We came across a post in Tech Briefs we link to below, because we found their discussion important and illuminating. In a nut shell, what they are saying is liquid-electrolyte batteries are flexible, and can withstand stresses and strains. Whereas, the mechanical forces inside solid-state batteries may exert considerable stress, and even damage solid-state batteries permanently.
Why Discuss Solid-State Mechanical Battery Forces Now?
Tech Briefs makes a good case for a disconnect existing between battery electro-chemical, and mechanical sciences. And as a result, we may have been over-preoccupied with explaining how battery chemistry works.
Their writer suggests we should also view a battery as a mechanical system to obtain the full picture. When we do so, we discover the mechanical forces inside solid-state batteries create stresses during charging and recharging, leading to dendrites.
Now we do know, of course that these forces have their influence inside liquid-electrolyte batteries too. That’s because they may fracture electrode particles, and reduce their active areas. However, in this case Tech Briefs explains the electrode fragments remain in contact with the fluid, liquid electrolyte.
But Solid-State Electrode Particles Behave Differently
As we read through the report, we are reminded that solid-state electrolyte cannot flow around electrode particles. And that these fractures therefore lead to capacity loss, or the reduced ability of the battery to convert ionic flows into electronic current, and ultimately electricity.
Lithium dendrites are a case in point. They are able to fracture solid electrolytes, reach through gaps to the other side, and cause short circuits. When we view this from a mechanical perspective, we realize how soft lithium metal becomes very hard, in a tightly confined space within microscale pores.
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