Lithium ion conducting membrane based on K-carrageenan complexed with lithium bromide and its electrochemical applications

Lithium conducting materials play a major role in developing electrochemical devices. Green materials have gained much attention in order to face an energy crisis and global warming. Many researchers took effort to develop biopolymer electrolyte-based electrochemical devices instead of the synthetic polymer due to its high cost and not being environmentally green. K-carrageenan membranes with different concentrations of lithium bromide (LiBr) have been prepared by a solution casting technique and characterized by XRD, FTIR, DSC, and AC impedance technique. One gram of K-carrageenan with 0.5 wt% of LiBr has the highest conductivity as 3.43 × 10−3 Scm−1 at room temperature, and it has high amorphous nature as per the powder XRD results. FTIR confirms the complex formation between LiBr and K-carrageenan. The shift in glass transition temperature (Tg) of the membrane is observed from the DSC. The highest-conducting polymer electrolyte has a glass transition temperature of 44.55 °C. The DC polarization technique proves that the conductivity is due to ions. Lithium ion–conducting battery has been constructed using the highest-conducting biopolymer electrolyte membrane, and its output voltage is measured.