A comprehensive review of pre-lithiation/sodiation additives for Li-ion and Na-ion batteries

Lithium/Sodium-ion batteries(LIB/SIB)have attracted enormous attention as a promising electrochemical energy storage system due to their high energy density and long cycle life.One of the major hurdles is the initial irreversible capacity loss during the first few cycles owing to forming the solid electrolyte interphase layer(SEI).This process consumes a profusion of lithium/sodium,which reduces the overall energy density and cycle life.Thus,a suitable approach to compensate for the irreversible capacity loss must be developed to improve the energy density and cycle life.Pre-lithiation/sodiation is a widely accepted process to compensate for the irreversible capacity loss during the initial cycles.Various strategies such as physical,chemical,and electrochemical pre-lithiation/sodiation have been explored;however,these approaches add an extra step to the current manufacturing process.Alternative to these strategies,pre-lithiation/sodiation additives have attracted enormous attention due to their easy adaptability and compatibility with the current battery manufacturing process.In this review,we consolidate recent developments and emphasize the importance of using pre-lithiation/sodiation additives(anode and cathode)to overcome the irreversible capacity loss during the initial cycles in lithium/sodium-ion batteries.This review also addresses the technical and scientific challenges of using pre-lithiation/sodiation additives and offers the insights to boost the energy density and cycle life with their possible commercial exploration.The most important prerequisites for designing effective pre-lithiation/sodiation additives have been explored and the future directions have been discussed.

New insights into the pre-lithiation kinetics of single-crystalline Ni-rich cathodes for long-life Li-ion batteries

Developing single-crystalline Ni-rich cathodes is an effective strategy to improve the safety and cycle life of Li-ion batteries(LIBs).However,the easy-to-loss of Li and O in high-temperature lithiation results in unsatisfactory ordered layered structure and stoichiometry.Herein,we demonstrate the synthesis of highly-ordered and fully-stoichiometric single-crystalline LiNi_(0.83)Co_(0.12)Mn_(0.05)O_(2)(SC-NCM83)cathodes by the regulation of pre-lithiation kinetics.The well-balanced pre-lithiation kinetics have been proved to greatly improve the proportion of layered phase in the intermediate by inhibiting the formation of metastable spinel phase,which promoted the rapid transformation of the intermediate into highly-ordered layered SC-NCM83 in the subsequent lithiation process.After coating a layer of Li_(2)O–B_(2)O_(3),the resultant cathodes deliver superior cycling stability with 90.9%capacity retention at 1C after 300 cycles in pouch-type full batteries.The enhancement mechanism has also been clarified.These findings exhibit fundamental insights into the pre-lithiation kinetics process for guiding the synthesis of high-quality singlecrystalline Ni-rich cathodes.

In situ tracking of the lithiation and sodiation process of disodium terephthalate as anodes for rechargeable batteries by Raman spectroscopy

Organic compounds represent an appealing group of electrode materials for rechargeable batteries due to their merits of biomass,sustainability,environmental friendliness,and processability.Disodium terephthalate(Na_(2)C_(8)H_(4)O_(4),Na_(2)TP),an organic salt with a theoretical capacity of 255 mAh·g^(-1),is electroactive towards both lithium and sodium.However,its electrochemical energy storage(EES)process has not been directly observed via in situ characterization techniques and the underlying mechanisms are still under debate.Herein,in situ Raman spectroscopy was employed to track the de/lithiation and de/sodiation processes of Na2TP.The appearance and then disappearance of the–COOLi Raman band at 1625 cm^(-1) during the de/lithiation,and the increase and then decrease of the–COONa Raman band at 1615 cm^(-1) during the de/sodiation processes of Na2TP elucidate the one-step with the 2Li+or 2Na+transfer mechanism.We also found that the inferior cycling stability of Na2TP as an anode for sodium-ion batteries(SIBs)than lithium-ion batteries(LIBs)could be due to the larger ion radium of Na+than Li+,which results in larger steric resistance and polarization during EES.The Na2TP,therefore,shows greater changes in spectra during de/sodiation than de/lithiation.We expect that our findings could provide a reference for the rational design of organic compounds for EES.

钠离子电池预钠化技术研究进展

介绍了钠离子电池预钠化技术的研究进展。叙述了首圈循环效率低的原因,并综述了最新正负极预钠化技术的发展情况,总结了不同类别预钠化技术的优势和不足,对预钠化技术的发展趋势进行了评述。

钠离子化和质子化环肽类似物的碰撞裂解途径比较

近年来,环肽因其生物学功能和结构多样性受到广泛关注,但它们的结构鉴定比线性肽更困难。碰撞活化解离(CAD)质谱技术是分析环肽结构的重要手段。本工作通过电喷雾电离技术产生4种环肽类似物的钠离子化和质子化离子,并采用串联质谱进行研究。钠离子化和质子化离子的CAD谱图表现出较大差异,其中钠离子化复合物在测序方面优于质子化复合物。对于钠离子化复合物来说,钠离子与环内的主链羰基氧原子配位,其CAD谱图易于解析;而质子化复合物的CAD谱图存在多个平行的解离通道,比较复杂,并且这种复杂性与环肽类似物的官能团密切相关。结合2种复合物的CAD谱图,可以提供环肽类似物的互补信息,使其结构鉴定更加可靠。

Lithiation-induced controllable vacancy engineering for developing highly active Ni_(3)Se_(2) as a high-rate and large-capacity battery-type cathode in hybrid supercapacitors

The poor rate capability and low capacity are huge barriers to realize the commercial applications of battery-type transition metal compounds(TMCs) cathode.Herein,numerous Se vacancy defects are introduced into the Ni_(3)Se_(2)lamellas by pre-lithiation technique,which can be acted as a novel class of battery-type cathode for hybrid supercapacitors.Appropriately modulating the contents of the preembedded lithium(Li) ions can induce a controllable vacancy content in the series of as-prepared products,effectively endowing a fast reaction kinetic and high activity for the cathode.Benefiting from the distinct design,the optimized cathode(Li2-Ni_(3)Se_(2)) presents a high specific capacity of 236 mA h g^(-1)at1 A g^(-1),importantly,it can still possess 117 mA h g^(-1)when the current density is increased up to 100A g^(-1),exhibiting relatively high rate capability.It is much superior to other battery-type TMC cathodes reported in previous studies.Moreover,the cathode also shows the excellent cycling stability with 92%capacity retention after 3,000 cycles.In addition,a hybrid supercapacitor(HSC) is assembled with the obtained Li2-Ni_(3)Se_(2)as the cathode and active carbon(AC) as the anode,which delivers a high energy density of 77 W h kg^(-1)at 4 kW kg^(-1)and long-term durability(90% capacitance retention after 10,000 cycles).Therefore,the strategy not only provides an effective way to realize the controllable vacancy content in TMCs for achieving high-perfo rmance cathodes for HSC,but also further promotes their large-scale applications in the energy storage fields.

Boosting the capability of Li_(2)C_(2)O_(4)as cathode pre-lithiation additive for lithium-ion batteries

Li_(2)C_(2)O_(4),with a high theoretical capacity of 525 mAh·g^(−1)and good air stability,is regarded as a more attractive cathode prelithiation additive in contrast to the reported typical inorganic pre-lithiation compounds which are quite air sensitive.However,its obtained capacity is much lower than the theoretical value and its delithiation potential(>4.7 V)is too high to match with the most commercial cathode materials,which greatly impedes its practical application.Herein,we greatly improve the pre-lithiation performance of Li_(2)C_(2)O_(4)as cathode additive with fulfilled capacity at a much-reduced delithiation voltage,enabling its wide applicability for typical commercial cathodes.We increase the capacity of Li_(2)C_(2)O_(4)from 436 to 525 mAh·g^(−1)by reducing its particle size.Through optimizing the types of conductive additives,introducing nano-morphological NiO,MnO2,etc.as catalysts,and innovatively designing a bilayer electrode,the delithiation potential of Li_(2)C_(2)O_(4)is successfully reduced from 4.778 to 4.288 V.We systematically study different particle size,conductive additives,and catalysts on the delithiation behavior of Li_(2)C_(2)O_(4).Finally,it is applied to pre-lithiate the hard carbon anode,and it is found that Li_(2)C_(2)O_(4)could effectively increase the capacity of the full cell from 79.0 to 140.0 mAh·g^(−1)in the first cycle.In conclusion,our study proves that improving the reactivity is an effective strategy to boost the pre-lithiation of Li_(2)C_(2)O_(4).

酸活化法制备钠基膨润土工艺研究

研究了由钙基膨润土通过酸活化制备钠基膨润土的工艺条件 ;对产品的物理性能进行了检测。结果表明 :经过精化、酸化和钠化处理制得的钠基膨润土 。

钠离子电池预钠化技术研究进展

钠离子电池是下一代低成本和高性能规模储能电池技术之一,预钠化技术可有效补充其在循环过程中的不可逆钠损耗,因此在钠离子电池的实际应用中具有重要地位。本工作综述了目前已有的预钠化方法,包括物理预钠化、电化学预钠化、化学反应预钠化、正极添加剂以及富钠正极。考虑各种预钠化技术安全性、可操作性、高效性和整体成本等诸多因素,分析了各种预钠化技术的优势与不足,指出了目前预钠化技术存在的问题,最后展望了预钠化技术在未来钠离子电池中的商业前景和发展方向。物理预钠化操作简单方便,但安全性是其主要问题;电化学预钠化能获得稳定的SEI膜,但受限于繁琐的工艺步骤;化学反应预钠化也能形成均匀致密的SEI膜,但对气氛有一定的要求,且溶剂昂贵;正极添加剂操作简单方便,但对其产生的残留物和气体的研究甚少;富钠正极稳定性好,但受限于种类太少。未来的预钠化研究需要综合考虑成本、环保、安全和稳定性等因素,并对副反应和副产物的影响机理进行深入地研究。

原位透射电镜研究正交相五氧化二铌纳米片的电化学储钠机制

由于正交相五氧化二铌(T-Nb_(2)O_(5))为ReO_(3)型层状结构,锂、钠离子可以在其(001)平面快速脱嵌,而在[001]方向的传输一般较难。本研究通过原位透射电子显微镜(Transmission Electron Microscope,TEM)方法研究钠在T-Nb_(2)O_(5)纳米片(001)面内及[001]方向的钠离子电化学嵌入行为,发现由于纳米片晶体存在大量的位错和畴界,钠离子可通过这些缺陷穿越(001)面扩散,并进而在深层的(001)面内快速扩散。同时,本研究还发现刚合成的T-Nb_(2)O_(5)纳米片在[001]方向上存在调制结构,存在交替分布的压应变和张应变区域,而钠离子的嵌入可以调节这些应变分布。

First-principles insight into Li and Na ion storage in graphene oxide

The structural, electronic, and adsorption properties of Li/Na ions on graphene decorated by epoxy groups are investigated by first-principles calculations based on density functional theory.Our results show that the concentration of epoxy groups remarkably affects the structural and electronic properties of graphene.The bandgaps change monotonically from0.16 eV to 3.35 eV when the O coverage increases from 12.5% to 50%(O/C ratio).Furthermore, the highest lithiation potential of 2.714 V is obtained for the case of graphene oxide(GO) with 37.5 % O coverage, while the highest sodiation potential is 1.503 V for GO with 12.5% O coverage.This clearly demonstrates that the concentration of epoxy groups has different effects on Li and Na storage in GO.Our results provide a new insight into enhancing the Li and Na storage by tuning the concentration of epoxy groups on GO.

Pomegranate-inspired porous SnSe/ZnSe@C anode:A stress-buffer nanostructure for fast and ultrastable sodium-ion storage

Tin selenide(SnSe)is considered as a potential anode for sodium-ion batteries(SIBs)owing to its high theoretical specific capacity.Unfortunately,it suffers from drastic volume expansion/contraction during sodium ions insertion/extraction,resulting in poor cycling stability.Herein,a pomegranate-inspired porous carbon shell wrapped heterogeneous SnSe/ZnSe composite(SnSe/ZnSe@C)is exquisitely designed and fabricated through electrostatic spraying followed by high-temperature selenization.The polyacrylonitrile-derived carbon shell acts as an adhesive to link the porous cubic SnSe/ZnSe and form highly interconnected microcircuits to improve the electron/ion transfer efficiency and inhibit the bulk volume change of internal metallic selenide nanoparticles and polyselenides dissolution during repeated cycling.Moreover,the abundant heterostructure interface of SnSe/ZnSe further significantly accelerates the electrons/ions transport.As a result,the as-prepared SnSe/ZnSe@C electrode exhibits a high specific capacity(508.3 m Ah g^(-1)at 0.05 A g^(-1)),excellent rate performance(177.8 m Ah g^(-1)at 10.0 A g^(-1)),and remarkable cycling stability(195.9 m Ah g^(-1)after 10,000 cycles at 5.0 A g^(-1)).Furthermore,in-situ Xray diffraction(XRD)/Raman,ex-situ transmission electron microscopy,and kinetic analysis clearly reveal a four-step electrochemical reaction process and battery-capacitor dual-mode sodium storage mechanism.This work provides a new perspective for developing commercial SIBs anode materials with high capacity and long lifespan.

Design and performance improvement of SiNPs@graphene@C composite with a popcorn structure

Silicon anodes are considered to be the most promising alternatives owing to their theoretical specific capacity,which is almost 10 times higher than that of graphite anodes.However,huge volume changes during charging and discharging affect their interface stability,which strongly limits their application in commercial batteries.Herein,a popcorn-structured silicon-carbon composite(SiNPs@graphene@C),composed of silicon nanoparticles(SiNPs),graphene spheres and pitch-based carbon,is prepared by spraydrying followed by a wet process.The resulting SiNPs@graphene@C composite has good flexibility and elastic-strain capacity due to the graphene substrate,and it possesses macrostructural integrity and mechanical stability during cycling due to the rigid carbon–carbon chemical bonds.As a result,it shows a discharge-specific capacity of 481.3 mAh g^(-1)and a capacity retention of 82.9%after 500 cycles at 1 A g^(-1).Besides,the initial coulomb efficiency is increased from 65.7%to 86.5%by pre-lithiation,which improves the feasibility of commercialising the SiNPs@graphene@C composite.

钠离子电容器负极的双功能补钠研究

电极的首次库伦效率低是限制快充钠离子电容器规模化使用的原因之一,这主要源于电解液的不可逆分解以及电极材料造成的不可逆损失.我们选取高倍率特性的Nb_(2)O_(5)负极材料作为研究对象,采用钠萘/2-甲基-四氢呋喃作为预钠化剂,发展了一种简单且可精确调控的双功能预钠化剂,实现了预活化,获得了高稳定循环的NaxNb_(2)O_(5)电极,从而补偿了钠在材料中的不可逆吸收.研究发现,预钠化过程同时抵消了电解液分解所产生的损失,有利于在电极/电解液界面形成坚固的富含无机物的固体电解质界面膜.通过补偿Nb_(2)O_(5)负极的体相与界面的钠损失,构建了稳定且具有高能量密度的钠离子电容器.本研究为调控储钠电极的首次库伦效率及其在下一代钠离子电容器中的应用提供了新方法.

N,N-二甲基甲酰胺对氮化锂的稳定性机理及其在锂离子超级电容器预锂化中的应用

氮化锂是一种极好的零残留正极预锂化添加剂,可用于弥补锂离子电容器及锂离子电池在首圈的锂损失.但是,在电极制造过程中,氮化锂与非质子极性溶剂的相容性差,与N-甲基-2-吡咯烷酮(NMP)等常用溶剂具有很高的反应性,限制了以氮化锂作为预锂添加剂的技术推广应用.本文通过商业上可用的匀浆涂布途径制备了含氮化锂的电极,使用N,N-二甲基甲酰胺(DMF)作为匀浆溶剂.实验分析和DFT模拟证实了DMF的分子稳定机理,DMF的脱氢能明显大于其他常用溶剂.添加20%氮化锂的软包装锂离子电容器具有出色的倍率性能、循环稳定性和超高的能量密度,其能量密度是不含Li3N器件的2.3倍,1万次充放电循环后,其能量保持率高达90%.

Mesoporous carbon material as cathode for high performance lithium-ion capacitor

Mesoporous carbon（MC） material with high specific surface area（1432 m^2/g）, large pore volume（2.894 cm^3/g） and appropriate mesopore structure（about 6.5 nm） has been prepared. We use the magnesium citrate as the precursor of the carbon material and the nano-sized magnesium oxide（MgO）particles as template provided by magnesium citrate. The structure characterization and the electrochemical performance of MC are investigated. Compared with commercial activated carbon（AC） cathode, the utilization of MC cathode can obviously improve the energy density of LIC device. When the MC cathode is coupled with pre-lithiated hard carbon（HC） anode, the LIC device shows the optimal electrochemical performance, high energy density up to 95.4 Wh/kg and power density as high as 7.4 kW/kg（based on active material mass of two electrodes）, excellent capacity retention of 97.3% after 2000 cycles. The present work indicates the combination of MC electrode with HC electrodes as promising candidates for the realization of LIC with high energy density, high power density and long cycle life.

A two-step strategy for constructing stable gel polymer electrolyte interfaces for long-life cycle lithium metal batteries

Due to the high reactivity between the lithium metal and traditional organic liquid electrolyte,the reaction of lithium metal electrode is usually uneven and there are also unexpected side reactions.Therefore,construction of a stable solid electrolyte interface(SEI)is highly essential to improve the performance of lithium metal anode.Herein,a sandwich-like gel polymer electrolyte(GPE)is accurately prepared by in-situ polymerization of Polyacrylonitrile(PAN)nanofiber membrane with trihydroxymethylpropyl trimethylacrylate(TMPTMA)and 1,6-hexanediol diacrylate(HDDA).The resulting GPE with a tightly cross-linked gel skeleton exhibits high ionic conductivity and electrochemical window of 5.6 V versus Li/Li^(+).In particular,the pretreatment of Li metal anode can improve the interfacial wettability,and the synergy of the chemically pretreated Li metal anode surface and the GPE can electrochemically in situ generate SEI with compositionally stable and fluorine-rich inorganic components.Owing to these unique advantages,the interfacial compatibility between the GPE and lithium metal is greatly improved.Meanwhile,the formed SEI can inhibit the formation of lithium dendrites,and decomposition of GPE would be alleviated.The assembled Li-FEC|GPE|LiFePO_(4) full cell shows a high initial discharge capacity of 157.1 mA h g^(-1),and maintains a capacity retention of 92.3%after 100 cycles at 0.2C.