Ion-Permselective Polyphenylene Sulfide-Based Solid-State Separator for High Voltage LiNi_0.5Mn_1.5O₄ Battery

Abstract

The decomposition of commonly used commercial electrolytes under high voltage and the continuous side reactions at the graphite anode make the rapid capacity decay of LiNi0.5Mn1.5O4(LNMO)/graphite full cell during cycling. In this work, we adopt ion-permselective polyphenylene sulfide-based solid state separator (PPS-SSS) for LNMO batteries, PPS-SSS can effectively prevent the proton diffusion, block the HF generated on the LNMO cathode from attacking the anode SEI layer, and mitigate the Mn2+ transfer. The PPS-SSS with anodic polyethylene (PE) protection (PE-PPS-CSSS) significantly improved the cycling performance of LNMO batteries. In the LNMO/Li half-cell system, 93% capacity retention rate can be achieved after 140 cycles at 0.5 C, and in the LNMO/graphite full-cell system, 85% of the initial capacity can be maintained after 100 cycles. Moreover, flight secondary ion mass spectrometry (TOF-SIMS) and X-ray photoelectron spectroscopy (XPS) are applied to explore the interfacial reactions of LNMO/graphite batteries and reveal the key mechanism for the stable cycling using PPS-SSS.

Acid-scavenging separators promise long-term cycling stability of lithium-ion batteries

“…6d. 92 The PPS-SSS layer with ultralow porosity (<9%) and high Li + transference number ( t Li + > 0.8) is capable of conducting Li + in an all-solid state (∼10 −6 mS cm −1 ). However, to achieve high ionic conductivity (>10 −4 mS cm −1 ) at room temperature, it is necessary to cooperate with the liquid electrolyte for practical applications.…”

“…(d) Cross-sectional SEM images of the PE-PPS-CSSS composite separator. Reproduced with permission 92. Copyright 2022, IOP Publishing.…”

“…(e) Cycling performance of the LNMO8|graphite full cells with the PE-PPS-CSSS and PE separator at 25 1C, and the corresponding (f) FTIR curves of PPS-SSS before and after cycles. Reproduced with permission 92. Copyright 2022, IOP Publishing.…”