SCIENCE & TECH/ ECONOMY
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Breakthrough in battery tech
Context: Shareholders of California-based QuantumScape Corp, a battery startup backed by Volkswagen AG, have approved a multibillion-dollar pay package for CEO Jagdeep Singh, who could receive stock options potentially valued at $2.3 billion, subject to the company meeting some performance milestones.
A quantum leap
- QuantumScape’s solid-state battery — lithium metal with a solid electrolyte separating the two electrodes — is seen as an exceptionally bright prospect in an increasingly crowded space.
- The company, which was co-founded by Singh a decade ago was valued at almost $50 billion on the promise that its novel battery technology could offer a safer, cheaper alternative to lithium-ion batteries.
- Earlier efforts to build a solid-state separator (electrolyte) capable of working with lithium metal had to compromise on aspects such as the cycle life and operating temperature of the battery, and the issue of excess lithium deposits on the anode.
- QuantumScape claims to have circumvented this: its use of a solid state separator technology eliminates the side reaction between the liquid electrolyte and the carbon/graphite in the anode of conventional lithium-ion cells.
- This technology could make car batteries cheaper, more reliable and quicker to recharge.
- Volkswagen plans to have production running for solid-state batteries by 2025 via the partnership with QuantumScape.
What are the challenges with lithium-ion batteries?
- The energy density of lithium-ion cells used in today’s mobile phones and electric vehicles is nearly four times higher than that of older-generation nickel-cadmium batteries.
- Lithium-ion batteries use aqueous electrolyte solutions, where ions transfer to and fro between the anode (negative electrode generally made of graphite) and cathode (positive electrode made of lithium), triggering the recharge and discharge of electrons.
- Despite improvements in technology over the last decade, issues such as long charging times and weak energy density persist.
- While lithium-ion batteries are seen as sufficiently efficient for phones and laptops, they still lack the range that would make EVs a viable alternative to internal combustion engines.
- One major problem is that lithium metal is extremely reactive. The main form of lithium corrosion are dendrites, which are branched lithium structures that grow out from the electrode and can potentially pierce through the separator and on to the other end, short-circuiting the cell.
- In current lithium-ion batteries, in which the electrolyte is a flammable liquid, dendrite formation can trigger a fire.
What is the innovation in Solid-State battery developed by QuantumScape?
- QuantumScape says its solid-state lithium-metal battery replaces the polymer separator used in conventional lithium-ion batteries with a solid-state separator.
- The replacement of the separator enables the use of a lithium-metal anode in place of the traditional carbon/graphite anode.
- The lithium metal anode is more energy-dense than conventional anodes, which allows the battery to store more energy in the same volume.
What are the advantages of Solid-State batteries?
- The advantages of the solid-state battery technology include
- Higher cell energy density (by eliminating the carbon anode)
- Lower charge time (by eliminating the need to have lithium diffuse into the carbon particles in conventional lithium-ion cells),
- Ability to undertake more charging cycles and thereby a longer life,
- Improved safety.
- Lower cost could be a game-changer, given that at 30 per cent of the total cost, battery expenses are a key driver of the vehicle costs.
- Lithium-ion battery costs are currently about $137 per kWh, and are expected to reach $101/kWh by 2023. QuantumScape claims it is targeting to lower battery cost by 15-20% relative to the cost of lithium-ion batteries in several years.