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Surface-stabilized and prelithiated anode active materials for lithium batteries and production method

a lithium battery and active material technology, applied in the field of surface stabilization and prelithiation of anode active materials for lithium batteries, can solve the problems of loss of particle-to-particle contact between active materials, affecting the life of charge-discharge cycles, and affecting the specific capacity of batteries. , to achieve the effect of prolonging the charge-discharge cycle and improving the specific capacity

Active Publication Date: 2019-03-21
GLOBAL GRAPHENE GRP INC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The present invention provides a new material for the anode of a lithium battery that improves its capacity and lifespan. The material is prelithiated in a separate reactor and then deposited onto a surface-stabilizing layer using another reactor. This two-step process reduces equipment costs and saves time. The first step involves electrochemical prelithiation in a reactor, which may be the same as the second step. Overall, this patent describes a more efficient and effective method of making anode materials for lithium batteries.

Problems solved by technology

On repeated charge and discharge operations, the alloy particles tend to undergo pulverization and the current collector-supported thin films are prone to fragmentation due to expansion and contraction of the anode active material during the insertion and extraction of lithium ions.
This pulverization or fragmentation results in loss of particle-to-particle contacts between the active material and the conductive additive or contacts between the anode material and its current collector.
These adverse effects result in a significantly shortened charge-discharge cycle life.
In fact, most of prior art composite electrodes have deficiencies in some ways, e.g., in most cases, less than satisfactory reversible capacity, poor cycling stability, high irreversible capacity, ineffectiveness in reducing the internal stress or strain during the lithium ion insertion and extraction cycles, and some undesirable side effects.
These prior art materials do not offer a high lithium insertion capacity and this capacity also tends to decay rapidly upon repeated charging and discharging.
However, the notion that this amount of lithium that determines the battery capacity is totally supplied from the cathode, limits the choice of cathode active materials because the active materials must contain removable lithium.
In particular, these delithiated products tend to react with the electrolyte and generate heat, which raises safety concerns.
These changes in potential may give rise to parasitic reactions on both electrodes, but more severely on the anode.
However, as the SEI layer is formed, a portion of the lithium introduced into the cells via the cathode is irreversibly bound and thus removed from cyclic operation, i.e. from the capacity available to the user.
A further drawback is that the formation of the SEI layer on the anode after the first charging operation may be incomplete and will continue to progress during the subsequent charging and discharge cycles.
Even though this process becomes less pronounced with an increasing number of repeated charging and discharge cycles, it still causes continuous abstraction, from the system, of lithium which is no longer available for cyclic operation and thus for the capacity of the cell.
Additionally, as indicated earlier, the formation of a solid-electrolyte interface layer consumes about 10% to 30% of the amount of lithium originally stored at the cathode, which is already low in capacity (typically <200 mAh / g).
However, prelithiated carbon- or graphite-based anode active materials lead to electrodes which can be handled only under non-oxidizing and dry conditions, making practical production of lithium ion batteries difficult.
Such an additional electrode makes the battery very complicated and difficult to make.
Switching between two orientations is not a good strategy since it would complicate the handling of the battery and an average consumer would not pay attention to such a detail to ensure proper operation of such a battery.
Again, this additional electrode further complicates the manufacture and operation of a resulting battery.
The resulting multi-component, multi-phase mixture is still sensitive to the presence of oxygen and water contents in the air, thus significantly complicating the battery manufacturing operations.(4) In a follow-on patent application, Gao, et al.
Both the discrete lithium metal particles and lithiated carbonaceous material (graphite) are unstable in an oxygen- or moisture-containing environment.
Furthermore, Gao, et al. have not fairly suggested how other anode active materials than graphite can be prelithiated in a controlled manner (e.g., without inducing a lithium coating on the surface of active material particles).

Method used

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  • Surface-stabilized and prelithiated anode active materials for lithium batteries and production method

Examples

Experimental program
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Effect test

example 2

tabilized Prelithiated Tin Oxide Particles

[0122]Tin oxide (SnO2) nano particles were obtained by the controlled hydrolysis of SnCl4.5H2O with NaOH using the following procedure: SnCl4.5H2O (0.95 g, 2.7 m-mol) and NaOH (0.212 g, 5.3 m-mol) were dissolved in 50 mL of distilled water each. The NaOH solution was added drop-wise under vigorous stirring to the tin chloride solution at a rate of 1 mL / min. This solution was homogenized by sonication for 5 m in. Subsequently, the resulting hydrosol was reacted with H2SO4. To this mixed solution, few drops of 0.1 M of H2SO4 were added to flocculate the product. The precipitated solid was collected by centrifugation, washed with water and ethanol, and dried in vacuum. The dried product was heat-treated at 400° C. for 2 h under Ar atmosphere.

[0123]Samples of various different tin oxide particles were subjected to electrochemical prelithiation and / or electrochemical formation of lithium-containing species bonded to particle surfaces using lithiu...

example 3

tabilized Prelithiated Tin (Sn) Nano Particles

[0125]Nano particles (76 nm in diameter) of Sn were encapsulated with a thin layer of phenolic resin shell via the spray-drying method, followed by a heat treatment from 350-600° C. for 4 hours to obtain carbon-coated Sn nano particles. Half of these C-coated Sn particles were subjected to encapsulation by a mixture of Li4B, Na4B, LiF, and NaF, which were obtained by electrochemical decomposition of an electrolyte containing lithium boron-fluoride (LiBF4) and NaBF4 dissolved in DEC. Un-protected Sn nano particles from the same batch were also investigated to determine and compare the cycling behaviors of the lithium-ion batteries containing these particles as the anode active material.

[0126]Shown in FIG. 5 are the specific capacities of 3 lithium batteries: one having an anode active material featuring surface-stabilized carbon-encapsulated Sn particles, one having carbon-encapsulated Sn particles, and one having un-protected Sn particle...

example 4

tabilized Prelithiated Si Nanowire-Based Anode Materials

[0127]In a typical procedure of Si nanowire production, approximately 2.112 g of silicon powders (average diameter 2.64 μm) were mixed with 80 ml of a 0.1M aqueous solution of Ni(NO3).6H2O and vigorously stirred for 30 min. Then, water was evaporated in a rotary evaporator and the solid remnants were completely dried in an oven at 150° C. The final sample (Ni-impregnated Si powers) was obtained by grinding the solids in a mortar.

[0128]Subsequently, 0.03 g of Ni-impregnated Si particles was placed in a quartz boat, and the boat was placed in a tube furnace. The sample was reduced at 500° C. for 4 hours under flowing Ar (180 sccm) and H2 (20 sccm), then the temperature was raised to 990° C. to catalytically synthesize Si nanowires; Si nanowires were found to emanate from original micron-scaled Si particles. For the purpose of separating Si nanowires, for instance, every 0.1 g of the reacted Si powders was mixed with 10 ml of etha...

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Abstract

A prelithiated and surface-stabilized anode active material for use in a lithium battery, comprising a protected anode active material particle comprising a surface-stabilizing layer embracing a core particle, wherein the surface-stabilizing layer comprises a lithium- or sodium-containing species chemically bonded to the core particle and the lithium- or sodium-containing species is selected from Li2CO3, Li2O, Li2C2O4, LiOH, LiX, ROCO2Li, HCOLi, ROLi, (ROCO2Li)2, (CH2OCO2Li)2, Li2S, LixSOy, Li4B, Na4B, Na2CO3, Na2O, Na2C2O4, NaOH, NaiX, ROCO2Na, HCONa, RONa, (ROCO2Na)2, (CH2OCO2Na)2, Na2S, NaxSOy, or a combination thereof, wherein X=F, Cl, I, or Br, R=a hydrocarbon group, 0<x≤1, and 1≤y≤4; wherein the lithium- or sodium-containing species is preferably derived from an electrochemical decomposition reaction and the core particle is prelithiated to contain an amount of lithium from 1% to 100% of the maximum lithium content that can be included in the core particle of anode active material.

Description

FIELD OF THE INVENTION[0001]The present invention provides a method of producing an anode active material and anode electrode for a secondary battery, particularly a rechargeable lithium-ion or lithium metal battery that comprises an anode containing a surface-stabilized prelithiated anode active material.BACKGROUND[0002]Concerns over the safety of earlier lithium secondary batteries led to the development of lithium ion secondary batteries, in which pure lithium metal sheet or film was replaced by carbonaceous materials as the negative electrode (anode). The carbonaceous material may comprise primarily graphite that is intercalated with lithium and the resulting graphite intercalation compound may be expressed as LixC6, where x is typically less than 1. In order to minimize the loss in energy density due to this replacement, x in LixC6 must be maximized and the irreversible capacity loss Qir in the first charge of the battery must be minimized. The maximum amount of lithium that ca...

Claims

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Application Information

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IPC IPC(8): H01M4/134H01M4/136H01M4/137H01M4/62H01M4/1315H01M4/133H01M4/13915H01M4/1393H01M4/1395H01M4/1397H01M4/1399
CPCH01M4/366H01M4/134H01M4/136H01M4/137H01M4/621H01M4/1315H01M4/133H01M4/13915H01M4/1393H01M4/1395H01M4/1397H01M4/1399H01M10/052H01M4/0461H01M4/38H01M4/62H01M10/0525Y02E60/10
Inventor ZHAMU, ARUNAJANG, BOR Z.
Owner GLOBAL GRAPHENE GRP INC
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