Reinforcing Li-rich layer cathode via artificial surface reconstruction of spinel shell containing Ni3+

Abstract To achieve cathode materials with satisfactory electrochemical performances, the in-situ artificial reconstruction of spinel shell on Li-rich layer cathode is explored via surface pretreatment strategy. A series of physical characterizations prove that the in-situ evolution of the spinel outer layer containing a certain amount of Ni3+ guarantees the evenly distribution and closely connection with the layered matrix. When the amount of surface pretreatment agent ammonium persulfate reaches 2%, the cathode material exhibits remarkable electrochemical performances with a discharge capacity of 280.2 mAh g−1 at 0.1 C, discharge capacity of 141.9 mAh g−1 at 5 C, and capacity retention of 90.1% after 200 cycles at 1 C. The further exploration reveals that the enhanced electrochemical performance is attributed to the accelerated of Li+ diffusion (DLi+=6.06 × 10−15 cm2 s−1) and reduced the internal impedance of the battery. In addition, the spinel outer layer can prevent the active material from contacting the electrolyte, inhibit the formation of an inert layer, and alleviate the spinel structure penetration into the interior. The robust modification strategy is believed to be an effective approach for promoting the discharge capacity, rate performance, and cycle stability of the cathode material and retarding the voltage decay.