Self‐Assembled Mesoporous Nickel Polyphthalocyanine/Graphene Microspheres for Room‐Temperature Sensing of Carbonate Ester Leakage in Batteries

Abstract

ABSTRACT The low viscosity of linear carbonate esters improves electrolyte wetting and ionic conductivity, making them essential for battery operation, but also rendering them prone to rapid evaporation when cells are mechanically damaged or leaking. Given their high flammability, such evaporation poses serious safety hazards. Monitoring such emissions without elevating temperature is critical for providing early hazard warning. Herein, we report a room temperature operable carbonate esters sensor based on self‐assembled mesoporous nickel polyphthalocyanine/graphene microsphere. This spherical structure suppresses π–π stacking of the polyphthalocyanine layers, exposing abundant Ni–N 4 active centers for coordination with carbonate esters. The mesoporous architecture establishes 3D diffusion pathways, facilitating rapid gas transport. The extended π‑conjugation and enriched electron density further enhance the adsorption affinity of Ni–N 4 sites toward carbonate ester groups. The constructed sensor achieves a 90% response to dimethyl carbonate (DMC) vapor at 20°C within 10 s, with high selectivity and stability under bending, humidity variations, and long‐term standby operation. An integrated DMC‐temperature flexible chip identifies overheating and leakage faults of lithium‐ion battery and locates the leakage point within a battery module. This work enables monitoring of battery breakage under practical operating conditions, forming comprehensive risk assessment for battery management systems.