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Development of energy storage materials with high energy density to fulfill the demand of next generation batteries is a blistering topic under immense debate. The Li–O2 battery is attracting much more attention for its enhanced theoretical energy density compared to the traditional Li-ion battery. Porous oxygen-breathing catalysts, especially biomass-derived materials, could offer plenty of oxygen diffusion paths and Li2O2 formation space, which is beneficial for the Li–O2 battery. In this work, a simple method is used to prepare phosphorus doped pinecone-derived hive-like carbon (P-PHC) with a porous structure. This P-PHC as a non-noble catalyst owns unique architecture as well as active P sites, a large BET surface area, and abundant defects on the surface. Ex-situ SEM images demonstrate that the porous structure of P-PHC remains during the discharging process. EIS results reveal that P-PHC could guarantee better charge transfer as well as better O2 and Li+ diffusion. Due to the synergistic effect of higher activity from abundant defects on the surface as well as better O2 and Li+ diffusion from the unique hive-like structure, P-PHC delivers a large discharge specific capacity of 24 500 mAh g–1 at a current density of 100 mA g–1 and a durable cycling number of 205 times when operated at a specific capacity of 1 Ah g–1 under a current density of 0.5 A g–1. This work proposes a sustainable strategy of reusing wasted biomass for rechargeable batteries, which would be beneficial to the energy and environment fields.

Non-aqueous Li−O 2 batteries have aroused considerable attention because of their ultrahigh theoretical energy density, but they are severely hindered by slow cathode reaction kinetics and large overvoltages, which are closely associated with the discharge product of Li 2 O 2 . Herein, hexagonal conductive metal−organic framework nanowire arrays of nickel-hexaiminotriphenylene (Ni-HTP) with quadrilateral Ni-N 4 units are synthesized to incorporate Ru atoms into its skeleton for NiRu-HTP. The atomically dispersed Ru-N 4 sites manifest strong adsorption for the LiO 2 intermediate owing to its tunable d-band center, leading to its high local concentration around NiRu-HTP. This favors the formation of film-like Li 2 O 2 on NiRu-HTP with promoted electron transfer and ion diffusion across the cathodeelectrolyte interface, facilitating its reversible decomposition during charge. These allow the Li−O 2 battery with NiRu-HTP to deliver a remarkably reduced charge/ discharge polarization of 0.76 V and excellent cyclability. This work will enrich the design philosophy of electrocatalysts for regulation of kinetic behaviors of oxygen redox.

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Aprotic Li-O 2 batteries are a promising energy storage technology, however severe side reactions during cycles lead to their poor rechargeability. Herein, highly reactive singlet oxygen ( 1 O 2 ) is revealed to generate in both the discharging and charging processes and is deterimental to battery stability. Electron-rich triphenylamine (TPA) is demonstrated as an effective quencher in the electrolyte to mitigate 1 O 2 and its associated parasitic reactions, which has the tertiary amine and phenyl groups to manifest excellent electrochemical stability and chemical reversibility. It reacts with electrophilic 1 O 2 to form a singlet complex during cycles, and it then quickly transforms to a triplet complex through nonradiative intersystem crossing (ISC). This efficiently accelerates the conversion of 1 O 2 to the ground-state triplet oxygen to eliminate its derived side reactions, and the regeneration of TPA. These enable the Li-O 2 battery with obviously reduced overvoltages and prolonged lifetime for over 310 cycles when coupled with a RuO 2 catalyst. This work highlights the ISC mechanism to quench 1 O 2 in Li-O 2 battery.

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Solid polymer electrolytes can be used to construct solid-state lithium batteries (SSLBs) using lithium metals as the anode. However, the lifespan and safety problems of SSLBs caused by lithium dendrite growth have hindered their practical application. Here, we have designed and prepared a rigid-flexible asymmetric solid electrolyte (ASE) that is used in building SSLBs. The ASE can inhibit efficiently the growth of lithium dendrites and lead to a long cycle life of SSLBs due to the hierarchical structure of a combination of “polymer-in-ceramic” (i.e., rigid ceramic layer of Li6.4La3Zr1.4Ta0.6O12) and “LiBOB-in-polymer” (i.e., soft polymer-layer of polyethylene oxide and LiBOB components). The results demonstrated that a symmetrical battery with ASE (Li|ASE|Li) can be steadily cycled for more than 2000 h and yielded a flat plating/stripping voltage profile under a current density of 0.1 mA cm–2. As a consequence, the SSLB of LiFePO4|ASE|Li delivered a specific capacity of 155.1 mA h g–1 with a capacity retention rate up to 90.2% after 200 cycles with the Coulombic efficiency over 99.6% per cycle. This asymmetric structure combines the advantages of ceramics and polymers, providing an ingenious solution for building rigid and flexible solid electrolytes.