Solid state battery apparatus

A method of using a solid state battery which comprises:

• a cathode electrode;
• an anode electrode comprising an anode active material:
• first particles comprising silicon, and
• second particles comprising a tin-lithium alloy, wherein a weight concentration of tin in the tin-lithium alloy is greater than a weight concentration of lithium in the tin-lithium alloy;
• and
• a solid electrolyte positioned between the cathode electrode and the anode electrode and configured to enable transport of lithium ions between the cathode electrode and the anode electrode, wherein the solid electrolyte is in contact with at least a portion of the second particles,
• wherein the first particles and the second particles individually form discrete domains in the anode electrode as opposed to forming a combined domain comprising silicon and the material,
• wherein the second particles are substantially softer than the first particles and configured to compensate for size changes of the first particles during charging and discharging cycles of the solid state battery such that, as the first particles expand in size, the second particles are compressed in size at a given pressure applied to the solid state battery and further such that, as the first particles shrink in size, the second particles expand in size at a given pressure applied to the solid state battery, whereby the second particles generally maintain contact with one another and further with the first particles directly or indirectly, which allows the solid state battery to operate at a substantially lower pressure applied thereto than one that would be required in the absence of the second particles in the anode,
• wherein the second particles and the first particles form a bimodal distribution in the anode electrode, wherein the bimodal distribution is configured to reduce porosity of the anode electrode as the second particles are positioned in void space in a lattice of the first particles, the bimodal distribution increases surface contact during charging and discharging cycles of the solid state battery such that the second particles generally maintain contact with one another and further with the first particles directly or indirectly, which allows the solid state battery to operate at a substantially lower pressure applied thereto than one that would be required in the absence of the bimodal distribution in the anode, and
• wherein a pressure under 10 MPa is applied to the solid state battery,
• wherein the method comprises:
• repeatedly charging and discharging the solid state battery, wherein the anode electrode is in direct contact with the solid electrolyte and the direct contact is substantially maintained after the charging and discharging by compensating for size changes of the first particles by using the second particles.

A method of manufacturing a cell of a solid state battery, the method comprising:

• depositing a cathode layer;
• depositing a solid electrolyte layer;
• combining first particles and second particles to form a mixture, the first particles comprising silicon and the second particles comprising a material configured to form an alloy with lithium, wherein the anode does not include carbon-based particles, sulfur-based particles, or oxide-based particles, wherein the second particles are substantially softer than the first particles;
• and
• depositing the mixture in an anode layer such that the second particles are configured to compensate for size changes of the first particles during charging and discharging cycles of the solid state battery such that, as the first particles expand in size, the second particles are compressed in size at a given pressure applied to the solid state battery and further such that, as the first particles shrink in size, the second particles expand in size at a given pressure applied to the solid state battery, whereby the second particles generally maintain contact with one another and further with the first particles directly or indirectly, which allows the solid state battery to operate at a substantially lower pressure applied thereto than one that would be required in the absence of the second particles in the anode layer,
• wherein the second particles and the first particles form a bimodal distribution in the anode layer, wherein the bimodal distribution is configured to reduce porosity of the anode layer as the second particles are positioned in void space in a lattice of the first particles, the bimodal distribution increases surface contact during charging and discharging cycles of the solid state battery such that the second particles generally maintain contact with one another and further with the first particles directly or indirectly, which allows the solid state battery to operate at a substantially lower pressure applied thereto than one that would be required in the absence of the bimodal distribution in the anode;
• and
• configuring the solid state battery such that the solid electrolyte layer is positioned intermediate the cathode layer and the anode layer in order to enable transport of lithium ions between the cathode layer and the anode layer,
• wherein the first particles and the second particles individually form discrete domains in the anode layer as opposed to forming a combined domain comprising silicon and the material.