In order to support wider use of distributed renewable sources and mitigate the negative effects of their intermittent behavior, nowadays they are often installed together with energy storages, located on-site or nearby. Battery energy storage systems (BESS) allow not only to match consumption and generation profiles more closely, but also they provide various ancillary grid-supporting services. The enabling technology for these emerging opportunities is related to power electronic interfaces between the DC battery and the AC grid. Generally, a two-stage power conversion approach is used, where the battery-side DC-DC stage is responsible for controlling the battery current and grid-side DC-AC stage controls the current taken or injected to the grid. These two stages are connected through a bulky DC-link capacitor with stabilized voltage. Such an approach has however reached its limits in terms of efficiency, power density and cost. Therefore, a lot of research is currently focused on alternative topologies, enabling higher performances than the well-developed two stages approach. One of the promising configurations of such alternative topology includes a DC-DC converter, that forms sine voltage half-waves and an unfolding circuit, which provides the commutation of these half-waves to the grid. This paper presents a review of unfolding converters in the context of BESS. Configurations of unfolding circuits with DC-DC choppers, dual active bridge converters and multilevel converters, as well as the partial power converters are analyzed.