ISCF Wave 1: Improved lifetime performance and safety of electrochemical energy stores through functionalization of passive materials and components

High-performance batteries had disruptive impact in the electronics sector, are pivotal in electrifying transport, and will play a crucial role in grid-scale storage solutions. In particular, Li-Ion and Na-Ion batteries are set to facilitate greater and more efficient use of renewable energy. Application demand for highest possible energy density and power, however, necessitates volatile chemistries and careful consideration of safety aspects as a number of high-profile battery accidents have made strikingly clear in recent years. The most catastrophic failure of Li-ion battery systems is a cascading thermal runaway. Thermal runaway can occur due to thermal, electrical, or mechanical abuse. It can result in the venting of toxic and highly flammable gases and the release of significant heat, potentially leading to explosions and severe damage to the battery, surrounding equipment and/or people.

This project will provide materials technologies to physically safeguard Li-Ion and Na-Ion batteries against thermal runaway and thermally accelerated degradation, superseding existing external safety measures. Rather than changing the active material on the positive side, we will replace conductivity additives, an otherwise passive component of the electrodes, with smart materials. Electrical resistivity of the smart additives will increase by orders of magnitude at or above temperatures where it would otherwise be unsafe to operate the battery. As a consequence, uncontrolled electrochemical reactions, the initial heat source in a thermal runaway event, will cease, making electrochemically initiated thermal runaway impossible.

The approach has several advantages:
(1) it provides a drop-in solution, applicable to all active material chemistries in Li-Ion and Na-Ion batteries;
(2) it is transferable to other battery technologies (e.g, Al-Ion);
(3) it safeguards against a full range of abuse scenarios triggering thermal runaway; and
(4) the protection mechanisms will be reversible with lifetime benefits of batteries under real-world situations.

Smart additives will be developed utilising rational materials design driven by close integration between simulations at the atomistic and micro-scale with a comprehensive synthesis and characterisation program including a full array of in operando advanced electrochemical/spectroscopic techniques and x-ray tomography, complemented by state-of-the-art ex situ materials characterisation. Relevant abuse protocols will be developed and utilised to test batteries comprising electrodes with the smart additives at the cell and pack level. Further, we will exploit secondary characteristics of the smart additives to realise and demonstrate high-fidelity, non-invasive diagnostics and battery management to add an active safety layer for superior longevity.

Alignment with ISCF objectives:
Bringing together a complete value chain including SMIs (REAPsystems, Denchi), tier 1+2 suppliers (Johnson Matthey, Faradion, Yuasa), and larger OEMs (QinetiQ, Lloyd's, Dstl) with leading academics from engineering and chemistry (objectives 3+4), this project will innovate to deliver safer battery technologies and associated IP for automotive and other applications, increasing the UKs attractiveness for inward investment (objective 5) from global automotive OEMs and suppliers. Leveraged with over £150k support from industry, the program will increase the UKs R&D capacity/capability in battery research and deliver a world-leading, multi-disciplinary research program (objective 1) that is perfectly aligned with the 'Faraday Challenge' objectives, a UK flagship investment to develop and manufacture batteries for the electrification of vehicles (objective 2).

1) Impact will be achieved through physical and knowledge-based outputs:

Physical outputs of the programme:
- Smart battery electrode additives (ceramics and polymer composites) to arrest hot spots and thermal runaway
- Electrodes comprising these new smart additives with optimised morphology
- Safe and durable batteries and battery packs with high-fidelity battery management

Knowledge-based outputs of the programme:
- Examine operating batteries using x-ray tomography and associated multi-physics electrode models
- First Principles based phase diagrams and design maps of ceramic PTCR materials
- Optimised, high-fidelity battery management models
- Appropriate and validated thermal, electrical, and mechanical battery abuse testing protocols at cell and pack level

2) These outputs will have impact on:

Improvement in battery operational life and durability:
The new materials, modelling frameworks, and control strategies described above and produced within the project will lead to an improvement in battery operational life through divergence of current away from local hot-spots and non-invasive sensing of temperature rises and associated pre-emptive, high-fidelity BMS action. The associated reduction in whole-life costs will accelerate the uptake of these systems.

Improvement in battery safety:
The smart electrode additives developed in the programme provide a drop-in solution to make ANY active material chemistry resilient against thermal runaway, enabling exploitation of volatile chemistries with highest energy density and rate capability without compromising safety. Electrode conductivity additives could potentially be replaced weight/volume neutral or with a moderate increase of specific weight/volume at electrode level. The resulting redundancy of some external, standard safety measures, however, will reduce system size, complexity, and cost and, hence, increase energy density on the system level in terms of Wh/g and Wh/l. Likewise, the potential to classify Li-Ion and Na-Ion batteries as non-hazardous goods would reduce life-cycle costs (e.g., for certification, transport, and insurance) providing some leeway to exploit higher value materials.

3) Impact will be ensured by:

Academic dissemination routes:
- Research publications as described under "Academic beneficiaries"
- Regular contributions to the "UKES201x" conferences
- Publication of datasets and other digital output (including minting DOIs) and developed codes

Knowledge transfer between industry and academia:
The proposal enjoys strong industry support with in-kind support in excess of £150k. Our industrial collaborators, ranging from UK SMEs to multinationals, form a complete value chain. Knowledge transfer will be facilitated by
- Annual industrial steering group meetings
- Combination of one of the steering group meetings with a dedicated workshop
- Opportunities for targeted placements of staff with industry
- Development of a strong IP position with support from the Universities Research and Innovation Service

Engagement with regulatory bodies:
- Steering group representation of regulatory bodies
- Publication of abuse testing protocols and associated data

Engagement with the interested public (outreach):
- Contributions to the 'Bring Research to Life' Roadshow
- Curation of battery reliability and safety knowledge on Wikipedia