Integrated Ni and Li‐Rich Layered Oxide Cathode Materials for High Voltage Cycling in Rechargeable Li‐Ion Batteries

Abstract Although the Ni‐rich oxide cathodes possess a high specific capacity above 180 mAh g −1 , they suffer from capacity fading upon cycling to above 4.3 V due to their high surface reactivity with the electrolyte, structural layered to rock‐salt phase transformation and development of micro‐cracks. Herewith, the Ni‐rich oxide is integrated with those of Li and Mn‐rich oxides and their electrochemical performance is evaluated in Li half‐cells: LiNi 0.6 Mn 0.2 Co 0.2 O 2 (NMC622), 0.5LiNi 0.6 Mn 0.2 Co 0.2 O 2 ⋅ 0.5Li 1.2 Ni 0.16 Mn 0.56 Co 0.08 O 2 (NL5050), and 0.25 LiNi 0.6 Mn 0.2 Co 0.2 O 2 ⋅ 0.75 Li 1.2 Ni 0.16 Mn 0.56 Co 0.08 O 2 (NL2575). Interestingly, the resultant integrated 0.5LiNi 0.6 Mn 0.2 Co 0.2 O 2 ⋅ 0.5Li 1.2 Ni 0.16 Mn 0.56 Co 0.08 O 2 (NL5050) cathode with an equal molar concentration of Ni and Li‐rich oxides exhibits a specific capacity of about 190 mAh g −1 with a capacity retention of 83 % after 100 cycles at 0.1 C rate. On the other hand, the Ni‐rich oxide alone although exhibits an initial high specific capacity of 200 mAh g −1 , it suffers from a low capacity retention of only 35 % after 100 cycles. Thus, this study clearly indicates the benefits of higher cycling stability that results from the integration of Ni‐rich and Li‐rich oxide cathodes. Hence, the current work promotes the high voltage cycling of oxides through the optimization of integrated oxide cathodes, which can provide high capacity and long cycle‐life for Li‐ion batteries.