Acrylonitrile copolymer/graphene skinned cathode for long cycle life rechargeable hybrid aqueous batteries at high-temperature

Biomolecule-guided cation regulation for dendrite-free metal anodes

Lithium (Li) or zinc (Zn) metal anodes have attracted interest for battery research due to their high theoretical capacities and low redox potentials. However, uncontrollable dendrite growth, especially under high current (>4 mA cm^-2), precludes reversable cycling in Li or Zn metal batteries with a high-loading (>4 mAh cm^-2), precludes reversable cycling in Li or Zn metal batteries with high-loading (>4 mAh cm^-2) cathode. We report a cation regulation mechanism to address this failure. Collagen hydrolysate coated on absorbed glass mat (CH@AGM) can simultaneously induce a deionization shock inside the separator and spread cations on the anode to promote uniform electrodeposition. Employing 24 mAh cm^-2 cathodes, Li and Zn metal batteries with CH@AGM delivered 600 cycles with a Coulombic efficiency of 99.7%. In comparison, pristine Li and Zn metal batteries only survive for 10 and 100 cycles, respectively. This approach enabled 400 cycles in a 200 Ah-class Zn metal battery, which suggests a scalable method to achieve dendrite-free anodes in various batteries.

Tuning Microstructures of Graphene to Improve Power Capability of Rechargeable Hybrid Aqueous Batteries

Low conductivity and structural degradation of LiMn₂O₄ lead to poor power capability and severe capacity fading of hybrid aqueous Zn/LiMn₂O₄ battery. Here, we propose an effective strategy by tuning the microstructures of graphene to optimize its electrical and interfacial properties and electrode dynamics of LiMn₂O₄/graphene cathodes, which successfully prompt significant improvements in electrical conductivity and structural stability, thus essentially leading to a promising electrochemical performance. More importantly, it reveals different electrochemical properties prompted by different conductivity, which mainly depends on the microstructures of graphene. This dependence is due to the influence of electronic channels and conductive paths on the conductivity of LiMn₂O₄/graphene electrodes. A well-designed mesoporous graphene composed of about two graphene-layers exhibits an excellent high-rate performance; even after 300 cycles, a highly reversible capacity of 75 mAh g^-1 is retained at 4C rate. The results of this study suggest that the structural tuning of electronic channels of graphene can be used as an effective means to improve the performance of LiMn₂O₄ cathodes in hybrid aqueous batteries.

Self-Assembly of Free-Standing LiMn₂O₄-Graphene Flexible Film for High-Performance Rechargeable Hybrid Aqueous Battery

A novel LiMn₂O₄-graphene flexible film is successfully prepared by facile vacuum filtration technique. LiMn₂O₄ nanowires with diameters of 50–100 nm are distributed homogeneously on graphene sheet matrix. Used as cathode in rechargeable hybrid aqueous batteries, the LiMn₂O₄-graphene film exhibits enhanced electrochemical performance in comparison to LiMn₂O₄-graphene powder. The LiMn₂O₄-graphene film shows stable 13.0 mAh g⁻¹ discharge capacity after 200 cycles at 1.0 C, benefitting from the presence of graphene with strong conductivity and large pore area in this free-standing film. This synthetic strategy for a free-standing film can provide a new avenue for other flexible materials and binder-free electrodes.