Dual Layer Coating Strategy Utilizing N-doped Carbon and Reduced Graphene Oxide for High-Performance LiFePO 4 Cathode Material

Biomass-Derived Carbon Utilization for Electrochemical Energy Enhancement in Lithium-Ion Batteries

Cathodes made of LiFePO4 (LFP) offer numerous benefits including being non-toxic, eco-friendly, and affordable. The distinctive olivine structure of LFP cathodes contributes to their electrochemical stability. Nonetheless, this structure is also the cause of their low ionic and electronic conductivity. To enhance these limitations, an uncomplicated approach has been effectively employed. A straightforward solid-state synthesis technique is used to apply a coating of biomass from potato peels to the LFP cathode, boosting its electrochemical capabilities. Potato peels contain pyridinic and pyrrolic nitrogen, which are conducive to ionic and electronic movement and facilitate pathways for lithium-ion and electron transfer, thus elevating electrochemical performance. When coated with nitrogen-doped carbon derived from potato peel biomass (PPNC@LFP), the LFP cathode demonstrates an improved discharge capacity of 150.39 mAh g-1 at a 0.1 C-rate and 112.83 mAh g-1 at a 1.0 C-rate, in contrast to the uncoated LFP which shows capacities of 141.34 mAh g-1 and 97.72 mAh g-1 at the same rates, respectively.

Effect of Conductive Material Morphology on Spherical Lithium Iron Phosphate

As an integral part of a lithium-ion battery, carbonaceous conductive agents have an important impact on the performance of the battery. Carbon sources (e.g., granular Super-P and KS-15, linear carbon nanotube, layered graphene) with different morphologies were added into the battery as conductive agents, and the effects of their morphologies on the electrochemical performance and processability of spherical lithium iron phosphate were investigated. The results show that the linear carbon nanotube and layered graphene enable conductive agents to efficiently connect to the cathode materials, which contribute to improving the stability of the electrode-slurry and reducing the internal resistance of cells. The batteries using nanotubes and graphene as conductive agents showed weaker battery internal resistance, excellent electrochemical performance and low-temperature dischargeability. The battery using carbon nanotube as the conductive agent had the best overall performance with an internal resistance of 30 mΩ. The battery using a carbon nanotube as the conductive agent exhibited better low-temperature performance, whose discharge capacity at -20 °C can reach 343 mAh, corresponding to 65.0% of that at 25 °C.

Electrochemically exfoliated graphene as a novel microwave susceptor: the ultrafast microwave-assisted synthesis of carbon-coated silicon-graphene film as a lithium-ion battery anode

Graphene nanocomposites have attracted much attention in many applications due to their superior properties. However, preparing graphene nanocomposites requires a time-consuming thermal treatment to reduce the graphene or synthesize nanomaterials, in most cases. We present an ultrafast synthesis of a carbon-coated silicon-graphene nanocomposite using a commercial microwave system. Electrochemically exfoliated graphene is used as a novel microwave susceptor to deliver efficient microwave energy conversion. Unlike graphene oxide, it does not require a time-consuming pre-thermal reduction or toxic chemical reduction to absorb microwave radiation efficiently. A carbon-coated silicon nanoparticle-electrochemically exfoliated graphene nanocomposite film was prepared by a few seconds' microwave irradiation. The sp² domains of graphene absorb microwave radiation and generate heat to simultaneously reduce the graphene and carbonize the polydopamine carbon precursor. The as-prepared N-doped carbon-coated silicon-graphene film was used as a lithium-ion battery anode. The N-doped carbon coating decreases the contact resistance between silicon nanoparticles and graphene provides a wide range conductive network. Consequently, it exhibited a reversible capacity of 1744 mA h g^-1 at a current density of 0.1 A g^-1 and 662 mA h g^-1 at 1.0 A g^-1 after 200 cycles. This method can potentially be a general approach to prepare various graphene nanocomposites in an extremely short time.