The effect of high charge rate on performance and degradation of ZEBRA cells was investigated. The cells were cycled using a 1C (38 A) charge current and a more lenient C/3 discharge rate. It is found that the ZEBRA cells are prone to quickly developing imbalances among the cells connected in series. The cathode and solid electrolyte of cycled cells were investigated by optical microscopy, scanning electron microscopy, energy dispersive spectroscopy and X-ray diffraction. Microstructural changes associated with the developed imbalances are discussed. (C) 2016 The Electrochemical Society. All rights reserved.