Multi-Ions Electrolyte Enabled High Performance Voltage Tailorable Room-Temperature Ca-Metal Batteries

Calcium metal batteries, as one of the promising alternatives beyond Li-metal technology, is held back by the lack of suitable cathodes of considerable energy storage capability, and Ca anodes of long-term stability and lower polarization potentials for Ca-plating/stripping. Here, by recycling cellulose waste paper, feasible cathodes for Ca-metal batteries of good high-voltage and wide-window-voltage adaptability (0.005-4.9 V versus Ca/Ca2+), and impressive energy density (approximate to 517.5 Wh kg(-1) at 0.1 A g(-1)) are developed. Meanwhile, through tailorable Ca-plating/stripping potentials ( increment V approximate to 0.65 V) realized by a modified electrolyte of Li+, Ca2+, BF4-, and PF6- multi-ions system, the proof-of-concept Ca-metal batteries not only delivered enhanced storage capability (101 mAh g(-1) versus 51 mAh g(-1) at 0.1 A g(-1) in the window voltage of 2.0-4.7 V) and cycling stability (approximate to 77% capacity retention for 100 cycles), but also simultaneously show a high output average working voltage of approximate to 3.2 V. The work provides a hint that mixed metal deposition under multi-ions electrolyte system may address the challenging issues faced by single alkali or alkaline-earth metal batteries.

Automated summary

By recycling cellulose waste paper, feasible high-voltage and wide-window-voltage adaptable cathodes for calcium metal batteries are developed, along with proof-of-concept batteries showing enhanced storage capability and cycling stability through a modified electrolyte system. This work hints that mixed metal deposition under a multi-ion electrolyte system may help solve challenging issues faced by single alkali or alkaline-earth metal batteries.