Neutral polymer electrolytes using LiCl-Polyacrylamide (PAM) was developed. LiCl-PAM has achieved a good ionic conductivity > 10 mS cm− 1 in ambient environment. The LiCl-PAM enabled solid CNT-graphite supercapacitor has a 1.5 V stability window. The solid cell showed excellent rate performance (5 V s− 1) and cycle life (10,000 ×).