A unique redox active ion-electron conductor enabled 5C fast-charging graphite anode for lithium-ion batteries

Abstract

Enhancing the charging rate of lithium-ion batteries is poised to accelerate the rapid promotion of electric vehicles, decrease greenhouse gas emissions, and reduce the energy crisis worldwide. However, during the fast-charging process, the slow transport of ions and electrons in the graphite anode makes it challenging to achieve a high capacity and good reversible capability. A multifunctional binder that can realize redox reactions with excellent ionic/electronic conduction is reported herein. The electronic/ionic conductance composition is analyzed for the Li-SPODs binder. Thereinto, the total conductivity of Li-SPODs (0.82 mS cm−1) is divided into three parts: lithium sulfonate ionic conductivity (0.54 mS cm−1) in the eigenstate state, electronic conductivity (1.7 × 10−4 mS cm−1) in the doped state, and doping lithium ionic conductivity(0.27 mS cm−1) in the doped state. The conductivity splitting of Li-SPODs binder can reveal the distinct effect of both conductances on graphite electrodes. Benefiting from the high conductive Li-SPODs binder, the contact resistance of the graphite electrode decreased by 54.4 % compared to the carboxymethyl cellulose/butadiene styrene rubber (CMC/SBR) binder. Meanwhile, the full cell based on the lithium iron phosphate cathode and graphite anode (the areal capacity of 2 mAh cm−2) exhibits an extraordinary capacity and outstanding cycling stability (0.04 % capacity decay per cycle during 500 cycles) even at 5C. More importantly, this novel design strategy provides new insight into preparing a multifunctional binder for fast-charging electrodes with high power and energy.