One with a fluid electrolyte. That includes current Lithium-Ion and Lithium-Polymer batteries, as well as the older Nickle-Metal Hydride and Lead-Acid batteries.
A lithium-ion battery is composed of cathode, anode, separator and electrolyte. Lithium-ion batteries for smartphones, power tools and EVs uses liquid electrolyte solution. On the other hand, a solid-state battery uses solid electrolyte, not liquid.
Liquid in the scientific sense, it's more of a paste. Lithium hexafluorophosphate(aka LiFPO) mixed with Dimethyl carbonate or Diethyl carbonate which are just there to float the Lithium between the plates without letting it burst into flame from any humidity that might happen to reach in.