The Decay Mechanism Related to Structural and Morphological Evolution in Lithium‐Rich Cathode Materials for Lithium‐Ion Batteries

Abstract Li‐rich oxides have garnered intense interest recently for their excellent capacity in rechargeable lithium‐ion batteries (LIBs). However, poor cycling stability and capacity degradation during the cycling process impede their practical application. Herein, two ball‐shaped cobalt‐free oxide materials, Li 1.1 Mg 0.05 Ni 0.3 Mn 0.55 O 2 and Li 1.1 Zn 0.05 Ni 0.3 Mn 0.55 O 2 , which exhibit excellent cycling performance at a high current between 2 V and 4.8 V, are demonstrated. The two Li‐rich materials are prepared from hydrothermally synthesized carbonated precursors. Both oxides exhibit high reversible capacities of 237 and 231 mAh g −1 at 20 mA g −1 , respectively, originating from the redox of Ni 2+ /Ni 4+ and O 2− /(O 2 ) n − . Li 1.1 Mg 0.05 Ni 0.3 Mn 0.55 O 2 presents excellent cycling stability after 200 cycles with 90 % capacity retention. Studies of the structural evolution upon electrochemical cycling implies the cathodes undergo a volume expansion, which results in continuous expanding, cracking, and crushing of the spherical particles, which further induces capacity fading in the cathodes.