Question

1. List anode usually used in thin film solid state battery

2. List cathode usually used in thin film solid state battery

3. List electrolyte usually used in thin film solid state battery

4. What is the depositing method of the cathode material and how it works? What is the depositing method of the anode material?

5. Simply describe the layer configuration of a thin film solid state battery.

answer all the 5 questions

solid battery

Answer 1

1. Anode is made up of carbon based material such as graphite. Lithium and other metals can also be used as anodes.

2. The cathode of a thin film battery is made up of a lithium oxide complex such as LiCoO₂, LiMn₂O₄ and LiFePO₄.

3. The most common solid electrolyte used is lithium phosphoris oxynitride (LiPON). Ceramic materials such as lithium lanthanum zinc oxide (LLZO) and lithium lanthanum titanium oxide (LLTO) are also used as elctrolyte in a thin film solid state battery.

4.The depositin method for cathode depostion is Atomic Layer Deposition (ALD). Its most distinctive feature is that it has self limiting growth, and each time one molecular layer can grow hence, it offers a good method for depositing films having thickness in the nanometer range. In an ALD process, the surface is first activated with by a chemical reaction. The ALD reaction between VO(OC₃H₇)₃ (VTOP) and O₃ produces crystalline V₂O₅ at 170⁰C. We then employ electrochemical lithiation as a conformal technique to rapidly transform the deposited V₂O₅ through the reaction V₂O₅ + Li⁺ e- → LiV₂O₅ in a LiClO4/propylene carbonate electrolyte, which can then be incorporated into a full solid state battery.

The use of Li metal is currently ruled out for lack of a plausible ALD process. Thus, any all-ALD conformal solid state battery (SSB) will be a Li-ion cell. Deposition on the anode can be done by Chemical vapor infiltration (CVI) which involves the deposition of solid products onto a porous medium. Its primary aim is to fill voids in porous graphite and fibrous mats to prepare carbon–carbon composites.

5. Thin film batteries are a type of solid state batteries .i.e. both the electrodes (anode & cathide) as well as the electrolyte are in the solid state with a thickness of a few hundred nanometers.

When the battery is being charged, the lithium ions migrate from the lithium rich cathode and move into the anode. When the battery is in this state, it will absorb energy that can then be stored. If the battery is turned on during charging, the lithium ions will move back to the cathode and electrons will move from the cathode to the anode (although not through the electrolyte) and a current between the two electrodes is created.

When the battery is not being charged, it is in a state known as discharging. The lithium ions move from the anode to the cathode (i.e. discharge) and electrons will travel from the cathode to the anode. The time it takes for the ions to completely discharge is the current life of the battery, and when all the lithium ions have returned to the cathode, the battery will run out of power because the electrons will not migrate if there is no lithium ion movement. Thus, the battery will need to be charged again. If the battery is in a product that can be switched off, it will still discharge while the device is switched off, but at a much slower rate.