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Pyrite FeS 2 has long been used as commercial primary lithium batteries at room temperature. To achieve rechargeable FeS 2 battery, biomass-carbon@FeS 2 composites are prepared using green and renewable auricularia auricula as carbon source through the process of carbonization and sulfuration. The auricularia auricula has strong swelling characteristics to absorb aqueous solution which can effectively absorb Fe ions into its body. FeS 2 homogeneously distributed in biomass carbon matrix performs high electronic and ionic conductivity. The specific capacity of biomass-carbon@FeS 2 composites remains 850 mAh g −1 after 80 cycles at 0.5C and 700 mAh g −1 at the rate of 2C after 150 cycles. Biomass-carbon@FeS 2 composites exhibit high-rate capacity in lithium-ion battery. [ABSTRACT FROM AUTHOR]

FeS 2 nanocrystals are successfully prepared in the carbon capsules of pre-prepared hierarchical porous carbon (HPC). The absorbed Fe ions in HPC are first calcined into Fe 3 O 4 and then react with sulfur under vacuum conditions to synthesize FeS 2 . HPC, with micro-porous shells and inter-connected macro-porous carbon capsules, shows highly ionic/electrical conductivities and efficient buffer effect on the volume change of FeS 2 . FeS 2 @HPC exhibits a high specific capacity of 907 mAh·g −1 in the first cycle and remains 720 mAh·g −1 after 100 cycles at the rate of 1 C. [ABSTRACT FROM AUTHOR]

Silicon is considered as the most promising anode for advanced lithium-ion batteries (LIBs) due to the high theoretical capacity of 3579 mAh g −1 , but the complex and high-cost preparation processes have limited it's widespread applications. So given the practical application, it's all the more important that we should prepare excellent electrochemical performance anodes with large scale and low cost. Here we present a scalable synthesis for preparing the cost-effective Si/C anode enhanced by FeSi x nanoparticles (FSC) directly from the low-grade Ferrosilicon source (∼1000 $/t). The formation of the amorphous carbon layer and FeSi x nanocrystalline (FeSi & FeSi 2 ) can act as buffer layer to mechanically support the volume expansion change during cycling. The FSC anode exhibits a high initial capacity of 1489 mAh g −1 and a prolonged cycle performance with 86% capacity retention over 100 cycles at 500 mA g −1 . Moreover, the FSC anode delivers an excellent rate performance of 450 mAh g −1 at 10 A g −1 due to the enhancement of the electrical conductivity by the amorphous carbon layer and the highly conductive FeSi x nanocrystalline. This scalable and cost-effective method for preparing Si/C anode provides the promising application potentials in next generation energy storage systems. [ABSTRACT FROM AUTHOR]

Potassium ion batteries are promisingly proposed for the large cale energy storage. However, potassium with large ion radius causes severe volumetric expansion of anodes during charging, which deteriorates the rate and the cycling performances of batteries. Herein, a honeycomb-like graphene monolith with rich micropores is prepared. The monolith is further applied as the binder-free anode for potassium ion batteries. It shows the remarkable rate performance with a capacity of 180 mAh g−1 at a current density of 10 A g−1, and it can stably run for 4000 cycles at 1 A g−1. Kinetic studies and theoretical analyses reveal that the large graphitic interlayer spacing, the nitrogen doping, and the 3D network structure can significantly promote the diffusion rate, the absorption of potassium ions, as well as the transports of electrons and ions. The graphene-based potassium ion batteries can thus boost the development of renewable energies. [Display omitted] • Defect-rich monolithic graphene with high specific surface area was prepared. • Zinc-guided graphene monolith was used as a binder-free potassium-storage anode. • Large interlayer spacing, nitrogen doping and 3D network improved performances. [ABSTRACT FROM AUTHOR]