Solid State Batteries will be the successor to Lithium ion Batteries

Toyota has long clung to the Nickel-Metal-Hydride (NiMH) batteries, claiming that lithium-ion batteries are too expensive. Toyota is looking to solid state and lithium-air batteries. By modifying liquefied electrolytes into solid electrolytes, it allows each cells to connect without the need for individual casing, which results in creating a more compact packaging. Solid state batteries could thus have one fifth the volume of current batteries. What makes that possible is the use of solid electrolytes. Rather than a liquid sloshing around, a solid state battery has blocks of solid material pressed together. This requires less packaging to achieve the same effect as the liquid electrolyte batteries.

With metal-air batteries, the cathode is "air", meaning that the battery weight is only the anode. The problem with this picture is that with current lithium-air battery research, the "air" must be pure oxygen, and cannot be any old air from the atmosphere. This is because of contaminants and especially humidity. Lithium-metal burns in certain conditions. To resolve this problem lithium-air battery researchers have gizmos to extract pure oxygen from the atmosphere to provide the proper stuff to the lithium-air battery. That gizmo adds to the packaging complexity of lithium-air batteries in a way that is not shown on Toyota's picture.

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