Lithium‐Conductive In Situ Polymeric Additive to Boost Thick Cathodes Via Dry‐Film Technology for High‐Energy‐Density Li‐Ion Batteries

ABSTRACT The dry‐film technology offers significant advantages over conventional wet‐coating methods for high‐loading electrode manufacturing, thereby enhancing the energy density of lithium‐ion batteries (LiBs). However, the insufficient particle adhesion and Li‐ion conductivity of polytetrafluoroethylene (PTFE) binder not only compromises mechanical stability but also accelerates capacity degradation for thick cathodes. The Ni‐rich cathode material, despite its high energy density, also suffers from inherent instability issues. To address the above problems, the lithium‐conductive in‐situ polymer, PL‐Li, is used as a multifunctional additive for thick cathodes, which possesses i) a protective layer bonded to active materials and improves the stability of Ni‐rich cathodes, ii) accelerated ionic/electronic transport efficiency of PTFE and continuous ion transport channels in thick cathodes, and iii) high elasticity to boost the mechanical robustness and benefit for the formation of thick cathodes with high mass loading of 90 mg cm −2 (∼20 mAh cm −2 ). With Ni96 cathodes and Si/C anodes, a 17.9 Ah pouch cell attains an energy density of 397 Wh kg −1 , and maintains 88.1% capacity after 200 cycles at 1C. This strategy not only enables precise tuning of key components in dry‐film technology but also improves the functionality of thick electrodes, making them more suitable for high‐energy‐density LiBs.