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:
By Nature:
-
Primary batteries
-
Rechargeable batteries
-
Chargers
-
Portable PowerBanks
By Chemistry:
-
Alkaline
-
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 calcination
She 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 outage
Typical 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 battery
SOH: 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 Session
Some 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.
Reference:
CityU
KTO - http://www.cityu.edu.hk/kto/
HKSTP - https://www.hkstp.org/en
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