In　this　paper,　a　novel　transformer-less　bidirectional　DC-DC　topology　with　wide　voltage　conversion　range　is　proposed　for　energy　storage　systems.　The　novel　topology　is　constituted　of　one　inductor,　two　capacitors,　two　active　power　switches,　and　two　synchronous　rectifiers.　It　achieves　wider　conversion　range　and　lower　power　electronic　devices　voltage　stress　than　the　conventional　buck-boost　topology　without　using　extreme　duty　ratio.　The　control　strategy　is　easy　for　the　simple　structure　of　the　new　topology.　The　steady-state　theoretical　analysis　and　operating　principles　of　the　topology　are　explained　in　detail.　Besides,　the　voltage　stress　and　current　stresses　of　switches　are　analyzed.　Finally,　in　order　to　verify　the　feasibility　of　the　topology,　a　12-48V/48-12V　model　was　built　in　MATLAB　and　pave　the　way　for　subsequent　experimental　verification.　©　2021　IEEE.