Fast‐Charging of Solid‐State Batteries Enabled by Functional Additives Infused into High‐Mass‐Loading Nickel Manganese Cobalt Cathodes

Additive‐infused processing of lithium nickel manganese cobalt (NMC) cathodes enables high mass loadings (≈6.5 mg cm ⁻² ) and fast charging (1.0C) for completely solid‐state polymer‐based lithium metal batteries. Solid‐state batteries (SSBs) are a promising technology for electric vehicles (EVs) and grid‐scale applications due to enhanced safety and energy density, but practical implementation has been limited since their full theoretical capacities are not readily accessible. This is caused by interfacial contact issues between the cathode and electrolyte and interparticle contacts within the cathode, both critical obstacles when striving for competitive energy densities and faster charging. It is demonstrated here that incorporation of brush polymer additives within the cathode refines the electrode morphology and elevates the electrochemical performance of NMC811|Polymer Electrolyte|Li batteries. This approach enables substantially higher mass loadings than previously reported and simultaneously improves cycle life and C‐rate capabilities. Using galvanostatic intermittent titration technique, electrochemical impedance spectroscopy, and cell cycling experiments, the modified cathodes exhibit reduced interfacial/interphasial resistances, more homogeneous lithium‐ion transport, and superior cycling stability. Incorporation of the additives is an effortlessly implementable strategy for industry to effectively overcome critical interfacial limitations, bringing polymer‐based SSBs closer to practical application in EVs and other emerging applications of electrochemical energy storage systems.