Name and explain one recent layer-2 innovation that addresses the scalability problem associated with proof-of-work-based blockchains.

The invention of Proof-of-stake addresses the scalability problem. By randomly addressing transactions to stakers which become validators, way less computational power is needed, hence, the need for large polluting mining pool decreases. In addition, for instance the Beacon chain, creates extra layers on the blockchain, facilitating more scalability.