Mixed Phase P2/O3 Oxides for use in Sodium-ion Batteries

University of St. Andrews Background
With an increasing need to integrate intermittent and unpredictable renewables, the electricity supply sector has a pressing need for inexpensive energy storage. There is also rapidly growing demand for behind-the-meter (at home or work) energy storage systems. Sodium-ion batteries (SIBs) are attractive prospects for stationary storage applications where lifetime operational cost, not weight or volume, is the overriding factor. Recent improvements in performance, particularly in energy density, mean SIBs are reaching performance levels suitable for commercial scale-up.
In addition, the rapid growth of lithium-ion batteries (LIBs) is creating supply issues for key elements such as lithium, nickel, copper and cobalt, which are not homogenously distributed within the Earth’s crust, and suffered significant price volatility in recent years. Furthermore, elements such as nicklel and cobalt are toxic, and cobalt has significant ethical issues asscciated with the use of child labour in the extraction processes. Therefore, it is crucial to develop alternative energy storage technologies which are free of these elements to provide solutions which are truly sustainable, low cost and non-toxic.
Technology Overview
Even though SIBs offer meaningful material cost advantages, improvement performance is critical. Enhanced battery energy density and cycle life are needed to greatly increase the commercial attractiveness of SIB technology. Current and near-commercial SIBs positive electrode materials contain nickel, which suffer from high cost, potential supply chain issues and toxicity concerns.
St Andrews inventors have developed a series of materials with varied O3:P2 ratios, from pure phase O3 to O3/P2 bi-phasics to pure phase P2 based exclusively on elements, which are Earth abundant. These materials demonstrate high energy density, long cycle lifetimes and good rate capability. Crucially, changing the O3:P2 ratio allows for the tuning of performance parameters such voltage window, energy density, cycling stability and rate capability. This approach enables rational design of low-cost positive electrode materials using the same chemistry for different applications (e.g. high energy or high power) simply by tuning the O3:P2 ratio.
In comparison to lithium-ion batteries:

Lower cost using widely available and inexpensive raw materials
Enhanced safety
Greater sustainability
Potential performance advantages
Scalable based on existing lithium-ion production methods

Early Applications: Where high power is advantageous (e.g. power tools) and in early-stage uninterruptible power supply applications in the telecommunications sector.
Near-term Applications: Replacement of diesel generators where there is no electricity network or where the network is unreliable. such as community mini-grids and home solar systems. Can be integrated in community mini-grids and home solar systems.
Future Applications: Replacement of lead-acid batteries
The university is interested in licensing opportunities and to hear from commercial or development partners.

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