Investigation the Effect of DMMP as Electrolyte Additive on the Flammability and Electrochemical Properties of Lithium-Ion Batteries

Dimethyl methyl Phosphonate (DMMP) was used as a flame retardant to reduce the flammability of the electrolyte with minimum negative impact on the electrochemical performance of the electrodes. The flammability and thermal stability of prepared electrolyte in the presence of DMMP by different contents were evaluated using self-extinguishing time (SET), differential scanning calorimeter (DSC). Linear Sweep voltammetry (LSV) and galvanostatic charge and discharge tests were carried out to investigate the effect of DMMP on the electrochemical properties. When a sample containing 5 vol.% DMMP is used as electrolyte in 18650 cell, the cell exhibits quite good cycling stability; like the Blank electrolyte with capacity fade after 55 cycles at 0.1 C is 92.68 and 96.59%, respectively. The cathode electrode interface is characterized with EIS, SEM, and XRD, DSC after several charge/discharge cycles which demonstrate stable and liner protective film is formed on the surface of cathodes in the presence of 5 vol.% DMMP. The results imply that DMMP is a promising option as highly flame-retardant and electrochemically compatible electrolyte additive for safe lithium-ion batteries