In certain phase-transforming electrodes for Li-ion batteries, the voltage hysteresis between charge and discharge is observed to remain finite even as the charging/discharging current goes to zero. In this paper, using both sharp-interface and Cahn-Hilliard models, we show how pinning of a phase boundary by heterogeneities within an electrode particle leads to zero-current hysteresis. The theory predicts zero-current hysteresis even for a single particle. More broadly, we study the role of heterogeneities in phase-transforming electrodes and show how they lead to interesting behavior such as nonunique OCV, fluctuating interface propagation, and multiple nucleation sites. (C) 2017 The Electrochemical Society. All rights reserved. All rights reserved.