The effect of different surfactants as electrolyte additives on NaTi2(PO4)3/C anode

Abstract

Aqueous rechargeable batteries have attracted attention because of their low cost and high security, but the electrode materials have poor cycling stability in aqueous electrolytes. In this paper, different surfactants (sodium dodecyl sulfate, SDS; sodium laurylsulfonate, SLS; carboxymethyl cellulose sodium, SCC; hexadecyl trimethyl ammonium bromide, CTAB; poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol), F127) were used as additives to the electrolyte (0.5 M Na2SO4 aqueous solution). The effect of surfactant additives on the electrochemical parameters such as the conductivity, diffusion coefficient (DNa), transfer coefficient (α), and self-corrosion current (icorr) of NaTi2(PO4)3/C was characterized by cyclic voltammetry, galvanostatic charging/discharging, electrochemical impedance spectroscopy, and Tafel polarization tests. It is found that the addition of surfactant reduced the capacity decay of NaTi2(PO4)3/C anode and improved its capacity retention rate, especially SDS, which was 81.2% after 100 cycles. Possible reasons were analyzed as follows: (1) surfactants inhibited the decomposition of water in the electrolyte and (2) surfactants adsorbed on the surface of NaTi2(PO4)3/C reduced its contact with H2O molecules and relieved the dissolution of NaTi2(PO4)3/C.