A dense cellulose-based membrane as a renewable host for gel polymer electrolyte of lithium ion batteries

A dense instead of porous gel polymer electrolyte for lithium ion batteries is reported for the first time. Its host is a renewable and environment friendly polymer, hydroxyethyl cellulose (HEC). The preparation of HEC membrane is very simple. The membrane is stable up to 280°C, much higher than the melting points of those commercial separators based on polyolefin. The evaporation temperature of the organic electrolyte in the prepared gel polymer electrolytes is up to 75°C. In addition, the gel polymer electrolyte shows good electrochemical performance including high ionic conductivity at room temperature, and a high lithium ion transference number. When tested as separator and electrolyte, a LiFePO₄ positive electrode displays satisfactory electrochemical properties including high discharge capacity and stable cycling. These results indicate a very promising direction for a low cost and renewable gel polymer electrolyte for lithium ion batteries.