Packing light: Lightweighting car batteries

Given that the battery accounts for more than half of the overall weight of electric cars, battery makers are trying out a variety of different strategies — from new chemicals to new business models — to bring down the weight of the batteries.

By Amit Vijay M calendar 06 Jun 2024 Views icon4912 Views Share - Share to Facebook Share to Twitter Share to LinkedIn Share to Whatsapp
Packing light: Lightweighting car batteries

As the electric vehicle (EV) revolution gains momentum in India, battery manufacturers are faced with the critical challenge of reducing the weight of their batteries to increase energy density, extend range, and lower costs. Indian original equipment manufacturers (OEMs) and independent battery makers are rising to this challenge, embracing innovative materials and technologies to create lighter, high-performance batteries.

The importance of battery lightweighting cannot be overstated. As R&D executives and industry CEOs recently discussed at the Autocar Professional Vehicle Lightweighting Conference, battery packs currently occupy nearly 50-60% of a vehicle's space and contribute even more to the vehicle’s overall weight, making them 20–30% heavier compared to conventional vehicles. The common goal is to produce lightweight, high-performance batteries to address this issue. Battery makers are following multiple strategies to address the issue of weight. First, many of them are trying to change the chemical composition of the batteries, trying to introduce materials that have a greater power-to-weight ratio.

A second method being tried out is around the battery pack itself, with OEMs trying lighter components to fix the battery in place, instead of the traditional metal enclosures, clamps, and so on. Finally, they are also trying to address the problem of battery size by addressing the underlying concern of range, by introducing swappable batteries.

Innovating with battery chemistries

The first, and possibly the most obvious method, is to try to innovate around the chemistry of the battery to come up with more power-efficient technologies. A case in point is the partnership between India’s Omega Seiki Mobility with Bengaluru-based EV battery manufacturer Exponent Energy to build high-performance battery packs. This, the Indian company says, has enabled their electric three-wheeler OSM 'Stream City Qik' passenger vehicle to achieve a range of close to 126 kilometers on a much smaller 8.8 kWh battery pack compared to its peers.

Chairman and Founder Uday Narang, is aiming for even greater efficiency in the future.

"Our future batteries will be designed to increase the specific energy of the battery pack by about 50% while reducing production costs by 30%, which is our long-term target for future models. We are aiming to develop future batteries that are about 40% lighter, resulting in increased range and smaller battery pack size," he said.

Gurugram-based Batx Energies is adopting a different strategy — that of eliminating cobalt and nickel from the batteries. These cells, known as LFP batteries, are expected to have higher energy density. "We are looking to develop high-capacity anode materials like silicon and advanced cathode materials such as high-nickel compositions, innovative electrolytes, including solid-state and gel-based variants, to improve safety and energy density," said Vikrant Singh, Co-founder and Chief Technology Officer of Batx Energies.

Meanwhile, others claim to have made great strides on the LFP front, including Bengaluru-based Oben EV. The company’s flagship product — Oben Rorr electric motorcycle — has a 4.4 kWh LFP battery that delivers a claimed range of 180+ km for their mass market premium electric bike. The company is working on advanced versions of smaller LFP batteries which will have a high energy density, meaning they can store a large amount of energy in a relatively small space, said  Madhumita Agrawal, CEO and Founder at Oben.

Randheer Singh, CEO and Director of ForeSee Advisors and a former Director of Electric Mobility at the Government of India's NITI Aayog, is advising one of India's major conglomerates on its transition to electric mobility for its upcoming battery gigafactory in North East India.

Singh says, "Several EV OEM and battery makers are in the advanced stages of introducing solid-state batteries with two or three times higher energy density than lithium-ion batteries while being 30-40% lighter."

A 'weighty' issue

Besides experimenting with newer materials, battery makers and OEMs are also trying to shave off some extra weight by coming up with alternative housing for the battery, or even getting rid of it altogether.

According to Singh, some of the battery vendors are attempting to include structural components within battery packs, potentially leading to savings of up to 20 kg per vehicle.

Delhi-based Okaya Power Group, which entered the EV space in 2020 with Okaya Electric two-wheelers, is trying out various materials for its battery enclosures. “We are looking at polymer enclosures that will support electromagnetic interference (EMI) shielding and offer the highest fire protection while fulfilling the core objective of getting the most mileage from a single charge," said Okaya Electric's Director, Anshul Gupta.

Battery enclosures traditionally made from aluminium are now transitioning towards lighter composite plastics, as seen in models like BMW's iX and General Motors' Chevrolet Bolt EV.

Thanigesh Arumugam Parthsarathi, Research Analyst Mobility at Frost & Sullivan, pointed out that Tesla's 4680 battery and BYD's Blade Battery are driving advancements in lightweighting and offering superior sealing capabilities and flame-retardant properties.

Even as some players are trying to come up with lower weight enclosures for the batteries, others are considering a more drastic step — totally eliminating metallic enclosures altogether. This battery technology,  according to Duraibabu Sreenivasan, Regional SBU Head — IMEA AMC, and Gurmeet Kaur, Country Head, Henkel Adhesives Technologies India, shows a shift first from "Battery Module to Pack" to "Cell to Pack" and then "Cell to Chassis." Some OEMs have already made EVs with cells woven into composite bonded panels while others have successfully contributed to the industry's lightweighting targets by using say, nominal 2.2 pounds (~998 grams) of adhesives instead of heavier rivets and welds, thereby helping reducing a vehicle's overall weight by 55 pounds (-25 kgs).

Doing away with big batteries

It is not just the chemistry of the cell and the structure of the enclosures that companies are tinkering with, to get rid of excess weight. Some are attacking the problem from a very different angle. Instead of trying to make batteries lighter, they are trying to eliminate the need for huge batteries altogether. This is being sought to be done by making it as simple to swap a depleted battery.  The flip side is that most of the current EVs (especially 4-wheelers) have fixed batteries that cannot be detached from the vehicle.

'Charging' forward

India's Battery Production Linked Incentive (PLI) initiative aims to accelerate battery lightweighting as new industry players, including ACME Cleantech Solutions, Amara Raja Advanced Cell Technologies, Anvi Power Industries, JSW Neo Energy, Lucas TVS, and Waaree Energies, have bid for incentives totaling Rs 3,620 crore to expand battery capacity by 10 Gigawatt hours.

Additionally, Ola Cell Technologies, Rajesh Exports, and Reliance New Energy Battery Storage have been awarded 30 GWh of bandwidth will focus on lightweighting.  Says Randheer Singh, as government has tapered the subsidies, EV makers will automaticlaly move towards higher energy density and lower weight battery packs.

Mattter Group's Mohal Lalbhai says that the Government of India's Battery PLI scheme will help accelerate the development of lightweighting with the entry of newer players experimenting with new cell chemistries, manufacturing indigenous cells, and manufacturing facilities that will provide battery manufacturers with an end-to-end supply chain, as the majority of cells are currently imported from other Asian countries. Singh also emphasised the implementation of AIS 156 Part 2, which has seen the emergence of connected batteries with RFID tags and is set to prioritise lightweighting while adhering to aspects such as protecting battery packs from overcharging and thermal runaway, ensuring environmental resilience, mechanical integrity, ageing, and performance under a variety of conditions.

This feature was first published in Autocar Professional's June 1, 2024 issue.

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