All-solid-state battery and preparation method therefor

1. An all-solid-state battery, comprising a positive electrode, a negative electrode, and a solid-state electrolyte located between the positive electrode and the negative electrode, wherein the negative electrode comprises a first negative electrode and a second negative electrode, the second negative electrode is located on a side of the first negative electrode, the solid-state electrolyte comprises a first solid-state electrolyte and a second solid-state electrolyte, the first solid-state electrolyte is located between the positive electrode and the first negative electrode, the second solid-state electrolyte is located between the positive electrode and the second negative electrode, and a roughness of the second solid-state electrolyte is greater than a roughness of the first solid-state electrolyte;

wherein the roughness of the first solid-state electrolyte and the roughness of the second solid-state electrolyte are both greater than a surface roughness of the negative electrode, and a difference between the roughness of the second solid-state electrolyte and a roughness of the second negative electrode is greater than a difference between the roughness of the first solid-state electrolyte and a roughness of the first negative electrode; and

wherein the difference between the roughness of the second solid-state electrolyte and the roughness of the second negative electrode is 100% to 500% greater than the difference between the roughness of the first solid-state electrolyte and the roughness of the first negative electrode.

2. The all-solid-state battery according to claim 1 , wherein a cross-sectional area of the first negative electrode is larger than a cross-sectional area of the second negative electrode.

3. The all-solid-state battery according to claim 1 , wherein the positive and negative electrodes further comprise current collectors, wherein materials of the current collectors independently comprise any one or a combination of at least two of aluminum, copper, nickel or zinc.

4. The all-solid-state battery according to claim 1 , wherein a positive electrode active material layer of the positive electrode comprises a positive electrode active material;

optionally, the positive electrode active material comprises any one or a combination of at least two of LiCoO 2 , LiMnO 2 , LiNiO 2 , LiVO 2 , LiNi 1/3 CO 1/3 Mn 1/3 O 2 , LiMn 2 O 4 , LiTi 5 O 12 , Li(Ni 0.5 Mn 1.5 )O 4 , LiFePO 4 , LiMnPO 4 , LiNiPO 4 , LiCoPO 4 or LiNbO 3 ;

optionally, the positive electrode active material layer further comprises any one or a combination of at least two of a solid-state electrolyte material, a conductive material or an adhesive material;

optionally, the solid-state electrolyte material comprises a sulfide solid-state electrolyte material and/or an oxide solid-state electrolyte material;

optionally, the conductive material comprises any one or a combination of at least two of acetylene black, conductive carbon black, ketjen black or carbon fiber;

optionally, the adhesive material comprises any one or a combination of at least two of polyvinylidene fluoride, carboxymethylcellulose sodium or styrene-butadiene rubber;

optionally, a thickness of the positive electrode active material layer is 1 μm to 500 μm, optionally 50 μm to 200 μm;

optionally, a surface of the positive electrode active material layer is coated with a coating;

optionally, a material of the coating comprises any one or a combination of at least two of LiNbO 3 , Li 3 PO 4 or LiPON;

optionally, a thickness of the coating is 1 nm to 20 nm.

5. The all-solid-state battery according to claim 1 , wherein a negative electrode active material layer of the negative electrode comprises a negative electrode active material;

optionally, the negative electrode active material comprises any one or a combination of at least two of a metallic active material, a carbon active material or an oxide active material;

optionally, the metallic active material comprises any one or a combination of at least two of Si, Sn, In, Si—Al alloy or Si—In alloy;

optionally, the carbon active material comprises any one or a combination of at least two of graphite, hard carbon or soft carbon;

optionally, the oxide active material comprises Li 4 Ti 5 O 12 ;

optionally, the negative electrode active material layer further comprises any one or a combination of at least two of a solid-state electrolyte material, a conductive material or an adhesive material;

optionally, the solid-state electrolyte material comprises a sulfide solid-state electrolyte material and/or an oxide solid-state electrolyte material;

optionally, the conductive material comprises any one or a combination of at least two of acetylene black, conductive carbon black, ketjen black or carbon fiber;

optionally, the adhesive material comprises any one or a combination of at least two of polyvinylidene fluoride, carboxymethylcellulose sodium or styrene-butadiene rubber;

optionally, a thickness of the negative electrode active material layer is 1 μm to 500 μm, optionally 50 μm to 200 μm;

optionally, the first negative electrode and the second negative electrode share a same current collector.

6. The all-solid-state battery according to claim 1 , wherein a material of the solid-state electrolyte located between the positive electrode and the negative electrode comprises any one or a combination of at least two of a sulfide solid-state electrolyte material, an oxide solid-state electrolyte material or a polymer solid-state electrolyte material;

optionally, the thickness of the first solid-state electrolyte between the positive electrode and the negative electrode is 10 μm to 300 μm;

optionally, the thickness of the first solid-state electrolyte between the positive electrode and the optionally, the thickness of the first solid-state electrolyte between the positive electrode and the negative electrode is 20 μm to 60 μm.

7. The all-solid-state battery according to claim 1 , wherein a numerical range of the roughness of the first solid-state electrolyte is 0.1 μm to 30 μm.

8. The all-solid-state battery according to claim 1 , wherein a numerical range of the roughness of the second solid-state electrolyte is 0.1 μm to 50 μm.

9. The all-solid-state battery according to claim 1 , wherein the first negative electrode is connected with the second negative electrodes.

10. The all-solid-state battery according to claim 1 , wherein the second negative electrodes are located on both sides of the first negative electrode.

11. The all-solid-state battery according to claim 1 , wherein a thickness of the first solid-state electrolyte is less than a thickness of each of second solid-state electrolytes.

12. The all-solid-state battery according to claim 1 , wherein a thickness of the first negative electrode is greater than a thickness of each of the second negative electrodes.

13. The all-solid-state battery according to claim 1 , wherein the difference between the roughness of the second solid-state electrolyte and the roughness of the second negative electrode is 200% to 300% greater than the difference between the roughness of the first solid-state electrolyte and the roughness of the first negative electrode;

optionally, the roughness of the second solid-state electrolyte is 30% to 150% greater than the roughness of the first solid-state electrolyte;

optionally, the roughness of the second negative electrode is greater than the roughness of the first negative electrode.