Sequential Coordination Templating and Catalytic Carbon Coating via a Single Manganese Modifier for High-Performance...

In hard carbon anodes, initial Coulombic efficiency (ICE) and reversible capacity are difficult to enhance simultaneously. This work employs manganese acetate as a single modifier coupled with methane CVD, driving two sequential mechanisms in one-step pyrolysis: at the low-temperature stage, Mn²⁺ coordinates with oxygen-containing functional groups at carbon edge sites to form C─O─MnO bonds, inducing ordered carbon-layer rearrangement; at the high-temperature stage, these coordination bonds dissociate, and in situ-generated MnO nanoparticles (∼18 nm) catalyze CH₄ decomposition, depositing a dense carbon coating ∼7.5 nm in thickness. Compared with the pristine hard carbon (0Mn-900), the optimized 0.1Mn-CVD1h boosts the ICE from 58.97% to 81.31% and the reversible capacity from 288.31 to 369.52 mAh g^-1, with 96.35% retention after 300 cycles at 1 A g^-1. A 500 mAh pouch-type full cell with an LiNi_0.6Co_0.2Mn_0.2O₂ (NCM622) cathode retains 85.14% capacity at 30C, 74.62% at -30°C, and 74.36% after 10 000 cycles at 5C. This work demonstrates that the sequential dual utilization of a single modifier, from coordination template to catalytic center, offers a promising pathway toward reconciling the trade-off between capacity and ICE in hard carbon anodes.