Production of high-energy 6-Ah-level Li | |LiNi0.83Co0.11Mn0.06O2 multi-layer pouch cells via negative electrode protective layer coating strategy
Yangyang Feng, Yong Li, Jing Lin, Huyue Wu, Lei Zhu, Xiang Zhang, Linlin Zhang, Chuan‐Fu Sun, Maoxiang Wu, Yaobing Wang
Abstract
Abstract Stable lithium metal negative electrodes are desirable to produce high-energy batteries. However, when practical testing conditions are applied, lithium metal is unstable during battery cycling. Here, we propose poly(2-hydroxyethyl acrylate-co-sodium benzenesulfonate) (PHS) as negative electrode protective layer. The PHS contains soft poly (2-hydroxyethyl acrylate) and poly(sodium p-styrene sulfonate), which improve electrode flexibility, connection with the Cu current collector and transport of Li ions. Transmission electron cryomicroscopy measurements reveal that PHS induces the formation of a solid electrolyte interphase with a fluorinated rigid and crystalline internal structure. Furthermore, theoretical calculations suggest that the -SO 3 - group of poly(sodium p-styrene sulfonate) promotes Li-ion motion towards interchain migration through cation-dipole interaction, thus, enabling uniform Li-ion diffusion. Electrochemical measurements of Li | |PHS-coated-Cu coin cells demonstrate an average Coulombic efficiency of 99.46% at 1 mA/cm 2 , 6 mAh/cm 2 and 25 °C. Moreover, when the PHS-coated Li metal negative electrode is paired with a high-areal-capacity LiNi 0.83 Co 0.11 Mn 0.06 O 2 -based positive electrode in multi-layer pouch cell configuration, the battery delivers an initial capacity of 6.86 Ah (corresponding to a specific energy of 489.7 Wh/kg) and, a 91.1% discharge capacity retention after 150 cycles at 2.5 mA/cm 2 , 25 °C and 172 kPa.