Tea polyphenols as a novel reaction-type electrolyte additive in lithium-ion batteries

Abstract

In this study, we reported tea polyphenols (TP) as a novel, cheap, environment-friendly and easy dissolution in common electrolytes reaction-type electrolyte additive for the graphite anode of the lithium-ion batteries. The TP can capture less stable radical anions that are harmful to oxidation stability of ethylene carbonate (EC) to form stable polymer. To a certain extent, it improved the electrochemical performance of the graphite electrode such as reversible capacity and cyclic stability by charge-discharge test, cyclic voltammetry (CV), scanning electron microscope (SEM), and electrochemical impedance microscope (EIS). The first charge capacities of the graphite electrodes in electrolytes without and with TP were 327.1 and 349.1 mAh g−1, respectively. The charge capacities were 306.8 and 344.2 mAh g−1 after 100 cycles and the capacity retention were 93.79 and 98.60%, respectively. The improvement was benefited from the effective scavenging the less stable radical anions and improvement the oxidation stability of EC and formation of a stable, compact and thin solid electrolyte interface (SEI) film with lower resistance.