Holey graphene-wrapped porous TiNb24O62 microparticles as high-performance intercalation pseudocapacitive anode materials for lithium-ion capacitors

It is desirable to develop an energy storage system with both high energy density and high power density along with excellent cycling stability to meet practical application requirements. Lithium-ion capacitors (LICs) are very promising due to the combined merits of the high power density of electrochemical capacitors and the high energy density of batteries. However, the lack of high rate performance anode materials has been the major challenge of lithium-ion capacitors. Herein, we designed and synthesized holey graphene-wrapped porous TiNb24O62 as an anode material for lithium-ion capacitors. Pseudocapacitive storage behaviors with fast kinetics, high reversibility, and excellent cycling stability were demonstrated. The hybrid material can deliver a high capacity of 323 mAh g−1 at 0.1 A g−1, retaining 183 mAh g−1 at 10 A g−1. Coupled with a carbon nanosheet-based cathode, an LIC with an ultrahigh energy density of 103.9 Wh kg−1 was obtained, and it retained 28.9 Wh kg−1 even under a high power density of 17.9 kW kg−1 with a high capacity retention of 81.8% after 10,000 cycles. Porous microparticles wrapped in graphene offer a route to high capacity and stable energy-storage devices according to research from Singapore. Portable energy storage is vital to power mobile electronic devices and electric vehicles. Lithium ion batteries are now ubiquitous in laptops and cell phones, but the number of times they can be charged and discharged is limited. Supercapacitors offer much longer cycling stability, but lower energy density. Pooi See Lee and co-workers from Nanyang Technological University, Singapore, synthesized TiNb24O62 microparticles encapsulated by graphene for use as electrodes in lithium ion capacitors, devices that combine the advantages of both lithium ion batteries and supercapacitors. The graphene wrapped porous structure reduced the ion diffusion length and enabled faster charging and discharging. The device showed little decline in performance even after 10,000 cycles. A holey graphene-wrapped porous TiNb24O62 microparticles for ultrafast pseudocapacitive lithium storage is studied. Due to the nanoscale dimensions and hierarchically porous channels of the nanocomposite material, the hybrid material exhibits both excellent rate performance and stability. Coupling with carbon nanosheet cathode, the fabricated lithium-ion capacitor demonstrate high energy and power density as well as utralong cycling stability.