Paleolithic body paint and perhaps in ritual. Undisputed evidence of art only becomes common in the Upper Paleolithic. Lower Paleolithic Acheulean tool users, according to Robert G. Bednarik, began to engage in symbolic behavior such as art around 850,000 BP. They decorated themselves with beads and collected exotic stones for aesthetic, rather than utilitarian qualities. According to him, traces of the pigment ochre from late Lower Paleolithic Acheulean archaeological sites suggests that Acheulean societies, like later Upper Paleolithic societies, collected and used ochre to create rock art. Nevertheless, it is also possible that the ochre traces found at Lower Paleolithic sites
Research in lithium-ion batteries and heating that can ignite the flammable electrolyte. Lithium metal remains a subject of interest because of its potential to increased energy density by 2x or more. In 2015, an MIT spinoff company, SolidEnergy, demonstrated a battery that uses a thin sheet of lithium-metal foil. The company claimed to have solved multiple issues, including safety and lifetime. SolidEnergy uses a combination of solid and liquid electrolytes. The solid electrolyte is applied to the lithium-metal foil—the ions don’t have far to travel through this thin material, so it does not matter that they move relatively slowly. Once through the solid electrolyte,