Polymer solid electrolyte membrane and preparation method thereof, solid-state battery, battery pack and electric equipment

Abstract

The invention provides a polymer solid electrolyte membrane and a preparation method thereof, a solid-state battery, a battery pack and electric equipment. The polymer solid electrolyte membrane comprises an inorganic separation membrane framework, the inorganic separation membrane framework comprises a plurality of straight through holes, and at least part of the straight through holes are filled with first polymer electrolyte and first lithium salt; the crystallinity of the first polymer electrolyte is not greater than 30%. The polymer solid electrolyte membrane provided by the invention has relatively high mechanical strength, good flexibility and high ionic conductivity at the same time.

Description

Technical Field

[0001] This invention relates to the field of batteries, and more particularly to a polymer solid electrolyte membrane and its preparation method, a solid battery, a battery pack, and electrical equipment. Background Technology

[0002] Compared to inorganic solid electrolytes, polymer solid electrolyte membranes have good flexibility and low interfacial impedance. However, polymer solid electrolyte membranes have low ionic conductivity and low mechanical strength. The low ionic conductivity affects the performance of the battery, while the low mechanical strength makes them easy to be pierced by lithium dendrites and cause short circuits when used with lithium metal anodes.

[0003] Introducing a three-dimensional network structure into polymers can improve the ionic conductivity of polymer solid electrolyte membranes, but the improvement in mechanical strength is very limited. Polymer solid electrolyte membranes are still easily pierced by lithium dendrites, and the transport path of lithium ions in polymer solid electrolyte membranes is tortuous, which is not conducive to the rapid transport of lithium ions. Compared with the introduction of a three-dimensional network structure into polymers, the use of inorganic separation membranes can greatly improve the mechanical strength of polymer solid electrolyte membranes. However, inorganic separation membranes have poor flexibility and are prone to cracks or even breakage during actual use, resulting in a sharp drop in the mechanical strength of polymer solid electrolyte membranes and affecting the stable cycling of the battery. Summary of the Invention

[0004] This invention provides a polymer solid electrolyte membrane that simultaneously possesses high mechanical strength, good flexibility, and high ionic conductivity.

[0005] The present invention also provides a method for preparing a polymer solid electrolyte membrane. This method uses in-situ polymerization to automatically fill the pores of the inorganic separation membrane skeleton with polymer electrolyte without the need for additional energy. This method ensures the ionic conductivity of the polymer electrolyte while simplifying the preparation process.

[0006] The present invention also provides a solid-state battery, which, since it includes the above-mentioned polymer solid electrolyte membrane, has the advantages of low impedance and high cycle stability compared to conventional solid-state batteries.

[0007] The present invention also provides a battery pack, which, since it includes the above-mentioned solid-state battery, has the advantages of long cycle life and good rate performance.

[0008] The present invention also provides an electrical device that, since includes the above-mentioned solid-state battery or battery pack, has good electrical performance and a long service life.

[0009] In detail, in a first aspect, the present invention provides a polymer solid electrolyte membrane, comprising an inorganic separation membrane framework, the inorganic separation membrane framework comprising a plurality of through holes; at least a portion of the through holes are filled with a first polymer electrolyte and a first lithium salt, wherein the crystallinity of the first polymer electrolyte is not greater than 30%.

[0010] Furthermore, the crystallinity of the first polymer electrolyte is 10%-30%.

[0011] Furthermore, the diameter of the through-hole is 80nm-300nm; and / or, the porosity of the through-hole in the inorganic separation membrane skeleton is 20%-50%.

[0012] Furthermore, the first lithium salt accounts for 30%-70% of the mass of the first polymer electrolyte.

[0013] Furthermore, the inorganic separation membrane skeleton also includes several microcracks, at least a portion of which are filled with the first polymer electrolyte and the first lithium salt.

[0014] Furthermore, the depth of the microcrack is less than the thickness of the inorganic separation membrane skeleton; and / or, the width of the microcrack is less than 50 nm.

[0015] Furthermore, the inorganic separation membrane skeleton is made of metal oxides, metal alloys, or silicon oxide.

[0016] Furthermore, the thickness of the polymer solid electrolyte membrane is 15μm-50μm.

[0017] Furthermore, the two main surfaces of the inorganic separation membrane skeleton are respectively covered with a first transition layer and a second transition layer; the first transition layer contains a second polymer electrolyte and a second lithium salt; the second transition layer contains a second polymer electrolyte and a second lithium salt.

[0018] Further, the thickness of the first transition layer is 0.5 μm-10 μm; and / or, the thickness of the second transition layer is 0.5 μm-10 μm; and / or, the thickness of the inorganic separation membrane skeleton is 5 μm-40 μm.

[0019] Furthermore, at least a portion of the surface of the through-hole and / or the microcrack has a bonding relationship with the first polymer electrolyte.

[0020] Furthermore, the polymer structures of the first polymer electrolyte and the second polymer electrolyte contain (CH2CH2O). m , where m is an integer greater than 1.

[0021] Furthermore, the first polymer electrolyte and the second polymer electrolyte are polymerized from polymer monomers, wherein the polymer monomers have a structure as shown in Formula 1:

[0022]

[0023] In Equation 1, n≥1; R1 is

[0024] R3 is a C1-C5 alkyl group, R4 is a C1-C5 carbon chain, R5 is a C1-C5 alkyl group, R6 is a C1-C5 carbon chain; R2 is a mercapto, amino, hydroxyl, or carboxyl group.

[0025] One of them, R7 is a C1-C5 carbon chain, R8 is a C1-C5 alkyl group, and R9 is a C1-C5 carbon chain.

[0026] Furthermore, the polymer monomer is polyethylene glycol diglycidyl ether and / or polyethylene glycol dimethacrylate.

[0027] Furthermore, the molecular weight of the polymer monomer is 100 g / mol to 30000 g / mol.

[0028] Secondly, the present invention provides a method for preparing a polymer solid electrolyte membrane, comprising the following steps:

[0029] 1) The inorganic separation membrane skeleton is sequentially subjected to hydroxylation treatment and hydrophobic treatment with silane coupling agent; the treated inorganic separation membrane skeleton is then contacted with a mixed solution containing polymer monomers, catalysts and lithium salts to carry out a polymerization reaction, and a polymer solid electrolyte membrane precursor is obtained after the reaction.

[0030] 2) Apply external force to the polymer solid electrolyte membrane precursor to form several microcracks in the inorganic separation membrane skeleton, and then perform hot rolling treatment to obtain the polymer solid electrolyte membrane.

[0031] Furthermore, the silane coupling agent includes one or more of acrylic silane coupling agents, epoxy silane coupling agents, amino silane coupling agents, and mercapto silane coupling agents.

[0032] Thirdly, the present invention provides a solid-state battery comprising the polymer solid-state electrolyte membrane described in the first aspect.

[0033] Fourthly, the present invention provides a battery pack comprising the solid-state battery described in the third aspect.

[0034] In a sixth aspect, the present invention provides an electrical device comprising the solid-state battery described in the third aspect or the battery pack described in the fourth aspect.

[0035] The polymer solid electrolyte membrane provided by this invention has high mechanical strength due to the use of an inorganic separation membrane as a framework, which can avoid short circuits caused by lithium dendrite puncture. Furthermore, the inorganic separation membrane framework also includes through holes filled with a low-crystallinity first polymer electrolyte. The through holes construct a transport path for lithium ions perpendicular to the electrode, which can realize the rapid transport of lithium ions. The low-crystallinity polymer electrolyte can further increase the complexation sites of lithium ions, thereby further improving the lithium ion transport efficiency. Attached Figure Description

[0036] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0037] Figure 1 This is a schematic diagram of the structure of a polymer solid electrolyte membrane according to a specific embodiment of the present invention;

[0038] In the figure, 001: inorganic separation membrane skeleton, 002: through pores, 003: microcracks;

[0039] Figure 2 This is a schematic diagram of the structure of a polymer solid electrolyte membrane according to a specific embodiment of the present invention;

[0040] In the figure, 001: inorganic separation membrane skeleton, 004: first transition layer, 005: second transition layer. Detailed Implementation

[0041] To enable those skilled in the art to better understand the present invention, the present invention will be further described in detail below. The specific embodiments listed below are merely descriptions of the principles and features of the present invention, and the examples are only for explaining the present invention and are not intended to limit the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0042] In a first aspect, the present invention provides a polymer solid electrolyte membrane, combined with Figure 1 An inorganic separation membrane framework 001 includes a plurality of through holes 002, at least a portion of which are filled with a first polymer electrolyte and a first lithium salt; the crystallinity of the first polymer electrolyte is not greater than 30%.

[0043] In this invention, by defining the structure and composition of the polymer solid electrolyte membrane, it can possess high mechanical strength, good flexibility, and high ionic conductivity. This is because: the inorganic separation membrane acts as a framework, ensuring the overall mechanical strength of the polymer solid electrolyte membrane; the through-holes in the inorganic separation membrane framework, filled with a first polymer electrolyte, impart flexibility to the polymer solid electrolyte membrane, preventing excessive mechanical strength of the inorganic separation membrane framework from affecting normal use later. In addition, the through-holes in the inorganic separation membrane framework also construct a transport path for lithium ions perpendicular to the electrode, enabling rapid lithium ion transport; and the first polymer electrolyte, with its low crystallinity, increases the complexation sites for lithium ions, working synergistically with the through-holes to further improve lithium ion transport efficiency.

[0044] It should be noted that the through-holes involved in this invention refer to through-holes that extend linearly along the thickness direction of the inorganic separation membrane skeleton without changing the direction of extension. Regarding whether the diameters of the through-holes are consistent along the extension direction, this invention does not impose any particular limitation, but to maintain rapid and uniform lithium ion transport, it is preferable that the diameters of the through-holes are consistent along the extension direction.

[0045] In one alternative embodiment, the crystallinity of the first polymer electrolyte is 10%-30%.

[0046] For example, the crystallinity of the first polymer electrolyte is any one of 10%, 13%, 15%, 17%, 19%, 20%, 22%, 25%, 27%, 30%, etc.

[0047] In one optional embodiment, the diameter of the through-hole is 80nm-300nm, and / or the porosity of the through-hole in the inorganic separation membrane skeleton is 20%-50%.

[0048] The above-described embodiments limit the pore size and porosity of the through holes to ensure the proportion of the first polymer electrolyte in the inorganic separation membrane skeleton, thereby ensuring the rapid transport of lithium ions and avoiding excessively high or low local lithium ion counts, thus achieving rapid and uniform lithium ion transport in the polymer solid electrolyte membrane.

[0049] The mass ratio of the first polymer electrolyte to the first lithium salt can be adjusted according to the required conductivity. In order to ensure the conductivity and mechanical strength of the polymer solid electrolyte membrane, in an optional embodiment, the first lithium salt accounts for 30%-70% of the mass ratio of the first polymer electrolyte.

[0050] For example, the diameter of the through-hole is any value among 85nm, 90nm, 95nm, 100nm, 150nm, 170nm, 190nm, 200nm, 220nm, 250nm, 270nm, 290nm, etc., and the porosity of the through-hole of the inorganic separation membrane skeleton is any value among 25%, 30%, 35%, 40%, 45%, etc.

[0051] In an optional embodiment, the inorganic separation membrane skeleton further includes a plurality of microcracks 003, at least a portion of which are filled with the first polymer electrolyte and the first lithium salt.

[0052] The microcracks can further enhance the flexibility of the polymer solid electrolyte membrane, avoiding the impact on the normal use of the battery due to excessive mechanical strength of the inorganic separation membrane skeleton. Since the size of the microcracks also has a certain impact on the vertical transport path of lithium ions, in order to further improve the transport of lithium ions, in an optional embodiment, the depth of the microcracks is less than the thickness of the inorganic separation membrane skeleton; and / or, the width of the microcracks is less than 50 nm.

[0053] It can be understood that the thickness of the inorganic separation membrane skeleton is n, and the depth of the microcrack is m, where m is less than n.

[0054] For example, the width of the microcrack is in any range of 0.5-10nm, 1-20nm, 1-15nm, 2-30nm, 2-15nm, 2-20nm, 3-20nm, 3-17nm, 4-45nm, 4-10nm, 4-15nm, 4-20nm, 5-10nm, 5-15nm, 5-20nm, 5-30nm, etc.

[0055] In one optional embodiment, the inorganic separation membrane framework is made of aluminum alloy, alumina, or silicon oxide. The inorganic separation membrane framework made of these materials has a high dielectric constant, which can promote the dissociation of lithium salts, increase the number of transportable lithium ions, and thus contribute to the battery's capacity utilization.

[0056] For example, the inorganic separation membrane skeleton is made of aluminum alloy or aluminum oxide.

[0057] Thinner polymer solid electrolyte membranes can reduce resistance and increase conductivity, but may sacrifice mechanical strength and durability. Thicker polymer solid electrolyte membranes provide better mechanical strength and durability, but may increase resistance. Therefore, in order to balance the mechanical strength, durability and resistance of polymer solid electrolyte membranes, in an optional embodiment, the thickness of the polymer solid electrolyte membrane is 15μm-50μm.

[0058] For example, the thickness of the polymer solid electrolyte membrane is any value among 17μm, 20μm, 22μm, 25μm, 27μm, 30μm, 32μm, 35μm, 37μm, 40μm, 42μm, 45μm, 47μm, etc.

[0059] In one alternative implementation, combined with Figure 2 The inorganic separation membrane skeleton 001 further includes a first transition layer 004 and a second transition layer 005 on two sides in the thickness direction. The first transition layer 004 and the second transition layer 005 include a second polymer electrolyte and a second lithium salt.

[0060] In this embodiment, the first transition layer and the second transition layer are close to the positive and negative electrode sheets, respectively, and the second polymer electrolyte contained therein can play a transition role, thereby reducing the interfacial impedance between the polymer solid electrolyte membrane and the positive and negative electrodes.

[0061] It should be noted that the above-mentioned first transition layer and second transition layer are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the first transition layer and the second transition layer must have a specific order or orientation. Therefore, the appendix... Figure 2 The positional relationships included are for illustrative purposes only and should not be construed as limiting the present invention. In other words, the present invention can be satisfied as long as the first transition layer and the second transition layer are respectively disposed on two surfaces in the thickness direction of the inorganic separation membrane skeleton.

[0062] The first and second lithium salts mentioned above can be the same or different, and are generally selected from any one or more of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium bis(trifluoromethanesulfonamide)imide, lithium bis(fluorosulfonamide)imide, lithium bis(oxalate)borate, and lithium difluorooxalateborate.

[0063] The crystallinity of the second polymer electrolyte is not particularly limited in this invention, but in order to further improve the lithium ion transport efficiency, its crystallinity is preferably 10%-30%.

[0064] In one optional embodiment, the thickness of the first transition layer is 0.5 μm-10 μm, and / or the thickness of the second transition layer is 0.5 μm-10 μm; and / or the thickness of the inorganic separation membrane skeleton is 5 μm-40 μm.

[0065] The thickness of the first transition layer and / or the second transition layer is in the range of 0.5μm-10μm, which can further reduce the interfacial impedance between the polymer solid electrolyte membrane and the positive and negative electrodes while ensuring the lithium ion transport speed. The thickness of the inorganic separation membrane skeleton is 5-40μm, which enables the polymer solid electrolyte membrane to have high mechanical strength, durability and faster lithium ion transport performance.

[0066] For example, the thickness of the first transition layer and / or the second transition layer is any value selected from 0.7μm, 1μm, 1.5μm, 2μm, 2.5μm, 3μm, 3.5μm, 4μm, 4.5μm, 5μm, 5.5μm, 6μm, 6.5μm, 7μm, 7.5μm, 8μm, 8.5μm, 9μm, 9.5μm, etc.; and the thickness of the inorganic separation membrane skeleton is any value selected from 7μm, 10μm, 15μm, 17μm, 20μm, 22μm, 25μm, 27μm, 30μm, 35μm, 37μm, etc.

[0067] In one optional embodiment, at least a portion of the surface of the through-hole and / or the microcrack has a bonding relationship with the first polymeric electrolyte. In a specific embodiment, the bonding relationship between at least a portion of the surface of the through-hole and the first polymeric electrolyte, and the bonding relationship between at least a portion of the surface of the microcrack and the first polymeric electrolyte, facilitates the construction of a continuous ion transport pathway and can improve the stability of the first polymeric electrolyte; furthermore, when there is a bonding relationship between the through-hole and at least a portion of the surface of the microcrack and the first polymeric electrolyte, the polymer can flow more easily during the hot rolling process to achieve crack repair and filling.

[0068] It is understood that the bonding between the through-hole and at least part of the surface of the microcrack and the first polymer electrolyte can make the inorganic separation membrane skeleton and the polymer electrolyte more tightly bonded. As for the type of the above-mentioned bonding, the present invention does not make specific limitations. Those skilled in the art can select according to the structure of the first polymer electrolyte itself, such as including but not limited to: secondary amine bonding, thioether bonding or ether bonding.

[0069] For example, the above-mentioned bonding can be determined by infrared analysis.

[0070] In an optional embodiment, the polymer structures of the first and second polymer electrolytes contain (CH2CH2O). m , where m is an integer greater than 1.

[0071] To further improve ion transport in the polymer solid electrolyte membrane, in an optional embodiment, the first and second polymer electrolytes are polymerized from polymer monomers having a structure as shown in Formula 1:

[0072]

[0073] In Equation 1, n≥1; R1 is

[0074] R3 is a C1-C5 alkyl group, R4 is a C1-C5 carbon chain, R5 is a C1-C5 alkyl group, R6 is a C1-C5 carbon chain; R2 is a mercapto, amino, hydroxyl, or carboxyl group.

[0075] One of them, R7 is a C1-C5 carbon chain, R8 is a C1-C5 alkyl group, and R9 is a C1-C5 carbon chain.

[0076] In one optional embodiment, the molecular weight of the polymer monomer is 100-30000 g / mol. The molecular weight of the polymer monomer is related to the viscosity of the polymer monomer solution; higher molecular weight results in higher viscosity, poorer capillary filling rate and effect, leading to higher crystallinity of the first polymer electrolyte and affecting the lithium-ion transport efficiency of the polymer solid electrolyte membrane. Simultaneously, the molecular weight of the polymer monomer is also related to the polymerization rate; lower molecular weight results in higher reactivity, faster polymerization rate, and lower reaction controllability. Therefore, low molecular weight monomers tend to form low molecular weight polymers, and high molecular weight monomers tend to form high molecular weight polymers.

[0077] In one specific implementation, n is any value from 5 to 200.

[0078] In one specific embodiment, the polymer monomer is polyethylene glycol diglycidyl ether and / or polyethylene glycol dimethacrylate.

[0079] To further ensure the flexibility of the polymer solid electrolyte membrane, in one specific embodiment, the molecular weight of the first polymer electrolyte is below 600,000 g / mol, and the molecular weight of the second polymer electrolyte is below 600,000 g / mol.

[0080] Secondly, the present invention provides a method for preparing a polymer solid electrolyte membrane, comprising the following steps:

[0081] 1) The inorganic separation membrane skeleton is sequentially subjected to hydroxylation treatment and hydrophobic treatment with silane coupling agent; the treated inorganic separation membrane skeleton is then contacted with a mixed solution containing polymer monomers, catalysts and lithium salts to carry out a polymerization reaction, and a polymer solid electrolyte membrane precursor is obtained after the reaction.

[0082] 2) Apply external force to the polymer solid electrolyte membrane precursor to form several microcracks in the inorganic separation membrane skeleton, and then perform hot rolling treatment to obtain the polymer solid electrolyte membrane.

[0083] In the above preparation method, in step 1), after the inorganic separation membrane skeleton is hydroxylated, its surface and pores contain a large number of hydroxyl groups, which provide a large number of binding sites for the silane coupling agent. Subsequently, the inorganic separation membrane treated with the silane coupling agent has good oleophilic and hydrophobic properties, which helps the mixed solution containing polymer monomers to enter the pores. During the polymerization of polymer monomers, due to the nano-confined effect of the pores and the high dielectric constant of the inorganic separation membrane, the crystallinity of the polymer is greatly reduced, and finally a polymer solid electrolyte membrane precursor is prepared. The precursor differs from the target polymer solid electrolyte membrane only in the presence of microcracks. Therefore, in step 2), an external force is applied to the polymer solid electrolyte membrane precursor to form several microcracks. Subsequently, during the hot rolling process, the polymer in the pores melts and fills the microcracks. In addition, after hot rolling, a certain thickness of polymer electrolyte remains on the upper and lower surfaces of the inorganic separation membrane skeleton. This layer structure is the first transition layer and the second transition layer. The combination of the two can greatly reduce the interfacial impedance between the polymer solid electrolyte membrane and the positive and negative electrodes.

[0084] The present invention does not impose any particular limitation on the operation of applying external force as described above, as long as it does not damage the overall structure of the inorganic separation membrane skeleton while forming several microcracks. For example, the polymer solid electrolyte membrane precursor is bent at any angle between 90° and 180° on a round rod.

[0085] The silane coupling agent described above only needs to be able to combine with hydroxyl groups and make the inorganic separation membrane skeleton hydrophobic. The specific type is not particularly limited in this invention. In one specific embodiment, the silane coupling agent is selected from one or more of acrylic silane coupling agents, epoxy silane coupling agents, amino silane coupling agents, and mercapto silane coupling agents. The silane coupling agent in this embodiment not only functions to hydrophobize but also participates in the polymerization of polymer monomers, making the bond between the polymer electrolyte and the inorganic separation membrane skeleton more stable.

[0086] For example, the catalyst includes, but is not limited to, alkanolamine catalysts, diamide catalysts, etc.

[0087] In one embodiment, when the polymer monomer includes unsaturated C-C double bonds, the mixed solution in step 1) further contains an initiator, which includes, but is not limited to, azo initiators, peroxide initiators, etc.

[0088] For example, the lithium salts include, but are not limited to, any one or more of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium bis(trifluoromethanesulfonamide)imide, lithium bis(fluorosulfonamide)imide, lithium bis(oxalateborate)borate, and lithium difluorooxalateborate.

[0089] It is understood that the temperature and time of the polymerization reaction can be adjusted according to the desired degree of polymerization and the molecular weight of the first and second polymer electrolytes. For example, the polymerization reaction is carried out under vacuum conditions at 70-90°C for 2-5 hours.

[0090] The ratio of the polymer monomer, catalyst, initiator and lithium salt can be adjusted according to the degree of polymerization, the molecular weight and conductivity of the first polymer electrolyte and the second polymer electrolyte. For example, the catalyst accounts for no more than 2% of the polymer monomer by mass and the initiator accounts for no more than 2% of the polymer monomer by mass.

[0091] Thirdly, the present invention provides a solid-state battery comprising the polymer solid-state electrolyte membrane described in the first aspect.

[0092] It is understood that the solid-state battery also includes a positive electrode and a negative electrode. In an optional embodiment, the negative electrode includes a current collector and a negative electrode coating disposed on the current collector; the positive electrode includes a current collector and a positive electrode coating disposed on the current collector.

[0093] The aforementioned negative electrode coating also includes negative electrode active particles and optionally a binder. The negative electrode active particles are various lithium-intercalation / deintercalation-capable negative electrode active materials commonly used by those skilled in the art. For example, they can be selected from one or more of carbon materials, tin alloys, silicon alloys, silicon, tin, and germanium, and can also be metallic lithium, lithium-indium alloys, etc. The carbon material can be one or more of non-graphitized carbon, graphite, or carbon or pyrolytic carbon, coke, sintered organic polymers, activated carbon, etc., obtained by high-temperature oxidation of polyyne-based polymers. When the negative electrode active particles are silicon-based materials... Furthermore, the negative electrode coating also contains a conductive agent, which is a material commonly used by those skilled in the art to enhance electron transport. For example, it can be selected from at least one of natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fiber, carbon nanotubes, metal powder, graphene, etc.; the binder can be selected from at least one of polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polytetrafluoroethylene, polyacrylonitrile, polypropylene carbonate, styrene-butadiene rubber, nitrile rubber, sodium carboxymethyl cellulose, polyethylene oxide, ethylene oxide-propylene oxide copolymer.

[0094] Similarly, the above-mentioned positive electrode coating also includes positive electrode active particles, a conductive agent, and optionally a binder, wherein the positive electrode active particles are selected from lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), lithium iron phosphate (LiFePO4), lithium cobalt phosphate (LiCoPO4), lithium manganese phosphate (LiMnPO4), lithium nickel phosphate (LiNiPO4), lithium manganese oxide (LiMnO2), and binary materials LiNi x A (1-x)O2 (where A is selected from one of Co and Mn, 0 < x < 1), ternary material LiNimBnC (1-m-n) O2 (where B and C are independently selected from at least one of Co, Al, and Mn, and B and C are different, 0 < m < 1, 0 < n < 1)); the conductive agent is a material commonly used by those skilled in the art that can enhance electron transfer, for example, it can be selected from at least one of natural graphite, artificial graphite, carbon black, acetylene black, Super P, Super S, graphene, carbon fiber, carbon nanotube, and Ketjen black, etc.; the binder can be selected from at least one of polyvinylidene fluoride, vinylidene fluoride - hexafluoropropylene copolymer, polytetrafluoroethylene, polyacrylonitrile, polycarbonate propylene, styrene - butadiene rubber, nitrile rubber, sodium carboxymethyl cellulose, polyethylene oxide, ethylene oxide - propylene oxide copolymer, polyethylene, polypropylene, polyamideimide, polyvinyl alcohol, and sodium polyacrylate.

[0095] To ensure the capacity of the solid - state battery is exerted, exemplarily, the mass ratio of the positive - electrode active particles to the positive - electrode coating is 50% - 90%.

[0096] Regarding the particle - size distribution of the above - mentioned positive - electrode active particles and negative - electrode active particles, the present invention does not make specific limitations. For example, the D50 of the above - mentioned positive - electrode active particles or negative - electrode active particles can be 5 - 16 μm, specifically including but not limited to: 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, etc.; the D99 can be 14 - 30 μm, specifically including but not limited to: 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, 20 μm, 21 μm, 22 μm, 23 μm, 24 μm, 25 μm, 26 μm, 27 μm, 28 μm, 29 μm, etc.; the D10 can be 2 - 10 μm, specifically including but not limited to: 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, etc.

[0097] Regarding the thickness and surface density of the above - mentioned positive - electrode sheet and negative - electrode sheet, the present invention does not make specific limitations. However, in order to balance the battery capacity, cycle life, and energy density, in a specific embodiment, the thickness of the positive - electrode sheet or negative - electrode sheet is 40 - 120 μm, specifically including but not limited to: 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, 110 μm, etc.; the surface density of the positive - electrode sheet or negative - electrode sheet is 3 - 10 mg / cm 2 , specifically including but not limited to: 3.5 mg / cm 2 、4 mg / cm 2 、4.5 mg / cm 2 、5 mg / cm 2 、5.5 mg / cm 2 、6 mg / cm2 6.5 mg / cm 2 7mg / cm 2 7.5 mg / cm 2 8mg / cm 2 8.5 mg / cm 2 9mg / cm 2 9.5 mg / cm 2 wait.

[0098] The above-mentioned solid-state battery fabrication method can employ any conventional process. For example, the fabrication of a solid-state battery includes: placing an electrolyte layer between a positive electrode and a negative electrode, welding tabs onto the positive and negative electrode sheets, stacking them, and sealing them in an aluminum-plastic film. The positive electrode fabrication method may include: providing an electrode slurry containing positive active particles and a conductive agent; coating the electrode slurry onto an electrode current collector and drying it to form a positive electrode coating. The negative electrode fabrication method may include: providing an electrode slurry containing negative active particles and a conductive agent; coating the electrode slurry onto an electrode current collector and drying it to form a positive electrode coating.

[0099] The solid-state battery of the present invention does not have any particular limitation on the current collector. Conventional electrode current collectors in the art can be used, such as copper foil, aluminum foil, etc., and their thickness can be, for example, 1-100 μm.

[0100] It should be noted that the above-mentioned solid-state battery may include, but is not limited to, single cell, battery module, battery pack, etc. That is, the actual application form of the battery provided by the present invention may be, but is not limited to, the listed products, or other application forms. When the battery is a single cell, it includes at least one of cylindrical battery, prismatic battery, etc.

[0101] Fourthly, the present invention provides a battery pack comprising the solid-state battery described in the third aspect.

[0102] Fifthly, the present invention provides an electrical device comprising the solid-state battery described in the third aspect or the battery pack described in the fourth aspect.

[0103] It should be noted that the aforementioned electronic devices can be any conventional device that requires electricity, such as, but not limited to, computers, electric vehicles, air conditioners, refrigerators, washing machines, microwave ovens, printers, fax machines, etc.

[0104] The present invention will be further described below with reference to specific embodiments:

[0105] Example 1

[0106] This example provides a polymer solid electrolyte membrane, combined with... Figure 1 and Figure 2The membrane includes a first transition layer 004, a second transition layer 005, and an intermediate inorganic separation membrane framework 001. The inorganic separation membrane framework includes several through holes 002 and several microcracks 003. At least some of the through holes and microcracks are filled with a first polymer electrolyte and lithium bis(trifluoromethanesulfonyl)imide. The first and second transition layers include a second polymer electrolyte and lithium bis(trifluoromethanesulfonyl)imide. The crystallinity of the first polymer electrolyte is 26.3%. The crystallinity of the second polymer electrolyte is greater than 30%.

[0107] The inorganic separation membrane framework is an aluminum alloy anodic oxide film; the depth of the microcracks is less than 40 μm and the width is 50-70 nm; the thickness of the first transition layer is 2.5 μm, the thickness of the second transition layer is 2.5 μm, and the thickness of the intermediate inorganic separation membrane framework 001 is 40 μm; the diameter of the through-hole is 200 nm, and the porosity of the aluminum alloy anodic oxide film is 25%; the first lithium salt accounts for 60% of the mass of the first polymer electrolyte.

[0108] The preparation of the above-mentioned polymer solid electrolyte membrane includes the following steps:

[0109] 1) The aluminum alloy anodic oxide film with a pore size of 200 nm, a thickness of 40 μm, and a porosity of 25% was rinsed 5 times with ultrapure water to remove residual acid and other impurities on the surface. Then, the oxide film was placed in hot water at 90℃ for 10 min for hydroxylation treatment to obtain a hydroxylated oxide film. The silane coupling agent KH560 solution, ultrapure water and methanol solution were mixed and the pH value was adjusted to 7 with glacial acetic acid. After the silane coupling agent was completely hydrolyzed, the hydroxylated oxide film was placed in the solution and immersed for a period of time. After that, the aluminum alloy anodic oxide film was taken out and the residual liquid on the surface of the aluminum alloy anodic oxide film was dried with cold air. After cross-linking and curing in a drying oven, the modified aluminum alloy anodic oxide film was obtained.

[0110] 2) Mix polyethylene glycol diglycidyl ether, N,N-dimethylethanolamine and lithium bis(trifluoromethanesulfonyl)imide with a molecular weight of 10000 g / mol until homogeneous (wherein, the mass ratio of polyethylene glycol diglycidyl ether to lithium bis(trifluoromethanesulfonyl)imide is 1:0.6, and the molar ratio of polyethylene glycol diglycidyl ether to N,N-dimethylethanolamine is 1:0.01). Then pour the solution into a tray containing a modified aluminum alloy anodized film, place the tray in a 90℃ vacuum oven, and remove the polymer solid electrolyte film after 3 hours.

[0111] 3) The polymer solid electrolyte membrane precursor is bent on a round bar with a diameter of 10 mm, and then rolled at 100°C on a hot roll press with a fixed slit of 45 μm to obtain the polymer solid electrolyte membrane.

[0112] Example 2

[0113] This example provides a polymer solid electrolyte membrane, which differs from Example 1 in that: the through-hole diameter of the aluminum alloy anodic oxide membrane used is 80 nm, the membrane thickness is 40 μm, the porosity is 40%, and the crystallinity of the first polymer electrolyte is 25.5%.

[0114] The preparation method is the same as in Example 1, except that: the silane coupling agent is KH570, the monomer is polyethylene glycol dimethacrylate with a molecular weight of 10000 g / mol, and the initiator is azobisisobutyronitrile (AIBN).

[0115] Example 3

[0116] This example provides a polymer solid electrolyte membrane, which differs from Example 1 in that the crystallinity of the first polymer electrolyte is 17.5%.

[0117] The preparation method is the same as in Example 2, except that the silane coupling agent is KH560 and the monomer is polyethylene glycol diglycidyl ether with a molecular weight of 1000 g / mol.

[0118] Example 4

[0119] This example provides a polymer solid electrolyte membrane, which differs from Example 2 in that: the crystallinity of the first polymer electrolyte is 24.9%, and the through-pore diameter of the aluminum alloy anodic oxide film is 80 nm, the film thickness is 20 μm, and the porosity is 40%.

[0120] The preparation method is the same as in Example 2, except that the monomer is polyethylene glycol diglycidyl ether with a molecular weight of 10000 g / mol.

[0121] Example 5

[0122] This example provides a polymer solid electrolyte membrane, which differs from Example 1 in that the crystallinity of the first polymer electrolyte is 22.8%.

[0123] The preparation method is the same as in Example 1, except that: the monomer is polyethylene glycol dimethacrylate with a molecular weight of 1000 g / mol; and the initiator is azobisisobutyronitrile (AIBN).

[0124] Example 6

[0125] This example provides a polymer solid electrolyte membrane, which differs from Example 1 in that the crystallinity of the first polymer electrolyte is 20.3%, and the thickness of the intermediate inorganic separation membrane skeleton is 20 μm.

[0126] The preparation method is the same as in Example 1, except that the thickness of the aluminum alloy anodic oxide film used is 20 μm; the silane coupling agent is KH570; and the monomer is polyethylene glycol diglycidyl ether with a molecular weight of 1000 g / mol.

[0127] Example 7

[0128] This example provides a polymer solid electrolyte membrane, which differs from Example 1 in that: the crystallinity of the first polymer electrolyte is 18.3%, the through-pore diameter of the aluminum alloy anodic oxide film is 80 nm, the film thickness is 20 μm, and the porosity is 40%.

[0129] The preparation method is the same as in Example 1, except that the silane coupling agent is KH560 and the monomer is polyethylene glycol dimethacrylate with a molecular weight of 1000 g / mol.

[0130] Example 8

[0131] This example provides a polymer solid electrolyte membrane. Unlike Example 1, the first polymer electrolyte has a crystallinity of 27.4%, and the thickness of the aluminum alloy anodic oxide film used is 20 μm.

[0132] The preparation method is the same as in Example 1, except that the silane coupling agent is KH560 and the monomer is polyethylene glycol dimethacrylate with a molecular weight of 10000 g / mol.

[0133] Example 9

[0134] This example provides a polymer solid electrolyte membrane, which differs from Example 1 in that: the crystallinity of the first polymer electrolyte is 28.9%, and the pore size of the through-holes in the aluminum alloy anodic oxide film is 300 nm.

[0135] Example 10

[0136] This example provides a polymer solid electrolyte membrane, which differs from Example 1 in that the crystallinity of the first polymer electrolyte is 29.7%, and the width of the microcracks is 100-120 nm.

[0137] The preparation method is the same as in Example 1, except that the bending angle is increased.

[0138] Example 11

[0139] This example provides a polymer solid electrolyte membrane, which differs from Example 1 in that: the crystallinity of the first polymer electrolyte is 28.2%, and the inorganic separation membrane framework is silicon oxide.

[0140] Example 12

[0141] This example provides a polymer solid electrolyte membrane, which differs from Example 1 in that: the crystallinity of the polymer electrolyte is shown in Table 1, the inorganic separation membrane skeleton does not include microcracks, and its preparation method is the same as in Example 1, except that: the polymer solid electrolyte membrane precursor is not bent on a round bar, but directly rolled.

[0142] Comparative Example 1

[0143] This example provides a polymer solid electrolyte membrane, which differs from Example 1 in that the polymer electrolyte has a crystallinity of 32.7%, no microcracks, and no first or second transition layer.

[0144] Its preparation method includes the following steps:

[0145] Polyethylene oxide (PEO) with a molecular weight of 600,000 g / mol and lithium bis(trifluoromethanesulfonyl)imide were dissolved in anhydrous acetonitrile at a mass ratio of 1:0.673 and stirred until homogeneous. The solution was then poured into a polytetrafluoroethylene mold and the solvent was dried at 60 °C to obtain a polymer electrolyte. This polymer electrolyte was placed on the surface of an aluminum alloy anodic oxide film with a pore size of 200 nm, a film thickness of 40 μm, and a porosity of 25%, and placed in a vacuum environment at 180 °C for 24 hours. Finally, the polymer electrolyte on both surfaces of the aluminum alloy anodic oxide film in the thickness direction was scraped off to obtain a polymer solid electrolyte film.

[0146] Comparative Example 2

[0147] This example provides a polymer solid electrolyte membrane. Unlike Comparative Example 1, the polymer electrolyte has a crystallinity of 33% and includes a first transition layer and a second transition layer. The preparation method is the same as that of Comparative Example 1, except that the excess polymer electrolyte on the surface of the aluminum alloy anodized film is not scraped off, and finally, it is rolled at 100°C on a hot roll press with a fixed slit of 45 μm, so that the thickness of the polymer electrolyte on the upper and lower surfaces of the aluminum alloy anodized film is 2.5 μm.

[0148] Comparative Example 3

[0149] This example provides a polymer solid electrolyte membrane. Unlike Example 1, the first polymer electrolyte has a crystallinity of 30.3%, and the oxide film used has a pore diameter of 200 nm, a thickness of 40 μm, and a porosity of 25%.

[0150] The preparation method is the same as in Example 1, except that it is not treated with a silane coupling agent and the molecular weight of the polyethylene glycol diglycidyl ether used is 30,000 g / mol.

[0151] Comparative Example 4

[0152] This example provides a polymer solid electrolyte membrane, which differs from Example 1 in that: the membrane skeleton is a three-dimensional polymer membrane prepared by electrospinning of PVDF solution, and it is not treated with silane coupling agent.

[0153] Application examples

[0154] The polymer solid electrolyte membranes of the above embodiments and comparative examples are used to assemble solid-state full cells, including the following processes:

[0155] 1. Preparation of blocking batteries

[0156] CR2025 coin cells were assembled in an argon-filled glove box (O2 ≤ 0.5 ppm, H2O ≤ 0.5 ppm), with 10 μm copper foil as electrodes and the above-mentioned polymer solid electrolyte membranes as electrolytes.

[0157] 2. Preparation of solid-state full cells

[0158] CR2025 coin cells were assembled in an argon-filled glove box (O2 ≤ 0.5 ppm, H2O ≤ 0.5 ppm). The positive electrode was a lithium iron phosphate electrode, composed of lithium iron phosphate, a conductive agent, and a binder in a mass ratio of 63:7:30. The negative electrode was a 25 μm thick lithium foil, and the electrolyte was the aforementioned polymer solid electrolyte membrane.

[0159] Related tests:

[0160] The crystallinity of the polymer solid electrolyte membranes obtained in each embodiment and comparative example was tested, the ionic conductivity of the blocked battery was tested, and the battery impedance and cycle life of the solid full cell were tested. The test results are shown in Table 1.

[0161] 1. Crystallinity Test Method for the First Polymer Electrolyte: For the DSC tests of the polymer solid-state electrolytes in each example and comparative example, the transition layer on the surface of the inorganic separation membrane was scraped off before testing. The first polymer electrolyte was tested using a Mettler Toledo instrument in a nitrogen atmosphere at a temperature range of 25℃-200℃ and a heating rate of 10℃ / min. The crystallinity was calculated as follows:

[0162]

[0163] Where ΔH m The enthalpy of fusion of the polymer solid electrolyte, ΔH M The standard enthalpy of pure crystalline PEO, f spe f represents the proportion of polymer in the polymer solid electrolyte, where f spe The calculation methods are as follows:

[0164]

[0165] Where d is the oxide film pore size (μm), D is the oxide film thickness (μm), and χ is the oxide film porosity.

[0166] 2. The ionic conductivity testing method is as follows: Ten blocking batteries prepared in each example and comparative example were taken and subjected to AC impedance testing in the frequency range of 10Hz to 300KHz at 25±1℃ using an Autolab PGSTAT 302N electrochemical workstation. After fitting the impedance spectrum, the intersection of the oblique line and the horizontal axis was taken as the bulk impedance of the electrolyte material. The ionic conductivity was calculated using the following formula:

[0167]

[0168] Where δ(S cm) -1 ) represents the ionic conductivity, L (cm) represents the thickness of the polymer solid electrolyte membrane, and S (cm) represents the thickness of the membrane. 2 R(Ω) represents the effective contact area between the polymer solid electrolyte membrane and the copper foil, and R(Ω) represents the intrinsic impedance.

[0169] 3. The battery impedance test method is as follows: Three full cells from each of the examples and comparative examples were taken and subjected to AC impedance testing at 25±1℃ on an Autolab PGSTAT 302N electrochemical workstation in a frequency range of 100mHz to 3MHz. After fitting the impedance spectrum, the intersection of the oblique line and the horizontal axis of the second semicircle was taken as the battery impedance.

[0170] 4. The cycle life test method is as follows: Take 10 batteries from each of the examples and comparative examples, and conduct a charge-discharge cycle test at 0.5C on a LAND CT 2001C secondary battery performance testing device at 25±1℃. The steps are as follows: rest for 5 minutes; constant current charging to 3.8V and then cut off; rest for 5 minutes; constant current discharging to 2.7V, which is one cycle. Repeat this step. During the cycle, when the battery capacity is lower than 80% of the initial discharge capacity, the cycle is terminated. The number of cycles is the cycle life of the battery.

[0171] 5. The test method for microcrack size is as follows: The polymer electrolytes containing microcracks in each embodiment and comparative example are immersed in acetonitrile solution, heated and kept at that temperature for 24 hours, and then rinsed with ethanol 5-6 times to fully wash away the polymer in the oxide film. After rinsing and drying, the oxide film is sputtered with gold and then tested using a scanning electron microscope. Tests are performed using a ZEISSSUPRA 40 at an accelerating voltage of 15KV. The number of cracks between pores is counted, and if the count is greater than 100, the average value is taken.

[0172] Table 1:

[0173]

[0174]

[0175] As shown in Table 1, compared with the comparative example, the polymer solid electrolyte membrane provided in the examples can be used in solid-state batteries with high ionic conductivity, long cycle life and low impedance.

[0176] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A polymer solid electrolyte membrane, characterized in that, The membrane includes an inorganic separation membrane framework, which includes a plurality of through-holes; at least a portion of the through-holes are filled with a first polymer electrolyte and a first lithium salt, wherein the crystallinity of the first polymer electrolyte is not greater than 30%.

2. The polymer solid electrolyte membrane according to claim 1, characterized in that, The crystallinity of the first polymer electrolyte is 10%-30%.

3. The polymer solid electrolyte membrane according to claim 1, characterized in that, The diameter of the through-hole is 80nm-300nm; and / or, the porosity of the through-hole in the inorganic separation membrane skeleton is 20%-50%.

4. The polymer solid electrolyte membrane according to claim 1, characterized in that, The first lithium salt accounts for 30%-70% of the mass of the first polymer electrolyte.

5. The polymer solid electrolyte membrane according to claim 1, characterized in that, The inorganic separation membrane skeleton also includes several microcracks, at least some of which are filled with the first polymer electrolyte and the first lithium salt.

6. The polymer solid electrolyte membrane according to claim 5, characterized in that, The depth of the microcrack is less than the thickness of the inorganic separation membrane skeleton; and / or, the width of the microcrack is less than 50 nm.

7. The polymer solid electrolyte membrane according to claim 5, characterized in that, At least a portion of the surface of the through-hole and / or the microcrack has a bonding relationship with the first polymer electrolyte.

8. The polymer solid electrolyte membrane according to claim 1, characterized in that, The inorganic separation membrane skeleton is made of metal oxides, metal alloys, or silicon oxide.

9. The polymer solid electrolyte membrane according to any one of claims 1-8, characterized in that, The thickness of the polymer solid electrolyte membrane is 15μm-50μm.

10. The polymer solid electrolyte membrane according to any one of claims 1-8, characterized in that, The two main surfaces of the inorganic separation membrane skeleton are respectively covered with a first transition layer and a second transition layer; the first transition layer contains a second polymer electrolyte and a second lithium salt; the second transition layer contains a second polymer electrolyte and a second lithium salt.

11. The polymer solid electrolyte membrane according to claim 10, characterized in that, The thickness of the first transition layer is 0.5 μm-10 μm; and / or, the thickness of the second transition layer is 0.5 μm-10 μm; and / or, the thickness of the inorganic separation membrane skeleton is 5 μm-40 μm.

12. The polymer solid electrolyte membrane according to claim 10, characterized in that, The polymer structures of the first and second polymer electrolytes contain (CH2CH2O). m , where m is an integer greater than 1.

13. The polymer solid electrolyte membrane according to claim 10, characterized in that, The first and second polymer electrolytes are polymerized from polymer monomers having a structure as shown in Formula 1: In Equation 1, n≥1; R1 is R3 is a C1-C5 alkyl group, R4 is a C1-C5 carbon chain, R5 is a C1-C5 alkyl group, R6 is a C1-C5 carbon chain; R2 is a mercapto, amino, hydroxyl, or carboxyl group. One of them, R7 is a C1-C5 carbon chain, R8 is a C1-C5 alkyl group, and R9 is a C1-C5 carbon chain.

14. The polymer solid electrolyte membrane according to claim 13, characterized in that, The polymer monomers are polyethylene glycol diglycidyl ether and / or polyethylene glycol dimethacrylate.

15. The polymer solid electrolyte membrane according to claim 13, characterized in that, The molecular weight of the polymer monomer is 100 g / mol to 30000 g / mol.

16. A method for preparing a polymer solid electrolyte membrane as described in any one of claims 1-15, characterized in that, Includes the following steps: 1) The inorganic separation membrane skeleton is sequentially subjected to hydroxylation treatment and hydrophobic treatment with silane coupling agent; the treated inorganic separation membrane skeleton is then contacted with a mixed solution containing polymer monomers, catalysts and lithium salts to carry out a polymerization reaction, and a polymer solid electrolyte membrane precursor is obtained after the reaction. 2) Apply external force to the polymer solid electrolyte membrane precursor to form several microcracks in the inorganic separation membrane skeleton, and then perform hot rolling treatment to obtain the polymer solid electrolyte membrane.

17. The preparation method according to claim 16, characterized in that, The silane coupling agent includes one or more of the following: acrylic silane coupling agents, epoxy silane coupling agents, amino silane coupling agents, and mercapto silane coupling agents.

18. A solid-state battery, comprising a positive electrode, a negative electrode, and a polymer solid electrolyte membrane as described in any one of claims 1-15.

19. A battery pack, characterized in that, Including the solid-state battery as described in claim 18.

20. An electrical appliance, characterized in that, Includes the solid-state battery of claim 18 or the battery pack of claim 19.

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