Structural engineering for double-layer high-load LiFePO4 electrode with vertical imparity distribution of conductive additives

Abstract

To improve the energy density of the batteries, constructing electrode structure should also be considered besides developing high specific capacity electrode materials. As the active material loading increases, the electrode rate performance worsens due to the long distance of electron transport and ion diffusion. This study proposes a simple and effective strategy to construct a high-load LiFePO4 electrode with excellent rate performance by using a double-layer structure. The bottom layer with more conductive additives forms a rich conductive network to improve the ability of electronic collection, the top layer with fewer conductive additives increases the porosity to facilitate ion diffusion. The capacity of the double-layer electrode (active material loading 11.4 mg cm−2) with imparity distribution of conductive additives achieves 98 mAh g−1 at 425 mA g−1 (2.5C). However, the capacity of the single-layer electrode is zero even at a lower loading (7.1 mg cm−2). The vertical imparity distribution of conductive additives in the double-layer structure can reduce the polarization and maintain the excellent rate performance of the high-load electrode. This strategy can be used not only in lithium-ion batteries but also for other energy storage systems possibly.