The study of electrolyte reactivity on electrode materials is fundamental to understand the service life of lithium ion batteries (LIBs). In this paper, a new type of symmetric cells, termed double half-cells (DHC), has been designed to evaluate electrolyte reactivity precisely and accurately while only using a standard charger. The construction of DHCs avoids the disassembly/assembly process and electrode alignment issues associated with conventional symmetric cells, resulting in improved performance and reliability. Using DHCs, electrolyte reactivity on graphite and copper were investigated. While electrolyte reactivity on Cu and graphite were found to be low at room temperature, elevated temperatures resulted in significant electrolyte reactivity on both surfaces. The addition of vinylene carbonate to the electrolyte was found to have little effect on graphite electrodes, but results in severe electrolyte decomposition on copper. These results show the utility of DHCs and also that inactive materials, such as current collectors, should not be ignored when considering electrolyte decomposition reactions in Li-ion cells. (C) 2017 The Electrochemical Society. All rights reserved.