Polyanion halide solid electrolyte material and preparation method and application thereof

Abstract

The invention discloses a polyanion halide solid electrolyte material as well as a preparation method and application thereof. The chemical formula of the halide solid electrolyte material is Li < 3 > YCl < 6-2x > Br < x > I < x >, wherein 0 < x < 3. The chemical formula of the halide solid electrolyte material is Li < 3 > YCl < 5.8 > Br < 0.1 > I < 0.1 >, Li < 3 > YCl < 5.6 > Br < 0.2 > I < 0.2 >, Li < 3 > YCl < 5.4 > Br < 0.3 > I < 0.3 >, Li < 3 > YCl < 5.2 > Br < 0.4 > I < 0.4 >, Li < 3 > YCl < 5.0 > Br < 0.5 > I < 0.5 >, Li < 3 > YCl < 4.8 > Br < 0.6 > I < 0.6 >, Li < 3 > YCl < 4.6 > Br < 0.7 > I < 0.7 >, Li < 3 > YCl < 4.4 > Br < 0.8 > I < 0.8 >, Li < 3 > YCl < 4.2 > Br < 0.9 > I < 0.9 >, Li < 3 > YCl < 4.0 > The invention provides a series of Li3YCl6-2xBrxIx by taking economical and efficient Li3YCl6 as a main body and combining with an anion mixing strategy, the Li3YCl6-2xBrxIx has high ionic conductivity of 1.98 mS cm <-1 > and low activation energy of 0.257 eV, and has good compatibility with a Li4Ti5O12 (LTO) positive electrode and a Li-In alloy negative electrode. The construction of the anion mixed state not only can reduce the binding effect of an anion frame on Li < + > migration and improve the ionic conductivity, but also can soften anion crystal lattices and reduce the activation energy. More importantly, due to the introduction of I <->, a LiI self-limiting passivation interface layer is generated in situ, so that the stability of a Li interface is enhanced.

Description

Technical Field

[0001] The present invention relates to a polyanion halide solid electrolyte material and a preparation method and application thereof, belonging to the technical field of rechargeable and dischargeable lithium ion batteries. Background Art

[0002] The popularity of new energy vehicles and mobile electronic devices has increased the demand for secondary batteries with higher energy density and higher safety. All-solid-state lithium batteries (ASSLBs) that use non-flammable solid electrolytes (SEs) instead of flammable organic electrolytes have the advantages of improving practicality and safety, and are an ideal choice to meet the growing demand for sustainable energy storage. Although ASSLBs, with so many advantages compared to liquid lithium batteries, are recognized as promising to promote the rapid development of the battery industry through continuous innovation, it is undeniable that the practical application of ASSLBs is still greatly hindered by its inherent properties, including: low ionic conductivity of SEs, interfacial incompatibility between SEs and Li negative electrodes, and loose solid-solid contact between SEs and positive electrodes. It can be found that SEs, as an important component of ASSLBs, play a major limiting role in the performance breakthrough of ASSLBs.

[0003] Patent CN 117936881 A discloses a multi-component doped halide solid electrolyte material, including Li a M b Q c X d The polyvalent cation doped halide solid electrolyte material shown or the formula Li α T β R γ Y δ The multi-element anion-doped halide solid electrolyte material is shown. The invention also provides a method for preparing the multi-element doped halide solid electrolyte material and a solid-state battery. The invention uses a multi-element doping method to construct a halide-containing solid electrolyte material. Due to the doping of multiple elements, the internal structure and chemical disorder are introduced, thereby promoting the improvement of the ion conductivity of the solid electrolyte. Furthermore, the multi-element cation doping strategy improves the high-voltage stability of the halide solid electrolyte, and the multi-element anion doping strategy improves the lithium negative electrode stability of the halide solid electrolyte.

[0004] Halide SEs have shown great development potential due to their inherent unique three-dimensional host ion framework structure, good mechanical properties and excellent lithium ion conduction and penetration. Despite this, the long-term cycling stability of ASSLBs based on halide SEs is still questioned due to the easy reducibility of non-Li metal cations in the structure. In order to achieve high cycling stability, the compatibility between SE and the positive and negative electrodes must be improved at the same time. On the negative electrode side, LiIn alloy is usually used instead of Li metal as the negative electrode, and the strategy of combining sulfide as the negative electrode electrolyte is used to deal with the negative electrode interface compatibility problem. However, this not only increases the difficulty of battery system integration, but also sulfide SEs and halide SEs have been shown to have inevitable side reactions. The compatibility problem of the positive electrode interface is mainly manifested in two aspects: on the one hand, the poor chemical and electrochemical stability of the solid-solid interface leads to continuous chemical and electrochemical reactions at the solid-solid interface of the positive electrode material, which makes Li + During the reaction, the electrolyte is gradually consumed, causing the battery capacity to decay. On the other hand, the volume effect of the solid electrolyte / positive electrode interface causes cracks to appear at the solid-solid interface of the positive electrode material, reducing the contact area between the positive electrode active material and the conductive agent and current collector, which greatly increases the battery impedance and reduces the battery capacity and cycle life. Therefore, the Li + Diffusion and softening of SE particles is an effective measure to improve the compatibility problem of the cathode interface. So far, few halide SEs can achieve good compatibility between cathode and anode.

[0005] In response to the above problems, this application is filed. Summary of the Invention

[0006] In view of the shortcomings of the prior art, the first object of the present invention is to provide a polyanion halide solid electrolyte material.

[0007] The second object of the present invention is to provide a method for preparing the above-mentioned polyanion halide solid electrolyte material.

[0008] The third object of the present invention is to provide an application of the above-mentioned polyanion halide solid electrolyte material.

[0009] In order to achieve the first purpose, the present invention is implemented by the following technical solution: a multi-anion halide solid electrolyte material, the chemical formula of the multi-anion halide solid electrolyte material is Li3YCl 6-2x Br x I x ; Among them, 0<x<3.

[0010] Preferably, the chemical formula of the polyanion halide solid electrolyte material is Li3YCl 5.8 Br 0.1 I 0.1、Li3YCl 5.6 Br 0.2 I 0.2 、Li3YCl 5.4 Br 0.3 I 0.3 、Li3YCl 5.2 Br 0.4 I 0.4 、Li3YCl 5.0 Br 0.5 I 0.5 、Li3YCl 4.8 Br 0.6 I 0.6 、Li3YCl 4.6 Br 0.7 I 0.7 、Li3YCl 4.4 Br 0.8 I 0.8 、Li3YCl 4.2 Br 0.9 I 0.9 、Li3YCl 4.0 Br 1.0 I 1.0 or Li3YCl 3.0 Br 1.5 I 1.5 .

[0011] In order to achieve the second object, the present invention is implemented by the following technical solution: a method for preparing a polyanion halide solid electrolyte material, comprising the following steps:

[0012] S1: LiCl, LiBr, LiI and YCl3 are manually ground and mixed according to the stoichiometric ratio of the electrolyte chemical formula (6-2x):x:x:1, and then ball-milled to obtain a mixed powder;

[0013] S2: cold-pressing the mixed powder into tablets to obtain a halide solid electrolyte material.

[0014] Preferably, the rotation speed of the ball milling process in step S1 is 200-600 rpm, and the ball milling time is 20-60 h.

[0015] Preferably, the manual grinding and mixing process in step S1 is carried out in a glove box and lasts for 10-30 minutes.

[0016] Preferably, the ball milling in step S1 is performed for 10 hours as one ball milling cycle, and after each ball milling cycle, the ball mill jar is transferred to a glove box for manual mixing.

[0017] Preferably, the ball mill is made of zirconium oxide, the mass ratio of ZrO2 balls to mixed powder is (15-45):1, the diameters of the ZrO2 balls are 10 mm and 5 mm, and the quantity ratio of the two is 1:5.

[0018] Preferably, the cold-pressing pressure in step S2 is 3-5t, and the holding time is 4-6min.

[0019] By adopting the above technical solutions, the anion doping project has a certain effect on improving the ionic conductivity and electrode compatibility of SEs. - The introduction of Br can form a dense and strong LiF passivation layer, partially filling the interface voids or holes, making the side reactions self-limiting and achieving kinetic stability for Li metal. - and I - The introduction of I can significantly enhance the ionic conductivity of halide SEs and improve their compatibility with Li metal. More importantly, I - The introduction of can increase the Li + transport capacity, thereby improving the compatibility of the positive electrode interface. In addition, the presence of amorphous components has a positive regulatory effect on improving the battery performance of ASSLBs, and the presence of defects helps to improve ionic conductivity. Based on the synthesis method of high-energy ball milling, doping anions (cations) in the halide SEs structure is an effective strategy to increase the concentration of defects and amorphous components. Based on this, this application can prepare a multi-anion halide solid electrolyte material by conducting a systematic study on halide solid electrolytes, laying a solid foundation for the development of all-solid-state lithium-ion batteries.

[0020] The third object of the present invention is the application of multi-anion halide solid electrolyte materials in all-solid-state lithium-ion batteries.

[0021] Preferably, the all-solid-state lithium-ion battery comprises a positive electrode, a negative electrode and an electrolyte, and the electrolyte is the multi-anion halide solid electrolyte material of the present invention.

[0022] Beneficial effects of the present invention:

[0023] (1) The present invention solves problems such as low ionic conductivity of SEs, interfacial incompatibility between SEs and the lithium negative electrode, and loose solid-solid contact between SEs and the positive electrode. The technical solution provided by the present invention can promote the development of lithium-ion batteries and provide a scientific basis and technical support for the application of all-solid-state lithium-ion batteries in actual production and life.

[0024] (2) The present invention takes economical and efficient Li3YCl6 as the main body and combines it with anion mixing strategy to provide a series of Li3YCl 6-2x Br x Ix , which has a value of 1.98 mS cm -1 The high ionic conductivity and low activation energy of 0.257 eV of Li4Ti5O 12 (LTO) positive electrode and Li-In alloy negative electrode have good compatibility. The construction of anion mixed state can not only reduce the anion framework to Li + The binding effect of migration improves ionic conductivity, and can also soften the anion lattice and reduce the activation energy. More importantly, I - The introduction of LiI enhances the stability of the Li interface by in situ generating a self-limiting passivation interface layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A series of Li3YCl prepared in Example 1 of the present invention 6-2x Br x I x XRD pattern of

[0026] Figure 2 A series of Li3YCl prepared in Example 1 of the present invention 6-2x Br x I x SEM images of

[0027] Figure 3 A series of Li3YCl prepared in Example 1 of the present invention 6-2x Br x I x AC impedance spectrum of the electrolyte assembled into a symmetrical battery;

[0028] Figure 4 A series of Li3YCl prepared in Example 1 of the present invention 6-2x Br x I x Arrhenius plot of electrolytes;

[0029] Figure 5 In Example 1 of the present invention, when x=0.6, Li3YCl 6-2x Br x I x The charge and discharge curves of an all-solid-state lithium-ion battery assembled with electrolyte at different rates.

[0030] Figure 6 In Example 1 of the present invention, when x=0.6, Li3YCl 6-2x Br x I x Electrolyte assembly into rate performance of all-solid-state lithium-ion batteries.

[0031] Figure 7In Example 1 of the present invention, when x=0.6, Li3YCl 6-2x Br x I x Cycling performance of all-solid-state lithium-ion batteries assembled with electrolytes. DETAILED DESCRIPTION

[0032] In order to make the technical means, creative features, objectives and effects achieved by the present invention easier to understand, the present invention is further described below in conjunction with specific implementation methods.

[0033] Example 1

[0034] A method for preparing a polyanion halide solid electrolyte material comprises the following steps:

[0035] S1: LiCl, LiBr, LiI and YCl3 are manually ground and mixed according to the stoichiometric ratio and ball milled to obtain a mixed powder;

[0036] S2: cold-pressing the mixed powder into tablets to obtain a halide solid electrolyte material.

[0037] In this embodiment, the rotation speed of the ball milling process in step S1 is 200 rpm, and the ball milling time is 60 h.

[0038] In this embodiment, the manual grinding and mixing process in step S1 is performed in a glove box and lasts for 10 minutes.

[0039] In this embodiment, the ball milling in step S1 is performed for 10 hours as one ball milling cycle. After each ball milling cycle, the ball mill jar is transferred to a glove box for manual mixing.

[0040] In this embodiment, the ball mill is made of zirconium oxide, the mass ratio of ZrO2 balls to mixed powder is 15:1, the diameters of the ZrO2 balls are 10 mm and 5 mm, and the quantity ratio between the two is 1:5.

[0041] In this embodiment, the cold pressing pressure in step S2 is 3t, and the holding time is 4 minutes.

[0042] Example 2

[0043] A method for preparing a polyanion halide solid electrolyte material comprises the following steps:

[0044] S1: LiCl, LiBr, LiI and YCl3 are manually ground and mixed according to the stoichiometric ratio and ball milled to obtain a mixed powder;

[0045] S2: cold-pressing the mixed powder into tablets to obtain a halide solid electrolyte material.

[0046] In this embodiment, the rotation speed of the ball milling process in step S1 is 500 rpm, and the ball milling time is 40 hours.

[0047] In this embodiment, the ball mill is made of zirconium oxide, and the mass ratio of ZrO2 balls to mixed powder is 25:1.

[0048] In this embodiment, the cold pressing pressure in step S2 is 5t, and the holding time is 6 minutes.

[0049] Other details are the same as in Example 1.

[0050] Example 3

[0051] A method for preparing a polyanion halide solid electrolyte material comprises the following steps:

[0052] S1: LiCl, LiBr, LiI and YCl3 are manually ground and mixed according to the stoichiometric ratio and ball milled to obtain a mixed powder;

[0053] S2: cold-pressing the mixed powder into tablets to obtain a halide solid electrolyte material.

[0054] In this embodiment, the rotation speed of the ball milling process in step S1 is 600 rpm, and the ball milling time is 20 hours.

[0055] In this embodiment, the manual grinding and mixing process in step S1 is performed in a glove box and lasts for 30 minutes.

[0056] In this embodiment, the ball mill is made of zirconium oxide, and the mass ratio of ZrO2 balls to mixed powder is 15:1.

[0057] Other details are the same as in Example 1.

[0058] Example 4

[0059] A method for preparing a polyanion halide solid electrolyte material comprises the following steps:

[0060] S1: LiCl, LiBr, LiI and YCl3 are manually ground and mixed according to the stoichiometric ratio and ball milled to obtain a mixed powder;

[0061] S2: cold-pressing the mixed powder into tablets to obtain a halide solid electrolyte material.

[0062] In this embodiment, the rotation speed of the ball milling process in step S1 is 500 rpm, and the ball milling time is 40 hours.

[0063] In this embodiment, the ball mill is made of zirconium oxide, and the mass ratio of ZrO2 balls to mixed powder is 45:1.

[0064] Other details are the same as in Example 1.

[0065] Example 5

[0066] A method for preparing a polyanion halide solid electrolyte material comprises the following steps:

[0067] S1: LiCl, LiBr, LiI and YCl3 are manually ground and mixed according to the stoichiometric ratio and ball milled to obtain a mixed powder;

[0068] S2: cold-pressing the mixed powder into tablets to obtain a halide solid electrolyte material.

[0069] In this embodiment, the ball mill is made of zirconium oxide, and the mass ratio of ZrO2 balls to mixed powder is 35:1.

[0070] Other details are the same as in Example 1.

[0071] Test Example 1

[0072] like Figure 1 As shown, XRD analysis was performed on a series of products obtained in Example 1. The results showed that as the Br - (r=196pm) and I - (r=216pm) With the increase of doping amount, the diffraction peak moves to a lower angle range, which means that the interplanar spacing increases. On the other hand, Br - and I - Substitution leads to a decrease in the diffraction peak intensity, which means that the preferred orientation is significantly reduced. Considering the influence of crystal growth anisotropy, the obvious decrease in preferred orientation may be beneficial to Li + The construction of 3D migration channels enables the optimization of ion migration paths.

[0073] like Figure 2 As shown in Figure 5, the samples with Br and I co-doping ratios all exhibit refined grain sizes due to the stronger lattice softness of iodide.

[0074] The AC impedance results of the samples are as follows Figure 3 As shown in the figure, it can be seen that when x = 0.6, the impedance of the electrolyte is the smallest and the ionic conductivity is 1.98mS cm -1 .

[0075] The activation energy test results are as follows Figure 4 As shown in the figure, it can be seen that when x = 0.6, the activation energy of the electrolyte is the lowest, 0.257 eV. The ionic conductivity and activation energy are shown in Table 1.

[0076] Table 1

[0077] x＝0 x＝0.2 x＝0.3 x＝0.4 x＝0.5 x＝0.6 x＝0.7 x＝0.8 x＝0.9 x＝1.0 <![CDATA[σ(mS cm -1 )]]> 0.15915 0.87369 1.22957 1.62842 1.75907 1.97704 1.6522 1.42689 0.70562 0.74168 <![CDATA[E a (eV)]]> 0.405 0.27 0.271 0.269 0.261 0.257 0.268 0.265 0.332 0.331

[0078] Test Example 2

[0079] The sample obtained in Example 1 with x=0.6 was applied to an all-solid-state lithium-ion battery. The positive electrode of the battery was lithium titanate, and the negative electrode was Li-In. The all-solid-state battery was tested using a blue-power test device.

[0080] like Figure 5 As shown, the charge and discharge curves at different rates, the charge and discharge cut-off voltage is 0.4-1.8V (vs.Li / Li-In), and the capacity is 156.1, 143.0, 140.2, 135.4, 131.8 and 121.9mA hg respectively. -1 .

[0081] like Figure 6 It shows that after a gradual activation process, when the rate returns to 0.2C, the capacity recovers to 157.1mA hg -1 , no obvious capacity decay.

[0082] Figure 7 The figure shows the cycle performance of the all-solid-state lithium-ion battery. It can be seen from the figure that the battery has excellent cycle stability.

[0083] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention. Therefore, the embodiments should be regarded as illustrative and non-restrictive in all respects. The scope of the present invention is defined by the appended claims rather than the foregoing description, and all changes that come within the meaning and range of equivalents of the claims are intended to be included therein.

[0084] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A polyanion halide solid electrolyte material, characterized in that: The chemical formula of the multi-anion halide solid electrolyte material is Li3YCl 6-2x Br x I x ; Among them, 0<x<3.

2. The polyanion halide solid electrolyte material according to claim 1, characterized in that: The chemical formula of the multi-anion halide solid electrolyte material is Li3YCl 5.8 Br 0.1 I 0.1 、Li3YCl 5.6 Br 0.2 I 0.2 、Li3YCl 5.4 Br 0.3 I 0.3 、Li3YCl 5.2 Br 0.4 I 0.4 、Li3YCl 5.0 Br 0.5 I 0.5 、Li3YCl 4.8 Br 0.6 I 0.6 、Li3YCl 4.6 Br 0.7 I 0.7 、Li3YCl 4.4 Br 0.8 I 0.8 、Li3YCl 4.2 Br 0.9 I 0.9 、Li3YCl 4.0 Br 1.0 I 1.0 or Li3YCl 3.0 Br 1.5 I 1.5 .

3. A method for preparing the polyanion halide solid electrolyte material according to claim 1 or 2, characterized in that: The steps include: S1: LiCl, LiBr, LiI and YCl3 are manually ground and mixed according to the stoichiometric ratio of the electrolyte chemical formula (6-2x):x:x:1, and then ball-milled to obtain a mixed powder; S2: cold-pressing the mixed powder into tablets to obtain a polyanion halide solid electrolyte material.

4. The method for preparing a polyanion halide solid electrolyte material according to claim 3, wherein: The rotation speed of the ball milling process in step S1 is 200-600 rpm, and the ball milling time is 20-60 h.

5. The method for preparing a polyanion halide solid electrolyte material according to claim 3, wherein: The manual grinding and mixing process in step S1 was carried out in a glove box and lasted for 10-30 min.

6. The method for preparing a polyanion halide solid electrolyte material according to claim 3, characterized in that: The ball milling in step S1 was performed for 10 h as one ball milling cycle. After each ball milling cycle, the ball mill was transferred to a glove box for manual mixing.

7. The method for preparing a polyanion halide solid electrolyte material according to claim 6, wherein: The ball mill is made of zirconium oxide, the mass ratio of ZrO2 balls to mixed powder is 15-45:1, the diameters of the ZrO2 balls are 10 mm and 5 mm, and the quantity ratio of the two is 1:

5.

8. The method for preparing a polyanion halide solid electrolyte material according to claim 3, wherein: The cold-pressed tablets in step S2 are formed at a pressure of 3-5t and a holding time of 4-6min.

9. Use of the multi-anion halide solid electrolyte material according to claim 1 or 2 in an all-solid-state lithium-ion battery.

10. The use according to claim 9, characterized in that The all-solid-state lithium-ion battery comprises a positive electrode, a negative electrode and an electrolyte, wherein the electrolyte is a polyanion halide solid electrolyte material.

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