The energy storage performance of lithium-ion batteries (LIBs) depends on the electrode capacity and electrode/cell design parameters, which have previously been addressed separately, leading to a failure in practical implementation. Here, we show how conformal graphene (Gr) coating on Ni-rich oxides enables the fabrication of highly packed cathodes containing a high content of active material (~99 wt%) without conventional conducting agents. With 99 wt% LiNi0.8Co0.15Al0.05O2 (NCA) and electrode density of ~4.3 g cm-3, the Gr-coated NCA cathode delivers a high areal capacity, ~5.4 mAh cm−2 (~38% increase) and high volumetric capacity, ~863 mAh cm-3 (~34% increase) at a current rate of 0.2 C (~1.1 mA cm-2); this surpasses the bare electrode approaching a commercial level of electrode setting (96 wt% NCA; ~3.3 g cm-3). Our findings offer a combinatorial avenue for materials engineering and electrode design toward advanced LIB cathodes.

Li-ion batteries (LIBs) employ porous, composite-type electrodes, where few weight percentages of carbonaceous conducting agents and polymeric binders are required to bestow electrodes with electrical conductivity and mechanical robustness. However, the use of such inactive materials has limited enhancements of battery performance in terms of energy density and safety. In this study, we introduced graphene/polyvinylidene fluoride (Gr/PVdF) composites in Ni-rich oxide cathodes for LIBs, replacing conventional conducting agents, carbon black (CB) nanoparticles. By using Gr/PVdF suspensions, we fabricated highly dense LiNi0.85Co0.15Al0.05O2 (NCA) cathodes having a uniform distribution of conductive Gr sheets without CB nanoparticles, which was confirmed by scanning spreading resistance microscopy mode using atomic force microscopy. At a high content of 99 wt.% NCA, good cycling stability was shown with significantly improved areal capacity (Qareal) and volumetric capacity (Qvol), relative to the CB/PVdF-containing NCA electrode with a commercial-level of electrode parameters. The NCA electrodes using 1 wt.% Gr/PVdF (0.9:0.1) delivered a high Qareal of ~3.7 mAh cm−2 (~19% increment) and a high Qvol of ~774 mAh cm−3 (~18% increment) at a current rate of 0.2 C, as compared to the conventional NCA electrode. Our results suggest a viable strategy for superseding conventional conducting agents (CB) and improving the electrochemical performance of Ni-rich cathodes for advanced LIBs.

Summary Lithium‐ion batteries (LIBs) are the main driving force behind the proliferation of mobile devices and electric vehicles. The production technologies of LIBs have been developed with the aim of lowering the energy cost (US$ kWh−1) and environmental impact while increasing the production efficiency. Here, we report dry‐processed Ni‐rich oxide cathodes coated with carbon nanotubes (CNTs) for LIBs. Specifically, LiNi0.8Co0.15Al0.05O2 (NCA) particles coated with multi‐walled CNTs (MWCNTs) were used to fabricate the cathodes by employing dry‐type electrode processing. In addition, the amount of polytetrafluoroethylene binder in the electrode was minimized and the inclusion of conventional carbon black (CB) conductive additives was eliminated. This approach enabled the fabrication of CB‐free, dense cathodes with an extremely high NCA content (99.6 wt%) and high electrode density of ~4.0 g cm−3. The NCA cathode had a high volumetric capacity of ~821 mAh cm−3 at a current rate of 0.5 C (~4.6 mA cm−2) and delivered good full‐cell cycling performance over 300 cycles (~60% capacity retention). Our results offer a viable way to lower the energy cost and the environmental damage toward next‐generation LIBs. Highlights Ni‐rich particles with a CNT‐coating were used for dry‐processed cathode preparation. The CNTs replace conventional carbon black conductive additives. The CNT‐coated Ni cathodes were fabricated with minimal binder content (0.4 wt%). The cathode has good rate and cycling performance with high volumetric capacities.

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