Lithium Polymer Batteries

Published on 22 Nov, 2013

Lithium polymer batteries, or LiPo batteries, are secondary cells that find application in mobile electronics, laptops and radio-controlled equipment. With an increase in research focus, LiPo batteries are expected to power next-generation battery electric vehicles.

LiPo batteries

LiPo batteries are an advanced version of lithium-ion batteries. Although the chemical composition of the anode and cathode in both types of batteries is the same, the main difference is in terms of the separator used. Lithium-ion batteries use an inert substance with holes covered in electrolyte, while LiPo batteries use micro-porous polymer covered in an electrolytic gel as a separator. LiPo batteries offer several advantages over lithium ion batteries.

  • High energy density due to the use of a polymer as a separator that reduces energy barrier in the chemical reaction between the anode and cathode.
  • Batteries can be moulded into several shapes and can also be reduced to thin films due to the flexibility of the solid polymer.
  • LiPo batteries are fully charged at 4.2 volts and are considered fully discharged at 3.0 volts, thereby allowing a relatively flat voltage discharge curve and provide solid performance throughout the discharge cycle.
  • LiPo batteries have reduced self heating due to low internal impedance.
  • LiPo batteries enhance safety as the chances of an electrolyte leakage are lower due to a no-liquid electrolyte.

Factors such as high manufacturing cost and less capacity over lithium-ion batteries pose a challenge for LiPo batteries.

Figure 1: Filing Trend

Lithium Polymer Batteries Filing trend

Source: Aranca analysis based on Thomson Innovation data)

LiPo battery is an attractive research area with more than 6000 patents filed in the last five years. The research has been primarily driven by the widespread application in the electronic sector, which is growing at an exponential rate every year.

Figure 2: Origin Of Invention & Jurisdiction Spread

Origin of Invention Lithium Polymer Batteries

Source: Aranca analysis based on Thomson Innovation data)

Japan, a forerunner in the battery business, ranks first in terms of research innovation in LiPo batteries followed by China, Korea and the US. Additionally, and Korea are the prime markets due to the presence of most large companies in the mobile phones, laptops and other electronics space.

Figure 3: Competitive Landscape

Lithium Polymer Batteries Competitive Landscape

Source: Aranca analysis based on Thomson Innovation data)

The competitive landscape indicates most electronic companies are leaders in the innovation of LiPo batteries due to its advantages vis-à-vis other conventional batteries. The most active assignees are Toyota, Samsung, LG, Hitachi and Panasonic. The research focus of these companies is mainly leading to an improvement in battery capacity, flexibility, safety and charging & discharging efficiency. Some approaches to develop these characteristics are:

  • Addition of an electrolyte material along with gelled polymer; for example, use of ceramic solid electrolyte;
  • Research related to effective polymers to improve the characteristics mentioned above; and
  • Innovations around the anode and cathode composition.