Metal based batteries that comprise of a reactive metal anode like lithium, sodium or potassium are the future of energy storage devices because of their high volumetric and gravimetric energy density. However, these batteries fail by three distinct modes – chemical instability due to internal reactions, morphological instability due to uneven electrodeposition and hydrodynamic instability due to convective flows at the vicinity of electrode-electrolyte interface. Both liquid based, and solid-state electrolytes have their individual advantages and disadvantages in mitigating these issues. In this work, we show that solid-polymer interphases based on crosslinked polymer networks can essentially possess qualities from both of these worlds. We find that by tuning the thermodynamic interactions between the polymer network and oligomer diluents, one can control the bulk properties like ion transport and mass transfer rate. Thus, it is possible to design solid-like electrolyte-phases where the electroconvective flows can be inhibited, while maintaining high ionic conductivity. We further show that these polymer networks act as excellent interfacial layer for lithium metal electrode to inhibit dendrite growth and side reactions. On pairing with high voltage cathodes, the lithium metal battery exhibit over 250 cycles of stable operation even at high current densities.