For the first time, it is demonstrated that nanoscale HfO₂ surface passivation layers formed by atomic layer deposition (ALD) significantly improve the performance of Li ion batteries with SnO₂‐based anodes. Specifically, the measured battery capacity at a current density of 150 mAg⁻¹ after 100 cycles is 548 and 853 mAhg⁻¹ for the uncoated and HfO₂‐coated anodes, respectively. Material analysis reveals that the HfO₂ layers are amorphous in nature and conformably coat the SnO₂‐based anodes. In addition, the analysis reveals that ALD HfO₂ not only protects the SnO₂‐based anodes from irreversible reactions with the electrolyte and buffers its volume change, but also chemically interacts with the SnO₂ anodes to increase battery capacity, despite the fact that HfO₂ is itself electrochemically inactive. The amorphous nature of HfO₂ is an important factor in explaining its behavior, as it still allows sufficient Li diffusion for an efficient anode lithiation/delithiation process to occur, leading to higher battery capacity.