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.
The demand for energy increases steadily with time due to population and economic growth and advances in lifestyle. As energy usage increases, concerns about environmental pollution associated with the use of fossil fuel are becoming serious. To mitigate these issues and reduce our dependence on fossil fuel, alternative energy technologies based on renewable sources need to be developed and adopted, e.g., solar and wind energies. However, solar and wind energies are intermittent; therefore, it is critical for efficient and economical storage of electricity produced by renewable sources to be competitive.1 Rechargeable batteries are one of the most viable options for electrical energy storage (EES). Rechargeable battery systems, such as lead−acid, nickel−cadmium, nickel metal hydride, and lithium ion batteries, have serviced humankind for over a century with their use in a variety of applications, e.g., portable electronic devices and automobiles. As the functionalities of the portable electronics become more sophisticated and the demand for electric vehicles and storage of electricity from renewable sources increases, advanced rechargeable batteries need to be developed. Cost, energy, power, cycle life, safety, and environmental compatibility are some of the most important parameters to be considered.
