Solid-state battery and positive electrode material thereof

Abstract

The invention discloses a solid-state battery and a positive electrode material thereof. The solid-state battery consists of a lithium storage positive electrode, a battery electrolyte and a lithium-rich negative electrode. Wherein the lithium-storing positive electrode comprises an embedded lithium-storing transition metal chalcogenide and a composite material of the embedded lithium-storing transition metal chalcogenide. The positive electrode material has ionic conductivity and electronic conductivity at the same time, a three-dimensional ionic and electronic conductive network structure is formed in the positive electrode, and the network structure is beneficial to intercalation and deintercalation of lithium ions. The crystal structure of the transition metal chalcogenide can be a layered structure or a SiFerel phase, and transition metal contained in the transition metal chalcogenide can be at least one of IVB, VB, VIB and VIIB group metal elements. In the lithium ion intercalation and deintercalation process, the transition metal is subjected to valence change reaction. By introducing the positive electrode material, the weight ratio of inactive substances in the battery is effectively reduced, and the energy density of the solid electrolyte is further improved.

Description

Technical Field

[0001] This invention relates to the field of lithium batteries, and more particularly to a solid-state battery and its cathode material. Background Technology

[0002] The development of energy storage technology is crucial for multiple fields such as military, transportation, and portable electronics. Its development direction includes improving energy density, ensuring safety performance, and enhancing transport stability. Lithium-sulfur batteries are based on the reversible reaction of metallic lithium and elemental sulfur, and their theoretical specific capacity is as high as 1675 mAh / g, making them one of the types of energy storage devices with the highest energy density currently available.

[0003] However, for solid-state lithium-sulfur batteries, the low electronic and ionic conductivity of elemental sulfur, coupled with the poor wettability of the solid electrolyte to the cathode material, limits the transport of sulfur ions within the cathode material, thus affecting the battery capacity. To improve the conductivity of the cathode material, researchers typically reduce the particle size of elemental sulfur, increasing its dispersion within the cathode material, and add a large amount of electrolyte and conductive carbon to the cathode. However, this significantly reduces the sulfur loading in the cathode material, thereby affecting the actual battery capacity.

[0004] To fully leverage the capacity advantage of lithium-sulfur batteries, developing a cathode material with high conductivity and high sulfur loading is crucial for the commercial application of all-solid-state lithium-sulfur batteries. This invention addresses this need by developing a class of transition metal sulfides with both ionic and electronic conductivity as cathode materials combined with high-capacity sulfur. These sulfides not only participate in the lithium-sulfur reaction as electrode materials but also act as a solid electrolyte, providing ion transport channels. This significantly reduces the amount of electrolyte and conductive additives used in the cathode material, providing more space for sulfur loading. Under extreme conditions, transition metal sulfides can even completely replace solid electrolyte conductive additives, achieving zero solid electrolyte content in the cathode, thereby significantly improving the volumetric and gravimetric energy density of the cathode material. Summary of the Invention

[0005] To address the problems of existing technologies, this invention proposes a solid-state battery comprising an embedded lithium storage positive electrode, a battery electrolyte, and a lithium-rich negative electrode. The embedded lithium storage positive electrode comprises a positive electrode material of transition metal chalcogenides and their composite materials. These materials possess both ionic and electronic conductivity and form a three-dimensional ionic and electronic conductive network structure within the positive electrode for lithium ion insertion and extraction. The crystal structure of these transition metal chalcogenides can be a layered structure or a Chevrell phase, wherein the transition metal includes at least one of group IVB, VB, VIB, and VIIB metal elements. During the lithium ion insertion and extraction process, the transition metal undergoes a valence change reaction.

[0006] Preferably, the transition metal chalcogenide is MxSy, where M is a cation, including one or more of Mo, Ti, V, Cr, Mn, Nb, Zr, W, Re, and Ta; 1≤x≤9, 1≤y≤9, and the values ​​of x and y must maintain the electroneutrality of the compound.

[0007] Preferably, the cathode material further includes one or more cathode materials selected from S, Li2S8, Li2S4, Li2S2, Li2S, LiFePO4, LiMn2O4, LiCoO2, LiNi0.5Mn1.5O4, LiNi0.5Mn0.5O2, LiNiO2, LiNi1 / 3Co1 / 3Mn1 / 3O2, LiNi0.5Co0.3Mn0.2O2, LiNi0.6Co0.2Mn0.2O2, LiNi0.8Co0.1Mn0.1O2, LiNiCoAlO2, and Li4Ti5O12, which are mixed with transition metal chalcogenides and their composite materials for embedded lithium storage.

[0008] Preferably, the positive electrode further includes a solid electrolyte comprising 0-30% of the positive electrode mass and a carbon material comprising 0-30% of the positive electrode mass.

[0009] Preferably, the mass percentage of transition metal chalcogenides in the composite material is 5% to 100%.

[0010] Preferably, the carbon material includes one or more of Super-P carbon black, carbon fiber, carbon nanotubes, graphene, and acetylene black.

[0011] Preferably, the battery electrolyte is a solid electrolyte disposed between the positive and negative electrodes, and contains lithium superion conductor material.

[0012] Preferably, the lithium-rich anode is a lithium metal, lithium alloy, lithium carbon, or silicon-based material with pre-intercalated lithium, containing a current collector.

[0013] On the other hand, the present invention provides a cathode material for the aforementioned solid-state battery, comprising a transition metal chalcogenide compound for embedded lithium storage and its composite material; these materials simultaneously possess ionic and electronic conductivity, and form a three-dimensional ionic and electronic conductive network structure within the cathode for lithium ion insertion and extraction. The crystal structure of the transition metal chalcogenide compound can be a layered structure or a Chevrell phase, wherein the transition metal includes at least one of group IVB, VB, VIB, and VIIB metal elements; during the lithium ion insertion and extraction process, the transition metal undergoes a valence change reaction.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] This invention provides a novel cathode material for solid-state batteries, comprising a class of electrochemically active transition metal chalcogenides. These compounds not only participate in electrochemical reactions as active materials but also possess excellent electronic and particle conductivity. This allows them to reduce or even eliminate the need for adding solid electrolytes and conductive additives to the cathode material. Therefore, they can completely or partially replace solid electrolytes and conductive additives in the electrode, thereby increasing the content of electrochemically active materials in the electrode and thus improving the battery's energy density. The novel solid-state battery based on this composite cathode therefore exhibits high energy density and good safety characteristics. Detailed Implementation

[0016] Example 1

[0017] This embodiment presents a high-capacity solid-state battery comprising a positive electrode, a negative electrode, and a solid electrolyte. The positive electrode uses Mo6S8 material, while the negative electrode is composed of lithium sheets. The solid electrolyte used in the battery comprises two layers: one layer is Li10GeP2S12, facing the positive electrode material; the other layer is a mixture of 75% Li2S-25% P2S5, facing the metallic lithium. The charge-discharge curve of the novel solid-state battery in Embodiment 1 of this invention is shown after 20 cycles. After 20 weeks of cycling testing, the battery's discharge specific capacity reaches 97 mAh / g.

Claims

1. A solid-state battery, characterized in that, The battery comprises an embedded lithium storage cathode, a battery electrolyte, and a lithium-rich anode. The embedded lithium storage cathode includes cathode materials made of transition metal chalcogenides and their composites. These materials possess both ionic and electronic conductivity and form a three-dimensional ionic and electronic conductive network structure within the cathode for lithium ion insertion and extraction. The crystal structure of these transition metal chalcogenides can be a layered structure or a Chevrell phase, and the transition metals include at least one of group IVB, VB, VIB, and VIIB metals. During the lithium ion insertion and extraction process, the transition metals undergo valence change reactions.

2. The solid-state battery according to claim 1, characterized in that, The transition metal chalcogenide is specifically MxSy, where M is a cation, including one or more of Mo, Ti, V, Cr, Mn, Nb, Zr, W, Re, and Ta; 1≤x≤9, 1≤y≤9, and the values ​​of x and y must maintain the electroneutrality of the compound.

3. The solid-state battery according to claim 1, characterized in that, The cathode material also includes one or more of the following cathode materials mixed with transition metal chalcogenides and their composites for embedded lithium storage: S, Li2S8, Li2S4, Li2S2, Li2S, LiFePO4, LiMn2O4, LiCoO2, LiNi0.5Mn1.5O4, LiNi0.5Mn0.5O2, LiNiO2, LiNi1 / 3Co1 / 3Mn1 / 3O2, LiNi0.5Co0.3Mn0.2O2, LiNi0.6Co0.2Mn0.2O2, LiNi0.8Co0.1Mn0.1O2, LiNiCoAlO2, and Li4Ti5O12.

4. The solid-state battery according to claim 1, characterized in that, The positive electrode also includes a solid electrolyte comprising 0-30% of the positive electrode mass and carbon materials comprising 0-30% of the positive electrode mass.

5. The solid-state battery according to claim 1, characterized in that, In composite materials, the mass percentage of transition metal chalcogenides ranges from 5% to 100%.

6. The solid-state battery according to claim 1, characterized in that, Carbon materials include one or more of the following: Super-P carbon black, carbon fiber, carbon nanotubes, graphene, and acetylene black.

7. The solid-state battery according to claim 1, characterized in that, The battery electrolyte is a solid electrolyte located between the positive and negative electrodes and contains lithium superion conductor material.

8. The solid-state battery according to claim 1, characterized in that, Specifically, lithium-rich anodes are metallic lithium, lithium alloys, lithium carbon, or silicon-based materials with pre-intercalated lithium, which contain current collectors.

9. A positive electrode material in a solid-state battery according to claim 1, characterized in that, This includes transition metal chalcogenides and their composites for embedded lithium storage; these materials possess both ionic and electronic conductivity, forming a three-dimensional ionic and electronic conductive network structure within the positive electrode for lithium-ion insertion and extraction. The crystal structure of the transition metal chalcogenides can be a layered structure or a Chevrell phase, wherein the transition metal includes at least one element from Groups IVB, VB, VIB, and VIIB; during lithium-ion insertion and extraction, the transition metal undergoes a valence change reaction.