Pi Network claims to be the only cryptocurrency you can mine on your phone. It uses the Stellar Consensus Protocol (SCP), in which each node only validates other nodes it trusts. Pi claims its algorithm only uses lightweight messages to determine mining consensus, which can be done on mobile phones with low cost and limited battery drain.
Is there any other project that enables mining on mobile phones, or is Pi Network the first?
If you want to try Pi out, you can join here (by invite only, using my ID BlockchainAlchemist).