Ambient Pressure Relithiation of Degraded Li x Ni 0.5 Co 0.2 Mn 0.3 O 2 (0 x 1) via Eutectic Solutions for Direct Regeneration of Lithium Ion Battery Cathodes
DOI: 10.1002/aenm.201900454 Today's lithium ion batteries (LIBs) can offer high energy density (260 Wh kg 1 and 700 Wh L 1 at cell level) and high Coulombic efficiency (99.98% and long cycling life >1000 cycles) making them the dominating power sources for portable electronics and electric vehicles (EVs)[1,2] Due to With the rapid growth of the lithium ion battery (LIBs) market, recycling and re use of end of life LIBs to reclaim lithium (Li) and transition metal (TM) resources (e.g. Co, Ni) as well as eliminating pollution from disposal of waste batteries, has become an urgent task. Here, for the first time the ambient pressure relithiation of degraded LiNi0.5Co0.2Mn0.3O2 (NCM523) cathodes via eutectic Li+ molten salt solutions is successfully demonstrated. Combining such a low temperature relithiation process with a well designed thermal annealing step, NCM523 cathode particles with significant Li loss (40% and capacity degradation (50% can be successfully regenerated to achieve their original composition and crystal structures, leading to effective recovery of their capacity, cycling stability, and rate capability to the levels of the pristine materials. Advanced characterization tools including atomic resolution electron microscopy imaging and electron energy loss spectroscopy are combined to demonstrate that NCM523's original layered crystal structure is recovered. For the first time, it is shown that layer to rock salt phase change on the surfaces and subsurfaces of the cathode materials can be reversed if lithium can be incorporated back to the material. The result suggests the great promise of using eutectic Li+ molten salt solutions for ambient pressure relithiation to recycle and remanufacture degraded LIB cathode materials.
Advanced Energy Materials