I'm not an expert, but my understanding is that silicon really loves to be with lithium, which makes it a really energy-dense anode material for batteries. It's also cheap and abundant. The problem is that absorbing lithium causes silicon to mechanically expand, which quickly destroys cell life. The anode physically crumbles away with repeated charging and discharging.<p>These researchers have found a way to make a silicon electrode like a sponge, which helps with the mechanical problems. Their test cell has pretty "normal" degradation of 80% capacity retention over 1700 cycles, which is incredibly good for silicon. Normally it would be in the 10's or 100's, iirc.