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Alloy Anodes for Rechargeable Alkali-Metal Batteries: Progress and Challenge He Liu,† Xin-Bing Cheng,† Jia-Qi Huang,‡ Stefan Kaskel,§,⊥ Shulei Chou,∥ Ho Seok Park,# and Qiang Zhang*,†
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Beijing Key Laboratory of Green Chemical Reaction Engineering and Technology, Department of Chemical Engineering, Tsinghua University, Beijing 100084, P.R. China ‡ Advanced Research Institute for Multidisciplinary Science, Beijing Institute of Technology, Beijing 100081, China § Department of Inorganic Chemistry, Dresden University of Technology, Bergstrasse 66, 01069 Dresden, Germany ⊥ Fraunhofer Institute for Material and Beam Technology Winterbergstraße 28, 01277 Dresden, Germany ∥ Institute for Superconducting and Electronic Materials, University of Wollongong, Wollongong, New South Wales 2522, Australia # School of Chemical Engineering, Sungkyunkwan University, 2066, Seoburo, Jangan-gu, Suwon 440-746, Korea ABSTRACT: Alkali metal electrodes (including lithium (Li), sodium (Na), and potassium (K)) have been strongly considered as promising candidates for next-generation batteries, beyond lithium ion batteries, because of their high theoretical specific capacities and very low electrochemical potentials. However, all alkali metal anodes are susceptible to dendrite growth, causing safety concerns, low energy efficiency, and short lifespan, which severely hampers their practical applications in working rechargeable batteries. Recently, alloy anodes with two metal components are effective to protect alkali metal anodes. In this Perspective, we analyze the alkali-metal alloy anodes based on their contribution to dendrite suppression, released capacity, and safety enhancement. Recent progress in alloy anodes, including Li/Na−X alloy (X represents the element of non-alkali metal), Li−Na alloy, and Na−K alloy, is reviewed. The perspectives and clear suggestions on the future of alkali-metal alloy anodes are presented. This sheds fresh light on the rational electrode architecture and materials for alkali metal anode and opens a new chapter for next-generation battery systems.
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capacity rechargeable batteries are competitive with their Li rivals because of their earth abundant and low-cost nature.6−8 Considering the rise in energy density and reduction in cost of electrode materials, high-capacity alkali metal electrodes, including Li, Na, and K, are very likely to be employed in next-generation rechargeable batteries,9−13 in particular for all solid-state batteries.14−18 Actually, alkali-metal electrodes, especially Li metal anodes, have been employed as anode materials since the 1970s. Unfortunately, their low efficiency and poor lifespan and the battery fires, resulting from dendritic deposition, drove the Li metal anode out of practical application in rechargeable batteries.19−21 Similarly, both Na and K metal anodes also show dendrite growth.22−24 Further challenges arise from massive volume changes and the continuous consumption of electrolyte during repeated reformation of the solid electrolyte interphase (SEI). Methods for the suppression of dendrite growth have been extensively explored and can be divided into
ur life in the 21st century has been reshaped by lithium (Li)-ion battery (LIB) technologies since their first commercialization in the early 1990s. With
Considering the rise in energy density and reduction in cost of electrode materials, high-capacity alkali metal electrodes, including Li, Na, and K, are very hopeful to be employed in the next-generation rechargeable batteries, in particular for all solid state batteries continuous demands for high-energy-density and low-cost battery systems, novel anode materials and emerging electrochemistry beyond graphite anode in LIBs are being extensively investigated.1,2 On one hand, the metallic Li anode, the “Holy Grail” electrode, is adopted to release higher capacity and low electrochemical potential, which consequently can further enhance the energy density of working batteries.3−5 On the other hand, sodium (Na) and potassium (K)-based high© XXXX American Chemical Society
Received: April 18, 2019 Accepted: June 18, 2019 Published: June 18, 2019 217
DOI: 10.1021/acsmaterialslett.9b00118 ACS Materials Lett. 2019, 1, 217−229
Perspective
Cite This: ACS Materials Lett. 2019, 1, 217−229
ACS Materials Letters
Perspective
improving the capacity of negative anodes and their alloying− dealloying mechanism.81−86 These alloy anodes will not be included in this Perspective. Instead, the focus of this Perspective is on the binary alkali metal-containing alloy anodes composed of two kind of metals and their contribution toward protecting alkali metal from dendrite formation. It begins with the Li/Na−X alloy (X is the non-alkali metal), continues with the Li−Na alloy anode, and finishes with the Na−K alloy anode. The detailed perspectives and clear suggestions are also presented for the future development of alloy anodes. We strongly believe that rational design of alloy anode can make great breakthroughs in the suppression of dendrite growth though open questions remain for alloy anodes. There is still a long road toward the cells with high capacity, reversibility, longevity, and low-cost for actual demands and practical applications.
four categories: (1) modifications to SEI in nonaqueous electrolytes, including solvent and salt optimization,25 electrolyte additives,26−28 highly-concentrated electrolyte,29,30 ex-situ SEI/artificial interlayers,31−37 etc.; (2) employment of solidstate electrolytes (SSEs) with a high ionic conductivity and ion transference number, a high interfacial stability against alkali metallic anode, and a very low interfacial resistance;38−46 (3) structured electrode design, such as nano-/microstructured current collectors47−49 and 3D hosts (carbon,50−57 metal foam, etc.58−60); and (4) membrane separator design.61−65 These strategies effectively strengthen our understanding on the behavior of dendrite growth and render a safe and high-energydensity alkali metal-based battery in specific cycling conditions and cell patterns (usually coin cells with low capacities and low currents).66−68 However, large-energy pouch cells with alkali metal anodes operated at high currents exhibit a poor lifespan, usually
