Asymmetrically coated LAGP/PP/PVDF–HFP composite separator film and its effect on the improvement of NCM battery performance

Abstract

5 Al 0.5 Ge 1.5 (PO 4 ) 3 (LAGP) is an inorganic solid electrolyte with a Na superionic conductor (NASICON) structure that provides a channel for lithium ion transport. We coated LAGP particles on one side of a polypropylene (PP) separator film to improve the ionic conductivity of the separator, and waterdispersed polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP) on the other side to reduce the interfacial resistance between the separator and the lithium metal anode. The results show that the LAGP/PP/PVDF-HFP separator has a high ionic conductivity (1.06 mS cm À1 ) at room temperature (PP separator: 0.70 mS cm À1 ), and an electrochemical window of 5.2 V (vs. Li + /Li). The capacity retention of a NCM|LAGP/PP/PVDF-HFP|graphite full cell is 81.0% after 300 charge-discharge cycles at 0.2C. When used in a NCM|LAGP/PP/PVDF-HFP|Li half-cell system, the initial discharge capacity is 172.5 mA h g À1 at 0.2C, and the capacity retention is 83.2% after 300 cycles. More significantly, the surface of the Li anode is smooth and flat after 200 cycles. The interface resistance increased from 7 to 109 U after 100 cycles at 0.2C. This indicates that the synergistic effect of the asymmetric coated LAGP and PVDF-HFP is beneficial to inhibiting the growth of lithium dendrites in the battery and reduces the interface resistance.

Sulfide and Oxide Inorganic Solid Electrolytes for All-Solid-State Li Batteries: A Review

“…For example, the use of phosphorous source (H 3 PO 4 ) as precursor provides the best LAGP phase purity and the highest ionic conductivity of ~5 × 10 −4 S cm −1 at 25 °C. In addition, few studies on the synthesis, conductivity (~4 × 10 −4 S cm −1 , see Table 3 [ 365 ]) and interface mechanisms, and physical and electrochemical properties of LAGP have been published since 2019 [ 49 , 342 , 394 , 395 , 396 , 397 , 398 , 399 , 400 , 401 , 402 , 403 , 404 , 405 , 406 , 407 , 408 , 409 , 410 , 411 , 412 , 413 , 414 , 415 , 416 , 417 , 418 , 419 , 420 , 421 , 422 , 423 , 424 , 425 , 426 , 427 , 428 , 429 , 430 , 431 , 432 , 433 , 434 ...…”

Lithium-Ion-Conducting Ceramics-Coated Separator for Stable Operation of Lithium Metal-Based Rechargeable Batteries

“…One promising way to overcome this problem is to replace the insulating ceramic fillers with Li-ion-conducting solid electrolytes [ 35 , 36 , 37 ]. In this study, a facile and scalable blade coating method is used to apply an inorganic/organic composite solid electrolyte layer to the commercial PE membrane separator in order to enhance the stability at the electrolyte–Li metal interface.…”

Ultraviolet-Cured Al2O3-Polyethylene Terephthalate/Polyvinylidene Fluoride Composite Separator with Asymmetric Design and Its Performance in Lithium Batteries

“…Scheme 1 is a schematic of the production process and composite structure of the UV-cured composite film. The weight method was used to calculate the electrolyte uptake rate of the samples, 8 and the porosity was measured by the n-butanol method. 38 A microflow porosimeter (CFP-1500A, PMI, India) was used to measure the pore size.…”

“…The PVDF-HFP, which is stable to lithium, swells and gels after absorbing electrolyte but fits the anode well, even if the volume of the lithium anode changes during cycling, thereby creating a uniform flow of lithium ions on the anode surface and inhibiting the formation and growth of lithium dendrites. 8,47 3.4.5. Effect on the Separator/Electrode Interface.…”