P-Doped Ni/NiO Heterostructured Yolk-Shell Nanospheres Encapsulated in Graphite for Enhanced Lithium Storage.

The development of high-efficiency lithium-ion battery electrodes composed of recycled materials is crucial for the commercialization of retired batteries, but it remains a significant barrier. The usage and recycling of spent graphite are encouraged by the huge number of batteries that are going to be dismantled. Here, an anode made of phosphorus-doped Ni/NiO yolk-shell nanospheres embedded on wasted graphite is developed. Electroless deposition and a subsequent heat-treatment procedure are used to make it in a methodical manner. The internal vacuum space of the nanospheres mitigates volume expansion and facilitates Li+ diffusion, whereas the embedded metallic Ni and conductive graphite layer expedite charge transfer. The optimal reusable composite electrode is ecologically benign and has high specific capacities (724 mAh g-1 at 0.1 A g-1 ) as well as outstanding cycle stability (500 cycles). The unusual 3D sandwich-like arrangement with strong spent graphite, the yolk-shell hetero-structure, continuous electron/ion transport routes, and attractive structure stability all contribute to this degree of performance. Such a nanoscale design and engineering strategy not only provides a green recovery method for anode graphite, but also enlightens other nanocomposites to boost their lithium storage performance.