11. Li-ion battery separators – today’s solid electrolytes

Battery 1 Minute
Why “liquid” Li-ion cells are actually “semi-solid” hybrids.

Paper link

Corresponding author link

Paper discussing separator tortuosity by Gasteiger group

Voltage drop can be as high as 0.18V (losses: >15% of total energy) across a 16 micron separator if battery is operated at 5C.

Today’s “liquid cells” are in fact solid/liquid hybrids where liquid electrolytes make up only 30% to 40% of the volume between anode and cathode. Separators are the porous polymeric membranes which (electrically) insulate the anode from the cathode. They house the ionically conductive liquid electrolyte in their empty pores and govern the energy density, cycle life and safety of lithium ion cells even though they are inert components. This 2018 Nature paper discusses the role of separators as well as several critical parameters used to characterize them, such as effective conductivity, transfer coefficients, diffusion constants, porosity, tortuosity, Gurley values, permeability and others.

Published by Claudiu “Bobby” Bucur

Claudiu B. Bucur obtained his Ph.D. in 2008 from Florida State University under the mentorship of distinguished Leo Mandelkern Professor of Polymer Science, Joseph B. Schlenoff. He studied the manner in which polyelectrolyte multilayers assemble, and how doping them with ions changes their mechanical and thermodynamic properties. In 2010 he completed his postdoctoral studies at the USDA Agricultural Research Service Labs, where he investigated corrosion inhibition via biomembranes. Dr. Bucur then joined the Post Lithium Ion Research Group at the Toyota Research Institute of North America, where he focused on metallic anodes such as magnesium, lithium, sodium, and their electrolytes as well as high capacity conversion cathodes such as the sulfur cathode. He expanded upon his experience with polymers, corrosion, and interfaces and was able to advance many areas in the battery field. Currently, Dr. Bucur is Chief Engineer for new battery and solid electrolyte projects at Great Wall Motor, the largest SUV manufacturer in China. He is fascinated by energy storage and dreams of creating the ultimate battery.

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2 thoughts on “11. Li-ion battery separators – today’s solid electrolytes”

  1. inorganic materials based separator films could be the best candidates for thermal stability avoiding any short circuits between anode and cathode, I am related with separator films for lithium ion battery
    we believe, the electrospun technology could be beneficial in this regard

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  2. Pingback: 20. Stable lithium plating with 3x capacity of commercial Li-ion cells… apparently possible @Stanford – Claudiu's Lithium Ion Battery Reviews

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