Polymer-based solid/semi-solid electrolytes in lithium ion batteries

The inception of lithium-ion batteries with liquid electrolytes can be traced back to the early 1980s. Nevertheless, the utilization of liquid electrolytes has many drawbacks, including its susceptibility to combustion, limited energy density, and very brief operational lifespan. Consequently, there is currently a concerted effort to substitute liquid electrolytes with solid compounds. This study investigates the electrochemical and mechanical features of solid/semi-solid electrolytes used in lithium ion batteries (LIBs) as well as their performance relative to conventional liquid electrolytes, with LIBs having unique challenges related to high flammability, electrochemical instability, and low mechanical stability posed by conventional liquid electrolytes versus solid polymer electrolytes (SPEs) which provide greater safety, mechanical stability but lower ionic conductivity than liquid counterparts. SPEs offer better safety but lack sufficient ionic conductivity which limits their potential. In order to overcome these obstacles, the implementation of gel-based and composite solid and semi-solid electrolytes is proposed as a means to improve ionic conductivity, electrochemical stability, and mechanical stability. The study suggests that a focus should be placed on solid composite electrolytes as they possess higher mechanical stability, which contributes to improved safety. Additionally, these electrolytes exhibit enhanced ionic conductivity within the range of 10 −4 to 10 −2 S/cm, hence enhancing the performance of LIBs.