CN102769147B

CN102769147B - Mg<2+>, Al<3+>, Zr<4+> and S<2-> ion co-doped garnet type solid electrolyte

Info

Publication number: CN102769147B
Application number: CN201210269090.5A
Authority: CN
Inventors: 水淼; 杨天赐; 舒杰; 程亮亮; 冯琳; 任元龙; 郑卫东; 高珊
Original assignee: Ningbo University
Current assignee: Ningbo University
Priority date: 2012-07-18
Filing date: 2012-07-18
Publication date: 2015-07-15
Anticipated expiration: 2032-07-18
Also published as: CN102769147A

Abstract

The invention discloses an Mg<2+>, Al<3+>, Zr<4+> and S<2-> ion co-doped garnet type solid electrolyte Li5La3Nb2O12 which is characterized by comprising the stoichiometric equation: Li[5+x+2y+z]La[3-x]MgxAlyZrzNb[2-y-z]O[12-m]Sm, wherein x is equal to 0.1-0.5, y is equal to 0.1-0.2, z is equal to 0.1-0.2, and m is equal to 0.1-0.3; and the solid electrolyte is formed by uniformly mixing Li2CO3, La2O3, MgO, Al2O3, ZrO2, Nb2O5 and thiourea in the molar ratio of (2.7-3.05):(1.25-1.45):(0.1-0.5):(0.05-0.1):(0.1-0.2):(0.8-0.9):(0.1-0.3), and ball milling, pressing and sintering. According to the invention, the lithium-ion conductivity greater than 10<-4>S/cm can be obtained at room temperature.

Description

A kind of Mg 2+, Al 3+, Zr 4+, S 2-ion co-doped garnet-type solid electrolyte

Technical field

The present invention relates to a kind of solid lithium-ion electrolyte and manufacture field.

Background technology

Lithium ion battery have volume, weight energy than high, voltage is high, self-discharge rate is low, memory-less effect, have extended cycle life, the high absolute advantage of power density, have in global portable power source market and exceed 30,000,000,000 dollars of/year shares and the occupation rate of market far exceeding other batteries, the chemical power source [Wu Yuping most with market development prospect, Wan Chunrong, Jiang Changyin, lithium rechargeable battery, Beijing: Chemical Industry Press, 2002.].Lithium rechargeable battery major part employing both at home and abroad is liquid electrolyte at present, liquid lithium ionic cell has some unfavorable factors, as: liquid organic electrolyte may be revealed, blast at too high a temperature thus cause security incident, the occasion that some are high to security requirement cannot be applied in; Liquid electrolyte lithium ion battery ubiquity Capacity fading problem, uses after a period of time due to electrode active material dissolving in the electrolyte, reaction and degradation failure [Z.R.Zhang, Z.L.Gong, and Y.Yang, J.Phys.Chem.B, 108,2004,17546.].And all-solid-state battery fail safe is high, substantially do not have Capacity fading, solid electrolyte also serves the effect of barrier film, simplifies the structure of battery; In addition, due to without the need to isolated air, also simplify the requirement to equipment in production process, configuration design also more convenient and flexible [Wen Zhaoyin, Zhu Xiujian, the Xu Xiaoxiong etc. of battery, the research of solid state secondary battery, the 12 Chinese solid-state ionics academic meeting paper collection, 2004.]。

In all-solid lithium-ion battery, the rate determining step that the migration rate of charge carrier in solid electrolyte is often far smaller than the ion diffusion rates in the Charger transfer of electrode surface and positive electrode and becomes in whole electrode reaction dynamics, therefore development has the inorganic solid electrolyte of higher li ionic conductivity is the key place building high performance lithium ion battery.The solid lithium-ion electrolyte with Practical significance will be researched and developed in addition, require that it can have good stability (to carbon dioxide and moisture stabilization) in the environment simultaneously, in order to enable the all-solid-state battery of composition use lithium metal to have high energy density as negative pole, also wish that solid state electrolysis mass-energy is stablized lithium metal and has higher decomposition voltage.Lithium ion solid electrolyte from having report at present: LLTO (Li, La) TiO ₃solid electrolyte has very high intracrystalline conductivity (10 ^-3about S/cm) and higher normal temperature total conductivity (10 ^-4s/cm-10 ^-5s/cm), but LLTO decomposition voltage is low, cannot form the above all-solid-state battery of discharge voltage 3.7V and unstable to lithium anode; There is the LiM of NASICON type polycrystalline ₂(PO ₄) ₃(M=Ti, Ge, Zr) is by tetrahedron PO ₄with octahedra MO ₆the grid structure of common composition, the coordination creating structural hole and can fill, making it possible to a large amount of Li ions, is a kind of up-and-coming high-lithium ion conductivity solid electrolyte.By the replacement of aliovalent ion, introducing hole or calking lithium ion can further improve ionic conductivity [Xiaoxiong Xu, ZhaoyinWen, ZhonghuaGu, et al., Solid State Ionics, 171,2004,207-212.] in the structure.As the Li that [woods ancestral Zuxiang, Li Shichun, silicate journal, 9 (3), 1981,253-257.] such as woods ancestral Zuxiang, Li Shichun find _1+xti _2-xga _xp ₃o1 ₂, Li _1+2xti _2-xmg _xp ₃o ₁₂, Li _1+xge _2-xcrxP ₃0 ₁₂, Li _1+xge _2-xal _xp ₃o ₁₂, Li _1+xti _2-xin _xp ₃o ₁₂etc. system or other are as Li _1+2x+2yal _xmg _yti _2-x-ysi _xp _3-xo ₁₂, Li _1+x+yal _xti _2-xsi _yp _3-yo ₁₂, Li _1+xal _xti _2-xp ₃o ₁₂etc. system, all there is higher lithium ion conductivity.But the normal temperature lithium ion conductivity of these systems is usually 10 ^-4s/cm-10 ^-6between S/cm, the requirement of non-film lithium ion battery to electrolytic conductivity can't be met very well.NASICON system is unstable to lithium anode equally in addition.W.Weppner etc. proposed a kind of solid electrolyte Li of new garnet structure in 2003 ₅la ₃m ₂o ₁₂(M=Nb, Ta) (Thangadurai, V., H.Kaack, et al., Journal of the American Ceramic Society, 86 (3) 2003,437-440.), this solid electrolytic confrontation lithium anode or even motlten metal lithium all highly stable, be the solid electrolyte that all-solid lithium-ion battery has using value.But pure Li ₅la ₃m ₂o ₁₂the electrical conductivity at room temperature of (M=Nb, Ta) only has 10 ^-6about S/cm.W.Weppner etc. reported K again in 2006 ⁺, In ³⁺the Li of single ion doping ₅la ₃m ₂o ₁₂(M=Nb, Ta) (Thangadurai, V.and W.Weppner, Journal of Solid State Chemistry 179 (4), 2006,974-984.).Normal temperature ionic conductivity has been brought up to 10 ^-5the S/cm order of magnitude.But the requirement of non-film lithium ion battery to electrolytic conductivity can't be met very well.

Ion doping improves a kind of very effective mode of solid lithium ion electrolytic conductivity, but the interaction of Doped ions and matrix is very complicated, the characteristic such as size, electronic structure, electronegativity of Doped ions all has a significant impact the ion conductivity of parent, and have interaction between different Doped ions, be promote lithium ion mobility or suppress the degree of lithium ion mobility and promotion and suppression all can have very large difference along with the ionic species mixed and concentration.The selection of Doped ions should meet transmission bottleneck and Li as far as possible in principle ⁺radius size is mated, Li ⁺, vacancy concentration weak with skeleton ionic bonding forces and Li ⁺moderate three conditions of ratio of concentration.The lithium ion mobility mechanism of this garnet-type solid electrolyte also not yet complete studied personnel is understood.Therefore the Garnet-type solid electrolyte of contamination to exploitation high-lithium ion conductivity studying Doped ions further has very important meaning.

Summary of the invention

Technical problem to be solved by this invention is a kind of Mg provided for existing background technology ²⁺, Al ³⁺, Zr ⁴⁺, S ^2-ion co-doped carbuncle type lithium ion solid electrolyte Li ₅la ₃nb ₂o ₁₂.First Mg is passed through ²⁺replace La ³⁺, Al ³⁺replace Nb ⁵⁺mode at a low price ionic compartmentation high valence ion produce extra calking lithium ion, increase the quantity of moving lithium ion in lattice; Mg simultaneously ²⁺ionic radius be less than La ³⁺, Al ³⁺ionic radius is less than Nb ⁵⁺ionic radius, both synergies make the contraction distortion that La-O is octahedra and the generation of Nb-O octahedron is certain, the migrating channels cross section of proper expand lithium ion, thus improve lithium ion conductivity; S ^2-part replaces O ^2-, S ^2-although compare O ^2-greatly, lithium ion mobility aisle spare may be reduced, but S ^2-electronegativity is little, weak to gap lithium ion active force, plays the effect promoting lithium ion mobility generally; Zr ⁴⁺part replaces Nb ⁵⁺contribute to reducing lithium ion mobility activation energy.These synergies make the normal temperature ionic conductivity of this solid electrolyte more than 10 ^-4s/cm, more close to the ionic conductivity of liquid electrolyte.

The present invention reaches by the following technical solutions, and this technical scheme provides a kind of lithium ion conductivity more than 10 ^-4the lithium ion solid electrolyte of S/cm, its stoichiometric equation is Li _5+x+2y+zla _3-xmg _xal _yzr _znb _2-y-zo _12-ms _mwherein: x=0.1-0.5; Y=0.1-0.2; Z=0.1-0.2; M=0.1-0.3.

In this technical scheme, by Li ₂cO ₃: La ₂o ₃: MgO: Al ₂o ₃: ZrO ₂: Nb ₂o ₅: thiocarbamide: for the ratio uniform of 2.7-3.05: 1.25-1.45: 0.1-0.5: 0.05-0.1: 0.1-0.2: 0.8-0.9: 0.1-0.3 (mol ratio) mixes, add 95% ethanol of 2%-6%, with the rotating speed ball milling 10-30 hour of 200-400 rev/min in ball mill, after ball milling terminates in 60 DEG C of-80 DEG C of vacuum drying ovens (vacuum degree is at 10Pa-100Pa) dry 10-30 hour, grind in alms bowl at agate after taking-up and again grind 10-30 minute, powder after grinding is incubated 2-8 hour with the ramp of 5-10 DEG C/min to 200-280 DEG C, then be incubated 5-10 hour with the ramp of 5-10 DEG C/min to 700-800 DEG C, then within 10-30 hour, make solid electrolyte powder with the ramp of 2-10 DEG C/min to 900-1050 DEG C of insulation.This powder mixing 1-5wt% be bonding agent (this bonding agent is PVC or PVA) under forcing press with keep under the pressure of 300-500MPa pressure 2-6 minute formed thin slice, this thin slice makes lithium ion solid electrolyte thin slice in 10-20 hour with the ramp of 10-20 DEG C/min to 950-1150 DEG C of insulation in air atmosphere.As Fig. 1 consists of Li _5.4la _2.9mg _0.1al _0.1zr _0.1nb _1.8o _11.9s _0.1solid electrolyte sheet is AC impedance figure under electrochemical workstation, and from figure, calculate conductivity is 7.1x10 ^-4s/cm.

Compared with prior art, the invention has the advantages that: adopt Mg ²⁺, Al ³⁺, Zr ⁴, S ^2-ion co-doped carbuncle type lithium ion solid electrolyte Li ₅la ₃nb ₂o ₁₂.Pass through Mg ²⁺replace La ³⁺, Al ³⁺replace Nb ⁵⁺mode at a low price ionic compartmentation high valence ion produce extra calking lithium ion, increase the quantity of moving lithium ion in lattice; Mg simultaneously ²⁺ionic radius be less than La ³⁺, Al ³⁺ionic radius is less than Nb ⁵⁺ionic radius, both synergies make the contraction distortion that La-O is octahedra and the generation of Nb-O octahedron is certain, the migrating channels cross section of proper expand lithium ion, thus improve lithium ion conductivity; S ^2-part replaces O ^2-, S ^2-although compare O ^2-greatly, lithium ion mobility aisle spare may be reduced, but S ^2-electronegativity is little, weak to gap lithium ion active force, plays the effect promoting lithium ion mobility generally; Zr ⁴⁺part replaces Nb ⁵⁺contribute to reducing lithium ion mobility activation energy.These synergies improve the conductivity of this carbuncle type solid lithium-ion electrolyte significantly.Be very beneficial for the structure of all-solid lithium-ion battery.

Accompanying drawing explanation

Fig. 1 is the AC impedance figure of lithium ion solid electrolyte thin slice under electrochemical workstation, frequency versus impedance and frequency-phase figure.

Embodiment

Below in conjunction with embodiment, the present invention is described in further detail.

Embodiment 1: by Li ₂cO ₃: La ₂o ₃: MgO: Al ₂o ₃: ZrO ₂, Nb ₂o ₅: thiocarbamide is the ratio uniform mixing of 2.81: 1.375: 0.25: 0.06: 0.13: 0.875: 0.15 (mol ratio), add 95% ethanol of 3.2%, with the rotating speed ball milling 10 hours of 250 revs/min in ball mill, the middle drying of 60 DEG C of vacuum drying ovens (vacuum degree 20Pa) 10 hours after ball milling terminates, grind in alms bowl at agate after taking-up and again grind 30 minutes, powder after grinding is incubated 3 hours with the ramp of 5 DEG C/min to 220 DEG C, then be incubated 10 hours with the ramp of 5 DEG C/min to 720 DEG C, then within 11 hours, make solid electrolyte powder with the ramp of 3 DEG C/min to 900 DEG C of insulations.This powder mixing 2wt% bonding agent PVC is to keep pressure to form thin slice in 5 minutes under forcing press under the pressure of 300MPa, this thin slice makes lithium ion solid electrolyte thin slice in 10 hours with the ramp of 11 DEG C/min to 1000 DEG C of insulations in air atmosphere.

Embodiment 2: by Li ₂cO ₃: La ₂o ₃: MgO: Al ₂o ₃: ZrO ₂: Nb ₂o ₅: thiocarbamide is the ratio uniform mixing of 2.94: 1.3: 0.4: 0.07: 0.2: 0.83: 0.16 (mol ratio), add 95% ethanol of 5.5%, with the rotating speed ball milling 15 hours of 380 revs/min in ball mill, the middle drying of 80 DEG C of vacuum drying ovens (vacuum degree 95Pa) 30 hours after ball milling terminates, grind in alms bowl at agate after taking-up and again grind 30 minutes, powder after grinding is incubated 5 hours with the ramp of 6 DEG C/min to 250 DEG C, then be incubated 10 hours with the ramp of 8 DEG C/min to 780 DEG C, then within 15 hours, make solid electrolyte powder with the ramp of 7 DEG C/min to 1000 DEG C of insulations.This powder mixing 5wt% bonding agent PVC to keep pressure to form thin slice in 2 minutes under the pressure of 450MPa, makes lithium ion solid electrolyte thin slice in 10 hours with the ramp of 15 DEG C/min to 1050 DEG C of insulations under this thin slice air atmosphere under forcing press.

Embodiment 3: by Li ₂cO ₃: La ₂o ₃: MgO: Al ₂o ₃: ZrO ₂: Nb ₂o ₅: thiocarbamide is the ratio uniform mixing of 2.7: 1.45: 0.1: 0.05: 0.1: 0.9: 0.12 (mol ratio), add 95% ethanol of 3%, with the rotating speed ball milling 20 hours of 300 revs/min in ball mill, the middle drying of 70 DEG C of vacuum drying ovens (vacuum degree 50Pa) 20 hours after ball milling terminates, grind in alms bowl at agate after taking-up and again grind 10 minutes, powder after grinding is incubated 5 hours with the ramp of 9 DEG C/min to 270 DEG C, then be incubated 7 hours with the ramp of 10 DEG C/min to 800 DEG C, then within 12 hours, make solid electrolyte powder with the ramp of 2 DEG C/min to 1050 DEG C of insulations.This powder mixing 1wt% bonding agent PVA is to keep pressure to form thin slice in 6 minutes under forcing press under the pressure of 300MPa, this thin slice makes lithium ion solid electrolyte thin slice in 18 hours with the ramp of 15 DEG C/min to 1100 DEG C of insulations in air atmosphere.

Embodiment 4: by Li ₂cO ₃: La ₂o ₃: MgO: Al ₂o ₃: ZrO ₂: Nb ₂o ₅: thiocarbamide is the ratio uniform mixing of 2.845: 1.35: 0.3: 0.06: 0.15: 0.865: 0.2 (mol ratio), add 95% ethanol of 5.5%, with the rotating speed ball milling 29 hours of 390 revs/min in ball mill, the middle drying of 80 DEG C of vacuum drying ovens (vacuum degree 100Pa) 10 hours after ball milling terminates, grind in alms bowl at agate after taking-up and again grind 20 minutes, powder after grinding is incubated 8 hours with the ramp of 5 DEG C/min to 250 DEG C, then be incubated 5 hours with the ramp of 8 DEG C/min to 750 DEG C, then within 20 hours, make solid electrolyte powder with the ramp of 9 DEG C/min to 1000 DEG C of insulations.This powder mixing 2.6wt% bonding agent PVA is to keep pressure to form thin slice in 4 minutes under forcing press under the pressure of 400MPa, this thin slice makes lithium ion solid electrolyte thin slice in 13 hours with the ramp of 20 DEG C/min to 1150 DEG C of insulations in air atmosphere.

Embodiment 5: by Li ₂cO ₃: La ₂o ₃: CaO: Al ₂o ₃: ZrO ₂: Nb ₂o ₅: thiocarbamide is the ratio uniform mixing of 2.995: 1.275: 0.45: 0.09: 0.18: 0.82: 0.3 (mol ratio), add 95% ethanol of 4%, with the rotating speed ball milling 10 hours of 210 revs/min in ball mill, the middle drying of 60 DEG C of vacuum drying ovens (vacuum degree 20Pa) 30 hours after ball milling terminates, grind in alms bowl at agate after taking-up and again grind 30 minutes, powder after grinding is incubated 2 hours with the ramp of 6 DEG C/min to 210 DEG C, then be incubated 10 hours with the ramp of 5 DEG C/min to 710 DEG C, then within 28 hours, make solid electrolyte powder with the ramp of 7 DEG C/min to 900 DEG C of insulations.This powder mixing 5wt% bonding agent PVC is to keep pressure to form thin slice in 2 minutes under forcing press under the pressure of 500MPa, this thin slice makes lithium ion solid electrolyte thin slice in 10 hours with the ramp of 10 DEG C/min to 950 DEG C of insulations in air atmosphere.

Claims

1. a Mg ²⁺, Al ³⁺, Zr ⁴⁺, S ^2-ion co-doped carbuncle type lithium ion solid electrolyte, is characterized in that stoichiometric equation is Li _5+x+2y+zla _3-xmg _xal _yzr _znb _2-y-zo _12-ms _m, wherein: x=0.1-0.5; Y=0.1-0.2; Z=0.1-0.2; M=0.1-0.3.

2. carbuncle type lithium ion solid electrolyte according to claim 1, is characterized in that Li ₂cO ₃: La ₂o ₃: MgO: Al ₂o ₃: ZrO ₂: Nb ₂o ₅: thiocarbamide mol ratio is the ratio uniform mixing of 2.7-3.05: 1.25-1.45: 0.1-0.5: 0.05-0.1: 0.1-0.2: 0.8-0.9: 0.1-0.3, add 95% ethanol of 2%-6%, with the rotating speed ball milling 10-30 hour of 200-400 rev/min in ball mill.

3. carbuncle type lithium ion solid electrolyte according to claim 1, is characterized in that the normal temperature lithium ion conductivity of the thin slice of the described solid electrolyte obtained is greater than 10 ^-4s/cm.