Characterization and performance evaluation of lithium-ion battery separators

A Nacre‐Inspired Separator Coating for Impact‐Tolerant Lithium Batteries

“…Lithium batteries using microporous polyolefin separators to isolate the anodes and the cathodes are presently dominant mobile power sources due to their high energy densities, long life‐span, and low self‐discharging rates . Though not the electrochemically active components, the separators strongly influence the performance and in particular the safety of lithium batteries . Although the microporous structure inside the separator is important for the Li + ion migration, this also makes the separator mechanically weak .…”

“…Though not the electrochemically active components, the separators strongly influence the performance and in particular the safety of lithium batteries . Although the microporous structure inside the separator is important for the Li + ion migration, this also makes the separator mechanically weak . Under the stress of external shock, the microporous polyolefin separator can easily deform, accompanied with the change of inside porous network, including the pore closure, leading to the inhomogeneous Li + ion flux in the battery .…”

“…The inner micropores endow the polyolefin separator with the ability to conduct the Li + ion homogenously . However, the microporous structure in the polyolefin separator is not strong enough to resist the compressive stress, which would lead to the damage of fragile dimensional structure and the shape change of pore network in the separator.…”

“…[4][5][6][7] Although the microporous structure inside the sepa rator is important for the Li + ion migra tion, [4,8] this also makes the separator mechanically weak. [4,9] Under the stress of external shock, the micro porous polyolefin separator can easily deform, accompanied with the change of inside porous network, including the pore closure, [10] leading to the inhomogeneous Li + ion flux in the battery. [11] The nonuniform Li + ion flux can then create high local current density to trigger lithium dendrite growth on the electrode, resulting in short circuit and even explosion of lithium batteries.…”

“…The inner micropores endow the polyolefin separator with the ability to conduct the Li + ion homogenously. [4,6,7] However, the microporous structure in the polyolefin separator is not strong enough to resist the compressive stress, which would lead to the damage of fragile dimensional structure and the shape change of pore network in the separator. Although the commercialized separator is protected by the ceramic nano particle coating, the stress applied on the surface of polyolefin separator still exhibits highly localized distribution character istic because the randomly packed ceramic nanoparticle cannot disperse the stress, implying that the catastrophically perfo rated damage would also occur in the commercialized CNCS (Figure 1a).…”