Lithium salt unleashes 93% retention breakthrough in sodium-ion battery tech
Researchers in Korea have developed a method to improve the lifespan and performance of sodium-ion batteries (SIBs) by introducing a lithium salt into the battery’s electrolyte.
The study shows that adding lithium hexafluorophosphate (LiPF6) to the electrolyte resulted in a battery that retained 92.7% of its capacity after 400 charge-discharge cycles. This is an improvement over the typical 80% retention previously reported for similar batteries.
“The addition of LiPF6 to the electrolyte significantly improves the formation of a robust SEI layer on the hard carbon anode,” said the researchers in a press release.
“The scalable synthesis of the LiPF6-added electrolyte highlights its potential for practical SIB applications.”
Addressing key challenges
The work, conducted by a team from the Korea Electronics Technology Institute (KETI) and Kangwon National University, addresses known issues of cycle stability and capacity fade in SIBs.
Sodium-ion batteries are being explored as an alternative to lithium-ion technology. An advantage of SIBs is the global abundance and lower cost of sodium compared to lithium.
This could make them suitable for large-scale energy storage, which is needed to support renewable energy sources. However, the commercial development of SIBs has faced challenges related to the degradation of battery components over time.
A dual-action process
According to the research led by Professor Ji-Sang Yu and Professor Hyun-seung Kim, the lithium salt additive alters the battery’s internal chemistry through a dual-action process.
Firstly, for anode protection, the presence of lithium salt facilitates the formation of a more stable solid electrolyte interphase (SEI) on the hard carbon anode. This protective layer is less soluble than a standard sodium-based SEI, thereby reducing the decomposition of the electrolyte.
Secondly, for cathode reinforcement, the lithium ions dope the surface of the O3-type cathode, creating what the researchers term “Li-ion pillars.”
“The slight surface doping of the O3-type cathode with Li ions creates a structural reinforcement that serves as a pillar, preventing the collapse of the layered structure and reducing gas evolution during cycling,” asserted the press release.
“The formation of a robust SEI layer and the stabilization of the O3-type cathode surface significantly improve cycleability and capacity retention.”
Anode protection and cathode reinforcement
Analysis using differential electrochemical mass spectrometry showed a reduction in CO2 gas evolution, an indicator of electrolyte degradation.
Post-cycle examination with microscopy techniques revealed a preserved cathode structure and a stable SEI on the anode.
The researchers state that the scalable synthesis of this electrolyte suggests a path toward practical applications for sodium-ion batteries.
This study contributes to the ongoing development of cost-effective sodium-ion battery technologies for a more sustainable energy future.
“The insights gained from this study can guide the development of more efficient and cost-effective sodium-ion battery technologies,” concluded the press release.
“Future work may focus on exploring other additives and electrolyte compositions to further enhance the performance and stability of SIBs.”
Source: Interesting Engineering
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Lithium salt unleashes 93% retention breakthrough in sodium-ion battery tech