A High-Performance Rechargeable Mg²⁺/Li⁺ Hybrid Battery Using One-Dimensional Mesoporous TiO₂(B) Nanoflakes as the Cathode

Mg(2+)/Li(+) hybrid batteries have recently been constructed combining a Mg anode, a Li(+)-intercalation electrode, and an electrolyte containing both Mg(2+) and Li(+). These batteries have been reported to outperform all the previously reported magnesium batteries in terms of specific capacity, cycling stability, and rate capability. Herein, we report the outstanding electrochemical performance of Mg(2+)/Li(+) hybrid batteries consisting of a one-dimensional mesoporous TiO2(B) cathode, a Mg anode, and an electrolyte consisting of 0.5 mol L(-1) Mg(BH4)2 + 1.5 mol L(-1) LiBH4 in tetraglyme. A highly synergetic interaction between Li(+) and Mg(2+) ions toward the pseudo-capacitive reaction is proposed. The hybrid batteries show superior rate performance with 130 mAh g(-1) at 1 C and 115 mAh g(-1) at 2 C, together with excellent cyclability up to 6000 cycles.