Cathode Materials for Sodium-ion Batteries
Just as is the case with lithium-ion batteries, cathode materials are a key component of Sodium-ion batteries. The composition of the cathode material determines the cell voltage and capacity, and thereby the energy density. Sodium-ion cathode materials are typically based on intercalation / de-intercalation compounds, where sodium ions provided by the cathode are inserted into the host lattice (anode) during charge and extracted during discharge, with minimal structural change in the host material.
In contrast to lithium, sodium is one of the most abundant elements in the earth’s crust. Consequently, Na-ion batteries have attracted much attention over the past few years. The choice of cathode material with a particular chemistry depends on various factors, including cell voltage, capacity, energy and power capabilities, cycle life, and temperature of operation.
NEI can provide a variety of custom synthesized Na-ion cathode materials upon request (some examples are shown below):
|Cathode Material Type||Composition||Nominal Voltage vs. Na||Advantages||Applications||Nominal Capacity at 0.1C|
|Na3MnPO4CO3||~3.3 V||High energy||Portable electronics and electric vehicles||191 mAh/g (theoretical)|
(M= Co, Fe, Mn, Ni)
|~3.2V||Comparable power to that of LiCoO2||Power tools||~110 mAh/g|
(Olivine Type) Phosphates
(M=Fe, Mn, Co, Ni)
|~3.0V||High energy||~120 mAh/g|
|Na2FePO4F||~2.97V||Comparable power to that of LiCoO2||Portable electronics||~110 mAh/g|
Na-ion Polymer-based Solid Electrolytes
NEI provides solid polymer electrolytes for rechargeable solid-state sodium batteries. The electrolytes are based on low lattice energy sodium salts (e.g. NaTFSI), dissolved in polyether-containing polymers such as poly(ethylene oxide). One of the polymers developed at NEI Corporation using the copolymer strategy is H-polymer. As a 100% solid material, H-polymer combines the benefits of high room temperature ionic conductivity with good mechanical properties of a solid polymer.