Solvophobic Binder Crystallinity‐Tailored Advances in Solvent‐Free Thick Cathodes for High‐Energy Lithium Metal Batteries

Abstract Developing high‐performance thick cathodes with optimized inactive‐to‐active material ratios is a promising approach to enhance the energy density of conventional lithium‐ion batteries (LIBs). However, increasing electrode thickness introduces challenges, including elevated resistance and mechanical issues such as cracking and flaking, particularly in slurry‐based wet processes. This highlights the necessity for solvent‐free, low‐resistance thick cathode fabrication methods. In this study, the impact of a solvent‐free mechano–thermal fabrication process on the electrochemical performance of high‐nickel ternary metal oxide‐based thick cathodes is explored. A key challenge identified is the formation of solvophobic crystalline structures on the surface of the active cathode materials. To address this, a fast cooling strategy is implemented at the end of the solvent‐free fabrication process, which successfully reduced the solvophobic crystallinity, ultimately surpassing the electrochemical performance of cathodes produced through wet processes. Furthermore, incorporating a PVDF/succinonitrile (SN) mixture binder via liquid‐phase mixing further minimized crystallinity, resulting in significantly improved electrolyte wettability, ionic conductivity, and mechanical adhesion. As a result, the mixture binder system achieved a high areal capacity of ≈11 mA h cm⁻ 2 and demonstrated stable cycling performance over 100 cycles. When paired with a lithium metal anode, the thick cathode attained an energy density of ≈418 W h kg⁻¹, translating to ≈335 W h kg⁻¹ with packaging—representing approximately 35% improvement over current LIB technologies.