This Review covers a sequence of key discoveries and technical achievements that eventually led to the birth of the lithium-ion battery. In doing so, it not only sheds light on the history with the advantage of contemporary hindsight but also provides insight and inspiration to aid in the ongoing quest for better batteries of the future. A detailed retrospective on ingenious designs, accidental discoveries, intentional breakthroughs, and deceiving misconceptions is given: from the discovery of the element lithium to its electrochemical synthesis; from intercalation host material development to the concept of dual-intercalation electrodes; and from the misunderstanding of intercalation behavior into graphite to the comprehension of interphases. The onerous demands of bringing all critical components (anode, cathode, electrolyte, solid-electrolyte interphases), each of which possess unique chemistries, into a sophisticated electrochemical device reveal that the challenge of interfacing these originally inco...

Before Li Ion Batteries

Safety concerns about organic media-based batteries are the key public arguments against their widespread usage. Aqueous batteries (ABs), based on water which is environmentally benign, provide a promising alternative for safe, cost-effective, and scalable energy storage, with high power density and tolerance against mishandling. Research interests and achievements in ABs have surged globally in the past 5 years. However, their large-scale application is plagued by the limited output voltage and inadequate energy density. We present the challenges in AB fundamental research, focusing on the design of advanced materials and practical applications of whole devices. Potential interactions of the challenges in different AB systems are established. A critical appraisal of recent advances in ABs is presented for addressing the key issues, with special emphasis on the connection between advanced materials and emerging electrochemistry. Last, we provide a roadmap starting with material design and ending with the commercialization of next-generation reliable ABs.

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Roadmap for advanced aqueous batteries: From design of materials to applications.

With a worldwide trend towards the efficient use of renewable energies and the rapid expansion of the electric vehicle market, the importance of rechargeable battery technologies, particularly lithium-ion batteries, has steadily increased. In the past few years, a major breakthrough in electrolyte materials was achieved by simply increasing the salt concentration in suitable salt–solvent combinations, offering technical superiority in numerous figures of merit over alternative materials. This long-awaited, extremely simple yet effective strategy can overcome most of the remaining hurdles limiting the present lithium-ion batteries without sacrificing manufacturing efficiency, and hence its impact is now widely felt in the scientific community, with serious potential for industrial development. This Review aims to provide timely and objective information that will be valuable for designing better realistic batteries, including a multi-angle analysis of their advantages and disadvantages together with future perspectives. Emphasis is placed on the pathways to address the remaining technical and scientific issues rather than re-highlighting the many technical advantages. New electrolyte materials can offer breakthroughs in the development of next-generation batteries. Here Atsuo Yamada and colleagues review the progress made and the road ahead for salt-concentrated electrolytes, an emerging and promising electrolyte candidate.

Advances and issues in developing salt-concentrated battery electrolytes

Recent Progress of the Solid-State Electrolytes for High-Energy Metal-Based Batteries

Correction for ‘Review of electrical energy storage technologies, materials and systems: challenges and prospects for large-scale grid storage’ by Turgut M. Gur, Energy Environ. Sci., 2018, DOI: 10.1039/c8ee01419a.

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Correction: Review of electrical energy storage technologies, materials and systems: challenges and prospects for large-scale grid storage

The use of 'water-in-salt' electrolytes has considerably expanded the electrochemical window of aqueous lithium-ion batteries to 3 to 4 volts, making it possible to couple high-voltage cathodes with low-potential graphite anodes1-4. However, the limited lithium intercalation capacities (less than 200 milliampere-hours per gram) of typical transition-metal-oxide cathodes5,6 preclude higher energy densities. Partial7,8 or exclusive9 anionic redox reactions may achieve higher capacity, but at the expense of reversibility. Here we report a halogen conversion-intercalation chemistry in graphite that produces composite electrodes with a capacity of 243 milliampere-hours per gram (for the total weight of the electrode) at an average potential of 4.2 volts versus Li/Li+. Experimental characterization and modelling attribute this high specific capacity to a densely packed stage-I graphite intercalation compound, C3.5[Br0.5Cl0.5], which can form reversibly in water-in-bisalt electrolyte. By coupling this cathode with a passivated graphite anode, we create a 4-volt-class aqueous Li-ion full cell with an energy density of 460 watt-hours per kilogram of total composite electrode and about 100 per cent Coulombic efficiency. This anion conversion-intercalation mechanism combines the high energy densities of the conversion reactions, the excellent reversibility of the intercalation mechanism and the improved safety of aqueous batteries.

Aqueous Li-ion battery enabled by halogen conversion–intercalation chemistry in graphite

4.0 V Aqueous Li-Ion Batteries

DOI: 10.1002/aenm.201802986 exceptional battery performance is still a significant challenge at high temperatures due to the structural degradation caused by the fast transfer of alkali-ions.[4] Therefore, Li-ion batteries have been intensively investigated as high temperature batteries owing to the smallest ion size of Li among the alkali-ions.[4,5] Nevertheless, the scarcity and unevenly global distribution of Li resource is an obstacle for the further development of Li-ion batteries.[3,6] One promising strategy to replace Li-ion batteries is developing hightemperature K-ion batteries (KIBs), which have distinguished advantages among alkali-ion batteries, e.g., the significantly more abundance of K than Li (2.09 vs 0.0017 wt% in the Earth crust) and lower redox potential of K+/K than Na+/Na (−2.93 vs −2.71 V).[3,6,7] All these merits ensure KIBs provide clean energy with low cost and high energy density. However, the larger ion size of K+ than Li+ and Na+ results in a significant structural deterioration for the conversion and intercalation electrodes. The conversion electrodes suffer from a large volume change that is tremendously significant in KIBs,[4,8,9] while the capacity of the intercalation electrodes is very low.[10,11] As reported by Amine’s group, stabilizing the material surface is the key factor for cycling Li-ion batteries at high temperatures such as 55 °C.[12] Thus, it is extremely challenging for KIB electrodes to withstand a temperature above 55 °C, due to the less stable solid electrolyte interphase (SEI) compared to the Li counterpart.[13] Herein, we designed an organic anode that stores K-ions through surface reaction for high-temperature KIBs beyond the current operating temperature of 55 °C with high rate capability and long cycle life. Azobenzene-4,4′-dicarboxylic acid potassium salts (ADAPTS) with a redox center of azo group (NN) is selected to reversibly react with K+, as shown in Figure 1a. Different from the conversion and intercalation reactions, ADAPTS with surface reaction can largely retain the structural stability during the reversible electrochemical reactions between azo group and K+ even at a high temperature. Furthermore, organic compounds are ideal electrode materials for clean energy applications since they are inexpensive and sustainable.[14,15] At the ambient temperature, the ADAPTS anode delivers a reversible capacity of 109 mAh g−1 at 0.1C for 100 cycles and a long-term cycle life of 1000 cycles is achieved The wide applications of rechargeable batteries require state-of-the-art batteries that are sustainable (abundant resource), tolerant to hightemperature operations, and excellent in delivering high capacity and longterm cycling life. Due to the scarcity and uneven distribution of lithium, it is urgent to develop alternative rechargeable batteries. Herein, an organic compound, azobenzene-4,4′-dicarboxylic acid potassium salts (ADAPTS) is developed, with an azo group as the redox center for high performance potassium-ion batteries (KIBs). The extended π-conjugated structure in ADAPTS and surface reactions between ADAPTS and K-ions enable the stable charge/discharge of K-ion batteries even at high temperatures up to 60 °C. When operated at 50 °C, ADAPTS anode delivers a reversible capacity of 109 mAh g−1 at 1C for 400 cycles. A reversible capacity of 77 mAh g−1 is retained at 2C for 1000 cycles. At 60 °C, the ADAPTS-based KIBs deliver a high capacity of 113 mAh g−1 with 81% capacity retention at 2C after 80 cycles. The exceptional electrochemical performance demonstrates that ADAPTS is a promising electrode material for high-temperature KIBs.

An Organic Anode for High Temperature Potassium-Ion Batteries

In Fig. 3e of this Letter, the labels "Br-Cl1" and "Br-Cl2" should read "Br-Br1" and "Br-Br2", respectively. In the Methods section 'Preparation of electrodes', the phrase "anhydrous LiBr/LiCl was replaced by LiBr·H2O (99.95%; Sigma-Aldrich) and LiCl (99.95%; Sigma-Aldrich)" should read "anhydrous LiBr/LiCl was replaced by LiBr·H2O (99.95%; Sigma-Aldrich) and LiCl·H2O (99.95%; Sigma-Aldrich)". These errors have been corrected online.

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Tingting Qing

Papers

Aqueous Li-ion battery enabled by halogen conversion–intercalation chemistry in graphite

4.0 V Aqueous Li-Ion Batteries

An Organic Anode for High Temperature Potassium-Ion Batteries

Author Correction: Aqueous Li-ion battery enabled by halogen conversion–intercalation chemistry in graphite