Nickel salt modified sulfurized anthracene-based polymer, and preparation method and application thereof

Abstract

The application discloses a nickel salt modified vulcanized anthryl polymer and a preparation method and application thereof. The nickel salt modified vulcanized anthryl polymer is obtained by modifying a vulcanized anthryl polymer with a nickel salt. The preparation process is that the nickel salt and the vulcanized anthryl polymer are directly mixed uniformly and calcined under the protection of an inert atmosphere. The vulcanized anthryl polymer is simply modified by doping with the nickel salt, and is used as a positive electrode material of a magnesium ion battery, so that the electrochemical performance of the vulcanized anthryl polymer is obviously improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of battery electrode materials, and particularly relates to a nickel salt modified sulfurized anthracene-based polymer and a preparation method and application thereof. BACKGROUND

[0002] Magnesium batteries have good application prospects in large-scale battery energy storage systems due to their advantages of rich resources, low cost and high volumetric energy density (3833 mAh cm -3 ), and become an ideal next-generation electrochemical energy storage device. However, due to the fact that the magnesium negative electrode is easily reacted with the traditional electrolyte and forms a passivation film that is not conductive to Mg 2+ , the reversible deposition / dissolution process of Mg 2+ is hindered. In addition, the poor compatibility of the magnesium battery positive electrode material with the electrolyte and the strong electrostatic interaction between the magnesium battery positive electrode material and Mg 2+ make it difficult for the magnesium battery energy storage technology to meet the actual requirements. Therefore, it is urgent to find a magnesium battery positive electrode material that can realize highly reversible magnesium storage and is compatible with the electrolyte.

[0003] Unlike non-polar positive electrode materials with rigid structures, which usually need to design suitable crystal structures to realize the reversible insertion and extraction of carriers, organic positive electrode materials realize ion storage based on the charge transfer reaction of redox centers, and thus are not limited by the size and charge of metal ions. At the same time, the intermolecular interaction force between the organic positive electrode material and the magnesium ion involved in the reaction is small, the bond rearrangement is easy, the Mg 2+ migration path is flexible, and the migration barrier is low, thereby realizing high-rate Mg 2+ storage. In addition, some organic electrode materials with redox activity can be obtained from natural substances at low energy consumption, have the advantages of low cost, high quality energy density and flexible structure, and are not dependent on scarce transition metal resources, and thus show great application prospects. However, due to the low intrinsic conductivity of organic molecules and the easy solubility in organic electrolyte, the energy, power density and long-term cycle life are seriously limited, which restricts the practical application of organic electrode materials in electrochemical energy storage systems.

[0004] Therefore, Chinese Patent CN115975194 B fixes sulfur with redox activity on a π-conjugated anthracene skeleton to enhance the molecular constraint force, and prepares a sulfurized anthracene-based polymer with high sulfur loading, multiple magnesium storage sites and semiconductor characteristics. However, the organic sulfur molecules still face the following challenges during magnesium storage: the polarization of the first cycle is large, resulting in a low coulombic efficiency (about 60 %), and the subsequent cycles are not stable due to the inherent slow diffusion kinetics in the development of rechargeable magnesium batteries, and there is a capacity loss. SUMMARY

[0005] In order to solve the above technical problems, the purpose of the present application is to provide a nickel salt modified sulfurized anthracene-based polymer and its preparation method and application, which is used as a positive electrode material for magnesium ion batteries by simple nickel salt doping modification of the sulfurized anthracene-based polymer, significantly improving its electrochemical performance.

[0006] In order to achieve the above technical purpose, the present application adopts the following technical scheme:

[0007] A nickel salt modified sulfurized anthracene-based polymer, the general structure formula is shown as formula (I):

[0008] (I) is modified by a nickel salt on a sulfurized anthracene-based polymer.

[0009] Preferably, the nickel salt is selected from one or more of nickel chloride, bromide, oxalate, nitrate, and sulfate.

[0010] It should be noted that the sulfurized anthracene-based polymer in the present application can be obtained by referring to Chinese patent CN115975194 B, which will not be described here.

[0011] The present application also provides a preparation method of the above-mentioned nickel salt modified sulfurized anthracene-based polymer, which is to mix the nickel salt and the sulfurized anthracene-based polymer uniformly, and then calcine under the protection of inert atmosphere.

[0012] In the present application, the mixing method can adopt the common mixing method in the prior art, such as stirring mixing, ultrasonic mixing, ball milling mixing, etc., and there is no special requirement.

[0013] Preferably, the mass percentage content ratio of the nickel salt and the sulfurized anthracene-based polymer is 0.5-5:95-99.5.

[0014] Preferably, the calcination temperature is 200-300℃, and the time is 2-4h.

[0015] The present application also provides a magnesium battery positive electrode, which comprises a current collector and an active material layer coated on at least one side surface of the current collector; the active material layer comprises the above-mentioned nickel salt modified sulfurized anthracene-based polymer; the nickel salt modified sulfurized anthracene-based polymer, a conductive agent, and a binder are dispersed uniformly in a solvent to form a positive electrode slurry, which is then uniformly coated on the current collector and vacuum dried to obtain the magnesium battery positive electrode.

[0016] Preferably, the mass ratio of the nickel salt modified sulfurized anthracene polymer, the conductive agent and the binder is 5-9:1-14:1; the current collector is one of stainless steel, aluminum, copper, nickel-based metal or carbon matrix (such as carbon cloth, carbon paper, etc.); the conductive agent is one of conductive carbon black (such as acetylene black, ketjen black, Super-P, etc.), conductive graphite (such as KS-6, KS-15, SO, etc.), carbon nanotubes or graphene; the binder is one of natural binders (such as carboxymethyl cellulose, guar gum, sodium alginate, gum arabic, xanthan gum, etc.) or artificial binders (such as polyvinylidene fluoride, polytetrafluoroethylene, polyacrylic acid, butadiene-styrene rubber, polyamide, polyvinyl alcohol, poly 3,4-ethylenedioxythiophene / polystyrene sulfonate); the solvent is one of N-methyl pyrrolidone, ethanol, deionized water.

[0017] The application further provides a magnesium secondary battery comprising the above magnesium battery positive electrode.

[0018] The application has the following beneficial effects:

[0019] 1. The application uses a simple nickel salt doping modification on a sulfurized anthracene polymer as a magnesium ion battery positive electrode material, which exhibits excellent ionic conductivity (1.761×10 -4 S·cm -1 ).

[0020] 2. The application uses a simple nickel salt doping modification on a sulfurized anthracene polymer, which can expose more active sites for Mg 2+ reaction, and the capacity retention rate of the nickel salt modified sulfurized anthracene polymer positive electrode material is 98.6% (0.0014% attenuation per cycle) after 1000 cycles at 1.0 A g -1 , and the cycle stability is significantly improved.

[0021] 3. The application uses a simple nickel salt doping modification on a sulfurized anthracene polymer, effectively regulates the energy band structure of the sulfurized anthracene polymer, significantly reduces the electron transition level, has higher reversibility and smaller electrochemical process polarization (0.79 V), promotes the diffusion rate of Mg 2+ , and thus has excellent electrochemical performance. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 is the cyclic voltammetry curve of the magnesium battery assembled by 2.54% NiCl2-ANS in Example 1, and the scanning speed is 2 mV s -1 .

[0023] Figure 2is the cyclic voltammetry comparison plot of the magnesium battery assembled with 2.54% NiCl2-ANS in Example 1 and ANS in Comparative Example 1, scan rate 2.0 mV s -1 .

[0024] Figure 3 is the first three cycle charge-discharge plot of the magnesium battery assembled with 2.54% NiCl2-ANS in Example 1, current density 0.3 A g -1 .

[0025] Figure 4 is the first cycle charge-discharge plot of the magnesium battery assembled with 2.54% NiCl2-ANS in Example 1 and ANS in Comparative Example 1, current density 0.3 A g -1 .

[0026] Figure 5 is the second cycle charge-discharge plot of the magnesium battery assembled with 2.54% NiCl2-ANS in Example 1 and ANS in Comparative Example 1, current density 0.3 A g -1 .

[0027] Figure 6 is the cycle performance plot of the magnesium battery assembled with 2.54% NiCl2-ANS in Example 1, current density 0.3 Ag -1 .

[0028] Figure 7 is the cyclic voltammetry comparison plot of the magnesium battery assembled with 2.54% NiCl2-ANS in Example 1 and ANS in Comparative Example 1, current density 1.0 A g -1 .

[0029] Figure 8 is the rate performance plot of the magnesium battery assembled with 2.54% NiCl2-ANS in Example 1.

[0030] Figure 9 is the rate performance plot of the magnesium battery assembled with 2.54% NiCl2-ANS in Example 1 and the corresponding charge-discharge plots at different rates.

[0031] Figure 10 is the cycle performance plot of the magnesium battery assembled with 2.54% NiCl2-ANS in Example 1 and 0.67% NiCl2-ANS in Example 2, current density 0.3 A g -1 .

[0032] Figure 11 is the first cycle charge-discharge plot of the magnesium battery assembled with 2.54% NiCl2-ANS in Example 1 and 0.67% NiCl2-ANS in Example 2.

[0033] Figure 12 is a comparison chart of charge-discharge curves of the first cycle of the magnesium battery assembled with 2.54% NiCl2-ANS in Example 1, CoCl2-ANS in Comparative Example 2 and FeCl3-ANS in Comparative Example 3, and the current density is 0.3 A g -1 .

[0034] Figure 13 is a comparison chart of charge-discharge curves of the third cycle of the magnesium battery assembled with 2.54% NiCl2-ANS in Example 1, CoCl2-ANS in Comparative Example 2 and FeCl3-ANS in Comparative Example 3, and the current density is 0.3 A g -1 . DETAILED DESCRIPTION

[0035] The technical solutions of the present application will be further described in detail below in combination with specific examples, but the application and expansion of the present application are not limited thereto.

[0036] The nickel salt modified sulfurized anthracene-based polymer in the present application, wherein the sulfurized anthracene-based polymer is denoted as ANS, AN represents an anthracene ring, and S represents a sulfur chain, and the nickel salt is denoted as Ni 2+ X, X represents chloride ion, bromide ion, oxalate ion or sulfate ion; the general structure thereof is shown in formula (I):

[0037] (I).

[0038] The sulfurized anthracene-based polymer has a complete conjugated fused ring anthracene skeleton, each anthracene skeleton unit is connected by a sulfur chain or directly by the carbon of the fused ring anthracene and saturated by the sulfur chain, the wavy line in formula (I) represents the connecting bond between each repeating unit, the number of repeating units is 2-10, and the sulfur chain is =S=, -S- or -S-S-.

[0039] The anthracene skeleton of the above-mentioned sulfurized anthracene-based polymer is bonded in different ways and has a structure fragment shown in formula (II):

[0040] (II).

[0041] The preparation method of the above-mentioned sulfurized anthracene-based polymer is specifically as follows:

[0042] The fused ring anthracene and excess sublimed sulfur are mixed uniformly and then placed in a reactor and calcined under an inert atmosphere, then the reaction is continued by heating to remove excess sulfur, and then cooled to room temperature to obtain a black product, i.e. the sulfurized anthracene-based polymer.

[0043] Example 1

[0044] 1.35 mg of NiCl2and 50 mg of ANS were uniformly dispersed in anhydrous ethanol and ultrasonically dispersed for half an hour. Then the ANS containing NiCl2was heated in a blast drying oven at 80°C overnight to dry to obtain a mixed powder. The mixed powder was calcined in argon at a temperature increasing rate of 5°C / min to 200°C for 3 h to obtain a NiCl2-ANS powder. The mass fraction of NiCl2in the NiCl2-ANS powder was 2.54wt% as tested by ICP, and the powder was recorded as 2.54% NiCl2-ANS.

[0045] Example 2

[0046] 0.35 mg of NiCl2and 50 mg of ANS were uniformly dispersed in anhydrous ethanol and ultrasonically dispersed for half an hour. Then the ANS containing NiCl2was heated in a blast drying oven at 80°C overnight to dry to obtain a mixed powder. The mixed powder was calcined in argon at a temperature increasing rate of 5°C / min to 200°C for 3 h to obtain a NiCl2-ANS powder. The mass fraction of NiCl2in the NiCl2-ANS powder was 0.67wt% as tested by ICP, and the powder was recorded as 0.67% NiCl2-ANS.

[0047] Comparative Example 1

[0048] Anthracene (1 g, 5.6 mmol) and excess sublimed sulfur (5 g, 20 mmol) were ground in a marble mortar for 1 h, and after being uniformly mixed, they were placed in a crucible with a cover and put in a tube furnace, heated to 300°C under N2flow in 1 h, and kept at a constant temperature for 3 h to fully react. In order to remove excess sulfur, the mixture was continuously heated to 450°C in 30 min and kept for 3 h, and cooled to room temperature to obtain a black product, i.e. a sulfurized anthracene-based polymer, recorded as ANS.

[0049] Comparative Example 2

[0050] 1.35 mg of CoCl2and 50 mg of ANS were uniformly dispersed in anhydrous ethanol and ultrasonically dispersed for half an hour. Then the ANS containing CoCl2was heated in a blast drying oven at 80°C overnight to dry to obtain a mixed powder. The mixed powder was calcined in argon at a temperature increasing rate of 5°C / min to 200°C for 3 h to obtain a CoCl2-ANS powder.

[0051] Comparative Example 3

[0052] 1.35 mg of FeCl₃ and 50 mg of ANS were uniformly dispersed in anhydrous ethanol and ultrasonically dispersed for half an hour. The FeCl₃-ANS mixture was then dried overnight in an 80°C forced air drying oven to obtain a mixed powder. The mixed powder was then heated to 200°C in argon at a heating rate of 5°C / min and calcined for 3 hours to obtain FeCl₃-ANS powder.

[0053] The positive electrode preparation and magnesium battery assembly process are as follows:

[0054] Each sample was uniformly dispersed in N-methylpyrrolidone with the conductive agent acetylene black and the binder polyvinylidene fluoride at a mass ratio of 7:2:1. The mixture was thoroughly ground into a viscous slurry. The slurry was evenly coated on a stainless steel current collector and then vacuum-dried at 110°C for 12 hours to obtain the magnesium battery positive electrode. A polished magnesium metal sheet was used as the negative electrode. 0.4 mol / LMg[B(hfip)₄]₂ / DME was used as the electrolyte. The magnesium battery positive electrode was assembled in a glove box and then used for electrochemical testing over a voltage range of 0.3-2.8V.

[0055] like Figure 1 As shown, a broad reduction peak was observed at 0.81 V in the first cathodic scan of 2.54% NiCl2-ANS, and two pairs of reversible oxidation peaks were observed at 1.83 / 1.05 V and 1.72 / 1.18 V in the subsequent scans, indicating a reversible (de)magnesiation process of the cathode.

[0056] like Figure 2 As shown in the figure, compared with the blank ANS cathode of comparative example 1, the NiCl2-doped modified ANS cathode exposed more Mg 2+ The active sites of the reaction thus exhibited a higher peak current and smaller polarization (0.79 V).

[0057] like Figure 3 As shown, the 2.54% NiCl2-ANS positive electrode of Example 1 is at 300mA g -1 The first coulombic efficiency at the current density is as high as 87.98%, which is much higher than the 69.5% of the blank ANS positive electrode in comparative example 1 ( Figure 4 The higher average discharge voltage is 1.32 V at 300 mA g -1 Up to 150 mAh g -1 Compared with the blank ANS cathode of Comparative Example 1, the charge-discharge curve of the second cycle of the NiCl2-doped modified ANS cathode shows a smaller polarization ( Figure 5), further proving that NiCl2 is an effective additive for the ANS cathode, indicating that the 2.54% NiCl2-ANS cathode can achieve more stable and reversible magnesium storage during the cycling process. At the same time, the 2.54% NiCl2-ANS cathode has a high discharge specific capacity of 126.9 mAh g -1 after stable cycling for 100 cycles at a current density of 0.3 Ag -1 , and the capacity retention rate is 94.73% (( Figure 6 ). Compared with the blank ANS cathode of Comparative Example 1, which has a capacity of 68.7 mA g -1 and a capacity retention rate of 56.4% after 1000 cycles, the 2.54% NiCl2-ANS cathode still has a discharge specific capacity of 125.3 mAh g -1 and a capacity retention rate of 98.6% after cycling for 1000 cycles at a high current density of 1.0 Ag -1 , showing excellent cycle stability (( Figure 7 ).

[0058] As shown in Figure 8 , the discharge specific capacity of the assembled magnesium battery is 148, 136, 130, 125, 123 and 117 mAh g -1 at current densities of 0.1, 0.3, 0.5, 0.8, 1.0 and 2.0 Ag -1 , respectively. After experiencing an extremely high current density of 2.0 Ag -1 , when the current density is restored to 0.3 Ag -1 , the capacity can still recover to the original capacity value, proving that the cathode can exhibit good electrochemical stability and reversibility at all test rates. At the same time, the voltage platform and specific capacity of the charge-discharge curve at different current densities during the rate test process are well maintained, further revealing the excellent reversibility and fast magnesium storage of the cathode during magnesium storage (( Figure 9 ).

[0059] As shown in Figure 10 and 11 , after the initial cycle, the 2.54% NiCl2-ANS cathode of Example 1 provides a reversible discharge specific capacity of 133 mAh g -1 and a coulombic efficiency of 88%; after 100 cycles, it shows a reversible discharge specific capacity of 127 mAh g -1 , and the capacity retention rate is 94.73%. The 0.67% NiCl2-ANS cathode of Example 2 provides a reversible discharge specific capacity of 118 mAh g -1 and a coulombic efficiency of 84.5%.

[0060] As shown in Figure 12As shown, the 2.54% NiCl2-ANS positive electrode of Example 1 is at 300mA g -1 The first coulombic efficiency at a current density of 1.54% is as high as 92%, which is much higher than the 48% of CoCl2-ANS cathode and 63.7% of FeCl3-ANS cathode. Compared with CoCl2-ANS and FeCl3-ANS cathodes, the charge-discharge curve of the 2.54% NiCl2-ANS cathode in the third cycle shows smaller polarization and higher specific capacity ( Figure 13 ), proving that NiCl2 is an effective additive for ANS cathode and can significantly improve its electrochemical performance.

Claims

1. A nickel salt modified anthracene sulfide polymer, characterized in that: The nickel salt and anthracene sulfide polymer are directly mixed thoroughly and calcined under the protection of an inert atmosphere. The anthracene skeleton of the above-mentioned sulfided anthracene-based polymer is bonded in different ways and has a structural fragment represented by formula (II): (ⅠⅠ)； The nickel salt is selected from one or more of nickel chloride, bromide, oxalate, nitrate, and sulfate; The mass percentage ratio of the nickel salt to the anthracene sulfide polymer is 0.5-5:95-99.5; The calcination temperature is 200-300° C. and the calcination time is 2-4 hours.

2. The method for preparing the nickel salt modified anthracene sulfide polymer according to claim 1, characterized in that: The nickel salt and anthracene sulfide polymer are directly mixed thoroughly and calcined under the protection of an inert atmosphere. The mass percentage ratio of the nickel salt to the anthracene sulfide polymer is 0.5-5:95-99.5; The calcination temperature is 200-300° C. and the calcination time is 2-4 hours.

3. A magnesium battery positive electrode, characterized in that: The invention comprises a current collector and an active material layer coated on at least one side of the current collector; the active material layer comprises the nickel salt-modified anthracene sulfide polymer according to claim 1 or the nickel salt-modified anthracene sulfide polymer obtained by the preparation method according to claim 2; the nickel salt-modified anthracene sulfide polymer, a conductive agent, and a binder are uniformly dispersed in a solvent to form a positive electrode slurry, which is then uniformly coated on the current collector and vacuum dried to obtain a magnesium battery positive electrode.

4. The magnesium battery positive electrode according to claim 3, characterized in that: The mass ratio of the nickel salt-modified anthracene sulfide-based polymer, the conductive agent, and the adhesive is 5-9:1-14:1; the current collector is one of stainless steel, aluminum, copper, nickel-based metal, or carbon matrix; the conductive agent is one of conductive carbon black, conductive graphite, carbon nanotubes, or graphene; the adhesive is one of a natural adhesive or an artificial adhesive; and the solvent is one of N-methylpyrrolidone, ethanol, and deionized water.

5. A magnesium secondary battery, characterized in that: The magnesium battery positive electrode according to claim 3 or 4 is included.

Images