Integral bi-layer separator-electrode construction for lithium-ion batteries

Abstract

A porous bi-layer separator composed of a first layer with a contacting array of non-conducting particles overlaid with a second layer of a microporous polymer layer, may be fabricated on the electrode surface of the anode of a lithium-ion battery to form an integral electrode-separator construction. The bi-layer separator may prevent development of a direct electronic path between the anode and cathode of the battery while accommodating electrolyte solution and enabling passage of lithium ions. Such an integral separator should be mechanically robust and tolerant of elevated temperatures. Exemplary bi-layer separators may be fabricated by sequential deposition of solvent-containing slurries and polymer solutions with subsequent controlled evaporation of solvent. The elevated temperature performance of lithium-ion battery cells incorporating such integral electrode-bi-layer separators was demonstrated to exceed the performance of similar cells using commercial and experimental single layer polymer separators.

Description

TECHNICAL FIELD[0001]This invention pertains to bi-layer porous separators integral with an electrode of a lithium-ion cell to assure electrical separation between the anode and cathode of the cell. More specifically, this invention pertains to the sequenced deposition of conformal, electronically non-conductive, porous ceramic and polymer coatings on one of the cell electrodes to form a cooperating electrode-separator construction.BACKGROUND OF THE INVENTION[0002]Lithium-ion secondary batteries are common in portable consumer electronics because of their high energy-to-weight ratios, lack of memory effect, and slow self-discharge when not in use. Rechargeable lithium-ion batteries are also being designed and manufactured for use in automotive applications to provide energy for electric motors to drive vehicle wheels.[0003]The basic unit of a lithium-ion battery is an individual cell which includes an anode, a cathode and a liquid, non-aqueous electrolyte suitable for carrying and c...

AI Technical Summary

Benefits of technology

[0027]Thus, this invention provides a porous bi-layer separator membrane with an inner ceramic layer which offers increased temperature resistance and increased resistance to penetration, whether by dendrites, metal fines or electrode particles. The ceramic layer, which may be somewhat brittle and prone to spall under vibratory loads, is supported by the more compliant, adherent microporous polymer layer. In turn, the ceramic layer restrains

Problems solved by technology

Lithium-ion secondary batteries are common in portable consumer electronics because of their high energy-to-weight ratios, lack of memory effect, and slow self-discharge when not in use.

But, under normal operating conditions, battery life is affected by the degradation of the active materials (e.g. anode, cathode and electrolyte) and abnormal operation can induce the formation of lithium dendrites, surface d

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