Density, Low-Cost Lithium-Sulfur Batteries Presenter: Dr. Hannah L. - - PowerPoint PPT Presentation

Technology Overview Current Status

To achieve step-change performance with Li-S chemistry, it is imperative to operate at very high sulfur concentrations. Accordingly, we have accomplished the following: 1. Polysulfide electrodes can be reversibly cycled at extremely high sulfur concentrations ( up to 16 MS) in water-based electrolyte. Reversible capacity ranges from 10 to 20 mAh/cm2. 2. PolyPlus has worked with several suppliers to successfully develop a hydrophilic carbon matrix for aqueous sulfur electrodes. 3. Projected performance based on laboratory lithium-sulfur cell testing is ~ 400 Wh/kg and 650 Wh/l

A Revolutionary Approach to High-Energy Density, Low-Cost Lithium-Sulfur Batteries

PolyPlus Battery Company, Berkeley, CA OPEN 2012

• Dr. Steven J. Visco, CEO and CTO

510-841-7242 svisco@polyplus.com Presenter: Dr. Hannah L. Ray

Project Statistics

Award Amount $4.5M Award Timeline February 2013 - February 2016 Next Stage Target 400 mAh Li-S prototype cell at 400Wh/kg, 650 Wh/L Collaborations Sought Strategic Partners, Manufacturing expertise, System Integration.

PolyPlus Battery Company is advancing a novel approach to lightweight, low-cost Li-sulfur batteries based on two technical breakthroughs: 1) The use of a patented, water-stable protected lithium electrode (PLE) to completely eliminate the polysulfide shuttle (self-discharge rate is effectively zero) and permit the use of aggressive solvents in the positive electrode. 2) Replacement of conventional non-aqueous electrolyte with a non-flammable, inexpensive water- based electrolyte that dramatically increases the solubility of Li2S (3000x), eliminating the need for a supporting salt, and increasing the ionic conductivity by more than an order of magnitude.

(Left) Li2S in common non- aqueous solvent (glyme) Extremely low solubility (<1x10-3 mol/L) (Right) Same mass of Li2S in aqueous solvent Completely dissolved

Major Accomplishments

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• PolyPlus has developed aqueous polysulfide electrodes that demonstrate reversible

cycling at exceptionally high sulfur concentration (up to 16 MS).

• PolyPlus has demonstrated long-term stability of the protected electrode (solid

electrolyte) against aqueous polysulfides at high pH, and excellent chemical stability of highly concentrated aqueous polysulfides (no evidence of precipitation for several months).

• We have successfully identified a number of suppliers for high porosity/high surface

area carbon supports that are sufficiently hydrophilic to be used with aqueous polysulfides.

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• It’s important to have a well integrated team that communicates often and well (electrochemistry,

chemistry, materials, mechanical engineering, etc.)

• Prototype engineering for new chemistries in non-trivial (start early)
• Pushing the envelope on performance goals helps identify key fundamental and scientific issues

limiting performance.

• The literature is often wrong.
• Having the ability to write patents internally allows you to move quickly towards protecting

intellectual property, and should lead to stronger IP.

• Build many, many, cells. Reproducibility is critical to moving the needle.
• It helps to have big friends:

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When trying to convince large companies to modify existing products for new applications (like Li-S batteries), the ability to call in the big guns to make a phone call helps.

Lessons Learned

Collaborations specifically looking for – technical & T2M

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• PolyPlus is always interested in strategic partners that can either accelerate the

manufacture and scaling of our step-change battery technology, or have an internal strategic need for this advance.

• A key component in aqueous Li-S technology is the high porosity carbon support.

Although we have identified several companies that make such materials, we are particularly interested in alternative high porosity and high surface area hydrophilic carbons that can be scaled at low cost.

• We are still pre-revenue and therefore have an enduring need for funding and/or

strategic investment.

Value Proposition

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