Interface modification layer construction method of Prussian blue electrode material

Abstract

The invention discloses an interface modification layer construction method of a Prussian blue electrode material, and the method comprises the following steps: step 1, preparing a Prussian blue positive electrode material into a positive electrode plate, and rolling the positive electrode plate; step 2, performing construction of an interface modification layer on the rolled positive pole piece through an atomic layer deposition or molecular layer deposition technology, wherein the interface modification layer is composed of one of an all-inorganic-organic / inorganic hybrid-all-organic interface modification layer, an all-organic-organic / inorganic hybrid-all-inorganic interface modification layer, an organic / inorganic hybrid-all-organic interface modification layer, an organic / inorganic hybrid-all-inorganic interface modification layer, an all-organic-all-inorganic interface modification layer and an all-inorganic-all-organic interface modification layer from the electrode side to the electrolyte side in sequence. According to the method, an artificial interface modification layer is constructed at the electrode scale, the components and thickness of the interface modification layer are regulated and controlled, and the cycle performance of the Prussian blue positive electrode material and the safety performance of the battery are improved.

Description

Technical Field

[0001] The invention belongs to the technical field of batteries and relates to a method for constructing an interface modification layer of a Prussian blue electrode material. Background Art

[0002] Prussian blue sodium cathode material is one of the most promising cathode materials for sodium ion batteries. However, its inevitable material defects and crystal water problems can cause strong interface side reactions. In addition, the complex phase change process during the charge and discharge process can also cause large stress accumulation, affecting the battery cycle performance and battery safety. At present, the modification is mainly carried out through material surface coating, electrode interface modification and addition of electrolyte additives.

[0003] Since Prussian blue materials are generally cubic block morphology, and the thermal stability of Prussian blue materials is general, it is difficult to stably and uniformly coat by conventional means such as coating by secondary calcination. Relative to coating means such as vapor deposition (CN117165914 A) and electrodeposition (CN 117776350A), atomic layer deposition or molecular layer deposition technology can achieve coating at the atomic or molecular scale, with the advantages of high accuracy, adjustable structure, good comformability, and wide operating temperature range. However, this technology is currently only used in the interface modification of layered transition metal oxide positive electrode materials (CN 117117134A, CN 117855420A) and electrodes thereof (CN115602786A), and has not yet been applied to Prussian blue positive electrode materials. Although the interface modification layer plays the same role in reducing interface side reactions and transition metal dissolution, the main reasons why this technology is less used in Prussian blue materials due to the intrinsic differences between the two materials are as follows: 1. Due to the poor thermal stability of Prussian blue materials, after interface modification at the material scale, it is difficult to perform subsequent secondary calcination like layered oxides (CN 117954608 A) to improve the crystallinity of the interface modification layer. 2. The failure mechanisms of the two positive electrode materials are different, and the use of the same all-inorganic modification layer (CN 107910518 A) as layered transition metal oxide materials may have a counter-effect. 3. The construction of a poor modification layer may cause the three-dimensional sodium ion diffusion channel of Prussian blue materials to be blocked, increasing battery polarization and affecting performance. 4. Prussian blue materials inevitably have crystal water, and the influence of electrolyte acidification needs to be considered when constructing the interface modification layer. 5. The phase change mechanism of Prussian blue materials is different from that of layered transition metal oxides, and the design of the interface modification layer needs to ensure its reversible phase change.

[0004] Therefore, how to construct an interface modification layer with good ionic and electronic conductivity, mechanical strength and elasticity, and resistance to hydrofluoric acid corrosion is a technical difficulty. Summary of the invention

[0005] In order to solve the problems existing in the background technology, the present invention provides a method for constructing an interface modification layer of a Prussian blue electrode material. The method constructs an artificial interface modification layer at the electrode scale, regulates the composition and thickness of the interface modification layer, and improves the cycle performance of the Prussian blue cathode material and the safety performance of the battery.

[0006] The objective of the present invention is achieved through the following technical solutions:

[0007] A method for constructing an interface modification layer of a Prussian blue electrode material comprises the following steps:

[0008] Step 1: Prepare the Prussian blue positive electrode material into a positive electrode sheet and roll-press it, wherein:

[0009] The positive electrode plate is composed of a Prussian blue active material, conductive carbon and a binder, wherein the mass fraction of the Prussian blue active material is 70-90%, the mass fraction of the conductive carbon is 6-20%, and the mass fraction of the binder is 4-10%;

[0010] The Prussian blue positive electrode material is prepared by a co-precipitation method, and can also be prepared by a hydrothermal method and a ball milling method;

[0011] The chemical formula of the Prussian blue positive electrode material is A x M[Fe(CN) 6 ] 1-y ·nH 2 O, where 0≤x≤2, 0≤y<1, 0<n≤3.5;

[0012] A includes one or more of Li, Na, K, Mg, Ca, and Zn. Preferably, the molar ratio of each metal element is Na:K=1:1, Na:K=3:1, and Na:K=4:1;

[0013] The M must include Mn and Fe elements, and other metal elements may also include one or a combination of Sc, Ti, V, Cr, Co, Ni, Cu, Zn, Ga, Y, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Cd, In, Sn, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm and Yb. Preferably, the molar ratio of each metal element is Mn:Fe=1:1, Mn:Fe=3:2, Mn:Fe:Ni=1:1:1, Mn:Fe:Ni=2:2:1, Mn:Fe:Co:Ni=1:1:1:1, Mn:Fe:Co:Ni=4:4:1:1, Mn:Fe:Co:Ni:Zn=1:1:1:1:1, Mn:Fe:Co:Ni:Cu:Zn=1:1:1:1:1:1;

[0014] The conductive carbon is one or more of superP, Ketjen black, carbon nanotubes and graphene;

[0015] The binder is one of PVDF, PTFE, sodium alginate and PAA;

[0016] The rolling pressure of the positive electrode sheet is 5-100 MPa, and the rolling time is 5s-5min. Preferably, the rolling pressure is 5MPa, 10MPa, 50MPa or 100MPa, and the rolling time is 5s, 30s, 1min, 3min or 5min.

[0017] Step 2: The rolled positive electrode sheet is subjected to atomic layer deposition (ALD) or molecular layer deposition (MLD) technology to construct an interface modification layer, wherein:

[0018] The interface modification layer is composed of one of the following from the electrode side to the electrolyte side: all-inorganic-organic / inorganic hybrid-all-organic, all-organic-organic / inorganic hybrid-all-inorganic, organic / inorganic hybrid-all-organic, organic / inorganic hybrid-all-inorganic, organic / inorganic hybrid-all-inorganic, all-organic-all-inorganic, all-organic-all-inorganic, and all-inorganic-all-organic interface modification layers. The thickness of a single type of interface modification layer is 0.1-50 nm, and the total thickness of the interface modification layer is 1-200 nm. Preferably, the thickness of a single type of interface modification layer is 1 nm, 5 nm, 10 nm, 20 nm or 50 nm, and the total thickness of the interface modification layer is 5 nm, 20 nm, 50 nm, 100 nm or 200 nm, etc.

[0019] The composition of the all-inorganic interface modification layer is metal oxide (such as: Al 2 O 3 , CaO, CuO, Er 2 O 3 , Ga 2 O 3 , HfO 2 ,La 2 O 3 ,MgO,Nb 2 O 5 Sc 2 O 3 、SiO 2 、 2 O 5 、TiO 2 , Y 2 O 3 , Yb 2 O 3 , ZnO, etc.), metal sulfides (such as ZnS, SrS), metal nitrides (such as AlN, GaN, TaNX, TiAlN, TiNX), metal fluorides (such as CaF 2 、LaF3 MgF 2 , SrF 2 )

[0020] The component of the all-organic interface modification layer is at least one of polyazoimide, polyurea, polyamide, poly(3,4-ethylenedioxythiophene), polyimide-polyamide, polythiourea and polyethylene terephthalate;

[0021] The component of the organic / inorganic hybrid interface modification layer is at least one of metal-alcohols (such as aluminum-ethylene glycol, zinc-ethylene glycol, titanium-ethylene glycol, yttrium-ethylene glycol, zinc-ethylene glycol) and metal-phenols (such as aluminum-hydroquinone, zinc-hydroquinone, titanium-hydroquinone, yttrium-hydroquinone, zinc-hydroquinone);

[0022] During the construction of the interface modification layer, a suitable deposition source, deposition temperature, carrier gas inlet speed, inlet time and residence reaction time are selected according to the type and composition of the deposition layer, wherein the metal deposition source is trimethylaluminum, diethylzinc, titanium tetrachloride, trimethylgallium, triethylgallium, tetra(dimethylamine)hafnium, tetra(dimethylamine)germanium, tetra(dimethylamine)zirconium, tetra(dimethylamine)titanium, tetra(methylethylamine)vanadium, penta(ethoxy)tantalum-ethoxytantalum, ferrocene, bis(dimethylamine)magnesium, tri(tetramethylheptyl)heptyl The organic deposition source is one of ytterbium, tris(tetramethylheptanedione)lanthanum, di(tetramethylheptanedione)lead, tris(tetramethylheptanedione)erbium, tris(tetramethylheptanedione)yttrium, methylcyclopentadienylyttrium, tin tetrachloride or tert-butoxide iron; the organic deposition source is one of ethylene glycol, propylene glycol, hydroquinone, ethylenediamine, 1,4-phenylene diisocyanate, carbon tetrachloride, carbon tetrabromide or pentachloropyridine; the inorganic deposition source is one of deionized water, oxygen, ozone, ammonia or nitrogen.

[0023] Compared with the prior art, the present invention has the following advantages:

[0024] (1) Compared with the interface modification layer constructed by conventional liquid coating and vapor deposition, the present invention can realize the atomic-level or molecular-level interface modification layer construction through atomic layer deposition technology or molecular layer deposition technology, which has the advantages of high precision, adjustable structure, good conformality, and wide operating temperature range, and is suitable for Prussian blue materials in cubic block shape.

[0025] (2) Compared with the construction of the interface modification layer at the powder level, the interface modification at the electrode level of the present invention can not only ensure the conductive path of the electrode material and the conductive material, reduce ohmic polarization, but also reduce the consumption of deposition raw materials. In addition, it can also improve the deposition efficiency and reduce the risk of cabin contamination.

[0026] (3) The present invention can give full play to the characteristics of various types of interface modification layers by introducing multiple interface modification layers. The all-inorganic interface modification layer has a higher Young's modulus, which can improve the corrosion resistance and mechanical strength of the interface; the all-organic interface modification layer has higher elasticity and electronic conductivity, which can reduce ohmic polarization and battery internal resistance; the organic / inorganic hybrid interface modification layer can improve the wettability of the electrode and reduce the capacity loss caused by concentration polarization.

[0027] (4) Compared with the atomic layer deposition technology or molecular layer deposition technology adopted in other patents, the present invention can customize an interface modification layer with a component concentration gradient by designing a molecular-level interface modification layer to target the failure mechanisms of different types of Prussian blue materials (such as the Jan-Taylor effect of Mn-PBA and the problem of excessive crystal water in Fe-PBA).

[0028] (5) The multi-component interface modification layer of the present invention can significantly improve the cycle performance and safety performance of the Prussian blue positive electrode material without changing the intrinsic structure of the Prussian blue positive electrode material, and has little effect on the discharge specific capacity of the electrode material.

[0029] (6) The multi-component interface modification layer of the present invention can reduce the catalytic decomposition effect of the surface defects of Prussian blue materials on the electrolyte during the cycle, reduce the dissolution of transition metals and the generation of dead sodium, help improve the coulombic efficiency and cycle performance of the battery, and reduce the safety hazards caused by the acidification of the electrolyte.

[0030] (7) The sodium ion battery prepared using the positive electrode material provided by the present invention has a high cycle capacity retention rate and does not show significant changes during the standard number of cycles. It has excellent quality and meets industry standards. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 The scanning electron microscope pictures before and after the construction of the interface modification layer are as follows: (a) before the construction of the interface modification layer, (b) after the construction of the interface modification layer (corresponding to Example 1), (c) after the construction of the interface modification layer (corresponding to Example 2), (d) after the construction of the interface modification layer (corresponding to Example 3);

[0032] Figure 2 The X-ray diffraction patterns of Comparative Example 1 and Examples 1-3;

[0033] Figure 3 Schematic diagram for constructing the all-inorganic-organic / inorganic hybrid interface modification layer of Example 4. DETAILED DESCRIPTION

[0034] The technical solution of the present invention is further described below in conjunction with the embodiments, but is not limited thereto. Any modification or equivalent replacement of the technical solution of the present invention without departing from the spirit and scope of the technical solution of the present invention should be included in the protection scope of the present invention.

[0035] Example 1

[0036] This embodiment provides a method for constructing an all-inorganic-organic / inorganic hybrid-all-organic interface modification layer, the method comprising the following steps:

[0037] (1) By mass, 7 parts of Na 1.95 Mn 0.5 Fe 0.5 [Fe(CN) 6 ] 0.95 1.5H 2 O, 1 part super P, 1 part Ketjen black and 1 part PVDF NMP solution were made into slurry, coated with a thickness of 130 μm, transferred to a vacuum drying oven and dried at 150°C for 12 hours. After cooling, it was rolled at 10 MPa for 5 minutes by a roller press and then transferred to an atomic layer deposition device.

[0038] (2) Titanium tetrachloride and ultrapure water are used as deposition raw materials to construct the innermost all-inorganic interface modification layer: the deposition plate temperature is 120°C, the deposition chamber ambient temperature is 300°C, the deposition source temperature is 25°C, and the deposition source carrier gas is high-purity argon. First, the titanium tetrachloride deposition raw material is transported by carrier gas, the air intake rate is 150sccm, the air intake time is 0.2s, and the chamber cleaning time is 30s. Then, the ultrapure water deposition raw material is transported by carrier gas for further reaction, the air intake rate is 150sccm, the air intake time is 0.2s, and the chamber cleaning time is 30s. Repeat the above deposition cycle 20 times to form the innermost all-inorganic interface modification layer.

[0039] (3) Using diethyl zinc and ethylene glycol as deposition raw materials to construct an organic / inorganic hybrid interface modification layer of the intermediate layer: the deposition plate temperature is 120°C, the deposition chamber ambient temperature is 300°C, the deposition source diethyl zinc temperature is 25°C, the deposition source ethylene glycol temperature is 90°C, and the deposition source carrier gas is high-purity argon. First, the diethyl zinc deposition raw material is transported by carrier gas, the air intake rate is 150sccm, the air intake time is 0.01s, and the chamber cleaning time is 40s. Then, the ethylene glycol deposition raw material is transported by carrier gas for further reaction, the air intake rate is 150sccm, the air intake time is 0.01s, and the chamber cleaning time is 40s. Repeat the above deposition cycle 20 times to form an organic / inorganic hybrid interface modification layer of the intermediate layer.

[0040] (4) The outermost all-organic interface modification layer is constructed using ethylenediamine and 1,4-phenylene diisocyanate as deposition raw materials: the deposition plate temperature is 65°C, the deposition chamber ambient temperature is 200°C, the deposition source ethylenediamine temperature is 25°C, the deposition source 1,4-phenylene diisocyanate temperature is 90°C, and the deposition source carrier gas is high-purity argon. First, the ethylenediamine deposition raw material is transported by carrier gas, the air intake rate is 150sccm, the air intake time is 0.2s, and the chamber cleaning time is 30s. Then, the 1,4-phenylene diisocyanate deposition raw material is transported by carrier gas for further reaction, the air intake rate is 150sccm, the air intake time is 1s, and the chamber cleaning time is 30s. Repeat the above deposition cycle 20 times to form the outermost all-organic interface modification layer.

[0041] (4) After the temperature drops to 40°C, the electrode is taken out and cut into discs with a diameter of 14 mm. The battery is assembled using a sodium sheet as the counter electrode, 1 M sodium perchlorate as the electrolyte, and equal volumes of EC and PC as the electrolyte. FEC with a volume fraction of 5% is additionally added to the electrolyte.

[0042] Example 2

[0043] This embodiment provides a method for constructing an all-organic-organic / inorganic hybrid-all-inorganic interface modification layer, the method comprising the following steps:

[0044] (1) By mass, 7 parts of Na 1.95 Mn 0.6 Fe 0.4 [Fe(CN) 6 ] 0.95 1.5H 2 O, 1 part super P, 1 part Ketjen black and 1 part PVDF NMP solution were made into slurry, coated with a thickness of 130 μm, transferred to a vacuum drying oven and dried at 150°C for 12 hours. After cooling, it was rolled on a roller press at 10 MPa for 5 minutes.

[0045] (2) The innermost all-organic interface modification layer is constructed using ethylenediamine and 1,4-phenylene diisocyanate as deposition raw materials: the deposition plate temperature is 65°C, the deposition chamber ambient temperature is 200°C, the deposition source ethylenediamine temperature is 25°C, the deposition source 1,4-phenylene diisocyanate temperature is 90°C, and the deposition source carrier gas is high-purity argon. First, the ethylenediamine deposition raw material is transported by carrier gas, the air intake rate is 150sccm, the air intake time is 0.2s, and the chamber cleaning time is 30s. Then, the 1,4-phenylene diisocyanate deposition raw material is transported by carrier gas for further reaction, the air intake rate is 150sccm, the air intake time is 1s, and the chamber cleaning time is 30s. Repeat the above deposition cycle 20 times to form the innermost all-organic interface modification layer.

[0046] (3) Using titanium tetrachloride and ethylene glycol as deposition raw materials to construct an organic / inorganic hybrid interface modification layer of the intermediate layer: the deposition plate temperature is 120°C, the deposition chamber ambient temperature is 300°C, the deposition source titanium tetrachloride temperature is 25°C, the deposition source ethylene glycol temperature is 90°C, and the deposition source carrier gas is high-purity argon. First, the titanium tetrachloride deposition raw material is transported by carrier gas, the air intake rate is 150sccm, the air intake time is 0.01s, and the chamber cleaning time is 40s. Then, the ethylene glycol deposition raw material is transported by carrier gas for further reaction, the air intake rate is 150sccm, the air intake time is 0.01s, and the chamber cleaning time is 40s. Repeat the above deposition cycle 20 times to form an organic / inorganic hybrid interface modification layer of the intermediate layer.

[0047] (4) Use titanium tetrachloride and ultrapure water as deposition raw materials to construct the outermost all-inorganic interface modification layer: the deposition plate temperature is 120°C, the deposition chamber ambient temperature is 300°C, the deposition source temperature is 25°C, and the deposition source carrier gas is high-purity argon. First, the titanium tetrachloride deposition raw material is transported by carrier gas, the air intake rate is 150sccm, the air intake time is 0.2s, and the chamber cleaning time is 30s. Then, the high-purity water deposition raw material is transported by carrier gas for further reaction, the air intake rate is 150sccm, the air intake time is 0.2s, and the chamber cleaning time is 30s. Repeat the above deposition cycle 20 times to form the outermost all-inorganic interface modification layer.

[0048] (5) After the temperature drops to 40°C, the electrode is taken out and cut into discs with a diameter of 14 mm. The battery is assembled using a sodium sheet as the counter electrode, 1 M sodium perchlorate as the electrolyte, and equal volumes of EC and PC as the electrolyte. FEC with a volume fraction of 5% is additionally added to the electrolyte.

[0049] Example 3

[0050] This embodiment provides a method for constructing an all-organic-all-inorganic interface modification layer, the method comprising the following steps:

[0051] (1) By mass, 7 parts of Na 1.95 Mn 0.7 Fe 0.3 [Fe(CN) 6 ] 0.95 1.5H 2 O, 1 part super P, 1 part Ketjen black and 1 part PVDF NMP solution were made into slurry, coated with a thickness of 130 μm, transferred to a vacuum drying oven and dried at 150°C for 12 hours. After cooling, it was rolled on a roller press at 10 MPa for 5 minutes.

[0052] (2) The innermost all-organic interface modification layer is constructed using ethylenediamine and hydroquinone as deposition raw materials: the deposition plate temperature is 120°C, the deposition chamber ambient temperature is 200°C, the deposition source ethylenediamine temperature is 25°C, the deposition source hydroquinone temperature is 200°C, and the deposition source carrier gas is high-purity argon. First, the ethylenediamine deposition raw material is transported by carrier gas, the air intake rate is 150sccm, the air intake time is 0.2s, and the chamber cleaning time is 30s. Then, the hydroquinone deposition raw material is transported by carrier gas for further reaction, the air intake rate is 150sccm, the air intake time is 1s, and the chamber cleaning time is 30s. Repeat the above deposition cycle 20 times to form the innermost all-organic interface modification layer.

[0053] (2) Using methylcyclopentadienyl yttrium and ultrapure water as deposition raw materials, the outermost all-inorganic interface modification layer is constructed: the deposition plate temperature is 120°C, the deposition chamber ambient temperature is 300°C, the deposition source methylcyclopentadienyl yttrium temperature is 140°C, the deposition source ultrapure water temperature is 25°C, and the deposition source carrier gas is high-purity argon. First, the titanium tetrachloride deposition raw material is transported by carrier gas, the air intake rate is 150sccm, the air intake time is 0.2s, and the chamber cleaning time is 30s. Then, the ultrapure water deposition raw material is transported by carrier gas for further reaction, the air intake rate is 150sccm, the air intake time is 0.2s, and the chamber cleaning time is 30s. Repeat the above deposition cycle 20 times to form the outermost all-inorganic interface modification layer.

[0054] (3) The obtained electrode pieces were cut into discs with a diameter of 14 mm, and a battery was assembled using a sodium sheet as a counter electrode, 1 M sodium perchlorate as an electrolyte, equal volumes of EC and PC as an electrolyte, and 5% by volume of FEC was additionally added to the electrolyte.

[0055] Example 4

[0056] This embodiment provides a method for constructing an all-inorganic-organic / inorganic hybrid interface modification layer, such as Figure 3 As shown, the method comprises the following steps:

[0057] (1) By mass, the slurry consists of 90 parts of Na 1.95 Mn 0.6 Fe 0.3 Co 0.1 [Fe(CN) 6 ] 0.95 1.5H 2 O Prussian blue active material, 2 parts superP, 2 parts Ketjen black, 2 parts carbon nanotubes, 4 parts PVDF NMP solution. Coating, thickness of 150μm, transferred to a vacuum drying oven at 170℃ for 12h. After cooling, roll press at 10MPa for 5min.

[0058] (2) The innermost all-inorganic interface modification layer is constructed using titanium tetrachloride and ultrapure water as deposition raw materials: the deposition plate temperature is 120°C, the deposition chamber ambient temperature is 200°C, the deposition source temperature is 25°C, and the deposition source carrier gas is high-purity argon. First, the titanium tetrachloride deposition raw material is transported by carrier gas, the air intake rate is 150sccm, the air intake time is 0.2s, and the chamber cleaning time is 30s. Then, the ultrapure water deposition raw material is further reacted by carrier gas transportation, the air intake rate is 150sccm, the air intake time is 0.2s, and the chamber cleaning time is 30s. Repeat the above deposition cycle 100 times to form the innermost all-inorganic interface modification layer.

[0059] (2) Using diethyl zinc and ethylene glycol as deposition raw materials, the outermost organic / inorganic hybrid interface modification layer was constructed: the deposition plate temperature was 120°C, the deposition chamber ambient temperature was 300°C, the deposition source ethylene glycol temperature was 100°C, the deposition source diethyl zinc temperature was 25°C, and the deposition source carrier gas was high-purity argon. First, the titanium tetrachloride deposition raw material was transported by carrier gas, with an intake rate of 150sccm, an intake time of 0.6s, and a chamber cleaning time of 30s. Subsequently, the ultrapure water deposition raw material was transported by carrier gas for further reaction, with an intake rate of 150sccm, an intake time of 1s, and a chamber cleaning time of 30s. The above deposition cycle was repeated 50 times to form the outermost organic / inorganic hybrid interface modification layer.

[0060] (3) The obtained electrode pieces were cut into discs with a diameter of 14 mm, and a battery was assembled using a sodium sheet as a counter electrode, 1 M sodium perchlorate as an electrolyte, equal volumes of EC and DEC as an electrolyte, and 2% by volume of FEC was additionally added to the electrolyte.

[0061] Example 5

[0062] This embodiment provides a method for constructing an organic / inorganic hybrid-all-inorganic interface modification layer, the method comprising the following steps:

[0063] (1) By mass, the slurry consists of 85 parts of Na 1.95 Mn 0.7 Fe 0.2 Co 0.1 [Fe(CN) 6 ] 0.95 1.5H 2 O Prussian blue active material, 5 parts of Ketjen black, 2 parts of carbon nanotubes, 2 parts of graphene, 6 parts of PAA NMP solution. Coating was performed with a thickness of 150 μm, and transferred to a vacuum drying oven and dried at 150°C for 12 hours. After cooling, it was rolled at 10 MPa for 5 minutes by a roller press.

[0064] (2) The innermost all-inorganic interface modification layer is constructed using tris(tetramethylheptanedione) erbium and hydroquinone as deposition raw materials: the deposition plate temperature is 120°C, the deposition chamber ambient temperature is 200°C, the deposition source temperature is 180°C, and the deposition source carrier gas is high-purity argon. First, the tris(tetramethylheptanedione) erbium deposition raw material is transported by carrier gas, the air intake rate is 150sccm, the air intake time is 0.5s, and the chamber cleaning time is 60s. Subsequently, the hydroquinone deposition raw material is further reacted by carrier gas transportation, the air intake rate is 150sccm, the air intake time is 0.5s, and the chamber cleaning time is 60s. Repeat the above deposition cycle 20 times to form the innermost organic / inorganic hybrid modification layer.

[0065] (2) Using trimethylgallium and ultrapure water as deposition raw materials, the outermost organic / inorganic hybrid interface modification layer was constructed: the deposition plate temperature was 120°C, the deposition chamber ambient temperature was 300°C, the deposition source temperature was 25°C, and the deposition source carrier gas was high-purity argon. First, the trimethylgallium deposition raw material was transported by carrier gas, with an intake rate of 150sccm, an intake time of 0.2s, and a chamber cleaning time of 30s. Subsequently, the ultrapure water deposition raw material was transported by carrier gas for further reaction, with an intake rate of 150sccm, an intake time of 0.2s, and a chamber cleaning time of 30s. The above deposition cycle was repeated 50 times to form the outermost all-inorganic interface modification layer.

[0066] (3) The obtained electrode pieces were cut into discs with a diameter of 14 mm, and a battery was assembled using a sodium sheet as a counter electrode, 1 M sodium perchlorate as an electrolyte, equal volumes of EC and DEC as an electrolyte, and 2% by volume of FEC was additionally added to the electrolyte.

[0067] Example 6

[0068] The difference between this embodiment and embodiment 1-5 is that the chemical formula of the Prussian blue positive electrode material is Li 0.25 Na 0.95 K 0.2 5 Mg 0.25 Ca 0.25 Mn 0.25 Fe 0.25 Co 0.25 Ni 0.25 [Fe(CN) 6 ] 0.95 1.5H 2 O.

[0069] Example 7

[0070] The difference between this embodiment and embodiment 1-5 is that the chemical formula of the Prussian blue positive electrode material is Na 1K0.25Zn0.7 Mn 0. 6 Fe0.3 Zr 0.025 Nb 0.025 Ag 0.025 La 0.025 [Fe(CN) 6 ] 0.95 1.5H 2 O.

[0071] Example 8

[0072] The difference between this embodiment and embodiment 1-5 is that the chemical formula of the Prussian blue positive electrode material is Na 1 K 0.95 Mn 0.6 Fe 0.2 Zn 0.04 Cu 0.04 Ru 0.04 Ce 0.04 Pr 0.04 [Fe(CN) 6 ] 0.95 1.5H 2 O.

[0073] Example 9

[0074] The difference between this embodiment and embodiment 1-5 is that the chemical formula of the Prussian blue positive electrode material is Na 0.75 K 0.75 Zn 0.4 5 Mn 0.6 Fe 0.3 Co 0.02 Ga 0.02 Y 0.02 Ru 0.02 Sm 0.02 [Fe(CN) 6 ] 0.95 1.5H 2 O.

[0075] Comparative Example 1

[0076] This embodiment provides a Prussian blue positive electrode sheet without an interface modification layer, comprising the following steps:

[0077] (1) By mass, 7 parts of Na 1.95 Mn 0.5 Fe 0.5 [Fe(CN) 6 ] 0.95 1.5H 2O, 1 part of superp, 1 part of Ketjen black and 1 part of PVDF NMP solution were made into slurry, coated with a thickness of 130 μm, transferred to a vacuum drying oven and dried at 150°C for 12 hours. After cooling, it was rolled on a roller press at 10 MPa for 5 minutes.

[0078] (2) The obtained electrode pieces were cut into discs with a diameter of 14 mm, and a battery was assembled using a sodium sheet as a counter electrode, 1 M sodium perchlorate as an electrolyte, equal volumes of EC and PC as an electrolyte, and 5% by volume of FEC was additionally added to the electrolyte.

[0079] A sodium ion battery, comprising the positive electrode sheets prepared in Examples 1 to 9 and Comparative Example 1, the performance of which is shown in Table 1:

[0080] Table 1

[0081]

[0082] From the comparison results in Table 1, it can be seen that the positive electrode sheet prepared by the present invention has a significant improvement in electrode cycle performance, and although the capacity is slightly reduced, it is still acceptable. Figure 1 ) and XRD patterns ( Figure 2 ) It can be found that the morphology and phase structure of the Prussian blue analogue crystals did not change significantly before and after deposition, proving that the deposited layer does not have a destructive effect on the electrode material structure.

Claims

1. A method for constructing an interface modification layer of a Prussian blue electrode material, characterized in that The method comprises the following steps: Step 1: preparing a Prussian blue positive electrode material into a positive electrode sheet and rolling it; Step 2: The rolled positive electrode sheet is subjected to atomic layer deposition or molecular layer deposition technology to construct an interface modification layer, wherein: the interface modification layer is composed of one of the following from the electrode side to the electrolyte side: all-inorganic-organic / inorganic hybrid-all-organic, all-organic-organic / inorganic hybrid-all-inorganic, organic / inorganic hybrid-all-organic, organic / inorganic hybrid-all-inorganic, organic / inorganic hybrid-all-inorganic, all-organic-all-inorganic, all-organic-all-inorganic, and all-inorganic-all-organic interface modification layers.

2. The method for constructing an interface modification layer of a Prussian blue electrode material according to claim 1, characterized in that The positive electrode plate is composed of a Prussian blue active material, conductive carbon and a binder, wherein the mass fraction of the Prussian blue active material is 70-90%, the mass fraction of the conductive carbon is 6-20%, and the mass fraction of the binder is 4-10%.

3. The method for constructing an interface modification layer of a Prussian blue electrode material according to claim 2, characterized in that The chemical formula of the Prussian blue positive electrode material is A x M[Fe(CN)6] 1-y nH2O, wherein 0≤x≤2, 0≤y<1, 0<n≤3.5, A includes one or more of Li, Na, K, Mg, Ca, Zn, and M includes Mn and Fe elements.

4. The method for constructing an interface modification layer of a Prussian blue electrode material according to claim 3, characterized in that The M also includes one or a combination of Sc, Ti, V, Cr, Co, Ni, Cu, Zn, Ga, Y, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Cd, In, Sn, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm and Yb.

5. The method for constructing an interface modification layer of a Prussian blue electrode material according to claim 2, characterized in that The conductive carbon is one or more of superP, Ketjen black, carbon nanotubes and graphene; the binder is one of PVDF, PTFE, sodium alginate and PAA.

6. The method for constructing an interface modification layer of a Prussian blue electrode material according to claim 1, characterized in that The rolling pressure of the positive electrode sheet is 5-100 MPa, and the rolling time is 5s-5min.

7. The method for constructing an interface modification layer of a Prussian blue electrode material according to claim 1, characterized in that In the interface modification layer, the thickness of the interface modification layer of the all-inorganic interface modification layer, the all-organic interface modification layer, and the organic / inorganic hybrid interface modification layer is 0.1 to 50 nm, and the total thickness of the interface modification layer is 1 to 200 nm.

8. The method for constructing an interface modification layer of a Prussian blue electrode material according to claim 1 or 7, characterized in that The component of the all-inorganic interface modification layer is at least one of metal oxides, metal sulfides, metal nitrides, and metal fluorides; the component of the all-organic interface modification layer is at least one of polyazoimide, polyurea, polyamide, poly(3,4-ethylenedioxythiophene), polyimide-polyamide, polythiourea, and polyethylene terephthalate; the component of the organic / inorganic hybrid interface modification layer is at least one of metal-alcohols and metal-phenols.

9. The method for constructing an interface modification layer of a Prussian blue electrode material according to claim 8, characterized in that The metal oxide is one or more of Al2O3, CaO, CuO, Er2O3, Ga2O3, HfO2, La2O3, MgO, Nb2O5, Sc2O3, SiO2, Ta2O5, TiO2, Y2O3, Yb2O3, and ZnO; the metal sulfide is one or two of ZnS and SrS; the metal nitride is one or more of AlN, GaN, TaNX, TiAlN, and TiNX; the metal fluoride is one or more of CaF2, LaF3, MgF2, and SrF2; the metal-alcohol is at least one of aluminum-ethylene glycol, zinc-ethylene glycol, titanium-ethylene glycol, yttrium-ethylene glycol, and zinc-ethylene glycol; the metal-phenol is at least one of aluminum-hydroquinone, zinc-hydroquinone, titanium-hydroquinone, yttrium-hydroquinone, and zinc-hydroquinone.

10. The method for constructing an interface modification layer of a Prussian blue electrode material according to claim 1, characterized in that During the construction of the interface modification layer, a metal deposition source, an organic deposition source and an inorganic deposition source are selected according to the type and composition of the deposition layer, wherein the metal deposition source is trimethylaluminum, diethylzinc, titanium tetrachloride, trimethylgallium, triethylgallium, tetra(dimethylamine)hafnium, tetra(dimethylamine)germanium, tetra(dimethylamine)zirconium, tetra(dimethylamine)titanium, tetra(methylethylamine)vanadium, penta(ethoxy)tantalum-ethoxytantalum, ferrocene, bis(dimethylamine)magnesium, tri(tetramethylheptanedione)ytterbium, tri( The organic deposition source is one of lanthanum tetramethylheptanedione, lead di(tetramethylheptanedione), erbium tri(tetramethylheptanedione), yttrium tri(tetramethylheptanedione), yttrium methylcyclopentadienyl, tin tetrachloride or tert-butoxide iron; the organic deposition source is one of ethylene glycol, propylene glycol, hydroquinone, ethylenediamine, 1,4-phenylene diisocyanate, carbon tetrachloride, carbon tetrabromide or pentachloropyridine; the inorganic deposition source is one of deionized water, oxygen, ozone, ammonia or nitrogen.

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