镁离子掺杂锂离子电池硅酸锰锂正极材料_英文_
硅酸盐学报
· 1084 ·2011年
镁离子掺杂锂离子电池硅酸锰锂正极材料
赵宏滨1,2，吴晓燕1，李永1，沈嘉年2，徐甲强1
(1. 上海大学理学院化学系，上海200444；2. 上海大学材料科学与工程学院，上海 200444)
摘要：以MgAC2为掺杂剂，葡萄糖碳化为碳包覆源，通过溶胶凝胶法制备了含有镁离子的硅酸锰锂正极材料前驱体，在惰性气保护下经高温焙烧得到碳包覆的硅酸锰锂正极材料。对镁离子掺杂对硅酸锰锂物理和电化学性能的影响进行了探讨。交流阻抗和循环伏安测试表明，碳包覆和低含量镁离子掺杂不会破坏硅酸锰锂的材料，并且显著提高了电子传导过程的电导率，同时硅酸锰锂正极材料的循环性能得到提高。0.1C倍率放电测试显示，镁离子掺杂和非掺杂的硅酸锰锂的不可逆比容量分别有289mA·h/g和248mA·h/g。经过20次循环，其容量分别保持在155mA·h/g和122mA·h/g。与未掺杂的硅酸锰锂相比，镁离子掺杂后，硅酸锰锂的循环稳定性得到极大的提高。
关键词：硅酸锰锂；镁离子掺杂；锂离子电池；碳包覆; 溶胶凝胶法
中图分类号：TQ171 文献标志码：A 文章编号：0454–5648(2011)07–1084–06
Effect of Mg2+ Doping on Structure and Electrochemical Performance of Lithium
Magnesium Silicate
ZHAO Hongbin1,2，WU Xiaoyan1，LI Yong1，SHEN Jianian1，XU Jiaqiang1,2
(1. College of Science, Shanghai University, Shanghai 200444; 2. School of Materials Science and Engineering,
Shanghai University, Shanghai 200444; China)
Abstract: Stoichiometric Mg-doped Li2MnSiO4 cathode material was synthesized by a sol–gels process with magnesium acetate de-hydrate as a dopant and sucrose as carbon-coating materials and subsequent high temperature treatment in an inert atmosphere. The effect of Mg2+ doping on the physical and electrochemical properties of the as-prepared cathode materials was investigated. AC im-pedance spectra and cycle voltammagram results showed that the carbon coating and low concentration Mg2+ doping do not destroy the structure of Li2MnSiO4, but enhance the electron conductivity during the electron translation procedure. Moreover, the cycle per-formance was improved. At a discharging rate of 0.1C, the reversible specific capacities of the Mg-doped lithium magnesium silicate and the un-doped Li2MnSiO4 were 289 and 248mA·h/g, respectively. After 20 cycles, the capacities were 155 and 122mA·h/g, re-spectively. By Mg ions doping, Li2MnSiO4 exhibited a more stable cycle performance than that of Li2MnSiO4/C cathode material.
Key words: lithium magnesium silicate; Mg-doped; lithium battery; carbon-coated; sol–gel
During the past decade, lithium batteries have been used as power sources for portable electronic devices and electric and hybrid vehicle for their advantages over other types of rechargeable batteries. Some lithium-rich mate-rials with tetrahedrally coordinated ions, such as AO4n–polyanions (for A=V, Si, Ge and P), have been investi-gated as cathode materials for lithium ion batteries due to their theoretical high charge/discharge capacity, redox volt-age, low cost and environmental friendly.[1] Padhi et al.[2–3] reported that a possibility of changing the ion-covalent character of the M–O bonding through inductive effect by selecting different X element, so as to establish a sys-tematic mapping and tuning of transition-metal redox potentials. An example for this cathode material is Li2MSiO4 (for M=Fe, Mn, Co, Ni), which has a theo-retical capacity of 330mA·h/g, as a potential prospective cathode [4–8].Nytén et al.[5–6] calculated the electro-che-mical performance of Li2FeSiO4 as a novel Li-battery material. Yang et al.[9] reported Li2MnSiO4 material syn-thesized by sol–gel method with TEOS as a silicon re-source. In their work, two lithium ions were deinterca-lated. Dominko[10] mentioned that Li2MnSiO4 should
收稿日期：2011–01–05。修改稿收到日期：2011–03–20。第一作者：赵宏滨(1974—)，男，博士。
通信作者：徐甲强(1963—)，男，教授。Received date:2011–01–05. Approved date: 2011–03–20. First author: ZHAO Hongbin (1974–), male, Ph.D.
E-mail: hongbinzhao@https://www.wendangku.net/doc/0114957299.html,
Correspondent author: XU Jiaqiang (1963–), male, professor. E-mail: xujiaqiang@https://www.wendangku.net/doc/0114957299.html,
第39卷第7期2011年7月
硅酸盐学报
JOURNAL OF THE CHINESE CERAMIC SOCIETY
Vol. 39，No. 7
J u l y，2011
赵宏滨等：镁离子掺杂锂离子电池硅酸锰锂正极材料· 1085 ·第39卷第7期
have a good lithium conductivity, and a poor electron conductivity would cause a poor electrochemical per-formance. The existing major problems are the low con-ductivity and poor electrochemical stability of Li2MnSiO4 cathode, which restrict the application.
To solve the problems above, some approaches are carbon coating to enhance electron conductivity, effective synthesis route to obtain structural stabled electrode ma-terials, and secondary metal doping to prevent the struc-ture subsidence as well. Usually, Li2MnSiO4 without any modification has a rather low conductivity. To enhance the conductivity, carbon coating[11] is considered as an effective method and used in the design of Li-ion battery material. Sucrose carbonization was reported by in-situ carbon coating. Yang et al.[9] reported the in-situ carbon coating method to improve the electron conductivity of Li2MnSiO4. Nuli et al.[12] used a molten salt method to synthesize MgMnSiO4 with a superior electrochemical stability.[12]
Noted that though these methods improve their elec-trochemical properties, the self-defect of the structure in the process of charge/discharge is a major problem to be solved. Also, secondary metal modification is used for LiFePO4, LiCoO2 and LiTiO4, but there are a few of re-search work on secondary metal modification of Li2MnSiO4. Therefore, it is necessary to investigate the electro-chemical properties of Li2MnSiO4 by secondary metal modification.
In this work, a novel Mg-doped Li2MnSiO4 electrode material was synthesized by a sol–gels method and a subsequent high temperature treatment process . Mg ions were introduced into the Li2MnSiO4 lattice to improve the structure stability and in-situ sucrose carbonization on the surface of Li2MnSiO4 particles to enhance the elec-trochemical conductivity.
1 Experimental procedure
1.1 Preparation of samples
The pure Li2MnSiO4 was synthesized by a sol–gels process. Lithium acetate dihydrate (Sinopharm Chemical Reagent Co. Ltd., China), manganese (II) acetate tetra-hydrate and sucrose (Sinopharm Chemical Reagent Co. Ltd., China) were dissolved in ethanol of 50mL under stirring. Then stoichiometric tetraethyl orthosilicate (TEOS) (Sinopharm Chemical Reagent Co. Ltd., China) was slowly dropped into the ethanol solution. Hydrochlo-ric acid of 0.01mol/L was dropped into the solution to adjust the pH value to 2.5–3.5. The obtained solution was heated in an oil bath at 80℃under stirring for 24h to form the sol. The sol was dried in a blast oven at 60℃for 24h to remove ethanol solvent and water. After grinding in a mortar and pestle, the obtained xerogels were heat-treated in an inert atmosphere (Ar) at 700℃for 5h. The resultant powder was Li2MnSiO4 coated by carbon black, which was used for the compositional, structural, and electrochemical characterization.
Carbon coated Li2MnSiO4 and Mg2+-doped Li2MnSiO4 were prepared by the same procedure for their compari-son. Stoichiometric magnesium (II) acetate (Sinopharm Chemical Reagent Co. Ltd., China), lithium acetate de-hydrate, manganese (II) acetate tetrahydrate and sucrose were used. Sucrose hyrolysis carbon content was 20% in mass fraction in the synthesized Li2MnSiO4 and Mg2+- doped Li2MnSiO4.
1.2 Electrochemistry measurement
The electrochemical performance was evaluated with coin cells assembled in standard 2016 cell hardware. Lithium metal was used as an anode. 1mol/L solution of LiPF6 in EC: DEC (1:1 in volume ratio) was used as an electrolyte, and celgard polypropylene was used as a separator. The cathode was prepared by blade-coating a slurry of 85% (in mass fraction, the same below) active material with conductive carbon black of 10% and a PTFE binder of 5% in NMP on an aluminum foil. This material was dried overnight at 120℃in a vacuum oven. The dried coated material was pressed and punched in the circular discs with the area of 1.1cm2 that typically had an active material weight of 5mg. The coin cell assembly was performed in an argon-?lled glove box with oxygen and moisture of <2%. The cells were cycled at a rate of 0.1C in the range of 1.5V and 4.8V(vs Li/Li+)in a multi-channel battery tester (LAND CT2001A). The slow scan cyclic voltammetric (SSCV) experiments were car-ried out on an Autolab PGSTAT302 electrochemical test system (Eco Chemie, the Netherlands) at a scan rate of 0.1mV/s in the range of 1.5 and 4.8V. The impedance spectra were recorded with 2016-type coin cells on Autolab PGSTAT302 set-up in the range of 60kHz and 0.001Hz. The cells were galvanostatically charged and discharged to various depths of intercalation and deinter-calation prior to the record of the impedance plots. All electrochemical tests were performed at room tempera-ture.
1.3 X-ray diffraction analysis
X-ray powder diffraction pattern of Li2MnSiO4 was determined by a Simens D-5000 diffractometer in a re?ection (Bragg–Brentano) mode with Cu Kα radiation (λ=0.15406nm). The data were collected in the range of 20°and 80°at an increased rate of 6°/min.
2 Results and discussion
Figure 1 shows the XRD patterns for the prepared Li2MnSiO4/C and Mg-doped Li2MnSiO4/C composites. Compared to the typical Li2MgSiO4 diffraction peaks (JCPDS#24-0636), these as-prepared materials have the same diffraction peaks at 2θ value of 32°, 36.5°, 57°, 59.5°, respectively. This illustrates that Li2MgSiO4 has the similar crystal structure as the pure Li2MnSiO4. The
硅酸盐学报
· 1086 ·2011年
Fig.1 XRD patterns for the prepared Li2MnSiO4/C and Li2Mg0.1?Mn0.9SiO4/C powders
diameter of magnesium is 0.066nm, which is a bit shorter than that of manganese (0.067nm). When Mg2+ replaced a fraction of Mn2+, the gaps of Li2MnSiO4 space group amplified and Li-ion was easy to intercalate and deintercalate from the crystals, resulting in the improve-ment of the conductivity of material. There existed little diffraction peak corresponding to Li4SiO4 and Li2SiO3 crystals,[13] showing that only Li2MSiO4 (M=Mg or Mn) phase existed in the composite. According to the Scherer equation, Li2MnSiO4/C and Mg-doped Li2MnSiO4/C with the averaged grain size of 20nm were obtained by the lattice space at 2θ value of about 33°, which could not be affected by other diffraction peaks.
Since the bond strength of Mg—O was larger than that of Mn—O, the bond strength of Li—O would decrease and Li-ion was easy to intercalate and deintercalate, thus leading to the improvement of the cyclic stability. When Mg2+ doped into the composite, there were two sites that Mg element could replace the M (Li) site or M (Mn) site. To maintain the charge balance, the cationic defects formed in this compound, namely, Li2–x–z Mg x MnSiO4 (M (Li)) or Li2–x Mg x Mn1–z SiO4 (M (Mn)) (where z is the cationic defect concentration). The M(Li) site defect formed at a high temperature, and Li ions decreased in the form of Li2O and more Mg2+ occupied on the M(Li) site. The M (Mn) site defect was due to that a fraction of Mn2+ was replaced by Mg2+, forming an impurity phase. However, there were little MnO phase diffraction peaks in the XRD patterns, which reflected that the more Mg2+ ions could occupy Li+ sites rather than Mn2+, and the more Li2+ ions were easy to diffuse in the crystal lattice, which could improve the conductivity. For a balance, two different Mg-doped phases could co-exist in the synthe-sized composite.
Figure 2(a) shows that the homogenous and well-dis- persed Li2MnSiO4 with the average particle size of 80nm
was obtained by carbon coating. The primary particles Fig.2 SEM images of different mass fraction of Mg-doped in Li2MnSiO4 /C composites
赵宏滨等：镁离子掺杂锂离子电池硅酸锰锂正极材料· 1087 ·第39卷第7期
aggregated, and the meso-nano sized scale of synthesized samples had a high specific surface for the electrochemi-cal reaction and a more stable structure in the charge/ discharge procedure. Mg-doped Li2MnSiO4 composites (Figs.2(b)–(c)) had the similar particle size distributions, illustrating that Mg2+ ions could be doped readily into the crystal lattice of Li2MnSiO4 in a sol–gels method and Mg2+ doping did not affect the average particle size.
Figure 3 shows the first 20-cycle charge/ discharge curves of Li2MnSiO4, Li2MnSiO4/C and Li2Mg0.1Mn0.9?SiO4/C. The first charge curve of Li2Mg0.1Mn0.9SiO4/C and Li2MnSiO4 had a potential descent and one strange platform occurred at 3.9V, corresponding to that of a mixed electrochemical reaction. In the case of discharge curves, only one platform at 3.4V was found, reflecting that Li intercalation was a mixed process. The pure Li2MnSiO4 without any carbon coating showed a poor cyclic performance after the first cycle. However, Li2MnSiO4 and Li2Mg0.1Mn0.9SiO4/C with carbon coating both showed an improved performance, in which carbon coating could affect the performance of battery. Therefore, a low conductivity of pure Li2MnSiO4 is one important defect that restricts the application.
Figure 4 shows the plot of discharge specific capacity versus cycle number. The initial charge specific capacity for Li2Mg0.1Mn0.9SiO4/C and Li2MnSiO4/C was 303 mA·h/g and 275mA·h/g, respectively, which was equal to 1.84 and 1.67 Li ion deintercalation. The discharge ca-pacity of Li2MnSiO4/C and Li2Mg0.1Mn0.9SiO4/C was 248 and 289mA·h/g,, giving that the Li+ intercalation number was 1.75 and 1.50, respectively. The electrochemical ac-tivity of the material was gradually activated in the initial cycles. In the five circles charge/discharge procedure, the charge and discharge capacity descended. After 20 cycles, the discharge capacity of Li2Mg0.1Mn0.9SiO4/C and Li2MnSiO4/C was 155 and 122mA·h/g, respectively. The improved cyclic performance should due to Mg-doped in the lattice of Li2MnSiO4/C, which could keep the struc-ture more stable in the process of charge/ discharge.
The AC impedance was used to investigate the effect of carbon coating and Mg-doped on the electron conduc-tivity of Li2MnSiO4/C (see Fig.6). The AC impedance spectrum showed a semicircle at a high frequency related to the surface membrane, and a semicircle at low fre-quency contributed to the surface resistance due to the active electron transfer resistance on the electrode inter-face in the presence of SEI layer. Clearly, the R ct of Mg-doped Li2MnSiO4/C was 350?, which was lower than that of undoped Li2MnSiO4/C(670?) and pure Li2MnSiO4 (1200?) (see Fig.6) when carbon coating and Mg-doping were applied to modify Li2MnSiO4, thus enhancing the charge/ discharge performance of Li2MnSiO4 composite.
The mechanism of lithium intercalation/ deintercala-
tion was discussed according to the electrochemical mea-
Fig.3 Charge/discharge curves of different cathode materials in the first 20 cycles (0.1C, 1.5–4.8V)
surement. Figure 7 shows that there are at least two pairs of oxidation/reduction peaks exist in the process of charge and discharge, which correspond to Mn2+/Mn3+ and Mn3+/Mn4+ redox couples, respectively. In the case of the forward scan, Mn valence was changed from +2 to +4 step by step, companying with the two-step lithium dein-tercalation. However, in the case of the backward scan, the discharge mechanism appeared complicated. A com-plex valence existed due to the unobvious plateau or re-duction peaks, which represented a mixed reaction among Mn2+, Mn3+ and Mn4+ redox couples.
硅酸盐学报
· 1088 ·2011年
Fig.4 Cyclic performance of Li2MnSiO4/C and Li2Mg0.1Mn0.9?SiO4/C (0.1C, 1.5–4.8V)
Fig.5 Equivalent circuit (Viogt-FMG model) used to fit the experimental AC impedance data
W1 is the diffusion element, R1, R4 are the serial and surface re-
sistance, respectively, C1 is the double layer pseudo capacity.
Before charge, the first cycle of the initial battery in-dicated that the active materials on the cathode and anode were unstable, and an activation procedure or a new phase transition occurred. According to the Jahn-Teller effect theory,[14–17] the trivalent manganese (Mn3+) in the LiMn2O4 crystal lattice can cause the disproportionate reaction of 2Mn3+→Mn2++Mn4+, and the performance of battery descends when the battery operates at a high temperature or undergoes the charge/discharge procedure for many times. For the Li2MnSiO4 cathode material, the like-Jahn-Teller effect also occurred when dealing with
the stability of the assembled battery. In the initial charge
Fig.6 AC impedance spectra of Li2MnSiO4/C and Li2Mg x?Mn1–x SiO4/C
Fitting lines show calculated results from equivalent circuit.
Fig.7 Cycle voltammagram of pure and doped Li2MnSiO4/C and Li2Mg0.1Mn0.9SiO4/C electrode at a scan rate of 0.1
mV/s
procedure, the first Li+ ion was deintercalated from the Li2MnSiO4 lattice, Mn n+ in the LiMnSiO4 lattice should change the valence from bivalent to trivalent for the charge conservation. When the self-oxidation-reduction reaction in the formed the formed Mn3+ under acidic condition occurred, the battery voltage could not increase but decrease from 4.2V to a low voltage plateau (3.8V) and then maintained at 3.8V for several hours. The volt-age increased slowly to a high voltage plateau of 4.5V. For the initial discharge procedure, the discharge mecha-nism was rather complicated and little voltage plateau between 4V to 3V was observed. It was indicated that some complicated reactions occurred, which should re-late to the energy transfer and Mn valence change. In the second cycle, all of the charge/discharge voltage plateaus, which correspond to the two Li+ ions intercalation/dein-
赵宏滨等：镁离子掺杂锂离子电池硅酸锰锂正极材料· 1089 ·第39卷第7期
tercalation procedures, lost the clear boundary. However, they showed a continuous and mixed plateau between 4V to 3V. A conjecture for this disproportionate reaction was attributed to either the decomposition of LiPF6 to HF with residual water in the EC/DEC solvent or the high cell potential decomposed electrolyte to form HF, thus leading to the acceleration of the disproportionate reac-tion. For the Mg-doped Li2MnSiO4, the charge voltage was decreased slightly and the stability of electrochemi-cal performance could be improved. The improvement of stability was due to that Mg doping in the Li2MnSiO4 lattice, which could play a role of preventing the collapse of the Li2MnSiO4 structure.
3 Conclusions
Stoichiometric Mg-doped Li2MnSiO4 cathode material was synthesized by a sol–gels process in an inert atmos-phere with MgAC2 as a dopant and carbonized sucrose as a carbon-coating material. The effect of Mg2+ doping on the physical and electrochemical properties of as-prepared cathode materials were investigated. The XRD patterns showed that there were no other phases but Li2MSiO4 (M =Mg, Mn), and the particle size was approximately 20 nm. The AC impedance response and constant current charge/discharge cycling tests confirmed that a low con-centration of Mg2+ doping could not affect the structure of the material, but could improve the electron conductivity during the electron translation procedure and the kinetics in terms of capacity delivery and cycle performance. At a discharging rate of 0.1C, the reversible specific capacities of the 10% Mg-doped lithium magnesium silicate and the undoped Li2MnSiO4 were 289 and 248mA·h/g, respec-tively. After 20 cycles, the capacities were 155 and 122 mA·h/g, respectively. Mg-doped lithium magnesium sili-cate exhibited the more stable cycle performance. Acknowledge
This work was financially supported by Shanghai Postdoc-toral Science Foundation (10R21412900), China Postdoctoral Science Foundation (20100470677) and Leading Academic Discipline Project of Shanghai Municipal Education Commis-sion (No.J50102). We also thank the Analysis and Research Center of Shanghai University for sample characterization.
References:
[1] ARROYO-DE DOMPABLO M E, ARMAND M, TARASCON J M, et al.
On-demand design of polyoxianionic cathode materials based on electro negativity correlations: An exploration of the Li2MSiO4 system (M=Fe,
Mn, Co, Ni)[J] .Electrochem Commun, 2006, 8: 1292–1298.
[2] PADHI A K, NANJUNDASWAMY A K, MASQUELIER S, et al.
Phospho-olivine as positive-electrode materials for rechargeable lith-
ium batteries [J]. J Electrochem Soc,1997, 144(5): 1609–1613.
[3] PADHI A K, NANJUNDASWAMY K S, GOODENOUGH J B. Effect
of structure on the Fe3+/Fe2+ redox couple in iron phosphates [J]. J Electrochem Soc, 1997, 144(4): 1188–1194.
[4] ROBERT ARMSTRONG A, LYNESS C, MéNéTRIER M, et al.
Structural polymorphism in Li2COSiO4 intercalation electrodes: A combined diffraction and NMR study [J]. Chem Mater, 2010, 22(5): 1892–1900.
[5] NYTéN A, ABOUIMRANE A, ARMAND M, et al. Electrochemical
performance of Li2FeSiO4 as a new Li-battery cathode material [J].
Electrochem Commun, 2005, 7: 156–160.
[6] NYTéN A, KAMALI S, H?GGSTR?M L, et al. The lithium extrac-
tion/insertion mechanism in Li2FeSiO4 [J]. J Mater Chem, 2006, 16: 2266–2272.
[7] ZHONG G H, LI Y L, YAN P, et al. Structural, electronic and electro-
chemical properties of cathode materials Li2MSiO4 (M=Mn, Fe, and Co): density functional calculations [J]. J Phys Chem C, 2010, 114 (8): 3693–3700.
[8] BELHAROUAK I, ABOUIMRANE A, AMINE K. Structural and
electrochemical characterization of Li2MnSiO4 cathode material [J]. J Phys Chem C, 2009, 113(48): 20733–20737.
[9] YANG Y, LI Y, GONG Z. Synthesis and characterization of high ca-
pacity Silicate/C cathode materials for lithium ion batteries [A]. Inter-
national Meeting on Lithium Batteries [C]. Biarritz, France, 2006: Ab-
stract 210.
[10] DOMINKO R, BELE M, GABERSCEK M, et al. Structure and electro-
chemical performance of Li2MnSiO4 and Li2FeSiO4 as potential Li-battery cathode materials [J]. Electrochem Commun, 2006, 8: 217– 222.
[11] TARASCON J M, GUYOMARD D. The Li1+x Mn2O4/C rocking-chair
system: a review [J]. Electrochim Acta, 1993, 38: 1221–1229.
[12] NULI Y N, YANG J, LI Y, et al. Molten salt synthesis of MgMnSiO4
for rechargeable magnesium battery cathode [J]. ECS Meeting Ab-
stracts, 2008, 802: 450.
[13] CRUZ D, BULBULIAN S, LIMA E, et al. Kinetic analysis of the
thermal stability of lithium silicates (Li4SiO4 and Li2SiO3)[J]. J Solid State Chem, 2006, 179: 909–916.
[14] THACKERAY M M, JOHNSON P J, De PICCIOTTO L A, et al.
Electrochemical extraction of lithium from LiMn2O4 [J]. Mater Res Bull, 1984, 19: 179–185.
[15] SHIN-ICHI N, SHOGO H, RYOJI K, et al. Structure of Li2FeSiO4[J].
J Am Chem Soc, 2008, 130(40): 13212–13213.
[16] ELLIS B L, LEE K T, NAZAR L F. Positive Electrode Materials for
Li-Ion and Li-Batteries [J]. Chem Mater, 2010, 22(3): 691–714. [17] KUGANATHAN N, ISLAM M S. Li2MnSiO4 lithium battery material:
Atomic-scale study of defects, lithium mobility, and trivalent dopants [J]. Chem Mater, 2009, 21(21): 5196–5202.
各种锂离子电池正极材料分析
锂离子电池现使用的正极材料有如下几种： 1、钴酸锂 钴酸锂也是目前应用最为广泛的正极材料，钴产生3.9V(vs. Li)的电势平 台，对钴酸锂而言，对应于其理论容量，高达274mAh/g，实际容量可达155mAh/g，具有很高的能量密度。主要应用于便携电池领域：如手机，PDA；移动DVD； MP3/MP4、笔记本电脑。 1）结构缺陷 对钴酸锂（LixCoO2，0
年产20万套锰系锂离子电池项目可行性研究报告
年产20万套锰系锂离子电池项目可 行性研究报告 目录 第一章项目投资总论 (3) 1.1 项目投资背景 (3) 1.1.7 编制原则 (4) 1.1.8 编制依据 (5) 1.1.9 可行性研究的范围和内容 (6) 1.2 项目投资可行性研究结论 (6) 第二章项目背景和发展概况 (8) 2.1 项目提出的背景 (8) 2.2 项目建设必要性 (10) 2.3 项目建设的可行性 (11) 第三章项目市场分析与建设规模 (12) 3.1 市场调查 (12) 3.3 市场推销战略 (22) 3.4 产品方案和建设规模 (24) 3.5 产品销售收入预测 (24) 第四章项目建设条件与厂址选择 (25) 4.1 原料资源 (25) 4.2 建设地区的选择 (26) 4.3 建设条件 (28) 4.4基础设施 (33) 4.5厂址选择 (33) 第五章建设内容和规模及产品方案 (33) 5.1、确定方案的依据和原则 (33) 5.2项目工程主要建设内容 (34) 5.3二期工程产品方案 (38) 第六章项目工程技术方案 (39) 6.1 土建工程方案选择 (39) 6.2设备安装工程技术方案 (44)
6.3项目主要技术工序和工艺路线 (45) 6.4总图布臵方案 (54) 第七章环保、消防、劳动安全与卫生 (58) 7.1设计依据和规范 (58) 7.2环境保护和消防 (58) 7.3安全卫生 (60) 第八章项目节能措施 (61) 8.1编制依据 (61) 8.2节能方案设计采用的具体标准 (61) 第九章项目的组织管理和实施进度 (64) 9.1项目的组织管理 (64) 9.2项目工程的质量管理 (66) 9.3 项目建设管理机构 (67) 9.4 劳动定员与人员培训 (67) 9.5 项目实施进度安排 (68) 第十章投资估算与资金筹措 (69) 10.1投资估算 (69) 10.2资金来源 (72) 第十一章财务评价 (73) 11.1 编制依据 (73) 11.2 收入测算 (73) 11.3 销售税金及附加 (73) 11.4 销售成本 (74) 11.5 销售利润 (75) 11.6 财务评价静态指标 (75) 11.7 财务评价动态指标 (76) 11.8 财务评价结论 (77) 第十二章工程招标管理 (78) 12.1 编制依据 (78) 12.2 概述 (78) 12.3 发包方式 (78) 12.4 招标组织形式 (79) 12.5 招标方式 (80) 第十三章结论与建议 (82) 13.1推荐方案的总体描述 (82) 13.2 研究结论 (82) 13.3 建议 (83)
锂离子电池正极材料技术进展_孙玉城.
锂离子电池正极材料技术进展 孙玉城 1, 2 (1. 青岛科技大学新材料研究重点实验室 , 山东青岛 266042; 2. 青岛新正锂业有限公司 摘要 :概述了国内外近 30a 有关锂离子电池正极材料的研究进展以及笔者在锰系正极材料方面的研究结果 ; 比较了几种主要正极材料的性能优缺点 ; 阐明了正极材料发展方向。近期镍钴锰酸锂三元材料将逐步取代钴酸锂 , 而改性锰酸锂和镍钴锰酸锂三元材料以及两者的混合体将在动力型锂离子电池中获得广泛使用。在未来 5~10a , 高容量的层状富锂高锰型正极材料或许会是下一代锂离子电池正极材料的有力竞争者。 关键词 :锂离子电池 ; 正极材料 ; 技术进展 中图分类号 :TQ131.11文献标识码 :A 文章编号 :1006-4990(2012 04-0050-05 Technology development in cathode materials of lithium ion battery Sun Yucheng 1, 2 (1. Novel Material Research Focus Laboratory , Qingdao University of Science and Technology , Qingdao 266042, China ; 2. Qingdao LNCM Company Abstract :The technology development in the main cathode materials of lithium ion battery at home and abroad of the past 30 years and the author ′ s research results of Mn-based cathode materials were discussed respectively.Advantages and disadvan -tages of the main cathode materials and opinions of the development trend in the cathode materials of lithium ion battery were summarized.It was believed that Li (Mn , Co , Ni O 2is going to replace LiCoO 2and LiMn 2-x A x O 4or Li (Mn , Co , Ni O 2or the mixture
锂离子电池正极材料的几种体系
锂离子电池正极材料的几种体系 主要包括：锂钴氧化物、锂镍氧化物、锂锰氧化物和聚阴离子正极材料系列。 1. 锂钴氧化物 锂钴氧化物是现阶段商品化锂离子电池中应用最成功、最广泛的正极材料。其在可逆性、放电容量、充放电效率和电压稳定方面是比较好的。LiCoO2属于α-NaFeO2型结构，它具有二维层状结构，适合锂离子的脱嵌，其理论容量为274mAh/g，但在实际应用中，由于结构稳定性的限制，最多只能把晶格中的一半Li+脱出，因此实际比容量约为140mAh/g 左右，其平均工作电压高达3.7V。因其容易制备，具有电化学性能高，循环性能好、性能稳定和充放电性能优良等优点，成为最早大规模商业化应用于锂离子电池的正极材料，目前商品化锂离子电池70%以上仍然采用钴酸锂作为其正极材料。LiCoO2一般采用高温固相法制备，该种方法工艺简单、容易操作、适宜于工业化生产，但是也存在着以下缺点：反应物难以混合均匀，需要较高的反应温度和较长的反应时间，能耗大，产物颗粒较大，形貌不规则，均匀性差，并且难以控制，从而导致电化学性能重现性差。为了克服固相反应的缺点，溶胶-凝胶法、水热法、共沉淀法、模板法等方法被用来制备LiCoO2，这些方法的优点是可以使Li+和Co2+之间充分接触，基本达到原子水平的混合，容易控制产物的粒径和组成。但是这类制备方法工序比较繁琐，工艺流程复杂，成本高，不适用于工业化生产。 2. 锂镍氧化物 镍酸锂（LiNiO2）为立方岩盐结构，与LiCoO2相同，但其价格比LiCoO2低。LiNiO2理论容量为276mAh/g，实际比容量为140~180mAh/g，工作电压范围为2.5V~4.2V，无过充或过放电的限制，具有高温稳定性好，自放电率低，无污染，是继LiCoO2之后研究得较多的层状化合物。但LiNiO2作为锂离子电池正极材料存在以下问题亟待研究解决。首先，LiNiO2制备困难，要求在富氧气氛下合成，工艺条件控制要求较高且易生成非计量化合物。LiNiO2合成技术的关键是将低价的镍完全转变为高价镍，高温虽然可以实现LiNiO2的高效合成，但由于温度超过600℃时合成过程中的Ni2O3易分解成NiO2，不利于LiNiO2的形成，所以必须选用苛刻的低温合成方法。此外，在制备三方晶系的LiNiO2过程中，容易生成立方晶系的LiNiO2，由于立方晶系的LiNiO2在非水电解质溶液中无活性，因此，工艺条件控制不当，极易导致LiNiO2材料的电化学性能不稳定或下降。其次，LiNiO2与LixCoO2一样，在充放电过程中，也会发生从三方晶系到单斜晶系的转变，导致容量衰减[69]，与此同时，相变过程中排放的O2可能与电解液反应，此外，LiNiO2在高脱锂状态下的热稳定性也较差，，易于引发安全性问题。可喜的是，通过掺入少量Cu、Mg、Al、Ti、Co等金属元素，可使LiNiO2获得较高的放电平台和电化学循环稳定性。 3. 锂锰氧化物 我国锰资源储量丰富，而且锰无毒，污染小，因此层状结构的LiMnO2和尖晶石型的LiMn2O4都成为了正极材料研究的热点。锂锰氧化物主要有层状LiMnO2和尖晶石型LiMn2O4两类。LiMnO2属于正交晶系，岩盐结构，氧原子分布为扭变四方密堆结构，其空间点群为Pmnm，理论比容量达到286mAh/g，充放电范围为2.5~4.3V，是一种较
锂离子电池三元镍钴锰正极材料研究现状综述
三元系锂电池正极材料研究现状 摘要：综述了近年来锂离子电池层状Li-Ni-Co-Mn-O正极材料的研究进展，重点介绍了正极材料LiNi l/3Co l/3Mn l/3O其合成方法电化学性能以及掺杂、包覆改性等方面的研究结果。 三元系正极材料的结果： LiMn x Co y Ni1-x-y O2具有α-2NaFeO2层状结构。Li原子占据3a位置,Ni、Mn、Co随机占据3b位置,氧原子占据6c位置。其过渡金属层由Ni、Mn、Co 组成,每个过渡金属原子由 6 个氧原子包围形成MO6 八面体结构,而锂离子嵌入过渡金属原子与氧形成的(MnxCo yNi1-x-y) O2层之间。在层状锂离子电池正极材料中均有Li+与过渡金属离子发生位错的趋势,特别是以结构组成中有Ni2+存在时这种位错更为突出。抑制或消除过渡金属离子在锂层中的位错现象是制备理想α-2NaFeO2结构层状正极材料的关键，在LiMn x Co y Ni1-x-y O2结构中, Ni2+的半径( rNi2+=0.069nm)与Li+的( rLi+=0.076nm)半径接近,因此晶体结构会发生位错,即过渡金属层中的镍原子占据锂原3a的位置,锂原子则进驻3b位置。在Li+层中,Ni2+的浓度越大,则Li+在层状结构中脱嵌越困难,电化学性能越差。而相对于LiNiO2及LiNi x Co1-x-y O2 ,LiMn x Co y Ni1-x-y O2中这种位错由于Ni 含量的降低而显著减少。同时由于Ni2 + 的半径( rNi2 + =0. 069nm) 大于Co3+ ( rCo3+ = 0. 0545nm) 和Mn4 + ( rMn4 + =0. 053nm) ,LiMnxCo yNi1 - x - yO2 的晶格常数有所增加。 由于充分综合镍酸锂的高比容量、钴酸锂良好的循环性能和锰酸
锂电池各个体系性能参数
钴酸锂 1.钴酸锂的概述 1992年SONY公司商品化锂电池问世，由于其具有工作电压高、能流密度高、循环压寿命长、自放电低、无污染、安全性能好等独特的优势，现已广泛用作移动电话、便携式计算机、摄像机、照相机等的电源。并已在航天、航海、人造卫星、小型医疗仪及军用通讯设备中逐步发展成为主流应用的能源电池。Sony公司推出的第一块锂电池中，正极材料是钴酸锂，负极材料为碳。其中，决定电池的可充电最大容量及开路电压的主要是正极材料。因此我国现有的生产正极材料公司，产品几乎全部是钴酸锂。与钴酸锂同属4伏正极材料的候选体系有镍酸锂和锰酸锂两大系列，这两个系列材料在性能上各有长短，锰酸锂在原料价格上优势明显。但在容量和循环寿命上存在不足。钴酸锂的实际使用比容量为130mAh／g，循环次数可达到300至500次以上：而锰酸锂的实际比容量在100mAh ／g左右，循环次数为100至200次。另外，磷酸铁锂电池有安全性高。稳定性好、环保和价格便宜优势，但是导电性较差，而且振实密度较低。因此其在小型电池应用上没有优势。国内钴酸锂市场需求变化呈现典型的中国市场特征，历史较短，但发展较快，多数企业在很短时间进入，但生产企业规模不大，产品主要集中在中低档。 2002年，国内钴酸锂材料市场需求量为2400吨，大多数产品依靠进口，但随着国内主要生产企业的投产，产能和需求量得到了极大的提升，2006年需求量达到6500吨，2008年需求量接近9000吨。 2001年全球主要生产高性能钴酸锂、氧化钴材料的生产企业是比利时Umicore 公司，美国OMG和FMC公司,日本的SEIMEI和日本化学公司等国外企业。另外台湾地区的台湾锂科科技公司也是重要的生产企业。而国内的生产企业为北京当升科技、湖南瑞翔、中信国安盟固利、北大先行和西安荣华等。这些生产企业有些是从科研机构孵化而来，有些是具有上有资源优势的企业。 2.钴酸锂的材料构成 LiCoO2在目前商业化的锂离子电池中基本上选用层状结构的锂离子二次电池正极材料（钴酸锂）的液相合成工艺，它采用聚乙烯醇（ＰＶＡ）或聚乙二醇（ＰＥＧ）水溶液为溶剂，锂盐、钴盐分别溶解在ＰＶＡ或ＰＥＧ水溶液中，混合后的溶液经过加热，浓缩形成凝胶，生成的凝胶体再进行加热分解，然后在高温下煅烧，将烧成的粉体碾磨、过筛即得到钴酸锂粉。与现有技术相比，本发明具有合成温度低，得到的产品纯度高、化学组成均匀等优点。 3.钴酸锂的制备 1活性钴酸锂的制备方法，其特征是包括以下步骤：以原生钴矿石为原料，制取高纯钴盐溶
锂离子电池三元正极材料的分析研究进展
锂离子电池三元正极材料的研究进展 2009年09月01日作者：丁楚雄／孟秋实／陈春华来源：《化学与物理电源系统》编辑：樊晓琳 摘要：本文综述了锂离子电池正极材料层状三元过渡金属氧化物Li-Ni-Co-Mn-O的研究进展，讨论了三元材料的结构特性与电化学反应特征，重点介绍了三元材料的制备方法和掺杂、表面修饰等改性手段，并分析了三元材料目前存在的问题和未来的研究重点。 关键词：锂离子电池；Li-Ni-Co-Mn-O；层状结构；制备方法；改性 Abstract: The research progress of the ternary transition metal oxides LiNi1-x-yCoxMnyO2 as layered cathode materials for lithium ion batteries is reviewed. The structure and electrochemical performances of the materials are discussed. Various synthesis methods, doping and surface-modification approaches are introduced in detail. Finally, the current main problems and further research trend of the materials are pointed out. Key words: lithium ion battery。 cathode。 layered structure。 synthesis methods。modification 1、引言 锂离子电池因其电压高、能量密度高、循环寿命长、环境污染小等优点倍受青睐[1, 2]，但随着电子信息技术的快速发展，对锂离子电池的性能也提出了更高的要求。正极材料作为目前锂离子电池中最关键的材料，它的发展也最值得关注。 目前常见的锂离子电池正极材料主要有层状结构的钴酸锂、镍酸锂，尖晶石结构的锰酸锂和橄榄石结构的磷酸铁锂。其中，钴酸锂 锂离子电池正极材料镍钴锰酸锂的研究进展 杨杰10070134 摘要：对镍钴锰酸锂的制备方法(如高温固相合成法、溶胶一凝胶法、共沉淀法)进行了重点论述，并讨论了相应的电化学性能、结构特征和目前存在的问题。并对层状镍钴锰酸锂正极材料的发展进行了展望。关键词：锂离子电池；正极材料；理论容量；层状镍钴锰酸锂Progress in Research of Layered LiNi1/3 Co1/3 Mn1/3 O2 Cathode Material fjDr Lithium—ion Batteries Abstract：The preparation methods of layered LiNi1/3Co1/3Mn1/3 O2 calhode， such as high一tempemture solidrection method，sol-gel method，co—precipitation metllod and etc，was reviewed in this paper．The related electmchemical properties，stmcturecharacteristics and existing problems were discussed as well．The development of the layered“Ni1/3 Co1/3 Mn1/3 O2 cathode material was forecasted． Key words：lithium-ion battery；cathode material；theoretical capacity； layeredNi1/3 Co1/3 Mn1/3 O2 层状LiNi1/3Co1/3Mn1/3O2作为一种新型的锂离子电池正极材料，其理论容量高达278 mAh/g。LiNi1/3Co1/3Mn1/3O2具有a-NaFeO2型层状结构，Ni为+2价，co为+3价，Mn为+4价，少量的Ni3+和Mn3+。充电时，Mn4+不变价，Ni2+变为Ni4+，C03+变为c04+。LiNi1/3Co1/3Mn1/3O2集中了LiCoO2,LiNiO2,LiMnO2三种材料各自的优点，成本比LiNi0.8Co0.2O2稍低，电性能比LiNi1/2Mn1/2O2好。 由于存在三元协同效应，其综合性能优于任何一单组合化合物。本文着重对最近层状LiNi1/3Co1/3Mn1/3O2的制备方法以及电化学性能进行了综述。 毕业设计（论文） 题目锂离子电池正极材料尖晶石 锰酸锂的制备及性能研究 系（院）化学与化工系 专业应用化工技术 班级 学生姓名 学号 指导教师 职称讲师 二〇年月日 锂离子电池正极材料尖晶石锰酸锂的制备及性能研究 摘要 锂离子电池因其优越的电化学性能、高比容量、长循环寿命、高能量密度以及放电电压高、体积小、环保绿色等特性在过去的十年内得到了迅猛发展。作为锂离子电池重要组成部分的正极材料也成为当前该领域研究的热点之一。尖晶石型LiMn2O4以其高能量密度、价格低廉、无环境污染等特点而被视为最具发展潜力的锂离子电池的正极材料之一。对高温反应而言，包括高温固相反应法、熔融浸渍法、微波烧结法及其他改进的方法；在低温反应方法中，主要讨论了溶胶凝胶法、共沉淀法及乳化干燥法等。体相掺杂和表面修饰是抑制尖晶石型LiMn2O4容量衰减的有效方法。从锰酸锂的制备与改性研究方面综述了锂离子电池正极材料锰酸锂的研究进展，在此基础上提出了正极材料锰酸锂的发展方向。 关键词: 锂离子电池；正极材料；锰酸锂 Preparation and modification of LiMn2O4 as cathode material for lithium ion batteries Abstract Lithium-ion batteries have developed greatly because of its excellent electrochemical properties, high specific capacity, long cycle performance, high energy density and other merits, such as high discharge voltage, small volume and less harm to environment. Spinal LiMn2O4 is a potential cathode material of Li-ion batteries because of its high energy density, low cost and no pollution to environment, etc. Among the synthetic methods, conventional solid-state reaction method, melt-impregnation method, microwave sintering method an-dot her modified method are included in the high-temperature synthetic methods whereas the sol-gel method, co-precipitation method and micro-emulsion method are included in the low-temperature methods. Doping and surface modification are the effectively ways to restrain the capacity loss in cycling. Research progress in recent years on preparation and modification of lithium manganate cathode material was introduced, and based on that, the major developing trend was prospected. Key words: lithium ion battery；cathode material；LiMn2O4 * ? ( , , 200050) (2012 1 18 ;2012 3 7 ) LiMnO2 Li2MnO3 , . , . 5% 0.1V. , , , ; Li2MnO3 , .Li2MnO3 , , , . : , , ,Li2MnO3 PACS:31.15.es,62.20.de,82.45.Fk,82.47.Aa 1 , (>150W·h/kg) (<50W·h/kg), , [1?3]. Li M O2(M=Co, Ni,Mn ), Li M2O4(M=Mn,Ti ) Li M PO4(M=Fe,Mn,Co ), . , Li2MnO3 , x Li2MnO3·(1?x)Li M O2(M=Mn,Ni,Co ), [4?6]. , , . , ; , . , , [4?6]; , [7,8]; LiFePO4 [9]. , , [10]. , , [11]. , , , , , . LiMnO2 Li2MnO3 , * ( :50825205) . ?E-mail:jliu@https://www.wendangku.net/doc/0114957299.html, c 2012 Chinese Physical Society https://www.wendangku.net/doc/0114957299.html, , . 2 , 3 , 4 , Li2MnO3 . 2 2.1 LiMnO2 Li2MnO3 . x2 Li x2A, (x1?x2) Li x 2 A+(x1?x2)Li=Li x1A,(1) , [12?14] V=?E Li x1 A?E Li x2A?(x1?x2)E Li (x1?x2)F ,(2) F ,E Li x1A ,E Li L i x A . ,L i x2A , e i, (1) , L i x1A e j; , , . (<5%) (2) , (2) E Li x2 A E Li x1A E Li x 2A E Li x 1 A , . . , [15?17] E=E0+1 2 ?0 ∑ ij (C i j e i e j),(3) E0 ,C ij e i e j ,?0 . (2) (3) , : V=V0+1 2 ∑ ij (? 0C ij e i e j??0C ij e i e j),(4) V0 , ,?0 ? 0 x1 x2 . “ ” . ,(4) . , , ,e(x2)=e(x1+?x)≈e(x1). (4) V=V0+ 1 2 ∑ ij (? 0C ij??0C ij)e i e j.(5) , (5) .(5) , , (2) . , , 5%[11,14], , (5) , . LiMnO2 Li2MnO3 , ( 1(b)—(e)). , e e i,e j e k, V=V0+ 1 2 [? 0(C ii+2C ij+C jj+2C jk +C kk+2C ik)??0(C ii+2C ij+C jj +2C jk+C kk+2C ik)]e2.(6) , e e i e j, V=V0+ 1 2 [? 0(C ii+2C ij+C jj) ??0(C ii+2C ij+C jj)]e2;(7) e k (5) V=V0+ 1 2 (? 0C kk??0C kk)e2k.(8) (8) , , . , , , , . 各种锂离子电池正极材料分析 锂离子电池现使用的正极材料有如下几种： 1、钴酸锂 钴酸锂也是目前应用最为广泛的正极材料，钴产生3.9V(vs. Li)的电势平台，对钴酸锂而言，对应于其理论容量，高达274mAh/g，实际容量可达155mAh/g，具有很高的能量密度。主要应用于便携电池领域：如手机，PDA；移动DVD；MP3/MP4、笔记本电脑。 1）结构缺陷对钴酸锂（LixCoO2，0 锂离子电池几种有机正极材料介绍 随着储能电源和电动汽车的迅猛发展，开发高能量密度的锂离子电池成为研究的重点之一。锂离子电池性能的提高很大程度上取决于正极材料的特性。目前无机正极材料使用广泛，但不乏各种缺陷。与无机正极材料相比，有机物正极材料具有理论比容量高、原料丰富、环境友好、结构可设计性强和体系安全的优点，是一类具有广泛应用前景的储能物质。本文主要介绍了几类作为锂离子正极材料的有机化合物，对比分析了这些化合物的电化学性能、电化学反应机理。 导电有机高分子正极材料 早期的有机正极材料研究较多的是导电高分子材料，单一态的导电高分子正极材料存在许多缺陷，不能满足实际应用的需求，人们开始了基于导电高分子的各种复合材料的研究。研究人员将V2O5掺杂在聚吡咯中制备PPy/ V2O5复合材料，充放电后PPy/ V2O5复合材料发生阴离子的掺杂/脱掺杂以及Li+的嵌入/脱嵌入反应,正极材料内部元素的百分含量和材料内部的外观形貌会发生变化循环稳定性能不佳。 图1 PPy/ V2O5复合材料电化学性能及充放电后表面形貌图该类导电聚合物用作锂电池正极材料是通过阴离子的掺杂/脱掺杂实现电化学过程。通常存在以下缺点：反应体系中要求电解液的体积大，导致电池的能量密度难以提高，导电性能不高;电化学反应速度慢，需要掺杂大量的导电剂;有机聚合物在电解液中仍然存在缓慢溶解的问题;长期循环稳定性能不高;理论容量不高。存在很大的改进空间。 有机硫化物正极材料 科研人员又将目光转向了以S-S键的断裂和键合进行放能和储能的有机硫化物。他们发现增加硫链长度可以增加比容量，但是由于硫本身的绝缘性，且电极反应产生的中间产物Li2SX易于溶解在电解液和沉积在锂负极表面,严重影响了电池的充放电功率和循环性能。所以，他们又将S-S键引入有机物分子中，形成各种线形、梯形或者网状多交联的硫化聚合物，代表性的化合物如表1所示。 表1 典型有机硫化合物正极材料 有机硫化合物正极材料虽然在一定程度上提高了电池电化学活性和循环稳定性能，但有机硫化合物普遍存在以下问题：容量衰减快，易发生降解;在电解液中的溶解问题难以克服，循环稳定性能仍然不高;放电时生成的硫离子向负极转移的问题;导电性差，室温下电化学反应速度缓慢;有机硫化合物正极活性材料的循环性能离实际应用仍有差距，难以满足实际应用的需要。 含氧共轭有机物正极材料 有机共轭含氧化合物电极材料具有高比容量、结构多样性和反应动力学快等优点，已成为锂离子电池正极材料的研究热点。以蒽醌及其聚合物、含共轭结构的酸酐等为代表的羰基化合物作为一种新兴的正极材料逐渐受到关注，其电化学反应机制是：放电时每个羰基上的氧原子得一个电子，同时嵌入锂离子生成烯醇锂盐;充电时锂离子脱出，羰基还原，通过羰基和烯醇结构之间的转换实现锂离子可逆地嵌入和脱出。 科研人员研究了一种新型有机醌类化合物1,4,5,8-四羟基-9,10-蒽醌(THAQ，图2)及其氧化产物(O-THAQ)的电化学性能，其首次充放电容量和循环性能都较高。 锂离子电池电极材料综述 一、引言 从上世世纪70年代起锂离子电池的研究至第一个可充式锂-二硫化钼电池于1979年研究成功，再到1991年SONY公司首次推出商品化锂离子电池产品算起，锂离子电池的发展至今已有30多年的时间。锂离子电池是以Li+嵌入化合物为正负极的二次电池，实际上是一个锂离子浓差电池，正负极由两种不同的锂离子嵌入化合物组成。与其它蓄电池相比，锂离子电池具有开路电压高、循环寿命长、能量密度高、安全性能高、自放电率低、无记忆效应、对环境友好等优点。目前，锂离子电池已经被广泛应用于移动通讯、便携式笔记本电脑、摄像机、便携式仪器仪表等领域。随着这些电器的高能化，轻量化，对锂离子电池的需求也越来越迫切。同时被看作是未来电动汽车动力电源的重要候选者之一，并在空间技术、国防工业等大功率电源方面展示出广阔的应用前景 二、工作原理 锂离子电池通常正极采用锂化合物，负极采用锂－碳层间化合物。电介质为锂盐的有机电解液。充电时，Li+从正极脱嵌经过电解质嵌入负极，正极处于贫锂态，同时电子的补偿从外电路供给到碳负极，保证负极的电荷平衡。放电时， Li+从负极脱嵌经过电解质嵌入正极，正极处于富锂态。在正常充放电过程中， Li+在层状结构的碳材料和层状结构的金属氧化物的层间嵌入和脱出，一般只引起层面间距变化，不破坏晶体结构。 三、电极材料 （1）电极材料的性能要求 简单来说，电池主要包括正极、负极、电解质与隔膜四个部分。正极材料通常是一种嵌入化合物，在外电场作用下化合物中的锂可逆的嵌入和嵌出；负极材料一般是层状结构的碳材料。 锂离子电池正极材料在改善电池容量方而起着非常重要的作用。理想的正极材料应具备以下品质：点位高、比能量大、电池充放 锂离子电池正极材料研究进展 前言 由于提高负极材料对锂离子的嵌入和脱出能力是目前提高锂离子电池容量的主要途径，因此对负极材料尤其是碳材料的研究备受关注，相关的研究正如火如荼地进行着。但是，只有正极材料和负极材料相互匹配，才能使电池容量得到真正的提高，因此对于正极材料的研究也是方兴未艾。目前研究主要集中在锂钴氧化物，锂镍氧化物和锂锰氧化物。此外，纳米电极材料，共混电极及其他一些新材料电极也值得关注。 锂钴氧化物 作为锂离子电池正极材料的锂钴氧化物具有电压高，放电平稳，适合大电流放电，比能量高，循环性好的优点。其二维层状结构属于α-NaFeO2型，适合锂离子嵌入和脱出。其理论容量为274mAh／g，实际容量约为140mAh／g。由于其具有生产工艺简单和电化学性质稳定等优势，所以率先占领市场。其合成方法主要有高温固相合成法和低温固相合成法。 高温固相合成法以Li2CO3和CoCO3为原料，按Li/Co的摩尔比为1∶1配制，在700℃～900℃下，空气氛围中灼烧而成。也有采用复合成型反应生成LiCoO2前体［1］，在350℃～450℃下进行预热处理，再在空气中于700℃～850℃下加热。在合成之前的预处理工艺［2］能使晶体的生长更为完美，从而获得具有高结晶度层状结构的LiCoO2，提高了电池的循环寿命，其实际容量可达150mAh／g。 低温固相合成法是将混合好的Li2CO3和CoCO3在空气中匀速升温至400℃，保温数日，以生成单相产物。此法合成的LiCoO2具有较为理想的层状中间体和尖晶石型中 间体结构。 在反复的充放电过程中，由于锂离子的反复嵌入与脱出，使活性物质的结构在多次收缩和膨胀后发生改变，同时导致LiCoO2发生粒间松动而脱落，使内阻增大，容量减小。为提高LiCoO2的容量，改善其循环性能，可采取以下方法：①加入铝、铟、镍、锰、锡等元素，改善其稳定性，延长循环寿命。②通过引入磷、钒等杂原子以及一些非晶物［3］，使LiCoO2的晶体结构部分变化，提高电极结构变化的可逆性。③在电极材料中加入Ca2＋或H＋，提高电极导电性，有利于电极活性物利用率和快速充放电性能的提高。④通过引入过量的锂，增加电极的可逆容量。 锂镍氧化物 锂镍氧化物的理论容量为274mAh／g，实际容量已达190～210mAh／g。其自放电率低，没有环境污染，对电解液的要求较低。与LiCoO2相比，LiNiO2具有一定的优势。 ①从市场价格来看［4～5］，1995年至1997年，镍的LME现货平均价从8230美元／t 迅速降至6927美元/t。到本世纪末，世界镍产量还将增加30万吨。目前镍市场是供大于求。而国内的镍由于成本高和行业水平低，具有相当的发展潜力。反观钴的情况，虽然世界产量由1995年的2.14万吨升至1996年的2.58万吨，国内市场钴价仍由1996年每吨40.45～41.05万元升至1997年的每吨41～45万元。②从储量上来看，世界上已探明镍的可采储量约为钴的14.5倍。③从结构上看，LiNiO2与LiCoO2同属α-NaFeO2型结构，取代容易。 虽然在空气氛围中很难得到化学计量比的LiNiO2，但由于空气氛围在大规模生产条件下有着不可忽视的优势，因此尽管非氧条件下合成LiNiO2尚无大的突破，仍有不少科研工作者乐此不疲［6］。而在氧气氛围下采用Li2CO3和Ni(OH)2为原料合成的LiNiO2中含有杂质Li2Ni8O10，所以LiNiO2多用LiOH和Ni(OH)2为原料合成。因为［7］在锂离子电池正极材料镍钴锰酸锂的研究进展
锂离子电池及性能研究
系锂离子电池正极材料输出电压的影响
各种锂离子电池正极材料分析
锂离子电池几种有机正极材料介绍
锂离子电池电极材料综述(精)
锂离子电池正极材料研究进
- 各种锂离子电池正极材料分析
- 锂离子电池三元正极材料(全面)分解
- 各种锂离子电池正极材料分析
- 锂离子电池正极材料行业简析
- 锂离子电池正极材料结构原理详解
- 锂离子电池正极材料——三元材料
- 锂离子电池正极材料知识概述PPT(共 42张)
- 锂离子电池三元正极材料(全面)
- 锂离子电池正极材料
- 锂离子电池正极材料知识概述
- 锂离子电池三元正极材料的分析研究进展
- 锂离子电池几种有机正极材料介绍
- 锂离子电池正极材料概述 25页PPT文档
- 锂离子电池正极材料技术进展_孙玉城.
- 系锂离子电池正极材料输出电压的影响
- 锂离子电池正极材料研究进
- 锂离子电池正极材料的结构及性能资料
- 锂离子电池正极材料 ppt课件
- 常见锂离子电池正极材料及其性能
- !锂离子电池正极材料的晶体结构及优劣