Constructing Electron/Ion Conductive-Enhanced Ultrahigh Loading LiFePO4 Electrodes Using Polytetrafluoroethylene and Carbon Nanotubes for High-Performance Batteries

Abstract

Thick electrodes represent an effective approach for augmenting energy density of batteries. However, their increased thickness invariably leads to longer electron and ion transport distance, limiting the utilization of active material and hindering practical application. Herein, an electron-conducting-enhanced and ion-conducting-enhanced strategy is presented for fabricating ultrahigh loading electrodes via constructing an interlaced 3D network. Carbon nanotubes (CNTs) serve as extended electron pathways. Different from the polyvinylidene fluoride binder which needs to be dissolved into molecules for preparing electrode, polytetrafluoroethylene (PTFE), however, exists as a separate phase inside the electrode, thus can become the extended pathways for electrolyte elongating due to its strong affinity to organic electrolyte. Note that based on the synergistic effect between CNT and PTFE, the latter can exhibit a form of long-distance extension fibers rather than agglomeration. Finally, a LiFePO₄ electrode with a record-high loading of 141 mg cm⁻² is successfully prepared. This electrode exhibits outstanding area capacity (20.7 mAh cm⁻² at 0.2 C) and cycling stability with impressive energy density of 224 Wh kg⁻¹ and 517 Wh L⁻¹ in a full cell (graphite anode). The findings present a novel strategy for achieving high energy density in lithium-ion batteries using existing material systems.