No abstract

Incorporating redox active units in a 3D porous network is an encouraging strategy to enhance electrochemical performance of organic electrode materials. Herein, a new hybrid composed by phenazine-based conjugated microporous polymer (IEP-27-SR, stand for IMDEA Energy Polymer number 27) and singlewalled carbon nanotubes (SWCNTs) and graphene oxide (RGO) is synthesized, fully characterized and tested electrochemically in different aqueous electrolyte conditions, i. e., at various pH values (1-12) and also with different charge carriers (H + in acidic, and Li + , Na + , K + in neutral and alkaline electrolytes).Although the IEP-27-SR is found to be very versatile showing very good electrochemistry both in alkaline and acidic solution, it exhibits best specific capacity, redox kinetics and cycle stability in acidic electrolyte. Then encouragingly, when IEP-27-SR is combined with an activated carbon (AC) counter electrode to construct a proof-of-the-concept device, the IEP-27-SR//AC demonstrates high specific capacity (168 mAh g À 1 at 2 C), impressive rate performance (96 mAh g À 1 at 60 C) and ultralong cycle stability (76 % capacity retention over 28800 cycles at 10 C; 2690 h) in 1 M H 2 SO 4 .

Energy‐storage materials can be assembled directly on the electrodes of a battery using electrochemical methods, this allowing sequential deposition, high structural control, and low cost. Here, a two‐step approach combining electrophoretic deposition (EPD) and cathodic electrodeposition (CED) is demonstrated to fabricate multilayer hierarchical electrodes of reduced graphene oxide (rGO) and mixed transition metal sulfides (NiCoMnSx). The process is performed directly on conductive electrodes applying a small electric bias to electro‐deposit rGO and NiCoMnSx in alternated cycles, yielding an ideal porous network and a continuous path for transport of ions and electrons. A fully rechargeable alkaline battery (RAB) assembled with such electrodes gives maximum energy density of 97.2 Wh kg−1 and maximum power density of 3.1 kW kg−1, calculated on the total mass of active materials, and outstanding cycling stability (retention 72% after 7000 charge/discharge cycles at 10 A g−1). When the total electrode mass of the cell is considered, the authors achieve an unprecedented gravimetric energy density of 68.5 Wh kg−1, sevenfold higher than that of typical commercial supercapacitors, higher than that of Ni/Cd or lead–acid Batteries and similar to Ni–MH Batteries. The approach can be used to assemble multilayer composite structures on arbitrary electrode shapes.

One of the possible solutions to circumvent the sluggish kinetics, low capacity, and poor integrity of inorganic cathodes commonly used in rechargeable aluminium batteries (RABs), is the use of redox-active...