Disentangling plasmonic and catalytic effects in a practical plasmon-enhanced Lithium–Oxygen battery

Despite possessing high theoretical energy density, rechargeable Li–O₂ batteries face critical drawbacks towards commercialization. In line with recent attempts to integrate solar energy exploitation in high-energy storage, here we investigate the promise of plasmonic materials with unique light-interacting properties (localized surface plasmon resonance, LSPR) and emerging application in catalysis. Au nanoparticles (NPs) at increasing contents/sizes are incorporated on conventional Ketjen Black cathodes, with preliminary half-cell measurements underlining the promise of LSPR-generated hot-carriers on the O₂ electrochemistry. The illuminated battery with facile Li₂O₂ formation/decomposition, small Li₂O₂ particles, and suppressed carboxylate side-products unlocks a round-trip efficiency boost from 75.2 to 80.2% (first cycle) and a ∼1.2-fold full capacity enhancement. Even more remarkably, with continuous cycling (30 cycles), a 680 mV-overpotential suppression is here reported. Comparatively, dark conditions reveal negligible Au-driven catalytic effects, whereas LSPR-induced local heat effects are ruled out upon meticulous assessment of the product selectivity in cells at increasing temperatures. These outstanding efficiencies are ensured even with larger particles (5–100 nm), as corroborated by corresponding galvanostatic profiles and finite-difference time-domain simulations, pinpointing the practicality of our cathodes towards scale-up. This contribution is the first to disentangle catalytic effects and plasmon relaxation pathways over practical carbon-based cathodes for high-energy storage.