There is increasing research attention on optimizing the carbon black nanoparticles' structure and loading procedure for improving conductivities and thus, electrochemical performances of cathodes in lithium-ion batteries. Recently, LiNi 0.5 Co 0.2 Mn 0.3 O 2 (NCM523) has been actively investigated due to its larger specific capacity and lower cost compared to conventional cathode materials. Presented here is a high energy density NCM523 cathode obtained by reducing the carbon content using the state-of-the-art carbon nanoparticles developed at Cabot Corporation. It is the first time that the nonlinear conductivity of NCM523 electrodes has been discovered, which is significantly impacted by the dispersion and surface crystalline quality of carbon black nanoparticles, especially when the loading of carbon black is only 1 wt%. The nonlinear conductivity of the cathodes can dramatically affect their electrochemical performances at high rates ( 3C), which is close to the tunneling saturated current. In addition, there is no discernable difference in terms of the rate and cycle performance of the NCM523 electrodes, when reducing the loading of novel carbon black nanoparticles from 5 wt% to 1 wt% in the cathode. Therefore, the energy density of the electrode can be increased by 9% by using existing commercially available electrode materials. In lithium-ion batteries, the active materials of the cathodes typically exhibit relatively high resistivity due to their intrinsically poor electronic conductivity and the limited point contacts between their micro particles. [1][2][3][4][5][6] In addition, the active materials need to be mixed with binders to form the electrode, which insures the mechanical integrity and stability of the electrode. However, the binders are electric insulators that can further reduce the electrical conductivity of the electrode. To minimize the problem of the poor electrical conductivity of the electrode, conductive powders, such as carbon black, carbon fiber, carbon nanotube, or graphene, are added to the electrode formulation. [5][6][7][8][9][10] In the battery industry, there are at least two competing requirements for the amount of conductive additive needed: (i) high rate performance requiring a large amount of conductive additive and (ii) high energy density dictating that the amount of conductive additive be as low as possible. These two antagonistic requirements make high demands on optimizing conductive additives as the solution. 5,6,8,10 Meanwhile, the cost is always critical for the commercial application of carbon additives. Therefore, there is increasing research attention on the carbon black nanoparticles, since it is the cheapest one among a series of carbon additives. The research focuses on the impacts of their structures, the pretreatment and loading procedures on the cathodes' performances, etc. 5,6,[10][11][12][13][14] The mechanism for the electronic conduction of carbon black nanoparticles' aggregates in cathodes is believed to occur through tunneling phenomena, the probabil...