Advanced Automotive Battery Conferences

Session 2:
 

Lithium-Ion Cell Engineering

Dr. Spotnitz is a leading developer of mathematical models that simulate battery operation. Dr. Spotnitz, who previously held several senior technical positions in materials and battery development, founded Battery Design in 1999 to provide consulting and develop custom software for battery developers and users. He is a well-known speaker on various aspects of battery engineering.

1. Multilayer Electrode Coatings
   Robert Spotnitz, President, Battery Design LLC
   

   The use of extrusion coating for lithium-ion battery electrodes enables the practical possibility of using multilayer coatings to improve battery performance. The use of multilayer coatings of different materials, for example, a LiFePO⁴ coating next to a LiCoO² coating, or a NMC coating next to a LiMn²O⁴ coating, has been experimentally tested in the literature and modeling approaches to optimize multilayer coatings presented. In this presentation simulation results exploring the effects of particle size and layer thickness are explored in order to minimize the cost of a HEV battery, and some case studies presented for high-energy cells.

   To minimize the cost of a HEV battery, bilayer coatings for both positive (NMC) and negative (graphite) electrodes are considered where layer thickness and particle size are adjusted. For very thin coatings (≤ 40 mm), the simulated performance of bilayer coatings containing different particle sizes is comparable to a single-layer coating containing a mixture of particle sizes. In both cases a substantial benefit comes from using a larger fraction small size particles (~ 1 mm radius), but small particles lead to greater impedance growth and capacity fade over time.

   For the thicker electrodes typically used in energy cells, simulations indicate that the pulse power capability can be increased by using multilayer electrode coatings. However, for battery electric vehicles, the benefit is not clear as the power requirement is not difficult to meet with conventional single layer electrodes.

2. Coated Separator and Li-Ion Cell Safety
   Lie Shi, VP and Chief Technical Officer, Celgard
   

   Separator technology is rapidly advancing, thus enabling battery makers to stay ahead of the increasing challenges of battery performance demands – and ultimately the vehicles they power. The unique combination of advanced ceramic coatings and specifically engineered high-performance base films are the key to this success. Celgard’s expertise in battery materials design, particularly with regards to EDV requirements such as safety, longevity and performance, are critical ingredients that drive focused innovation in our separator technology. This presentation will illustrate how our patented advanced ceramic coating on high-performance base film provides benefits such as enhanced internal short prevention, excellent structural integrity at high temperatures, and improved oxidation resistance as charging voltage increases significantly in xEV battery designs.
3. Recent Advances in Binder Technology
   Ramin Amin-Sanayei, Global Technical Leader of LIB, Fluoropolymer Division, Arkema
   

   There is a strong market demand for a Li Ion Battery that can have higher volumetric storage capability and lower cost, in order to enable wide range of vehicle electrification.

   The key performance requirements for binder is to provide adhesion between electrode and current collector as well as cohesion between electrode particles, while minimizing parasitic reaction. Although, binder is not an active part of the cell, it is enabling component which contributes to weight, volume, and cost of the battery.

   This presentation outlines requirements for high performance binders for next generation LIB and illustrates the recent advances in binder synthesis technology to reduce weight, volume and cost.

   Design and performance of next generation binders:

   • Understanding the effect of polymer characteristics on LIB process
   • Examining effect of Mw on adhesion and developing strategy to maximize adhesion
   • Impact of binder composition on battery performance
   • Reducing binder loading to below 2%
   • Impact of waterborne binders on manufacturing cost 
   • Performance evaluation of next generation binders

   The presentation concludes with a summary and a discussion of future concepts for binders.
4. High-Speed Laser Process for Rapid Electrode Wetting of Battery Materials
   Johannes Proell, Research Scientist - Laser Materials Processing, Institute for Applied Materials (IAM-AWP), Karlsruhe Institute of Technology (KIT)
   

   A critical step in lithium-ion pouch cell manufacturing is to realize homogeneous electrolyte wetting by expensive and time-consuming vacuum and storage processes at elevated temperatures. An advanced laser process has been developed which enables a significant improvement of electrode and separator wetting and battery performance. Investigations for testing the process on pouch cell geometry revealed higher capacities and increased cycle numbers compared to standard cells without storage processes. We present a recently developed high-speed laser structuring technique which can be integrated in existing battery production lines.
5. Scalable, Low-Cost Roll-to-Roll Pre-Lithiation Process
   Ron Wohl, Chief Executive Officer, Nanoscale Components
   

   Nanoscale has developed a scalable, low-cost pre-lithiation method that is a key enabler to commercializing high-energy cells with silicon anodes. The novel pre-lithiation method does not use any metallic lithium, and thereby gains a number of advantages.
   The presentation will cover:

   • The unique pre-lithiation technology
   • Demonstrated benefits of using pre-lithiation with silicon anodes in terms of improved energy, cost and cycle life
   • Scalability and safety of the approach
   • Implications for successful cell assembly
   • Attractive cost structure
   • Other uses of the pre-lithiation technology