Jiabin Xi

Ultrafast all-climate aluminum-graphene battery with quarter-million cycle life

Trihigh tricontinuous graphene cathode enables a 1.1 s charge, 250,000 cycle life, wide temperature range Al-ion battery. Rechargeable aluminum-ion batteries are promising in high-power density but still face critical challenges of limited lifetime, rate capability, and cathodic capacity. We design a “trihigh tricontinuous” (3H3C) graphene film cathode with features of high quality, orientation, and channeling for local structures (3H) and continuous electron-conducting matrix, ion-diffusion highway, and electroactive mass for the whole electrode (3C). Such a cathode retains high specific capacity of around 120 mAh g−1 at ultrahigh current density of 400 A g−1 (charged in 1.1 s) with 91.7% retention after 250,000 cycles, surpassing all the previous batteries in terms of rate capability and cycle life. The assembled aluminum-graphene battery works well within a wide temperature range of −40 to 120°C with remarkable flexibility bearing 10,000 times of folding, promising for all-climate wearable energy devices. This design opens an avenue for a future super-batteries.

Superconducting Continuous Graphene Fibers via Calcium Intercalation

Superconductors are important materials in the field of low-temperature magnet applications and long-distance electrical power transmission systems. Besides metal-based superconducting materials, carbon-based superconductors have attracted considerable attention in recent years. Up to now, five allotropes of carbon, including diamond, graphite, C60, CNTs, and graphene, have been reported to show superconducting behavior. However, most of the carbon-based superconductors are limited to small size and discontinuous phases, which inevitably hinders further application in macroscopic form. Therefore, it raises a question of whether continuously carbon-based superconducting wires could be accessed, which is of vital importance from viewpoints of fundamental research and practical application. Here, inspired by superconducting graphene, we successfully fabricated flexible graphene-based superconducting fibers via a well-established calcium (Ca) intercalation strategy. The resultant Ca-intercalated graphene fiber (Ca-GF) shows a superconducting transition at ∼11 K, which is almost 2 orders of magnitude higher than that of early reported alkali metal intercalated graphite and comparable to that of commercial superconducting NbTi wire. The combination of lightness and easy scalability makes Ca-GF highly promising as a lightweight superconducting wire.

Sheet Collapsing Approach for Rubber-like Graphene Papers

Understanding and modulating the conformation of graphene are pivotal in designing graphene macroscopic materials. Here, we revealed the sheet collapsing behavior of graphene oxide (GO) sheets by poor solvents in an analogy with linear macromolecules. Triggered by poor solvents, extended GO sheets in good solvents can collapse to hierarchically wrinkled conformations. The collapsing behavior of GO enabled the fabrication of amorphous self-standing GO and graphene papers with rich hierarchical wrinkles and folds over mutliple size scales. The collapsed GO and graphene papers had a rubber-like mechanical behavior with viscoelasticity. By our collapsing method, GO and graphene self-standing papers were designed to be stiff with high modulus or to become soft with low modulus of 100 MPa at a remarkably large breakage elongation up to 23%. Our philosophy of treating graphene as a 2D polymer enables the efficient control of molecular conformations of graphene and other 2D polymers and the design of macroscopic materials of 2D nanomaterials as in the polymer industry.

Multifunctional Bicontinuous Composite Foams with Ultralow Percolation Thresholds

Integrating ultralight weight and strong mechanical performance into cellular monolith is a challenge unresolved yet. Here, we propose a skeleton-assisted self-assembly method to design ultralight bicontinuous composite foams (BCCFs) with high mechanical robustness and ultralow percolation thresholds. Polymer foam was employed as the skeleton to support assembled graphene networks, forming BCCFs with a high tensile strength (∼80 kPa) and breakage elongation (>22.2%). The paraffin and poly(dimethylsiloxane) infiltrated BCCFs show a record low percolation threshold of 0.006 vol % and a relatively high electrical conductivity of 0.81 S m-1 at a low graphene content of 0.216 vol %. The BCCFs demonstrate high and adjustable microwave-absorbing (MA) properties. The effective absorption bandwidth (reflection loss ≤ -10 dB) for BCCFs with a low graphene loading of 3.4 mg cm-3 achieves 9.0 GHz at a thickness of 4 mm, and it further covers 13.6 GHz considering the adjustability of preferred absorption band. The BCCFs with an extremely low graphene load of 0.14 mg cm-3 were further used for durable and efficient oil adsorption, which can adsorb >60 times their own weight. The facile fabrication of bicontinuous composite foams opens the avenue for practical applications of high-strength, multifunctional, and productive graphene-based foams.