Highly Aligned Ultra-Thick Gel-Based Cathodes Unlocking Ultra-High Energy Density Batteries

Increasing electrode thickness can substantially enhance the specific energy of lithium-ion batteries; however, ionic transport, electronic conductivity, and ink rheology are current barriers to adoption. Here, a novel approach using a mixed xanthan gum and locust bean gum binder to construct ultra-thick electrodes is proposed to address above issues. After combining aqueous binder with single-walled carbon nanotubes (SWCNT), active material (LiNi_0.8Co_0.1Mn_0.1O₂) and subsequent vacuum freeze-drying, highly aligned, and low-tortuosity structures with a porosity of ca. 50% can be achieved with an average pore size of 10 μm, whereby the gum binder-SWCNT-NMC811 forms vertical structures supported by tissue-like binder/SWCNT networks allowing for excellent electronic conducting phase percolation. As a result, ultra-thick electrodes with a mass loading of about 511 mg cm⁻² and 99.5 wt% active materials have been demonstrated with a remarkable areal capacity of 79.3 mAh cm⁻², which is the highest value reported so far. This represents a >25× improvement compared with conventional electrodes with an areal capacity of about 3 mAh cm⁻². This route also can be expanded to other electrode materials, such as LiFePO₄ and Li₄Ti₅O₁₂, and thus opens the possibility for low-cost and sustainable ultra-thick electrodes with increased specific energy for future lithium-ion batteries.