A highly conductive and stable hybrid solid electrolyte for high voltage lithium metal batteries

Understanding Li+ migration behavior in hybrid solid-state electrolytes (HSEs) is essential for realizing the conductivity of HSE and high energy density Li metal batteries. Here, a highly conductive HSE with a continuous lithium-ion (Li+) transport pathway consisting of an anionic-type single Li+ conductor polymer (lithium taurine-grafted poly(vinylidene fluoride-co-hexafluoropropylene) (P(VDF-HFP)-Li-x, x represents the amount of lithium taurine)) and Li1.4Al0.4Ti1.6(PO4)(3) (LATP) particles are prepared for solid-state lithium metal batteries. The prepared ionomer P(VDF-HFP)-Li-x can enhance the transmission efficiency of Li+ in the polymer substrate, forming a Li+ transport bridge between inorganic particles to provide rapid and continuous Li+ transmission channels in HSE, and eliminating interface charge accumulation caused by an excessive impedance difference of the polymer/ceramic. The P(VDF-HFP)-Li-10-50LATP HSE possesses high ionic conductivity (7.88 x 10(-4) S cm(-1) at 25 degrees C), Li+ transference number (t(Li)(+) = 0.61) and electrochemical stability (>5.16 V vs. Li+/Li). Furthermore, the Li||HSE||Li symmetrical battery achieves a stability over more than 1000 h at 0.1 mA cm(-2), while the HSE-based LiNi0.6Mn0.2Co0.2O2 (NCM622)||Li and LiNi0.5Mn1.5O4 (LNMO)||Li batteries show high specific capacity (160 mA h g(-1) and 126.8 mA h g(-1) at 0.5C) and good cycling stability (capacity retention of 93% and 80% after 200 cycles, respectively). This work provides a an effective to achieve high ionic conductivity and stability for HSEs, simultaneously.

Automated summary

Understanding the Li+ migration behavior in hybrid solid-state electrolytes (HSEs) is crucial for achieving conductivity and stability in HSEs. In this study, a highly conductive HSE with a continuous Li+ transport pathway was prepared, resulting in high ionic conductivity and electrochemical stability. Symmetrical battery and HSE-based Li-ion batteries showed good cycling stability and high specific capacity.