高镍三元正极材料LiNi0.8Co0.1Mn0.1O2的合成与改性

LiNi_(0.8)Co_(0.1)Mn_(0.1)O_2是一种具有高能量密度的锂离子电池正极材料,但实际应用中的循环性能不佳、热稳定性差等缺陷亟待改善。本研究通过高温固相反应法制备了LiNi_(0.8)-Co_(0.1)Mn_(0.1)O_2材料,并采用H_3BO_3对其进行包覆改性。扫描电镜(SEM)显示包覆热处理后正极材料表面形成了一层不均匀絮状包覆物,X射线光电子能谱(XPS)测试显示该包覆物为LiBO_2和Li_2B_4O_7的混合物。电化学测试表明包覆物有效减缓了循环过程中的阻抗增加,显著提升了正极材料的容量与循环性能,其中0.5%包覆的正极材料0.2 C首次放电容量达到195.9 mAh·g~(-1),1 C循环100周后容量保持率达到88.7%。     

LiNi0.6Co0.1Mn0.3O2材料的制备及其Nb2O5包覆改性

高镍层状LiNixCoyMn1-x-yO2（x≥0.6）三元材料具有较高的能量密度,但因锂镍混排、结构稳定性不佳等问题限制了其在锂离子电池中的应用。因此,采用Nb2O5包覆对三元材料LiNi0.6Co0.1Mn0.3O2（NCM613）进行改性,并考察了不同包覆量对NCM613的形貌结构和电化学性能的影响,得出了最佳工艺条件的包覆量为0.75%。首先,采用共沉淀法制备了前驱体Ni0.6Co0.1Mn0.3(OH)2;然后利用高温固相法制备了裸样LiNi0.6Co0.1Mn0.3O2（NCM613）;最后加入不同物质的量的Nb2O5粉末,通过球磨后高温烧结回火法制备了不同比例包覆量的Nb2O5@NCM613样品。XRD分析结果表明,各包覆样品与裸样NCM613的晶体结构相似,都具有完整的α-NaFeO2层状结构,阳离子混排程度较低;SEM分析结果表明,包覆样品和裸样NCM613均为1.0~1.5 μm的类球状粒子,且Ni、Co、Mn和Nb元素均匀分布在类球状材料表面;TEM分析结果表明,0.75Nb2O5@NCM613样品的Nb2O5包覆层厚度约为10~20 nm;材料电化学性能研究结果表明,在2.7~4.3 V、0.2C的电流密度条件下NCM613和0.75Nb2O5@NCM613的首圈放电比容量分别为208.11, 237.39 mA·h/g,1.0C循环100圈后,0.75Nb2O5@NCM613的放电比容量为176.43 mA·h/g,容量保持率高达86%。与裸样相比,在100圈循环后0.75Nb2O5@NCM613的阻抗明显降低,电化学极化降低,可逆性增强,这是因为Nb2O5包覆能提高材料的结构稳定性和电化学性能。可见,Nb2O5包覆高镍三元材料有利于推动高镍层状正极材料的工业化生产。     

锂离子电池正极材料LiNi0.5Mn0.5O2的合成

以Ni(OH)2、LiOH.H2O和MnO2为原料,采用机械活化-高温固相反应法在空气中合成了具有α-NaFeO2型层状有序结构的LiNi0.5Mn0.5O2,研究了合成产物的成分、物相、结构和形貌,以及物料在球磨和煅烧过程中的物理化学变化。采取高能球磨对原料进行机械活化,可提高物料的混合程度和反应活性,促进产物生成。合成的最佳工艺条件:高能球磨8 h,950℃下煅烧20 h,锂过量10%(摩尔比)。     

空气中合成锂离子电池正极材料LiNi1-xTixO2

以N i(OH)2、TiO2和LiOH.H2O为原料,采用固相反应法在空气中合成了LiN i1-xTixO2(x=0.025、0.050、0.100),用XRD研究了合成材料的物相和结构,用SEM研究了合成材料的形貌,用电池性能测试仪研究了合成材料的电化学性能.结果表明,原料中的n(Ti)/n(N i Ti)值对合成材料的结构和电化学性能影响很大.少量的钛可以进入LiN iO2的晶格形成LiN i1-xTixO2固溶体,而钛含量过大则会出现杂相.n(Ti)/n(N i Ti)值为0.050的样品结构有序度最高,充放电容量最大.     

锂离子电池正极材料LiNi0.8Co0.2O2的合成及性能研究

以硝酸盐和淀粉为原料,采用溶胶-凝胶方法合成LiNi_0.8Co_0.2O₂锂离子电池正极材料,利用X射线衍射（XRD）、扫描电镜(SEM)和电化学测试等方法对合成材料的结构、形貌以及电化学性能进行表征。结果表明,合成材料为单一晶相的α-NaFeO₂型层状结构,颗粒小且分布均匀,在电压为2.75~4.50 V (vs. Li+/Li) 范围内,以0.2 mA/cm2电流密度下经恒电流充放电测试,其首次放电比容量为183.1 mAh/g,经过50周充放电循环后放电比容量为171.3 mAh/g,表现出较大的初始放电比容量和良好的循环性能。     

锂离子电池正极材料LiNi_(0.8)Co_(0.2)的掺杂改性研究

采用共沉淀法和成LiNi0.8Co0.2O2,探讨影响锂离子电池正极材料LiNi0.8Co0.2O2电化学性能及结构的因素.为了提高材料的电化学性能,对材料进行了掺杂改性的研究,分别掺入Al、Mn、Mg和Fe四种元素.通过在2.8～4.2V范围内的充放电测试分析,掺入Mn的正极材料LiNi0.8Co0.1Mn0.1O2具有最高的放电比容量以及最低的容量损失,其首次放电容量为168.84 mAh/g,十次循环后的放电容量为166.9 mAh/g.     

球形正极材料LiNi0.8-xCo0.2AlxO2的合成与表征

以LiNO3、Al(NO3)3.9H2O、Co(NO3)2.6H2O和球形Ni(OH)2为原料,采用熔盐包裹法在空气中合成了LiNi0.8-xCo0.2AlxO2.采用XRD、SEM和电池性能测试仪研究了合成产物的结构、形貌和电化学性能.考察了合成温度、合成时间、掺铝量和锂过量对合成产物结构的影响.实验表明,采用熔盐包裹法在空气中合成的LiNi0.8-xCo0.2AlxO2具有α-NaFeO2型层状有序结构和球状形貌,并具有良好的电化学性能,其中LiNi0.7Co0.2Al0.1O2的最大放电比容量达到157.7 mAh/g.在空气中合成LiNi0.8-xCo0.2AlxO2的最佳工艺条件为合成温度750℃,合成时间16 h,锂过量10%(摩尔分数).     

锂离子电池三元正极材料[Li-Ni-Co-Mn-O]的研究进展

从制备性能、改性和安全性能3个方面,论述了锂离子电池三元正极材料[Li-Ni-Co-Mn-O]的研究现状,指出了其产业化所面临的问题,并给出了相应的对策.     

正极材料LiNi_（0.4）Mn_（0.4）Co_（0.2）O_2的制备和性能

采用草酸共沉淀法合成了锂离子正极材料LiNi0.4Mn0.4Co0.2O2。用XRD、SEM和充放电实验对合成产物的结构、形貌和电化学性能进行了表征;用DSC对合成产物在不同充电状态下的热稳定性进行了研究。结果表明,采用草酸共沉淀法合成的正极材料LiNi0.4Mn0.4Co0.2O2具有α-NaFeO2型层状结构,阳离子有序度高,粒度均匀适中,电化学性能良好,首次放电比容量达到158.7 mAh/g,30次循环后放电比容量还有144.8 mAh/g;过充电状态下具有良好的热稳定性。     

Synthesis and electrochemical characterization of LiNi0.78Co2Al0.02O2 cathode material in a novel co-precipitation method

LiNi0.78Co2Al0.02O2 cathode materials were prepared with a novel co-precipitation method followed by heat-treating. The properties of the materials were characterized. XRD patterns showed that no secondary phase appeared and the hexagonal lattice parameter c of LiNi0.78Co2Al0.02O2 was larger than that of LiNi0.8Co0.2O2. The SEM images indicated that the powders of the material were submicron size. The results of the ICP-AES analysis proved that elemental compositions of the material were similar to those of the targeted one. Cyclic voltammetry (3.0-4.2 V) illustrated that the new material had good lithium-ion intercalation/de-intercalation performance. The results of galvanostatic cycling showed that the initial specific discharge capacity of the prepared ma-terial was 181.4 mAh/g, and the specific discharge capacity was 177.3 mAh/g after 100 cycles (0.2C,3.0-4.2 V, vs. Li /Li) with the capacity retention ratio of 97.7%.     

Synthesis and electrochemical characterization of LiNi0.78Co0.2Al0.02O2 cathode material in a novel co-precipitation method

LiNi0.78 Co0.2 Al0.02O2 cathode materials were prepared with a novel co-precipitation method followed by heat-treating. The properties of the materials were characterized. XRD patterns showed that no secondary phase appeared and the hexagonal lattice parameter c of LiNi0.rsCoo.2AI~0202 was larger than that of LiNi0.8Co0.2O2. The SEM images indicated that the powders of the material were submicron size. The results of the ICP-AES analysis proved that elemental compositions of the material were similar to those of the targeted one. Cyclic voltammetry （3.0- 4. 2 V） illustrated that the new material had good lithium-ion intercalation/de-intercalation performance. The results of galvanostatic cycling showed that the initial specific discharge capacity of the prepared material was 181.4 mAh/g, and the specific discharge capacity was 177.3 mAh/g after 100 cycles （0. 2C, 3.0 - 4. 2 V, vs. Li^＋/Li） with the capacity retention ratio of 97.7%.     

Characteristics of LiCoO2, LiMn2O4 and LiNi0.45Co0.1Mn0.45O2 as cathodes of lithium ion batteries

LiNi0. 45 Co0. 10 Mn0. 4sO2 was synthesized from Li2CO3 and a triple oxide of nickel, cobalt and manganese at 950 ℃ in air. The structures and characteristics of LiNi0. 45 Co0.10 Mn0. 45 O2, LiCoO2 and LiMn2 O4 were investigated by XRD, SEM and electrochemical measurements. The results show that LiNi0.4s Co0.10 Mn0. 45 O2 has a layered structure with hexagonal lattice. The commercial LicoO2 has sphere-like appearance and smooth surfaces, while the LiMn2 O4 and LiNi0.45 Co0. 10 Mn0. 45 O2 consist of cornered and uneven particles. LiNi0. 45 Co0.10 Mn0. 45 O2 has a large disLiMn2 O4 and LiCoO2, respectively. LiCoO2 and LiMn2 O4 have higher discharge voltage and better rate-capability than LiNi0. 45Co0.10 Mn0. 45 O2. All the three cathodes have excellent cycling performance with capacity retention of above 89.3 % at the 250th cycle. Batteries with LiMn2 O4 or LiNi0.45 Co0.10 Mn0. 45 O2 cathodes show better safety performance under abusive conditions than those with LiCoO2 cathodes.     

Preparation of spherical and dense LiNi0.8Co0.2O2 lithium-ion battery particles by spray pyrolysis

With citric acid as a polymeric agent layered LiNi0.8Co0.2O2 materials were synthesized by a spray pyrolysis method. The LiNi0.sCo0.2O2 particles were characterized by means of XRD, SEM and TEM. The electrochemical performances of LiNi0.8Co0.2O2 particles were studied in a voltage window of 3.00-4.35 V and at a current density of 30 mA/g. The results show that in the pilot-scale spray pyrolysis process, the morphology of particles is dependent upon the precursor concentration and flux of carrier gas. The initial discharge capacity of the LiNi0.8Co0.2O2particles at 720 ℃ for 12 h is 187.3 mA.h/g, and the capacity remains 96.8% with excellent cycleability after 30 cycles. The LiNi0.8Co0.2O2 samples synthesized under the optimized conditions by the spray pyrolysis method shows a good electrochemical performance.     

LiNi_(1/3)Co_(1/3)Mn_(1/3)O_2+LiMn_2O_4/软碳体系电池的研究

选用锰酸锂(Li Mn2O4)、复合镍钴锰酸锂(Li Ni1/3Co1/3Mn1/3O2)按不同比例混合作为正极,软碳作为负极材料,制备复合镍钴锰酸锂与锰酸锂混合型锂离子全电池(简称混合型锂离子全电池),选择质量分数为15%,35%的Li Mn2O4与Li Ni1/3Co1/3Mn1/3O2混合作为正极活性物质进行实验,研究Li Mn2O4对锂离子全电池充放电性能、安全性能、倍率放电性能、脉冲功率特性等的影响。结果表明:Li Mn2O4质量分数为35%时,既提升了锂离子全电池的电性能,又保证了其较高的安全性能;常温下电流为1I1(I1代表1 h率放电电流)充放电循环预计寿命可达到1 500周,55℃高温下电流为0.5I1充放电循环335周容量保持在92%以上;在放电深度(DOD)10%~80%内10 s脉冲充放电状态下,混合型锂离子全电池阻抗均在9 mΩ以下,50%DOD时的10 s放电比功率在700 W/kg以上。     

以Mn3O4为锰源合成高性能LiMn2O4正极材料

以Mn3O4为锰源,采用固相反应法,在较低的温度(650℃)制得尖晶石LiMn2O4正极材料。采用X射线衍射(XRD)、扫描电镜(SEM)、循环伏安和恒流充放电等技术对其相组成、微结构和电化学性能进行表征。结果表明该正极材料结晶良好,一次粒径约为150 nm。它的电化学性能,尤其是循环性能,明显优越于在较高温度合成的LiMn2O4。在电流密度为74 mA?g-1时,测得比容量为128 mAh?g-1,在1 480 mA?g-1时,比容量为105 mAh?g-1;在室温、148 mA?g-1充放电200次循环后,容量保持率为93%。