Failure analysis with a focus on thermal aspect towards developing safer Na-ion batteries

Safety requirements stimulate Na-based batteries to evolve from high-temperature Na–S batteries to room-temperature Na-ion batteries(NIBs).Even so,NIBs may still cause thermal runaway due to the external unexpected accidents and internal high activity of electrodes or electrolytes,which has not been comprehensively summarized yet.In this review,we summarize the significant advances about the failure mechanisms and related strategies to build safer NIBs from the selection of electrodes,electrolytes and the construction of electrode/electrolyte interfaces.Considering the safety risk,the thermal behaviors are emphasized which will deepen the understanding of thermal stability of different NIBs and accelerate the exploitation of safe NIBs.     

Mg-doped layered oxide cathode for Na-ion batteries

Na-ion batteries (NIBs) are regarding as the optimum complement for Li-ion batteries along with the rapid development of stationary energy storage systems. In order to meet the commercial demands of cathodes for NIBs, O3-type Cu containing layered oxide Na_0.90Cu_0.22Fe_0.30Mn_0.48O₂ with good comprehensive performance and low-cost element components is very promising for the practical use. However, only part of the Cu³⁺/Cu²⁺ redox couple participated in the redox reaction, thus impairing the specific capacity of the cathode materials. Herein, Mg²⁺-doped O3-Na_0.90Mg_0.08Cu_0.22Fe_0.30Mn_0.40O₂ layered oxide without Mn³⁺ was synthesized successfully, which exhibited improved reversible specific capacity of 118 mAh/g in the voltage range of 2.4-4.0 V at 0.2 C, corresponding to the intercalation/deintercalation of 0.47 Na⁺ (0.1 more than that of Na_0.90Cu_0.22Fe_0.30Mn_0.48O₂). This work demonstrates an important strategy to obtain advanced layered oxide cathodes for NIBs.     

Gas treatment protection of metallic lithium anode

The effects of different coating layers on lithium metal anode formed by reacting with different controlled atmospheres(argon,CO_2–O_2(2:1),N_2,and CO_2–O_2–N_2(2:1:3))have been investigated.The obtained XRD,second ion mass spectroscopy(SIMS),and scanning probe microscope(SPM)results demonstrate the formation of coating layers composed of Li_2CO_3,Li_3N,and the mixture of them on lithium tablets,respectively.The Li/Li symmetrical cell and Li/S cell are assembled to prove the advantages of the protected lithium tablet on electrochemical performance.The comparison of SEM and SIMS characterizations before/after cycles clarifies that an SEI-like composition formed on the lithium tablets could modulate the interfacial stabilization between the lithium foil and the ether electrolyte.     

低温水系碱金属离子电池的研究进展

水系碱金属离子电池因具有高安全性、低成本和环境友好等优势而成为前沿研究的热点之一,在大规模储能领域具有良好的应用前景.然而,许多水系碱金属离子电池在低温条件下出现运行故障或展现出极低的放电比容量,严重限制了其在恶劣的严寒气候条件下的广泛应用.本综述首先梳理了近年来低温水系碱金属离子电池的研究进展.随后从电解液、电极和界面三个方面分别探讨了水系碱金属离子电池在低温下运行所面对的挑战和相应的失效机制,同时系统地介绍了提高电池低温性能的改性策略并加以评述,以期为水系碱金属离子电池低温性能的进一步提升及其实际应用提供参考并指明方向.     

钠离子层状氧化物材料相变及其对性能的影响

钠离子电池近年来在大规模储能领域展现出优异的发展和应用前景.由于钠离子层状过渡金属氧化物正极材料(Na_xTMO₂)具有比容量高、容易制备、电压可调和成本低的优势,在学术界和产业界得到了广泛的关注与研究.但较大的Na~+半径和较强的Na~+-Na~+静电排斥作用,导致Na_xTMO₂具有多种结构类型和复杂的结构转变,以及由此形成了多重结构-性能关系.本文详细介绍了Na_xTMO₂的结构类型,综述了在Na~+脱出/嵌入过程中引发的结构演变,旨在揭示钠离子层状过渡金属氧化物正极材料结构转变机理及其对电化学性能的影响,最后讨论了现存的挑战并提出了改进策略.     

A High-Temperature β-Phase NaMnO_2 Stabilized by Cu Doping and Its Na Storage Properties

The high-temperature β-phase NaMnO_2 is a promising material for Na-ion batteries(NIBs) due to its high capacity and abundant resources. However, the synthesis of phase-pure -NaMnO_2 is burdensome and costineffective because it needs to be sintered under oxygen atmosphere at high temperature and followed by a quenching procedure. Here we first report that the pure β phase can be stabilized by Cu-doping and easily synthesized by replacing a proportion of Mn with Cu via a simplified process including sintering in air and cooling to room temperature naturally. Based on the first-principle calculations, the band gap decreases from 0.7 eV to 0.3 eV, which indicates that the electronic conductivity can be improved by Cu-doping. The designed -NaCu_(0.1)Mn_(0.9)O_2 is applied as cathode in NIBs, exhibiting an energy density of 419 Wh/kg and better performance in terms of rate capability and cycling stability than those in the undoped case.     

Anionic redox reaction mechanism in Na-ion batteries

Na-ion batteries (NIBs), as one of the next-generation rechargeable battery systems, hold great potential in large-scale energy storage applications owing to the abundance and costeffectiveness of sodium resources. Despite the extensive exploration of electrode materials, the relatively low attainable capacity of NIBs hinders their practical application. In recent years, the anionic redox reaction (ARR) in NIBs has been emerging as a new paradigm to deliver extra capacity and thus offers an opportunity to break through the intrinsic energy density limit. In this review, the fundamental investigation of the ARR mechanism and the latest exploration of cathode materials are summarized, in order to highlight the significance of reversible anionic redox and suggest prospective developing directions.     

室温钠离子电池材料及器件研究进展

在众多电化学储能技术中,室温钠离子电池除具有能量密度高、循环寿命长的特点外,还具有其他电池体系所不具有的资源丰富和成本低廉的优势,是一种较理想的规模储能电池体系.中国科学院物理研究所自2011年以来致力于低成本、安全环保的钠离子电池技术的研发,在正、负极材料和电解质材料开发中取得了多项原创性的研究成果,并研制出Ah级钠离子软包电池.例如,首次发现Cu~(2+)/Cu~(3+)氧化还原电对高度可逆并设计了Na-Cu-Fe-Mn-O基低成本层状氧化物正极材料;首次通过简单的一步碳化法制备出性价比高的无烟煤基负极材料;首次将一种新型的钠盐NaFSI应用于碳酸酯非水电解质以大幅度提升电极材料的性能等.本文综述了物理所在钠离子电池材料及器件研究中所取得的重要进展和突破,期待经过进一步不懈地努力为实现钠离子电池的产业化做出重要贡献.     

Low-Temperature Aqueous Na-Ion Batteries: Strategies and Challenges of Electrolyte Design

Aqueous Na-ion batteries(ANIBs) are considered to be promising secondary battery systems for grid-scale energy storage applications and have attracted widespread attention due to their unique merits of rich resources of Na, as well as the inherent safety and low cost of aqueous electrolytes. However, the narrow electrochemical stability widow and high freezing point of traditional dilute aqueous electrolytes restrict their multi-scenario applications. Considering the charge-storage mechanism of ...