration in a
separator, and high contrast from bulk Li metal. Further, PAM has potential for
in situ real-time imaging of Li metal batteries.
