In conventional electronics, mobile and charged electrons or holes are information carriers that deliver data throughout media. Spin-electronics or Spintronics rely on accurate manipulation of spin states and spin transport by angular momentum carriers. I will discuss our recent progress in better understanding of angular momentum transport in experimentally relevant structure. Three spin batteries that drive spin angular momentum flow are proposed and the resulting spin currents in several layered structure are investigated. Particular focus will be placed on the conversion between conduction electron spin current and magnon current at the interface of a non-magnetic metal and a magnetic insulator. Among other things, we predict magnon mediated spin information propagation in magnetic insulators.