Separator with a ceramic-comprising separator layer

A battery cell assembly, comprising:

• a first electrode;
• a second electrode;
• and
• a separator between the first electrode and the second electrode;
• wherein:
• the separator comprises a first layer comprising metal oxide, metal hydroxide, or metal oxyhydroxide particles, the first layer being directly deposited on the first electrode via casting or spray-drying;
• a thickness of the separator ranges between about 0.5 μm to about 10 μm;
• the metal oxide, the metal hydroxide, or the metal oxyhydroxide particles comprise (1) fiber-shaped particles characterized by diameters in a range from around 3 nm to around 2 microns and aspect ratios in a range from around 4 to around 1,000,000 and (2) non-fiber shaped particles;
• and
• the separator exhibits a pore exclusion size in a range from about 10 nm to about 1 μm.