A silicon (Si) anode is a promising material for next-generation lithium-ion batteries (LIBs). It has high theoretical specific capacity of 3579 mAh/g, nearly ten times larger than that of the graphite anode. This high capacity can significantly enhance the energy density of LIBs, a critical requirement for applications such as electric vehicles and portable electronics. However, the Si anode faces fundamental challenges due to their substantial volume change, up to 400%, upon lithiation and delithiation. This volume change, if repeated, can pulverize active particles, leading to mechanical degradation and loss of electrical wiring, and thereby rapid capacity fading. In this study, we combine two different manufacturing techniques to achieve large capacity and long cycle life for the Si anode. We employ electrowriting that is our unique capability to produce three-dimensional (3D), flexible fiber structures. This pushes the manufacturing limit of electrospinning to produce orientation-controlled fibers with micron precision. We will electrowrite 3D scaffolds that can contain Si-C composite particles produced by electrospraying. These particles are secondary particles that are uniform in size (average diameter ~800 nm) and porosity. Their primary particle size is 40 nm (Si). This controlled porosity can facilitate efficient electrolyte penetration, contributing to improved electrochemical performance. Electrowriting can build 20 x 20 μm grid structures made of 2 µm-diameter polyacrylic acid (PAA) fibers. We found that the electrosprayed Si/C anode delivers 2000 mAh/g at the 20th discharge at C/10 with a capacity retention rate 88.6%. Capacity fading may originate from the weak adhesion force of the sprayed particles, rather than pulverization. Electrowriting can improve the adhesion of electrosprayed Si-C particles, leading to higher capacity retention. Compared with a conventionally prepared Si anode, this construction can accommodate volume change of the Si-C anode upon Li cycling. The polymer-based 3D scaffold can help the anode maintain integrity by effectively dissipating strain energy. We consider that our approach provides a new insight to battery manufacturing that can address challenges in the Si anode.
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