Thin Solid Polymer Electrolyte with High-Strength and Thermal-Resistant via Incorporating Nanofibrous Polyimide Framework for Stable Lithium Batteries.

Polyethylene oxide (PEO) based polymer electrolytes show promise in expanding the practical applications of lithium (Li) batteries. However, their applications in Li batteries are usually restricted owing to the lack of mechanical strength, poor oxidative stability, and relatively large thickness. Herein, a nanofibrous polyimide (PI) framework enhanced plasticized-PEO solid electrolyte is prepared to realize good mechanical and electrochemical performances. Following the configuration with the PI matrix, this "polymer in polymer" composite electrolyte with a thickness of 17.5 µm exhibits enhanced mechanical strength (13.9 MPa) and outstanding thermal stability. Additionally, it preserves the high ionic conductivity (2.25 × 10-4  S cm-1 , 25 °C). The Li||Li symmetrical battery with the modified electrolyte could achieve a steady Li plating/stripping of more than 500 h, and the critical current density reaches up to 0.6 mA cm-2 at ambient temperature. The LiFePO4 batteries delivery favorable capacity of 132.2 mAh g-1 with capacity retentions of 96.4% and 85.9% after 500 and 1000 cycles at 1 C, respectively. Acceptable cycling performance also could be achieved in LiNi0.5 Co0. 2 Mn0. 3 O2 solid batteries via an inorganic-rich artificial cathode electrolyte interphase.

Benzoquinone-Based Polyimide Derivatives as High-Capacity and Stable Organic Cathodes for Lithium-Ion Batteries.

Multicarbonyl polyimide derivatives were synthesized by a facial condensation polymerization of dianhydrides with a new diamine monomer containing a benzoquinone unit that was prepared according to the Michael addition reaction. The ingenious combination of dedicated carbonyl groups from the benzoquinone and dianhydride with an aniline structure linkage not only provided stable polymeric chains with a high number of carbonyl groups per unit but also guaranteed their large π-conjugated main chains, which is favorable to their long cycle life and fast kinetics. When explored as cathode materials for lithium-ion batteries, the polyimide derivatives based on naphthalic dianhydride delivered a reversible specific capacity of 145 mAh/g at 0.1 C, a high rate performance with a capacity of 108 mAh/g at 1 C, and an ultralong stable cyclic performance with a capacity retention of 80.3% after 1000 cycles at 0.5 C. Based on the theoretical calculations and the exploration of the electrochemical behaviors, sensible predictions for the reversible ion-insertion reaction of the as-prepared sample were proposed to deeply understand the charge storage mechanisms. Moreover, a stable solid electrolyte interphase film formed in the ether-based electrolyte was confirmed to improve the electrochemical properties.