An unprecedentedly high electronic conductivity of 0.27 S cm⁻¹ is achieved by depositing 0.56 wt% crystalline RuO₂ on LNMO via a wet-chemical route. Systematic assessment of the electrochemical performance of bare and RuO₂-coated LNMO electrodes unambiguously demonstrates that the high electronic conductivity of RuO₂ enables significant enhancement in rate capability. These improvements are dramatic for the electrodes in which extremely low amounts of carbon additives are included and/or the loading amount is high. This finding highlights the importance of electronic conduction in composite electrodes, not only for high power but also for high energy density. The RuO₂-coated LNMO electrode with 1 wt% carbon additives exhibits a high capacity of 100 mA h g⁻¹ at 1C in the range 3.0–5.0 V (vs. Li/Li⁺). This result is in sharp contrast to the negligible capacity exhibited by the bare LNMO electrode. In addition, the chemical/electrochemical stability of the RuO₂ coating under repeated cycling is confirmed, explaining the observed improvement in durability of the RuO₂-coated LNMO over the bare LNMO.