High surface area porous carbon frameworks exhibit potential advantages over crystalline graphite as an electrochemical energy storage material owing to the possibility of faster ion transport and up ...to double the ion capacity, assuming a surface-based mechanism of storage. When detrimental surface-related effects such as irreversible capacity loss due to interphase formation (known as solid-electrolyte interphase, SEI) can be mitigated or altogether avoided, the greatest advantage can be achieved by maximizing the gravimetric and volumetric surface area and by tailoring the porosity to accommodate the relevant ion species. We investigate this concept by employing zeolite-templated carbon (ZTC) as the cathode in an aluminum battery based on a chloroaluminate ionic liquid electrolyte. Its ultrahigh surface area and dense, conductive network of homogeneous channels (12 Å in width) render ZTC suitable for the fast, dense storage of AlCl4 – ions (6 Å in ionic diameter). With aluminum as the anode, full cells were prepared which simultaneously exhibited both high specific energy (up to 64 Wh kg–1, 30 Wh L–1) and specific power (up to 290 W kg–1, 93 W L–1), highly stable cycling performance, and complete reversibility within the potential range of 0.01–2.20 V.
The quest for cost‐effective and TWh‐scale stationary energy storage systems has caused a surge of research on novel post‐Li‐ion batteries that consist solely of abundant chemical elements. ...Nonaqueous Al batteries, inter alia, are appealing as an inexpensive electrochemical technology owing to the high natural abundance of aluminum. A critical assessment of the literature on Al batteries, however, points to numerous misconceptions in this field. The latter is primarily linked to the false assessment of the charge storage redox reactions occurring upon cycling of Al batteries. To ensure the constructive progress of Al batteries, in this essay, the current scientific understanding of the operational mechanisms of two commonly studied Al battery systems, Al‐ion and Al dual‐ion batteries are summarized. Furthermore, the main pitfalls in interpretation and reporting of the electrochemical performance of Al cathode materials and cell‐level energy densities of Al batteries are clarified along with core challenges currently limiting their development. Toward this end, the subject of the charge storage balancing of Al dual‐ion batteries is discussed.
This essay summarizes the current scientific understanding of operational mechanisms of the two most commonly studied Al battery systems, as Al‐ion and Al dual‐ion batteries. Furthermore, it outlines the main pitfalls in interpretation and reporting of the electrochemical performance of Al cathode materials and cell‐level energy densities of Al batteries along with the core challenges currently limiting their development.
At present, rechargeable batteries composed of sodium, magnesium and aluminum are gaining attention as potentially less toxic and more economical alternatives to lithium-ion batteries. From this ...perspective, the last two decades have seen a surge of reports on various anodes and cathodes for post-lithium-ion batteries, including sodium-, magnesium-, and aluminum-ion batteries. Moreover, the new electrochemical concept of dual-ion batteries, such as magnesium-sodium and aluminum-graphite dual-ion batteries, has recently attracted considerable attention. In this focus article, the operational mechanisms of post-lithium-ion batteries are discussed and compared with lithium-ion technology, along with core challenges currently limiting their development and benefits of their practical deployment.
Post-Li-ion batteries based on Na, Mg, and Al offer substantial electrochemical and economic advantages in comparison with Li-ion batteries.
Nonaqueous, ionic liquid-based aluminum chloride–graphite batteries (AlCl3–GBs) are a highly promising post-Li-ion technology for low-cost and large-scale storage of electricity because these ...batteries feature exclusively highly abundant chemical elements and simple fabrication methods. In this work, we demonstrate that synthetic kish graphite, which is a byproduct of steelmaking, can be used as a cathode in AlCl3–GB and exhibits high capacities of ≤142 mAh g–1. The comprehensive characterization of kish graphite flakes and other forms of graphite by X-ray diffraction, Raman spectroscopy, and Brunauer–Emmett–Teller surface area analysis provides solid evidence that the exceptional electrochemical behavior of kish graphite flakes is mainly determined by the high structural order of carbon atoms, a low level of defects, and a unique “crater morphology”. In view of the nonrocking chair operation mechanism of AlCl3–GB, we have tested the achievable energy densities as a function of the composition of chloroaluminate ionic liquid (AlCl3 content) and have obtained energy densities of up to 65 Wh kg–1. In addition, the kish graphite flakes can rapidly charge and discharge, offering high power densities of up to 4363 W kg–1.
Graphite dual-ion batteries represent a potential battery concept for large-scale stationary storage of electricity, especially when constructed free of lithium and other chemical elements with ...limited natural reserves. Owing to their non-rocking-chair operation mechanism, however, the practical deployment of graphite dual-ion batteries is inherently limited by the need for large quantities of electrolyte solutions as reservoirs of all ions that are needed for complete charge and discharge of the electrodes. Thus far, lithium-free graphite dual-ion batteries have employed moderately concentrated electrolyte solutions (0.3-1 M), resulting in rather low cell-level energy densities of 20-70 Wh kg
. In this work, we present a lithium-free graphite dual-ion battery utilizing a highly concentrated electrolyte solution of 5 M potassium bis(fluorosulfonyl)imide in alkyl carbonates. The resultant battery offers an energy density of 207 Wh kg
, along with a high energy efficiency of 89% and an average discharge voltage of 4.7 V.
Replacement of Li-ion liquid-state electrolytes by solid-state counterparts in a Li-ion battery (LIB) is a major research objective as well as an urgent priority for the industry, as it enables the ...use of a Li metal anode and provides new opportunities to realize safe, non-flammable, and temperature-resilient batteries. Among the plethora of solid-state electrolytes (SSEs) investigated, garnet-type Li-ion electrolytes based on cubic Li
La
Zr
O
(LLZO) are considered the most appealing candidates for the development of future solid-state batteries because of their low electronic conductivity of ca. 10
S cm
(RT) and a wide electrochemical operation window of 0-6 V vs. Li
/Li. However, high LLZO density (5.1 g cm
) and its lower level of Li-ion conductivity (up to 1 mS cm
at RT) compared to liquid electrolytes (1.28 g cm
; ca. 10 mS cm
at RT) still raise the question as to the feasibility of using solely LLZO as an electrolyte for achieving competitive energy and power densities. In this work, we analyzed the energy densities of Li-garnet all-solid-state batteries based solely on LLZO SSE by modeling their Ragone plots using LiCoO
as the model cathode material. This assessment allowed us to identify values of the LLZO thickness, cathode areal capacity, and LLZO content in the solid-state cathode required to match the energy density of conventional lithium-ion batteries (ca. 180 Wh kg
and 497 Wh L
) at the power densities of 200 W kg
and 600 W L
, corresponding to ca. 1 h of battery discharge time (1C). We then discuss key challenges in the practical deployment of LLZO SSE in the fabrication of Li-garnet all-solid-state batteries.
Rechargeable graphite dual‐ion batteries (GDIBs) have attracted the attention of electrochemists and material scientists in recent years due to their low cost and high‐performance metrics, such as ...high power density (≈3–175 kW kg−1), energy efficiency (≈80–90%), long cycling life, and high energy density (up to 200 Wh kg−1), suited for grid‐level stationary storage of electricity. The key feature of GDIBs is the exploitation of the reversible oxidation of the graphite network with concomitant and highly efficient intercalation/deintercalation of bulky anionic species between graphene layers. In this review, historical and current research aspects of GDIBs are discussed, along with key challenges in their development and practical deployment. Specific emphasis is given to the operational mechanism of GDIBs and to unbiased and correct reporting of theoretical cell‐level energy densities.
This progress report reviews the recent progress in rechargeable graphite dual‐ion batteries, covering the topic of energy density calculations and emphasizing the importance of correct reporting of their performance metrics. Furthermore, it outlines factors governing the electrochemical performance of graphite cathodes in dual‐ion batteries such as graphite structure, morphology, and particle size.
The pressing need for low‐cost and large‐scale stationary storage of electricity has led to a new wave of research on novel batteries made entirely of components that have high natural abundances and ...are easy to manufacture. One example of such an anode–electrolyte–cathode architecture comprises metallic aluminum, AlCl3:EMImCl (1‐ethyl‐3‐methylimidazolium chloride) ionic liquid and graphite. Various forms of synthetic and natural graphite cathodes have been tested in recent years in this context. Here, a new type of compelling cathode based on inexpensive pyrene polymers is demonstrated. During charging, the condensed aromatic rings of these polymers are oxidized, which is accompanied by the uptake of aluminum tetrachloride anions (AlCl4−) from the chloroaluminate ionic liquid. Discharge is the fast inverse process of reduction and the release of AlCl4−. The electrochemical properties of the polypyrenes can be fine‐tuned by the appropriate chemical derivatization. This process is showcased here by poly(nitropyrene‐co‐pyrene), which has a storage capacity of 100 mAh g−1, higher than the neat polypyrene (70 mAh g−1) or crystalline pyrene (20 mAh g−1), at a high discharge voltage (≈1.7 V), energy efficiency (≈86%), and cyclic stability (at least 1000 cycles).
Pyrene‐based polymers are demonstrated as high‐performance cathode materials for aluminum batteries delivering capacities of up to 100 mAh g−1 at an average voltage of 1.7 V for at least 1000 cycles.
Solid-state Li-ion batteries based on Li-garnet Li
7
La
3
Zr
2
O
12
(LLZO) electrolyte have seen rapid advances in recent years. These solid-state systems are poised to address the urgent need for ...safe, non-flammable, and temperature-tolerant energy storage batteries that concomitantly possess improved energy densities and the cycle life as compared to conventional liquid-electrolyte-based counterparts. In this vision article, we review present research pursuits and discuss the limitations in the employment of LLZO solid-state electrolyte (SSE) for solid-state Li-ion batteries. Particular emphasis is given to the discussion of pros and cons of current methodologies in the fabrication of solid-state cathodes, LLZO SSE, and Li metal anode layers. Furthermore, we discuss the contributions of the LLZO thickness, cathode areal capacity, and LLZO content in the solid-state cathode on the energy density of Li-garnet solid-state batteries, summarizing their required values for matching the energy densities of conventional Li-ion systems. Finally, we highlight challenges that must be addressed in the move towards eventual commercialization of Li-garnet solid-state batteries.
The quest for low-cost and large-scale stationary storage of electricity has led to a surge of reports on novel batteries comprising exclusively highly abundant chemical elements. Aluminum-based ...systems, inter alia, are appealing because of the safety and affordability of aluminum anodes. In this work, we examined the recently proposed aluminum–ionic liquid–graphite architecture. Using 27Al nuclear magnetic resonance, we confirmed that AlCl4 – acts as an intercalating species. Although previous studies have focused on graphitic cathodes, we analyzed the practicality of achievable energy densities and found that the AlCl3-based ionic liquid is a capacity-limiting anode material. By focusing on both the graphitic cathode and the AlCl3-based anode, we improved the overall energy density. First, high cathodic capacities of ≤150 mAh g–1 and energy efficiencies of 90% at high electrode loadings of at least 10 mg cm–2 were obtained with natural, highly crystalline graphite flakes, which were subjected to minimal mechanical processing. Second, the AlCl3 content in the ionic liquid was increased to its maximal value, which essentially doubled the energy density of the battery, resulting in a cell-level energy density of ≤62 Wh kg–1. The resulting batteries were also characterized by high power densities of at least 489 W kg–1.
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