Lithium‐Ion Textile Batteries with Large Areal Mass Loading

Li-ion batteries are widely used in current applications such as in cell phones and laptops, and the industry is undergoing rapid expansion. Li-ion batteries are believed to be a major power source for future electrical vehicle applications. [ 1 , 2 ] In a typical Li-ion battery, the electrode materials are electrically contacting the current collector through percolative pathways from conductive additives such as conductive carbons. To increase the total energy stored in a battery, the cells are packed in rolls and stacks and then into modules before fi nal packing in large quantity. [ 2 ] There are dead cell components such as separators, current collectors and packing in Li-ion batteries, which will increase the cost and decrease the total energy density. The total mass of both positive and negative electrode accounts for less than 50% of the total weight. [ 3 ] Traditionally, electrode materials are loaded on the surface of the metal current collector through roll coating methods. The typical thickness for the battery electrode material is ∼ 50 μ m with a mass of ∼ 20 mg/cm 2 . [ 4 ] A higher areal mass loading of battery electrode materials is preferred which will reduce the number of manufacturing steps for achieving the same total energy and also lower the separator costs. However, the traditional architecture of battery electrode materials on fl at metal current collectors does not allow for higher mass loadings due to the following major diffi culties: (1) Thick electrodes tend to delaminate from the fl at current collectors during the high-speed roll-to-roll coating process. (2) The diffi culty of electrolyte penetration through a thick electrode which dramatically increases the cell impedance, and, as a consequence, a loss of energy effi ciency. The concept of three dimensional (3D) battery electrodes has been used previously to enhance the energy per footprint area. [ 5 ]