Synergistic bulk-surface engineering via cobalt phthalocyanine modulation for high-performance LiNi0.5Mn1.5O4 spinel cathode materials

High-voltage LiNi 0.5 Mn 1.5 O 4 (LNMO) spinel cathodes offer high energy density and cost efficiency for next-generation lithium-ion batteries but suffer from structural degradation and interfacial side reactions. This study addresses these challenges through a cobalt phthalocyanine (CoPc) modification strategy that synergistically integrates bulk doping and surface coating. By neutralizing residual surface alkali and optimizing calcination processes, Co 3+ ions are selectively doped into Mn 4+ sites to expand lattice parameters, while an in-situ-formed Co 3 O 4 nanocoating chemically passivates the surface, suppressing Mn dissolution and promoting stable CEI formation. The optimized LNMO-5 wt% CoPc (using CoPc content is 5 wt%) cathode demonstrates outstanding electrochemical stability, retaining 81.4 % capacity after 700 cycles at 1C and delivering 95.2 mAh g −1 at 20C over 1000 cycles. It also exhibits superior temperature-adaptability with 68.1 mAh g −1 capacity at 5C/-15 °C and 68.3 % capacity retention at 40 °C after 300 cycles at 1C. This work establishes a “bulk-surface” co-optimized framework to resolve the inherent stability-rate trade-off in spinel cathodes, advancing the development of long-term high-power lithium-ion batteries.