Enhanced electrochemical and thermal performances of Ni-rich NCM811 cathodes via polythiophene and carbon nanotubes co-modification

NCM811 cathode is surface modified by PTh and CNTs. • PTh/CNTs co-modification boosts electrochemistry and thermal stability. • The co-modified sample achieves 86.8% capacity retention after 500 cycles at 1C. • Conjugated electron-rich PTh captures ROS; CNTs build conductive network. The practical use of Ni-rich cathodes is limited by interfacial instability from reactive oxygen species, poor conductivity, and structural degradation. Polythiophene (PTh) is capable of scavenging reactive oxygen species (ROS); however, its electrical conductivity is insufficient to meet the demands of high-rate applications. To enhance the high-rate performance, a hybrid modification layer composed of PTh and carbon nanotubes (CNTs) has been introduced onto LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM811) via a straightforward wet-chemical method. Morphological and surface investigations confirm that PTh uniformly coats the cathode surface, while CNTs are entangled on the surface of the secondary particles to form a robust conductive network. Electrochemical results demonstrate that PTh effectively shields the cathode from electrolyte degradation, suppresses lattice contraction after prolonged cycling, and scavenges ROS, whereas CNTs significantly enhance electrical conductivity. The optimized CP-NCM811 cathode delivers an initial discharge capacity of 184.5 mAh g −1 at 1C and retains 86.8% of its capacity after 500 cycles. Furthermore, it displays an outstanding rate performance of 161.6 mAh g −1 at 10C. The enhanced electrochemical and thermal stability arises from the synergistic effects of ROS scavenging by PTh, suppression of irreversible lattice contraction, and reduction of charge-transfer impedance facilitated by the CNT conductive network. Differential scanning calorimetry further reveals that the modified cathode exhibits a delayed exothermic onset temperature, indicating superior thermal stability. This study offers a novel and efficient strategy for enhancing the electrochemical and thermal performances of high-capacity cathodes through the synergistic co-modification of PTh and CNTs. Download: Download high-res image (186KB) Download: Download full-size image