Selective Surface Functionalization of Carbon Black by Planar DBD Plasma for Tailored Lithium-Ion Battery Performance

Selective construction of specific oxygen-containing functional groups (OFGs) on carbon surfaces-while strictly preserving skeletal integrity, eliminating exogenous contamination, and ensuring process reproducibility-remains a long-standing challenge in surface science. We developed a planar dielectric barrier discharge (DBD) reactor sustaining homogeneous atmospheric-pressure discharge (σ ≈ 1) under carbon nanopowder loading, completing treatment within 4 min at 2.3 kWh kg-1, substantially below conventional plasma oxidation systems. Through systematic modulation of O2/Ar feed composition under direct in-plasma exposure, hydroxyl, carboxyl, and carbonyl groups were selectively enriched on acetylene black, achieving selectivities of 74.07, 74.22, and 61.71%, respectively (coefficient of variation < 16%). Invariant ID/IG, Lc, d002, and pore size distributions, together with XPS analysis, collectively confirmed the absence of structural damage, pore alteration, or metallic/acidic contamination; functionalized samples additionally exhibited markedly enhanced colloidal dispersibility. Zero-dimensional plasma chemical kinetics simulations revealed that OFG selectivity originates from a concentration-dependent competition between Ar*- and Ar+-driven defunctionalization and the temporal evolution of reactive oxygen species. When employed as conductive additives in lithium-ion batteries, OFG-tailored carbon blacks delivered targeted electrochemical enhancements, with rate capability improved by up to 42.3% and low-rate capacity increased by ∼30%, validating the efficacy of directed surface chemistry in modulating electrochemical behavior. Post-cycling EIS analysis revealed that the OFGs modulate the CEI thickness, uniformity, and ionic resistance at the molecular scale, directly explaining the observed trade-off between rate capability and cycling stability. This work presents an energy-efficient, contamination-free DBD plasma strategy for selective carbon surface modification, offering a low-cost and generalizable framework for performance-oriented lithium-ion battery optimization.