A Review:Pre-lithiation Strategies Based on Cathode Sacrificial Lithium Salts for Lithium-Ion Capacitors

Similar to lithium-ion batteries(LIBs),during the first charge/discharge process of lithium-ion capacitors(LICs),lithium-intercalated anodes(e.g.,silicon,graphite,and hard carbon)also exhibit irreversible lithium intercalation behaviors,such as the formation of a solid electrolyte interface(SEI),which will consume Li^(+)in the electrolyte and significantly reduce the electrochemical performance of the system.Therefore,pre-lithiation is an indispensable procedure for LICs.At present,commercial LICs mostly use lithium metal as the lithium source to compensate for the irreversible capacity loss,which has the demerits of operational complexity and danger.However,the pre-lithiation strategy based on cathode sacrificial lithium salts(CSLSs)has been proposed,which has the advantages of low cost,simple operation,environmental protection,and safety.Therefore,there is an urgent need for a timely and comprehensive summary of the application of CSLSs to LICs.In this review,the important roles of pre-lithiation in LICs are detailed,and different pre-lithiation methods are reviewed and compared systematically and comprehensively.After that,we systematically discuss the pre-lithiation strategies based on CSLSs and mainly introduce the lithium extraction mechanism of CSLSs and the influence of intrinsic characteristics and doping amount of CSLSs on LICs performance.In addition,a summary and outlook are conducted,aiming to provide the essential basic knowledge and guidance for developing a new pre-lithiation technology.

Studies on the Thermodynamics and Thermal Chemistry Properties for Lithium Salts and Their Aqueous Solution Systems

1 Introduction With the industrial development of lithium battery,nuclear and aerospace industry,the demands of metal lithium and its compounds are increasing significantly.Lithium is called as the energy of the metal in the new century(Zhang et al.2001).The total reserve of lithium resources around the world7

Effect of the anionic composition of sulfolane based electrolytes on the performances of lithium-sulfur batteries

In lithium-sulfur batteries,cell design,specifically electrolyte design,has a key impact on the battery performance.The effect of lithium salt anion donor number(DN)(DN[PF_(6)]^(-)=2.5,DN[N(SO_(2)CF_(3))_(2)]^(-)=5.4,DN[ClO_(4)]^(-)=8.4,DN[SO_(3)CF_(3)]^(-)=16.9,and DN[NO_(3)]^(-)=21.1)on the patterns of lithium-sulfur batteries and lithium metal electrode performances with sulfola ne-based electrolytes is investigated.An increase in DN of lithium salt anions leads to an increase in the depth and rate of electrochemical reduction of sulfur and long-chain lithium polysulfides and to a decrease in those for medium-and short-chain lithium polysulfides.DN of lithium salt anions has weak effect on the discharge capacity of lithium-sulfur batteries and the Coulomb efficiency during cycling,with the exception of LiSO_(3)CF_(3)and LiNO_(3).An increase in DN of lithium salt anions leads to an increase in the cycling duration of lithium metal anodes and to a decrease in the presence of lithium polysulfides.In sulfolane solutions of LiNO_(3)and LiSO_(3)CF_(3),lithium polysulfides do not affect the cycling duration of lithium metal anodes.

Effects of conductive agent type on lithium extraction from salt lake brine with LiFePO_(4) electrodes

Electrochemical lithium extraction from salt lakes is an effective strategy for obtaining lithium at a low cost.Nevertheless,the elevated Mg:Li ratio and the presence of numerous coexisting ions in salt lake brines give rise to challenges,such as prolonged lithium extraction periods,diminished lithium extraction efficiency,and considerable environmental pollution.In this work,Li FePO4(LFP)served as the electrode material for electrochemical lithium extraction.The conductive network in the LFP electrode was optimized by adjusting the type of conductive agent.This approach resulted in high lithium extraction efficiency and extended cycle life.When the single conductive agent of acetylene black(AB)or multiwalled carbon nanotubes(MWCNTs)was replaced with the mixed conductive agent of AB/MWCNTs,the average diffusion coefficient of Li+in the electrode increased from 2.35×10^(-9)or 1.77×10^(-9)to 4.21×10^(-9)cm^(2)·s^(-1).At the current density of 20 mA·g^(-1),the average lithium extraction capacity per gram of LFP electrode increased from 30.36 mg with the single conductive agent(AB)to 35.62 mg with the mixed conductive agent(AB/MWCNTs).When the mixed conductive agent was used,the capacity retention of the electrode after 30 cycles reached 82.9%,which was considerably higher than the capacity retention of 65.8%obtained when the single AB was utilized.Meanwhile,the electrode with mixed conductive agent of AB/MWCNTs provided good cycling performance.When the conductive agent content decreased or the loading capacity increased,the electrode containing the mixed conductive agent continued to show excellent electrochemical performance.Furthermore,a self-designed,highly efficient,continuous lithium extraction device was constructed.The electrode utilizing the AB/MWCNT mixed conductive agent maintained excellent adsorption capacity and cycling performance in this device.This work provides a new perspective for the electrochemical extraction of lithium using LFP electrodes.

NMR Studies on Diffusion and Molecular Motions of Imidazolium Ionic Liquids doped by Lithium Salts Related to Ionic Conductivity and Computational Interaction Energy

1 Results Room-temperature Ionic liquids (RTILs) are special class of compounds, where a combination of cations and anions produces neutral, stable and viscous liquids with high ionic conductivity. Widely spread applications are proposed to use conductors, electrolytes, clean solvents and others. Especially, RTILs are expected to be safe electrolytes in the ion-lithium batteries. In this study, NMR methods are used to clarify the basic properties of the individual movements of the anions and cations of ...

The Phase Diagram of Lithium Salt Systems and Its Application in Extraction of Lithium from Salt Lake Brine

At present,the extraction of lithium from salt lake brine is the new trend of the salt lake industrialization.The saltine lake lithium resources are extremely rich in western china,especially in Qinghai-Tibetan plateau.Brine of salt

Synthesis and Structural Characterizations of a New Lithium Salt for Lithium-ion Batteries

A novel crystal [（CH3O）2CO]3Li2[C2BF2O4]2 was synthesized and fully characterized by FT-IR and single-crystal X-ray diffraction analysis. It crystallizes in monoclinic system, P2Jn space group, with a = 8.1749（2）, b = 10.7449（2）, c = 12.8665（3） A, βl = 94.654（2）°, V= 1126.45（4） A3, Z = 2, Dc = 1.644 g/cm, F（000） = 568, p = 1.498 mm^-1, Mr= 557.77 g/mol, the final R = 0.0334 and wR = 0.0903. The structure analysis revealed that each Li atom is three-coordinated and adopts 1.5 O atoms of two different dimethyl carbonates and one O atom of C2BF2O4-. Thermal stability and infrared spectra analysis were studied and discussed.

Effect of Cerium on Behavior of Lithium-Alu-minium Anode

The influence of cerium on the behavior of lithiumaluminium alloy anode was studied. The discharge capacity and voltage of lithium-aluminium anode can be enhanced by adding 0.5%-1.5% Ce and the surface quality of the anode can also be improved. The porous LiAI-Ce alloy anode has the best charge and discharge properties.

Lithium Ion Extraction from the High Ration Mg/Li Salt Lake Brine with Ionic Liquid in Triisobutyl Phosphate and Kerosene

1 Introduction As the lightest metal with the unique properties of energy production and storage,lithium is regarded as the new century energy metal.Lithium and its compounds were widely used in various industrial fields,especially in

LITHIUM RESOURCES IN CHINA'S SALT LAKES & ITS SUSTAINABLE DEVELOPMENT

This article gives an introductory exposition of the growing demands of lithium on the market against the background of current rapid S&Tprogress and booming economic development, the worldwide trend in the production of lithium salts and the rich lithium reserves in China’s salt lakes as well as the brilliant prospects for its exploitation in the future. The article proposes that a sustainable exploitation of the lithium trove from these salt lakes should be rooted in comprehensive utilization of the trove and take a long-term approach, emphasizing high value proliferation in developing quality lithium-based products. Also, it expresses some tentative ideas on building demonstration bases for all-round exploitation and utilization of the salt lake resources and the development of lithium cells.

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).

Performance degradation mechanism of lithium compounds ceramic fuel cell with GDC as electrolyte

The performance degradation mechanism of ceramic fuel cell with NCAL(Ni_(0.8)Co_(0.15)Al_(0.05)LiO_(2))as symmetrical electrode and GDC as electrolyte in H2 is investigated.It is found that under the condition of 550◦C and constant current density of 0.2 A⋅cm^(-2),the output voltage of the cell is about 1.005 V in the initial 10 h and remains relatively stable.After 10 h,the voltage of the cell began to decrease gradually,and by 50 h,the voltage had decreased to 0.522 V.The results testing electrochemical performance of the cell and characterizing the cell materials before and after test using SEM,TOF-SIMS and FTIR indicate that the distribution of Li_(2)O/LiOH/Li_(2)CO_(3)compounds generated from NCAL anode in the cell plays a vital role in significantly improving the ionic conductivity of electrolyte and gas tightness of the cell.The dynamic migration of molten salt destroyed the continuity of molten salt in the cell,which in turn adversely impacted the ionic conductivity of electrolyte,gas tightness of the cell,and electrochemical reactions on both sides of the cathode and anode.These finally lead to the degradation of the cell performance.

Ion transport and structural design of lithium-ion conductive solid polymer electrolytes:a perspective

Solid polymer electrolytes(SPEs)possess several merits including no leakage,ease in process,and suppressing lithium dendrites growth.These features are beneficial for improving the cycle life and safety performance of rechargeable lithium metal batteries(LMBs),as compared to conventional non-aqueous liquid electrolytes.Particularly,the superior elasticity of polymeric material enables the employment of SPEs in building ultra-thin and flexible batteries,which could further expand the application scenarios of high-energy rechargeable LMBs.In this perspective,recent progresses on ion transport mechanism of SPEs and structural designs of electrolyte components(e.g.conductive lithium salts,polymer matrices)are scrutinized.In addition,key achievements in the field of single lithium-ion conductive SPEs are also outlined,aiming to provide the status quo in those SPEs with high selectivity in cationic transport.Finally,possible strategies for improving the performance of SPEs and their rechargeable LMBs are also discussed.

Determination of anions in lithium-ion batteries electrolyte by ion chromatography

A sensitive and accurate method based on ion chromatography was established for determination of five lithium salts in lithium-ion batteries electrolytes. Chromatographic analyses were carried out on an anion exchange column at flow rate of 1 m L/min. Under the optimal conditions, five target anions（BF4^-,PF6^-, TFSI^-, BOB^-and FSI^-） exhibited satisfactory linearity with a correlation coefficient of 0.9996. The relative standard derivations of the target anions were less than less than 0.94%（n = 7）. The limits of detections were in the range of 0.068–0.29 mg/L with average spiked recoveries ranging from 96.8% to 105.1%.

Metastable Phase Equilibrium in the Reciprocal Quaternary System LiCl＋MgCl2＋Li2SO4＋MgSO4＋H2O at 348.15 K and 0.1 MPa

The metastable solubilities and the physicochemical properties including density and pH of the reciprocal quaternary system（LiCl＋MgCl2＋Li2SO4＋MgSO4＋H2O） at 348.15 K and 0.1 MPa were determined using the isother- mal evaporation method. The dry-salt diagram and water-phase diagram were plotted based on the experimental data. There are five invariant points, eleven tmivariant curves, and seven crystallization zones corresponding to hexahy- drite, tetrahydrite, kieserite, bischofite, lithium sulfate monohydrate, lithium chloride monohydrate and lithium car- nallite. Comparison between the stable and metastable diagrams at 348.15 K indicates that the metastable phenome- non of magnesium sulfate is obvious, and the crystallization regions of hexahydrite and tetrahydrite disappear in the stable phase diagram. A comparison of the metastable dry-salt phase diagrams at 308.15, 323.15 and 348.15 K shows that with the increasing of temperatttre the epsomite crystallization zone disappears from the dry-salt phase diagranl of 303.15 K, and a new kieserite crystallization zone is presented at 348.15 K. The density and pH in the metastable equilibrium solution present regular change with the increasing of Janecke index J（2Li＋）, and the calculated densities using the empirical equation agree well with the experimental values.

Recovering the electrochemical window by forming a localized solvation nanostructure in ionic liquids with trace water

Motivated by the fascinating merits of wide electrochemical stability window(ESW)and nonflammability,ionic liquids(ILs)have been utilized as advanced electrolytes in various emerging electrochemical energy storage technologies.However,ILs are hygroscopic to the water in the air and the presence of trace water will narrow the ESW of ILs.In this article,we report that a localized solvation nanostructure(LSNS)is formed in ILs,which plays an important role in fully recovering the originally decreased ESW of[EMIM][TFSI]IL owing to the trace water.Such LSNS is consisted of Li^(+)ions with water molecules as the center,TFSI-anions as the secondary periphery and EMIM^(+)cations as the outermost layer after adding the proper amount of LiTFSI.This nanostructure can restrain the possibility of trace water to approach the electrode/electrolyte interfaces and adverse redox reactions,thereby recovering the ESW.Moreover,the effectiveness of this strategy in different kinds of ILs to fully recover ESW decreasing is verified.This article comes up with a feasible method to eliminate the trace water caused ESW drop for ILbased electrolytes and provides a new insight for understanding the molecular-level interaction between different ions in ILs with water molecules.