CN117154086A - 一种Fe/Mg掺杂调控的层状富锂正极材料、制备方法以及锂离子电池 - Google Patents
一种Fe/Mg掺杂调控的层状富锂正极材料、制备方法以及锂离子电池 Download PDFInfo
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- 229910052744 lithium Inorganic materials 0.000 title claims abstract description 37
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 title claims abstract description 35
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 title claims abstract description 24
- 229910001416 lithium ion Inorganic materials 0.000 title claims abstract description 24
- 238000002360 preparation method Methods 0.000 title claims abstract description 11
- 239000010406 cathode material Substances 0.000 title claims abstract description 10
- 230000001105 regulatory effect Effects 0.000 title abstract description 6
- 239000010405 anode material Substances 0.000 claims abstract description 13
- 238000000034 method Methods 0.000 claims abstract description 7
- KRKNYBCHXYNGOX-UHFFFAOYSA-N citric acid Chemical compound OC(=O)CC(O)(C(O)=O)CC(O)=O KRKNYBCHXYNGOX-UHFFFAOYSA-N 0.000 claims description 36
- 238000001354 calcination Methods 0.000 claims description 19
- 239000011777 magnesium Substances 0.000 claims description 19
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 17
- PXHVJJICTQNCMI-UHFFFAOYSA-N nickel Substances [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims description 17
- 239000011572 manganese Substances 0.000 claims description 12
- 239000007774 positive electrode material Substances 0.000 claims description 12
- 238000003756 stirring Methods 0.000 claims description 10
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 10
- YNQRWVCLAIUHHI-UHFFFAOYSA-L dilithium;oxalate Chemical compound [Li+].[Li+].[O-]C(=O)C([O-])=O YNQRWVCLAIUHHI-UHFFFAOYSA-L 0.000 claims description 8
- 229910052751 metal Inorganic materials 0.000 claims description 8
- 239000002184 metal Substances 0.000 claims description 8
- 239000012266 salt solution Substances 0.000 claims description 8
- 239000007864 aqueous solution Substances 0.000 claims description 6
- 239000003792 electrolyte Substances 0.000 claims description 6
- 239000011259 mixed solution Substances 0.000 claims description 6
- 238000005303 weighing Methods 0.000 claims description 6
- 238000001035 drying Methods 0.000 claims description 5
- 238000002156 mixing Methods 0.000 claims description 5
- 239000000243 solution Substances 0.000 claims description 5
- 230000009920 chelation Effects 0.000 claims description 4
- PVFSDGKDKFSOTB-UHFFFAOYSA-K iron(3+);triacetate Chemical compound [Fe+3].CC([O-])=O.CC([O-])=O.CC([O-])=O PVFSDGKDKFSOTB-UHFFFAOYSA-K 0.000 claims description 4
- 230000000630 rising effect Effects 0.000 claims description 3
- UHNWOJJPXCYKCG-UHFFFAOYSA-L magnesium oxalate Chemical compound [Mg+2].[O-]C(=O)C([O-])=O UHNWOJJPXCYKCG-UHFFFAOYSA-L 0.000 claims description 2
- RGVLTEMOWXGQOS-UHFFFAOYSA-L manganese(2+);oxalate Chemical compound [Mn+2].[O-]C(=O)C([O-])=O RGVLTEMOWXGQOS-UHFFFAOYSA-L 0.000 claims description 2
- DOLZKNFSRCEOFV-UHFFFAOYSA-L nickel(2+);oxalate Chemical compound [Ni+2].[O-]C(=O)C([O-])=O DOLZKNFSRCEOFV-UHFFFAOYSA-L 0.000 claims description 2
- 238000004321 preservation Methods 0.000 claims 1
- 239000000463 material Substances 0.000 abstract description 38
- 239000001301 oxygen Substances 0.000 abstract description 12
- 229910052760 oxygen Inorganic materials 0.000 abstract description 12
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 abstract description 11
- 229910052749 magnesium Inorganic materials 0.000 abstract description 9
- 229910052742 iron Inorganic materials 0.000 abstract description 7
- 230000002427 irreversible effect Effects 0.000 abstract description 6
- 229910052723 transition metal Inorganic materials 0.000 abstract description 6
- 150000003624 transition metals Chemical class 0.000 abstract description 4
- 238000012360 testing method Methods 0.000 description 11
- 229960004106 citric acid Drugs 0.000 description 7
- 230000000052 comparative effect Effects 0.000 description 6
- 239000000523 sample Substances 0.000 description 6
- 239000002245 particle Substances 0.000 description 5
- 239000008213 purified water Substances 0.000 description 5
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 4
- 229910052759 nickel Inorganic materials 0.000 description 4
- 238000006722 reduction reaction Methods 0.000 description 4
- 238000006243 chemical reaction Methods 0.000 description 3
- 238000002484 cyclic voltammetry Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 238000000227 grinding Methods 0.000 description 3
- 238000010438 heat treatment Methods 0.000 description 3
- 229910052748 manganese Inorganic materials 0.000 description 3
- -1 nickel oxalate tetrahydrate Chemical compound 0.000 description 3
- 230000033116 oxidation-reduction process Effects 0.000 description 3
- 230000009467 reduction Effects 0.000 description 3
- 238000003860 storage Methods 0.000 description 3
- 238000012546 transfer Methods 0.000 description 3
- YASYEJJMZJALEJ-UHFFFAOYSA-N Citric acid monohydrate Chemical compound O.OC(=O)CC(O)(C(O)=O)CC(O)=O YASYEJJMZJALEJ-UHFFFAOYSA-N 0.000 description 2
- UWFQSPBCWXGQLX-UHFFFAOYSA-L OC(C(O)=O)=O.O[Mn]O.O.O Chemical compound OC(C(O)=O)=O.O[Mn]O.O.O UWFQSPBCWXGQLX-UHFFFAOYSA-L 0.000 description 2
- 229910052782 aluminium Inorganic materials 0.000 description 2
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 2
- 229910052786 argon Inorganic materials 0.000 description 2
- 230000006399 behavior Effects 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 230000033228 biological regulation Effects 0.000 description 2
- 238000012512 characterization method Methods 0.000 description 2
- 229960002303 citric acid monohydrate Drugs 0.000 description 2
- 229910017052 cobalt Inorganic materials 0.000 description 2
- 239000010941 cobalt Substances 0.000 description 2
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 description 2
- 238000001816 cooling Methods 0.000 description 2
- 238000000840 electrochemical analysis Methods 0.000 description 2
- 239000007772 electrode material Substances 0.000 description 2
- 239000011888 foil Substances 0.000 description 2
- PJYWQDOJMBTCCO-UHFFFAOYSA-L magnesium;oxalate;dihydrate Chemical compound O.O.[Mg+2].[O-]C(=O)C([O-])=O PJYWQDOJMBTCCO-UHFFFAOYSA-L 0.000 description 2
- 230000014759 maintenance of location Effects 0.000 description 2
- 230000005012 migration Effects 0.000 description 2
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- 239000004570 mortar (masonry) Substances 0.000 description 2
- 238000006479 redox reaction Methods 0.000 description 2
- 238000003980 solgel method Methods 0.000 description 2
- 238000001228 spectrum Methods 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 229910001290 LiPF6 Inorganic materials 0.000 description 1
- 239000006230 acetylene black Substances 0.000 description 1
- 230000004913 activation Effects 0.000 description 1
- 239000013543 active substance Substances 0.000 description 1
- 238000005054 agglomeration Methods 0.000 description 1
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- 238000004458 analytical method Methods 0.000 description 1
- 125000000129 anionic group Chemical group 0.000 description 1
- 150000001450 anions Chemical class 0.000 description 1
- 239000011230 binding agent Substances 0.000 description 1
- 125000002091 cationic group Chemical group 0.000 description 1
- 150000001768 cations Chemical class 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
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- 229920002981 polyvinylidene fluoride Polymers 0.000 description 1
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- 229910052596 spinel Inorganic materials 0.000 description 1
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- 230000000087 stabilizing effect Effects 0.000 description 1
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- C01G53/40—Nickelates
- C01G53/42—Nickelates containing alkali metals, e.g. LiNiO2
- C01G53/44—Nickelates containing alkali metals, e.g. LiNiO2 containing manganese
- C01G53/50—Nickelates containing alkali metals, e.g. LiNiO2 containing manganese of the type [MnO2]n-, e.g. Li(NixMn1-x)O2, Li(MyNixMn1-x-y)O2
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Abstract
本发明涉及锂电池材料制备技术领域,具体为一种Fe/Mg掺杂调控的层状富锂正极材料、制备方法以及锂离子电池,本发明通过在具有R‑3m空间群结构的无钴富锂层状正极材料的基础上进行Fe和Mg的共同掺杂,来分别部分取代过渡金属层中的Mn和Li,制备出多元素掺杂的富锂层状正极材料。本发明制备的正极材料中,Fe元素的掺杂可以降低过渡金属与氧之间的共价性从而可以抑制首圈的不可逆氧损失,Mg元素取代锂可以降低Li/Ni混排,能够支撑层状结构,Fe和Mg这两种元素的引入稳定了材料的结构、提高了材料的循环性能和倍率性能,并明显缓解了LNMO的电压降,提升了材料的整体电化学性能。
Description
技术领域
本发明涉及锂电池材料制备技术领域,具体为一种Fe/Mg掺杂调控的层状富锂正极材料、制备方法以及锂离子电池。
背景技术
随着锂离子电池的应用的增加,其使用场地从消费电子产品到电动汽车,再涉及到智能电网,人们对于高能量密度锂离子电池的需求日渐紧迫,作为锂离子电池的重要组成部分,人们对具有良好发展前景的正极材料进行了大量研究。
结合阴离子和阳离子氧化还原反应,层状富锂氧化物(LLRO)作为下一代锂离子电池的候选正极材料脱颖而出,但是当前商业化的正极材料提供容量较低,无钴的富锂层状正极材料Li1.2NixMn0.8-xO2(以下称LNMO)具有高理论比容量、环境友好和成本较低的优势,但与含钴的富锂层状正极材料类似,仍然存在着不可逆的氧释放、首圈库伦效率低、循环倍率性能差和电压衰减较快等问题。
发明内容
本发明所要解决的技术问题是:现有的LNMO材料存在的首圈库伦效率和容量低、放电平均电压衰减和倍率性能较差的问题。
本发明通过在具有R-3m空间群结构的无钴富锂层状正极材料(LNMO)的基础上进行Fe和Mg的共同掺杂,来分别部分取代过渡金属层中的Mn和Li,制备出多元素掺杂的富锂层状正极材料(MF-LNMO),以解决上述问题。
为实现上述目的,本发明提供如下技术方案:
一种多元素掺杂的富锂层状正极材料,分子式为:Li1.2-xMgxFeyNi0.2Mn0.6-yO2,0<x<0.02,0<y<0.02。
优选的,所述分子式具体为:Li1.19Mg0.01Fe0.01Ni0.2Mn0.59O2。
优选的,所述的一种多元素掺杂的富锂层状正极材料的制备方法,包括如下步骤:
(1)制备金属盐溶液:按照分子式计量比称取草酸锂、草酸锰、草酸镍、醋酸铁、草酸镁,混合溶于水中,得到金属盐溶液;
(2)制备柠檬酸水溶液:称取柠檬酸,溶于水中,搅拌至完全溶解,得到柠檬酸水溶液;
(3)制备溶胶:将金属盐溶液逐滴加入至柠檬酸水溶液中螯合,持续搅拌混合溶液直至形成溶胶;
(4)将所述溶胶干燥处理后,进行煅烧处理,得到多元素掺杂的富锂层状正极材料。
优选的,所述步骤(1)和步骤(2)中纯净水均为15ml,所述步骤(1)中草酸锂的质量过量称取5%-15%。
优选的,所述步骤(3)中的搅拌温度为70℃-90℃,搅拌时间为4-5h。
优选的,所述步骤(4)中干燥处理的为100℃-130℃,保温时间为10-15h。
优选的,所述步骤(4)中煅烧处理为两次煅烧,其中第一次煅烧的温度为800℃-1000℃,煅烧时间为9h-12h;第二次煅烧的温度为900℃-1200℃,煅烧时间为14h-18h,两次煅烧的升温速率为3-7℃/min。
优选的,所述所述步骤(4)中得到的多元素掺杂的富锂层状正极材料储存条件为:真空储存或氩气手套箱中储存。
一种锂离子电池正极,所述正极包括所述的多元素掺杂的富锂层状正极材料。
一种锂离子电池,包括电池壳体、电极组和电解液,电极组和电解液密封在电池壳体内,电极组包括正极、隔膜和负极,所述锂离子电池包括所述的一种锂离子电池正极。
与现有技术相比,本发明的有益效果为:
本发明选取Fe和Mg两种元素进行共掺杂调控材料组分,Fe3+与Mn4+具有相似的离子半径和电负性,Fe元素的掺杂可以降低过渡金属与氧之间的共价性从而可以抑制首圈的不可逆氧损失;Mg2+半径接近锂离子,因此Mg可以同时取代锂层和过渡金属层的锂,Mg元素取代锂可以降低Li/Ni混排,能够支撑层状结构。
Fe和Mg这两种元素的引入稳定了材料的结构、提高了材料的倍率性能,并明显缓解了LNMO的电压降,提升了材料的整体电化学性能。
附图说明
图1为(a)MF-LNMO和(b)LNMO的XRD精修图谱;
图2为材料(a)MF-LNMO和(b)LNMO的扫描电镜图;
图3为(a)样品材料MF-LNMO中Ni、Mn、Mg、Fe元素的分布图;(b)对比样LNMO中Ni和Mn元素的分布图;
图4为(a)MF-LNMO和(b)LNMO在电压窗口为2-4.8V,扫描速度为0.1mV/s时的循环伏安曲线;
图5为(a)MF-LNMO和(b)LNMO材料在0.1C的倍率下首圈充放电的电压-比容量图;
图6为MF-LNMO和LNMO正极材料在1C下,电压范围为2-4.8V区间的(a)循环150圈的平均电压-循环圈数图和(b)循环160圈的放电比容量-循环圈数图;
图7为(a)MF-LNMO和(b)LNMO正极材料在0.1C、0.2C、0.5C、1C、2C各倍率下循环五圈的比容量-循环圈数图;各倍率电流密度下(c)MF-LNMO和(d)LNMO的首圈充放电曲线;
图8为(a)MF-LNMO和(b)LNMO正极的EIS测试图谱和拟合图谱。
具体实施方式
下面将结合本发明实施例中的附图,对本发明实施例中的技术方案进行清楚、完整地描述,显然,所描述的实施例仅仅是本发明一部分实施例,而不是全部的实施例。基于本发明中的实施例,本领域普通技术人员在没有做出创造性劳动前提下所获得的所有其他实施例,都属于本发明保护的范围。
实施例1
使用溶胶凝胶法制备MF-LNMO(Li1.19Mg0.01Fe0.01Ni0.2Mn0.59O2):按照分子质量比称取草酸锂、四水合草酸锰、四水合草酸镍、醋酸铁和二水合草酸镁,混合溶于15ml纯净水中,放入磁子加热搅拌至溶液澄清,其中草酸锂过量10%,弥补后续反应带来的锂损失;将一水合柠檬酸同样溶于15ml纯净水中搅拌至溶解。二者都搅拌均匀后,将金属盐溶液逐滴加入至柠檬酸水溶液中螯合,形成绿色混合溶液,将混合溶液在80℃的温度下搅拌4h。待形成溶胶后,将材料放入恒温烘箱中以120℃保温12h,再将材料转移至马弗炉中,以850℃煅烧10h,研磨碎后,再次以950℃煅烧15h,升温速率为5度/分钟,之后随炉冷却,取出合成的材料,使用研钵磨碎后得到多元素掺杂的富锂层状正极材料。
对比例1
使用溶胶凝胶法制备LNMO(Li1.2Ni0.2Mn0.6O2):按照分子质量比称取草酸锂、四水合草酸锰、四水合草酸镍、醋酸铁和二水合草酸镁,混合溶于15ml纯净水中,放入磁子加热搅拌至溶液澄清,其中草酸锂过量10%,弥补后续反应带来的锂损失;将一水合柠檬酸同样溶于15ml纯净水中搅拌至溶解。二者都搅拌均匀后,将金属盐溶液逐滴加入至柠檬酸水溶液中螯合,形成绿色混合溶液,将混合溶液在80℃的温度下搅拌4h。待形成溶胶后,将材料放入恒温烘箱中以120℃保温12h,再将材料转移至马弗炉中,以950℃煅烧10h,升温速率为5度/分钟,之后随炉冷却,取出合成的材料,使用研钵磨碎后得到富锂层状正极材料。
试验例1:材料的表征
(a)实施例材料MF-LNMO和对比例材料LNMO的结构主要通过XRD进行表征,XRD的型号为德国Bruker D8X射线粉末衍射仪,结果如图1所示,分析衍射峰可知材料具有R-3m空间群结构;材料的形貌和尺寸主要通过SEM和TEM进行表征,其中SEM为日本的TOPCN DS-720仪器,结果如图2所示,可以观察到这两种材料呈现出不规则的形状,并且均有些许一次颗粒团聚现象。MF-LNMO的颗粒尺寸略小于LNMO,前者粒径在200-400nm之间,后者粒径则在300-500nm间,尺寸较小的正极材料颗粒有利于稳定电化学测试时的循环性能和倍率性能。
(b)能谱仪测试结果如图3所示,MF-LNMO中的Ni、Mn和掺杂元素Mg、Fe四种过渡金属元素均匀的分布在材料内,对比例中的元素也均匀分布。
综上所述,使用溶胶凝胶-高温固相烧结结合的合成方法可以合成粒径较小、各元素分布均匀的MF-LNMO样品。
试验例2:电化学性能测试
MF-LNMO和LNMO材料的电化学性能测试所使用的电池壳为CR2032的扣式电池壳套装,包含一个正极和一个金属锂负极。其中正极是由80%的正极活性材料,10%的导电剂乙炔黑和10%的粘结剂PVdF组成。然后将其均匀地涂覆在集流体铝箔上,放入真空烘箱120℃干燥5小时保证完全除去水分和其他有机液体,其中活性物质在电极中的负载量为1-2mg/cm2。电池组装是在无水无氧的氩气手套箱内进行的,其中电解液为1mol/L的LiPF6溶解在无水EC:DEC:EMC溶剂中,每个电池所滴加的电解液均为100微升,玻璃纤维膜作为电池隔膜。电池的充放电测试是在中国武汉蓝电有限公司Land BT2000电池测试***上进行的,其中测试温度为室温,电压测试窗口为2-4.8V,测试前电池需静置8小时以上。电池的循环伏安测试是在上海辰华仪器有限公司CHI 660E***上进行测试的。
(1)为了研究Mg元素和Fe元素两者调控LNMO组分后对该原始样电化学性能的影响,我们对改性后的样品MF-LNMO和对比样LNMO进行了锂离子半电池的组装并进行电化学测试,采用循环伏安法来探究两种材料在电化学行为中的氧化还原行为。
如图4所示,在首圈充电过程中,两种材料在4.0V左右均出现两个小峰,主要对应于Ni2+/3+和Ni3+/4+的氧化还原和锂离子的脱出;当电压超过4.5V时,二者也会出现一个较高的峰对应阴离子氧化还原。在放电时,首圈循环只有约3.75V出现还原峰,此处为Ni4+还原为Ni2+。到了后续循环的放电过程中,位于3.25V附近开始出现还原峰,这是首圈结束后Mn4+开始出现还原反应。对于MF-LNMO,其后两圈可逆性优于LNMO,充放电时氧化还原电位差低于对比样LNMO,极化较小。MF-LNMO在首圈充放电过程中具有更高的容量,此处应为Fe3+/3+δ存在氧化还原反应,这种可变价态赋予了这种材料额外的容量。MF-LNMO的4.5V以上的峰强小于对比样,这表明双掺杂抑制了结构中的氧释放,这是因为金属-氧共价降低而导致活化过程中氧损失较小。
(2)LNMO材料在首圈充电至高电压时会出现锂离子的脱出,氧的不可逆释放现象随之而来,因此这类材料的首圈库伦效率较低。从图5可以发现Mg和Fe的引入使材料电化学循环时的首圈库伦效率由原先的75.01%上升到82.78%,且提高了放电比容量。这表明MF-LNMO中的过渡金属与氧的键合得到了增强,使氧的不可逆氧化还原被抑制,容量利用率得到提升。
(3)为了探究Mg和Fe调控LNMO组分后对于原材料循环性能的影响,我们进行了MF-LNMO和LNMO在1C(250mA/g)的电流密度下,电压范围为2-4.8V时的恒流充放电测试。MF-LNMO的首圈放电比容量可达197.9mAh/g,循环160圈后容量保持率可达85.79%,而LNMO样品经相同的循环后容量仅剩71.29%。LNMO材料循环时会逐渐有尖晶石结构的出现,因此该材料作为正极活性物质进行电化学测试时往往展现出较大的电压衰减(即平均电池电压的降低)。为了研究Mg、Fe引入对LNMO原始材料的电压衰减的影响,本工作进行了1C下的循环性能测试,如图6所示,在循环150圈后,MF-LNMO展现出0.813mV/周期的平均电压降,而对比样LNMO则显示出更为严重的电压衰减,约为2.054mV/周期。Mg2+的掺杂可以减少Li/Ni阳离子混排程度并具有稳定的支柱效应;Fe3+的掺杂则增强了TM-O键能,稳定了部分晶格氧反应。
综上所述,MF-LNMO结构的不可逆相变得到了抑制,其容量保持率得到了提升,电压衰退情况获得了缓解。
(4)MF-LNMO和LNMO的倍率性能如图7所示,MF-LNMO在0.1C、0.2C、0.5C、1C、2C的倍率下循环五圈时首圈放电比容量分别是253.8、238.8、214、193.8、173.9mAh/g,而当电流密度回到0.1C时,放电比容量仍可达到250mAh/g;而对比样LNMO材料虽然在低倍率下具有较高的放电比容量,但在各电流密度下充放电循环后容量迅速下降至147.7mAh/g,说明MF-LNMO对于强电流密度的耐受力优于LNMO。图7也展示了两种材料在各倍率下的充放电曲线。
综上所述,MF-LNMO的倍率性能胜于LNMO,说明MF-LNMO经组分调控后具有更加稳定的结构,锂离子在整体结构中可以实现更快速的脱嵌,迁移速率加快,应用潜力更好。
(5)为了进一步探究MF-LNMO和对比样LNMO作为正极材料时电池的阻抗来研究其电化学机理,我们对二者做了EIS表征,如图8展示了MF-LNMO和LNMO的原始图谱、拟合的阻抗图谱和等效电路。图中所示意的电荷转移电阻代表了锂离子电池中锂离子在材料中迁移时遇到的阻力。图谱中包含一个中频区域的半圆和一条低频区域的斜线,其中前者指电荷转移阻抗(Rct),后者指整体材料的Warburg阻抗以反应扩散过程。MF-LNMO电极的Rct为188.2Ω,原始样LNMO的电阻为337.3Ω。经Mg、Fe引入后的电极材料小于原始LNMO电极材料的电荷转移阻抗,这表明了在MF-LNMO中锂离子的迁移速率更快,遇到的阻力更小。
综上所述,MF-LNMO展现出比LNMO更优异的动力学性能、更高的电导率和电化学活性。
对于本领域技术人员而言,显然本发明不限于上述示范性实施例的细节,而且在不背离本发明的精神或基本特征的情况下,能够以其他的具体形式实现本发明。因此,无论从哪一点来看,均应将实施例看作是示范性的,而且是非限制性的,本发明的范围由所附权利要求而不是上述说明限定,因此旨在将落在权利要求的等同要件的含义和范围内的所有变化囊括在本发明内。不应将权利要求中的任何附图标记视为限制所涉及的权利要求。
Claims (9)
1.一种多元素掺杂的富锂层状正极材料,其特征在于,分子式为:Li1.2- xMgxFeyNi0.2Mn0.6-yO2,0<x<0.02,0<y<0.02。
2.根据权利要求1所述的一种多元素掺杂的富锂层状正极材料,其特征在于,所述分子式为:Li1.19Mg0.01Fe0.01Ni0.2Mn0.59O2。
3.根据权利要求1所述的多元素掺杂的富锂层状正极材料的制备方法,其特征在于,包括如下步骤:
(1)制备金属盐溶液:按照分子式计量比称取草酸锂、草酸锰、草酸镍、醋酸铁、草酸镁,混合溶于水中,得到金属盐溶液;
(2)制备柠檬酸水溶液:称取柠檬酸,溶于水中,搅拌至完全溶解,得到柠檬酸水溶液;
(3)制备溶胶:将金属盐溶液逐滴加入至柠檬酸水溶液中螯合,持续搅拌混合溶液直至形成溶胶;
(4)将所述溶胶干燥处理后,进行煅烧处理,得到多元素掺杂的富锂层状正极材料。
4.根据权利要求3所述的多元素掺杂的富锂层状正极材料的制备方法,其特征在于,所述步骤(1)中草酸锂的质量过量称取5%-15%。
5.根据权利要求3所述的多元素掺杂的富锂层状正极材料的制备方法,其特征在于,所述步骤(3)中的搅拌温度为70℃-90℃,搅拌时间为4-5h。
6.根据权利要求3所述的多元素掺杂的富锂层状正极材料的制备方法,其特征在于,所述步骤(4)中干燥处理的温度为100℃-130℃,保温时间为10-15h。
7.根据权利要求3所述的多元素掺杂的富锂层状正极材料的制备方法,其特征在于,所述步骤(4)中煅烧处理为两次煅烧,其中第一次煅烧的温度为800℃-1000℃,煅烧时间为9h-12h;第二次煅烧的温度为900℃-1200℃,煅烧时间为14h-18h,两次煅烧的升温速率为3-7℃/min。
8.一种锂离子电池正极,其特征在于,所述正极包括权利要求1所述的多元素掺杂的富锂层状正极材料。
9.一种锂离子电池,包括电池壳体、电极组和电解液,电极组和电解液密封在电池壳体内,电极组包括正极、隔膜和负极,其特征在于,所述锂离子电池包括权利要求8所述的一种锂离子电池正极。
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