Synthesis, characteristics, and electrochemical performance of N,N-(p-phenylene)bismaleamate and its fluorosubstitution compound on organic anode materials in lithium-ion batteries

Abstract

Conventional lithium-ion batteries (LIBs) comprise lithium transition metal oxide as a cathode and graphite as an anode. Because of global climate change, growth in the electric vehicle industry, carbon reduction policies, and high energy density requirements, several graphite replacements for LIBs, such as metalloid and organic compounds, have been studied. However, metalloids cause substantial problems when alloys with lithium ions, including volume expansion and electrochemical irreversibility. Organic compounds also have drawbacks, such as low electronic conductivity and low thermal stability. In this study, bismaleamate and its fluorosubstitution polymer are synthesized and evaluated to prevent the aforementioned problems. Calculations of electrochemical performance indicate that the bismaleamate fluorosubstitution significantly reduced the energy band gap to approximately 0.02 eV, and the battery had a capacity of 430.0 mAh g−1 after 350 cycles. The rate performance is significantly improved because of the low energy band gap when the battery operated at 10 C/10 C (190 mAh g−1). The Brunauer–Emmett–Teller analysis indicates that the bismaleamate fluorosubstitution had four times the surface area and 10 times the pore size of bare bismaleamate. The fluorosubstitution produced an obvious three-dimensional steric effect and an asymmetrical structure, which facilitates excellent ionic transfer. X-ray photoelectron spectroscopy revealed that the weak electron-acceptance effect of the fluorosubstitution considerably inhibites solid electrolyte interphase formation and deliveres a notable reaction mechanism for its structure rearrangement. Operando X-ray diffraction patterns confirme changes in the crystal phase of the two bismaleamates. As new organic anode materials, bismaleamates have demonstraed excellent performance in terms of battery capacity, rate, and life cycle. Therefore, bismaleamates have potential applications in lithium-ion and beyond-lithium secondary batteries.