Gradually activated lithium uptake in sodium citrate toward high-capacity organic anode for lithium-ion batteries

Lithium-ion batteries (LIBs) have been used to power various electric devices and store energy, but their toxic components by using inorganic materials generally cause serious environmental issues when disused. Recently, environmentally friendly and naturally abundant organic compounds have been adopted as promising electrode materials for next-generation LIBs. Herein, a new organic anode electrode based on sodium citrate is proposed, which shows gradually activated electrochemical behavior and delivers a high reversible capacity of 776.8 mAh·g⁻¹ after 1770 cycles at a current density of 2 A·g⁻¹. With the aid of the electrochemical characterization, Fourier-transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS) analysis, the lithium uptake mechanism of sodium citrate-based anodes is identified to be a combination of three-electron lithiation/delithiation and fast Li⁺ intercalation/deintercalation processes, in which Faradaic reactions could offer a theoretical contribution of 312 mAh·g⁻¹ and intercalation pseudocapacitance would provide extra capacity. This work demonstrates the great potential for developing high-capacity organic electrodes for LIBs in future.