Rechargeable aluminum-ion batteries (AIBs) are a new generation of low-cost and large-scale electrical energy storage systems. However, AIBs suffer from a lack of reliable cathode materials with insufficient intercalation sites, poor ion-conducting channels, and poor diffusion dynamics of large chloroaluminate anions (AlCl4− and Al2Cl7−). To address these issues, surface-modified graphitic carbon materials [i.e., acid-treated expanded graphite (AEG) and base-etched graphite (BEG)] are developed as novel cathode materials for ultra-fast chargeable AIBs. AEG has more turbostratically ordered structure covered with abundant micro- to nano-sized pores on the surface structure and expanded interlayer distance (d002 = 0.3371 nm) realized by surface treatment of pristine graphite with acidic media, which can be accelerated the diffusion dynamics and efficient AlCl4− ions (de)-intercalation kinetics. The AIB system employing AEG exhibits a specific capacity of 88.6 mAh g−1 (4 A g−1) and ~ 80 mAh g−1 at an ultra-high current rate of 10 A g−1 (~ 99.1% over 10,000 cycles). BEG treated with KOH solution possesses the turbostratically disordered structure with high density of defective sites and largely expanded d-spacing (d002 = 0.3384 nm) for attracting and uptaking more AlCl4− ions with relatively shorter penetration depth. Impressively, the AIB system based on the BEG cathode delivers a high specific capacity of 110 mAh g−1 (4 A g−1) and ~ 91 mAh g−1 (~ 99.9% over 10,000 cycles at 10 A g−1). Moreover, the BEG cell has high energy and power densities of 247 Wh kg−1 and 44.5 kW kg−1. This performance is one of the best among the AIB graphitic carbon materials reported for chloroaluminate anions storage performance. This finding provides great significance for the further development of rechargeable AIBs with high energy, high power density, and exceptionally long life.

Organic carbonyl molecules have recently been investigated as redox-active electrode materials in rechargeable organic batteries (ROBs), and although redox-active polymers offer high specific energy density and tunable redox potential windows, their undesirable dissolution into aprotic electrolytes during charge/discharge cycling and their poor electronic conductivity compromised their utilization in ROBs. To overcome these challenges, we synthesized, for the first time, two 3,4:9,10-perylenetetracarboxylic dianhydride (PTCDA)-based polyimides, namely, perylenediimide-benzidine (PDI-Bz) and perylenediimide-urea (PDI-Ur), and utilized them as organic cathode materials for lithium-ion batteries and sodium-ion batteries. These cathode materials are synthesized through imidization of a non-bay-substituted PTCDA unit by using bifunctional amine compounds (i.e., benzidine and carbonyl diamine (urea)) via a simple one-step reaction. Our organic metal-ion batteries employing PDI-Bz demonstrate a high discharge capacity of 120 mAh/g (with a reversible capacity of ∼54 mAh/g) vs Li + /Li and the second discharge capacity of 111 mAh/g (∼74 mAh/g) vs Na + /Na with two discharge voltage plateaus in the range of 1.9−2.4 V. The cells retained a capacity retention of 46% vs Li + /Li and 55.2% vs Na + /Na over 50 cycles. PDI-Ur exhibits higher lithiation capacity of ∼119 mAh/g at the 14th cycling (increased discharge capacity of ∼118 mAh/g at the 25th cycling). In SIBs, PDI-Ur shows an initial discharge capacity of ∼119 mAh/g with a single discharge voltage plateau around 1.9 V vs Na + /Na and the capacity retention of ∼78.7% (∼93 mAh/g) over 50 cycles, both of which are suggesting a potential feasibility of these PTCDA-based polyimides as promising organic cathode materials for high-capacity metal-ions batteries.

Redox-active organic electrode materials are considered promising alternatives to inorganic intercalation analogs in organic metal-ion batteries. However, their poor cycling stability owing to high solubility in organic electrolytes and poor...

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