Polycyclic Aromatic Hydrocarbons as a New Class of Promising Cathode Materials for Aluminum‐Ion Batteries

Abstract

As an emerging post‐lithium battery technology, aluminum ion batteries (AIBs) have the advantages of large Al reserves and high safety, and have great potential to be applied to power grid energy storage. But current graphite cathode materials are limited in charge storage capacity due to the formation of stage‐4 graphite‐intercalated compounds (GICs) in the fully charged state. Herein, we propose a new type of cathode materials for AIBs, namely polycyclic aromatic hydrocarbons (PAHs), which resemble graphite in terms of the large conjugated π bond, but do not form GICs in the charge process. Quantum chemistry calculations show that PAHs can bind AlCl4− through the interaction between the conjugated π bond in the PAHs and AlCl4−, forming on‐plane interactions. The theoretical specific capacity of PAHs is negatively correlated with the number of benzene rings in the PAHs. Then, under the guidance of theoretical calculations, anthracene, a three‐ring PAH, was evaluated as a cathode material for AIBs. Electrochemical measurements show that anthracene has a high specific capacity of 157 mAh g−1 (at 100 mA g−1) and still maintains a specific capacity of 130 mAh g−1 after 800 cycles. This work provides a feasible “theory guides practice” research model for the development of energy storage materials, and also provides a new class of promising cathode materials for AIBs.

Phenoxazine Polymer‐based p‐type Positive Electrode for Aluminum‐ion Batteries with Ultra‐long Cycle Life

“…The galvanostatic charge/discharge curves of AIBs with PX and PVBPX display two distinct discharge voltage plateaus at 1.0 V and 1.7 V (Figure 2c), which are consistent with the results of the CV curves. The PVPBX electrode delivers a discharge capacity of 133 mAh g −1 at a current density of 0.2 A g −1 , and this value is larger than those of the reported p‐type organic positive electrodes for Al‐ion batteries [15, 18] . The high discharge capacity is mainly attributed to the −N− and −O− dual active sites in the molecular structure.…”

“…If b value is 0.5, it indicates that the charge/discharge process is controlled by ion diffusion. If b value is 1.0, the electrochemical behavior is dominated by surface capacitance [18] . According to the log( i ) versus log( v ) plot in Figure 3b, the calculated b values corresponding to the four peaks O1, O2, R1, and R2 are 0.849, 0.765, 0.895, and 0.904, respectively.…”

“…The high discharge capacity is mainly attributed to the −N− and −O− dual active sites in the molecular structure. Noticeably, the first coulombic efficiency of PVBPX is only 83 %, which is related to the formation of solid electrolyte interface [18, 19] . The rate capability of PVBPX and PX electrodes at various current densities from 0.2 to 10 A g −1 are compared and displayed in Figure 2d.…”

Rational Design Strategy of Novel Energy Storage Systems: Toward High‐Performance Rechargeable Magnesium Batteries

“…[10,11] Compared to monovalent ions (Na + and K + ), [12,13] batteries based on multivalent ions such as Mg 2+ , Ca 2+ , Zn 2+ , and Al 3+ show priority in providing higher energy density (Figure 1). [14][15][16][17][18][19][20][21][22][23][24] Among these alternative candidates, rechargeable magnesium batteries (RMBs), including Mg metal batteries and Mg-ion batteries with non-Mg anode, have attracted increasing attention owing to their merits of high theoretical volumetric capacity (3833 mAh cm −3 ), abundant Mg resources, small ionic radius (0.72 Å), dendrite-free deposition behavior, moderate redox potential, etc. [25][26][27][28][29] Similar to those of LIBs, the configurations of conventional RMBs are also composed of cathode material, anode material, and electrolyte as the core composition, and the working mechanism also follows the "rocking-chair" principle, utilizing Mg 2+ instead of Li + .…”

“…[ 10,11 ] Compared to monovalent ions (Na + and K + ), [ 12,13 ] batteries based on multivalent ions such as Mg 2+ , Ca 2+ , Zn 2+ , and Al 3+ show priority in providing higher energy density ( Figure ). [ 14–24 ] Among these alternative candidates, rechargeable magnesium batteries (RMBs), including Mg metal batteries and Mg‐ion batteries with non‐Mg anode, have attracted increasing attention owing to their merits of high theoretical volumetric capacity (3833 mAh cm −3 ), abundant Mg resources, small ionic radius (0.72 Å), dendrite‐free deposition behavior, moderate redox potential, etc. [ 25–29 ]…”