Battery Separator for Completely Stopping Dendrite

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OPEN 2021
Ann Arbor, Michigan
Project Term:
03/04/2022 - 03/03/2025

Critical Need:

Dendrite, which causes battery failure and safety hazards due to inner short-circuit, is a key barrier for lithium ion and lithium metal battery use in a wide range of vehicle applications .During charging of lithium ion and metallic lithium cells, lithium ions move toward the anode to store energy. Lithium deposition is inherently unstable. Unavoidable defects such as surface imperfections or random motion of atoms can cause a small protrusion to form on the anode surface. The lithium flux forms a spherical diffusion concentrated toward the tip. The tip grows faster, leading to tiny, rigid tree-like structures called dendrites. Their needle-like projections can pierce a structure known as the separator inside a battery, causing short circuits, which may cause fires. The capability of current mechanical blocking technologies, including a solid-state electrolyte, ceramic-coated separator, reinforced separator, and stiff artificial interface are fundamentally limited by the material strength or availability of alternative pathways in the separator.

Project Innovation + Advantages:

The University of Michigan aims to develop a new type of battery separator that can completely stop dendrite formation. The key innovation is a special mechanism that suppresses dendrite growth with the University of Michigan’s wet-process-synthesized film as a separator or coating. When an electrode surface starts to lose stability upon lithium deposition, any protrusion will cause deformation of the film, generating a local shielding effect that deflects lithium ions away from the tip of the protrusion. This slows down the tip growth and makes the lithium metal surface flat. Lithium ions thus spontaneously deposit to a flat surface without dendrite formation. The dendrite-suppression capability could be several orders of magnitude stronger than the limit of mechanical blocking by current separators or solid-state electrolytes.

Potential Impact:

The new technology’s mechanism ensures lithium deposition to form a flat surface even if the initial substrate surface has significant protrusions, ensuring the safety and viability of lithium ion and lithium metal batteries.


This mechanism could significantly increase the reliable operational window of current Li-ion batteries and ensure their safe operation even when manufacturing defects are present.


By making high-capacity Li batteries viable, this technology could hasten and broaden EV adoption, reducing U.S. reliance on fossil fuels that create harmful greenhouse gas emissions.


This technology would help to maintain U.S. leadership in the $8B separator and $3T EV markets.


ARPA-E Program Director:
Dr. Halle Cheeseman
Project Contact:
Prof. Wei Lu
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Project Contact Email:

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