Low cost and environmentally benign crack-blocking structures for long life and high power Si electrodes in lithium ion batteries

Abstract

ARTICLE This journal isThe high capacity Si (4200 mAh/g, Li 4.4 Si) commonly undergoes cracking and delamination due to drastic volume change (~300%) during lithiation/delithiation processes in lithium ion batteries (LIBs). In this work, abundant and sustainable natural polymer gum arabic (GA) and low cost polyacrylic acid (PAA) are used to fabricate Si anode with resilient, crack-blocking property. Esterification reaction between GA and PAA establishes a flexible network resulting in reinforced mechanical strength and enhanced coherent strength. Meanwhile, the water vapour resulted from the esterification reaction generates micron-sized pores which relieves the stress and blocks the formation and propagation of cracks. As a result of the crack-blocking effect, the resultant Si anodes present a superior volumetric capacity of 2890 Ah/L. In addition, charge-discharge cycling for more than 1000 cycles is achieved with Li insertion capacity limited to 1000 mAh/g at 1 C rate.

High Capacity and High Density Functional Conductive Polymer and SiO Anode for High-Energy Lithium-Ion Batteries

“…In terms of electrode thickness, the uncalendered electrode with a loading of ∼3.0 mg SiO/cm 2 typically has a thickness of ∼40 μm, corresponding to a porosity of 63% and an electrode density of 0.83 g/cm 3 . When calendered to 30 μm, the laminate has a porosity of 51% and an electrode density of 1.10 g/cm 3 ; when calendered to 28 μm, the laminate has a porosity of 47% and an electrode density of 1.19 g/cm 3 ; when calendered to 26 μm, the laminate has a porosity of 43% and an electrode density of 1.28 g/cm 3 . Note that the density of our functional conductive polymer/SiO-based electrode is comparable to that of the graphite, while maintaining a high areal capacity of 3.5 mAh/cm 2 .…”

“…In this work, we demonstrate that by calendering the electrode in to an optimized porosity, the areal capacity of a conductive polymer/SiO electrode is improved by ∼1 mAh/cm 2 compared to an uncalendered electrode. A marked areal capacity of ∼3.5 mAh/cm 2 is achieved by this simple and effective calendering process, with a high electrode density of ∼1.2 g/cm 3 .…”

“…2,3 However, almost 300% volume expansion occurs as the material transitions from Si to its fully lithiated phase. 4 Because of this large volume change, the electronic integrity of the composite electrode is disrupted, high and continuous surface side reactions are induced, 5 leading to a drastic capacity decay.…”

“…A welldesigned nanostructure was employed to achieve an areal capacity of ∼3 mAh/cm 2 at a C/20 rate. 9 However, this nanoarchitecture has a high porosity in the electrode and the electrode density is calculated as ∼0.33 g/cm 3 . An optimized binder network was applied to a Si/C material and an areal capacity of ∼4 mAh/cm 2 was achieved at a C/10 rate, with a calculated electrode density of ∼0.62 g/cm 3 .…”

“…9 However, this nanoarchitecture has a high porosity in the electrode and the electrode density is calculated as ∼0.33 g/cm 3 . An optimized binder network was applied to a Si/C material and an areal capacity of ∼4 mAh/cm 2 was achieved at a C/10 rate, with a calculated electrode density of ∼0.62 g/cm 3 . 11 A high-density lithium-ion battery leads to a high volumetric energy density, which is especially important for the application in portable electronic devices.…”