Laminated Lion ion batteries - LaminaLion

Today?s modern society depends on lithium-ion batteries, which currently are used to power an increasingly diverse range of applications from large ships down to microchips. Safer batteries with high capacities and improved power capabilities are needed for future applications, and 3D structured all-solid-state batteries is one approach that could fulfil these demands. The aim of the present project is to manufacture such 3D structured all-solid-state batteries. The thin film deposition process called atomic layer deposition (ALD) enables, through its self-controlling nature and atomic precision, realization of such a complex battery. This battery contains no poisonous or dangerous liquid electrolytes that are found in today?s lithium-ion batteries making it completely safe. In addition, the 3D-strucutred electrodes together with a nanostructured solid state electrolyte should enable the battery to be fully charged or discharged in minutes. The current results have been to develop ALD processes for all the all-solid-state battery components, namely the cathode, electrolyte and anode. For the cathode, a process have been developed for the material LiMn2O4 which displays almost no volume change as lithium ions are inserted and extracted from the electrode during discharging and charging, a feature of great importance in a all-solid-state battery. For the electrolyte, an ALD process have been developed for the material Li2CO3, which then have been studied when used as a composite solid-state electrolyte together with an organic polymer. For the anode, an ALD process have been developed for the material Li4Ti5O12 , another material that exhibits almost no volume change during charging and discharging.

For the application of durable micro-storage for autonomous systems and implants, 3D thin-film batteries are leading candidates. Lithium ion batteries have the highest energy density of all known systems and are thus the best choice for these rechargeable micro-batteries. Since liquid electrolyte based batteries present safety issues and limitations in size and design, pure solid state devices are considered particularly for miniaturization. The thin-film concept provides the means for good ionic conducta nce through reduction of the distance for Li-ion diffusion. Combined with the large surface area of a 3D structured surface (e.g. etched pillars or nanowires) an acceptable battery capacity is maintained as the total electrode volume is preserved by the i ncrease in effective surface. Remaining technological issues are (i) the mechanical strain induced in the rigid solid stack during charge/discharge which limits the life time of the battery and (ii) pinholes in the films which limits their minimum thickne ss and as such the battery power (ionic conductance). The main objective of this project is to develop a mechanically flexible solid electrolyte in the form of a conformal thin-film stack which is to be used for 3D thin-film solid-state lithium-ion batter ies. The success of this objective is measured through the durability (cycle life time) of a 3D thin-film micro-battery demonstrator. The second objective is to obtain pinhole-free thin-films constituting a thin-film electrolyte stack with total thickness down to 100nm or less to achieve good ionic conductance. The success of this objective is measured through the performance of the planar and 3D thin-film micro-battery demonstrators. These objectives will be achieved through the application of ALD/MLD pr ocesses. Our final goal is a functional battery stack with fast charging/discharging kinetics and long cycle life time.