Electronic air cleaners for use in heating, air-conditioning, and ventilation (HVAC) systems and associated methods and systems are disclosed herein. In one embodiment, an electronic air cleaner includes one or more collecting electrodes having a collection material with a porous, open-cell structure and a conductive internal portion. The collection material can be configured to collect and receive charged particulate matter in an airflow path. After a period of time, used collection material can be removed from individual collecting electrodes and replaced with new collection material.