Next Generation Sodium-Ion Batteries: Patent Landscape Study

Let’s go through a Patent Landscape Study on Next Generation Sodium-Ion Batteries. The concept of electrochemical batteries is not new to this world. A large number of batteries having different material combinations and performance characteristics are available in the market. However, lithium-ion batteries (LIBs) still lead in the market. LIBs have already become the battery of choice for many electrical energy storage systems, ranging from mobile phones to powering electric vehicles (EVs) because they provide the highest energy density than any other available battery for rechargeable devices.

But developing a battery with same storage capacity and performance characteristics at a price costing less than 80 percent than that of a high-performance Lithium-ion battery is flabbergasting. Isn’t it?

Recently, Stanford researchers developed next generation sodium-ion batteries based on a compound related to table salt in which sodium and myo-inositol enabled the efficient electron flow between the electrons thus boosting the performance of next generation sodium-ion batteries significantly. “Nothing may ever surpass lithium in performance,” Chemical engineer Zhenan Bao said. “But lithium is so rare and costly that we need to develop high-performance but low-cost batteries based on abundant elements like sodium.” However, till now researchers had focused solely on cost-performance comparisons between their sodium ion battery and state of the art lithium. In the future they’ll have to look at volumetric energy density – how big must next generation sodium-ion batteries be to store the same energy as a lithium ion system.

An attempt is made in determining the true potential of sodium-ion batteries as an alternative to lithium-ion batteries on grounds of:

  • High energy storage capacity;
  • Compact size;
  • Low cost; and
  • High efficiency

The patent landscape analysis shows a gradual increase in the number of patents filed in this technology domain till 2017 with an average growth rate of 20.7% per year. These researches have been carried out mainly in China, the US, Japan, South Korea and Germany, with China leading the way in sodium-ion batteries. In 2015, Faradion, a leading player providing next-generation, low-cost materials that are employed in sodium-ion batteries collaborated with Sharp Corporation, a leading global specialist in solar energy solutions and filed 3 patents in collaboration for developing energy storage systems for small renewable energy harvesting and power generation systems. In 2017, several new entrants such as Ningbo Jidianxin New Material Technology, Suzhou Sichuangyuanbo Electronic Technology, Dongguan Jiaqian New Mat Technology and China Electronic New Energy Research Institute have filed their patents focusing mainly on electrode and electrolyte materials in sodium-ion batteries.

Through the analysis of all patent literatures in this technology domain, it is evident that researchers are focusing mainly on using carbonaceous material such as hard carbon and graphene for making anode of sodium-ion batteries. Other materials like transition metal oxides, transition metal sulfides, transition metal phosphides, binary-metallic compounds, organic compounds, metallic sodium are also disclosed in these patents. From 2008, significant patents have been filed in improving the sodiation/desodiation mechanism and improving the electrochemical performance of such materials. Initially, a few patents disclosed the use of metallic sodium as an anode material but due to several technical challenges such as dendrite formation, high reactivity and an unstable passivation layer, metallic sodium is not preferred for anode in sodium ion-batteries.

Most of the patents had disclosed the use of sodiated transition metal oxides for making cathode of sodium-ion batteries. Among the electrolyte materials, organic electrolytes are highly focused using mostly propylene carbonate and ethylene carbonate or a combination of both as an organic solvent, and sodium perchlorate and sodium hexafluorophosphate as a salt. After 2004, a significant focus has been seen in making solid electrolyte for sodium-ion batteries.

Furthermore, the IP filings have also determined that nothing has replaced vinylene carbonate, fluoroethylene carbonate and transdifluoroethylene carbonate as an additive in electrolyte. Materials like polyethylene, polypropylene, polyvinyl chloride, polytetrafluoroethylene and glass fiber are used as a separator, with glass fiber leading the way.

Among the most active players in the domain are:

Through the analysis of all patent filings done in this technology domain, it can be inferred that the major focus of all inventions lies in:

  • improving the properties of electrode materials
  • improving the conductivity of electrolytes
  • improving the charge-discharge cycle performance
  • improving the method of manufacturing sodium-ion batteries
  • reducing the dendrite formation
  • improving the mechanical stability of SEI layer

As the Li-ion systems are expected to stay more expensive, it is proposed to replace the lithium by sodium that is cost-effective. Among the various energy storage technologies, sodium-ion battery is a promising method for large-scale storage of electricity due to its flexibility, high energy conversion efficiency, and simple maintenance. Also, the availability of wide range of materials unlocks great opportunities for further research in chemistry around electrodes and electrolytes for sodium-ion batteries. Until then, few questions need to be addressed surrounding sodium-ion batteries:

  • Can sodium-ion batteries ensure a driving range of 500 km to 1,000 km in electric vehicles?
  • Can mass energy storage systems (battery farms, for instance) leverage the low-cost sodium batteries?
  • Will sodium-based batteries be able to match the versatile applications of lithium-ion batteries?

-The Engineering and Editorial Team

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