This proposal seeks to advance the next generation of portable energy storage by exploiting the high specific energy intrinsic to the Li-S system. While sulfurs low electrical conductivity and the inhibiting effects of polysulfide dissolution have historically impeded the commercialization of Li-S batteries, we propose to overcome these limitations via the utilization of graphene as a multifunctional component. Our approach leverages this 2D nanomaterial to act as (i) an electrically conductive agent, (ii) a polysulfide trap to circumvent active material loss, (iii) a robust framework to buffer volume expansion during cycling, and (iv) a wrapping agent to build uniform and spherical particles for better electrode casting. Because polysulfide dissolution is a multifaceted problem affecting the entire cell, we shall also investigate a graphene-protected anode and non-flammable electrolyte to improve cycle life performance and overall battery safety.By completion of Phase I, we intend to demonstrate a low cost (< $10/kg), high areal density (> 10 mg/cm2) cathode exhibiting improved cycle life and capacity retention bolstered by our graphene-protected anode and electrolyte formulation. In consideration of these outcomes, and our intent co-develop this technology with several industrial customers, we truly believe DoDs advanced energy goals can be realized through our approach.
This proposal seeks to develop a high-energy lithium-ion battery with enhanced safety enabled by a cost-effective graphene-protected nano-Si anode and a non-flammable electrolyte. Graphene possesses ultra-high mechanical strength and high electrical conductivity, thereby limiting the anode expansion during charging and also improving the utilization of the semi-conductive silicon material. To address the key issue inhibiting commercialization, the extremely high cost of nano-Si, Nanotek has proceeded to develop a highly scalable process to produce Si nanowires directly from low-cost, micron-scaled Si particles (currently $3-$7/kg). This surprisingly simple and effective technology is expected to enable the availability of Si nanowires at a cost less than $15/kg, which is close to the commercial graphite material ($10-$20/kg) but with much higher specific capacity (over 2,000 mAh/g). Nanoteks non-flammable electrolyte technology including solvent-in-salt design and ionic liquids will be evaluated to guarantee the safety of the batteries equipped on aircrafts or electric vehicles. Several goals are expected by the completion of Phase I: (a) demonstration of a low cost (< $20/kg), high-energy graphene-silicon nanocomposite anode; (b) further verification and validation of the prototype cell performance, delivering specific anode capacity of 600-2,000 mAh/g with a cycle life of > 500 cycles and passing preliminary safety specifications.
