nz9b02739_si_001.pdf (635.08 kB)
Increasing Poly(ethylene oxide) Stability to 4.5 V by Surface Coating of the Cathode
journal contribution
posted on 2020-02-25, 13:05 authored by Kaihui Nie, Xuelong Wang, Jiliang Qiu, Yi Wang, Qi Yang, Jingjing Xu, Xiqian Yu, Hong Li, Xuejie Huang, Liquan ChenSuccessfully
commercialized poly(ethylene oxide) (PEO)-based solid
polymer batteries (SPBs) are expected to continuously play a key role
in the next generation of high-energy density lithium-ion battery
technologies. However, the introduction of high-voltage cathodes,
accompanied by safety concerns such as PEO decomposition and the associated
gas release, is worthy of more attention. This study employs in situ
DEMS to study the gassing behavior of LiCoO2|PEO-LiTFSI|Li
SPBs. The experiments, together with theory calculations, reveal that
a surface catalytic effect of LiCoO2 is the root cause
of the unexpected H2 gas release of PEO-based SPBs at 4.2
V. The surface coating of LiCoO2 with a stable solid electrolyte
Li1.4Al0.4Ti1.6(PO4)3 (LATP) can mitigate such a surface catalytic effect and therefore
extend the stable working voltage to >4.5 V. The crossover effect
of HTFSI, which is generated at the cathode side due to oxidation/dehydration
of PEO and reacts with lithium at the anode side, is proposed to explain
the H2 generation behavior.