High-valence Ni3+ construction and stability by electrochemical de-lithiation boosting oxygen evolution

The development of inexpensive and efficient oxygen evolution reaction (OER) catalysts is crucial for the large-scale application of water splitting to produce green hydrogen. Different from traditional preparation methods, in this study, the electronic structure of ternary NCM (LiNi0.94Co0.05Mn0.01O2) was directly reconstructed from the cathode of spent lithium-ion batteries through electrochemical de-lithiation technology to obtain efficient OER catalysts. The optimized NCM94-1V-90 min exhibits a low overpotential of 270 mV at 10 mA cm(-2 )along with excellent stability for a 300 h durability test. The high OER performance is attributed to the electronic structure reconstruction and microstructure transformation during electrochemical de-lithiation, which generates a large number of high-valence Ni3+ and O vacancies as well as structural fragmentation, respectively, supplying more active sites and enhancing electronic conductivity, also confirmed by the density functional theory (DFT) theoretical calculation. The strategy of electrochemical de-lithiation technology to improve the OER electrocatalytic performance not only can recycle the cathode materials of lithium-ion batteries, but can also be extended to other electrode materials of spent batteries.