Surface stabilized porous cobalt polyphthalocyanine with enhanced reversibility for durable lithium storage

Abstract

Cobalt polyphthalocyanines (CoPPcs) are a potential organic anode material for lithium-ion batteries (LIBs) for their tunable microstructure and environmental friendliness. However, its naturally highly compact stacking structure hinders the kinetics of lithium-ion diffusion, and its unstable chemical property deteriorates the surface and structural stabilization. A strategy of incorporating the coordination reaction and the exfoliation process is proposed to configure lamellar porous CoPPcs with stabilized surface/structure. An organophosphate compound of trioctylphosphine oxide (TOPO) is strategically introduced in the preparation of CoPPc to achieve the target. The study demonstrates that the optimized porous CoPPc with less stacking structure exhibits enhanced reversible capacity retention of 854.9 mAh g⁻¹ after 500 cycles at 200 mA g⁻¹, showing excellent electrochemical stability prior to the previously reported results. In addition, the designed CoPPc maintains an amazing high capacity of 963.6 mAh g⁻¹ after 1000 cycles even at a relatively high current density of 1 A g⁻¹, presenting a high endurability for rapid charging-discharging process. This work provides a new avenue to rationally modify and stabilize the structure for high-performance organic anodes for LIBs.