Electrochemical impedance spectroscopy, or EIS, is one of the most powerful tools to analyze electrochemical processes occurring at electrode/electrolyte interfaces, and has been widely applied to the analysis of the insertion/desertion process of lithium ion in the intercalation electrode for lithium ion battery. In this paper, the ascription of each time constant of the EIS spectra is discussed, based on the analysis of the common EIS features of intercalation electrode. The kinetic parameters in the lithium ion insertion/desertion，dependent on temperature and electrode polarization, such as the charge transfer resistance, the electronic resistance of activated material, the resistance of SEI film that lithium ion transferring through, are also discussed based on the theoretical analysis.

Contents
1 Introduction
2 The common EIS features of intercalation electrode
3 The analysis of electrochemical impedance spectroscopy
3.1 The analysis of high-frequency arc
3.2 The analysis of medium to high-frequency arc
3.3 The analysis of medium -frequency arc
3.4 The analysis of low-frequency straight line
3.5 The analysis of the lowest-frequency domain
4 Conclusion

This paper reviews the relationship between synthesis, structures and properties of intercalation electrodes with layered LixMO2 and spinel LixM2O4 structures (M = Co、Ni、Mn、V ) as cathodes, and graphite, disordered carbon and metal oxide as anodes in Li ion batteries. Emphasisis focused on the structural properties of intercalation electrode materials which are related to the rechargeable capacity and stability during cycling of Li ions. 118 references are given.

The research progress of solid electrolyte interface (SEI) film in lithium ion balleries is reviewed. Based on the mechanism and models of SEI, the possible effect factors on the SEI film and its modification methods are given. The applications of different analysis technology, especially the in. situ analysis technology are discussed. The SEI film formed on cathode surface and the interaction between electrodes based on aqueous binding materials and electrolyte solu-tion would be the hotspot in the future.

Graphene, a one-atom layer of graphite, possesses unique two dimensional structure and excellent electrical, mechanical, and thermal properties. It is considered as one of the most promising candidates for the future electrode materials for lithium ion batteries. Since the microstructure of the electrode material has great influence on its performance, the synthesis of electrode materials with graphene is widely studied to obtain specific morphologies and microstructures with great electrochemical performance improvements. In this review, we highlight recent advancements in the studies of the graphene-containing materials used in lithium ion batteries. Graphene acts as not only a mechanically stable buffer to accommodate the volume effect during cycling, but also a conductive network to enhance the electric conductivity of the anode composite materials. The graphene-containing anode materials can exhibit better cycling and rate performances. Especially, when forming optimized microstructures, such as sandwich-like blocks or other well-controlled encapsulating structures, the graphene can significantly improve electrochemical properties of anode composite materials. A continuous 3D conductive network formed by graphene in the cathode composite materials can effectively improve the electron and ion transportation. Additionally, graphene used as the conductive additive can achieve better charge/discharge performance with a much lower adding amount than those of commercial carbon-based additives. A prospect for future research developments in this field is proposed at the end of this review. Contents
1 Introduction
2 Preparation of graphene
3 Application of graphene in anodes of lithium-ion batteries
3.1 Electrochemical properties of graphene
3.2 Composite materials based on graphene
4 Application of graphene in cathodes of lithium-ion batteries
5 Application of graphene as conductive additive
6 Conclusions and Outlook

The cathode (positive electrode) is the single (or major) donor of lithium ions in current lithium ion batteries. It is becoming the bottleneck to the increase of energy density and the decrease of cost of lithium ion batteries. This review presents the research progress in our laboratory in surface modification and structural designing of cathode materials after a brief introduction to the structures, the performance features and the main problems of some typical cathode materials.

As the important building blocks of lithium ion battery, cathode materials provide all extracting/inserting Lithium ions. Electrochemical performance of lithium ion battery is affected by the different way of Lithium ion migration in crystal structure of cathode materials. In this paper, the relationship of crystal structure, lithium ion migration way and electrochemical performance are reviewed in detail in terms of crystal structure: one-, two- and three-dimension. These cathode materials are mainly olivine-structured LiFePO₄，α-NaFeO₂ layered LiMO₂ (M=Co, Ni, Mn)，monoclinic structured Li_1+xV₃O₈，orthogonal structured Li₂MSiO₄ (M=Fe, Mn)，spinel structured LiMn₂O₄ and nascion structured Li₃V₂(PO₄)₃. Moreover，we discuss the present situation and challenges that remain regarding the lithium ion battery, and highlight ongoing research strategies on cathode materials.

Contents
1 Introduction
2 Lithium ion battery cathode materials
3 One-dimension cathode materials
3.1 Olivine-structured phosphates LiFePO₄
3.2 Electrochemical performance ameliorations
4 Two-dimension cathode materials
4.1 α-NaFeO₂ layered LiMO₂ (M=Co, Ni, Mn)
4.2 Monoclinic structured Li_1+xV₃O₈
4.3 Orthogonal structured Li₂MSiO₄ (M=Fe, Mn, Co)
5 Three-dimension cathode materials
5.1 Spinel structured LiMn₂O₄
5.2 NASCION structured Li₃V₂(PO₄)₃
6 Conclusion

Application of lithium ion battery (LIB) has been widely extended as its energy density is improved and its cost is reduced. Especially in recent years, significant attention has been paid to application of LIB in electric vehicles and energy storage. However, safety performance of LIB is considered as one of the major barriers which impede the expansion of these application fields. Since safety performance of LIB is fundamentally determined by thermal stability of materials for lithium-ion battery, this paper reviews recent research progress in this field. Among all of the safety tests, overcharge, hot box, nail penetration, crush and internal short are usually considered to be critical ones. This paper discusses major factors influencing these safety tests based on research results obtained in the authors'group. This paper also summarizes state-of-the-art approaches to improve safety performance of LIB in terms of battery materials, cell design and manufacturing.

Research progress of layered Li-Ni-Co-Mn-O as cathode materials for lithium ion batteries in recent years were reviewed and emphasis was replaced on their synthesis ways, electrochemical performance , as well as doped and surface-modification studies. Now LiNi_1/3Co_1/3Mn_1/3O₂has been commercialized and it will substitute LiCoO₂ finally because of its excellent characters and less cost.

Lithium-ion batteries (LIBs) are one of the important electrochemical power sources for low- or zero-emission hybrid electrical and electrical vehicles, energy-efficient cargo ships and locomotives, and aerospace in the modern society. The difficulties in mastering the electrode/electrolyte interface have slowed down the progress of LIBs. Interfacial processes of lithium ion batteries include mainly insertion/extraction of lithium ion, solvation/desolvation of lithium with solvents, formation and variation of solid electrolyte interphase (SEI) layer, and decomposition of electrolyte. Interfacial processes directly affect the efficiency of electrochemical energy conversion and storage, such as the cycling ability, the lifetime and the reversible capacity, as well as the safety issue of lithium ion batteries. The characterization of the interface processes at a molecular level by FTIR spectroscopy is one of the key subjects, as it is helpful for the improvement the performance of lithium ion batteries and development of non-aqueous theory. Recent progresses about the application of FTIR spectroscopy in lithium ion batteries are reviewed. This review put emphasis on: (a) the characterization of chemical composition and variation of SEI layer on cycled or aged electrode materials by ex situ FTIR spectroscopy, and (b) the investigation of decomposition of electrolyte, formation of SEI layer and the insertion/extraction of lithium ion by both in-situ FTIR reflection spectroscopy and in situ FTIR transmission spectroscopy.

One of the obstacles to commercialize high capacity and high power lithium-ion batteries is safety properties. The explosion of battery results from the heat and pressure accumulation by internal component reactions under abuse conditions, such as overheating, overcharge, short-circuit and so on. In this paper, the main heat sources are summarized, such as cathode and anode decomposition, electrolyte decomposition, the reaction between electrolyte and electrodes. The explosion mechanism of lithium-ion battery is analyzed under high temperature heat test, overcharge and short-circuit. The measures to improve battery safety are suggested.

Organosilicon compounds have attracted considerable interest as electrolytes for lithium-ion batteries because they are nontoxic, nonflammable, as well as have lower glass transition temperatures, lower vapor pressure and higher flash point than commercial alkyl carbonates. These compounds can improve the electrochemical performances and safety of lithium-ion batteries when used as electrolyte solvents or additives in the electrolytes. In this paper, the recent advances of organosilicon compounds both as electrolyte solvents and additives are reviewed. Organosilicon electrolytes containing ethylene oxide(EO) substituents with or without carbon spacer between silicon atom and EO unit are specially remarked as safe electrolytes. Organosilicon compounds as functional additives are also introduced in terms of the capabilities of passive film formation, flame-retardant, and acid/water scavenger.

Contents
1 Introduction
2 Organosilicon electrolyte solvents for lithium-ion batteries
2.1 Alkylsiloxane(Si—O) based electrolyte solvents
2.2 Alkylsilane(Si—C) based electrolyte solvents
2.3 Liquid oligomeric siloxane(—Si—O—Si—) based electrolyte solvents
3 Organosilicon electrolyte additives for lithium-ion batteries
3.1 Film-forming additives
3.2 Flame retardant additives
3.3 Acid and water scavenge additives
3.4 Low temperature and high output additives
3.4.1 Cyclic carbonate modified organosilicon compounds
3.4.2 Silane compounds containing EO group
4 Conclusions and outlook

The rechargeable lithium-ion battery has been extensively used in mobile communication and portable instruments due to its many advantages, such as high volumetric and gravimetric energy density and low self-discharge rate. In addition, it is the most promising candidate as the power source for (hybrid) electric vehicles and stationary energy storage. The properties of electrode/electrolyte interfaces play an important role in the electrochemical performance of the electrode material and a battery, such as the capacities, irreversible charge “loss”, rate capability and cyclability. In present paper, the methods to investigate the properties of electrode/electrolyte interfaces, for example, traditional electrochemical methods, microscopy methods, spectroscopic methods, electrochemical quartz crystal microgravimetry (EQCM) are summarized. The principles, advantages and disadvantages of these methods and their applications in investigating the properties of electrode/electrolyte interfaces, especially the progress in the combination of these methods to investigate the properties of electrode/electrolyte interfaces, are introduced in detail, and these methods will be considerable to study the new materials or the traditional materials for lithium-ion batteries in the future.

Silicon is one of the most attractive anode materials for lithium ion batteries on account of its low discharge potential and the highest theoretical capacity for lithium storage. However, the large volume effect, poor electronic conductivity and incompatibility with the conventional electrolyte hinder its commercial applications. So far, strategies to overcome these hinders include designing the composition and microstructure of silicon active materials to suppress the volume change and improve the conductivity, developing new binders and electrolyte additives and exploring new current collectors and suitable electrode structures. There are mainly two methods to improve the silicon active materials. One is to decrease the scale of active Si domain to nanoscale, the other is to fabricate the composite structures. This paper summarizes the recent progress in silicon based composite materials, including Si-nonmetal composites and Si-metal composites, as well as some researches of our group, and discusses the technological bottlenecks and development trends.

Recent progress on the polyanion-type cathode materials for lithium ion batteries is reviewed. Emphasis is placed on the discussion of the relationships between structures and properties of the cathode materials, especially on the role of the polyanion and how to improve their low electronic conductivity.

The progress on additives of interphase films formed on anode/electrolyte and cathode/electrolyte interphases for lithium ion batteries is reviewed in this paper. On the basis of summarization of the mechanism of SEI film formation on anode surface, the performance of additives is reviewed and evaluated from two different SEI formation mechanisms, modification film mechanism and formation film mechanism, respectively. The drawback and challenge of SEI film formation additives are also illustrated. In addition, the mechanism and the progress of additives on cathode/electrolyte interphase are basically introduced. At the end of the paper, the application of theoretical calculation methods on interphase film is basically reviewed, and the application of theoretical calculation methods on the designation and optimization of new additives is also prospected.

Contents
1 Introduction
2 Progress of formation process and characterization of interphase films
2.1 SEI of anode/electrolyte
2.2 Additives of interphase film formation on cathode/electrolyte
3 The application of theoretical calculation method on interphase film
3.1 The application of theoretical calculation method on the mechanism of interphase film formation
3.2 The application of theoretical calculation method on the mechanism and designation of additives of interphase film formation
4 Conclusion and prospect

Electrode materials are important building blocks of lithium ion batteries. The capacity of the anode material is usually more than 300 mAh/g while that of the cathode is still around 150 mAh/g. The capacity of the cathode materials has become a bottleneck to the improvement of the electrochemical performances of lithium ion battery. Li-rich layer-structured Li_1+xA_1-xO₂ (A = Mn, Ni, Co, Ti, Zr, etc.) cathode materials caught the attention of the scientists in the past decade due to high reversible capacity (200 mAh/g or more). These materials can also be written as xLi₂MO₃·(1-x)LiM'O₂ (M = Mn, Ti, Zr; M' = Mn, Ni, Co; 0≤x≤1). In this review, we introduce the synthesis methods, structure and the charge-discharge mechanism of this type of materials. More attention will be paid to the improvement to their electrochemical properties by surface (coating) and bulk (doping) modification. At the end of this review, the problems and prospects of the research on these cathode materials are commented.

Contents
1 Introduction
2 Structure of Li-rich layer-structured cathode materials
3 Synthesis of Li-rich layer-structured cathode materials
4 Charge-discharge mechanism
5 Surface and structural modification
5.1 Surface modification
5.2 Acidic treatment
5.3 Fluorine doping
5.4 Pre-cycling treatment
6 Prospects

Polyanion-type materials are considered as one of the most promising cathode materials for power batteries due to the good safety, low cost and environmental benign of the materials. However, the commercial application of this kind of material is hindered by the poor rate capability and low-temperature performance caused by the low electronic and ionic conductivity of the materials. Recently, the electrochemical performances of the materials have been improved to a certain extend by coating the material particles with carbon or conductive polymer, doping the compounds with foreign metal ions, and preparing the nano-structured materials. And the commercial applications of LiFePO₄ in power batteries have been successfully achieved.In this paper, the recent progress on the polyanion-type cathode materials, including silicates and sulfates which have become the research focus again, are reviewed. The crystal structure, synthesis and modification process, electrochemical characteristics, safety of the material, as well as the technical bottlenecks in the actual applications are discussed. The possible approaches to improve the output performance of the materials and the development trends of the polyanion-type cathode materials are also discussed and prospected. Contents 1 Introduction
2 Crystal structure, preparation, and electrochemical characteristic of polyanion-type cathode materials
2.1 Phosphates
2.2 Silicates
2.3 Sulfates
3 Strategies to improve the electrochemical performance of polyanion-type cathode materials
4 Safety of polyanion-type cathode materials
5 Complex/blend cathode materials
6 Conclusion and prospects

Layered mixed cobalt/nickel/manganese oxides as positive electrode materials for Li-ion batteries are of great interest due to their desirable properties. The development of layered lithium mixed cobalt/nickel/manganese oxides cathodes for rechargeable lithium batteries is reviewed. The inter-relationship between the structure and the electrochemical properties of LiCo1/3Ni1/3Mn1/3O2 is introduced in detail. The influences of synthesis method and doping elements on the performances of the materials are also discussed. Finally, the perspectives of the layered LiCo1/3Ni1/3Mn1/3O2 are analyzed.

Silicon-based materials are promising anode materials for lithium-ion batteries (LIBs) due to their high-energy capacity. However, the commercialization of silicon-based materials as the anode of LIBs has been hindered by the huge volume change, poor cycle life and low initial coulombic efficiency during the charge/discharge process. This article reviews the change of both the crystal structure and the surface/interface of Si-based material during the intercalation/deintercalation of lithium, and the methods improving the electrochemical performance. In addition, the prospects of silicon-based materials as the anode of LIBs are also discussed.

Thin film lithium-ion batteries based on polymer electrolytes and solid-state inorganic electrolytes are introduced in this article.We mainly review the progress of the all-solid-state thin film lithium-ion batteries based on inorganic electrolytes, including the preparation methods and the properties of the cathode materials,anode materials and solid-state inorganic electrolytes.The studies on constructions of the thin film lithium batteries are also presented.

Research progress and prospects of electrolytes used at elevated-temperature for lithium-ion batteries are summarized in this paper. The deficiency of current commercial electrolytes at high temperature is clarified according to the chemical stability of solutes and solvents. Some ideas are proposed to develop the thermal stability of lithium salts, ionic liquids and flame retardant additives. The deficiencies of the present lithium salts can be overcome through the modification of functional group or the structure composite, and new kind of lithium salt can be developed for elevated-temperature lithium ion battery. Non-carbonic acid ester showed poor performance when it was used alone, ionic liquids showed poor compatibility with commonly used anode and cathode materials. The most possible way for the application of high-temperature electrolyte is the blend of carbonates and flame retardants. Better flame retardant can be achieved by introducing flame-retardant elements into phosphate ester or modifying part of the functional group, which will improve the performance of electrolyte in high temperature. Contents
1 Introduction
2 High thermal stability electrolyte salts
2.1 Boron-based lithium salts
2.2 Lithium imides
3 Non-flammable solvents
3.1 Non-flammable organic solvents
3.2 Room temperature ionic liquids
3.3 Flame retardant additives
4 Conclusion and outlook

As a kind of promising anode material for lithium ion batteries, silicon-based materials have been attracted much attention. The poor cycling stability due to the huge volume change during lithiation and delithiation and the low initial coulombic efficiency are the critical problems that limit their commercial application. Nanocrystallization, alloying and carbon-coating are effective measures to solve these issues. This article reviews the progress in silicon/compound composites in which TiB2, TiN and TiC act as the matrices, silicon-metal composites including Fe-Si, Cu-Si and Ni-Si, and silicon/carbon composites. In respect of the research on silicon/carbon composites, emphasis is put on the preparation methods like pyrolysis, milling, milling-pyrolysis and chemical polymerization, and the carbon sources such as polypyrrole, polyvinylchloride(PVC), polyacrylonitrile(PAN), resorcinol-formaldehyde resin, citric acid and epoxy resin. In addition, the progress in Si/carbon nanotubes composite materials is also discussed.

Contents
1 Introduction
2 Si-compound composites
3 Si-metal composites
3.1 Si-Fe composites
3.2 Si-Cu composites
3.3 Si-Ni composites
4 Si/C composites
4.1 Si/C composites prepared by pyrolysis
4.2 Si/C composites prepared by ball-milling
4.3 Si/C composites prepared by ball-milling and pyrolysis
4.4 Si/C composites prepared by other methods
4.5 Si/carbon nanotubes
5 Conclusions

The breakthrough of electrode materials dominates the developments of Li-ion batteries. It is the key technology for lithium ion batteries to resolve the problems for the present electrode materials and predict the novel ones, which can be realized by the first principle calculations. This paper introduces the principle and applications of first principle calculations in the cathode materials for Li-ion batteries, including average lithium intercalation voltage, intercalation/extraction mechanism, structure stabilization and the prediction of novel cathode. Moreover, the significances and the limitations of first principle calculations are also discussed for the design of electrode materials in Li-ion batteries.