CityU Emerging Technologies Forums look to the future. Speakers from industry and research institutions are invited to talk about the latest government policies, technological trends, local and regional initiatives and product development strategies related to their sectors. The 2nd Forum named “Advances in Battery Technology” held in Innovation Centre, CityU on 5th Jan 2018. In the beginning, I took a photo with Mr. David AI (Director, KTO) (Centre Left) and Ms. YS Chow (Senior R&D Manager – Rechargeable Products, GP Batteries International Ltd.) (Centre Right).
I met EngD cohorts and took a photo for memory.(Left: I, Mr. George Chan (Supplier Quality Manager, Monster Products) and Dr. Samuel Fung (Director, Karson Engineers Services Co., Ltd.))
In the beginning, Prof. Henry Shu-hung Chung gave an opening remark. He introduced the background of Emerging Technologies Forums and introduced guest speaker.
Ms. YS Chow (Senior R&D Manager – Rechargeable Products, GP Batteries International Ltd.) was the first speaker and her topic entitled “Recent Developments in Fast Charging Li-ion Batteries”. Firstly, she briefed GP background and products.
Then Ms. Chow introduced different type of battery classification as follows:
- Primary batteries
- Rechargeable batteries
- Portable PowerBanks
- Carbon Zinc
- Silver Oxide
- Primary Lithium
- Nickel Metal Hydride (NiMH) (Rechargeable)
- Lithium ion (Rechargeable)
By Size: AA, AAA, C, D, 9V, Button Cells and Other Customized Packs.
She said the charging rate was limited by electronics (chargers) and cell chemistry; and there was a huge demand to develop fast-charging electronic and batteries.The commercial available fast charging battery performance was showed as following diagram.
After that Ms. Chow briefed three technologies of fast charging to us and the first one was LiFePO4 technology. She explained the concept of charging that 1C is about 1hr to charge full and 2C is about 0.5hr for full charging. It was available to use 4C charging and upto 65% of capacity in 10 minutes. She said using the high current charging in the beginning and then using low current to fill up the capacity. The smaller participle used the more room for recharge ion. However, this technology had lower energy density (~194Wh/L).
The second technology was LTO battery that used TiO which was 3D charging structure. Traditional, using graphite was multi-layer structure that charging needed to queue. TiO anode is better safety and cycle life than graphite anode but its voltage of the cell and energy density were low.
The third technology was graphene ball by Samsung for Li rechargeable fast charge battery. However, graphene is only single layer that is not enough energy density. They employed graphene to coat on the surface of Silicon oxide using CVD method. In laboratory, Samsung achieved to be charged by 12 min for full capacity and up to 800Wh/L with 500th cycle at 5C charging rate! She added that Samsung product might be launched after several years.
After introduction of existing technology for fast charging, she explained three transportation steps in the cell which caused resistant.
Step A – it represents electrons or ions transport from their reservoir to individual particles.
Step B – it represents surface reaction between Li ion with cathode and anode particles.Step C – it represents transportation of Li ion insides a solid particle.
Ms. Chow explained material synthesis routes as follows:
Route 1: Ball milling to be SiO Particle
Route 2: SiO Particle under chemical grafting to be SiO@Polymer Particle
Route 3: Add Graphite Particle into SiO@Polymer Particle and then spray dry and calcinationShe showed the SEM diagram of nano particles that red color was graphite and blue color was silicon.
Finally, she introduced their new faster cell and their capacity more than 1260 mAh, mid-point voltage to be 3.82V and energy density more than 500 Wh/L. GP technology was at the middle position between energy density and charging speed. However, increase both energy density and charging speed were the future trend of fast charging battery development.
Prof. Henry Chung (Professor and Assistant Head, EE Dept., CityU) was the second speaker and his topic named “An Energy-Efficient Battery Parameter Extraction Technology”. Prof. Chung appreciated the support of EMSD and ITF for this project “Smart Real-time Battery State and Health Diagnostics System” since 2014. Before this project, Prof. Chung studied smart city with emphasis on Energy Utilization.
In his study, there were three parts included Distributed Renewable Source (Generation), Smart Load (Utilization) and Energy Storage (Storage). In this seminar, he focused on Energy Storage. The role of batteries in a Smart City was briefed below.
Energy Storage – Highest energy density among different fuels
System stability and reliability – Sustaining load operation during power outageTypical usage – Data centre, Vehicles and Distributed renewable micro-sources
Then Prof. Chung briefed the failure distributions from diagnosis to statistics on failure rate against the time (years or cycles). There were two approaches on the prior-art battery testing methods that were Off-line (under a controlled environment) and On-line (utilize real-time data to estimate intrinsic parameters). Then he pointed out two key status indicators (SOC and SOH).
SOC: State-of-charge – How much charge remaining in batterySOH: State-of-health referenced by Ro (Internal Resistance) nominal value (battery aged or not)
After that he introduced his Smart Battery Health Monitoring System. The benefits were energy saving, cost saving, reduction of electronic waste and internet connected.
The prototype of Smart Battery Health Monitoring System was demonstrated.
At the end, Prof. Henry Chung briefed KTO support that a bridge between CityU and Industry.
Q&A SessionSome participants asked charging safety and Ms. Chow said rechargeable battery had shut down function when over heat. Overcharging would shorter the life of battery because of aging due to solid electrolyte interphase (SEI) layer growth.
CityU KTO - http://www.cityu.edu.hk/kto/https://www.hkstp.org/en