Dual‐Graphite Batteries with Flame‐Retardant Electrolyte Solutions

Although trimethyl phosphate (TMP)‐based electrolyte solutions are effective to resist flames in non‐aqueous electrical energy storage devices, they are usually not so compatible with Li‐graphite negative electrodes. Herein, we solve this problem by increasing the concentration of LiPF6 salt in the solution. A benchmark graphite negative electrode (MCMB, mesocarbon microbeads) can deliver a capacity over 325 mAh g−1 and maintain good cyclability in a solution of 3 M LiPF6‐ethyl methyl carbonate (EMC)/TMP (7 : 3 by vol.). Moreover, our previous work has confirmed that the graphite positive electrode also works very well in the above solution. Therefore, this solution can cater to both anion‐graphite and Li‐graphite intercalation electrodes, which enables the construction of dual‐graphite batteries (DGBs). There are some problems arising during the DGB operation, and corresponding strategies are proposed.