Solid electrolyte, method of preparation thereof, and lithium secondary battery comprising same

Abstract

The present invention relates to a solid electrolyte, a method of manufacturing same, and a lithium secondary battery comprising same. Specifically, the present invention relates to a sulfide-based solid electrolyte comprising one type or more from among Li2O, Li2SO4, and P2O5, a method for preparing the sulfide-based solid electrolyte, and a lithium secondary battery comprising same.

Description

Solid electrolyte, method for producing same, and lithium secondary battery comprising same

[0001] The present invention relates to a solid electrolyte, a method for producing the same, and a lithium secondary battery comprising the same. Specifically, the present invention relates to a sulfide-based solid electrolyte comprising at least one of Li2O, Li2SO4, and P2O5, a method for producing the same, and a lithium secondary battery comprising the same.

[0002]

[0003] With the recent surge in demand for small power-driven devices such as IT mobile devices, electric bicycles, and compact electric vehicles, interest in high-capacity batteries is growing. Furthermore, improving the safety and energy density of these high-capacity batteries is emerging as key issues. Consequently, interest in all-solid-state batteries is growing to improve the safety of existing secondary batteries and increase their energy density, leading to active research into them. All-solid-state batteries replace the liquid electrolytes used in conventional lithium secondary batteries with solid electrolytes. Because they do not use flammable solvents, they eliminate the risk of ignition or explosion due to reactions such as the decomposition of conventional electrolytes, thereby improving battery safety. Furthermore, the ability to use lithium metal or lithium alloys as anode materials improves the energy density relative to the mass and volume of the battery. Inorganic solid electrolytes are typically used in these all-solid-state batteries, and solid electrolytes with compositions such as Li6PS5Cl with an argyrodite structure are being studied extensively. However, sulfide-based solid electrolytes have the problem of being difficult to handle in the general atmosphere due to side reactions with moisture, and improving this has become an important task.

[0004]

[0005] The technical problem to be solved by the present invention is to provide a solid electrolyte with improved moisture stability and initial capacity.

[0006] Another technical problem to be solved by the present invention is to provide a method for manufacturing a solid electrolyte having the aforementioned advantages.

[0007] Another technical problem to be solved by the present invention is to provide a lithium secondary battery including a solid electrolyte having the aforementioned advantages.

[0008]

[0009] A solid electrolyte according to one embodiment of the present invention can be expressed by the following chemical formula 1.

[0010] [Chemical Formula 1] Li x PS y O z Cl w (But, 4 < x ≤ 6, 4 < y < 5, 0 < z <0.1, 0.7 < w ≤ 1.)

[0011] A method for manufacturing a solid electrolyte according to another embodiment of the present invention comprises the steps of: preparing a lithium compound, a sulfur compound, and a halogen compound as raw materials; mixing the raw materials;

[0012] A step of forming a pellet by pressurizing the above mixture; and a step of heat-treating the pellet; are included, and a solid electrolyte represented by the following chemical formula 1 can be formed.

[0013] [Chemical Formula 1] Li x PS y O z Cl w (But, 4 < x ≤ 6, 4 < y < 5, 0 < z < 0.1, 0.7 < w ≤ 1.)

[0014] According to another embodiment of the present invention, a lithium secondary battery comprises: a positive electrode including a positive electrode active material; a negative electrode including a negative electrode active material; and a solid electrolyte positioned between the positive electrode and the negative electrode; wherein the solid electrolyte comprises Li2O, Li2SO -4And it includes at least one of P2O5 and can be expressed by the following chemical formula 1.

[0015] [Chemical Formula 1] Li x PS y O z Cl w (But, 4 < x ≤ 6, 4 < y < 5, 0 < z <0.1, 0.7 < w ≤ 1.)

[0016]

[0017] A solid electrolyte according to one embodiment of the present invention can provide a solid electrolyte having improved moisture stability and initial capacity compared to existing sulfide-based solid electrolytes by including at least one of Li2O, Li2SO4, and P2O5.

[0018] According to another embodiment of the present invention, a method for producing a solid electrolyte can provide a method for producing a solid electrolyte having the above-described advantages.

[0019] According to another embodiment of the present invention, a lithium secondary battery can provide a lithium secondary battery including a solid electrolyte having the above-described advantages.

[0020]

[0021] The terms first, second, and third, etc., are used to describe, but are not limited to, various parts, components, regions, layers, and / or sections. These terms are used solely to distinguish one part, component, region, layer, or section from another part, component, region, layer, or section. Accordingly, a first part, component, region, layer, or section described below may be referred to as a second part, component, region, layer, or section without departing from the scope of the present invention.

[0022] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the present invention. As used herein, the singular forms "a," "an," and "the" include plural forms as well, unless the context clearly dictates otherwise. The word "comprising," as used herein, specifies particular features, regions, integers, steps, operations, elements, and / or components, but does not exclude the presence or addition of other features, regions, integers, steps, operations, elements, and / or components.

[0023] When a part is referred to as being "on" or "over" another part, it can be directly on or over the other part, or there may be other parts intervening. Conversely, when a part is referred to as being "directly on" another part, there are no other parts intervening.

[0024] Although not defined otherwise, all terms, including technical and scientific terms, used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention pertains. Terms defined in commonly used dictionaries are further interpreted to have meanings consistent with the relevant technical literature and the present disclosure, and are not to be construed as ideal or overly formal unless otherwise defined.

[0025] Also, unless otherwise stated, % means weight%, and 1 ppm is 0.0001 weight%.

[0026] Hereinafter, a solid electrolyte according to one embodiment of the present invention will be described.

[0027] A solid electrolyte according to one embodiment can be expressed by the following chemical formula 1.

[0028] [Chemical Formula 1] Li x PS y O z Cl w(But, 4 < x ≤ 6, 4 < y < 5, 0 < z <0.1, 0.7 < w ≤ 1.)

[0029] For the above chemical formula 1, preferably, 5 < x ≤ 6, 4.5 < y < 5, 0 < z < 0.1, 0.8 < w ≤ 1. More preferably, 5.5 < x ≤ 6, 4.6 < y < 5, 0 < z < 0.1, 0.9 < w ≤ 1.

[0030] A solid electrolyte according to one embodiment may include Li2O.

[0031] Li2O may be included to improve the moisture stability of the solid electrolyte.

[0032] In a solid electrolyte according to one embodiment, the Li2O may be included in an amount of more than 0 and less than 2 mol% based on 100 mol% of the total amount of the solid electrolyte. Preferably, the Li2O may be included in an amount of more than 0 and less than 1 mol%. More preferably, the Li2O may be included in an amount of more than 0 and less than 0.6 mol%.

[0033] When the content of Li2O is within the aforementioned range, the moisture stability and discharge capacity of the solid electrolyte may be improved. On the other hand, when the content of Li2O is not within the aforementioned range, the moisture stability of the solid electrolyte may be reduced. In addition, as the content of Li2O, an impurity, increases, the occurrence of side reactions increases, which may lower the structural stability of the solid electrolyte.

[0034] A solid electrolyte according to one embodiment may further include at least one of Li2SO4 and P2O5.

[0035] In order to improve the moisture stability of the solid electrolyte, one or more of Li2SO4 and P2O5 may be additionally included.

[0036] In a solid electrolyte according to one embodiment, the Li2SO4 may be included in an amount of more than 0 and less than 3 mol% based on 100 mol% of the total amount of the solid electrolyte. Preferably, the Li2SO4 may be included in an amount of more than 0 and less than 2 mol%. More preferably, the Li2SO4 may be included in an amount of more than 0 and less than 1 mol%.

[0037] When the content of Li2SO4 is within the above-mentioned range, the moisture stability and discharge capacity of the solid electrolyte can be improved. On the other hand, when the content of Li2SO4 is not within the above-mentioned range, the moisture stability of the solid electrolyte can be reduced. In addition, when the content of Li2SO4, which is an impurity, increases, the amount of Li2SO4 that is not included in the solid electrolyte structure increases, which can cause the structure of the solid electrolyte to become unstable.

[0038] In a solid electrolyte according to one embodiment, the P2O5 may be included in an amount of more than 0 and less than 20 mol% based on 100 mol% of the total amount of the solid electrolyte. Preferably, the P2O5 may be included in an amount of more than 0 and less than 10 mol%. More preferably, the P2O5 may be included in an amount of more than 0 and less than 5 mol%.

[0039] When the content of P2O5 is within the above-mentioned range, the moisture stability and discharge capacity of the solid electrolyte can be improved. On the other hand, when the content of P2O5 is not within the above-mentioned range, the moisture stability of the solid electrolyte can be reduced. In addition, as the content of P2O5 increases, the concentration of Li relative to the concentration of P in the solid electrolyte decreases, which can reduce the discharge capacity.

[0040] A solid electrolyte according to one embodiment can satisfy the following equation 1.

[0041] [Formula 1] 0 ≤ [C Li2O ] 2 *[C Li2SO4 ] 2 *[C P2O5] < 2.25

[0042] (In the above equation 1, [C Li2O ], [C Li2SO4 ], [C P2O5 ] represents the mole percent (mol %) concentration of Li2O, Li2SO4, and P2O5 contained in the solid electrolyte, respectively, and [C Li2O ], [C Li2SO4 ], [C P2O5 ] at least one of which exceeds 0.)

[0043] Preferably, in the above equation 1, 0 ≤ [C Li2O ] 2 *[C Li2SO4 ] 2 *[C P2O5 ] < 1.60. More preferably, in the above equation 1, 0 ≤ [C Li2O ] 2 *[C Li2SO4 ] 2 *[C P2O5 ] < 0.80. More preferably, in the above formula 1, 0 ≤ [C Li2O ] 2 *[C Li2SO4 ] 2 *[C P2O5 ] may be ≤ 0.40.

[0044] In the above equation 1, [C Li2O ] 2 *[C Li2SO4 ] 2 *[C Li2SO4 ] value is within the above-mentioned range, the moisture stability and discharge capacity of the solid electrolyte can be improved. On the other hand, [C Li2O ] 2 *[C Li2SO4 ] 2 *[C P2O5 ] If the value is not within the above-mentioned range, problems such as reduced moisture stability and discharge capacity of the solid electrolyte may occur.

[0045] Hereinafter, a method for manufacturing a solid electrolyte according to another embodiment of the present invention will be described.

[0046] A method for manufacturing a solid electrolyte according to another embodiment comprises the steps of: preparing a lithium compound, a sulfur compound, and a halogen compound as raw materials; mixing the raw materials;

[0047] A step of forming a pellet by pressurizing the above mixture; and a step of heat-treating the pellet; are included, and a solid electrolyte represented by the following chemical formula 1 can be formed.

[0048] [Chemical Formula 1] Li x PS y O z Cl w (But, 4 < x ≤ 6, 4 < y < 5, 0 < z < 0.1, 0.7 < w ≤ 1.)

[0049] For the above chemical formula 1, preferably, 5 < x ≤ 6, 4.5 < y < 5, 0 < z < 0.1, 0.8 < w ≤ 1. More preferably, 5.5 < x ≤ 6, 4.6 < y < 5, 0 < z < 0.1, 0.9 < w ≤ 1.

[0050] In a method for manufacturing a solid electrolyte according to another embodiment, the lithium compound may be Li2S containing at least one of Li2O and Li2SO4 as an impurity.

[0051] As described above, when a lithium compound contains at least one impurity among Li2O and Li2SO4, the moisture stability can be improved compared to Li6PS5Cl, a conventional argyrodite-based solid electrolyte manufactured without containing impurities.

[0052] In the raw material preparation step of the method for manufacturing a solid electrolyte according to another embodiment, it may include additionally mixing at least one of Li2O, Li2SO4, and P2O5.

[0053] In addition to the impurities Li2O and Li2SO4 contained in the lithium compound described above, at least one of Li2O, Li2SO4, and P2O5 may be further mixed to improve moisture stability.

[0054] In a method for manufacturing a solid electrolyte according to another embodiment, the additionally mixed Li2O may be added in an amount of more than 0 and less than 2 mol% based on 100 mol% of the total amount of the raw material. Preferably, the Li2O may be included in an amount of more than 0 and less than 1 mol%. More preferably, the Li2O may be included in an amount of more than 0 and less than 0.6 mol%.

[0055] When the amount of Li2O added is within the above-mentioned range, the moisture stability and discharge capacity of the solid electrolyte can be improved. On the other hand, when the amount of Li2O added is not within the above-mentioned range, the moisture stability of the solid electrolyte can be reduced. In particular, when the amount of Li2O added is excessively increased, the residual Li2O not included in the structure can cause a side reaction, which can lower the structural stability of the solid electrolyte.

[0056] In a method for manufacturing a solid electrolyte according to another embodiment, the additionally mixed Li2SO4 may be added in an amount of more than 0 and less than 3 mol% based on 100 mol% of the total amount of raw materials. Preferably, the Li2SO4 may be included in an amount of more than 0 and less than 2 mol%. More preferably, the Li2SO4 may be included in an amount of more than 0 and less than 1 mol%.

[0057] When the amount of Li2SO4 added is within the above-mentioned range, the moisture stability and discharge capacity of the solid electrolyte can be improved. On the other hand, when the amount of Li2SO4 added is not within the above-mentioned range, the moisture stability of the solid electrolyte can be reduced. In addition, when the amount of Li2SO4 added increases, the amount of Li2SO4 that is not included in the solid electrolyte structure increases, which can cause the structure of the solid electrolyte to become unstable.

[0058] In a method for manufacturing a solid electrolyte according to another embodiment, the additionally mixed P2O5 may be added in an amount of more than 0 and less than 20 mol% based on 100 mol% of the total amount of raw materials. Preferably, the P2O5 may be included in an amount of more than 0 and less than 10 mol%. More preferably, the P2O5 may be included in an amount of more than 0 and less than 5 mol%.

[0059] When the amount of P2O5 added is within the above-mentioned range, the moisture stability and discharge capacity of the solid electrolyte can be improved. On the other hand, when the amount of P2O5 added is not within the above-mentioned range, the moisture stability of the solid electrolyte can be reduced. In addition, when the amount of P2O5 added increases, the Li concentration in the solid electrolyte decreases relative to the P concentration, so the discharge capacity can decrease.

[0060] Hereinafter, a lithium secondary battery according to another embodiment of the present invention will be described.

[0061] According to another embodiment, a lithium secondary battery comprises: a positive electrode including a positive electrode active material; a negative electrode including a negative electrode active material; and a solid electrolyte positioned between the positive electrode and the negative electrode; wherein the solid electrolyte is Li2O, Li2SO -4 And it includes at least one of P2O5 and can be expressed by the following chemical formula 1.

[0062] [Chemical Formula 1] Li x PS y O z Clw (But, 4 < x ≤ 6, 4 < y < 5, 0 < z <0.1, 0.7 < w ≤ 1.)

[0063] For the above chemical formula 1, preferably, 5 < x ≤ 6, 4.5 < y < 5, 0 < z < 0.1, 0.8 < w ≤ 1. More preferably, 5.5 < x ≤ 6, 4.6 < y < 5, 0 < z < 0.1, 0.9 < w ≤ 1.

[0064] In another embodiment, in a lithium secondary battery, the solid electrolyte may satisfy the following equation 1.

[0065] [Formula 1] 0 ≤ [C Li2O ] 2 *[C Li2SO4 ] 2 *[C P2O5 ] < 2.25

[0066] (In the above equation 1, [C Li2O ], [C Li2SO4 ], [C P2O5 ] represents the mole percent (mol %) concentration of Li2O, Li2SO4, and P2O5 contained in the solid electrolyte, respectively, and [C Li2O ], [C Li2SO4 ], [C P2O5 ] at least one of which exceeds 0.)

[0067] Preferably, in the above equation 1, 0 ≤ [C Li2O ] 2 *[C Li2SO4 ] 2 *[C P2O5 ] < 1.60. More preferably, in the above equation 1, 0 ≤ [C Li2O ] 2 *[C Li2SO4 ] 2 *[C P2O5 ] < 0.80. More preferably, in the above formula 1, 0 ≤ [C Li2O ] 2 *[C Li2SO4 ] 2 *[CP2O5 ] may be ≤ 0.40.

[0068] In the above equation 1, [C Li2O ] 2 *[C Li2SO4 ] 2 *[C P2O5 ] value is within the above-mentioned range, the moisture stability and discharge capacity of the solid electrolyte can be improved. On the other hand, [C Li2O ] 2 *[C Li2SO4 ] 2 *[C P2O5 ] If the value is not within the above-mentioned range, problems such as reduced moisture stability and discharge capacity of the solid electrolyte may occur.

[0069]

[0070] Hereinafter, examples, comparative examples, and experimental examples of the present invention will be described. However, the following examples are merely preferred embodiments of the present invention, and the present invention is not limited to these examples. Furthermore, various modifications and variations are possible within the scope of the claims, the detailed description of the invention, and the accompanying drawings, and such modifications may also fall within the scope of the present invention.

[0071] <Example 1> Li6PS 4.99 O 0.01 Preparation of Cl (containing Li2O:0.5 mol%; Li2SO4:0 mol%; P2O5:0 mol%)

[0072] The raw materials were mixed in the stoichiometric ratio so that 0.5 mol% of Li2O was included based on 100 mol% of the total solid electrolyte, and then mixed at a speed of 300 rpm for about 8 hours using a planetary mill. Afterwards, a pressure of 300 MPa was applied to form pellets, and the pellets were heat-treated at a temperature of 550°C in an Ar atmosphere to obtain Li6PS. 4.99 O 0.01 Cl was manufactured.

[0073] <Example 2> Li 5.88 PS 4.89O 0.01 Cl 0.98 Preparation of (including Li2O:0.5mol%; Li2SO4:0mol%; P2O5:1mol%)

[0074] Li containing 0.5 mol% of Li2O and 1 mol% of P2O5 5.88 PS 4.89 O 0.01 Cl 0.98 It was manufactured in the same manner as Example 1 except that a solid electrolyte of the composition was manufactured.

[0075] <Example 3> Li 5.88 PS 4.89 O 0.09 Cl 0.98 Preparation of (including Li2O:0.5mol%; Li2SO4:0.8mol%; P2O5:1mol%)

[0076] Li containing 0.5 mol% of Li2O, 0.8 mol% of Li2SO4, and 1 mol% of P2O5 5.88 PS 4.89 O 0.09 Cl 0.98 It was manufactured in the same manner as Example 1 except that a solid electrolyte of the composition was manufactured.

[0077] <Example 4> Li 5.71 PS 4.74 O 0.09 Cl 0.95 Preparation of (including Li2O:0.5mol%; Li2SO4:0.8mol%; P2O5:2.5mol%)

[0078] Li containing 0.5 mol% of Li2O, 0.8 mol% of Li2SO4, and 2.5 mol% of P2O5 5.71 PS 4.74 O 0.09 Cl 0.95 It was manufactured in the same manner as Example 1 except that a solid electrolyte of the composition was manufactured.

[0079] <Example 5> Li 5.43 PS 4.51 O 0.08 Cl 0.9Preparation of (including Li2O:0.5mol%; Li2SO4:0.8mol%; P2O5:5mol%)

[0080] Li containing 0.5 mol% of Li2O, 0.8 mol% of Li2SO4, and 5 mol% of P2O5 5.43 PS 4.51 O 0.08 Cl 0.9 It was manufactured in the same manner as Example 1 except that a solid electrolyte of the composition was manufactured.

[0081] <Example 6> Li 4.91 PS 4.08 O 0.08 Cl 0.82 Preparation of (including Li2O:0.5mol%; Li2SO4:0.8mol%; P2O5:10mol%)

[0082] Li containing 0.5 mol% of Li2O, 0.8 mol% of Li2SO4, and 10 mol% of P2O5 4.91 PS 4.08 O 0.08 Cl 0.82 It was manufactured in the same manner as Example 1 except that a solid electrolyte of the composition was manufactured.

[0083] <Comparative Example 1> Li4PS 3.33 O 0.06 Cl 0.67 Preparation of (including Li2O:0.5mol%; Li2SO4:0.8mol%; P2O5:20mol%)

[0084] Li4PS containing 0.5 mol% of Li2O, 0.8 mol% of Li2SO4, and 20 mol% of P2O5 3.33 O 0.06 Cl 0.67 It was manufactured in the same manner as Example 1 except that a solid electrolyte of the composition was manufactured.

[0085] <Comparative Example 2> Li 5.88 PS 4.89 O 0.31 Cl 0.98Preparation of (including Li2O:0.5mol%; Li2SO4:3mol%; P2O5:1mol%)

[0086] Li containing 0.5 mol% of Li2O, 3 mol% of Li2SO4, and 1 mol% of P2O5 5.88 PS 4.89 O 0.31 Cl 0.98 It was manufactured in the same manner as Example 1 except that a solid electrolyte of the composition was manufactured.

[0087] <Comparative Example 3> Li 5.71 PS 4.74 O 0.3 Cl 0.95 Preparation of (including Li2O:0.5mol%; Li2SO4:3mol%; P2O5:2.5mol%)

[0088] Li containing 0.5 mol% of Li2O, 3 mol% of Li2SO4, and 2.5 mol% of P2O5 5.71 PS 4.74 O 0.3 Cl 0.95 It was manufactured in the same manner as Example 1 except that a solid electrolyte of the composition was manufactured.

[0089] <Comparative Example 4> Li 5.43 PS 4.51 O 0.28 Cl 0.9 Preparation of (including Li2O:0.5mol%; Li2SO4:3mol%; P2O5:5mol%)

[0090] Li containing 0.5 mol% of Li2O, 3 mol% of Li2SO4, and 5 mol% of P2O5 5.43 PS 4.51 O 0.28 Cl 0.9 It was manufactured in the same manner as Example 1 except that a solid electrolyte of the composition was manufactured.

[0091] <Comparative Example 5> Li 4.91 PS 4.08 O 0.26 Cl 0.82Preparation of (including Li2O:0.5mol%; Li2SO4:3mol%; P2O5:10mol%)

[0092] Li containing 0.5 mol% of Li2O, 3 mol% of Li2SO4, and 10 mol% of P2O5 4.91 PS 4.08 O 0.26 Cl 0.82 It was manufactured in the same manner as Example 1 except that a solid electrolyte of the composition was manufactured.

[0093] <Comparative Example 6> Li 5.71 PS 4.74 O 0.96 Cl 0.95 Preparation of (including Li2O:0.5mol%; Li2SO4:10mol%; P2O5:2.5mol%)

[0094] Li containing 0.5 mol% of Li2O, 10 mol% of Li2SO4, and 2.5 mol% of P2O5 5.71 PS 4.74 O 0.96 Cl 0.95 It was manufactured in the same manner as Example 1 except that a solid electrolyte of the composition was manufactured.

[0095] <Comparative Example 7> Li 4.91 PS 4.08 O 0.83 Cl 0.82 Preparation of (including Li2O:0.5mol%; Li2SO4:10mol%; P2O5:10mol%)

[0096] Li containing 0.5 mol% of Li2O, 10 mol% of Li2SO4, and 10 mol% of P2O5 4.91 PS 4.08 O 0.83 Cl 0.82 It was manufactured in the same manner as Example 1 except that a solid electrolyte of the composition was manufactured.

[0097] <Comparative Example 8> Li 5.29 PS 4.26 O 0.13 Cl 1.57Preparation of (including Li2O:2mol%; Li2SO4:0.8mol%; P2O5:1mol%)

[0098] Li containing 2 mol% of Li2O, 0.8 mol% of Li2SO4, and 1 mol% of P2O5 5.29 PS 4.26 O 0.13 Cl 1.57 It was manufactured in the same manner as Example 1 except that a solid electrolyte of the composition was manufactured.

[0099] <Comparative Example 9> Li 5.14 PS 4.14 O 0.12 Cl 1.52 Preparation of (including Li2O:2mol%; Li2SO4:0.8mol%; P2O5:2.5mol%)

[0100] Li containing 2 mol% of Li2O, 0.8 mol% of Li2SO4, and 2.5 mol% of P2O5 5.14 PS 4.14 O 0.12 Cl 1.52 It was manufactured in the same manner as Example 1 except that a solid electrolyte of the composition was manufactured.

[0101] <Comparative Example 10> Li 4.89 PS 3.94 O 0.12 Cl 1.45 Preparation of (including Li2O:2mol%; Li2SO4:0.8mol%; P2O5:5mol%)

[0102] Li containing 2 mol% of Li2O, 0.8 mol% of Li2SO4, and 5 mol% of P2O5 4.89 PS 3.94 O 0.12 Cl 1.45 It was manufactured in the same manner as Example 1 except that a solid electrolyte of the composition was manufactured.

[0103] <Comparative Example 11> Li 4.42 PS 3.56 O 0.11 Cl 1.31Preparation of (including Li2O:2mol%; Li2SO4:0.8mol%; P2O5:10mol%)

[0104] Li2O was added at 2 mol%, Li2SO4 at 0.8 mol%, and P2O5 at 10 mol%. 4.42 PS 3.56 O 0.11 Cl 1.31 It was manufactured in the same manner as Example 1 except that a solid electrolyte of the composition was manufactured.

[0105]

[0106] <Experimental Example 1> Evaluation of ionic conductivity at 30℃ and 0.1C

[0107] Electrochemical evaluations were conducted on the solid electrolytes of Comparative Examples 1 and 2 and Examples 1 to 3 using a pressure cell. The electrolyte was added and densified to 300 MPa. Thereafter, the cell was clamped using a SUS electrode at a pressure of 70 MPa, and the impedance was measured by applying 10 mV at 25 degrees.

[0108] <Experimental Example 2> Moisture Stability Evaluation

[0109] After applying 0.5 g of solid electrolyte to the watch face, it was exposed to a dry room with a dew point of -45°C for 8 hours, and the ionic conductivity before and after exposure was compared and evaluated.

[0110] <Experimental Example 3> Electrochemical Characteristics Evaluation

[0111] After fabricating solid electrolyte pellets, the positive electrode was bonded to the top and the counter electrode, In, to the bottom, and the density was increased to 500 MPa. After assembling the all-solid-state battery cell, a formation cycle was performed at 0.1 C in a 30-degree chamber, and the life characteristics were evaluated at 0.5 C.

[0112] According to Table 1 below, it can be confirmed that the solid electrolyte according to the examples of the present invention has superior moisture stability and discharge capacity than Comparative Examples 1 to 11. In particular, it can be confirmed that the solid electrolyte of Examples 1 to 4 also has superior ionic conductivity compared to Comparative Examples 1 to 11.

[0113]

[0114] ClassificationLi2O content (mol%)Li2SO4 content (mol%)P2O5 content (mol%)Sulphide-based solid electrolyte (LSPCl) compositionIonic conductivity (mS / cm)Discharge capacity (mAh / g)Moisture stability (%)[C Li2O ] 2 *[C LiSO4 ] 2 *[C P2O5 ]Example 10.500Li6PS 4.99 O 0.01 Cl2.52203730Example 20.501Li 5.88 PS 4.89 O 0.01 Cl 0.98 2.45204760 Example 30.50.81Li 5.88 PS 4.89 O 0.09 Cl 0.98 2.31205770.16 Example 40.50.82.5Li 5.71 PS 4.74 O 0.09 Cl 0.95 2.2206810.4 Example 50.50.85Li 5.43 PS 4.51 O 0.08 Cl 0.9 2.06201790.8 Example 60.50.810Li 4.91 PS 4.08 O 0.08 Cl 0.82 1.86196831.6Comparative example 10.50.820Li4PS 3.33 O 0.06 Cl 0.67 1.66195613.2 Comparative Example 20.531Li 5.88 PS 4.89 O 0.31 Cl 0.98 2.18201732.25Comparative example 30.532.5Li5.71 PS 4.74 O 0.3 Cl 0.95 2.01193715.625Comparative Example 40.535Li 5.43 PS 4.51 O 0.28 Cl 0.9 1.881967011.25Comparison Example 50.5310Li 4.91 PS 4.08 O 0.26 Cl 0.82 1.041916322.5Comparative Example 60.5102.5Li 5.71 PS 4.74 O 0.96 Cl 0.95 1.871986662.5Comparison Example 70.51010Li 4.91 PS 4.08 O 0.83 Cl 0.82 1.7119356250Comparison Example 820.81Li 5.29 PS 4.26 O 0.13 Cl 1.57 1.93198632.56Comparison Example 920.82.5Li 5.14 PS 4.14 O 0.12 Cl 1.52 1.51199746.4Comparative Example 1020.85Li 4.89 PS 3.94 O 0.12 Cl 1.45 1.131956812.8Comparative example 1120.810Li 4.42 PS 3.56 O 0.11 Cl 1.31 0.861885925.6

Claims

1. Expressed by the following chemical formula 1, Solid electrolyte. [Chemical Formula 1] Li x PS y O z Cl w (But, 4 < x ≤ 6, 4 < y < 5, 0 < z < 0.1, 0.7 < w ≤ 1.) 2. In paragraph 1, The above solid electrolyte comprises Li2O. Solid electrolyte.

3. In paragraph 2, The above Li2O is contained in an amount greater than 0 and less than 2 mol% based on 100 mol% of the total amount of the solid electrolyte. Solid electrolyte.

4. In paragraph 2, The above solid electrolyte further comprises at least one of Li2SO4 and P2O5. Solid electrolyte.

5. In paragraph 4, The above Li2SO4 is contained in an amount greater than 0 and less than 3 mol% based on 100 mol% of the total amount of the solid electrolyte. Solid electrolyte.

6. In paragraph 4, The above P2O5 is included in an amount greater than 0 and less than 20 mol% based on 100 mol% of the total amount of the solid electrolyte. Solid electrolyte.

7. In paragraph 1, Satisfying the following equation 1, Solid electrolyte. [Formula 1] 0 ≤ [C Li2O ] 2 *[C Li2SO4 ] 2 *[C P2O5 ] < 2.25 (In the above equation 1, [C Li2O ], [C Li2SO4 ], [C P2O5] represents the mole percent (mol %) concentration of Li2O, Li2SO4, and P2O5 contained in the solid electrolyte, respectively, and [C Li2O ], [C Li2SO4 ], [C P2O5 ] at least one of which exceeds 0.) 8. Step of preparing lithium compounds, sulfur compounds, and halogen compounds as raw materials; A step of mixing the above raw materials; A step of forming the mixture by pressurizing to form pellets; and A step of heat treating the above pellets; Forming a solid electrolyte represented by the following chemical formula 1, Method for manufacturing a solid electrolyte. [Chemical Formula 1] Li x PS y O z Cl w (But, 4 < x ≤ 6, 4 < y < 5, 0 < z < 0.1, 0.7 < w ≤ 1.) 9. In paragraph 8, The above lithium compound is Li2S containing at least one impurity among Li2O and Li2SO4. Method for manufacturing a solid electrolyte.

10. In paragraph 8, In the above raw material preparation step, at least one of Li2O, Li2SO4, and P2O5 is additionally mixed, Method for manufacturing a solid electrolyte.

11. In paragraph 10, The additional Li2O added above is added in an amount of more than 0 and less than 2 mol% based on 100 mol% of the total amount of raw materials. Method for manufacturing a solid electrolyte.

12. In paragraph 10, The additional Li2SO4 added above is added in an amount of more than 0 and less than 3 mol% based on 100 mol% of the total amount of raw materials. Method for manufacturing a solid electrolyte.

13. In paragraph 10, The additional P2O5 added above is added in an amount of more than 0 and less than 20 mol% based on 100 mol% of the total amount of raw materials. Method for manufacturing a solid electrolyte.

14. A cathode comprising a cathode active material; A negative electrode comprising a negative active material; and A solid electrolyte positioned between the positive and negative electrodes; The above solid electrolyte is Li2O, Li2SO -4 And it contains at least one of P2O5 and is represented by the following chemical formula 1. Lithium secondary battery. [Chemical Formula 1] Li x PS y O z Cl w (But, 4 < x ≤ 6, 4 < y < 5, 0 < z < 0.1, 0.7 < w ≤ 1.) 15. In paragraph 14, The above solid electrolyte satisfies the following equation 1: Lithium secondary battery. [Formula 1] 0 ≤ [C Li2O ] 2 *[C Li2SO4 ] 2 *[C P2O5 ] < 2.25 (In the above equation 1, [C Li2O ], [C Li2SO4 ], [C P2O5 ] represents the mole percent (mol%) concentration of Li2O, Li2SO4, and P2O5 contained in the solid electrolyte, respectively, and [C Li2O ], [C Li2SO4 ], [C P2O5 ] at least one of which exceeds 0.)