MXene-reinforced polyimide composites enabling robust organic Li-ion batteries with ultrafast kinetics and cycle durability
摘要
Traditional lithium-ion batteries suffer from poor cycle and rate performance due to low structural stability and the sluggish charge transfer kinetics of cathode during the lithiation and delithiation processes. Polyimide (PI) electrode, known for high theoretical capacity, structural tunability, inherent safety feature and sustainability, have garnered significant attention, offering a promising solution in addressing these issues. Nevertheless, the intrinsic insulation characteristic restricts the capacity of PI material. The emergence of two-dimensional layered Ti3C2Tx MXene with low charge transfer resistance and high electrocatalytic activity is highly suitable for enhancing the electrochemical performance of PI. Therefore, integrating PI with few-layered MXene would combine PI’s abundant redox-active sites with MXene’s excellent conductivity, creating a robust electrode with high capacity, ultrafast kinetics, and cycle durability. Based on this strategy, the hybrid material composed of naphthalene-based PI (NPI) with stable molecular structure and few-layered MXene, denoted as NPI@MXene, has been successfully designed and fabricated through the eco-friendly solid-state polycondensation approach. By adjusting the feed ratio of reactants, the hybrid electrode with 10 wt% MXene (NPI@10%MXene) demonstrates the layer-plus-island-like stable structure and good interaction between NPI and MXene, which delivers the highest rate capacity. Even subjected to a high-current density of 8 A g−1, the NPI@10%MXene composite maintains 74% (~ 84 mAh g−1) of its initial capacity. It also exhibits long-life cycling stability with ~ 77% retention after 5000 cycles (1 A g−1). Moreover, the NPI@10%MXene composite reveals enhanced capacitive effect and fast Li+ diffusion coefficient during the discharge/charge process (1.43 × 10–9/1.43 × 10–9 cm2 s−1, respectively), outperforming those of pristine NPI. The above experimental results highlight remarkable potential of NPI@10%MXene for application in ultrafast Li+ storage. Thus, NPI@10%MXene cathode offers a viable strategy to reconcile rapid electrochemical reaction with long-term stability in sustainable rechargeable batteries.