A Nonflammable Na+-Based Dual-Carbon Battery with Low-Cost, High Voltage, and Long Cycle Life

Dual-carbon batteries provide a new perspective on energy storage technology due to their high voltage and low cost. Herein, a novel Na+-based dual-carbon battery (Na+-DCB) is developed based on a nonflammable trimethyl phosphate (TMP) electrolyte with sodium bis(trifluoromethanesulfonate)imide salt (NaTFSI). As the molar ratio of NaTFSI/TMP increases to 1:2, the graphite cathode shows a high reversible capacity of 52.9 mAh g(-1), excellent rate capability (21.0 mAh g(-1) at 2000 mA g(-1)) and superstability cycling performance (approximate to 100% capacity retention after 750 cycles). In addition, a stable solid electrolyte interface (SEI) film is formed on the surface of hard carbon anode by the preferential reductive decomposition of TFSI-, which suppresses decomposition of TMP. In this case, the Na+-DCB is capable to provide an operation voltage of 4.0 V and excellent electrochemical performance. This work provides new insights for developing new dual-carbon batteries with safety, low cost, and absence of heavy metals.