Lighter, more powerful batteries

Despite recent breakthroughs in carbon-based batteries, lithium-ion cells will remain the standard for years to come. Lucky, then, that University of Michigan researchers have found a way to cut lithium-ion batteries’ weight – one of the biggest range limitations for electric vehicles – while extending their lives.

The team was trying to solve the “dendrite problem” – microscopic lithium filaments that sprout like fungus on one electrode and relentlessly creep across the battery toward the other. Dendrites can short-circuit power production, reduce battery life and even cause fires.

The team solved the problem by weaving strands of aramid into sheets with pores big enough to let lithium ions flow from one electrode to the other, but small enough to foil dendrite spread. Aramid is a feather-light, nylon-like fiber that’s a key element of Kevlar, the main fabric in bulletproof vests. 

The discovery means that batteries can pack more power, and less weight, in the same-sized case. Or, they can deliver the same amount of power in a smaller, lighter package – a factor that could change electric-vehicle design. 

The university has spun off Elegus Technologies, a company that will commercialize aramid sheets next year.

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