Advanced Germanium Nanoparticle Composite Anodes Using Single Wall Carbon Nanotube Conductive Additives

Lithium ion batteries have emerged as a technology that can satisfy the energy storage requirements of a variety of applications, from electric vehicles to cell phones and laptops. However, advances in these technologies have created a need for improvements to both the energy density and the power density of lithium ion batteries. One promising strategy is to use higher capacity electrodes with improved rate capability. Anodes consisting of commercially available germanium nanoparticles (Ge-NP) and in-house produced single wall carbon nanotubes (SWCNT) have recently demonstrated specific capacities exceeding 1,100 mAh/g, whereas traditional meso-carbon microbead (MCMB) anodes provide a specific capacity of 300-330 mAh/g. In the present work, Ge-NP-SWCNT composite anodes were fabricated using conventional slurry preparation and blade coating techniques. The effect on rate capability from varying the percentage of SWCNT conductive additive (1%, 2%, and 3% w/w) was measured at different electrode areal capacities (4, 8, and 12 mAh/cm²). Rate performance is shown to improve at higher weight loadings of SWCNT conductive additive, which is necessary for extraction rates above C/5 at higher areal capacities.  Replacing the traditional MCMB composite anode with a Ge-NP-SWCNT anode is predicted to result in a 20% increase in energy density in an 18650 form-factor battery while also showing good performance at higher rates.