Rechargeable Li-ion batteries have been employed to power various portable electronics, such as mobile phones, digital cameras, laptops and iPads that have changed our communication in the modern society. Now the finite supply of fossil fuel and the increasing global warming as a subsequence of greenhouse gas emission have promoted the development of green and sustainable energy resources. The combination of rechargeable batteries and supercapacitors has been considered as a very promising candidate. Due to their high energy density and power density, Li-ion batteries are prominent in rechargeable battery systems. Despite the continuously impressive development of Li-ion battery technique, it still can’t fully satisfy the industrial demand. There is a great challenge to improve the performance of Li-ion batteries to meet the requirements of applications including electric vehicles, grid station and et al.
Chapter 1 begins with a general introduction of Li-ion battery fundamentals, followed by the historical development of the anode, the cathode and the electrolyte, and ended up with the objectives of this thesis.
Chapter 2 generally introduces the experimental techniques used in this thesis including the routine structure characterizations and the electrochemical characterizations as well as battery fabrication procedures associated with Li-ion batteries.
In Chapter 3, we have demonstrated the successful synthesis of an aromatic acid based sp3 boron single-ion polymer electrolyte (SIPE), LiPPAB, based on the polymerization reaction of the silylated aromatic acid and lithium tetramethanolatoborate in DMF. The as-synthesized product was purified and well characterized. The electrochemical performance of LiPPAB was fully investigated and discussed.
In Chapter 4, an aliphatic acid was used to synthesize sp3 boron SIPE with a similar synthesis procedure. The obtained SIPE, LiPBAB, exhibits improved electrochemical performances in term of ionic conductivity, lithium-ion transference number and battery performances compared to the aromatic acid based SIPE LiPPAB.
In Chapter 5, the direct polymerization of the phenol and lithium tetramethanolatoborate in DMF was achieved, simplifying the synthesis procedure compared to the carboxylic acid precursors. It turned out that this phenol based SIPE possessed even better battery performance.
In Chapter 6, a sp3 aluminium based SIPE was designed and synthesized considering the successful synthesis of boron based SIPEs. The obtained SIPE exhibits slightly inferior electrochemical performances compared to the boron based SIPEs probably because of the high rigidity of aluminium based polymer chain.
Chapter 7 gives the general summary of the presented works in this thesis and outlook in the future. SIPEs are still in the initial stage, there is a long way to go.
|School:||National University of Singapore (Singapore)|
|School Location:||Republic of Singapore|
|Source:||DAI-B 77/06(E), Dissertation Abstracts International|
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