Search

EP-3483957-B1 - COMPOSITIONS FOR FORMING A POROUS INSULATING LAYER, ELECTRODE FOR NON-AQUEOUS ELECTROLYTE RECHARGEABLE BATTERY, THE RECHARGEABLE BATTERY AND METHOD FOR MANUFACTURING THE ELECTRODE

EP3483957B1EP 3483957 B1EP3483957 B1EP 3483957B1EP-3483957-B1

Inventors

  • FUKATANI, TOMOYUKI
  • HOSHIBA, KOJI

Dates

Publication Date
20260506
Application Date
20181031

Claims (12)

  1. An electrode (30) for a non-aqueous electrolyte rechargeable battery (10), the electrode comprising a current collector (31), an active material layer (32) disposed on a main surface of the current collector (31), and a porous insulating layer (33) formed on the active material layer (32) by utilizing a composition for forming the porous insulating layer, wherein the active material layer (32) comprises an active material capable of electrochemically intercalating and deintercalating lithium ions and an active material layer binder, wherein the composition for forming the porous insulating layer (33) comprises a solvent including an organic solvent and an insulating inorganic particle, and wherein a distance between Hansen solubility parameters of the active material layer binder and the organic solvent represented by Equation 2 is greater than or equal to 8.0 (MPa) 1/2 : HSP distance = 4 × δ D binder − δ D solvent 2 + δ P binder − δ P solvent 2 + δ H binder − δ H solvent 2 1 / 2 In Equation 2, δ D(binder) denotes dispersion force of the active material layer binder, δ D(solvent) denotes dispersion force of the organic solvent, δ P(binder) denotes polarity force of the active material layer binder, δ P(solvent) denotes polarity force of the organic solvent, δ H(binder) denotes a hydrogen bond force of the active material layer binder, and δ H(solvent) denotes a hydrogen bond force of the organic solvent, and HSP distance is measured at a standard temperature 25 °C.
  2. The electrode of claim 1, wherein a distance between Hansen solubility parameters of the active material and the organic solvent is greater than or equal to 5.0 (MPa) 1/2 .
  3. The electrode of claim 1, wherein a distance between the Hansen solubility parameters of the active material and the organic solvent is greater than or equal to 8.0 (MPa) 1/2 .
  4. The electrode of claim 1, wherein the organic solvent has a distance (Ra) of the Hansen solubility parameter represented by Equation 1 of greater than or equal to 5.0 (MPa) 1/2 : Ra = 4 × 18.0 − δ D solvent 2 + 9.3 − δ P solvent 2 + 7.7 − δ H solvent 2 1 / 2 wherein, in Equation 1, δ D (solvent) denotes dispersion force of the organic solvent in (MPa) 1/2 , δ P(solvent) denotes polarity force of the organic solvent in (MPa) 1/2 , and δ H(solvent) denotes a hydrogen bond force of the organic solvent in (MPa) 1/2 .
  5. The electrode of claim 1, wherein the composition for forming the porous insulating layer (33) further comprises a porous insulating layer binder.
  6. The electrode of claim 1, wherein the solvent comprises water.
  7. The electrode of claim 1, wherein a boiling point of the organic solvent at 1 atm is greater than or equal to 160 °C.
  8. The electrode of claim 1, wherein the organic solvent comprises an alcohol-based compound.
  9. The electrode of claim 1, wherein the organic solvent comprises a glycolalkyl ether-based compound.
  10. The electrode of claim 1, wherein the composition for forming the porous insulating layer (33) further comprises a polyolefin-based polymer particle.
  11. A non-aqueous electrolyte rechargeable battery (10) comprising the electrode (30) for a non-aqueous electrolyte rechargeable battery of claim 1.
  12. A method for manufacturing an electrode for a non-aqueous electrolyte rechargeable battery (10), the method comprising forming a porous insulating layer (33) on an active material layer (32) disposed on a main surface of a current collector (31), by using a composition for forming a porous insulating layer, wherein the active material layer (32) comprises at least an active material capable of electrochemically intercalating and deintercalating lithium ions and an active material layer binder, the composition for forming the porous insulating layer comprises at least a solvent and an insulating inorganic particle, the solvent comprising an organic solvent, and a distance between Hansen solubility parameters of the active material layer binder and the organic solvent represented by Equation 2 is greater than or equal to 8.0 (MPa) 1/2 : HSP distance = 4 × δ D binder − δ D solvent 2 + δ P binder − δ P solvent 2 + δ H binder − δ H solvent 2 1 / 2 In Equation 2, δ D(binder) denotes dispersion force of the active material layer binder, δ D(solvent) denotes dispersion force of the organic solvent, δ P(binder) denotes polarity force of the active material layer binder, δ P(solvent) denotes polarity force of the organic solvent, δ H(binder) denotes a hydrogen bond force of the active material layer binder, and δ H(solvent) denotes a hydrogen bond force of the organic solvent, and HSP distance is measured at a standard temperature 25°C.

Description

BACKGROUND OF THE INVENTION (a) Field of the Invention The present disclosure relates to an electrode for a non-aqueous electrolyte rechargeable battery, and a method for manufacturing the non-aqueous electrolyte rechargeable battery and the electrode for a non-aqueous electrolyte rechargeable battery. (b) Description of the Related Art A non-aqueous electrolyte rechargeable battery is required to have relatively high energy density and simultaneously, secure safety. In response to this request, a shutdown function of increasing internal resistance of the battery by closing pores of a separator through melting during abnormal overheating due to an internal short circuit of the battery and the like is, for example, being used. In addition, a method of preventing the internal short circuit by directly forming a porous insulating layer on the surface of an electrode aside from the shutdown function by the separator has been suggested (e.g., Japanese Patent Laid-Open Publication No. 2008-226566). The electrode including this heat-resistance insulating layer may be for example manufactured as follows. First, an active material-containing paste as aqueous slurry is coated on a current collector and then, dried and compressed to form an active material layer. On the active material layer, material slurry for a porous insulating layer is coated and dried to form the porous insulating layer. A further example may be found in US 2014/186682 A1, which discloses an electrode of a lithium-ion battery including a porous insulating layer made by coating a composition on an active material layer. CN 106 898 721 A discloses a composition for forming a porous insulating layer including an inorganic particle (alumina), polyvinylidene difluoride (Kynar) particles (corresponding to polyolefin particle), water and ethanol. Another example may be found in US 2017/033344 A1. SUMMARY OF THE INVENTION The invention is defined by the appended claims. The description that follows is subjected to this limitation. Any disclosure lying outside the scope of said claims is only intended for illustrative as well as comparative purposes. In general, when the material slurry for a porous insulating layer is coated on the active material layer, a solvent included in the material slurry may expand the active material layer and thus decrease density of the active material layer. In other words, since the active material layer has a pore after the compression, a part of liquid components of the material slurry permeates into the active material layer when the material slurry is coated. The permeated liquid components have an influence on constituting materials of the active material layer. The electrode after the compression has a residual stress, but the permeated liquid components have an influence on properties of the constituting materials of the active material layer such as elasticity and the like and resultantly, destroy a balance of the residual stress and partly cause a residual deformation and thus increase a thickness of the active material layer. When the thickness of the active material layer is increased larger than a design thickness, there may be a problem in inserting a battery device into an external case. When the active material layer consists of a plurality of layers, each layer may show a small thickness increase, but since the battery device is in general a stack structure formed by stacking a plurality of electrode and a separator or a spirally-wound assembly formed by winding a long electrode, a total layer thickness increase of the plurality of active material layers may cause a problem of increasing a total thickness of the battery device. This problem may be more serious, when the active material layer is compressed with a larger pressure in order to manufacture a high energy density non-aqueous electrolyte rechargeable battery. In other words, when design electrode density (filling rate) of the active material layer is low, the design electrode density of the active material layer may be set to be high in advance of the compression of the electrode by considering a thickness increase of the electrode after forming the porous insulating layer, but since the design electrode density becomes higher according to recently higher energy density of a non-aqueous electrolyte rechargeable battery, the electrode may not be compressed up to higher electrode density than the design electrode density of the active material layer. In addition, when non-oriented graphite particles are for example used as a negative active material battery in a response to a demand on a battery having a long cycle-life, a higher pressure needs to be applied during compression of the electrode. Since the compressed electrode bears a large residual stress and deformation, the thickness increase problem of the active material layer during coating and drying of the material slurry is more and more noticed and thus may be developed up to a production prob