The difficulty with silicon is that it has expansion properties...

The difficulty with silicon is that it has expansion properties that are like water to ice expansion on steroids. It doesn't just expand 9% like water does as it freezes, but its expansion is over 100% (some articles reference up to 300%). This is a physical/chemical characteristic so its not going to go away so the question is whether it can be managed. No cost-effective mechanism has emerged and quite frankly given the challenge, none is likely to emerge. This change in volume issue means any high silicon content battery is creates the risk of cracking/breaking the battery structure. You might be able to create the battery, but a reliable long cycle life is the problem. Even if managed, even the smallest manufacturing issue could over-time cause the battery to fail. If you can't guarantee the product for a sensible minimum life, you don't have a commercial product to sell to consumers.

Among the best solutions found so far for premium batteries is an anode product involving silicon coated graphite. Most of the product by volume is still spherical graphite but there's a thin silicon coating and that increases the ability to store electrical charges. By getting even 5-10% silicon into the product you get a piece of its much better electrical storage but the expansion issue is limited enough that it doesn't break the battery apart. Its not an either one or the other situation, but a blended combination.

DYOR but that's my understanding.