MnCO 3 Cuboids from Spent LIBs: A New Age Displacement Anode to Build High-Performance Li-Ion Capacitors.

The advantage of hybridizing battery and supercapacitor electrodes has succeeded recently in designing hybrid charge storage systems such as lithium-ion capacitors (LICs) with the benefits of higher energy than supercapacitors and more power density than batteries. However, sluggish Li-ion diffusion of battery anode is one of the main barriers and hampers the development of high-performance LICs. Herein, is introduced a new conversion/displacement type anode, MnCO 3 , via effectively recycling spent Li-ion batteries cathodes for LICs applications. The MnCO 3  cuboids are regenerated from the spent LiMn 2 O 4  cathodes by organic acid lixiviation process, and hydrothermal treatment displays excellent reversibility of 535  mAh g -1  after 50  cycles with a Coulombic efficiency of >99%. Later, LIC is assembled with the regenerated MnCO 3  cubes in pre-lithiated form (Mn 0  + Li 2 CO 3 ) as anode and commercial activated carbon (AC) as the cathode, delivering a maximum energy density of 169.4 Wh kg -1  at 25 °C with ultra-long durability of 15,000 cycles. Even at various atmospheres like -5 and 50 °C, this LIC can offer a energy densities of 53.8 and 119.5 Wh kg -1 , respectively. Remarkably, the constructed AC/Mn 0  + Li 2 CO 3 -based LIC exhibits a good cycling performance for a continuous 1000 cycles with >91% retention invariably for all temperature conditions.