High‐Energy SWCNT Cathode for Aqueous Al‐Ion Battery Boosted by Multi‐Ion Intercalation Chemistry

Abstract

The aqueous Al‐ion battery has achieved great progress in recent years. It now shows comparable performance to that of even non‐aqueous Al‐ion batteries. However, it also shows relatively low energy output and there is limited general understanding of the mechanism behind this restriction to its practical application. Thus, the development of a high‐performance cathode material is in great demand. Herein, a high‐capacity single‐walled carbon nanotube (SWCNT) is developed as a cathode for the water‐in‐salt electrolyte‐based aqueous Al‐ion battery, which provides an ultra‐high specific capacity of 790 mAh g–1 (based on the mass of SWCNT) at a high current density of 5 A g–1 even after 1000 cycles. Moreover, the SWCNT/Al battery shows a complicated multi‐ion intercalation mechanism, where AlCl4–, Cl–, Al3+, and H+ can function at the same time, improving the battery output. Beyond recently revealed H+ and metal ion co‐intercalation, the Cl‐assisted intercalation of Al3+ ions mechanism is also studied by experimental characterization and modeling for the first time, which significantly boosts the Al3+ storage capacity. This multi‐ion intercalation mechanism combines the high‐voltage anion deintercalation and the high‐capacity cation intercalation, and thus, benefits the development and application of high‐energy Al‐ion batteries in the future.

Rechargeable Aqueous Aluminum‐Ion Battery: Progress and Outlook

“…The Al/41 m AlCl 3 /SWCNT battery exhibited a specific capacity of 790 mAh g −1 at 5 A g −1 after 1000 cycles. [54] It showed two discharge plateaus of 1.8 and 1.2 V, which correspond to the deintercalation of AlCl 4 − and Cl − -assisted cointercalation of Al 3+ / H + , respectively. Apart from that, multi-ion intercalation of AlCl 4 − , Cl − , Al 3+ , and H + has also been carefully reviewed.…”

Anode Materials for Rechargeable Aqueous Al‐Ion Batteries: Progress and Prospects

“…Leung's group further revealed the underlying mechanism. [64] They formulated a "water-in-salt" Al(NO 3 ) 3 electrolyte with HCl additive (Figure 5e). The existence of Cl À could assist the Al 3 + intercalation, resulting in a higher discharge plateau and improved performance.…”

“…Reproduced with permission. [64] Copyright 2021, Wiley-VCH. (f) EIS plots obtained for Al//Al symmetric cells with different electrolytes.…”

“…(e) CV comparison of SWCNT tested in WISÀ Al(NO 3 ) 3 and WISÀ Al(NO 3 ) 3 with HCl additive at a series of scan rates. Reproduced with permission [64]. Copyright 2021, Wiley-VCH.…”

A lamellar V2O3@C composite for aluminium-ion batteries displaying long cycle life and low-temperature tolerance

“…For example, Pan et al developed a high-capacity single-walled carbon nanotube (SWCNT) as a cathode for Al-ion batteries, which delivered 790 mA h g −1 (based on the mass of SWCNT) at a current density of 5 A g −1 . 9 Lin et al reported amorphous anion-rich titanium polysulfides (a-TiS x , x = 2, 3 and 4) (AATPs) with a high concentration of defects. 10 The AATP cathodes, especially a-TiS 4 , achieved 206 mA h g −1 over 1000 cycles.…”