Lithium electrode with interface layer of inorganic-rich hybrid solid-state electrolyte constructed by one-step liquid siloxane plasma method, preparation method and application thereof

Abstract

This invention belongs to the field of lithium metal electrode technology, and relates to a lithium electrode with an inorganic-rich hybrid solid electrolyte interface layer constructed in one step using liquid siloxane plasma, its preparation method, and its application. The preparation method uses a lithium sheet as a substrate and methyl liquid siloxane as a plasma source to construct a hybrid inorganic-rich solid electrolyte interface layer in one step using plasma, thus obtaining a composite lithium metal electrode. In this invention, an inorganic-rich SEI layer, comprising lithium silicate and lithium carbonate, is constructed in one step using plasma. The lithium silicate portion enhances the flexibility and mechanical stability of the SEI layer, directly isolating side reactions between metallic lithium and the electrolyte; the lithium carbonate portion increases the Li content at the uniform interface. + Flow rate. Therefore, the lithium electrode of this invention exhibits good cycle stability, rate performance, and coulombic efficiency. Meanwhile, the preparation method provided by this invention is simple, rapid, efficient, convenient, and easy to control, contributing to the development of artificial solid-state electrolyte interface layers for lithium metal batteries.

Description

Technical Field

[0001] This invention relates to the field of lithium metal battery technology, specifically to a lithium electrode with an inorganic hybrid solid electrolyte interface layer constructed by a one-step liquid siloxane plasma method, and its preparation method and application. Background Technology

[0002] With the advocacy of "carbon peaking" and "carbon neutrality," clean energy has developed rapidly in recent years. Lithium-ion batteries, due to their high safety, high energy density, and long cycle life, have become widely used energy storage devices. However, graphite, a commonly used material for the negative electrode of lithium-ion batteries, has a theoretical capacity of only 372 mAh / g, which is insufficient to meet the demands of energy storage batteries. Therefore, in recent years, researchers have been actively searching for materials that can replace graphite as the negative electrode for lithium-ion batteries. Lithium metal, with its extremely high theoretical capacity (3860 mAh / g), extremely low redox potential (-3.04 V), and relatively low density (0.534 g / cm³), is a promising alternative. 3 It has become an ideal alternative to commercial graphite materials.

[0003] However, lithium metal batteries using lithium metal as the anode still suffer from a series of problems, including unlimited volume expansion, lithium dendrite growth, and SEI layer cracking. Among these, constructing a stable SEI layer is crucial for the development of next-generation high-energy-density lithium metal batteries. It is well known that the natural SEI layer grown on a Li metal anode consists of an inner inorganic layer (such as Li₂O, LiOH, and Li₂CO₃) and an outer organic layer (ROCO₂Li, ROLi, and RCOO₂Li). The naturally formed SEI layer can optimize the interface between lithium metal and the electrolyte; however, it is inherently non-uniform and fragile, easily leading to performance degradation and battery failure. For the inner inorganic SEI, it possesses advantages such as excellent interfacial energy and superior ionic conductivity, which can accelerate the lateral diffusion of lithium ions along the SEI / Li interface, effectively forming a uniform ion flux, thereby suppressing dendrite formation and improving the stability of the lithium metal anode. In recent years, lithium silicate-based materials have attracted much attention as promising artificial solid electrolyte interphase (SEI) layers for lithium metal batteries. Compared to traditional SEI components (such as LiF, Li3N, and polymers), lithium silicate (Li... x SiO yLithium silicate-based materials possess unique electrochemical stability, mechanical robustness, and moderate ionic conductivity. These superior properties stem from three inherent characteristics: (1) serving as an electrochemically inert yet structurally stable framework; (2) exhibiting excellent mechanical strength, capable of withstanding volume fluctuations during cycling; and (3) establishing an efficient lithium-ion conduction pathway. These advantages make lithium silicate-based materials particularly suitable for constructing high-performance artificial SEI layers, thereby significantly improving the cycling stability and structural integrity of lithium metal anodes. However, the preparation of lithium silicate-based SEI layers is relatively difficult, and their electrochemical performance is not outstanding, which hinders the commercialization of artificial SEI layers.

[0004] Based on this, the present invention proposes a one-step rapid construction method for a lithium silicate-rich inorganic hybrid artificial solid electrolyte interface layer composite electrode using liquid silane plasma technology under relatively mild conditions. This method allows for the control of the chemical composition of the artificial solid electrolyte interface layer, thereby preparing a high-performance lithium metal anode. Summary of the Invention

[0005] The purpose of this invention is to address a series of problems existing in the solid electrolyte interface layer in lithium metal battery systems, and to provide a composite lithium metal electrode and its preparation method for constructing an inorganic hybrid solid electrolyte interface layer in one step using liquid siloxane plasma. This method has the advantage of alleviating volume expansion and lithium dendrite growth during lithium metal deposition. At the same time, the artificial solid electrolyte interface layer can be controlled to prepare artificial SEI layers of different thicknesses by adjusting parameters such as reaction time and radio frequency power, which can further expand the application range.

[0006] The technical solution adopted by this invention to solve its technical problem is:

[0007] This invention provides a method for preparing a composite lithium metal electrode by constructing a rich inorganic hybrid solid electrolyte interface layer in one step using liquid siloxane plasma. The method uses a lithium sheet as a substrate and methyl liquid siloxane as a plasma source to construct the hybrid solid electrolyte interface layer in one step through plasma reaction, thereby obtaining the composite lithium metal electrode.

[0008] Preferably, the preparation method specifically includes the following steps:

[0009] (1) Methyl liquid siloxane is sealed and loaded into the liquid source device, and lithium sheet is sealed in the plasma device;

[0010] (2) Connect the plasma device and the liquid source device to the plasma generator, then evacuate the plasma device and introduce methyl liquid siloxane vapor from the liquid source device to control the amount of vapor introduced, thereby achieving the purpose of controlling the preparation of artificial SEI layers of different thicknesses.

[0011] (3) By adjusting the radio frequency power to control the plasma, after ignition, the methyl liquid siloxane plasma will react with Li. After a certain reaction time, the radio frequency power is turned off to form a composite lithium metal anode (LiSiO-Li) with a corresponding inorganic hybrid artificial solid electrolyte interface layer.

[0012] The following are preferred technical solutions of the present invention:

[0013] In step (1), the step is carried out under a protective atmosphere, which is at least one of helium and argon; more preferably, the operation carried out under a protective atmosphere can be carried out in a glove box filled with argon.

[0014] In step (1), the lithium sheet can be a conventional commercial lithium sheet, and its size is suitable for placement in the device, preferably with a diameter of 15 mm. This invention uses metallic lithium sheets as the research object, constructing an organic-inorganic artificial interface layer on the surface of the metallic lithium. More preferably, the amount of methyl liquid siloxane is 1-10 mL.

[0015] Preferably, in step (1), the methyl liquid siloxane includes at least one of methyl liquid siloxanes such as octamethyltrisiloxane, polydimethylsiloxane, methyl vinylcyclosiloxane, and decamethylcyclopentasiloxane for constructing the interface layer; more preferably, it is octamethyltrisiloxane (MDM).

[0016] Preferably, in step (2), the vacuum level is 1-10 Pa after evacuation, and the vacuum level of the system after introducing methyl liquid siloxane vapor is preferably 2-25 Pa.

[0017] Preferably, in step (3), the reaction conditions are: radio frequency power maintained at 100-140W, vacuum degree at 2-25Pa, and reaction time after ignition at 30-90s; more preferably, radio frequency power at 110-125W, vacuum degree at 10-20Pa, and reaction time at 30-90s; even more preferably, radio frequency power at 120W, vacuum degree at 20Pa, and reaction time at 30-60s. Too short a time and too low a power will prevent the siloxane from reacting with the lithium metal. Conversely, the lithium metal will be damaged because it cannot withstand the violent reaction. At the same time, a vacuum degree below 2Pa will prevent ignition and plasma reaction, while a vacuum degree above 25Pa will damage the lithium sheet due to the excessively violent reaction.

[0018] Preferably, in step (3), the formed inorganic hybrid artificial solid electrolyte interphase (SEI) layer includes lithium silicate and lithium carbonate, and the layer thickness is preferably 5-10 μm.

[0019] The present invention also provides a composite lithium electrode with an inorganic hybrid solid electrolyte interface layer constructed by the above-described liquid siloxane plasma one-step method.

[0020] This invention also provides an application of the composite lithium electrode constructed by the above-mentioned liquid siloxane plasma one-step method for constructing an inorganic hybrid solid electrolyte interface layer in the field of lithium batteries.

[0021] In this invention, the aforementioned one-step methyl liquid siloxane plasma method enables rapid in-situ construction of an inorganic hybrid solid electrolyte interface layer (SEI) on the lithium metal surface. To date, there have been no reports on the application of methyl liquid siloxane plasma in lithium metal anodes. The lithium silicate in the SEI layer prepared by methyl liquid siloxane adheres firmly to the Li foil surface, establishing a dense barrier to prevent air diffusion. Simultaneously, the good adhesion between the SEI layer and the Li metal substrate prevents SEI layer cracking and detachment, further reducing side reactions between the active Li metal and the electrolyte. Furthermore, the effective combination of lithium carbonate and lithium silicate mitigates volume changes during lithium metal deposition, resulting in a uniform Li interface. + The flow rate is reduced, suppressing the formation of lithium dendrites. Therefore, lithium sheets modified by methyl liquid siloxane plasma exhibit superior electrochemical performance and safety, providing more possibilities for the commercial application of lithium metal batteries.

[0022] Meanwhile, the preparation method of this invention allows for the controllable preparation of artificial SEI layers of varying thicknesses by adjusting parameters such as reaction time and radio frequency power. Thinner SEI films can promote rapid lithium-ion transport, thereby improving the charging and discharging speed of the battery. SEI films of moderate thickness can effectively isolate direct contact between the electrode surface and the electrolyte, preventing excessive electrolyte decomposition and electrode corrosion. However, excessively thick SEI films may affect the ion diffusion rate, leading to a decrease in battery performance. Therefore, an SEI film of appropriate thickness can balance the transport efficiency of ions and electrons, while protecting the battery electrodes and improving battery performance. Since different thicknesses of SEI have different effects on ion and electron transport, and different battery systems have different requirements for ion and electron transport, it is necessary to prepare SEI layers of different thicknesses according to different needs. The plasma preparation method provided by this invention can precisely control the thickness of the SEI layer, making the prepared lithium metal anode material highly reproducible and beneficial for the commercialization of artificial SEI layers.

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

[0024] The liquid siloxane plasma-enhanced chemical vapor deposition method for constructing an inorganic hybrid SEI lithium metal anode is prepared by a single reaction of liquid-source plasma with metallic lithium. Specifically, the lithium silicate SEI layer enhances the flexibility and mechanical stability of the SEI layer, directly isolating side reactions between metallic lithium and the electrolyte; the lithium carbonate SEI layer increases the Li content at the uniform interface. +Flow rate. In addition, the constructed inorganic-rich hybrid SEI layer can achieve nanoscale control of its thickness based on conditions such as reaction time.

[0025] In this invention, an inorganic-rich hybrid artificial interface layer acts as a physical barrier, directly isolating the side reactions between metallic lithium and the electrolyte. The excellent mechanical properties of this interface layer effectively suppress the growth of lithium dendrites. Therefore, this composite anode exhibits excellent cycle stability, rate performance, and coulombic efficiency, and has broad market application prospects.

[0026] Meanwhile, the preparation method described in this invention is simple, fast, efficient, convenient, and easy to control, which helps to promote the development of artificial solid electrolyte interface layers for lithium metal batteries. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the MDM liquid silane plasma-modified lithium sheet in Example 1;

[0028] Figure 2 The TEM results are from Example 1;

[0029] Figure 3 Cycle performance diagrams (1 mA / cm²) of the coin cell symmetric batteries assembled in Example 1 and Comparative Example 4. 2 Current density, 1mAh / cm 2 capacity);

[0030] Figure 4 The rate performance diagrams (0.5, 1, 3, 5 mA / cm) of the coin cell symmetric batteries assembled in Example 1 and Comparative Example 4 are shown. 2 Current density, 1mAh / cm 2 capacity);

[0031] Figure 5 The coulombic efficiency diagrams are for the coin cells assembled in Example 1 and Comparative Example 4.

[0032] Figure 6 Scanning electron microscope (SEM) images of bare lithium in Comparative Example 4 and Example 1;

[0033] Figure 7 These are scanning electron microscope (SEM) images of bare lithium in Comparative Example 4 and Example 1 after 10 cycles.

[0034] Figure 8 This is a profile of the sputtering depth of each secondary ion in the TOF-SIM in Example 1;

[0035] Figure 9 The image shown is a three-dimensional reconstruction of a selected species in TOF-SIM in Example 1. Detailed Implementation

[0036] To facilitate understanding, the technical solutions and implementation methods of the present invention will be further described clearly, completely, and in detail below through specific embodiments and in conjunction with the accompanying drawings. It should be understood that the embodiments described herein are implemented based on the technical solutions of the present invention, providing detailed implementation methods and specific operating procedures, but are only some embodiments of the present invention, not all embodiments. The specific implementation methods described are limited to illustrating and explaining the present invention and do not limit the present invention. Based on the embodiments of the present invention, all other implementation methods obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0037] Unless otherwise specified, the experimental methods and conditions used in the following embodiments are conventional methods and conditions. The materials, reagents, instruments, and equipment used in the embodiments, unless otherwise specified, are all conventional substances or equipment known to those skilled in the art and are commercially available. The reaction conditions described in the invention can all achieve the reactions and obtain the desired products. Due to space limitations, only some embodiments are listed below to further illustrate the advantages of the technical solution of the present invention.

[0038] Example 1

[0039] An appropriate amount of octamethyltrisiloxane (MDM) is loaded into the liquid source device inside an argon-filled glove box. Simultaneously, a 15mm commercial lithium sheet is sealed inside the plasma equipment within the argon-filled glove box. The plasma equipment is then transferred outside the glove box. Copper rings are attached to both ends of the plasma equipment, and the copper rings are connected to the generator of the RF power supply using wires. The plasma equipment is then evacuated to 1-10 Pa (preferably 2 Pa in this embodiment), and MDM vapor is introduced. The RF power switch is turned on, and the RF power is adjusted to 120W, while maintaining the vacuum level inside the device at 20 Pa. After ignition, the liquid silane MDM plasma reacts with Li to form a Li₂SiO₃-Li₂CO₃-rich inorganic hybrid solid electrolyte interphase (SEI). After 30 seconds of reaction, the RF power supply is turned off, yielding an MDM-Li anode.

[0040] Example 2

[0041] An appropriate amount of octamethyltrisiloxane (MDM) was loaded into the liquid source device inside an argon-filled glove box. Simultaneously, a 15mm commercial lithium sheet was sealed inside the plasma equipment within the argon-filled glove box. The plasma equipment was then transferred outside the glove box. Copper rings were connected to both ends of the plasma equipment, and the copper rings were connected to the generator of the RF power supply using wires. The plasma equipment was then evacuated to a vacuum level of 2 Pa, and MDM vapor was introduced. The RF power switch was turned on, and the RF power was adjusted to 120W, while maintaining the vacuum level inside the device at 20 Pa. After ignition, the liquid silane MDM plasma reacted with Li to form a Li₂SiO₃-Li₂CO₃-rich inorganic hybrid artificial solid electrolyte interphase (SEI). After 60 seconds of reaction, the RF power supply was turned off, yielding the MDMi-Li anode.

[0042] Example 3

[0043] An appropriate amount of octamethyltrisiloxane (MDM) was loaded into the liquid source device inside an argon-filled glove box. Simultaneously, a 15mm commercial lithium sheet was sealed inside the plasma equipment within the argon-filled glove box. The plasma equipment was then transferred outside the glove box. Copper rings were attached to both ends of the plasma equipment and connected to the generator of the RF power supply using wires. The plasma equipment was then evacuated to a vacuum level of 2 Pa, and MDM vapor was introduced. The RF power switch was turned on, and the RF power was adjusted to 120W, while maintaining the vacuum level inside the device at 20 Pa. After ignition, the liquid silane MDM plasma reacted with Li to form a Li₂SiO₃-Li₂CO₃-rich inorganic hybrid artificial solid electrolyte interphase (SEI). After 90 seconds of reaction, the RF power supply was turned off, yielding the MDMi-Li anode.

[0044] Example 4

[0045] An appropriate amount of octamethyltrisiloxane (MDM) was loaded into the liquid source device inside an argon-filled glove box. Simultaneously, a 15mm commercial lithium sheet was sealed inside the plasma equipment within the argon-filled glove box. The plasma equipment was then transferred outside the glove box. Copper rings were connected to both ends of the plasma equipment, and wires were used to connect the copper rings to the generator of the RF power supply. The plasma equipment was then evacuated to a vacuum level of 2 Pa, and MDM vapor was introduced. The RF power switch was turned on, and the RF power was adjusted to 130W, while maintaining the vacuum level inside the device at 20 Pa. After ignition, the liquid silane MDM plasma reacted with Li to form a Li₂SiO₃-Li₂CO₃-rich inorganic hybrid artificial solid electrolyte interphase (SEI). After 30 seconds of reaction, the RF power was turned off, yielding the MDMi-Li anode.

[0046] Example 5

[0047] An appropriate amount of octamethyltrisiloxane (MDM) was loaded into the liquid source device inside an argon-filled glove box. Simultaneously, a 15mm commercial lithium sheet was sealed inside the plasma equipment within the argon-filled glove box. The plasma equipment was then transferred outside the glove box. Copper rings were attached to both ends of the plasma equipment and connected to the generator of the RF power supply using wires. The plasma equipment was then evacuated to a vacuum level of 2 Pa, and MDM vapor was introduced. The RF power switch was turned on, and the RF power was adjusted to 130W, while maintaining the vacuum level inside the device at 20 Pa. After ignition, the liquid silane MDM plasma reacted with Li to form a Li₂SiO₃-Li₂CO₃-rich inorganic hybrid artificial solid electrolyte interphase (SEI). After 60 seconds of reaction, the RF power supply was turned off, yielding the MDMi-Li anode.

[0048] Example 6

[0049] An appropriate amount of octamethyltrisiloxane (MDM) was loaded into the liquid source device inside an argon-filled glove box. Simultaneously, a 15mm commercial lithium sheet was sealed inside the plasma equipment within the argon-filled glove box. The plasma equipment was then transferred outside the glove box. Copper rings were connected to both ends of the plasma equipment, and the copper rings were connected to the generator of the RF power supply with wires. The plasma equipment was then evacuated to a vacuum level of 2 Pa, and MDM vapor was introduced. The RF power switch was turned on, and the RF power was adjusted to 130W, while maintaining the vacuum level inside the device at 20 Pa. After ignition, the liquid silane MDM plasma reacted with Li to form a Li₂SiO₃-Li₂CO₃-rich inorganic hybrid artificial solid electrolyte interphase (SEI). After 90 seconds of reaction, the RF power supply was turned off, yielding the MDMi-Li anode.

[0050] Example 7

[0051] An appropriate amount of octamethyltrisiloxane (MDM) was loaded into the liquid source device inside an argon-filled glove box. Simultaneously, a 15mm commercial lithium sheet was sealed inside the plasma equipment within the argon-filled glove box. The plasma equipment was then transferred outside the glove box. Copper rings were connected to both ends of the plasma equipment, and the copper rings were connected to the generator of the RF power supply using wires. The plasma equipment was then evacuated to a vacuum level of 2 Pa, and MDM vapor was introduced. The RF power switch was turned on, and the RF power was adjusted to 140W, while maintaining the vacuum level inside the device at 20 Pa. After ignition, the liquid silane MDM plasma reacted with Li to form a Li₂SiO₃-Li₂CO₃-rich inorganic hybrid artificial solid electrolyte interphase (SEI). After 30 seconds of reaction, the RF power supply was turned off, yielding the MDMi-Li anode.

[0052] Example 8

[0053] An appropriate amount of octamethyltrisiloxane (MDM) was loaded into the liquid source device inside an argon-filled glove box. Simultaneously, a 15mm commercial lithium sheet was sealed inside the plasma equipment within the argon-filled glove box. The plasma equipment was then transferred outside the glove box. Copper rings were attached to both ends of the plasma equipment and connected to the generator of the RF power supply using wires. The plasma equipment was then evacuated to a vacuum level of 2 Pa, and MDM vapor was introduced. The RF power switch was turned on, and the RF power was adjusted to 140W, while maintaining the vacuum level inside the device at 20 Pa. After ignition, the liquid silane MDM plasma reacted with Li to form a Li₂SiO₃-Li₂CO₃-rich inorganic hybrid artificial solid electrolyte interlayer (SEI). After 60 seconds of reaction, the RF power supply was turned off, yielding the MDMi-Li anode.

[0054] Example 9

[0055] An appropriate amount of octamethyltrisiloxane (MDM) was loaded into the liquid source device inside an argon-filled glove box. Simultaneously, a 15mm commercial lithium sheet was sealed inside the plasma equipment within the argon-filled glove box. The plasma equipment was then transferred outside the glove box. Copper rings were connected to both ends of the plasma equipment, and the copper rings were connected to the generator of the RF power supply using wires. The plasma equipment was then evacuated to a vacuum level of 2 Pa, and MDM vapor was introduced. The RF power switch was turned on, and the RF power was adjusted to 140W, while maintaining the vacuum level inside the device at 20 Pa. After ignition, the liquid silane MDM plasma reacted with Li to form a Li₂SiO₃-Li₂CO₃-rich inorganic hybrid artificial solid electrolyte interphase (SEI). After 90 seconds of reaction, the RF power supply was turned off, yielding the MDMi-Li anode.

[0056] Example 10

[0057] An appropriate amount of octamethyltrisiloxane (MDM) was loaded into the liquid source device inside an argon-filled glove box. Simultaneously, a 15mm commercial lithium sheet was sealed inside the plasma equipment within the argon-filled glove box. The plasma equipment was then transferred outside the glove box. Copper rings were attached to both ends of the plasma equipment and connected to the generator of the RF power supply using wires. The plasma equipment was then evacuated to a vacuum level of 2 Pa, and MDM vapor was introduced. The RF power switch was turned on, and the RF power was adjusted to 120W, while maintaining the vacuum level inside the device at 10 Pa. After ignition, the liquid silane MDM plasma reacted with Li to form a Li₂SiO₃-Li₂CO₃-rich inorganic hybrid artificial solid electrolyte interphase (SEI). After 30 seconds of reaction, the RF power supply was turned off, yielding the MDMi-Li anode.

[0058] Example 11

[0059] An appropriate amount of octamethyltrisiloxane (MDM) was loaded into the liquid source device inside an argon-filled glove box. Simultaneously, a 15mm commercial lithium sheet was sealed inside the plasma equipment within the argon-filled glove box. The plasma equipment was then transferred outside the glove box. Copper rings were connected to both ends of the plasma equipment, and wires were used to connect the copper rings to the generator of the RF power supply. The plasma equipment was then evacuated to a vacuum level of 2 Pa, and MDM vapor was introduced. The RF power switch was turned on, and the RF power was adjusted to 120W, while maintaining the vacuum level inside the device at 30 Pa. After ignition, the liquid silane MDM plasma reacted with Li to form a Li₂SiO₃-Li₂CO₃-rich inorganic hybrid artificial solid electrolyte interlayer (SEI). After 30 seconds of reaction, the RF power was turned off, yielding the MDMi-Li anode.

[0060] Example 12

[0061] An appropriate amount of polydimethylsiloxane (PMD) was loaded into the liquid source device inside an argon-filled glove box. Simultaneously, a 15mm commercial lithium sheet was sealed inside the plasma equipment within the argon-filled glove box. The plasma equipment was then transferred outside the glove box. Copper rings were connected to both ends of the plasma equipment, and wires were used to connect the copper rings to the generator of the RF power supply. The plasma equipment was then evacuated to a vacuum level of 2 Pa, and PMD vapor was introduced. The RF power switch was turned on, and the RF power was adjusted to 120W, while maintaining the vacuum level inside the device at 20 Pa. After ignition, the plasma from the liquid silane MDM reacted with Li to form a Li₂SiO₃-Li₂CO₃-rich inorganic hybrid artificial solid electrolyte interphase (SEI). After 30 seconds of reaction, the RF power was turned off, yielding a LiSiO₃-Li anode.

[0062] Example 13

[0063] A suitable amount of methylvinylcyclosiloxane (MDM) was loaded into the liquid source device inside an argon-filled glove box. Simultaneously, a 15mm commercial lithium sheet was sealed inside the plasma equipment within the argon-filled glove box. The plasma equipment was then transferred outside the glove box. Copper rings were connected to both ends of the plasma equipment, and wires were used to connect the copper rings to the generator of the RF power supply. The plasma equipment was then evacuated to a vacuum level of 2 Pa, and methylvinylcyclosiloxane vapor was introduced. The RF power switch was turned on, and the RF power was adjusted to 120W, while maintaining the vacuum level inside the device at 20 Pa. After ignition, the plasma from the liquid silane MDM reacted with Li to form a Li₂SiO₃-Li₂CO₃-rich inorganic hybrid artificial solid electrolyte interphase (SEI). After 30 seconds of reaction, the RF power was turned off, yielding a LiSiO₃-Li anode.

[0064] Example 14

[0065] An appropriate amount of decamethylcyclopentasiloxane was loaded into the liquid source device inside an argon-filled glove box. Simultaneously, a 15mm commercial lithium sheet was sealed inside the plasma equipment within the argon-filled glove box. The plasma equipment was then transferred outside the glove box. Copper rings were connected to both ends of the plasma equipment, and the copper rings were connected to the generator of the RF power supply using wires. The plasma equipment was then evacuated to a vacuum level of 2 Pa, and decamethylcyclopentasiloxane vapor was introduced. The RF power switch was turned on, and the RF power was adjusted to 120W, while maintaining the vacuum level inside the device at 20 Pa. After ignition, the plasma of liquid silane MDM reacted with Li to form a Li₂SiO₃-Li₂CO₃-rich inorganic hybrid artificial solid electrolyte interphase (SEI). After 30 seconds of reaction, the RF power supply was turned off, yielding a LiSiO₃-Li anode.

[0066] Comparative Example 1

[0067] A 15mm commercial lithium sheet was placed in an appropriate amount of octamethyltrisiloxane (MDM) in an argon-filled glove box. After reacting for 30 seconds, a LiSiO-Li anode was obtained.

[0068] Comparative Example 2

[0069] A 15mm commercial lithium sheet was placed in an appropriate amount of octamethyltrisiloxane (MDM) in an argon-filled glove box. After reacting for 60 seconds, a LiSiO-Li anode was obtained.

[0070] Comparative Example 3

[0071] A 15mm commercial lithium sheet was placed in an appropriate amount of octamethyltrisiloxane (MDM) in an argon-filled glove box. After reacting for 90 seconds, a LiSiO-Li anode was obtained.

[0072] Comparative Example 4

[0073] A 15mm commercial lithium sheet was used as the P-Li anode inside an argon-filled glove box.

[0074] Performance testing

[0075] The LiSiO-Li prepared in Examples 1-14 and Comparative Examples 1-3, along with the bare lithium P-Li anode of Comparative Example 4, were assembled into coin-type symmetrical batteries in an argon-atmosphere glove box for electrochemical testing. The electrolyte was 1 mol / L LiTFSI / DOL:FEC (1:1 volume ratio, DOL: 1,3-dioxolane; FEC: fluoroethylene carbonate) with 2 wt% LiNO3 added, and the separator was a Celgard 2500 type. The batteries were assembled in the following order: positive electrode shell, LiSiO-Li, electrolyte, separator, LiSiO-Li, and negative electrode shell, and then sealed using a sealing machine. After the batteries were allowed to stand for 24 hours, electrochemical tests were performed using a Xinwei electrochemical workstation. All electrochemical tests were conducted at 30°C, primarily constant current charge-discharge tests. The constant current charge-discharge tests mainly included cycle life and coulombic efficiency. The current density was 1 mA / cm². 2 Capacity 1mAh / cm 2 The battery's long-cycle performance was tested under the following conditions; the cycle time ended when the voltage of the symmetrical battery showed a significant increasing trend during the cycle.

[0076] The performance test results are as follows:

[0077]

[0078]

[0079] Figure 1 This is a photograph of the MDM liquid silane plasma-modified lithium sheet from Example 1. Figure 2 The TEM results are from Example 1; Figure 3 Cycle performance diagrams (1 mA / cm²) of coin symmetric cells assembled from MDM liquid silane plasma-modified materials in Example 1 and coin symmetric cells assembled from pure lithium in Comparative Example 4P-Li. 2 Current density, 1mAh / cm 2 capacity); Figure 5 The coulombic efficiency diagrams are shown for the coin half-cell assembled after MDM liquid silane plasma modification in Example 1 and the coin symmetric cell assembled with pure lithium in the comparative example 4P-Li.

[0080] Depend on Figure 2 TEM and Figure 8 and Figure 9As can be seen, the SEI film is composed of Li₂SiO₃ and Li₂CO₃, and no organic matter was observed. This is significantly different from the conventional organic SEI layers obtained by immersing lithium sheets in liquid siloxanes (such as Comparative Examples 1-3). In the SEI layer obtained by this invention, the Li₂SiO₃ portion enhances the flexibility and mechanical stability of the SEI layer. Since Li₂SiO₃ has been proven to possess strong mechanical properties and interfacial stability, it has been successfully applied to improve the adhesion of composite materials. The Li₂CO₃ portion is used for Li₂ at the uniform interface. + Traffic. Based on the data in the table, and combined with... Figure 3 and 5 As can be seen, after 10 cycles, the coulombic efficiency of the battery in Example 1 is as high as 99.8% or more. This demonstrates that the SEI@Li composite material exhibits strong cycle stability and excellent rate performance. When SEI@Li is assembled alone into a lithium-lithium symmetric battery, at 1 mA / cm²... 2 Current density 1mAh / cm 2 Under high-capacity cycling conditions, it can cycle stably for 689 hours with a stable overpotential of approximately 40.9 mV, indicating that SEI@Li has good cycling stability. It can also suppress the growth of lithium dendrites.

[0081] The rate performance of a lithium-lithium symmetric battery assembled from SEI@Li was tested at different current densities. Figure 4 Rate performance graphs (0.2, 0.5, 1, 2, 5 mA / cm²) of the coin cell assembled after plasma modification with MDM liquid silane in Example 1 and the coin cell assembled with pure lithium in the comparative example 4P-Li. 2 Current density, 1mAh / cm 2 (Capacity). It can be obtained from... Figure 4 As can be seen, the bare lithium in Example 1 has a smaller overpotential than that in Comparative Example 4 at all current densities, demonstrating the superior rate performance of SEI@Li. Figure 6 Scanning electron microscope (SEM) images of bare lithium in Comparative Example 4 and Example 2; Figure 7 The images are SEM images of bare lithium in Comparative Example 4 and Example 2 after 150 cycles. It can be seen from the SEM images of bare lithium and Example 2 before and after cycling that the lithium dendrites formed in Example 2 after cycling are smoother and there are significantly fewer lithium dendrites than those formed in bare lithium after cycling. This indicates that SEI@Li can better resist the formation of lithium dendrites and has better mechanical properties.

[0082] The analysis of the above tables shows that when the RF power is outside the 120-125W range, such as 130W in Examples 4-6 and 140W in Examples 7-9, although SEI@Li can be formed, its electrochemical performance, such as cycle stability, overpotential, and coulombic efficiency, is slightly inferior to that of Examples 1-3 and Example 10. Comparing Examples 11 and 10, it can be seen that the vapor injection rate can affect the thickness of the SEI layer, but the comparison results also show that the electrochemical performance is not high. This indicates that maintaining the RF power at 110-125W, a vacuum degree of 2-20Pa during the reaction, and a ignition reaction time of 30-90s are further optimized conditions. It is shown that SEI@Li formed within this range has better cycle stability and can suppress the growth of lithium dendrites. Furthermore, the experimental data from Comparative Examples 1-3 show that SEI@Li formed within the same time range has better electrochemical performance, thus demonstrating the superiority of the plasma-constructed lithium silicate-rich hybrid inorganic SEI layer of this invention. Meanwhile, Examples 12-14 show that the method of the present invention is applicable to a variety of methyl liquid siloxanes, and can obtain lithium electrodes with SEI layers that have excellent electrochemical performance.

[0083] During battery charging and discharging, the volume of the lithium metal anode undergoes significant changes, leading to the rupture of the natural SEI film. The ruptured SEI film promotes lithium dendrite growth, causing battery failure. To address this issue, researchers typically employ strategies such as electrolyte additives, three-dimensional current collectors, solid electrolytes, and lithium anode surface modification. Among these methods, surface modification is considered an effective approach. This is because lithium metal surface modification can provide a physical barrier, and the SEI film is extremely thin, resulting in negligible impact on the system's weight and volume.

[0084] This invention achieves SEI layer enhancement and improved air stability by modifying lithium metal with methyl liquid siloxane. Siloxane molecules are recombined onto the lithium foil surface and assembled into a thin and dense Li2SiO3-Li2CO3-rich inorganic hybrid solid electrolyte interphase (SEI) layer.

[0085] The inorganic lithium silicate layer of the SEI layer can improve the mechanical stability of the lithium metal anode and inhibit the growth of lithium dendrites. The expansion phenomenon of the SEI layer on the lithium anode: The degree of SEI swelling is related to the electrochemical performance of the lithium anode; inorganic lithium silicate SEI can improve the electrochemical performance of the lithium anode while exhibiting less SEI swelling. The lithium carbonate interface can promote the exchange of Li+ between the electrolyte and the Li interface. + It facilitates the transport of substances and promotes reversible electrochemical reactions in the full cell.

[0086] A one-step methyl liquid siloxane plasma method was used to rapidly construct an inorganic-rich hybrid solid electrolyte interface layer on the lithium metal surface in situ. The effective combination of the lithium silicate inorganic layer and the lithium carbonate inorganic layer can mitigate the volume change during the lithium metal deposition process, and the Li at the uniform interface... + The flow rate is reduced, suppressing the formation of lithium dendrites. Therefore, the lithium foil modified by methyl liquid siloxane plasma exhibits superior electrochemical performance and safety, making commercial applications of lithium metal batteries possible. Electrochemical tests show that the methyl liquid siloxane plasma-modified lithium metal anode material of this invention has excellent cycle stability and capacity retention.

[0087] The solid electrolyte interface layer formed in situ by plasma in methyl liquid siloxane of this invention possesses excellent mechanical strength and electrochemical stability, and can suppress the growth of lithium dendrites. It has broad application prospects in fields such as small mobile electronic devices, electric vehicles, solar power generation, and aerospace.

[0088] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any way. Other variations and modifications may be made without departing from the technical solutions described in the claims.

Claims

1. A method for the preparation of a lithium electrode with a solid-state electrolyte interface layer of a rich inorganic hybrid constructed by a one-step liquid siloxane plasma, characterized in that, The preparation method described above uses lithium sheet as substrate and methyl liquid siloxane as plasma source to construct a hybrid solid electrolyte interface layer in one step via plasma method to obtain a composite lithium electrode. The methyl liquid siloxane includes at least one of octamethyltrisiloxane, polydimethylsiloxane, methylvinylcyclosiloxane, and decamethylcyclopentasiloxane. The reaction conditions are: radio frequency power of 100-140W, vacuum degree of 2-25Pa, and reaction time of 30-90s. The formed inorganic-rich hybrid artificial solid electrolyte interface layer (SEI) includes lithium silicate and lithium carbonate.

2. The method of claim 1, wherein the method is characterized by: Includes the following steps: (1) Methyl liquid siloxane is sealed and loaded into the liquid source device, and lithium sheet is sealed in the plasma device; (2) Connect the plasma device and liquid source device to the plasma generator, then evacuate the plasma device and introduce methyl liquid siloxane vapor; (3) Adjust the radio frequency power, and after a certain reaction time after ignition, a composite lithium electrode with an interface layer rich in inorganic hybrid solid electrolyte is formed.

3. The method for preparing a lithium electrode with an inorganic hybrid solid electrolyte interface layer constructed in a one-step liquid siloxane plasma method according to claim 2, characterized in that, In step (1), the methyl liquid siloxane is octamethyltrisiloxane.

4. The method for preparing a lithium electrode with an inorganic hybrid solid electrolyte interface layer constructed in a one-step liquid siloxane plasma method according to claim 2, characterized in that, In step (2), the vacuum is evacuated to a vacuum level of 1-10 Pa, and after octamethyltrisiloxane vapor is introduced, the vacuum level is 2-25 Pa.

5. The method for preparing a lithium electrode with an inorganic hybrid solid electrolyte interface layer constructed in a one-step liquid siloxane plasma method according to claim 4, characterized in that, The radio frequency power is 110-125W, and the vacuum degree is 10-20Pa.

6. The method for preparing a lithium electrode with an inorganic hybrid solid electrolyte interface layer constructed in a one-step liquid siloxane plasma method according to claim 2, characterized in that, The thickness of the inorganic hybrid solid electrolyte interface layer is 5-10 μm.

7. A lithium electrode prepared by the method according to any one of claims 1-6 using a one-step plasma method to construct an inorganic hybrid solid electrolyte interface layer.

8. The application of a lithium electrode with an inorganic hybrid solid electrolyte interface layer constructed by a one-step liquid siloxane plasma method as described in claim 7 in the field of batteries.

Images