From spent lithium-ion batteries to high performance sodium-ion batteries: a case study

Owing to the increasing demand on the valuable metals and growing awareness on the environmental protection, efficient recycling of spent lithium-ion batteries (LIBs) has attracted great concerns recently. Apart from their reuse for LIBs, the recycled electrode materials from spent LIBs for other applications is also an important research direction. Sodium ion batteries (SIBs) are ideal alternatives to LIBs due to the more abundant natural sources of Na than Li and their similar electrochemical mechanism. Herein, we develop a simple and efficient approach for the synthesis of expanded reduced holey spent graphene oxide (c-rhSG) and carbon-coated Na2FePO4F (NFPF) based on the lithiated graphite (LixC6) anode and delithiated Li1-xFePO4 cathode from spent LIBs as starting materials, respectively. For half-cell applications, both c-rhSG and carbon-coated NFPF electrodes display outstanding sodium storage properties. With the use of c-rhSG as anode and carbon coated NFPF as cathode, the full-cell SIB demonstrates a high reversible capacity of 116.3 mAh/g at 0.1 C, excellent rate capability (e.g., 57.7 mAh/g at 5 C) and long cycling stability over 500 cycles.