Flexible lithium–CO2 battery with ultrahigh capacity and stable cycling

Abstract

Carbon dioxide is understood as a major contributor to the greenhouse effect. The search for an effective and efficient method for CO₂ capture and utilization has become a priority task on a global scale. For Mars exploration missions, the ability to use the CO₂ in the atmosphere (96%) could offer great benefits in terms of energy storage. The Li–CO₂ battery is considered a promising platform for CO₂ capture, with its ability to utilize the captured CO₂ for energy storage. However, the Li–CO₂ battery still suffers various inadequacies, including the slow kinetics of CO₂ reduction, the high charge/discharge hysteresis, the ultra-stable discharge product, and the slow transport of CO₂ gas and electrolyte. In this work, we introduce a high-capacity, long-life Li–CO₂ battery based on a flexible wood cathode architecture. Mother nature has produced the most efficient ion and gas transport architectural system in the form of wood. The unique channel structure of the wood-based cathode separates the transport of CO₂ and the electrolyte into specific pathways, leading to facilitated transport. The improvements in mass transport, combined with faster kinetics as a result of the use of Ru nanocatalyst supported on carbon nanotubes that reside in the microchannels, contribute to substantially improved electrochemical performance. Stable cycling for over 200 cycles with both a low overpotential and an ultrahigh discharge capacity of 11 mA h cm⁻² is achieved with the flexible wood-based Li–CO₂ battery. Such a long cycle life and high capacity is unprecedented for a Li–CO₂ battery. Additionally, the cathode exhibits excellent mechanical flexibility imparted by the flexible wood scaffold, holding great promise for wearable device applications. The high capacity and the long cycle life make the flexible wood cathode Li–CO₂ battery a promising candidate for combining CO₂ capture and utilization.