4,4′-Biphenyldicarboxylic acid as an anode for sodium-ion batteries: Different electrochemical behaviors in ester and ether-based electrolytes

Organic electrode materials have been regarded as sustainable alternatives for sodium-ion batteries (SIBs) due to their high theoretical specific capacity, large reserves and wide sources from biomass. However, the variety of presently reported organic electrode materials is very limited and their essential electrochemical sodium storage behaviors also deserve further investigating. In this paper, we explore the electrochemical sodium storage behavior of a conjugated aromatic acid (4,4′-biphenyldicarboxylic acid, H₂bpdc) in esters and ethers-based electrolytes. The results illustrate that in esters-based electrolytes, H₂bpdc just shows limited capacity and poor electrochemical sodium storage kinetics. By contrast, in ethers-based electrolytes, H₂bpdc experiences a process similar to conversion type mechanism from pristine acid to sodium salt, displaying fast kinetics and delivers a high reversible capacity of 280 mA h g⁻¹. This research would provide basic and novel insights to the electrochemical sodium storage behaviors of promising organic electrode materials and accelerate the new materials exploration process for SIBs.