Enhanced structural stability and durability in lithium-rich manganese-based oxide via surface double-coupling engineering

Lithium-rich manganese-based oxides(LRMOs) exhibit high theoretical energy densities, making them a prominent class of cathode materials for lithium-ion batteries. However, the performance of these layered cathodes often declines because of capacity fading during cycling. This decline is primarily attributed to anisotropic lattice strain and oxygen release from cathode surfaces. Given notable structural transformations, complex redox reactions, and detrimental interface side reactions in LRMOs, the development of a single modification approach that addresses bulk and surface issues is challenging. Therefore,this study introduces a surface double-coupling engineering strategy that mitigates bulk strain and reduces surface side reactions. The internal spinel-like phase coating layer, featuring threedimensional(3D) lithium-ion diffusion channels, effectively blocks oxygen release from the cathode surface and mitigates lattice strain. In addition, the external Li_(3)PO_(4) coating layer, noted for its superior corrosion resistance, enhances the interfacial lithium transport and inhibits the dissolution of surface transition metals. Notably, the spinel phase, as excellent interlayer, securely anchors Li_(3)PO_(4) to the bulk lattice and suppresses oxygen release from lattices. Consequently, these modifications considerably boost structural stability and durability, achieving an impressive capacity retention of 83.4% and a minimal voltage decay of 1.49 m V per cycle after 150 cycles at 1 C. These findings provide crucial mechanistic insights into the role of surface modifications and guide the development of high-capacity cathodes with enhanced cyclability.

Suppress oxygen evolution of lithium-rich manganese-based cathode materials via an integrated strategy

Improving the reversibility of anionic redox and inhibiting irreversible oxygen evolution are the main challenges in the application of high reversible capacity Li-rich Mn-based cathode materials.A facile synchronous lithiation strategy combining the advantages of yttrium doping and LiYO_(2) surface coating is proposed.Yttrium doping effectively suppresses the oxygen evolution during the delithiation process by increasing the energy barrier of oxygen evolution reaction through strong Y–O bond energy.LiYO_(2) nanocoating has the function of structural constraint and protection,that protecting the lattice oxygen exposed to the surface,thus avoiding irreversible oxidation.As an Li^(+) conductor,LiYO_(2) nano-coating can provide a fast Li^(+) transfer channel,which enables the sample to have excellent rate performance.The synergistic effect of Y doping and nano-LiYO_(2) coating integration suppresses the oxygen release from the surface,accelerates the diffusion of Li^(+)from electrolyte to electrode and decreases the interfacial side reactions,enabling the lithium ion batteries to obtain good electrochemical performance.The lithium-ion full cell employing the Y-1 sample(cathode)and commercial graphite(anode)exhibit an excellent specific energy density of 442.9 Wh kg^(-1) at a current density of 0.1C,with very stable safety performance,which can be used in a wide temperature range(60 to-15℃)stable operation.This result illustrates a new integration strategy for advanced cathode materials to achieve high specific energy density.

Oxygen redox chemistry in lithium-rich cathode materials for Li-ion batteries:Understanding from atomic structure to nano-engineering

Lithium-rich oxide compounds have been recognized as promising cathode materials for high performance Li-ion batteries,owing to their high specific capacity.However,it remains a great challenge to achieve the fully reversible anionic redox reactions to realize high capacity,high stability,and low voltage hysteresis for lithiumrich cathode materials.Therefore,it is critically important to comprehensively understand and control the anionic redox chemistry of lithium-rich cathode materials,including atomic structure design,and nano-scale materials engineering technologies.Herein,we summarize the recent research progress of lithium-rich cathode materials with a focus on redox chemistry.Particularly,we highlight the oxygen-based redox reactions in lithium-rich metal oxides,with critical views of designing next generation oxygen redox lithium cathode materials.Furthermore,we purposed the most promising strategies for improving the performances of lithium-rich cathode materials with a technology-spectrum from the atomic scale to nano-scale.

Stabilized cobalt-free lithium-rich cathode materials with an artificial lithium fluoride coating

Iron-substituted cobalt-free lithium-rich manganese-based materials,with advantages of high specific capacity,high safety,and low cost,have been considered as the potential cathodes for lithium ion batteries.However,challenges,such as poor cycle stability and fast voltage fade during cycling under high potential,hinder these materials from commercialization.Here,we developed a method to directly coat LiF on the particle surface of Li_(1.2)Ni_(0.15)Fe_(0.1)Mn_(0.55O2).A uniform and flat film was successfully formed with a thickness about 3 nm,which can effect-ively protect the cathode material from irreversible phase transition during the deintercalation of Li^(+).After surface coating with 0.5wt%LiF,the cycling stability of Li_(1.2)Ni_(0.15)Fe_(0.1)Mn_(0.55O2) cycled at high potential was significantly improved and the voltage fade was largely suppressed.

Phase Transformation of Lithium-rich Oxide Cathode in Full Cell and its Suppression by Solid Electrolyte Interphase on Graphite Anode

Lithium-rich oxide is one of the most promising cathodes that meet high energy density requirement for batteries of the future, but its phase transformation from layer to spinel structure caused by the lattice instability presents severe challenge to cycling stability and the actually accessible capacity. The currently available approaches to suppress this undesired irreversible process often resort to limit the high voltages that lithium-rich oxide is exposed to. However, cycling stability thus improved is at the expense of the eventual energy output. In this work, we identified a new mechanism that is directly responsible for the lithium-rich oxide phase transformation and established a clear correlation between the successive consumption of Li+on anode due to incessant interphase repairing and the over-delithiation of lithium-rich oxide cathode. This new mechanism enables a simple but effective solution to the cathode degradation, in which an electrolyte additive is used to build a dense and protective interphase on anode with the intention to minimize Li depletion at cathode. The application of this new interphase effectively suppresses both electrolyte decomposition at anode and the phase transformation of lithium-rich oxide cathode, leading to high capacity and cycling stability.

Optimize two-phase distribution of lithium-rich materials to stabilize structure and suppress voltage attenuation

Lithium-rich materials possess the ultra-high specific capacity,but the redox of oxygen is not completely reversible,resulting in voltage attenuation and structural instability.A stepwise co-precipitation method is used for the first time in this paper to achieve the control of the two-phase distribution through controlling the distribution of transition metal elements and realize the modification of particle surface structure without the aid of heterologous ions.The results of characterization tests show that the content of LiMO_(2) phase inside the particles and the content of Li_(2)MnO_(3) phase on the surface of the particles are successfully increased,and the surface induced formation of Li_(4)Mn_(5)O_(12) spinel phase or some disorderly ternary.The electrochemical performance of the modified sample is as follows:LR(pristine)shows specific discharge capacity of 72.7 mA·h·g^(−1)after 500 cycles at 1 C,while GR(modified sample)shows specific discharge capacity of 137.5 mA·h·g^(−1) at 1 C,and the discharge mid-voltage of GR still remains above 3 V when cycling to 220 cycles at 1 C(mid-voltage of LR remains above 3 V when cycling to 160 cycles at 1 C).Therefore,deliberately regulating the local state of the two phases is a successful way to reinforced the material structure and inhibition the voltage attenuation.

Facet-dependent Thermal and Electrochemical Degradation of Lithium-rich Layered Oxides

Lithium-rich layered oxides(LLOs)are promising candidate cathode materials for safe and inexpensive high-energy-density Li-ion batteries.However,oxygen dimers are formed from the cathode material through oxygen redox activity,which can result in morphological changes and structural transitions that cause performance deterioration and safety concerns.Herein,a flake-like LLO is prepared and aberration-corrected scanning transmission electron microscopy(STEM),in situ high-temperature X-ray diffraction(HT-XRD),and soft X-ray absorption spectrum(sXAS)are used to explore its crystal facet degradation behavior in terms of both thermal and electrochemical processes.Void-induced degradation behavior of LLO in different facet reveals significant anisotropy at high voltage.Particle degradation originates from side facets,such as the(010)facet,while the close(003)facet is stable.These results are further understood through ab initio molecular dynamics calculations,which show that oxygen atoms are lost from the{010}facets.Therefore,the facet degradation process is that oxygen molecular formed in the interlayer and accumulated in the ab plane during heating,which result in crevice-voids in the ab plane facets.The study reveals important aspects of the mechanism responsible for oxygen-anionic activity-based degradation of LLO cathode materials used in lithium-ion batteries.In particular,this study provides insight that enables precise and efficient measures to be taken to improve the thermal and electrochemical stability of an LLO.

Dynamically lithium-compensated polymer artificial SEI to assist highly stable lithium-rich manganese-based anode-free lithium metal batteries

Owing to the unique structure,anode-free lithium metal batteries(AFLMBs)have higher energy density and lower production cost than traditional lithium metal batteries(LMBs)or lithium-ion batteries(LIBs),However,AFLMBs suffer from an inherently finite Li reservoir and exhibit poor cycle stability,low Coulombic efficiency(CE)and severe dendrite growth.In this work,polydiallyl lithium disulfide(PDS-Li)was successfully synthesized and coated on Cu current collector by electrochemical polymerization.The PDS-Li acts as an additional lithium resource to compensate for the irreversible loss of lithium during cycling.In addition,the special structure and lithiophilicity of PDS-Li contribute to lower nucleation overpotential and uniform lithium deposition.When coupled with Li-rich manganese-based(LRM)cathode of Li1.2Mn0.54Ni0.13Co0.13O2,the anode-free full cell exhibits significantly improved cycle stability over 100 cycles and capacity retention of 63.3%and 57%after 80 and 100 cycles,respectively.We believe that PDS-Li can be used to ensure stable cycling performance and high-energy-density in AFLMBs.

Origin of enhanced electrochemical performance in lithium-rich cathode materials via the fast ion conductor Li_(2)O-B_(2)O_(3)-LiBr

Lithium-rich cathode materials have garnered significant attention in the energy sector due to their high specific capacity.However,severe capacity degradation impedes their large-scale application.The employment of fast ion conductors for coating has shown potential in improving their electrochemical performance,yet the structural and chemical mechanisms underlying this improvement remain unclear.In this study,we systematically analyze,through first-principles calculations,the mechanism by which Li_(2)O-B_(2)O_(3)-LiBr(Hereafter referred to as LBB)coating enhances the electrochemical performance of the lithium-rich layered cathode material 0.5Li2MnO3·0.5LiNi1/3Co1/3Mn1/3O2(Hereafter referred to as OLO).Our calculations reveal that the LBB coating introduces a more negative valence charge(average−0.14 e)around the oxygen atoms surrounding transition metals,thereby strengthening metal-oxygen interactions.This interaction mitigates irreversible oxygen oxidation caused by anionic redox reactions under high voltages,reducing irreversible structural changes during battery operation.Furthermore,while the migration barrier for Li+in OLO is 0.61 eV,the LBB coating acts as a rapid conduit during the Li+deintercalation process,reducing the migration barrier to 0.32 eV and slightly lowering the internal migration barrier within OLO to 0.43 eV.Calculations of binding energies to electrolyte byproducts HF before and after coating(at−7.421 and−3.253 eV,respectively)demonstrate that the LBB coating effectively resists HF corrosion.Subsequent electrochemical performance studies corroborated these findings.The OLO cathode with a 2%LBB coating exhibited a discharge capacity of 157.12 mAh g^(−1) after 100 cycles,with a capacity retention rate of 80.38%,whereas the uncoated OLO displayed only 141.67 mAh g^(−1) and a 72.45%capacity retention.At a 2 C rate,with the 2 wt%LBB-coated sample maintaining a discharge capacity of 140.22 mAh g^(−1) compared to only 107.02 mAh g^(−1) for the uncoated OLO.

Geochronology and geochemistry of lithium-rich tuffs in the Sichuan basin,western Yangtze:Implication for the magmatic origin and final closure of eastern Paleo-Tethys

The felsic volcanogenic tuffs named"green-bean rocks"(GBRs),characterized by a green or yellowish green color,are widely distributed in the western Yangtze platform and have a high lithium content(286-957 ppm).This paper studies the ages,origin and tectonic setting of the GBRs in the Sichuan basin on the western margin of the Yangtze platform through the whole-rock geochemistry and zircon trace elements by using U-Pb dating and Hf-O isotopes.The GBR samples from the Quxian and Beibei sections yielded zircon U-Pb ages of 245.5±1.8 Ma and 244.8±2.2 Ma.These samples can be used as the isochronous stratigraphic marker of the Early-Middle Triassic boundary(EMTB)for regional correlation.The whole-rock and zircon geochemistry,and zircon Hf-O isotopes exhibited S-type geochemical affinities with high positiveδ^(18)0 values(9.28‰-11.98‰),low negativeε_(Hf)(t)values(-13.87 to-6.79),and T_(DM)^(2)ages of 2150-1703 Ma,indicating that the lithium-rich GBRs were generated by the remelting of the pre-existing ancient Paleoproterozoic layer without mantle source contamination in the arcrelated/orogenic tectonic setting.The results of this study demonstrate that the lithium-rich GBRs in the western Yangtze platform were derived from arc volcanic eruptions along the Sanjiang orogen,triggered by the closure of the eastern Paleo-Tethys Ocean and the syn-collision between the continental Indochina and Yangtze blocks at ca.247 Ma.This was marked by a major shift from I-type magmas with intermediateε_(Hf)(t)values to S-type magmas with low negativeε_(Hf)(t)values.Collectively,our results provide new insights into the origin of the GBRs and decodes the closure of the eastern Paleo-Tethys.

High-capacity lithium-rich cathode oxides with multivalent cationic and anionic redox reactions for lithium ion batteries

Lithium-rich cathode oxides with capability to realize multivalent cationic and anionic redox reactions have attracted much attention as promising candidate electrode materials for high energy density lithium ion batteries because of their ultrahigh specific capacity. However, redox reaction mechanisms, especially for the anionic redox reaction of these materials, are still not very clear. Meanwhile, several pivotal challenges associated with the redox reactions mechanisms, such as structural instability and limited cycle life, hinder the practical applications of these high-capacity lithium-rich cathode oxides. Herein, we review the lithium-rich oxides with various crystal structures. The multivalent cationic/anionic redox reaction mechanisms of several representative high capacity lithium-rich cathode oxides are discussed, attempting to understand the origins of the high lithium storage capacities of these materials. In addition, we provide perspectives for the further development of these lithium-rich cathode oxides based on multivalent cationic and anionic redox reactions, focusing on addressing the fundamental problems and promoting their practical applications.

Challenges and strategies of lithium-rich layered oxides for Li-ion batteries

Lithium-ion batteries are considered a promising energy storage technology in portable electronics and electric vehicles due to their high energy density,competitive cost,and environmental friendliness.Improving cathode materials is an effective way to meet the demand for better batteries,of which the utilization of high-voltage cathode materials is an important development trend.In recent years,lithium-rich layered oxides have gained great attention due to their desirable energy density.This review presents the relationships between lattice structure and electrochemical properties,the underlying degradation mechanisms,and corresponding modification strategies.The recent progress and strategies are then highlighted,including element doping,surface coating,morphology design,size control,etc.Finally,a concise perspective for future developments and practical applications of lithium-rich layered oxides has been provided.

Electrospinning synthesis of novel lithium-rich 0.4Li2MnO3.0.6LiNi1/3CO1/3Mn1/3O2 nanotube and its electrochemical performance as cathode of lithium-ion battery

In this study, a lithium-rich 0.4Li2MnO3.0.6LiNi1/3Co1/3Mn1/3O2 nanotube layered cathode synthesized by novel electrospinning is reported, and the effects of temperature on the electrochemical performance and morphologies are investigated. The crystal structure is characterized by X-ray diffraction patterns, and refined by two sets of diffraction data （R-3m and C2/m）. Refined crystal structure is 0.4Li2MnO3.0.6LiNi1/3COl/3Mn13O2 compos- ite. The inductively coupled plasma optical emission spec- trometer and thermogravimetric and differential scanning calorimetry analysis measurement supply reference to opti- mize the calcination temperature and heat-treatment time. The morphology is characterized by scanning and high- resolution transmission electron microscope techniques, and the micro-nanostructured hollow tubes of Li-rich 0.4Li2MnO3-0.6LiNil/3COl/3Mn1/3O2 composite with outer diameter of 200-400 nm and the wall thickness of 50-80 nm are synthesized successfully. The electrochemical evaluation shows that 0.4Li2MnO3.0.6LiNi1/3Cov3Mn1/3O2 sintered at 800 ℃ for 8 h delivers the highest capacity of the first dis- charge capacity of 267.7 mAh/g between 2.5 V and 4.8 V at 0.1C and remains 183.3 mAh/g after 50 cycles. The electro- spinning method with heat-treatment to get micro-nanos- tructured lithium-rich cathode shows promising application inlithium-ion batteries with stable electrochemical performance and higher C-rate performance for its shorter Li ions transfer channels and stable designed structure.

Suppression of voltage decay through adjusting tap density of lithium-rich layered oxides for lithium ion battery

The voltage decay of lithium-rich layered oxides(LLOs)is still one of the key challenges for their application in commercial battery although these materials possess the advantages of high specific capacity and low cost.In this work,the relationship between voltage decay and tap density of LLOs has been focused.The voltage decay can be significantly suppressed with the increasing tap density as well as the homogenization of the primary or secondary particle size of agglomerated spherical LLOs.Experimental results have shown that an extreme small voltage decay of 0.98 m V cycle^(-1)can be obtained through adjusting the tap density of agglomerated spherical LLOs to 1.99 g cm^(-3),in which the size of primary and secondary particles are uniform.Our work offers a new insight towards the voltage decay and capacity fading of LLOs through precursor preparation process,promoting their application in the real battery in the future.

川西巴塘地区富锂温泉的同位素特征及其成因探讨

川西巴塘地区处于青藏高原东南缘,是地壳新构造运动活跃、地震活动强烈而密集的地区,其中茶洛—德达地段是温泉聚集区,富锂沸泉与温泉密集发育。为进一步认识该区富锂温泉的成因以及温泉与地震活动的关系,开展了温泉水氢、氧、碳和锂同位素的综合研究,阐明了地热流体、锂和热量的来源,探讨了富锂温泉的成因及其与地震活动的关系,为该区富锂温泉的研究和勘查提供支撑。研究结果显示:1)茶洛—德达地段发育章柯、茶洛富锂沸泉和查青卡富锂温泉,锂含量高达1353.00~3592.00µg·L^(-1),其锂同位素组成δ7Li介于-0.53‰~1.74‰之间;2)该区富锂温泉水主要来源于周边4800~5200 m的高山区域大气降水,温泉流体循环深度可达6900~8500 m,与该区部分地震的震源深度相当;3)富锂温泉的深部发生较强的高温(温度236~289℃)水-岩反应,碳酸盐岩、富锂花岗岩等释放出碳和锂等元素,形成查青卡富锂温泉(1353~1392µg·L^(-1));章柯、茶洛沸泉除上述锂来源外,还有深部高温富锂流体混入,从而形成更高温(240~289℃)、更富锂(2736~3592µg·L^(-1))的地热流体;4)该区章柯、茶洛富锂沸泉的热源除以深部(地壳、地幔)热流为主要热源外,还有地震断层摩擦热、深部流体热为补充热源,频发的地震活动持续地、脉动式地为章柯、茶洛地热系统补充热量,形成富锂沸泉。查青卡富锂温泉热源主要为深部(地壳、地幔)热流,无断层摩擦热和深部流体热补充。

A Facile Li_(2)TiO_(3) Surface Modification to Improve the Structure Stability and Electrochemical Performance of Full Concentration Gradient Li-Rich Oxides

Full concentration gradient lithium-rich layered oxides are catching lots of interest as the next generation cathode for lithium-ion batteries due to their high discharge voltage,reduced voltage decay and enhanced rate performance,whereas the high lithium residues on its surface impairs the structure stability and long-term cycle performance.Herein,a facile multifunctional surface modification method is implemented to eliminate surface lithium residues of full concentration gradient lithium-rich layered oxides by a wet chemistry reaction with tetrabutyl titanate and the post-annealing process.It realizes not only a stable Li_(2)TiO_(3)coating layer with 3D diffusion channels for fast Li^(+)ions transfer,but also dopes partial Ti^(4+)ions into the sub-surface region of full concentration gradient lithium-rich layered oxides to further strengthen its crystal structure.Consequently,the modified full concentration gradient lithium-rich layered oxides exhibit improved structure stability,elevated thermal stability with decomposition temperature from 289.57℃to 321.72℃,and enhanced cycle performance(205.1 mAh g^(-1)after 150 cycles)with slowed voltage drop(1.67 mV per cycle).This work proposes a facile and integrated modification method to enhance the comprehensive performance of full concentration gradient lithium-rich layered oxides,which can facilitate its practical application for developing higher energy density lithium-ion batteries.

单晶高镍三元正极材料的制备及改性研究进展

介绍了单晶高镍三元正极材料的结构特点,总结了单晶高镍三元正极材料常见的制备工艺,并探讨了近年来材料性能改善的主要策略,可为高性能单晶高镍三元正极材料的规模化生产提供借鉴和参考。

层状富锂锰基正极材料包覆改性的最新进展

首先综述了富锂锰基材料的结构和循环过程中存在的问题,然后介绍了富锂锰基正极材料包覆改性研究的最新进展,系统描述了电化学活性材料、非电化学活性材料和导电聚合物等不同种类包覆物质及单层包覆、双层复合包覆和原位包覆等包覆方法在该材料改性领域中的应用,进一步从材料结构、失效机制等角度深入分析了各种包覆改性方法及包覆物质改善富锂锰基材料循环性能的作用机制.最后,对Li_(1.2)Mn_(0.54)Ni_(0.13)Co_(0.13)O_(2) (LMNC)材料及改性方法等未来发展方向进行了展望.

青藏高原中部班戈错富锂盐湖水位月际变化与驱动因素分析

锂在新能源领域的独特优势使其需求规模呈爆发式增长,世界各主要经济体将其列为关键矿产。西藏盐湖锂资源丰富,水位变化是锂资源动态评价的重要环节,班戈错是典型富锂盐湖,极具代表性。本文以2016—2023年班戈错现场实测水文及气象观测资料为基础,分析了水位月际变化特征及驱动因素。主要结论如下:(1)以2018年6月、2021年12月为界,2016年1月至2023年7月,班戈错水位月际变化剧烈,经历下降—上升—下降波动变化过程,且水位上升速度远大于水位下降速度。(2)蒸发量增大是班戈错两次水位波动下降的主要原因;而蒸发量降低和温度升高是驱动水位波动上升的动力。(3)温度及降水是控制湖泊年内变化的主导因子,且温度主要通过控制蒸发来实现影响。研究结果为青藏高原月际尺度气候变化的盐湖区域响应和班戈错将来开采过程中锂资源保障程度研究提供数据基础。

富锂正极材料Li_(1.2)Ni_(0.13)Co_(0.13)Mn_(0.54)O_(2)的制备及性能

为满足当前新能源发电技术对高比容量电化学储能材料的需求,采用聚合物热解法,通过优化前体聚合过程中金属离子与丙烯酸配比制备高比容量层状富锂锰基氧化物Li_(1.2)Ni_(0.13)Co_(0.13)Mn_(0.54)O_(2)。依据丙烯酸聚合反应实现金属离子均匀分散,通过二次升温煅烧制备出富锂锰基正极材料Li_(1.2)Ni_(0.13)Co_(0.13)Mn_(0.54)O_(2)。改变煅烧温度,制备不同煅烧温度下的正极材料样品,研究煅烧温度对其微观形貌及电化学性能的影响。利用X射线衍射(XRD)、扫描电镜(SEM)测试技术观测不同材料样品微观形貌和晶体结构的差异,利用能谱分析技术(EDS)观察材料中的元素分布情况,使用新威电池测试系统和电化学工作站对所制备正极材料的电化学性能进行研究。结果表明,在925℃下制备的Li_(1.2)Ni_(0.13)Co_(0.13)Mn_(0.54)O_(2)正极材料结晶度高,层状结构明显,阳离子混排程度低,各元素分散均匀。在2.0~4.8 V范围循环充放电测试,0.1C倍率下首周放电比容量达到290.3 mAh/g,0.5C倍率下循环充放电100周放电容量保持在204.8 mAh/g,容量保持率为81.9%,具有较好的循环稳定性。本实验制备出的富锂锰基正极材料Li_(1.2)Ni_(0.13)Co_(0.13)Mn_(0.54)O_(2)具有良好的电化学性能,有助于推动富锂锰基正极材料的应用,为高比容量正极材料的发展提供实验依据。