Trace Doping of Multiple Elements Enables Stable Cycling of High Areal Capacity LiNi_0.5 Mn_1.5 O₄ Cathode

High-voltage spinel cobalt-free LiNi_0.5 Mn_1.5 O₄ (LNMO) is one of the most promising cathode candidates for next-generation lithium-ion batteries (LIBs) due to its high specific capacity, high operating voltage, and low cost. However, inferior electronic conductivity, transition metal dissolution, and fast capacity degradation of LNMO, especially in high mass loading for high areal capacity, are the critical material challenges for its practical application. Herein, trace multiple Cr-Fe-Cu elements doping of LiNi_0.45 Cr_0.0167 Fe_0.0167 Cu_0.0167 Mn_1.5 O₄ (CFC0.5-LNMO) cathode is achieved by a blow-spinning strategy to exhibit very stable cycling at a practical level of areal capacity up to 3 mAh cm^-2 . It is demonstrated that the Cu, Fe, and Cr doping into the LNMO lattice can suspend the Mn dissolution and improve the Li ion diffusivity and electronic conductivity of the LNMO host. As a result, the obtained CFC0.5-LNMO cathode exhibits an excellent rate performance (1.75 mAh cm^-2 at 1C) and long cycling stability under an areal capacity of 3 mAh cm^-2 (78% capacity retention over 300 cycles at 0.5C).