TECHNICAL FIELD

The present disclosure generally relates to electrodes for batteries.

BACKGROND ART

Lithium-sulfur (Li—S) batteries show great promise as the next-generation high-energy-density batteries, because of their low mass densities (Li: 0.534 g cm−3; S: 2.07 g cm−3) and high theoretical capacities (Li: 3860 mAh kg−1; S: 1675 mAh kg−1). Stable Li—S batteries require high coulombic efficiency (CE) and high cycling stability of both anode and cathode.

However, dendrite formation on the Li metal anode and shuttle effects of soluble polysulfides on the cathode lead to low CE and rapid capacity decay of Li—S batteries. Li metal anodes face the issues of uncontrolled dendrite growth, large volume change, and unstable solid electrolyte interphase (SEI) in charge-discharge processes. Several strategies have been proposed to achieve stable Li metal anodes, including artificial SEI design, electrolyte additives, and high-surface-area Li hosts. The former two approaches may stabilize the surface of Li metal by physically or chemically inhibiting the dendrite formation. The latter is to reduce Li−flux and lower the localized current density with high-surface-area structures, which can improve the stability of SEI. Nevertheless, it is still difficult to realize high areal capacity and long cycle life of Li anodes with limited amount of Li source. On the cathode side, in order to resolve the shuttle effects of polysulfides, physical confinement approaches aiming to trap sulfur within porous hosts have been pursued, but the results in terms of capacity decay and kinetic sluggishness is still limited. Instead, metal oxides, sulfides, and even nitrides have been explored to accelerate reduction of the polysulfides (Li2Sx, 3≤x≤8) and strengthen attachment of the sulfide (i.e., Li2S, Li2S2). Nevertheless, the relatively low conductivity and insufficient catalytic effects adversely affect long-term cyclability of sulfur cathodes.

Apart from improving the coulombic efficiency and capacity, it is of paramount importance to fabricate Li—S electrodes with sufficient flexibility for flexible and wearable purposes. Up till now, only a limited number of flexible sulfur cathodes made with graphene and carbon nanotubes have been reported. However, there is no report on Li metal anodes with good flexibility. For example, sulfur cathodes are typically paired with thick Li metal foils or wires to test the electrochemical properties. Such an assembly does not have good flexibility, because of the low fatigue resistance of pure Li metal. As such, there is still no report to date for achieving flexible Li—S full cells with high energy density and stable cycling.

A need therefore exists for a lithium electrode and a sulfur electrode to eliminate or at least diminish the disadvantages and problems described above.

SUMMARY OF THE INVENTION

Provided herein is electrode for a battery. The electrode comprises lithium metal and a fabric comprising one or more fibers. Each of the one or more fibers being at least partially covered by a metal layer, and the lithium metal is attached on the metal layer.

In certain embodiments, the metal layer comprises copper, nickel, silver, zinc or gold.

In certain embodiments, the metal layer has a thickness in a range of 50 nm to 300 nm.

In certain embodiments, a portion of the lithium metal is in a form of a sheet or a flake.

In certain embodiments, the sheet has a lateral dimension in a range of 50 nm to 200 nm and a thickness in a range of 1-100 nm and the flake has a lateral dimension in a range of 1 μm to 5 μm and a thickness in a range of 1-100 nm.

In certain embodiments, the lithium metal is further present in pores in the fabric.

In certain embodiments, each of the one or more fibers comprises a diameter in a range of 5 μm to 20 μm.

In certain embodiments, the metal layer comprises copper; the metal layer has a thickness in a range of 50 nm to 300 nm; a portion of the lithium metal is in a form of a sheet or a flake; and the sheet has a lateral dimension in a range of 50 nm to 200 nm and a thickness in a range of 1-100 nm and the flake has a lateral dimension in a range of 1 μm to 5 μm and a thickness in a range of 1-100 nm.

Provided herein is an electrode for a battery. The electrode comprises a sulfur composite comprising a conductive binder and sulfur and a fabric comprising one or more fibers. Each of the one or more fibers being at least partially covered by a nickel layer, and the sulfur composite is attached on the nickel layer.

In certain embodiments, the nickel layer has a thickness in a range of 50 nm to 300 nm.

In certain embodiments, the conductive binder is a nitrogen and sulfur co-doped graphene.

In certain embodiments, the nitrogen and sulfur co-doped graphene has a molar ratio of nitrogen to sulfur in a range of 0.8:1.2 to 1.2:0.8.

In certain embodiments, the sulfur composite further comprises a conductive additive.

In certain embodiments, the conductive additive is carbon black.

In certain embodiments, the sulfur composite is further present in pores in the fabric.

In certain embodiments, the electrode further comprises an interfacial polymer layer sandwiched between the each of the one or more fibers and the nickel layer.

In certain embodiments, the nickel layer has a thickness in a range of 50 nm to 300 nm; the conductive binder is a nitrogen and sulfur co-doped graphene; and the sulfur composite further comprises carbon black.

Provided herein is a lithium metal sulfur battery. The lithium metal sulfur battery comprises an anode and a cathode. The anode comprises lithium metal and a first fabric comprising one or more first fibers. Each of the one or more first fibers being at least partially covered by a metal layer, and the lithium metal is attached on the metal layer. The cathode comprises a sulfur composite comprising a conductive binder and sulfur and a second fabric comprising one or more second fibers. Each of the one or more second fibers being at least partially covered by a nickel layer, and the sulfur composite is attached on the nickel layer.

In certain embodiments, the metal layer comprises copper, the conductive binder is a nitrogen and sulfur co-doped graphene; and the sulfur composite further comprises carbon black.

Provided herein is electrode for a battery. The electrode comprises a sulfur composite comprising a conductive binder and sulfur and one or more fibers. Each of the one or more fibers being at least partially covered by a nickel layer, and the sulfur composite is attached on the nickel layer.

These and other aspects, features and advantages of the present disclosure will become more fully apparent from the following brief description of the drawings, the drawings, the detailed description of certain embodiments and appended claims.

