Trifunctional Electrode Additive for High Active Material Content and Volumetric Lithium-Ion Electrode Densities

The use of electrode additives such as binder and conductive additive (CA) in addition to high pore volume for electrolytes, results in reduced volumetric energy densities of all battery electrodes. In this work, it is proposed to use poly(furfuryl alcohol) (PFA) conductive resin as a trifunctional electrode additive to replace polyvinylidene fluoride (PVDF) and CA while simultaneously enabling low porosity electrode function. The resultant PFA binder has a long-range ordered structure of conjugated diene, which allow electronic conductivity that leads to a CA-free electrode fabrication process. The oxygen heteroatoms in the PFA structure reduce the diffusion barriers of lithium ions, lowers the amount of required electrolyte/pore volume and thus, increasing electrode density. Serving as a trifunctional electrode additive, a high electrode density of 2.65 g cm ⁻³ of the LiFePO ₄ (LFP) electrode and therefore the highest volumetric energy density of 1551 Wh L ⁻¹ so far. The LFP electrode using PFA binder can achieve a capacity retention of ≈80% and Coulombic efficiency of over 99.9% after cycling for 500 times. The proposed in situ polymerization strategy could revolutionize the electrode process, with the advantages of being simple, environmentally friendly, and easily scalable to industrial applications.