The emergence of solid-state batteries caused a sharp drop in the stock prices of companies related to battery separators. So, what role does the separator play in a battery? Why did the appearance of solid-state batteries lead to a decline in the stock prices of battery separator companies?
In liquid lithium-ion batteries, the separator is one of the four key materials. The performance of the separator determines the battery's interface structure, internal resistance, etc., and directly affects the battery's capacity, cycle life, and safety performance. A high-performance separator plays an important role in improving the overall performance of the battery.
The separator separates the positive and negative electrodes of the battery, preventing them from coming into contact and short-circuiting. It also allows electrolyte ions to pass through. Furthermore, since the electrolyte is an organic solvent, the separator must also be resistant to organic solvents.
The similarities between liquid lithium-ion batteries and solid-state batteries are that they use the same positive and negative electrode materials. The positive electrode materials can be divided into lithium cobalt oxide, lithium manganese oxide, ternary materials and lithium iron phosphate materials, while the negative electrode is graphite. The working principle of the batteries is also basically the same.
One point to note is that the main difference between liquid lithium-ion batteries and solid-state batteries lies in the electrolyte. Liquid lithium-ion batteries use a liquid electrolyte, while solid-state batteries use a solid polymer electrolyte. This polymer can be in a "dry" state or a "gel" state, and currently most use polymer gel electrolytes.
Solid polymer electrolytes can function as both electrolytes and separators, therefore, in true solid-state batteries, electrolytes and separators are no longer needed. This is the primary reason why the stocks of electrolyte and separator companies plummeted after the news of solid-state batteries broke.
