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

Abstract

Despite possessing high theoretical energy density, rechargeable Li-O-2 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 under-lining the promise of LSPR-generated hot-carriers on the O-2 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 similar to 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.