Dry-processed cathode with Li+-carrier composite binder fiber for high energy density lithium-ion battery

The application of high energy density battery presents challenges for high loading electrode to achieve good performance. Polytetrafluoroethylene fibrillation results in unique advantages including high tap density, non-pollution, and thick electrodes. However, with an increase in electrode thickness, Li + transport within a dry cathode with a low porosity is particularly limited. Additionally, the binder currently used in the dry-film process suffers from poor conductivity and viscosity , resulting in a lithium-ion battery with poor cycling stability and rate performance. In this study, we developed a dry ultra-high-loading cathode using a Li + -carrier composite binder , which facilitated Li + migration and ensured good interfacial contact between the active material particles (LiNi 0.5 Co 0.2 Mn 0.3 O 2 ). This was attributed to the high dispersion performance of polyacrylonitrile and its interactions with Li + . Density functional theory analysis revealed that the composite binder exhibited a homogeneous electrostatic potential profile and narrow lowest unoccupied molecular orbital-highest occupied molecular orbital energy gap, thus enhancing its effectiveness in facilitating electron mobility . Therefore, the thick cathode fabricated with the composite binder displayed a high discharge capacity of 170.4 mAh g −1 (200 μm, 9 mAh cm −2 ) at 0.1C and a stable cycling performance, retaining 80.8 % of its initial capacity after 250 cycles at 0.5C. The single-layer lithium-metal pouch cell exhibited a high energy density of 300 Wh kg −1 , and 85.5 % of the capacity was retained after 150 cycles at 0.1C. The cell coupled with high loading (∼200 μm, 53.8 mg cm −2 ) of dry thick cathode electrodes fabricated with Li + -carrier composite binder is successfully prepared. With only single layer cathodes required, the theoretical energy density of the pouch cell can reach 300 Wh kg −1 . The performance enhancement mechanism should be attribute to the introduced PAN, leading to more Li + movements. • Ultra-high loading cathode (∼200 μm, 53.8 mg cm −2 ) are successfully prepared. • The introduced PAN could remarkably modify the electrochemical performance of dry electrode. • In fibrous structure, the introduced PAN can improve homogeneity and facilitate Li + transport. • The method is easy to prepare on a large scale, single-layer pouch cell can provide a high energy density of 300 Wh kg −1 .