All-solid-state battery based on high-performance silicon negative electrode and conversion type positive electrode and dynamic compensation method for volume expansion of all-solid-state battery

Abstract

The invention discloses an all-solid-state battery based on a high-performance silicon negative electrode and a conversion type positive electrode and a dynamic compensation method for volume expansion of the all-solid-state battery, and belongs to the technical field of all-solid-state lithium ion batteries. The battery is composed of conversion type positive electrode materials such as a Si negative electrode, an S positive electrode and a Se positive electrode and a solid electrolyte; the active material of the negative electrode is LixSi alloy; the reaction equation is (x / 2) S / Se + LixSi = Si + (x / 2) Li2S / Li2Se, wherein 0 lt; x is smaller than or equal to 4.4; a Si negative electrode is matched with a conversion type positive electrode material such as an S positive electrode or a Se positive electrode, and the conversion type positive electrode material such as the S positive electrode or the Se positive electrode has relatively large volume expansion and shrinkage in a battery circulation process, so that a part of volume change of the Si negative electrode in the battery circulation process is made up, and the internal stress change of the battery is reduced; therefore, the problems of falling and inactivation of active substances, internal stress damage to solid electrolyte and the like caused by volume change of the alloying negative electrode and the conversion type positive electrode in the all-solid-state battery in the charging and discharging process are effectively solved, and the cycling stability, coulombic efficiency, economical efficiency and safety of the battery under the ultrahigh loading capacity are effectively improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of all-solid-state lithium-ion batteries, and particularly relates to an all-solid-state battery based on a high-performance silicon negative electrode and a conversion-type positive electrode, and a dynamic compensation method for its volume expansion. Background Art

[0002] In recent years, high-energy rechargeable batteries using alkali metals (such as Li, Na, and K) have developed rapidly. Due to their ultra-high capacity and relatively low reduction potential, the energy density of these batteries far exceeds that of existing lithium-ion batteries. However, the use of alkali metals often results in unstable battery chemical reactions. Taking the relatively common lithium metal negative electrode as an example, lithium dendrites are easily formed during the battery cycling process, inducing battery short circuits. At the same time, uncontrolled exothermic side reactions can cause the combustion of organic electrolytes, resulting in safety accidents.

[0003] Solid-state batteries, which completely replace organic electrolytes, have much higher safety than traditional liquid batteries. In the all-solid-state battery system, the Si negative electrode is considered to be the most promising negative electrode material for all-solid-state lithium-ion batteries due to its extremely high theoretical specific capacity (4200 mAh / g) and abundant natural reserves. At the same time, replacing the lithium metal negative electrode with a Si negative electrode can effectively avoid the occurrence of battery short circuits. However, due to the large volume expansion and contraction (300%) of Si during the charge-discharge cycle process, the internal stress generated will cause irreversible damage cracks to the electrolyte, leading to the rapid growth of lithium dendrites at the electrolyte cracks. Therefore, its commercial application still faces severe challenges. In terms of positive electrode materials, conversion-type positive electrode materials can provide ultra-high capacity and have a relatively low voltage, making them promising candidates for the next-generation solid-state batteries. However, conversion-type positive electrode materials usually undergo large volume changes during the cycling process, resulting in internal stress between the active material and the electrolyte, leading to poor battery cycling performance and Coulomb efficiency. Therefore, solving the internal stress problem of solid-state batteries is the key to the commercial application of conversion-type positive electrode materials. Summary of the Invention

[0004] The present invention provides an all-solid-state battery based on a high-performance silicon negative electrode and a conversion-type positive electrode, and a dynamic compensation method for its volume expansion, which can solve the problems of large volume expansion and contraction of the silicon negative electrode and conversion-type positive electrode materials such as sulfur / selenium during the charge-discharge cycle process, relieve the stress change inside the battery, achieve stable high-rate cycling of the all-solid-state battery at high energy density, and at the same time, the all-solid-state battery assembled based on the present invention has both economy and safety.

[0005] To achieve the above object, the present invention adopts the following technical solutions: An all-solid-state battery based on a high-performance silicon negative electrode and a conversion-type positive electrode, which is composed of a Si negative electrode, a conversion-type positive electrode, and a solid electrolyte; The positive electrode active material is a conversion-type positive electrode material, and the conversion-type positive electrode material includes: chalcogenides: S, Li2S, Se, Li2Se, Te, Li2Te, CoS2, CuS, Cu2S, NiS, FeS2, FeS, FeSe, Co3S4, MnS2, CoSe2, CuSe, MnS; metal halides: AgF, Br2, LiBr, CuF, AgCl, BiF3, I2, LiI, CuCl2, NiCl2, FeCl3, FeCl2, CoCl2, MnCl2, CuF2, CoF3, NiF2, CoF2, FeF3, FeF2, MnF3, CrF3, VF3, TiF3; The active material of the Si electrode is Li x Si alloy. Taking the S positive electrode and the Se positive electrode as examples, the battery reaction equation is (x / 2)S / Se + Li x Si = Si + (x / 2)Li2S / Li2Se, where 0 < x ≤ 4.4; The proportion of prelithiated Si includes but is not limited to Li 0.5 Si, LiSi, Li 1.5 Si, Li 1.71 Si, Li2Si, Li 2.33 Si, Li 2.5 Si, Li3Si, Li 3.25 Si, Li 3.5 Si, Li 3.75 Si, Li4Si, Li 4.4 Si; the Li x Si alloy synthesis and preparation methods include but are not limited to chemical synthesis, electrochemical prelithiation, and electrode spraying of lithium powder method; The solid electrolyte is a borohydride of lithium, a sulfide of lithium, an oxide of lithium, a halide of lithium, a lithium-containing polymer, or a composite thereof, preferably a borohydride of lithium; The borohydrides of lithium include but are not limited to LiBH4, Li4(BH4)3I, Li2B 12 H 12 , Li(CB9H 10 ), Li(CB 11 H 12 ); The sulfide of lithium is 70Li2S - 30P2S5, Li 10 GeP2S 12 , Li6PS5Cl, Li (7-x+y) PS (6-x) Cl (x+y)(0.05 ≤ y ≤ 0.9, -3.0x + 1.8 ≤ y ≤ -3.0x + 5.7), Li6PS5Br, Li6PS5I, Li 10 GeP2S 11.7 O 0.3 、Li 9.54 Si 1.74 P 1.44 S 11.7 Cl 0.3 or Li2Zn 0.5 PS4; The lithium oxide is Li 6.4 La3Zr 1.4 Ta 0.6 O 12 、Li7La3Zr2O 12 or Li 1.3 Al 0.3 Ti 1.7 (PO4)3; The lithium halide is Li3YCl6, Li3ErCl6, Li3InCl6, Li3YBr6, Li3InBr6, Li3ScCl6 or Li 1.75 ZrCl 4.75 O 0.5 ; The polymer matrix is PEO, PMMA, PAN, PVC, PVDF or PVDF-HFP; The electrode includes active material, conductive carbon, and solid electrolyte, and the mass ratios of each part are dynamically adjusted according to the equation a + b + c = 1 (5% ≤ a ≤ 95%, 5% ≤ c ≤ 95%), where a, b, and c are the mass ratios of the active material, conductive carbon, and solid electrolyte respectively; The preparation methods of the powder electrode material composite include physical grinding and mixing, high-temperature heat treatment, vacuum freeze-drying, high-speed centrifugation, dehydration and purification, and carbonization and reduction.

[0006] The above dynamic compensation method for volume expansion of all-solid-state batteries based on high-performance silicon anodes and conversion cathodes matches the Si anode with conversion cathode materials such as S cathode and Se cathode, and utilizes the large volume expansion and contraction of conversion cathode materials such as S cathode and Se cathode during battery cycling to make up for part of the volume change generated by the Si anode during battery cycling, reduce the internal stress change of the battery, and thus avoid mechanical damage to the solid electrolyte.

[0007] Specific design mechanism: During discharge, lithium ions on the negative electrode side move from Li xDuring discharge, lithium ions move from the cathode to the anode and combine with silicon in the anode, causing volume shrinkage; on the cathode side, lithium ions combine with elemental sulfur / selenium to form Li2S / Li2Se, resulting in volume expansion. The volume changes of the anode and cathode compensate for each other, thus achieving the dynamic balance of the overall volume of the solid-state battery. The charging process is vice versa.

[0008] Beneficial effects: The present invention provides an all-solid-state battery based on a high-performance silicon anode and a conversion-type cathode and a method for dynamically compensating for volume expansion. Aiming at the volume change defects of silicon anodes and conversion-type cathode materials such as S / Se, a method for dynamically compensating for volume expansion is innovatively proposed based on a matching solid electrolyte; by using conversion-type cathode materials such as S / Se to match the silicon anode material, the large volume expansion and contraction of conversion-type cathode materials such as S / Se during the battery cycle are utilized to compensate for part of the volume change generated by the silicon anode, thereby reducing the damage to the solid electrolyte. It has a high degree of practicality. At the same time, the matching degree between the anode and cathode is high, and the pressure dynamic compensation system of the conversion-type cathode and the alloy-type anode ensures that the internal stress environment of the battery is suitable for a variety of solid electrolytes, realizing the long-term stable cycle of the battery, significantly alleviating the volume expansion and contraction problems of the silicon anode battery during charge and discharge, reducing the internal stress concentration and the deformation of the internal structure of the battery, ensuring the stability of the electrode materials inside the battery, and thus improving the stability of the battery; Using lithium borohydride as the electrolyte, the interface stability between silicon and the lithium borohydride electrolyte is good, effectively improving the cycle stability of the battery; at the same time, the borohydride electrolyte has the characteristics of high mechanical strength, can better adapt to the volume expansion of the electrode, and is conducive to achieving the balance of internal stress in the battery; In summary, the present invention can effectively improve problems such as the shedding and inactivation of active substances caused by volume expansion and contraction during charge and discharge of alloy anodes and conversion-type cathodes in all-solid-state batteries, as well as the internal stress damage to the solid electrolyte itself. At the same time, by selecting a silicon anode and conversion-type cathode materials such as S / Se, their high theoretical specific capacity can greatly improve the energy density of all-solid-state batteries, effectively improving the cycle stability, Coulomb efficiency, economy and safety of silicon-sulfur batteries at ultra-high load. Brief Description of the Drawings

[0009] Figure 1 is a schematic diagram of the configuration design of the silicon-sulfur all-solid-state battery in the embodiment of the present invention; Figure 2 is a schematic diagram of the in-situ pressure change of the lithium-silicon all-solid-state half-cell and the lithium-sulfur all-solid-state half-cell in the embodiment of the present invention; Figure 3 is a cross-sectional scanning electron microscope image of the lithium-silicon all-solid-state half-cell after cycling in the embodiment of the present invention; Figure 4 is a top surface scanning electron microscope image of the lithium-silicon all-solid-state half-cell after cycling in the embodiment of the present invention; Figure 5 Schematic diagram of in-situ pressure change of the silicon-sulfur all-solid-state battery in the embodiment of the present invention; Figure 6 Scanning electron microscopy images of the electrode morphology of the silicon-sulfur all-solid-state battery before and after cycling in the embodiment of the present invention; Figure 7 Schematic diagram of charge-discharge curves of the silicon-sulfur all-solid-state battery at different current densities in the embodiment of the present invention; Figure 8 Graph of the 500-cycle long-term cycling performance of the silicon-sulfur all-solid-state battery in the embodiment of the present invention; Figure 9 Schematic diagram of charge-discharge curves of the silicon-sulfur all-solid-state battery (Li x Si||Li4(BH)3I||S) in the embodiment of the present invention; Figure 10 Schematic diagram of charge-discharge curves of the silicon-sulfur all-solid-state battery (Si||LiBH4||Li2S) in the embodiment of the present invention; Figure 11 Schematic diagram of charge-discharge curves of the silicon-sulfur all-solid-state battery (Li x Si||Li6PS5Cl||S) in the embodiment of the present invention; Figure 12 Schematic diagram of the structural design of the silicon-selenium all-solid-state battery in the embodiment of the present invention; Figure 13 X-ray diffraction pattern of the prepared selenium composite cathode in the embodiment of the present invention; Figure 14 Schematic diagram of in-situ pressure change of the lithium-selenium all-solid-state half-cell in the embodiment of the present invention; Figure 15 Schematic diagram of in-situ pressure change of the silicon-selenium all-solid-state battery in the embodiment of the present invention; Figure 16 Schematic diagram of charge-discharge curves of the silicon-selenium all-solid-state battery in the first 20 cycles at 0.1 C in the embodiment of the present invention; Figure 17 Schematic diagram of the rate performance of the silicon-selenium all-solid-state battery in the embodiment of the present invention; Figure 18 Schematic diagram of the long-term cycling performance of the silicon-selenium all-solid-state battery in the embodiment of the present invention; Figure 19 Schematic diagram of charge-discharge curves of the silicon-selenium all-solid-state battery (Li x Si||Li6PS5Cl||Se) in the first 20 cycles at 0.1 C in the embodiment of the present invention; Figure 20 Schematic diagram of charge-discharge curves of the silicon-selenium all-solid-state battery (Li x Si||Li4(BH4)3I||Se) in the first 20 cycles at 0.1 C in the embodiment of the present invention; Figure 21 It is a schematic diagram of the all-solid-state battery structure of the silicon negative electrode and the conversion-type positive electrode of the present invention. Specific embodiments

[0010] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments: Example 1

[0011] As Figure 1 shown, the preparation method of the Li x Si||LiBH4||S all-solid-state battery is as follows: A. The pre-lithiated lithium-silicon alloy sample Li x Si (including but not limited to Li 0.5 Si, LiSi, Li 1.5 Si, Li 1.71 Si, Li2Si, Li 2.33 Si, Li 2.5 Si, Li3Si, Li 3.25 Si, Li 3.5 Si, Li 3.75 Si, Li4Si, Li 4.4 Si), conductive carbon, and solid electrolyte are dynamically formulated according to a + b + c = 1, 5% ≤ a ≤ 95%, 5% ≤ c ≤ 95%, where a, b, and c are the mass ratios of the active material, conductive carbon, and solid electrolyte respectively, and mechanically ground to obtain a Si negative electrode; B. The elemental S, conductive carbon, and solid electrolyte are dynamically formulated according to a + b + c = 1, 5% ≤ a ≤ 95%, 5% ≤ c ≤ 95%, where a, b, and c are the mass ratios of the active material, conductive carbon, and solid electrolyte respectively, and mechanically ground to obtain an S positive electrode; C. The negative electrode material, electrolyte, and positive electrode material are sequentially added to a pressure mold, and a pressure of 20 - 200 MPa is applied externally to complete the assembly of the all-solid-state battery.

[0012] Charge and discharge tests are respectively carried out on the Li-Si and Li-S all-solid-state half-cells: From Figure 2 it can be seen that there are large internal stress changes during the charge and discharge processes of both the Li-Si and Li-S all-solid-state half-cells. Especially in the Li-Si half-cell system, the stress change is particularly obvious, with a maximum approaching 6 MPa; Figure 3 It is a cross-sectional scanning electron microscope image of the lithium-silicon all-solid-state half-cell after cycling. It can be seen from the figure that the solid-state battery assembled based on the present invention can still maintain a dense structure after cycling; From Figure 4It can be seen that based on the Li-Si half-cell system, due to its large internal stress change, cracks appear on the electrode surface after cycling. At the same time, lithium dendrites grow near the cracks, eventually leading to the occurrence of battery short-circuit phenomenon; From Figure 5 It can be seen that in the Si-S all-solid-state battery designed based on the configuration of the present invention, the internal stress remains in a relatively stable state during the cycling process without large fluctuations, effectively avoiding the damage of the internal stress to the battery; Figure 6 Figure 1 is the scanning electron microscope image of the electrode morphology of the above Si-S all-solid-state battery before and after cycling. It can be seen that due to the internal stress remaining in a relatively stable state, the mechanical damage to the battery is greatly alleviated, and there are no obvious cracks and pores on the electrode surface after cycling compared with the state before cycling; Figure 7 Figure 2 is the charge-discharge curve of the above Si-S all-solid-state battery at different current densities. It can be seen that at a high loading (18.1 mg cm -2 ), and a large current density (25.12 mA cm -2 ), the battery can still maintain a specific capacity close to 800 mAh g -1 ; Figure 8 Figure 3 is the long-cycle performance graph of the above Si-S all-solid-state battery. It can be seen that after 500 cycles, the battery can still maintain an areal capacity of 7.6 mAh cm -2 , showing good capacity retention, and the average Coulombic efficiency exceeds 99.8%. Example 2

[0013] As Figure 1 shown, the preparation method of the Li x Si||Li4(BH4)3I||S all-solid-state battery is as follows: A. Prepare the Li4(BH4)3I solid electrolyte by ball milling and heat treatment: The experimental drugs LiBH4 and LiI are stored in a glove box filled with argon. First, weigh LiBH4 and LiI with a molar ratio of 3:1, grind the mixture evenly with a mortar, then transfer it to a stainless steel ball milling jar, and then put stainless steel balls with a diameter of 7 mm. Seal it in the glove box, and then take it out and put it into a planetary ball mill for high-energy ball milling. Set the rotation speed to 400 rpm and the ball milling time to 5 h. After ball milling, take out the powder sample for tablet pressing, and put the pressed block into a heat treatment device. Heat treat it at 140 °C in an argon atmosphere for 2 h to obtain the Li4(BH4)3I solid electrolyte. The above preparation process is carried out in an argon atmosphere; B. In the pressure mold, add the negative electrode material (prepared by the same method as in Example 1), Li4(BH4)3I solid-state electrolyte, and positive electrode material (prepared by the same method as in Example 1) in sequence, and apply an external pressure of 20 - 200 MPa to complete the assembly of the all-solid-state battery.

[0014] Figure 9 For the above all-solid-state battery (Li x Si||Li4(BH4)3I||S), the charge-discharge curve at a rate of 0.1 C is shown. It can be seen that the discharge capacity of the battery is as high as 1659 mAh g -1 , and the Coulomb efficiency reaches 100%. Example 3

[0015] As Figure 1 shown, the preparation method of the Si||LiBH4||Li2S all-solid-state battery is as follows: A. Dynamically mix nano-Si, conductive carbon, and solid-state electrolyte according to a certain mass ratio a + b + c = 1, where 5% ≤ a ≤ 95% and 5% ≤ c ≤ 95%. Here, a, b, and c are the mass ratios of the active material, conductive carbon, and solid-state electrolyte respectively, and mechanically grind to obtain the Si negative electrode composite material.

[0016] B. Dynamically mix Li2S, conductive carbon, and solid-state electrolyte according to a certain mass ratio a + b + c = 1, where 5% ≤ a ≤ 95% and 5% ≤ c ≤ 95%. Here, a, b, and c are the mass ratios of the active material, conductive carbon, and solid-state electrolyte respectively, and mechanically grind to obtain the Li2S positive electrode composite material.

[0017] C. In the pressure mold, add the negative electrode material, electrolyte, and positive electrode material in sequence, and apply an external pressure of 20 - 200 MPa to complete the assembly of the all-solid-state battery.

[0018] Figure 10 For the charge-discharge curve of the above (Si||LiBH4||Li2S) all-solid-state battery at a rate of 0.1 C, it can be seen that the specific capacity can reach 3792 mAh g -1 during the charging process, indicating that Li2S can serve as an effective lithium source supply in this system. Example 4

[0019] As Figure 1 shown, the preparation method of the Li x Si||Li6PS5Cl||S all-solid-state battery is as follows: In a pressure mold, the negative electrode material (prepared in the same way as in Example 1), Li6PS5Cl solid electrolyte, and positive electrode material (prepared in the same way as in Example 1) are sequentially added, and a pressure of 20 - 200 MPa is applied externally to complete the assembly of the all-solid-state battery.

[0020] Figure 11 For the above (Li x Si||Li6PS5Cl||S) all-solid-state battery, the charge-discharge curve at a rate of 0.1 C shows that the capacity can reach 965 mAh g -1 specific capacity during the charging process, and the Coulomb efficiency is as high as 99.37%, indicating that the all-solid-state battery can operate stably under the Li6PS5Cl system. Example 5

[0021] As Figure 12 shown, the preparation method of the Li x Si||LiBH4||Se all-solid-state battery is as follows: A. Se, conductive carbon, and solid electrolyte are dynamically formulated according to the equation a + b + c = 1 (5% ≤ a ≤ 95%, 5% ≤ c ≤ 95%), where a, b, and c represent the mass ratios of the active material, conductive carbon, and solid electrolyte respectively. After mixing and grinding and high-energy ball milling for a certain time, a composite positive electrode material with the active material being Se is obtained; B. In a pressure mold, the negative electrode material (prepared in the same way as in Example 1), electrolyte, and positive electrode material are sequentially added, and a pressure of 20 - 200 MPa is applied externally to complete the assembly of the all-solid-state battery.

[0022] From Figure 13 it can be seen that the composite positive electrode has a strong diffraction peak of Se, proving that the composite positive electrode material with the active material being Se has been successfully prepared; From Figure 14 it can be seen that the stress change inside the lithium-selenium all-solid-state battery during the charge-discharge process is very obvious, and the maximum change is close to 5.25 MPa, which is caused by the volume expansion and contraction of the lithium-selenium battery during the charge-discharge process.

[0023] From Figure 15 it can be seen that the novel silicon-selenium all-solid-state battery system designed in this example greatly relieves the internal stress of the battery, the overall pressure of the battery is relatively stable, and the fluctuation is very small, effectively avoiding the damage of the internal stress to the internal materials and structure of the battery.

[0024] Figure 16 is the charge-discharge curve of the above-prepared silicon-selenium all-solid-state battery in the first 20 cycles at 0.1 C. It can be seen that the battery has a high discharge specific capacity, and the discharge capacity of the battery can still be maintained at 646.71 mAh g after 20 cycles-1 The specific capacity, and the Coulombic efficiency is increased to 99.61%.

[0025] Figure 17 is a schematic diagram of the rate performance of the silicon-selenium all-solid-state battery prepared above. It can be seen that the battery has a high reversible capacity at different rates, showing good rate performance. At a high rate (1 C), the battery capacity can still remain close to 360 mAh g -1 of the specific capacity, and this is the discharge specific capacity when cycling more than 70 times. From this, it can be seen that the all-solid-state silicon-selenium battery prepared above has improved the rate performance and stability of the battery.

[0026] Figure 18 is a schematic diagram of the long-cycle performance of the silicon-selenium all-solid-state battery prepared above. It can be seen that the battery can still maintain a capacity of 393.50 mAh g after 150 cycles -1 and the Coulombic efficiency is stable at about 100%, showing good cycle stability. Example 6

[0027] As Figure 12 shown, the preparation method of the Li x Si||Li6PS5Cl||Se all-solid-state battery is as follows: Add the negative electrode material (prepared in the same way as in Example 1), Li6PS5Cl solid electrolyte, and positive electrode material (prepared in the same way as in Example 5) into the pressure mold, and apply an external pressure of 20 - 200 Mpa to complete the assembly of the all-solid-state battery.

[0028] Figure 19 is a schematic diagram of the charge-discharge curves of the silicon-selenium all-solid-state battery (Li x Si||Li6PS5Cl||Se) at 0.1 C for the first 20 cycles. It can be seen that the discharge capacity of the battery is relatively stable. After 20 cycles, the battery maintains a specific capacity of 508.27 mAh g -1 and the Coulombic efficiency is basically maintained at 99% - 100%. The battery is activated around 10 cycles, and the battery capacity is further improved. All of the above prove that the all-solid-state battery of this system can operate normally and stably under the Li6PS5Cl electrolyte. Example 7

[0029] As Figure 12 shown, the preparation method of the Li x Si||Li4(BH4)3I||Se all-solid-state battery is as follows: Add the anode material (prepared in the same way as in Example 1), Li4(BH4)3I electrolyte material (prepared in the same way as in Example 2), and cathode material (prepared in the same way as in Example 5) into a pressure mold, and apply an external pressure of 20 - 200 Mpa to complete the assembly of the all-solid-state battery.

[0030] Figure 20 is the charge-discharge curve schematic diagram of the above-prepared silicon-selenium all-solid-state battery (Li x Si||Li4(BH4)3I||Se) at 0.1 C for the first 20 cycles. It can be seen that under the Li4(BH4)3I electrolyte, the battery exhibits a very high discharge specific capacity, and the discharge capacity can still be maintained at 585.76 mAh g after 20 cycles. -1 , and the Coulomb efficiency reaches 99.14%, demonstrating good reversibility and cycle stability, proving that this system can also operate stably under the Li4(BH4)3I electrolyte, and the batteries of this system can also be adapted to different solid electrolytes.

[0031] The above-described embodiments are only the preferred embodiments of the present invention. The protection scope of the present invention is not limited thereto. Any equivalent substitution or transformation made by those skilled in the art based on the present invention is within the protection scope of the present invention.

Claims

1. A all-solid-state battery based on a high-performance silicon anode and a conversion-type cathode, characterized in that, The battery is composed of a Si negative electrode, a conversion-type positive electrode, and a solid electrolyte; the active material of the negative electrode is Li x Si alloy, and the active material of the conversion-type positive electrode is a chalcogenide or a metal halide; each electrode includes an active substance, conductive carbon, and a solid electrolyte, and the mass ratios of each part are dynamically adjusted according to a + b + c = 1, 5% ≤ a ≤ 95%, 5% ≤ c ≤ 95%, where a, b, and c are the mass ratios of the active substance, conductive carbon, and solid electrolyte, respectively.

2. The all-solid-state battery based on a high-performance silicon negative electrode and a conversion-type positive electrode according to claim 1, wherein The chalcogenide is S, Li2S, Se, Li2Se, Te, Li2Te, CoS2, CuS, Cu2S, NiS, FeS2, FeS, FeSe, Co3S4, MnS2, CoSe2, CuSe or MnS.

3. The all-solid-state battery based on a high-performance silicon negative electrode and a conversion-type positive electrode according to claim 2, wherein The battery reaction equation is (x / 2)S / Se / Te + Li x Si = Si + (x / 2)Li2S / Li2Se, where 0 < x ≤ 4.

4.

4. The all-solid-state battery based on a high-performance silicon negative electrode and a conversion-type positive electrode according to claim 1, wherein The metal halides are AgF, Br2, LiBr, CuF, AgCl, BiF3, I2, LiI, CuCl2, NiCl2, FeCl3, FeCl2, CoCl2, MnCl2, CuF2, CoF3, NiF2, CoF2, FeF3, FeF2, MnF3, CrF3, VF3 or TiF 3。 5. The all-solid-state battery based on a high-performance silicon negative electrode and a conversion-type positive electrode according to claim 1, wherein, The Li x proportion of pre-lithiated Si in Si includes but is not limited to Li 0.5 Si, LiSi, Li 1.5 Si, Li 1.71 Si, Li2Si, Li 2.33 Si, Li 2.5 Si, Li3Si, Li 3.25 Si, Li 3.5 Si, Li 3.75 Si, Li4Si, Li 4.4 Si.

6. The all-solid-state battery based on a high-performance silicon negative electrode and a conversion-type positive electrode according to claim 1, wherein The solid electrolyte is a lithium borohydride, a lithium sulfide, a lithium oxide, a lithium halide, a lithium-containing polymer or a composite thereof.

7. The all-solid-state battery based on a high-performance silicon negative electrode and a conversion-type positive electrode according to claim 6, characterized in that, The solid electrolyte is a lithium borohydride, a lithium sulfide.

8. The all-solid-state battery based on a high-performance silicon negative electrode and a conversion-type positive electrode according to claim 7, characterized in that, The lithium borohydrides include, but are not limited to, LiBH4, Li4(BH4)3I, Li2B 12 H 12 , Li(CB9H 10 ), Li(CB 11 H 12 ).

9. The all-solid-state battery based on a high-performance silicon negative electrode and a conversion-type positive electrode according to claim 7, characterized in that, The sulfide of lithium is 70Li2S-30P2S5, Li 10 GeP2S 12 , Li6PS5Cl, Li (7-x+y) PS (6-x) Cl (x+y) (0.05 ≤ y ≤ 0.9, -3.0x + 1.8 ≤ y ≤ -3.0x + 5.7), Li6PS5Br, Li6PS5I, Li 10 GeP2S 11.7 O 0.3 , Li 9.54 Si 1.74 P 1.44 S 11.7 Cl 0.3 or Li2Zn 0.5 PS4.

10. The all-solid-state battery based on a high-performance silicon negative electrode and a conversion-type positive electrode according to claim 6, wherein The oxide of lithium is Li 6.4 La3Zr 1.4 Ta 0.6 O 12 , Li7La3Zr2O 12 or Li 1.3 Al 0.3 Ti 1.7 (PO4)3.

11. The all-solid-state battery based on a high-performance silicon anode and a conversion-type cathode according to claim 6, characterized in that, The lithium halide is Li3YCl6, Li3ErCl6, Li3InCl6, Li3YBr6, Li3InBr6, Li3ScCl6 or Li 1.75 ZrCl 4.75 O 0.5 .

12. The all-solid-state battery based on a high-performance silicon anode and a conversion-type cathode according to claim 6, characterized in that, The polymer backbone is PEO, PMMA, PAN, PVC, PVDF or PVDF-HFP.

13. The all-solid-state battery based on a high-performance silicon negative electrode and a conversion-type positive electrode according to claim 1, characterized in that, The battery is assembled in the form of a button cell, a soft-packaged cell or assembled with a special pressure mold.

14. The dynamic compensation method for volume expansion of an all-solid-state battery based on a high-performance silicon negative electrode and a conversion-type positive electrode according to any one of claims 1-13, characterized in that By matching a conversion-type cathode material with a Si anode material, and taking advantage of the large volume expansion and contraction of the conversion-type cathode material during battery cycling to compensate for part of the volume change generated by the Si anode and reduce the internal stress change of the battery, thereby avoiding mechanical damage to the solid electrolyte.

15. The dynamic compensation method for volume expansion of all-solid-state battery based on high-performance silicon negative electrode and conversion-type positive electrode according to claim 14, characterized in that On the negative electrode side, lithium ions are transferred from Li x The lithium ions are released from Si and the volume shrinks; the lithium ions and active materials on the positive electrode combine to form lithium sulfide compounds or halides, and the volume expands; the volume changes of the positive and negative electrodes compensate each other, thereby achieving a dynamic balance of the overall volume of the solid-state battery, and the charging process is the same.

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