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.     

Spinel lithium titanate (Li4Ti5O12) as novel anode material for room-temperature sodium-ion battery

This is the first time that a novel anode material, spinel Li₄Ti₅O₁₂ which is well known as a “zero-strain” anode material for lithium storage, has been introduced for sodium-ion battery. The Li₄Ti₅O₁₂ shows an average Na storage voltage of about 1.0 V and a reversible capacity of about 145 mAh/g, thereby making it a promising anode for sodium-ion battery. E_x-situ X-ray diffraction (XRD) is used to investigate the structure change in the Na insertion/deinsertion process. Based on this, a possible Na storage mechanism is proposed.     

钠离子电池新型Cu基隧道型氧化物正极材料研究

成本较为低廉的钠离子电池成为储能领域的新秀,备受关注.以Na₂CO₃,CuO,Fe₂O₃,MnO₂和TiO₂为原料,通过简单的固相反应法合成了一系列新型Cu基隧道结构化合物.通过X射线衍射（XRD）、扫描电子显微镜（SEM）和电化学性能测试对所得样品的结构、形貌以及电化学性能进行了表征.XRD结果表明材料结构与Na_0.44MnO₂一样为隧道结构,空间群为pbam.室温下的电化学性能测试表明Mn替代的样品在1.5~4.1 V的范围内表现出了90 mAh/g的比容量,循环稳定,倍率性能较好,1C容量保持率仍为74%.XPS结果验证了Cu在充放电过程中参与了变价.原位XRD结果表明Na_0.66Cu_0.17Mn_0.33Ti_0.5O₂电极材料在1.5~4.1 V的范围内可以保持稳定的隧道型结构.本工作首次报道了Cu在隧道型结构材料中的变价行为,为进一步设计隧道结构的材料以及钠离子电池正极材料提供新思路.     

A high-performance rechargeable Li–O_2 battery with quasi-solid-state electrolyte

A novel transparent and soft quasi-solid-state electrolyte(QSSE) was proposed and fabricated, which consists of ionic liquid(PYR_(14)TFSI) and nano-fumed silica. The QSSE demonstrates high ionic conductivity of 4.6×10~(-4) S/cm at room temperature and wide electrochemical stability window of over 5 V. The Li–O_2 battery using such quasi-solidstate electrolyte exhibits a low charge-discharge overpotential at the first cycle and excellent long-term cyclability over 500 cycles.     

Novel copper redox-based cathode materials for room-temperature sodium-ion batteries

Layered oxides of P2-type Nao.68Cuo.34Mno.6602, P2-type Nao.68Cuo.34Mno.50Tio.1602, and O＇3-type NaCuo.67Sbo.3302 were synthesized and evaluated as cathode materials for room-temperature sodium-ion batteries. The first two materials can deliver a capacity of around 70 mAh/g. The Cu2＋ is oxidized to Cu3＋ during charging, and the Cu3＋ goes back to Cu2＋ upon discharging. This is the first demonstration of the highly reversible change of the redox couple of Cu2＋/Cu3＋ with high storage potential in secondary batteries.     

Highly Emcient Dye-Sensitized Solar Cells Using a Composite ElectrolyteConsisting of LiI（CH3OH）4-I2, SiO2 Nano-Particles and an Ionic Liquid

Solid-state electrolyte LiI(CH3OH)4-I2 is used in dye-sensitized solar cells (DSSCs). The DSSCs using only the LiI(CH3OH)4-I2 electrolyte show very poor performance due to the quick crystal growth of LiI(CH3OH)4. In order to improve the performance of DSSCs, we prepare a composite electrolyte by adding Si02 nano-particles and an ionic liquid, 1-methyl-3-ethylimidazolium iodide, into the original solid-state electrolyte. High efficiency of 4.3% is achieved by applying this composite electrolyte to DSSCs.     

锂离子电池用具有分级三维离子电子混合导电网络结构的纳微复合电极材料

文章评述了分级三维离子电子混合导电网络结构和具有该结构的纳微复合电极材料在锂离子电池中的应用等方面的最新研究工作进展.首先介绍了纳微复合电极结构相关概念及其优缺点,然后列举了一些运用此概念设计并构筑出的电极材料实例.研究证明,此新型电极结构能够大幅提高锂离子电池电极材料的储锂性能,并且该结构设计还可推广到其他电化学储能...     

FT-Raman spectroscopy study of solvent-in-salt electrolytes

Cation–anion interaction with different ratios of salt to solvent is investigated by FT-Raman spectroscopy. The fitting result of the C–N–C bending vibration manifests that the cation–anion coordination structure changes tremendously with the variation of salt concentration. It is well known that lithium-ion transport in ultrahigh salt concentration electrolyte is dramatically different from that in dilute electrolyte, due to high viscosity and strong cation–anion interaction. In ultrahigh salt concentrated "solvent-in-salt" electrolyte(SIS-7#), we found, on one hand, that the cation and anion in the solution mainly formed cation–anion pairs with a high Li~+coordination number(≥ 1), including intimate ion pairs(20.1%) and aggregated ion pairs(79.9%), which not only cause low total ionic conductivity but also cause a high lithium transference number(0.73). A possible lithium transport mechanism is proposed: in solvent-in-salt electrolytes, lithium ions' direct movement presumably depends on Li-ion exchange between aggregated ion pairs and solvent molecules, which repeats a dissolving and re-complexing process between different oxygen groups of solvent molecules.     

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.