High-Energy-Density LiNi_0.9Co_0.05Mn_0.05O₂//SiO_x-Graphite Soft-Pack Semi-Solid-State Batteries Using In Situ Solidified Polymer-Based Electrolytes for Practical Applications

The short cycle life and serious safety concerns of high-energy-density Li-ion batteries composed of Ni-rich layered cathodes and Si-based anodes hinder their practical applications, while semi-solid-state battery technology is one of the effective ways to solve these problems. Here, we report a one-pot polymerization self-assembly for in situ constructing pentaerythritol tetraacrylate-azoisobutyronitrile (PETEA-AIBN)-based solid-state electrolytes and study their electrochemical and safety properties in a semi-solid-state LiNi_0.9Co_0.05Mn_0.05O₂//SiO_x-graphite soft-pack battery. The obtained electrolytes feature highly electronegative AIBN grafted onto PETEA to form cross-linked frameworks in which the carbonate electrolyte molecules are in situ immobilized. By tuning chemical interactions among three nanocomponents to optimize the electrolyte’s distribution and Li-ion transport, such a solid-state gel design enables excellent electrochemical properties, showing rapid Li⁺ ionic conductivity (3.2 × 10^–4 S cm^–1) and a high oxidation potential (4.5 V vs Li/Li⁺). Notably, LiNi_0.9Co_0.05Mn_0.05O₂//SiO_x-graphite soft-pack batteries using solid-state electrolytes exhibit an outstanding electrochemical performance. A 1.2 Ah soft-pack battery achieves a high energy density of 323 Wh kg^–1 and a long cycle life of over 400 cycles with a 94.8% capacity retention. More importantly, it exhibits a much improved safety performance under puncture experiments and 150 °C conditions compared with the same type of liquid soft-pack battery.